Hydrocarbon Processing January 2011

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JANUARY 2011

HPIMPACT SPECIALREPORT 2011FORECAST

GAS PROCESSINGGAS PROCESSINGDEVELOPMENTSDEVELOPMENTS

Improved technologiesImproved technologiestreat sour gastreat sour gas

Refinery constructionRefinery constructioncosts on the risecosts on the rise

Shale gas could affect Shale gas could affect Middle East LNGMiddle East LNG

HPI MARKETDATA 2011HPI MARKETDATA 2011

Summary reviews Summary reviews spending and trends spending and trends shaping the global HPIshaping the global HPI


XX Dewitt petrochemical-conference out look

XX Six strategic business technologies to watch

XX Australia making crucial GTL decisions

XX IEA assesses energy poli-cies of U.S.

XX Creating more value in capital projects

HPIMPACT

Cutline for fig.00

cutline for fig00

cutline for fig00


JANUARY 2011 • VOL. 90 NO. 1

SPECIAL REPORT: GAS PROCESSING DEVELOPMENTS

37 Consider different alternatives for enriching lean acid gases

New developments improve operation of Claus sulfur recovery units

B. ZareNezhad

41 Avoid condensation-induced transient pressure waves Case studies give an indication as to probable causes for water hammer

G. Mani

45 When is CO2 more hazardous than H2S Data shows potential harmful effects to workers due to acid gas exposure

K. Tyndall, K. McIntush, J. Lundeen, K. Fisher and C. Beitler

49 Use online analyzers for successful monitoring Improved analytics measure moisture and dew points for natural gas components A. Benton and C. Valiz

55 Advanced chemical process for treating sour gas Technology avoids huge capital investments while speeding up results

C. A. Ortega Peralta and M. J. Ortega Casteln

Cover The PERU LNG production complex in Pampa Melchorita, Peru, was officially inaugurated in June 2010. With a nominal capacity of 4.4 million tons of LNG per annum, it is South America’s first baseload liquefaction plant and represents one of the largest industrial projects ever undertaken in Peru. Photo courtesy of CB&I.

HPIMPACT17 Refinery and petro-

chemical construction costs continue measured rise

17 Moving beyond the meltdown in the Gulf

20 Global energy outlook to 2035

COLUMNS9 HPIN RELIABILITY

Packing not best practice for firewater pumps

11 HPIN EUROPEEuropean consumers mull their options as oil companies quit the market

13 HPINTEGRATION STRATEGIESMPC vs. ARC—Not an ‘either/or’ decision

90 HPIN CONTROLProcess control practice renewal—select CVs

PLANT SAFETY 57 Safe detection of small to large gas releases

Look at these advantages in using ultrasonic leak detectors E. Naranjo, S. Baliga, G. A. Neethling and C. D. Plummer

63 Considerations for blast-resistant electrical equipment centers Guidelines explore protecting critical systems from disaster

D. Cole and D. Austin

ENVIRONMENT 69 What are the strategies for sustainable chemical production?

New environmental challenges require a new way of thinking by the hydrocarbon processing industry

M. P. Sukumaran Nair

ROTATING EQUIPMENT 79 Going ‘green’ with FCC expander technology

New options recover waste gas energy as steam and electricity for plant use B. Carbonetto and P. Pecchi

ENGINEERING CASE HISTORIES 85 Case 60: Socket-weld failures

A risk analysis can determine which critical welds to repair T. Sofronas

DEPARTMENTS

7 HPIN BRIEF • 27 HPINNOVATIONS • 31 HPIN CONSTRUCTION

35 HPI CONSTRUCTION BOXSCORE UPDATE

86 HPI MARKETPLACE • 89 ADVERTISER INDEX

HPI 2011 FORECAST

21 HPI Market Data 2011 Executive Summary: This summary reviews spending for the global HPI. Will 2011 be a better year for the refining, petrochemical and natural gas industries? What lies ahead for the energy industry?

4

EDITORIAL Executive Editor Stephany RomanowProcess Editor Tricia CrosseyReliability/Equipment Editor Heinz P. BlochNews Editor Billy ThinnesAssociate Editor Helen Meche

European Editor Tim Lloyd WrightContributing Editor Loraine A. HuchlerContributing Editor William M. GobleContributing Editor Y. Zak FriedmanContributing Editor ARC Advisory Group (various)

MAGAZINE PRODUCTIONDirector—Editorial Production Sheryl StoneManager— Editorial Production Angela BatheArtist/Illustrator David WeeksManager—Advertising Production Cheryl Willis

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Because Hydrocarbon Processing is edited spe-cifically to be of greatest value to people work-ing in this specialized business, subscriptions are restricted to those engaged in the hydro-carbon processing industry, or service and sup-ply company personnel connected thereto.

Hydrocarbon Processing is indexed by Applied Science & Tech nology Index, by Chemical Abstracts and by Engineering Index Inc. Microfilm copies available through University Microfilms, International, Ann Arbor, Mich. The full text of Hydrocarbon Processing is also available in electronic versions of the Business Periodicals Index.

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HYDROCARBON PROCESSING (ISSN 0018-8190) is published monthly by Gulf Publishing Co., 2 Greenway Plaza, Suite 1020, Houston, Texas 77046. Periodicals postage paid at Houston, Texas, and at additional mailing office. POSTMASTER: Send address changes to Hydrocarbon Processing, P.O. Box 2608, Houston, Texas 77252.

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HYDROCARBON PROCESSING JANUARY 2011 I 7

The outlook for the US chemicals manufacturing sector is improving gradually and global production is set to increase in the coming year, thanks in part to dramatic growth in export markets for the products of chemis-try, according to a report from the American Chemistry Council (ACC).

For 2010, US chemistry exports will be up by 17%, shifting the trade balance for the industry from a $0.1 billion deficit to a $3.7 billion surplus, its best performance in 10 years. The growth in export markets also has partially offset soft domestic demand for chemical products.

Domestically, chemical production volumes have increased across all regions of the US in 2010 following steep declines in 2008 and 2009. The largest gains have occurred in the Gulf Coast and Ohio Valley regions, boosted by export demand for basic chemicals and plastics. Output is expected to grow moderately in all regions in 2011 and continue to improve through 2012.

Growth in export markets is driven by several factors, including favorable energy costs, resulting from develop-ments in extracting natural gas from shale; and growth in emerging mar-kets, where recovery, and now expan-sion, has been strongest.

US natural gas markets have seen a dynamic shift over the past five years as a result of increased capacity to extract natural gas from organic shale deposits. Reserves have risen by one-third, resulting in lower prices and greater availability of ethane, a feedstock material derived from natu-ral gas that is the basis for hundreds of manufactured products. This low price for natural gas compared to oil has enabled US chemicals manufac-turers to become more competitive than producers in much of the rest of the world.

Growth in emerging markets, most notably in China, India and Brazil, is increasing demand for chemistry feed-stock materials. Production of chemis-try products in emerging economies increased by 12.2% in 2010, and fur-ther gains are expected. HP

[email protected]

BILLY THINNES, NEWS EDITOR

HPIN BRIEF

Sunoco, Inc., will sell its 170,000-bpd refinery in Toledo, Ohio, to Toledo Refining Co., a subsidiary of PBF Holding Co., for approximately $400 million (consisting of $200 million in cash and a $200 million two-year note). In addition, the purchase agreement includes a participation payment of up to $125 million based on the future profitability of the refinery. The buyer will also purchase the crude oil and refined product inventory attributable to the refinery, which will be valued at market prices at closing. The transaction is expected to be completed early in the first quarter of 2011.

The Alliance for Climate Protection and the Center for American Progress released a joint report that calls on the US to take the lead on international climate finance—even under the current difficult political and economic condi-tions. The report says that it is in the US’ best interest to help developing nations reduce greenhouse-gas emissions and build clean-energy economies. It calls on the US to lead a global partnership to mobilize new investments in developing countries between now and 2015, and urges the country to explore new ways to help develop-ing countries pursue clean-energy growth. The report suggests the US can finance investments through public budget resources, carbon markets, development bank lending and private financing.

ABB will acquire Baldor Electric in an all-cash transaction valued at approximately $4.2 billion, including $1.1 billion of net debt. The transaction closes a gap in ABB’s automation portfolio in North America by adding Baldor’s NEMA motors product line. Baldor also adds a mechanical power transmission business to ABB’s portfolio. The US market for high-efficiency motors is expected to grow 10% to 15% in 2011 on the back of new regulations, effective in December this year. Similar regulations in Canada, Mexico and in the European Union are expected in 2011.

The chairman of the US Chemical Safety Board (CSB) applauded the National Fire Protection Association (NFPA) for its recent decision to establish a new technical committee to develop a comprehensive standard for gas processing safety, including the cleaning of fuel gas piping systems. The NFPA acted in response to an urgent recommendation issued by the CSB following a catastrophic natural gas explo-sion at Kleen Energy, a power plant under construction in Middletown, Connecticut, on February 7, 2010. In that incident, workers were conducting a “gas blow,” a procedure that forced natural gas at high volume and pressure through newly installed piping to remove debris. The gas was vented to the atmosphere, where it accumulated and explod-ed, killing six contract workers and injuring many others.

Early December marked a major milestone for the US’ transition to ultra-low-sulfur diesel (ULSD) fuel, as all highway diesel fuel in the US now complies with the 15-ppm sulfur standard. This represents a 97% reduction in sulfur content from diesel’s 2006 levels. The December 1, 2010, deadline was mandated by the US Environmental Protection Agency (EPA). However, according to the EPA’s pump survey, the highway transition to ULSD was actually completed a few weeks ahead of schedule.

BASF and PETRONAS are studying the possibility of producing specialty chemicals in Malaysia, a move that would extend the two parties’ existing business collaboration in the country. The partners are considering a potential joint investment sum of approximately €1 billion, along with operating facilities for the production of specialty chemicals including non-ionic surfactants, methanesulfonic acid, iso-nonanol as well as other C4-based specialty chemical products. A decision is expected in 2011. HP

■ Improved outlook for US chemicals

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HEINZ P. BLOCH, RELIABILITY/EQUIPMENT EDITOR

HPIN RELIABILITY

[email protected]


Statistics show that for every 1,000 pump failures in hydrocar-bon processing plants, there will be a fire. Fig. 1 shows a typical visible outcome, and the final bill for remedying such disastrous results can amount to hundreds of millions of dollars.

Since roughly 60% of pump fires involve mechanical seal failures, it has been assumed that the majority of mechanical seals are somehow flawed. However, this conclusion is quite incorrect. Many pumps have been in service for years without seal fail-ures. The entire experience points to the need to carefully select the right mechanical seal designs and to follow up by adhering to appropriate work processes and installation procedures.

Braided packing or mechanical seals? There is still the occasional assumption that critically important pumps will benefit from braided packing. Firewater pumps are mentioned in this context since they are expected to be available at all times and because, with water, a small amount of leakage is deemed tolerable. It might surprise some readers that, even here, packing is not the first choice of experienced professionals. Best practice in modern firewater pumps has been (since about 1968) to use single-spring mechanical seals. As was mentioned in the July 2010 HPIn Reliability column, these mechanical seals are to be backed up by a floating throttle bushing and a deflector guard.

Reliability professionals interested in “designing out” mainte-nance always check into the feasibility of systematically upgrading their equipment. In fact, the very best HP companies mandate viewing every maintenance event as an opportunity to upgrade. For process pumps, one of the many cost-effective upgrade mea-sures involves replacing the plain deflector guards that had been introduced in the 1950s. It is of more than historical interest to review what led to the recommendation and to use single-spring mechanical seals instead of packing.

In the 1960s, accurate statistics were kept (for insurance pur-poses) by a major multinational oil company. The statistics for firewater pumps showed that leaking packing tended to ruin bear-ings. Well-designed mechanical seals were then selected because they generally leak much less than packing and are considerably less likely to allow water spray to enter the adjacent bearing hous-ing. Of course, we know that brittle mechanical seal faces might shatter when abused. However, seals that are properly designed, selected and installed are highly unlikely to shatter. Moreover, floating throttle bushings represent a “second line of defense” in firewater pumps.

Testing your firewater pumps. Proper operating and maintenance best practices require periodic testing of all standby equipment. Periodic testing is mandatory, and testing once every two weeks is not unreasonable. Each firewater pump would then be allowed to run for about an hour. Different rules may pertain to process pumps in other services.

For process pumps, the question is often asked differently. Some facilities believe that switching the “A” and “B” pumps and running each for a given time (months) is best. Another group believes that simply turning on the standby pump once a month and then running it for 4–6 hours is a better alternative. Which of the two is preferred?

When people argued—many decades ago—that plants might get away with testing pumps as infrequently as twice a year, responsible reliability professionals took the position that testing only twice a year would not be acceptable and monthly testing was needed. Depending on lubricant selection and lube application method, switching “A” and “B” every two months is considered best practice. This then keeps the bearings lubricated, prevents the rolling elements from sitting in exactly the same position and prevents seal faces from sticking.

Back to the issue of firewater pump sealing practices. Knowl-edgeable engineers do not advocate using packing in modern firewater pumps. The reasons are technical and were described above, but the reasons are also workforce and experience-related. Consider the difficulty of grooming and retaining top-notch maintenance personnel in some plants. Taken together, decades of experience and an examination of present-day workforce avail-abilities support the contention that packing no longer represents best practice at the most advanced companies. HP

Packing not best practice for firewater pumps

The author is Hydrocarbon Processing’s Reliability/Equipment Editor. The author of 18 textbooks and over 490 papers or articles, he advises process plants worldwide on reliability improvement and maintenance cost reduction opportuni-ties. For more details, see his “Practical Lubrication for Industrial Facilities,” ISBN 0-88173-579-5.

Scene of a refinery pump fire (Source: Release No. 2004-08-I-NM; US Chemical Safety Board; http://www.csb.gov).

FIG. 1

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TIM LLOYD WRIGHT, EUROPEAN EDITOR

HPIN EUROPE

[email protected]


Although I’ve watched it coming, it still feels like a historic moment to see the oil industry pack up its things and leave. If you sell catalysts, pumps, inspection services, display ads or anti-static additives, then that low rumble is the ground moving—your market is changing under your feet.

New supplier on the horizon. People who buy fuel are waking up to a different logo on the tank truck and another voice on the telephone. Some are realizing too late that they’ll be los-ing a supplier with a certain standing, a reputation to preen and a level of expertise that they’ve come to count on. And if you’re not supplying, but manning a refinery or a marketing operation in Europe, then it isn’t just you. It’s happening all over. You’re not the only one seeing a new set of suits wandering through your workplace measuring you up.

“We’ve had a room in the center of the main floor set up as a data room all summer,” one oil major executive told me on a recent visit. “People have had their teams coming in and running our numbers for months. The whole business is up for sale.”

The international oil companies are bidding their farewells, and a new breed of nontraditional suppliers is doing its due dili-gence. For example, in the UK, half of the retail stations could change hands in the next few years, the Financial Times reckoned recently. France’s Total is selling its 780 stations in the country; Murphy Oil is selling its 480 stations. The Chevron Texaco busi-ness in the UK and Ireland is up for sale. It operates 1,300 stations under the Texaco brand. Exxon Mobil wants to supply, but no longer own and operate its Scottish forecourts. The sale or closure of numerous European refineries by Shell, Total, Chevron Texaco, ConocoPhillips and Petroplus is no longer a consultant’s projec-tion, but an emerging reality.

‘New’ oil company. At a recent meeting of fuel buyers in the global aviation industry, one of the companies investing now to assume major oil market share was exuding confidence.

Ian Taylor is CEO of Vitol, one of the world’s largest trading groups, a company that has come to be known to the airlines as one of the new “nontraditional” suppliers. He effectively thanked BP and Shell for their service and told the audience his company would take over from here. He went on to restate Vitol’s ongoing plans to take over Shell Aviation businesses all over Africa. Days later, Trafigura, another very substantial trading group, announced it would take over from BP in a number of southern African states. Chevron Corp. has sold its Caribbean and Central American fuels and aviation busi-nesses recently to Rubis, a French midstream group.

And it’s not just around the equator and in the southern hemi-sphere that the nontraditional suppliers are moving in. Morgan Stanley, the bank, is aggressively pursuing aviation custom in European markets, having traded fuels for many years. One of

its executives shared a stage at the aviation conference with the managing director of the newly launched Vitol Aviation.

In the UK, Greenergy, the company I’ve followed since it was a half-dozen desks gathered around an oversized “Scalextric” toy car track, is bidding to buy up hundreds of service stations. It has already built one of the UK’s largest private businesses out of taking over clean fuels niches and later marketing functions, from major companies. Today, it delivers some 140 million liters (37 million US gallons) of fuel a week, but, like Vitol and Trafigura, it all started with oil trading.

The oil companies aren’t getting out of supply roles across the board. Shell is at pains to point out that it intends to grow in some aviation markets as it leaves others. But the trend is unmistakable. “Look at an average major,” a bank researcher friend told me. “They may have 100,000 people, of which 70,000 work down-stream. Yet 80% of their profits are coming from the upstream. They’re running the numbers and concluding, ‘why bother?’

John Digby, an independent consultant and former boss at Chevron Texaco, says that in the first half of 2010, upstream income accounted for some $48.6 billion at six leading major oil companies, while downstream income accounted for just $9.6 billion—a ratio of five to one. But it’s more than nostalgia that has some oil market end users flustered at the changes.

The chair of an International Air Transport Association techni-cal meeting wanted to know recently where were the expert rep-resentatives from the new suppliers in his working groups as they try to understand the salt contamination issue that recently led to a near disaster aboard a Cathay Pacific flight leaving Indonesia.

“We’ll buy in expertise from the majors,” one of the trading groups told me. “We can’t afford to have any quality issues at all,” he added. That’s no doubt true, but one has to wonder what will be left of the quality assurance and long-term research and development function in the fuels supply industry. Admittedly, the oil companies themselves shrank technical and research facilities like Thornton and Sunbury very significantly during the 1990s, but will their research and technical facilities in the region now fade to nothing?

And there’s another thing. As the international oil companies head off to spend the remaining decades of the oil age in more rewarding upstream pastures, the oil products markets are being handed to trad-ers and banks. Granted, there’ll be new competition among the new suppliers with a nose for sourcing cost-effective streams of product. But end users may well be wary of what they see as a change from dealing with expert producers, to expert “middle-men.” HP

The author is HP’s European Editor and also a specialist in European distillate markets. He has been active as a reporter and conference chair in the European downstream industry since 1997, before which he was a feature writer and reporter for the UK broadsheet press and BBC radio. Mr. Wright lives in Sweden and is the founder of a local climate and sustainability initiative.

European consumers mull their options as oil companies quit the market

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DICK HILL, CONTRIBUTING EDITOR

HPINTEGRATION STRATEGIES

[email protected]


Overview. In the 35 years since they introduced distributed control systems (DCSs), automation system suppliers have pro-vided the hydrocarbon processing industry (HPI) and other customers with far more than the ubiquitous piping and instru-mentation diagram (PID) control-function block in their suite of available function blocks. Many of the additional DCS function blocks originated back in the days before multivariable or model-predictive control (MPC) was commercially available. We now refer to putting together functions such as lead-lag, dead time or selectors to formulate advanced control as advanced regula-tory control (ARC). ARC and MPC are both types of advanced process control (APC).

While DCSs provide advanced control capabilities in the many useful function blocks available, some end users in the HPI and other heavy process plants moved away from function blocks in favor of developing MPC models for APC.

Getting the foundation right. Before MPC, if the pro-cess required advanced-control techniques, the process control practitioners had to assemble the correct control functions to achieve the required results. These evolved into what we now call ARC. Modern process control assumes that the regulatory control provided by the process control system is solid, with well-tuned loops and controllers operating in the correct mode. Without good basic regulatory control, APC will not perform well. But what about ARC? Now that MPC is so widely accepted and used, are control engineers and other practitioners still taking advantage of the ARC capabilities built into most DCSs?

MPC isn’t the only tool in the toolbox. An entire culture has evolved around the use of MPC. MPC has earned widespread respect and acceptance due to its often-spectacular payback. Despite the considerable implementation cost often involved, users have cited MPC projects that have delivered return on investment in 18 months or less. As a result, the “culture of MPC” might unduly influence some companies to implement MPC, when, in some cases, ARC implemented right in the DCS control blocks might actually provide the best solution.

Not highlighted as much is the fact that MPC requires a continued investment. The models are built based on the set of process conditions, feedstocks, ambient conditions, variable interactions and business objectives that exist at that point in time. However, any or all of these may change, requiring the model to be modified or rebuilt for the MPC to continue driv-ing value.

Balancing ARC and MPC. So here’s a good question: If all the process needs to perform better is feedforward, do you really need to build (and maintain) a model to accomplish this? In many instances, advanced control could be accomplished

by configuring function blocks and tuning each to remove loop interaction and to provide feedforward action and other advanced regulatory control techniques. If so, could this pos-sibly be a better approach than MPC? More to the point, how’s a plant to decide?

There is no substitute for knowing your process and the skills of your control personnel. The process control culture in any plant or company has evolved over many years with deep roots in “how we’ve always done it.” All plants must continuously maintain basic regulatory control to provide the stable, well-tuned base layer. However, above this foundation, plants have options for performing APC functions.

It’s important to note here that the choice of which technol-ogy to use for APC—whether MPC or ARC—is not an “either/or” decision, but rather a matter of understanding which tool, or combination of tools, is best for each application. But how do you know if you have the right balance?

The decision to implement an advanced-control application using MPC, ARC or some combination is more than a technol-ogy decision. Both tool sets can perform well for a variety of applications. Users must take support for the implemented appli-cation into consideration. If the staff at the site is not trained in maintaining MPC models, then ARC could be a better choice. If uniformity across the enterprise is important, it is important that the company considers how it will support remote locations, regardless of whether it chooses MPC or ARC.

In the end, both MPC and ARC may be the right decision. Some applications will lend themselves to using DCS function blocks, while others are best solved using model predictive controllers.

If you question whether you’re using the right combination, benchmarking can help you at least determine if you are alone or with the majority. End users in process plants may find it worth-while to participate in ARC Advisory Group’s Benchmarking Consortium, which addresses MPC performance and other key issues. For more information, HP readers can visit http://www.arcweb.com/Benchmarking. HP

MPC vs. ARC—Not an ‘either/or’ decision

The author is vice president of ARC Advisory Group, Dedham, Massachusetts, responsible for developing the strategic direction for ARC products, services and geographical expansion. He is responsible for covering advanced software business worldwide. In addition, he provides leadership for support of ARC's automation team and clients. Mr. Hill has over 30 years of experience in manufacturing and automation. He has broad international experience with The Foxboro Company. Prior to Foxboro, Mr. Hill was a senior process control engineer with BP Oil, develop-ing and implementing advanced process control applications. Prior to joining ARC, he was the US general manager of Walsh Automation, a major engineering con-sulting firm and supplier of CIM solutions to the pulp and paper, petrochemicals, pharmaceutical, and other process and manufacturing industries. He is a graduate from Lowell Technological Institute with a BS degree in chemical engineering.

SÜ[email protected]

Industry executives, technical experts and analysts will be discussing the latest innovations and breakthroughs in catalysis, process engineering, battery materials and water treatment technologies applied in these fi elds at the “Defi ning the Future V Conference.” Through open exchange and in-depth discussion, it is our goal to offer valuable insight into opportunities and challenges the industries are facing, and to support the formulation of strategies that can be developed to address them. This conference will be comprised of parallel sessions on:

• Refi ning Industries• Chemical Industries• Petrochemical Industries & Polyolefi n Plants• Coal-To-Chemicals (Methanol & Derivatives)• Environmental Technologies• Battery Materials

• Water Treatment Technologies

Please mark your calendar and join us in Beijing!

Süd-Chemie Defi ning the Future V ConferenceMay 23-25, 2011 – Beijing, China

SC_DTF_V_Anz_210x280_f01.indd 1 27.10.2010 16:00:32 Uhr



HPIMPACT

Refinery and petrochemical construction costs continue measured rise

The costs for designing and constructing downstream refining and petrochemical projects rose 3% from Q1 2010 to Q3 2010, according to the latest edition of the IHS CERA Downstream Capital Costs Index (DCCI). It was the third straight increase for the index since prices bottomed out at 9% below peak 2008 levels. Costs are now just 4% below their 2008 peak.

The IHS CERA DCCI is a proprietary measure of project cost inflation similar in concept to the Consumer Price Index (CPI). It provides a benchmark for comparing costs around the world and draws upon proprietary IHS and IHS CERA databases and analytical tools. The current DCCI rose from 175 to 180 over the past six months. The values are indexed to the year 2000, mean-ing that a project that cost $100 in 2000 would cost $180 today.

Higher commodity prices and a weakening US dollar contin-ued to be the driving force behind the steady rise of costs in the downstream sector.

“The momentum in the rise of costs back to prerecession lev-els is really a ‘slowmentum’ [sic] reflective of the broader global economic recovery,” said IHS CERA Chairman Daniel Yergin. “Activity is increasing and prices are rising, albeit with a healthy dose of caution.”

Commodities prices were driven by the global economy’s recovery and increased construction activity as the impact of the fiscal stimuli was felt by the wider economy. Steel prices continued to show high degrees of volatility as iron ore producers switched from adjusting prices annually to adjusting them every quarter, reflecting market-based demand-supply fundamentals.

The continued weakening of the US dollar also contributed to the rise of commodity prices while also driving up costs of equip-ment, labor and engineering and project management costs. The dollar’s fall was driven by the US Federal Reserve’s second round of quantitative easing to reinvigorate the US economy—the Fed recently announced a $600 billion plan to purchase treasury bonds over the next eight months.

Robust downstream construction activity in China, India and the Middle East continues unabated, according to the index. Record refining and ethylene capacity additions came online in 2009 and more projects are in various stages of engineering and construction. This trend is expected to continue until 2015. Government policies encourage investment in the downstream sector in anticipation of increasing demand for transportation fuels, plastics and fibers.

China plans to increase refining capacity by 50% in the next five years. Similarly, the Middle East is emerging as a major hub for petrochemicals with advantageous feedstock and government policies that incentivize diversification into other industries sup-ported by petrochemicals. Large complex refineries with integrated petrochemicals are emerging as the “new standard” to position the downstream sector for profitability.

The capacity additions in Asia will continue to put downward pressure on margins as excess capacity emerges in the face of

tepid consumer demand. Refiners and petrochemical companies in Organization for Economic Cooperation and Development (OECD) countries—which have been rationalizing refining capacity—will continue to face rising pressure to shut down older and less efficient plants with poor economics.

“The economic outlook ahead appears to be mixed with rising prospects that the recent momentum will give way to an impend-ing slowdown,” said Farooq Sheikh, lead researcher for the IHS CERA Capital Costs Analysis Forum for Downstream. “China also appears to be slowing down as the government increasingly restrains the fiscal stimulus and has recently increased interest rates by a quarter percent in fear of a real-estate bubble.”

Developing countries are showing increasing concerns about capital flows into their markets creating an asset bubble. Capital controls and higher interest rates are being employed to temper unbridled growth.

As a result, the IHS CERA DCCI concludes that another mod-est increase is expected in downstream capital costs in the near term as recovering construction activity and further increases in raw materials prices push costs closer to their pre-recession highs.

Moving beyond the meltdown in the GulfAccording to Deloitte Center for Energy Solutions’ recent study,

the Gulf of Mexico deepwater drilling remains vital to the US economy and is vital for future growth. For the record, “easy oil” is gone; oil companies must venture to more challenging regions to explore and produce (E&P) crude oil. Such projects will require bil-lions of dollars of investment in new technologies to produce crude oil and natural gas at depths greater than 5,000 feet under water. For the Western Hemisphere, the Gulf remains a “hot bed” of E&P activity. This region’s crude oil reserves can provide a significant and secure source of domestic energy to the US. At present, 30% of the US’ oil supplies come from the Gulf of Mexico, and this region provides an economic engine to the US by creating over thousands of jobs and more than $11 billion a year in royalties and taxes.

One event. For years, E&P companies have safety operated in the Gulf without incident; but everything change with the Deep-water Horizon tragedy. In response to this drilling rig accident, the US Department of Interior (DOI) immediately set in place a six-month moratorium on new shallow and deepwater drilling. The moratorium is affecting E&P operations in the Gulf. Delays in new oil supplies have contributed to the increase in oil prices during the Q4 of 2010 and the tightening in US crude supplies. The American Petroleum Institute estimates that a production loss of 80,000 bpd to 130,000 bpd of crude oil could be felt in the US market by 2015. The International Energy Agency estimates that between 100,000 bbls to 800,000 bbls of new oil supply could be deferred under the new rules, making it more difficult to sup-ply US demand. More imports will be required to cover the gap between supply and demand.

New realities. In addition to the stay on new drilling, the DOI is imposing more rules to promote safe and reliable operations on drilling operations. The regulations set guidelines over new opera-tions and procedures, certifications, backup control systems, new

BILLY THINNES, NEWS EDITOR

[email protected]

T H E W O R L D T U R N S T O E L L I O T T

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HPIMPACT

17

rig (equipment) and materials, and demonstrations of available backup blowout containment resources. Permitting delays are anticipated due to the extended regulatory reviews now in place.

Price of risk. Following the Deepwater Horizon event, E&P companies must evaluate their potential risk exposure at $30 bil-lion when operating in the Gulf, up considerably from $75 mil-lion. In a recent Deloitte survey of approximately 300 companies operating in the Gulf, only 10 international and national oil com-panies have capitalization and a balance sheet that could withstand this level of liability. In addition, 40% of the companies working in the Gulf have a market capitalization of $5 billion or less—well below the new level of risk exposure. Toler-ance to risk is changing the environment within the Gulf. Some companies will con-tinue to pursue projects; other companies will go to less risk areas. A mass exodus of oil and gas companies from the Gulf will have a negative impact on the US economy.

The Deepwater Horizon accident was a tragedy that will be felt for many years. More important, many lessons have been learned through this experience by government and industry that will be most beneficial for future operations. Government and industry must find a common ground to move for-ward and to keep the Gulf open for business.

Update. In a reversal, the Obama administration said on Dec. 1 that it will not pursue offshore drilling off the East Coast of the US and the eastern Gulf of Mexico. Because of the BP oil spill, the Interior Department will not propose any new oil drilling in waters off the East Coast for at least the next seven years.

President Barack Obama’s earlier plan—announced in March, three weeks before the April BP spill—would have authorized officials to explore the potential for drilling from Delaware to central Florida, plus the northern waters of Alaska. The new plan allows potential drilling in Alaska, but offi-cials said they will move cautiously before approving any leases.

A spokeswoman for the US Chamber of Commerce said the decision represents a major step backward for the nation’s energy future. “The decision comes on top of the de facto moratorium the administration has imposed on production in both deep and shallow waters in the Gulf and Alaska, which is already causing significant harm to our economy and our energy security,” said Karen Harbert, president and CEO of the Chamber’s Institute for 21st Century Energy.

Global energy outlook to 2035

According to the International Energy Agency’s (IEA’s) World Energy Outlook 2010, the energy world market faces

unprecedented uncertainty. The 2008–2009 global economic crisis threw the energy markets into severe turmoil. The pace of the global economic recovery holds the key to energy prospects for the next several years, but it will be governments’ responses to the twin challenges of climate change and energy security that will shape the future of energy in the longer term. The worst of the global economic crisis appears to be over. But it will be a hard fight to return to pre-2008 energy levels. In looking ahead, IEA forecasts some changes in the global energy market:

• Global primary energy demand will increase by 36% between 2008 and 2035, or 1.2%/yr on average. This com-


18 I JANUARY 2011 HYDROCARBON PROCESSING

HPIMPACT

pares with 2%/yr predicted from the previous 27-year study. Slower growth is due to national pledges to reduce greenhouse-gas (GHG) emissions and plans to phase out fossil-fuel subsidies.

• Non-OECD countries account for 93% of the projected increase in global energy demand. China, where demand has surged over the past decade, will contribute 36% to the projected growth in global energy use; its demand is rising by 75% between 2008 and 2035 (Fig. 1). China overtook the US in 2009 to become the world’s largest energy user. Aggregate energy demand in OECD countries is forecast to rise very slowly.

• Global demand for fossil fuels will account for over 50% of the increase in total primary energy demand. Rising fossil-fuel prices for end users, resulting from upward price pressures in international markets and, increasingly, carbon penalties in many countries, will encourage energy savings and switching to low-car-bon energy sources, to restrain demand growth for all three fuels.

• Oil remains the dominant fuel in the energy mix. Oil’s share of the primary fuel mix diminishes as higher oil prices and government measures to promote fuel efficiency support fuel switching. Demand for coal rises through 2020 and starts to decline. The share of nuclear power increases from 6% in 2008 to 8% in 2035. Use of modern renewable energy—including hydro,

wind, solar, geothermal, modern biomass and marine energy—triples between 2008 and 2035. Its share in total energy demand increase from 7% to 14%.

• Natural gas will play a central role in meeting the world’s energy needs. Global natural gas demand, which fell in 2009, is set to resume its long-term upward trajectory from 2010. Demand will increase by 44% between 2008 and 2035—at an average of 1.4%/yr. Demand growth for gas far surpasses that for the other fossil fuels due to its more favorable environmental and practical attributes, and constraints on how quickly low-carbon energy technologies can be deployed. China’s gas demand will grow the fastest, accounting for more than one-fifth of the increase in global demand to 2035. The Middle East leads in expansion of natural gas production; its output is estimated to double by 2035.

What will shape the future of oil? The global outlook for oil remains highly sensitive to policy action to curb rising demand and emissions. Primary oil use will increases in absolute terms between 2009 and 2035, driven by population and economic growth, but demand is forecast to decline in response to radical policy action to curb fossil-fuel use. Other trends are:

• The oil price needed to balance oil markets is set to rise, reflecting the growing insensitivity of both demand and supply to price. The growing concentration of oil use in transport and a shift of demand toward markets where subsidies are most prevalent are limiting the scope for higher prices to choke off demand and discouraging fuel switching. Constraints on investment mean that higher prices lead to only modest increases in production. In the New Policies Scenario, the average IEA crude oil price reaches $113/bbl (2009 dollars) in 2035—up from just over $60/bbl in 2009.

• Oil demand (excluding biofuels) continues to grow steadily reaching about 99 million bpd (MMbpd) by 2035. Non-OECD nations are responsible for the net growth—almost half from China alone. Demand by OECD nations falls by over 6 MMbpd. Global oil production reaches 96 MMbpd, the balance of 3 MMbpd coming from processing gains. Crude oil output reaches an undulating plateau of around 68–69 MMbpd by 2020, but never regains its all-time peak of 70 MMbpd reached in 2006, while production of natural gas liquids (NGLs) and unconven-tional oil grows strongly (Fig. 2). Total OPEC production rises continually through to 2035; its share of global output increasing from 41% to 52%.

• The eventual peak in oil demand will be determined by several factors affecting both demand and supply. Production in total does not peak before 2035, although it comes close to doing so. Oil prices are much lower as a result. If governments act more vigorously than currently planned to encourage more efficient use of oil and development of alternatives, then demand for oil may ease. Result: We might see a fairly early peak in oil production, which would help prolong the world’s oil reserves.

• Unconventional oil is set to play an increasingly impor-tant role in the world oil supply through to 2035, regardless of what governments’ actions to curb demand. Unconventional oil will meet about 10% of world oil demand compared with less than 3% today. Canadian oil sands and Venezuelan extra-heavy oil dominate the mix, but coal-to-liquids, gas-to-liquids and, to a lesser extent, oil shale also makes a growing contribution in the second half of the outlook period. HP

Expanded versions of these items can be found online at HydrocarbonProcessing.com.

Gas

Oil

Coal

OECDChinaRest of world

-600 -300 0 300 600 900 1,200 1,500

Otherrenewables

Hydro

Nuclear

Million toe

Energy demand by region, 2008–2035.FIG. 1

Crude oil fields yetto be developed or found

Unconventional oilNatural gas liquids

Crude oil—currentlyproducing fieldsTotal crude oil

60

80

100

mb

/d

0

20

40

60

1990 1995 2000 2005 2010 2015 2020 2025 2030 2035

World oil production by type, 1990–2035. FIG. 2

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Tim Lloyd Wright is HP’s European Editor and has been active as a reporter and conference chair in the European downstream industry since 1997, before which he was a feature writer and reporter for the UK broadsheet press and BBC radio. Mr. Wright lives in Sweden and is founder of a local climate and sustainability initiative.


www.GulfPub.com/2011HPI

HP EDITORIAL

HPI 2011 FORECAST

HPI Market Data 2011 Executive SummaryBACK FROM THE EDGE OF DESPAIR

Hydrocarbon Processing’s HPI Market Data 2011 report offers a detailed forecast for the direction that the hydrocarbon process-ing industry (HPI) is heading in 2011. The executive summary is reproduced here for your reading pleasure. Should you wish to purchase the whole report, please visit www.gulfpub.com.

Depending on the markets, HPI segment and processing facil-ity location, refiners and petrochemical producers can expect their business prospects to improve, tread water or take a turn for the worse. The report emphasizes that a new environment has arrived this year, and it will take courage and stamina by HPI companies to successfully navigate this constantly evolving economic and regulatory terrain.

The 2011 economic outlook for HPI companies is:

Improving. Half-way through 2010, it is the developing or non-Organization of Economic Co-operation and Development (non-OECD) nations that are pulling the rest of the world out of this downturn. As shown in Fig. 1, non-OECD nations are steadily increasing their consumption of crude oil. In contrast, OECD nations’ demand for crude oil peaked in 2006 at 49.5 million bpd (MM bpd) and has declined to an estimated 45.5 MM bpd in 2010. Yet, the total demand for crude oil has fluxed around 86 MM bpd over this same period, with a five-year average of 85.74 MM bpd.

In particular, it is China’s strong gross domestic product (GDP) and manufacturing powers that have remained positive during this downturn. As shown in Fig. 2, China is the major non-OECD

energy-consuming nation. In 2011, China will be responsible for about one-third of new crude-oil demand growth. In 2010, Chinese oil demand is forecast to rise 9.2%. Much of this rising demand is linking to a growing middle class in China.

Several economists predicted that significant changes would evolve due in part to the sharp decline in the global economy; such changes would move centers of influence as well. In mid-2010, China emerged as the No. 1 energy-consuming nation, sur-passing the US and Japan. This shift in leading energy-consuming nations was predicted to happen in 2015. However, the steep decline in energy consumption by the US and the steady, increas-ing expansion of the Chinese economy shifted China to the No. 1 energy-consuming nation five years sooner than forecast. With a strong economy, China has surpassed Japan as the second largest economy. Japan’s economy struggled before the 2008 downturn and, since then, has contracted even more, as shown in Fig. 2.

Treading water. The US economy still struggles to find for-ward momentum. The combination of high unemployment and a jobless recovery continues to stifle economic activity. Lower crude oil prices and natural gas prices eased processing and feed-stock costs. But consumers remain chilled on spending what incomes they still have. Housing starts remain mired, which hinders the petrochemical industry.

Taking a turn for the worse. Western Europe is experienc-ing new economic woes in 2010. High unemployment still chal-lenges the European Union (EU). In 2010, several EU nations

Total oil demand for OECD and non-OECD nations, 2006–2010.FIG. 1

49.5 49.2 47.6 45.5 45.5

35.6 37.2 38.4 39.3 40.9

85.1 86.4 86 84.8 86.4

010

20

30

40

50

60

70

80

90

100

2006 2007 2008

5-yr. avg. 85.74

2009 2010

Global oil demand, 2006–2010

Glo

bal

oil

dem

and

, m

illio

n b

pd

OECD Non-OECD Total

Source: Hydrocarbon Processing

HPI 2011 FORECAST


encountered more financial difficulties over deficit spending that unfortunately spilled over to neighboring nations. Just as in the US, EU consumer spending nearly evaporated in 2009, and the EU demand for petrochemicals declined 13.9%. The EU petro-chemical industry report a 9% increase over 2009 levels in 2010. But recovery to pre-2008 levels will take much longer, perhaps five years. In addition, a stronger US dollar against the euro created even more stress for this region. Several EU nations are tightening their financial belts to weather through this economic storm, thus adding more pressure to this region.

Beyond 2011. The global HPI is bruised from recent events. However, the HPI is intertwined in the daily lives of the aver-age consumer. Activity and consumption of HPI products will increase in non-OECD nations due in part to a growing middle class in China and India and increasing populations in developing nations. The “stampede to the East” will continue as more HPI complexes will be located in growing consumer markets as well as in locations with lower cost feedstocks and operating costs.

TOTAL SPENDINGHPI companies manage their spending habits via three bud-

gets—capital, maintenance and operating. In 2011, we believe that global improvements from 2010 will continue into the next year. While new project activity is stalled from the all-time high in 2007, the total active project count remains at record levels. The global GDP stagnated in 2010; some regions fared better than others. The developed nations (OECD nations) still struggle to get back on track, economically speaking. Demand for transporta-tion fuels and petrochemical consumer products is rising slowly, but not at rates desired by most governments. The meltdown of the banking and credit systems tightened access to capital and is still impacting the entire HPI community. More scrutiny is

applied by financial institutions to minimize their risk on major capital projects.

Greenshoots of economic stability began appearing in late 2009 and early 2010. However, recovery to pre-2008 levels will take more time, perhaps until 2015 by some forecasters. Yet, there is some good news; notably, energy costs have declined. This is a benefit for manufacturers and consumers. Dramatic reductions in natural gas and crude oil prices are easing operating spending. However, the near collapse in product demand and trade has created a surplus situation for various HPI products. It is taking longer for industry to work down excess inventories.

Looking forward, 2011 will continue to improve for the HPI. New project announcements declined in 2010 but did not evapo-rate. However, we should expect a more disciplined spending approach by major companies to trim costs across the entire value chain of their products and manufacturing centers. The bonus from the downturn has been a decline in construction, material and equipment costs.

HPI construction activity remains resilient, and new project additions still occurred even at the bottom point of the recession in early 2009. Investment in existing facilities will focus on improv-ing reliability and maintaining more onstream time while finding more production capacity through “creep” expansion projects. Growing demand for HPI products will be met by new grassroots installations in developing nations, particularly China and India.

In 2011, the HPI’s capital, maintenance, and operating budgets are expected to total $219.8 billion (Table 1). Capital spending is projected at $56.4 billion; maintenance spending should reach $63.9 billion, a $1.1 billion increase over 2010 spending; and operating spending is projected to be $99.5 billion. HPI companies are more cost conscious during tight credit times.

Capital spending exceeds $56 billion. HPI capital spend-ing is forecast to be more than $56 billion worldwide in 2011. As shown in Table 2, the 2011 capital spending total includes $25.1 billion in the refining sector, $16.6 billion in the petrochemical segment, approximately $10.5 billion in the gas processing sector and $4.3 billion in the synfuels sector. More than $28 billion of the capital budget will be spent on equipment and materials.

HPI companies are strengthening their balance sheets and are seeking opportunities to maximize their market shares through strategic capital investment. Caution is still applied in major projects and capital spending.

Companies in maturing HPI consuming regions, such as the US and EU, are implementing capacity additions through process modifications and retrofits. The need to maintain the reliability of existing assets and to increase energy efficiency are major goals in many revamp projects. Other energy-conservation and envi-ronmental improvements from innovative equipment and new processing technologies are also part of this investment strategy. The availability of new and improved equipment and construction

TABLE 1. 2011 Worldwide HPI total spending by budget, millionsType US Outside US Worldwide

Capital 9,660 46,770 56,430

Maintenance 15,333 48,542 63,875

Operating 30,386 69,090 99,476

Total 55,379 164,402 219,781

TABLE 2. 2011 Worldwide HPI capital spending by sector, millionsSector US Outside US Worldwide

Petrochemical/chemical 2,300 14,300 16,600

Refi ning 4,400 20,700 25,100

Gas processing 2,960 7,460 10,420

Synfuels – 4,310 4,310

Total 9,660 46,770 56,430

Oil demand changes in Asia-Pacific for OECD and non-OECD nations, 2007–2010,

FIG. 2

-600

-400

-200

0

200

400

600

800

2007 2008 2009 2010

OECD Pacific Ch

ang

e in

oil

dem

and

, m

illio

n b

pd

Non-OECD Pacific China


HPI 2011 FORECAST

materials, process control initiatives and environmental consider-ations continues to drive capital spending.

Maintenance spending nearly $65 billion. During tough times, reliability and uptime for facilities is a top priority for HPI companies. Unplanned outages are lost revenues during any time. But at the bottom of an economic cycle, lost production is the critical edge that could push a facility into insolvency. Worldwide HPI maintenance spending is forecast to approach $64 billion in 2011—an increase of $3 billion from projected 2010 spending. Maintenance expenditures are more proactive; HPI companies are more concerned about process-unit availability.

In 2011, spending for equipment and materials represents 40% of the maintenance budget. Labor costs account for remain-ing 60% of the maintenance budget. As more HPI companies review their balance sheets and downsized to cut variable costs, some companies will use more outsourced services.

CONSTRUCTIONAs shown in Table 3, the number of reported projects in the

2010 HPI Construction Boxscore increased under the economic pressure from the past 12 months. At present, 5,732 HPI projects are at various levels of development. Activity is present in refin-ing, petrochemical and gas processing industries. All surveyed regions show new project announcements from June 2009 to June 2010, as shown in Table 4. Even under these dire economic conditions, investment in new and existing HPI facilities contin-ues. Asia-Pacific and the Middle East continue to be hot beds of construction activity.

Time tables for projects are being extended to commission new production at the optimum entrance into the consumer market. Construction activity is ongoing, but more discipline will be applied to reign in costs from project overruns. Changes are anticipated to improve strategic supply-base relations for major HPI construction projects. In addition, better management in purchasing, scheduling, construction and site management will aid in controlling capital investment for HPI projects.

REFININGIn plain speak, developed (OECD) nations are still recover-

ing. The global refining industry was gravely impacted by this downturn. More important, the combination of new capacity and declining demand was the perfect storm to almost wipe out margins in 2009 and in the first half of 2010. And now, this industry must fight back. Nearly 70% of crude oil is refined into transportation fuels—gasoline, diesel, jet fuel, marine and loco-motive. Any changes in this market sector will directly impact the refining industry.

Besides consumer and business demand declines for trans-portation fuels, other factors are equally putting more pressure on the refining industry. Over the next 10 years, several forces

will reshape the global refining industry and the consumption of refined products. Here are several major game-changing trends that may adversely affect the global refining industry:

Biofuels and renewable substitutes. Biofuels gained popularity as a means to wean nations off of imported crude oil supplies and to support domestic agriculture industries. There is a “green” benefit attached with biofuels that is supported by environmental groups and governments. Many OECD nations have legislation on the books mandating increasing percentages of biofuels blended in transportation fuels. First-generation bio-fuels have not lived up to their hype; thus, a second generation of biofuels is being pressed into action.

Unfortunately for refiners, biofuels displaced crude oil-based refined products from the market. As the percentage of biofuels and renewables required in fuels increases, more spare capacity will emerge, thus complicating matters. Spare capacity, through construction of new units and/or displacement of refined products by alternatives, lowers utilization rates and margins for refiners. Demand destruction is a potential unintended consequence from the recession.

Energy efficiency standards. In addition to biofuels, new rules are mandating automobile manufactures to increase the miles-per-gallon travel by later-model vehicles. The Corporate Average Fuel Economy (CAFE) standards will increase from 27.3 mpg travel to 35.5 mpg beginning 2016. It will take time to turn the vehicle fleet over to newer vehicles. Unfortunately, in developed nations, the vehicle population will not grow dramatically as market saturation

TABLE 4. Worldwide HPI construction projectsArea June 2008 June 2009 June 2010

US 671 714 716

Canada 188 212 209

Latin America 458 530 607

Europe 1,153 1,261 1,283

Africa 192 215 231

Middle East 942 990 1,057

Asia-Pacifi c 1,425 1,551 1,629

Total 5,029 5,473 5,732

Table 3. Worldwide HPI construction projectsHPI sector June 2008 June 2009 June 2010

Petrochem/chem 1,676 1,837 1,889

Refi ning 1,564 1,692 1,751

Gas processing 1,127 1,196 1,266

Synfuels 87 98 108

All others 650 650 718

Total 5,104 5,473 5,732

Contribution of refining to US transportation fuel life-cycle GHG emissions.

FIG. 3

Oilextraction

Figure data: “Development of Baseline Data and Analysis of Life Cycle GreenhouseGas Emissions of Petroleum-Based fuels”, National Energy Technology Laboratory,Office of Systems, Analyses, and Planning; 2009; DOE/NETL-2009/1346.Source: HP, September 2009

Oiltransport

Oilrefining

Fueldistribution

80%

1%10%2%7%

Fuelcombustion

HPI 2011 FORECAST


occurs and the population grays. With greater CAFE requirements, less transportation fuels will be necessary.

Climate change and carbon regulations. This is a “wild card” subject. Europe is aggressively pursuing carbon poli-cies to control carbon dioxide (CO2) emissions from stationary and mobile sources. Unfortunately for refiners, carbon policy is a two-punch issue. Carbon reduction legislation will limit CO2 emissions from fired heaters and other combustion sources within the refinery. The second punch addresses CO2 tail-pipe emissions when transportation fuels are combusted by vehicle engines (Fig. 3). Pressure is on automobile and light- and heavy-duty truck manufacturers, as well as, refiners to solve tail-pipe emissions from mobile sources. Such directives open opportunities for electric vehicles and natural gas-powered vehicles to make inroads into the automobile population due to their low-environmental impacts.

Outlook. Energy demand drives economic growth. Over the last five years, crude oil demand has hovered around 85.8 million bpd, as shown in Fig. 1. Accordingly, global energy demand has stalled; but developing (non-OECD) nations continue to increase demand for crude oil over the same time. It is the developed nations that are stymied by recent economic events. Non-OECD nations will be responsible for further demand growth for energy.

From Fig. 4, the vehicle population is also changing. In the future, heavy-duty vehicle population will increase, thus increas-ing demand for diesel. Aviation demand will also increase beyond 2010. Changes in fuel product demand will affect the operations and configuration of refineries. The world is a “diesel-oriented” market. The exception is the US, which is the largest gasoline market. However, changing demand by consumers and growth in the transportation sector indicate a shift to diesel over gasoline in the US. New project expansions such as Marathon’s Garyville, Louisiana, refinery and Motiva’s Port Arthur, Texas, refinery are planned to increase ultra-low-sulfur diesel production to meet growing domestic demand.

Renewable mandates require substituting biofuels for gaso-line; thus creating surplus gasoline and refining capacity in the US. Europe’s refining industry is out of balance—too long on gasoline supplies and too short on clean diesel. This region relies on exports of gasoline and imports of diesel to balance transpor-tation fuel demand.

Asia-Pacific is the new center for new fuel demand as shown in Fig. 2. China and India will drive crude oil demand. The develop-ing middle class in both nations will increase demand for energy as well as products. China is pursuing joint venture and independent projects to develop their refining/petrochemical industries.

NATURAL GAS/LNG

Consumption. Natural gas prices have remained anemic due to a stronger dollar, higher oil prices, full inventories, overca-pacity and cutbacks in heavy manufacturing. With sustained lower prices, global natural gas consumption declined by 2.1% in 2009—the fastest decline on record.

With continued slow economic growth, the US decreased natural gas consumption by 1.5% from 2009. Worldwide, con-sumption decreased and was below average in most regions, except for the Middle East and Asia-Pacific. Russia accounted for the largest decline in global gas consumption, falling 6.1%. The biggest player in 2009 annual consumption was India, growing by 25.9%, with Brazil as a close second, increasing by 25.8%. The EU, with its continued efforts to reduce coal consumption, will continue its reliance on natural gas use; it experienced a 7% decrease in natural gas consumption for 2009 compared to an increase during 2008.

The Energy Information Administration (EIA) expects US natural gas consumption to increase by 3.5% for 2010, with a slight increase of 0.1% for 2011. Fig. 5 illustrates the US nat-ural gas consumption short-term outlook. For 2011, the EIA expects US natural gas consumption to decrease in all energy sectors except for industrial, which will increase by 1.7%. For 2009, global coal consumption was flat due to cheap natural gas and slow economic recovery. For 2010, the cold weather helped increase natural gas consumption in the electric power sector, along with low natural gas prices.

Global natural gas consumption is projected to increase—based on competitive energy prices, continuing environmental pressures and improved technologies. Global coal consumption for 2009 contracted 10.4%, however, with China accounting for the largest increase. The decrease in coal consumption stemmed from the recession and the competitive price of natural gas. Hydropower took over coal’s long standing as the fastest growing fuel for 2009.

Production. BP’s Statistical Review reported that, in 2009, global natural gas production fell by 2.1%, with Russia (–12.1%) and Turkmenistan (–44.8%) each having the largest declines recorded. For 2009, the US increased production by 3.5%, the largest increase for the past three years. The UK had a decrease in pro-duction, 14.1%. Production in the Middle East and Asia-Pacific increased—with India and Qatar having the largest increases, 28.9% and 16.3%, respectively. The EIA cut its domestic natural gas production growth estimate in 2009 and further increased the expected decline in demand as economic activity continues to slow. With persistent discussions concerning the climate, natural gas will continue its growth in electric-power production.

Global transportation demands by type, 1980–2030.

FIG. 4

0

10

20

30

40

Glo

bal

tra

nsp

orta

tion

dem

and

, m

illio

n b

pd

50

60

70

1980 2005 2030

Rail

Light dutyvehicles

Heavy dutyvehicles

Aviation

Marine

Source: ExxonMobil

Average growth/yr2005–2030, 1.3%


HPI 2011 FORECAST

In the US, new natural gas production is still increasing as new drilling starts have steadily increased. New technology primarily used for natural gas trapped in shale—such as the Barnett shale around Fort Worth, Texas, and the Marcellus shale in Pennsylva-nia—is the main reason that US production has increased. The Marcellus shale has an enormous volume potential and will be of great economic significance for the US. It will provide natural gas supplies to the high population areas of New Jersey, New York and New England. This transportation advantage will give Marcellus gas a distinct advantage in the marketplace, and this will have a positive impact on US natural gas supply stability.

International trade. For 2009, international trade in natural gas contracted 2.1% for 2009. Pipeline trade decreased 5.8% due to the decline in pipeline shipments from Russia and Canada. How-ever, global liquefied natural gas (LNG) trade increased by 7.6%. Shipments declined due to excess supply and low demand. Atlantic and Pacific basin LNG trade continues to integrate. In January 2010, US LNG imports more than doubled from last January, since cold weather improved prices and attracted incremental cargoes.

LNG provides a means to move supplies great distances where pipeline transport is not feasible, allowing access to natural gas from regions with vast production potential that are too distant from end-use markets. At present, the worldwide LNG industry has grown such that distance is only one of many factors that may influence future LNG project developments. Natural gas has always been difficult to transport, requiring processing to LNG or using newer gas-to-liquids (GTL) processing. New technologies, such as improved catalysts and economies-of-scale have lowered LNG expense considerably. This, coupled with countries wanting to decrease their carbon footprint, is finally beginning to fulfill the decades-old promise of LNG as a globally traded fuel.

In addition to environmental issues, the growing demand for natural gas is also being driven by economic and market factors that include energy diversification, energy security strategies and general economic conditions. The greatest growth is occurring for electric-power generation. Countries with large natural gas reserves are working to develop these resources for profitable export to consuming nations via pipelines, liquid petroleum gas (LPG)

transport, LNG cryogenic tankers and GTL projects. This growth is anticipated to come in the Middle East, Russia and non-OECD countries, where most of the reserves are located and are geographi-cally remote from the areas with the greatest demand growth.

PETROCHEMICALSIn 2010, the global petrochemical industry is still struggling.

This recession almost nearly destroyed demand for petrochemi-cal-based products, which are commonly used in daily life. High unemployment contributed to a free fall in demand for petro-chemical-based consumer products such as furniture, automobiles, appliances, packaging materials, computers, televisions, building construction materials, electronics, building insulation, etc. Global demand in ethylene, the building block petrochemical, decreased 7.1% in 2008; demand is rebounding at 5% in 2011.

But not all economies are on the same path for recovery in 2010. Again, Asia-Pacific nations, in particular Pacific non-OECD nations, will be responsible for major demand growth. In 2008, Western Europe and North America experienced demand declines for ethylene at 13.9% and 16.2%, respectively. Western European petrochemical producers report a 9% increase in pet-rochemical demand in 2010, but demand in this region is still below pre-2007 levels.

Previously, forecasters would estimate new ethylene demand growth as 1.6 times the domestic GDP. Unfortunately, most national GDPs were negative in 2009. There is some improve-ment in 2010. In mid-2010, the International Monetary Fund announced that the global economy should expand 4.3% in 2011—down from 4.6% in 2010. The US GDP should be 2.9%, while Europe will still struggle with a –1.3% in 2011. China and India will have more robust economies and GDP growth of 8% in 2011. These numbers do not include inventory destocking/stocking numbers.

New centers. Changing demand for petrochemicals and byproducts, and shifts in finished-goods manufacturing, now favor the Asia-Pacific region. In particular, China has emerged as the global factory for petrochemical-based consumer goods. Lower production costs have shifted many manufacturing jobs

US total natural gas consumption.FIG. 5

0.7

3.9

-4.4

3.5

-3.2

0.2

-1.4 -1.5

6.5

0.3

-1.5

3.5

0.1

-6

-4

-2

0

2

4

6

8

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

58

60

62

64

66

68

Source: EIA, Short-Term Energy Outlook, July 2010

Consumption

Annual growth

Forecast

Bill

ion

cu

bic

fee

t p

er d

ay

Ch

ang

e fr

om p

rior

yea

r, %

HPI 2011 FORECAST


to China. Yet, China cannot support its domestic demand for ethylene derivatives and it relies on imports.

The Middle East is emerging as the new “Gulf Coast” for pet-rochemical products. Lower-cost feedstocks provide operating cost advantages for Middle East-based ethylene units. The Middle East continues to increase its share of the global ethylene market with construction of new world-scale petrochemical facilities. Much of the new capacity is planned as export products, with much of the petrochemicals directed to China as well as Western Europe. Euro-pean producers cannot compete against the new Middle East world-scale units. Any demand increase in Europe will be met by imports.

More shake-out is anticipated for the global petrochemi-cal industry. The wave of ethylene capacity in the Middle East and China will create excess ethylene supplies that cannot be absorbed by chilled demand for products. The excess supplies depress utilization rates further—compounding profitability for older, less-energy efficient facilities (Fig. 6). North America and Western Europe are vulnerable to lower utilization rates, which erode plant profitability. More shake-ups are anticipated as new petrochemical capacity further floods the global market, and demand remains contracted from the aftershocks of this global recession. HP

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New ethylene capacity additions by regions, 2007—2014.FIG. 6

-4-2

0

2

4

6

8

10

12

14

2007 2008 2009 2010 2011 2012 2013 2014

Ethy

lene

cap

acity

add

ition

s,m

illio

n m

etric

tons

North AmericaMiddle EastSoutheast AsiaWest. EuropeNortheast AsiaOthers

Source: CMAI


HPINNOVATIONS


SELECTED BY HYDROCARBON PROCESSING EDITORS

[email protected]

New alternative technologies for oil spill cleanup

C.I.Agent Solutions, a global leader in solutions for fuel and oil spill cleanup and containment, exhibited at Clean Gulf 2010 and featured its latest innovative and alternative technologies for fuel and oil spill cleanup and containment that are used both for preparedness and response efforts. Clean Gulf 2010, the largest oil spill training event and exhibition in North America, was held in Tampa, Flor-ida, this past October.

According to C.I.Agent Solutions Founder and CEO Dan Parker, “Whether you insure marine vessels, own a fleet of workboats or run a marina, our marine-industry products help you contain and clean up hydrocarbon spills on fresh or salt water—including the sheen—for less time and money than the present dated methods.” Mr. Parker and his team spent the summer in the Gulf of Mexico as part of oil spill and recovery efforts from the Deepwater Horizon explosion.

C.I.Agent Solutions featured eight new products during the Clean Gulf 2010 con-ference, which included:

• Continuous low-level aquatic moni-toring (C.L.A.M.)—a state-of-the-art submersible extraction sampler using Environmental Protection Agency (EPA) approved solid-phase extraction (SPE) media to sequester pesticides, herbicides, PAH’s, TPH and other trace organics from water. C.L.A.M. can be used to sample urban water systems, rivers, monitoring wells, drinking water systems, watersheds and lakes, agricultural runoff, storm water and marine environments.

• EVAC filtration system—state-of-the-art filtration technology to remove sus-pended solids and light sheen from water discharge operations in vaults, manholes, elevator shafts, bilges, tanks and more. Its unique four-layer system adsorbs hydrocar-bons, removes large and fine sediment and polishes the water.

• Sheen machine (Fig. 1)—a self-con-tained system ideal for capturing hydro-carbon sheen in remote areas with limited access, such as creeks, streams and outfalls. This durable, lightweight and portable system can also be used in marinas and

harbors to capture and remove hydrocar-bon sheen before it impacts the environ-ment. Two Sheen machines have recently been used to aid the EPA and Enbridge Liquid Pipelines to prevent oil sheen from a pipeline leak near Marshall, Michigan, from reaching Lake Michigan.

• Tar Ball Catcher—attaches easily to any hard boom and will catch tar balls and other debris suspended in the water column. Once the tar balls are caught in the net, they either stay in the netting, or release and float to the water’s surface for capture and disposal. Tar Ball Catcher is custom made to meet site-specific require-ments and can be used in fresh or salt water with light to heavy current.

• Water Cannon —an effective spill response tool for applying C.I.Agent oil-solidifying polymers directly onto a hydrocarbon spill in fresh and salt water (Fig. 2). The Water Cannon’s unique design creates a vortex within the water jet to prevent the hydrophilic polymers from separating from the water during appli-cation, eliminating the possibility of the polymers becoming airborne. The Water Cannon is custom built to size, flow and pressure requirements and can be hand held or mounted.

• C.I.Agent, the company’s flagship product, is an environmentally friendly blend of food-grade polymers that solidi-fies hydrocarbons (sheen, gasoline, diesels and oil including crude) into a recyclable rubber-like mass. C.I.Agent is listed on the EPA NCP product schedule.


Lightweight PC endures harsh environments

Daisy Data Displays, Inc. (D3), indus-try leader in developing specialized and ruggedized computers, displays, and key-boards designed to endure harsh industrial and plant environments, has announced the release of its latest PC, the 4823CX Series (Fig. 3).

As HP editors, we hear about new

products, patents, software, pro-

cesses, services, etc., that are true

industry innovations—a cut above the

typical product offerings. This sec-

tion enables us to highlight these

significant developments. For more

information from these companies,

please go to our website at www.

HydrocarbonProcessing.com/rs and

select the reader service number.

A member of C.I.Agent Solutions demonstrates the Water Cannon.

FIG. 2

D3’s 4823CX Series PC. FIG. 3

Solid wall of gabion baskets protect the shoreline.

FIG. 1


HPINNOVATIONS

The durable, relatively lightweight PC is equipped with a 15-in. LED backlit LCD, glass-on-glass resistive touch screen and has the ability to endure extreme temperatures. Besides its sleek and por-table 20 lb body, other features include a low-power Intel Atom processor, as well as optional Bluetooth, GPS, speakers, cam-era, microphone, WiFi antenna, battery and charger. Battery options include either a 115/230-volt AC version or a 24-volt DC version. It is also rated NEMA 4X and FM approved, pending Division 2 and Zone 2 ATEX rating.

D3 unveiled its new PC at recent trade shows including Interphex in New York City and the Offshore Technology Confer-ence in Houston. There, the company was able to quote the machine for customers, and distribution began in June 2010. The 4823CX Series is essentially a new product in the industrial computer business with nothing else comparing to its small, sturdy, self-contained structure. Customer feed-back inspired D3’s innovation.

“We would go to trade shows and hear ‘We like your product, but it’s too heavy to carry around in the field,’” said D3 Gen-

eral Manager, Mike Hadaway. “There was a definite void in the market for a product this lightweight and rugged, so we filled it.”


CFD software used in LNG cryogenic power recovery turbine

The Cryodynamics division of Ebara International Corporation produces spe-cialized cryogenic liquefied gas pumps and turbine expanders. When Ebara’s liquid natural gas (LNG) complex, built for the Sultanate of Oman, went fully operational after three years in develop-ment, it incorporated the first submerged hydraulic turbine generators. Six turbines and critical components were developed for the Oman facility. These required in-depth analysis to minimize risks and com-ply with strict development requirements. Ebara used Agile Engineering Design Sys-tem (AEDS) turbomachinery software from Concepts NREC (CN) to perform essential turbine analyses.

“A major requirement was to make it as efficient as possible, increasing productivity of the liquefaction process, while recover-ing the fluid energy as electrical power,”

said Hans Kimmel, executive director of R&D for Ebaras–Cryodynamics division. “It was a completely new development with no prior art. We used CN’s computational fluid dynamics (CFD) software.”

Part of the challenge was testing effi-ciency before installation. The design included a variable speed unit, so mechani-cal analyses were required to satisfy rotor-dynamic aspects, avoid critical frequencies and comply with electrical requirements. Testing the units was done at Ebara’s manu-facturing facility in Sparks, Nevada.

Basic design information was used to construct a turbine stage computer model for analysis using CCAD from AEDS. An interactive and highly flexible geometry generator based on the Bezier-Bernstein polynomials, CCAD enabled estimates of blade row performance by means of invis-cid, two-dimensional streamline curvature analysis used to guide the runner redesign. CFD analysis enabled a complete assess-ment of the flow field through each turbine component. Performance was estimated by mass averaging the properties on planes at the inlet and exit of each component.

Based on CFD analyses, the runner

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HPINNOVATIONS


was redesigned in several steps to reduce or eliminate poorer flow features, and the return bend was redesigned. Significant improvement relied on increasing the axial length of the return bend.

A 10% increase in overall stage length was permissible and allowed the return bend to be increased by approximately 20% in axial length. CFD analysis of the redesigned return bend later showed that the stage efficiency increased by eight points to 89.4%.

Kimmel said, “Novel equipment can only be applied in LNG plants if the design is an extrapolation of existing designs and novel aspects are carefully reviewed and analyzed. The CN software made it possi-ble to perform the analysis needed in devel-oping the first-of-its-kind LNG cryogenic power-recovery turbine.”


Shaw adds two technologies to meet environmental regulations

Shaw Group Inc. has announced it has expanded its technology portfolio with the addition of two refining technologies designed to help refiners meet increas-

ingly stringent environmental regulations for cleaner gasoline. The two technolo-gies, More Iso-Paraffins (MIP) and Clean Gasoline and Propylene (CGP), reduce undesirable components, such as olefins, sulfur and benzene, from gasoline. The new technologies also increase the yields of premium components, such as iso-paraffins, for high-performance engines and propylene used to manufacture pet-rochemicals.

The technologies can be installed in either existing or grassroots fluidized cata-lytic cracking (FCC) units through modi-fications to the unit’s riser reactor section. The technologies provide operators with the flexibility to switch the desired opera-tion mode based on market demand, oper-ating either in maximum gasoline mode or increased propylene mode.

Shaw will market these technologies outside China on behalf of the developer, Sinopec’s Research Institute of Petroleum Processing (SINOPEC RIPP).

“Shaw is a leading FCC licensor, and we are recognized for our residual fluidized catalytic cracking (RFCC) and deep cata-lytic cracking (DCC) technologies,” said

Lou Pucher, president of Shaw’s Energy & Chemicals Group. “The addition of these two commercially proven technolo-gies will enable us to help oil refiners build or revamp more profitable and flexible FCC units that meet the challenges of new gasoline regulations and produce more propylene from heavy oils.”

Developed by SINOPEC RIPP in the late 1990s, the technologies were com-mercialized in 2002 in China. Since then, more than 30 units have been installed with capacities ranging from 0.44 to 3.0 million tons per year. Shaw has licensed SINOPEC RIPP’s DCC technology outside China since 1993. Shaw has also licensed SINO-PEC ’s catalyst cooling technology since the early 1990s.

“Shaw has demonstrated its ability to license, design and engineer our new tech-nologies in the world market,” says Dr. Jun Long, president of SINOPEC RIPP. “We believe the expansion of our alliance technology portfolio with Shaw will fur-ther elevate SINOPEC RIPP’s position as a leading refining technology research and development center.”




HPIN CONSTRUCTIONHELEN MECHE, ASSOCIATE EDITOR

[email protected]

North AmericaTechnip has been awarded an engineer-

ing, procurement and construction-support lump-sum contract by Valero Refining Co. for two flare-gas recovery units at its Port Arthur, Texas, refinery. Each unit involves modifying the existing flare, gas-compression and gas-treating systems to remove hydrogen sulfide. The recovered and treated gas will be returned to the refinery fuel-gas system.

Technip’s operating center in Hous-ton, Texas, will execute this contract, which is scheduled to be completed in the third quarter of 2011. The scope of work includes basic engineering, project manage-ment, detailed engineering, procurement, construction support, precommissioning and startup assistance. This project follows the successful execution of Technip’s front-end-engineering design.

After four years of continuous effort, Gov. Joe Manchin and TransGas Develop-ment Systems President Adam Victor, along with several state and local representatives, announced that TransGas Development Sys-tems has selected its engineering procure-ment contractor and technology provider for its coal-to-gasoline facility that will be built in Mingo County, West Virginia. This facil-ity will reportedly be the nation’s first. It will also be the largest of its kind in the world.

The project will be built by SK Engi-neering & Construction, and will use the technology of Uhde GmbH. It will convert regional coal into 756,000 gpd of premium-grade ultra-clean gasoline.

Praxair, Inc., has begun supplying BP’s refinery complex in Whiting, Indiana, with hydrogen from its new state-of-the-art hydrogen facility. The two steam-methane reformers have a total capacity of 200 mil-lion scfd. BP uses hydrogen to produce ultra-low-sulfur gasoline and diesel fuels. The facility was fully designed, engineered, procured and built by Praxair’s hydrogen engineering group.

South AmericaUOP LLC, a Honeywell company,

has announced that Petrobras has selected UOP to provide all of the process technologies for two new maximum

diesel refineries to be built in Brazil. UOP hydrocracking and hydrotreating technologies will be used to produce high-quality diesel fuel from Brazilian national crude oils at the two new refineries. Petrobras plans to construct a two-train 600,000-bpd facility in Maranhão, Brazil, to be known as Premium I, and a single-train 300,000-bpd facility in Ceara, Brazil, to be known as Premium II.

Basic engineering for the refineries is underway. Commissioning of the first train at the Premium I facility is planned in 2014, and the Premium II facility in 2017. Both facilities will use UOP’s Unicracking hydrocracking process and Unionfining hydrotreating process to upgrade feedstocks to ultra-low-sulfur diesel. Selective-Yield Delayed-Coking (SYDEC) technology, provided by Foster Wheeler USA, will also be used to maximize diesel production by converting the crude oil’s residue portion to an intermediate product used in diesel pro-duction. UOP will also serve as the front-end engineering design (FEED) contractor to provide a firm basis for the site’s pro-curement and construction. Design of the crude and vacuum systems in the refineries will be provided by Process Consulting Services, Inc., through an alliance partner-ship with UOP.

PDVSA and Eni have contracts for creating two Mixed Enterprises (Empresas Mixtas): PetroJunín, dedicated to develop-ing the Junín 5 Block, located in the Ori-noco Oil Belt, some 550 km southeast of Caracas, Venezuela, and PetroBicentenario, dedicated to constructing and operating a refinery in the area of the existing industrial coastal complex of Jose, Venezuela. Par-ticipation in both mixed enterprises will be PDVSA 60% and Eni 40%, according to the terms of the new hydrocarbon law of the Bolivarian Republic of Venezuela.

The new refinery will have a capacity of 240,000 bpd, plus the ability to pro-cess additional volumes of approximately 110,000 bpd of intermediate streams from other PDVSA facilities, which will provide additional value to the project. Eni will pay a bonus of $646 million. $300 million of this will be paid at the publication of the Mixed Enterprises’ contracts of incorpora-

tion. The balance will be paid in tranches, according to achievement of project mile-stones. Awarding of major contracts is expected in 2011 for early production, and in 2013 for full field development.

Burckhardt Compression (Brasil) Ltda. has finalized the delivery of two revamped process-gas compressors to the Petrobras RECAP refinery in Capuava, Brazil. The order included the relocation of deactivated compressors, and the redesign and revamp of the existing equipment to comply with Petrobas’ new operating conditions.

Braskem and INEOS Technologies have a strategic partnership for polyethylene (PE) technologies. Under this partnership agreement, Braskem can acquire licenses for Innovene S slurry and Innovene G gas-phase technologies to produce high-density PE and linear low-density PE in Braskem’s future petrochemical projects. In addition, Braskem and INEOS Technologies will jointly con-duct research and development programs for the slurry and gas-phase PE platforms.

The first petrochemical project to ben-efit from the partnership is the Etileno XXI project in Mexico. It forms the basis for the newly established Braskem IDESA S.A.P.I., a joint venture between Braskem and GRUPO IDESA. The two Innovene

Trend analysis forecastingHydrocarbon Processing maintains an

extensive database of historical HPI proj-ect information. The Boxscore Database is a 35-year compilation of projects by type, oper-ating company, licensor, engineering/construc-tor, location, etc. Many companies use the his-torical data for trending or sales forecasting.

The historical information is available in comma-delimited or Excel® and can be custom sorted to suit your needs. The cost depends on the size and complexity of the sort requested and whether a customized program must be written. You can focus on a narrow request such as the history of a particular type of project or you can obtain the entire 35-year Boxscore database or portions thereof.

Simply send a clear description of the data you need and you will receive a prompt cost quotation. Contact:

Drew Combs P.O. Box 2608, Houston, Texas, 77252-2608

Phone: 713-520-4409e-mail: [email protected]

Contrary to what you may think, we’re much more than a tube fi tting company.

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HPIN CONSTRUCTION

33

S plants that will form part of the Etileno XXI complex in Coatzacoalcos, Mexico, are scheduled to start up in January 2015. They will produce a full range of monomo-dal and bimodal high-density and medium-density polyethylene resins with a total nameplate capacity of 750 kty.

EuropeBecause of the persistently high demand

for polyamide 12, worldwide, Germany-based, Evonik Industries will continue to expand its laurolactam capacity further. This expansion represents a boost to the capacity increase taking place in Marl, Ger-many, which should be completed in the fourth quarter of 2010.

Headwaters Inc., in conjunction with Neste Oil Corp., has completed a success-ful plant trial for its proprietary HCAT hydrocracking technology at Neste Oil’s Porvoo refinery in Finland.

HCAT is a proprietary technology where a liquid precursor is introduced with the bottom-of-the-barrel feedstock, gen-erating a highly active molecular catalyst that improves the performance of existing ebullated upgrading units. Process enhance-ments, reported by Neste Oil following the trial, include higher residue conversion and less fouling of downstream equipment.

With the successful performance test in mid-October 2010, EDL Anlagenbau Gesellschaft mbH, Leipzig, Germany, a 100% subsidiary of the Vienna-based Pörner Group, completed the revamp of crude-oil-distillation unit No. 4, at the Schwechat refinery, within the stipulated budget and time. The project, worth approximately €20 million, included modernization of the dis-tillation unit’s lower circulating pumparound during normal plant shutdown.

EDL’s contract, awarded by OMV Refining & Marketing GmbH, was to per-form detail engineering, procurement and site-management services. The objective was to reduce the unit’s corrosion rate by lower-ing the temperature. This required extensive process-related modifications of the main column, as well as replacement of pipes, heat exchangers and control instruments.

CB&I Lummus has a contract for FEED services for the Shtokman LNG storage and loading facility at the seaport in Terriberka in the Murmansk region of the Russian Federation. The seaport is part of the Shtokman Gas-Condensate Field

Development Project developed by Gaz-prom Dobycha Shelf LLC. CB&I’s con-tract, which is scheduled for completion in 2011, was awarded by Giprospetsgas JSC, the project general designer. The contract value was not disclosed.

CB&I’s project scope includes concept and FEED development of the LNG stor-age and loading facility, including multiple 160,000-m3 full-containment LNG storage tanks, and the associated process-piping

and loading facilities. Concept and FEED development will provide the project schedule and cost estimates for the engi-neering, procurement and construction (EPC) phase. CB&I will also prepare the Russian design dossier (Proyekt) in accor-dance with regulatory requirements.

AfricaHyundai Heavy Industries Co. Ltd.

(HHI) held a naming ceremony for the



HPIN CONSTRUCTIONUsan FPSO, reported to be the world’s largest floating production storage and offloading facility. The Usan FPSO can refine 160,000 bpd of oil and 5 million m3

of gas per day. It has storage for 2 million bbl of oil. The facility is 320-m long, 61-m wide, 32-m high and weighs 116,000 tons.

The $1.7 billion FPSO was ordered by Total in February 2008. After trial runs in Ulsan, South Korea, the Usan FPSO will sail out for the Usan Field at the end of March 2011. The Usan Field is located 100 km south of Port Harcourt, Nigeria.

Middle EastAxens (Performance Programs) has

delivered a process operations simulator (POS) to Aromatics Oman LLC for its ParamaX complex that started up at the beginning of 2010. The POS integrates all of the complex’s units. The simulations are based on PRO/II comprehensive steady-state process-simulation software developed by Invensys Operations Management.

The ParamaX technology suite, imple-mented in Oman, is composed of pro-cesses, such as naphtha hydrotreating, Aromizing, Morphylane, Eluxyl, XyMax and TransPlus.

Uhde is in charge of the basic engi-neering for the Morphylane process, while Axens ensures basic engineering for the other ParamaX technologies, as well as the integrated package.

SK E&C has won the first overseas communication contract exclusively, worth $34 million, to build a communication system in Qatar in the Middle East. This project is to construct a communication system between oil refineries and petro-chemical plants in the Dukhan oil field, located 95 km to the west of Doha, the capital of Qatar. Qatar Petroleum placed this order, which has a construction period of 30 months, starting at the end of Octo-ber 2010 and finishing in April 2013.

His Highness, The Emir of Qatar, Sheikh Hamad Bin Khalifa Al Thani, officially inaugurated Q-Chem’s second plant, Q-Chem II. This plant will pro-duce 350,000 metric tpy of high-density polyethylene (HDPE), increasing the total HDPE capacity of Qatar Chemical Co. Ltd. by more than 75%. It will also produce 345,000-metric tpy of normal alpha olefins (NAOs), making it the first facility in the Middle East to produce these compounds. The Q-Chem II HDPE and NAO expan-

sion increases the overall derivatives product capacity at the Mesaieed site by 140%.

Both HDPE and NAO will be produced using proprietary technologies licensed by Chevron Phillips Chemical Co. LP.

The EPC contract for the project was won by a consortium of TECNIMONT S.p.A. and Daewoo Engineering and Construction Co. Ltd.

CB&I has been awarded a contract, val-ued in excess of $60 million, by Daewoo Engineering and Construction Co. Ltd., for the construction of several storage tanks for the Ruwais refinery expansion project in Abu Dhabi. Takreer, a subsidiary of ADNOC, is expanding the refinery to add 400,000 bpd in capacity.

Asia-PacificSinopec Zhenhai Refining & Petro-

chemical Co. Ltd. (ZRCC) has launched a new ethylene oxide/ethylene glycol (EO/EG) plant in China using the METEOR EO/EG process, licensed through The Dow Chemical Co. The ZRCC plant, which first started up in April 2010, is the second plant in China to use the METEOR process. The first, operated by Sinopec-SABIC (Tian-jin) Petrochemical Co., began production in February 2010. Aker Solutions assisted on the preparation and expansion of the process-design package, while SINOPEC Shanghai Engineering Co. Ltd. (SSEC) completed the facility’s detailed engineering.

Univation Technologies LLC has announced that PuCheng Clean Energy Chemical Co. Ltd. has selected Univation’s UNIPOL PE process for a 300,000-tpy polyethylene high-density/linear-low-den-sity swing plant. The facility will be fed by ethylene from a combination of coal-to-methanol and methanol-to-olefins technol-ogy. The facility will be located in Shaanxi Province, People’s Republic of China, with a planned startup in 2013.

Celanese Corp. intends to construct manufacturing facilities in China and the US to use advanced technology for producing ethanol for chemical applications and other industrial uses. Following necessary approv-als, Celanese plans to construct one, and pos-sibly two, industrial ethanol complexes in China to serve the fast-growing Asia region.

Initial production capacity of each com-plex is expected to be approximately 400,000 tpy. The company could begin industrial ethanol production within 30 months after

project approvals. The China units would utilize coal as the primary raw material.

Celanese also intends to build an approx-imately 40,000-ton industrial ethanol pro-duction unit at its Clear Lake, Texas, facility for either internal use or merchant demand. The unit will also support continuing tech-nology development efforts over the next several years. Following approvals, unit con-struction is anticipated to begin in mid-2011 and be completed by the end of 2012. The Clear Lake facility would use natural gas as its primary raw material.

Foster Wheeler AG’s Global Engi-neering and Construction Group has been awarded a contract by Perusahaan Gas Negara (PGN) to provide project man-agement consultancy (PMC) services for a new floating LNG receiving terminal (the Medan floating LNG terminal facility) to be built in Medan, North Sumatra, Indonesia.

The Foster Wheeler contract value for this project was not disclosed. The com-pany’s scope of work includes technical assistance through the initial phase of the project’s development; conceptual design of the terminal; basic subsea and onshore pipeline design; preparation and issue of an invitation to bid for engineering, procure-ment and construction (EPC); EPC bid evaluations; preparation of the EPC con-tract; and support to PGN in EPC-contract negotiation. Foster Wheeler will fulfill the role of owner’s engineer during the project’s EPC phase through to terminal startup.

Alfa Laval has received an order for Alfa Laval Packinox heat exchangers to be used in a refinery in India. The order value is about SEK 50 million, and delivery is scheduled for 2011. The heat exchangers will be used in a catalytic process to remove sulfur from refined diesel.

Neste Oil has started up what is said to be the world’s largest renewable-diesel plant in Singapore. Production of NExBTL renewable diesel will be ramped up on a phased basis. The plant was completed on-schedule and on-budget, and marks a major step forward in Neste Oil’s clean traffic fuel strategy. The Singapore plant has a capacity of 800,000 tpy and cost around €550 mil-lion to build. Neste Oil has a similar-sized facility under construction in Rotterdam, The Netherlands, which is due to be com-missioned in the first half of 2011. HP

Expanded versions of these items can be found online at HydrocarbonProcessing.com.


HPI CONSTRUCTION BOXSCORE UPDATE Company City Plant Site Project Capacity Unit Cost Status Yr Cmpl Licensor Engineering Constructor

AFRICA Angola Sonangol Lobito Lobito Refinery 200 Mbpd U 2012 KBR Morocco SAMIR Mohammedia Mohammedia Bitumen 270 Mtpy U 2011 Porner Porner Morocco SAMIR Mohammedia Mohammedia Storage, Tank (1) 5.5 Mm3 U 2011 Porner Porner Morocco SAMIR Mohammedia Mohammedia Storage, Tank (2) 5.5 Mm3 U 2011 Porner Porner

ASIA/PACIFICAustralia Santos\PETRONAS JV Queensland Bowen-Surat Basin LNG EX 1.5 Mtpy 750 U 2011 Total India Mangalore Rfg & Petrochemicals Mangalore Mangalore Desalter, 2- Stage 83200 bpd U 2011 Mackenzie Hydrocarbons Mackenzie Hydrocarbons Indus Projects LimitedIndia Essar Oil Ltd Vadinar Vadinar Refinery EX 375 bpsd U 2011 ABB Lummus Simon Carves |TCE EssarJapan Cosmo Oil Co Ltd Yokkaichi Yokkaichi Distillation, Crude 50 bpd C 2010 Singapore ExxonMobil Jurong Jurong Hydrotreater, Diesel 56600 bpd P 2014 South Korea S-Oil Corp Ulsan Ulsan Kerosene 44600 bpd U 2011 Mackenzie Hydrocarbons Vietnam Petrovietnam Vung Tau Vung Tau Carbon Dioxide Recov 250 t/a 27.17 C 2010 MHI Samsung Eng Samsung Eng

CANADASaskatchewan Consumers Coop Refineries Regina Regina Refinery EX 100 bpd 107 U 2012 Colt Worley Parsons (CWP) Veco |Mustang| CWP Veco |CWP

EUROPEAustria OMV AG Schwechat Schwechat Distiller, Crude (4) BY 0.3 Mbpd 28 C 2010 Lurgi Lurgi Greece Hellenic Petroleum SA Thessaloniki Thessaloniki Refinery EX 70 bpsd 198 E 2010 Foster Wheeler Italiana Greece Hellenic Petr AE Thessaloniki Thessaloniki Reformer, Cat RE 15 Mbpd U 2011 EMRE Asprofos|EMRE

LATIN AMERICABrazil Petrobras Ceara Ceara Unicracking 300 bpd U 2017 Honeywell UOP Honeywell UOPBrazil Petrobras Maranhao Maranhao Unicracking 600 bpd U 2014 Honeywell UOP Honeywell UOPCuba PDVSA Matanzas Matanzas Refinery, Heavy Ends 150 bpd 4300 P 2015 Ecuador Refineria del Pacifico-CEM El Aromo El Aromo Refinery 300 bpd 12500 P 2013 PGN Trinidad Petrotrin Pointe-a-Pierre Pointe-a-Pierre Diesel, ULSD (1) 40 Mbpd 220 U 2012 Lummus Technology Samsung Eng Venezuela Eni SpA Undisclosed Orinoco River Basin Refinery 350 bpd 9000 P 2016

MIDDLE EASTQatar Q-Chem II (JV Qatar Petr/Chevron Mesaieed Mesaieed Polyethylene, HD 350 Mtpy 1300 C 2010 Chevron Phillips Daewoo Eng|Tecnimont Daewoo Eng|TecnimontSaudi Arabia SABIC Al Jubail Al Jubail Air Separation Unit (1) 3.5 t/a 300 U 2011 Air Products Samsung Eng|Air Products UAE Borouge III Ruwais Ruwais Polyethylene, LD 350 Mtpy 400 E 2013 Tecnimont Samsung Eng UAE Borouge III Ruwais Ruwais Polypropylene (1) 480 Mtpy 1255 E 2013 Tecnimont Samsung Eng UAE Borouge III Ruwais Ruwais Polypropylene (2) 480 Mtpy 1255 E 2013 Tecnimont Samsung Eng

UNITED STATESFlorida Algenol Biofuels Lee Lee County Biorefinery, Ethanol 100 Mgpy 59 F 2011 Dow Chem Louisiana Sasol Lake Charles Lake Charles Ethylene Tetramerisation 100 m-tpy P 2013 Mississippi Chevron Pascagoula Pascagoula CCR 55 bpd 500 U 2010 Texas BP Amoco Chemicals Chocolate Bayou Chocolate Bayou Ethylene (2) 1.8 m-tpy M 2010 INEOS Virginia Western Refining Yorktown Yorktown Refinery EX 70 bpd A 2010

See http://www.HydrocarbonProcessing.com/bxsymbols for licensor, engineering and construction companies’ abbreviations,along with the complete update of the HPI Construction Boxscore.

THE GLOBAL SOURCEFOR TRACKING HPICONSTRUCTION ACTIVITY

BOXSCORE DATABASE ONLINE

For more than 50 years, Hydrocarbon Processing magazine remains the only source that collects and maintains data specifi cally for the HPI community, publishing up-to-the-minute construction projects from around the globe with our online product, Boxscore Database. Updated weekly, our database helps engineers, contractors and marketing personnel identify active HPI construction projects around the world to:• Generate leads • Market research • Track trend analysis • And, decide future budget planning.

Now, we’ve made our best product even better! Enhancements include:• Exporting your search results to Excel so you can compile your research • Delivering the latest updated projects directly to your inbox each week • Designing customized construction reports for your company using our 50 years of archived projects.

For a Free 2 -Week Trial, contact Lee Nichols at +1 (713) 525-4626, [email protected],or visit www.ConstructionBoxscore.com


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GAS PROCESSING DEVELOPMENTS SPECIALREPORT


Consider different alternatives for enriching lean acid gases New developments improve operation of Claus sulfur recovery units

B. ZARENEZHAD, Ministry of Science, Research and Technology, Semnan University, Iran

L ean acid-gas enrichment processes can be used to upgrade low-quality offgas from treating units to higher-quality Claus plant feed or to smaller volume streams that are suitable for

reinjection. The process objective is minimizing hydrogen sul-fide (H2S) leaks into the system’s vent gas, thus producing a gas enriched in H2S to the greatest extent possible.

Designing and operating acid-gas enrichment plants are highly sensitive for a number of parameters, including lean-solvent tem-perature (a serious constraint in the Middle East). Other param-eters are feed gas, including H2S/carbon dioxide (CO2), choice of tower internals type, number of contact trays, and solvent selection.

Managing acid gases. For acid gas feeds with an H2S con-centration greater than 50%, a reaction furnace temperature in excess of 925°C (1,700°F) can be achieved using the simple straight-through Claus process. However, if the acid-gas H2S concentration is significantly lower than 50%, the minimum required reaction furnace temperature of 925°C (1,700°F) may not be attainable without an upstream acid-gas enrichment unit to increase the H2S concentration of the Claus plant feed gas.

The required reaction furnace temperature is a function of acid-gas contaminants. Fig. 1 shows the reaction furnace theoreti-cal adiabatic flame temperature as a function of the H2S content in the acid-gas feed for a straight-through Claus plant configura-tion. The two horizontal dashed lines represent the tempera-ture targets required to completely destroy benzene, toluene and xylenes (BTX) and straight-chain hydrocarbons.

As shown in Fig. 1, the minimum flame temperature required to destroy BTX and heavy hydrocarbons cannot always be maintained. Aromatics (BTX) cannot be destroyed if the acid-gas H2S concen-tration is less than 60%, and paraffinic heavy hydrocarbons cannot be destroyed if the acid-gas H2S concentration is less than 50%.

Techniques such as supplemental fuel-gas firing can raise the reaction furnace temperature. However, supplemental fuel-gas firing introduces a number of negative factors.

First, there is a decrease in overall sulfur-recovery efficiency with supplemental fuel firing. This is mainly due to the forma-tion of significant amounts of undesirable byproducts such as carbonyls (COSs) and CS2. In addition, the water and inert gases produced by combustion lead to less than a favorable Claus equi-librium, which decreases the overall sulfur-recovery efficiency. In addition, equipment sizes must be larger to handle the higher gas flow that results from co-firing with fuel gas. Finally, fuel-gas supplemental firing usually requires more operator attention to ensure that coke formation does not occur.1,2

Preheating the acid gas and/or the combustion air streams prior to being fed into the reaction furnace is another option for increasing the reaction furnace temperature. The maximum reaction furnace temperature increase that can be achieved by preheat depends on the heating medium used, but is limited to about 60°C to 90°C (110°F to 165°F). Preheating increases sulfur plant capital and operating costs and increases the total pressure drop across the unit.

Oxygen enrichment. Oxygen enrichment is another process option that can effectively increase the reaction furnace tem-perature. However, depending on the location of the facility and the quantity of oxygen needed, oxygen enrichment may be prohibitively expensive if an inexpensive oxygen source is not readily available.

With the advent of selective amine treating systems, the H2S concentration of a Claus plant acid-gas feed stream can be increased by rejecting CO2 and other contaminants. Selective amine treating systems can also be used to increase the feed gas H2S concentration of existing Claus sulfur plants with the fol-lowing advantages: 1–3

• No impact on the reaction furnace combustion air require-ments

• No impact on sulfur plant capacity• Stable operation in the reaction furnace• Achievable required temperature for destruction of contami-

nants such as BTX, ammonia and cyanides• Wide range of acid-gas concentrationsNew technology has recently been developed that integrates

an acid-gas enrichment unit with the downstream tail gas treating

BTX

Straight-chain HC

2000 20 40

H2S content in feed gas, %60 80 100

400

600

800

Fla

me

te

mp

era

ture

, °C

1,000

1,200

1,400

Reaction furnace adiabatic flame temperature vs. acid-gas H2S content.

FIG. 1

GAS PROCESSING DEVELOPMENTSSPECIALREPORT

38

unit. This technology utilizes a special “double-absorption” design to enrich the acid gas. The process can be designed to process acid gas with an H2S concentration below 10% and achieve an overall sulfur recovery that exceeds 99.9%.

Acid-gas enrichment technology. The process is designed to selectively absorb H2S from lean acid gases that could contain less than 10% H2S, such as sour natural gas, refinery gas, synthesis gas or other sour CO2 streams to produce a high-quality acid gas with an H2S concentration up to 75%. This process can be used with various licensed selective amine treating technologies includ-ing formulated MDEA and proprietary selective treating solvents.4 The technology can also include a third-stage absorber with an integrated Claus tail-gas unit that uses a common regenerator.

Lean acid gas contains significant amounts of inerts such as CO2. Carbon dioxide lowers the net heating value of the acid gas and also reduces the concentration of sulfur dioxide (SO2) and H2S in the reaction furnace, making sulfur conversion more difficult. Dilute acid-gas feeds often contain contaminants such as ammonia and aromatics (BTX) that must be destroyed in the reaction furnace to protect downstream catalyst beds from fouling. The low-heating value of dilute acid-gas streams makes the com-plete destruction of these objectionable components difficult.5The minimum temperature for effective operation of the reaction furnace on “clean” acid gas should be above 925°C (1,700°F). In extreme cases, when the H2S content in the acid gas falls below 10%, the minimum reaction furnace temperature may become impossible to attain and additional processing steps must be used to effectively convert the H2S to elemental sulfur. In addition, the dilution effect of CO2 in lean acid gases will increase the size of the sulfur-recovery unit (SRU) as the plant size is controlled by the total volumetric flow of acid gas. This, in turn, will significantly increase the cost of the SRU.

When the acid gas is too diluted in H2S, a selective absorption technique may be used to enrich the acid gas prior to entering the Claus unit. By selectively absorbing H2S from the acid gas and then stripping the rich solvent, two gas streams are produced. The gas passing through the absorber is primarily CO2. This stream is sent to an incinerator for conversion of trace amounts of H2S to SO2 prior to discharge to the atmosphere. The gas stream leaving the regenerator is acid gas enriched in H2S. This stream can be processed in a conventional Claus unit.

Other options. Another selective treating application is in the processing of tail gas from a Claus SRU. The sulfur recovery effi-ciency of a third-stage conventional modified Claus unit is ther-modynamically limited to about 97%. A common practice that is used to comply with stringent sulfur emission environmental regulations is to convert the sulfur compounds in the Claus unit tail gas, such as COS and SO2, to H2S using hydrogenation and hydrolysis. The H2S is then removed from the converted tail gas and recycled back to Claus sulfur plant. This configuration can achieve sulfur recoveries of up to 99.9%.

Amine-based solvents capable of selectively removing H2S are used in these processes. These processes are based on MDEA or on sterically hindered amines that react rapidly with H2S and slowly with CO2. Typically, these processes concentrate H2S by a factor of three to five.

The following describes the double absorption acid-gas enrich-ment and the integrated double-absorption sulfur-recovery pro-cesses. These processes and configurations were developed to increase the H2S content of lean acid-gas streams.

Double absorption acid-gas enrichment process. The double-absorption process can be used as a stand-alone pro-cess to improve the quality of the acid gas from conventional

Acid gas toincineration To sulfur plant

Feed gas

P-1

P-3

P-2

E-2E-1

E-3V-1V-3

V-4

V-2

1

419

1011

12

6

7

58

2

2021

2324

14

17 18

9

1615

13

3

22

E4

Double-absorption acid-gas enrichment process. FIG. 2

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acid-gas removal units. This process recycles a portion of the acid gas to a second absorber to concentrate the H2S. Fig. 2 shows the basic configuration of the double-absorption process.

The acid-gas feed stream enters the unit and is scrubbed in the first amine absorber, V-1, with a lean amine stream 2. The solvent typically consists of 40% to 50% MDEA, although other solvents, such as a sterically hindered amine can be used. The amine absorber generally consists of 12 to 18 trays. About 85% to 90% of the feed gas CO2 is rejected in stream 3. The rich-solvent stream 4 exits the bottom of the first absorber and combines with the rich solvent from the second absorber, V-2, forming stream 6.

The combined stream is pumped and heated with the lean/rich exchanger, E-1, using the heat content of the lean solvent from the regenerator, V-3. The regenerator operates at a slightly higher pressure than the absorber. This allows recycling of a portion of the acid gas without using a compressor.

The heated stream enters the top of the regenerator, which consists of 20 to 22 stripping trays and a wash section. Alterna-tively, other contacting devices, such as packing, can be used. The acid gas in the rich solvent is stripped with heat applied at the bottom reboiler, E-2, producing overhead stream 9 and a lean solvent, stream 10.

The lean solvent is pumped and cooled in the lean/rich exchanger, E-1. The lean solvent is further cooled in E-3. Air or cooling water can be used as the cooling medium. The lean amine should be cooled as much as possible, as cooling favors the selec-tive absorption of H2S, thereby increasing the H2S selectivity. The cooled lean amine is split into two portions, stream 2 and stream 22, which are fed into the first absorber, V-1, and the second absorber, V-2, respectively.

The overhead vapor from the regenerator, stream 9, is cooled in the overhead condenser, E-4. Liquid in the stream is separated in the reflux drum, V-4. The liquid stream, which is mostly water, is pumped and used to reflux the regenerator. The enriched acid gas is split into two portions, stream 17 and stream 18. Stream 17 is routed to the second absorber, V-2, for further enrichment and stream 18 is sent to the SRU.

The flow ratio of stream 17 to stream 14 ranges from 25% to 75%, depending on the H2S concentration in the feed gas. For a low H2S-content feed gas, a higher flow ratio of possibly 75% may be necessary. The ratio can be reduced to less than 25% when the feed gas contains a higher H2S concentration. For most applications, acid-gas enrichment to about 75% H2S can be achieved. In addition, over 90% of the hydrocarbons and BTX components can be rejected with the CO2 stream. The H2S enrichment and the absence of BTX and heavy hydrocarbons in the enriched acid gas are highly desirable for good performance of the Claus SRU.5,6

Furthermore, depending on the feed-gas composition and acid-gas loading of the semi-lean solvent, the overall circulation rate can be reduced by splitting the semi-loaded rich solvent stream 7 from the first absorber into two separate streams. One stream can be cooled and reused for absorption in the second absorber V-2. The other stream, consisting of semi-lean rich solvent from the first absorber, which is still unloaded in terms of its H2S content, can be fed to the lower section of the second absorber for bulk H2S removal. The remaining semi-lean solvent can then be sent to the regenerator, V-3, for solvent regeneration. Fig. 3 shows the configuration for this option.

Integrated double-absorption acid-gas enrichment/sulfur recovery process. The double-absorption acid-gas enrichment

configuration can be integrated with the tail-gas unit to reduce the total project cost. The semi-lean solvent from the tail-gas unit, which is unloaded at the upstream absorber conditions, can be reused to reduce the overall solvent circulation while eliminating a dedicated regenerator. With this option, a single regenerator can be used to regenerate the rich-solvent streams from both the acid-gas enrichment and the tail-gas units.

Fig. 4 shows a configuration where acid-gas enrichment is integrated with the tail-gas treating unit. The combination of the enrichment unit with a tail-gas absorber processing the tail gas from a Claus unit can achieve over 99.9% total sulfur recovery even when the feed gas H2S concentration is low.

Acid gas toincineration To sulfur plant

Feed gas

P-1

P-3

P-2

E-2E-1

E-3

E-5

V-1V-3

V-4

V-2

1

419

1011

12

6

7

5825

26

2

20

21

2324

14

17 18

9

1615

13

3

22

27E4

Double-absorption acid-gas enrichment process with rich-solvent splitting.

FIG. 3

Hydro-genationquench

unit

Acid gas toincineration

Feed gas

P-1

P-4

P-3

P-2

E-2E-1

E-3V-1V-3

V-4

V-2V-5

1

419

1011

12

6

7

5836

35

32

2

2021

34

31

332324

30 18

14

17

9

1615

13

3

22

35

Clausunit

E4

Integrated double-absorption acid-gas enrichment/sulfur recovery process.

FIG. 4



In this configuration, a two- or three-stage Claus SRU is used to process the enriched acid gas. A conventional modified Claus SRU would require more than three stages and other various additional processing steps to achieve at best, 99% sulfur recov-ery. This integrated tail-gas treating configuration significantly reduces the sulfur plant energy requirement and improves sulfur-recovery efficiency while requiring less capital investment than a conventional design.

The effluent from the Claus unit, which contains trace quan-tities of H2S, SO2 and other sulfur compounds, is processed in the hydrogenation unit. The hydrogenated gas is quenched and extra water is condensed and removed prior to routing the gas to the tail-gas absorber, V-5. Lean amine is supplied from the lean-amine header. Effluent from the tail gas absorber, which contains environmentally acceptable levels of H2S, can, depending on envi-ronmental regulations, either be vented directly to the atmosphere or routed to an incinerator for disposal.6, 7

The rich amine from the tail-gas absorber is pumped and combined with the rich-amine streams from the first and sec-ond absorbers. The combined stream is heated in the lean /rich exchanger and fed to the common regenerator. Depending on the actual feed gas conditions and sulfur-recovery requirements, the semi-loaded solvent, stream 35, from the tail gas absorber, V-5, can be re-used in the second absorber, V-2. This configura-tion (option 1) as shown in Fig. 5, reduces solvent circulation and the solvent regeneration duty. With this configuration, the incremental amount of solvent used in the tail-gas absorber can be reduced, thus improving process economics while maintaining high sulfur-recovery efficiency.

Depending on the acid-gas composition and the semi-rich solvent loading, another option, shown in Fig. 6, can be used to further reduce the total solvent circulation rate and solvent regeneration duty. This configuration re-routes a portion of the semi-loaded rich solvent stream 7 from the first absorber, V-1, to the second absorber, V-2. The stream is cooled prior to entering the lower section of the second absorber, providing a cost-effective means for processing lean acid-gas feeds.

Optimization options. Several acid-gas enrichment process configurations and various options for integrating sulfur recovery with tail gas treating are presented here. The double-absorption process and various configuration options effectively produce acid-gas enriched in H2S from a lean acid- gas feed. Acid gas can be enriched from less than 7% to over 75% H2S. The various configurations also allow removal of hydrocarbons and BTX that are known to interfere with SRU operation. Furthermore, a CO2 stream with environmentally acceptable levels of H2S can be pro-duced from the absorbers for disposal by incineration. When inte-grated with Claus and tail-gas treating units, the process is capable of reducing the number of Claus reaction stages and can achieve over 99.9% total sulfur recovery. The double-absorption process also solves the problems of low H2S content and low acid heating value by providing a Claus plant feed with a high H2S content. HP

LITERATURE CITED 1 ZareNezhad, B. and N. Hosseinpour, Applied Thermal Engineering, Vol. 28, Issue 7, May 2008. 2 ZareNezhad, B., Hydrocarbon Processing, October 2008, pp 109–115. 3 ZareNezhad, B., Research Report 1342B, Petroleum Ministry, November 2008. 4 ZareNezhad, B., Hydrocarbon Processing, February 2009, pp. 63–72. 5 Chow, T. K., C. H. Lawrence, J. A. Gebur and V. W. Wong, Canadian International Petroleum Conference 55th Annual Technical Meeting, Calgary, Canada, 2004. 6 Clarke, D., J. Iyengar, M. Al-Khaldy and S. Summers, 51st Annual Gas Conditioning Conference, Oklahoma, 2001. 7 Chow, T. K, J. A. Gebur, and V. W. Wong, World Petroleum Congress, Second Regional Meeting, Doha, Qatar, 2003.

Hydro-genation

unit


Feed gas

P-1

P-4

P-3

P-2

E-2E-1

E-3V-1V-3

V-4

V-2 V-5

1

419

1011

12

6

7

5836

32

2

2021

34

31

332324

30 18

14

17

9

1615

13

3

22

35

Clausunit

E4

Integrated double-absorption acid-gas enrichment/sulfur recovery process (option 1).

FIG. 5

Hydro-genation

unit


Feed gas

P-1

P-4

P-3

P-2

E-2E-1

E-5

E-3V-1V-3

V-4

V-2 V-5

1

419

1011

12

6

7

5836

74

75

322

20

34

31

332324

30 18

14

17

9

1615

13

3

22

35

Clausunit

E4

Integrated double-absorption acid-gas enrichment/sulfur recovery process (option 2).

FIG. 6

Dr. Bahman ZareNezhad is an academic professional mem-ber of the Ministry of Science, Research and Technology in Iran. His research activities are mainly focused on advanced oil refining and gas processing technologies, tail-gas treatment, sulfur recovery and NGL extraction processes. Dr. ZareNezhad has published several technical

and research papers in international journals and has presented several technical courses regarding oil and gas industries. He has 22 years of varied experience in research, process engineering, project management and technology development, and is a consultant for several oil and gas companies. Dr. ZareNezhad holds a PhD in chemical engineering from the University of Manchester Institute of Science and Technology (UMIST) in England.



Avoid condensation-induced transient pressure waves Case studies give an indication as to probable causes for water hammer

G. MANI, BP Canada Energy Co., Calgary, Alberta

C ondensation-induced water hammer is a commonly occur-ring phenomenon in steam and condensate systems. In steam/condensate systems, condensation-induced water

hammer occurs when steam bubbles come in contact with, or are encapsulated in, subcooled condensate and then loses heat and condenses rapidly. This creates a low-pressure zone into which condensate moves rapidly. The resultant collision creates a pres-sure wave that reverberates through the body of condensate. The pressure developed from the collision can be derived from the momentum balance and can be written as follows:

P = ρV2

where:P = Pressureρ = Liquid densityV = Condensate velocityThe velocity can be as high as sonic velocity, i.e., the velocity of

sound in the condensate. For steam/condensate systems, this tran-sient pressure can be high enough to create catastrophic damage to piping. The velocity and consequently the pressure developed is a function of the following:

• Steam pressure• Condensate temperature• Bubble size• Quantity of noncondensable gasesDirectionally, higher steam pressure,

lower condensate temperature and higher bubble size favor development of higher-pressure transients. The noncondensable gases reduce the transient pressure due to their presence in the low pressure zone.

For hydrocarbon systems, condensation induced transient pressure waves similar to water hammer in steam systems do not occur often. This is because the fluids are generally multicomponent hydrocarbon mixtures and the sudden collapse of bubbles does not occur. In addition, flow regimes where vapor bubbles can be enclosed in sub-cooled liquid are generally avoided in the design. However, in one plant, there were two cases of condensation-induced transient pressure wave problems in relatively pure component service (~97% propane) that will be described in greater detail.

Case 1: Propane rundown system. The propane fraction-ation and rundown system is illustrated in Fig. 1. There are four depropanizers in the plant. The feed to the depropanizers is natu-ral gas liquid (NGL) that contains propane, iso-butane, n-butane and condensate or light naphtha. High-purity propane (~97%) is the overhead product of these depropanizers. Three depropanizers have air-fin coolers and one has a water cooler in the overhead con-denser service. The overhead pressure in the columns is controlled by withdrawing the propane product from the overhead. In other words, it is a flooded condenser pressure control where the level in the condenser is varied indirectly to control the pressure. In addition, the columns are equipped with variable pressure-control logic to take advantage of varying ambient temperature during the day. The variable pressure control increases the pressure in the morning and reduces it in the evening with varying ambient temperature. The control logic maintains a minimum subcool-ing to avoid vapor formation in the reflux drum and for proper functioning of the pressure control system. However, when the ambient temperature increases fast, the control system might fail

PIC

PI

PIC

PIC

150 to 250 psig

Air cooler

Depropanizer

Refluxdrum

Reflux pump

Boosterpump

PCVTo flare

Filtercoalescers

Propane drier

Propanetreaters

Storagebullets8 nos.

Changing leveland temperature

leading to changingpressures

To flare

Set pressure320 psig


135 to 200 psig

To flare



150 to 250 psig

Air cooler

Depropanizer

Refluxdrum

Reflux pump

Boosterpump

PCV

150 to 250 psig

Air cooler

Depropanizer

Refluxdrum

Reflux pump

Boosterpump

PCV

Propane rundown system. FIG. 1



to maintain the subcooling required and operator action would be necessary to reduce the feed to the columns.

During a capacity-expansion project, booster pumps were added to increase the propane production rate. Downstream of the pumps, there are filter coalescers to remove water carried over from the reflux drum. These are followed by driers and treaters that remove water and H2S from propane, respectively. The driers and treaters are molecular sieve beds that are taken through vari-ous cycles of operation such as absorption, draining, depressuring, regeneration, cooling and liquid filling. The switch between the various cycles is automated and air-operated isolation valves are used for this purpose.

The propane rundown is finally routed to storage bullets. The bullets are intermediate storage tanks where propane is routed to underground caverns for long-term storage, then to loading trucks and rail wagons. The bullets also act as intermediate stor-age for propane that comes from the underground caverns for loading trucks and rail wagons.

Problem. Relief valves are located on the filter coalescers and on the line, set at 320 psig. During summer, while the storage bullets and the columns are operated at higher pressures, these relief valves were chattering, causing damage to the valve seats. The relief valves located on treaters and driers that have a similar set pressure did not have any incidents of chattering or valve damage. The maxi-mum pressure recorded by the pressure indicator in the control room was only around 250 psig. Tell-tale gauges (local gauges that record maximum pressure) installed close the relief valves also recorded only a maximum of 250 psig. Even after repeated repairs and calibration of the relief valves, the problem persisted.

Actions taken. Drier/treater controls and relief valves.• Drier/treater controls. Switching the driers and treaters

between different cycles of operation is done using automated valves. It was suspected that the premature closing of the valves and/

or errors in logic might be causing flow restrictions. The switching logic was reviewed and revised to avoid any potential problems. Also, the closing of the automatic valves were checked by operators to ensure that they were not getting stuck or prematurely closing.

• Relief valves. Relief valves were replaced by pilot-operated valves with the following objectives:

• Relieving close to the set pressure• The effect of inlet line pressure drop was eliminated by tak-

ing pressure signals close to vessels and the main line.• Slower closure of the valves in the event of relieving.The steps taken described previously did not make much

improvement in the situation. Hence, it was decided to conduct a theoretical investigation of other causes of overpressure.

Theoretical investigation. The storage bullets act as inter-mediate storage where levels and temperatures can fluctuate. Therefore, a pressure transmitter was installed on the bullets to monitor the pressure continuously. The rundown system was modeled using simulation software. With monitoring the bullet pressure, it became evident that the propane in the bul-let was not always at equilibrium, and, due to level changes, considerable transient pressure changes were occurring. Some of the lowest pressures recorded in the bullets were used in the simulation for checking two-phase conditions. From the model, the following conclusions were reached:

• While the pressure in the bullets was lower than the vapor pressure, considerable vaporization was occurring in the rundown system (~15%)

• Some parts of the rundown lines were in the slug flow regime.• Due to a reduction in elevation, the vapor was partly col-

lapsing at a few locations.From these conclusions, it was surmised that the collapsing

of the vapor due to elevation changes might be causing transient shock waves. A phenomenon similar to condensation-induced water hammer in steam systems was suspected to be occurring due

to different causes.Unfortunately, most of the dynamic sim-

ulation programs are not capable of simulat-ing this type of transient pressure waves. Hence, only a qualitative analysis from the steady-state simulation results was made.

Solution. A backpressure controller was installed close to the storage bullets to iso-late the rundown system from the pressure variations in the bullet (Fig.2). Backpressure higher than the expected vapor pressure was maintained and this eliminated the relief valve chattering problem.

Case 2: Propane overhead system. The system in this case is the overheads of the depropanizers, previously described. The overhead system is shown in Fig 3. There are relief valves on the column overhead and the reflux drums with set pressure of 280 psig.

Problem description. Of the four relief valves on reflux drums, one used to chatter and cause frequent damage and another one received occasional damage. Both of these

PIC

PI

PIC

PIC

PIC

150 to 250 psig

Air cooler

Depropanizer

Refluxdrum

Reflux pump

Boosterpump

PCVTo flare

Filtercoalescers

Propane drier

Propanetreaters

Storagebullets8 nos.

Modificationimplemented

Changing leveland temperature

leading to changingpressures

To flare



135 to 200 psig

To flare


150 to 250 psig

Air cooler

Depropanizer

Refluxdrum

Reflux pump

Boosterpump

PCV

150 to 250 psig

Air cooler

Depropanizer

Refluxdrum

Reflux pump

Boosterpump

PCV


Modified propane rundown system. FIG. 2

EVENT

PCIprocesscontrol &instrumentationconference

Hosts:

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Hydrocarbon Processing and World Oil will host the Process Control & Instrumentation Conference (PCI) for the oil and gas industry 9–10 March 2011 in Galveston, Texas.

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WEDNESDAY, 9 MARCH 2011 8:15–8:30 a.m. Opening Remarks John Royall, President & CEO, Gulf Publishing Company

8:30–9:30 a.m. Keynote Presentation – Environmental Control Regulations9:30–10:00 a.m. Coff ee Break10:00–11:30 a.m. (choose one)

11:30 a.m.–1:00 p.m. Lunch1:00–2:30 p.m. (choose one)

2:30–3:00 p.m. Coff ee Break3:00–4:30 p.m. (choose one)

4:30 p.m. Opening Night Reception

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Inferential control modeling practices in the HP industry – Y. Zak Friedman, PhD, Principal Consultant, Petrocontrol

Dual valve control for refi nery blending optimization – Yangdong Pan, ConocoPhillips

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Safe/reliable/continuous/online monitoring of HF alkylation catalyst –Tom Kinney, Invensys Operations Management

SAFETY/SAFETY-INSTRUMENTED SYSTEMSAdvantages and disadvantages of using valve partial or full stroke testing – Claudio Passarella, Technical Specialist – Instrumentation, Petrofac Engineering & Construction

Plant safety through process control – Mohamed Soliman, PE, Saudi Aramco

Burner management systems for potential failure modes – Stephen Russell, Director of Automation & Process Control, Valero Energy Corporation

FIELDBUS/WIRELESSWireless and networking systems – Neil Peterson, Sr. Manager, Wireless Marketing, Emerson Process Management (invited)

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CDU APC experience at Marathon St. Paul Refi nery – Mark Schuler, Engineer, Marathon Oil Corporation

PCI CONFERENCE AGENDA (subject to change)

Session 1 Session 2

Session 3 Session 4

Session 5 Session 6

THURSDAY, 10 MARCH 2011 8:30–8:45 a.m. Welcoming Remarks Bill Wageneck, Publisher, Hydrocarbon Processing

8:45–9:30 a.m. Keynote Presentation – 2011 Economic Outlook for the Energy Industry9:30–10:00 a.m. Coff ee Break10:00–11:30 p.m. (choose one)

11:30 a.m.–1:00 p.m. Lunch – Keynote Presentation – What to expect in the PCI Industry1:00–2:30 p.m. (choose one)

2:30–3:00 p.m. Coff ee Break3:00–4:00 p.m.

4:00–4:45 p.m. Roundtable Discussion – The Future of the PCI Industry – PCI Conference Advisory Board (subject to change)

ASSET MANAGEMENTRFS-2: Measuring and controlling an 800-lb gorilla – Patrick Truesdale, PE, Senior Solution Consultant, Emerson Process Management – Micro Motion Division

A six sigma approach to save more petrodollars – Kurt Ausec, Fluor Corporation

Asset Management: The key to tracking and auditing refi nery instrumentation – Yokogawa (invited)

ADVANCED PROCESS CONTROL & ADVANCED REGULATORY CONTROL/ PROCESS CONTROLLosing the pyramid (and fi nding process control success) – Allan G. Kern, PE

MPC: What works and where are we going – Dr. Mark Darby, PE, CMiD Solutions

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MEASUREMENT INSTRUMENTATIONMethods and work practices that help prioritize the diagnostic information and develop reports that collate the data into bite-size chunks for daily analysis – Shell Deer Park Refi ning Company (invited)

Breakthrough multiphase measurement for wet gas – Richard Casimiro, Director, Business Development, Invensys Operations Management

Visual engineering – AVEVA (invited)

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Online decision support systems for optimizing plant operations – William Poe, Invensys Operations Management

How to operate the HPI—Risky tradeoff profi t meters – Pierre R. Latour, President, CLIFFTENT Inc.


SECURITYAutomation control systems security (A practical look at securing legacy and new automation control systems) – Marc A. Talamantez, Mustang Engineering

Session 7 Session 8

Session 9 Session 10

Session 11

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2011 PCI ADVISORY BOARDTom Shephard, Project Manager Automation and Controls Group, Mustang Engineering

Allan Kern, PE

Doug White, President of Advanced Control, Emerson Process Management

John F. Oyen, Manager Business Development Oil, Gas, Petrochemicals, ABB, Inc.

Daniel Duncan, VP & General Manager, Oil & Gas Division, Siemens Energy

Pierre Latour, President, CLIFFTENT Inc.

Alexandre Rodrigues, Controls Engineer, Petrobras

Stephen Russell, Director of Automation and Process Control, Valero Energy Corporation

Charles Mohrmann, Product Marketing and Strategy Director, Invensys Operations Management

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depropanizers have air coolers in the overhead condenser service. One of the propanizers with air coolers and one with a water cooler did not have this problem.

Analysis. The operating conditions of all the depropanizers were very similar and we could not identify any deviation of consequence regarding operating conditions. From analyzing his-torical data the following two interesting observations were made:

• Originally, the columns had a hot vapor bypass control for overhead pressure and later the control system was changed to a flooded control system. The relief-valve problems started subse-quent to the control system change.

• Most of the relieving incidents were reported to occur in the night. Due to variable pressure controls, the columns are operated at lower pressures during the night (180 to 200 psig) against a maximum of 250 psig during the day.

The fact that the relieving incidents occurred during the night, when operating pressures are lower, indicated that the problem was not linked to any rapid fluctuations in operating pressures. Hence, it was decided to look at any difference in installation between these columns. The piping drawings were reviewed and field measurements were made to determine the relative eleva-tion of the relief valves with respect to the bottom flange of the air-fin coolers. The relief valves that used to chatter had a relative elevation of +20 in. and +46 in. above the outlet flange of the air coolers. The relief valve on the system with the water cooler had a relative elevation of +87 in. The system that did not have any chattering problem had a relative elevation of only +1 in. Fig. 4 is a depiction of relative height.

Although the control systems were very similar, the pressure in the column with the water cooler never had drastic changes in the overhead pressure due to the reasonably steady water temperature. When the water temperature varied, the variation in pressure was slow and the control system did not make drastic changes. The varia-tions in air temperatures were more drastic and the pressures reached the maximum-allowed pressure of 250 psig in a span of a few hours. Also, in the night, the pressure was reduced up to 180 psig.

During the day, when the ambient temperature is high, the control system will tend to push the liquid level in the condenser down. In the cases where the relief valves are placed above the bottom of the condenser, this will lead to the draining of liquid and developing vapor space in the inlet pipe. In the night, while the ambient temperature reduces the vapor-inlet line might be collapsing and the higher liquid level in the condensers will force the liquid to rush into the transient low-pressure zone, causing chattering of the relief valves.

Solution. The preferred solution was to reduce the elevation of the relief valves. However, this could not be done since the flare header was located at a marginally lower elevation with respect to the relief valves. Reducing the relief-valve elevation would have led to pockets in the relief valve outlet line. It was verified that the relief valve on the column had enough capacity to cater to both the column and the reflux-drum relieving cases. Hence, it was decided to remove the relief valve on the reflux drum and to isolate it close to the vessel. This way, the possibility of forming vapor space that may lead to pressure transients was eliminated. All the block valves between the reflux drum and the relief valves were locked open to provide a clear relieving path. This modifica-tion was implemented only in the depropanizer that use to have frequent failure. HP

LITERATURE CITED 1 Kirsner, W., “Steam condensation-induced water hammer,” HPAC, January 1998.

PIC

PIC

PIC

PIC





Set pr280 psig

Set pr280 psig

Air cooler

DepropanizerReflux drum

Reflux drum

Reflux drum

Reflux pump

Boosterpump

PCV

Rundown

Air cooler

Depropanizer Reflux pump

Boosterpump

PCV

Air cooler

Depropanizer Reflux pump

Boosterpump

PCV

Set pr280 psig

Water cooler

Depropanizer

Reflux drum

Reflux pump

Boosterpump

PCV

Depropanizer overhead system. FIG. 3

George Mani is a process engineering specialist with BP Canada Energy Co. Currently, his responsibility is giving process engineering support to multiple natural gas processing and NGL facilities in operating and implementing projects. Mr. Mani has 30 years of wide-ranging experience in the oil and gas idustry.

Relativeheight

Reflux drum

Aircooler

Relative location of relief valve. FIG. 4

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When is CO2 more hazardous than H2SData shows potential harmful effects to workers due to acid gas exposure

K. TYNDALL, Pastor, Behling & Wheeler LLC, Round Rock, Texas; and K. McINTUSH, J. LUNDEEN, K. FISHER and C. BEITLER, Trimeric Corp., Buda, Texas

M any different types of facilities produce or use streams containing a high carbon dioxide (CO2) content (98+%) with low hydrogen sulfide (H2S) concentra-

tions, e.g., a few parts per million by volume (ppmv) to a few volume percent (vol%). Examples include CO2-flood enhanced oil recovery, pre-combustion carbon capture (from fossil fuel-fired power plants and industrial facilities) and sequestration, natural gas conditioning, and agricultural manufacturing, among others. In all of these industries, the potential for a release in a processing step or during transmission through a pipeline exists.

The health effects and dangers of H2S are well known, but those of CO2 are not as commonly understood. It is uncertain if industry realizes that CO2 is a mildly toxic gas and not just a simple asphyxiant like nitrogen. Because CO2 itself is toxic at higher concentrations, the high-purity CO2 streams can actu-ally be more hazardous than the H2S and they are the subject of discussion in this article. In such cases, the presence of H2S may actually allow easier detection of the CO2 danger.

This article reviews the hazards of H2S and CO2 and compares the effects from these acid gases on humans. Concentration levels corresponding to the immediately dangerous to life and health (IDLH) levels of the two gases are used to illustrate conditions where both H2S and CO2 are present, and the CO2 (not the H2S) is the predominant concern. A goal is to educate readers to think of CO2 as a mildly toxic gas and not just an asphyxiant, and to recognize conditions where it can represent the more significant hazard, even if small concentrations of H2S are also present.

Toxicity of H2S. Hydrogen sulfide is an intensely hazardous, toxic compound.1 It is a colorless, flammable gas that can be iden-tified in relatively low concentrations by a characteristic rotten egg odor. This acid gas is naturally occurring and is in the gases from volcanoes, sulfur springs, undersea vents, swamps and stagnant bodies of water and in crude petroleum and natural gas. Hydrogen sulfide is produced when bacteria break down sulfur-containing proteins, and it is a component of decomposing materials. In addition, H2S is also produced from man-made operations and processes such as petroleum refineries, food processing plants, tanneries, municipal sewers, sewage treatment plants, landfills, swine containment and manure-handling operations, and pulp and paper mills.

Hydrogen sulfide has a very low odor threshold, with its smell being easily detected by most people in the range of 0.0005

ppmv to 0.3 ppmv.2 As the gas becomes more concentrated, the odor increases with a strong rotten egg smell identifiable up to 30 ppmv. From about 30 ppmv to 100 ppmv, the gas is stated to have a sickeningly sweet odor. However, at concentrations above 100 ppmv, a person’s ability to detect the gas decreases due to a rapid temporary paralysis of the olfactory nerves in the nose that leads to a loss of the sense of smell. This means that the gas can be present in the environment at extremely high concentrations with no noticeable odor. This unusual property of H2S makes it very dangerous to depend solely on the sense of smell as a warning sign of the gas.3

Once H2S is released as a gas, it remains in the atmosphere for an average of 18 hours, after which it changes to sulfur dioxide and sulfuric acid.2 It is water-soluble and, therefore, it may partition to surface water or adsorb onto moist soil, plant foliage, or other organic material where it loses much of its toxic properties.

Hydrogen sulfide is classified as a chemical asphyxiant, similar to carbon monoxide (CO) and cyanide gases. It interferes with

TABLE 1. Symptoms from low to high concentrations of H2S

Exposure level Concentration, ppmv Symptom

Low 0–10 Irritation of the eyes, nose, and throat

Moderate 50–200 Coughing Hoarseness Shortness of breath Pneumonia Loss of smell ( > 100 ppmv)

High 200–500 Changes in respiratory tissue (200–400 ppmv per laboratory animals) Rapid respiratory distress and failure (acute exposure at > 500 ppmv for 1 to 4 hours)2

Very high > 2,000 Coma and death after single breath4

Known as “knockdown effect” with immediate immobilization and unconsciousness, possibly from disruption of oxidative metabolism in the brain



nerve cell function, putting certain nerves to sleep, including olfactory (as discussed previously) and the ones necessary for breathing. Table 1 shows the typical exposure symptoms of H2S.

It is important to note that while most chemicals are toxic, exposure has to occur (at a level that is considered toxic) before adverse health effects are observed. Most, if not all, of the irre-versible health outcomes including death have occurred due to overexposure to H2S in confined areas.

Toxicity of CO2. Carbon dioxide is a slightly toxic, odorless and colorless gas. It is typically found in air at around 360 ppmv (0.036 vol%) while exhaled air may contain as much as 40,000 ppmv (4 vol%). Table 2 shows the general affects of CO2 over different ranges of exposure.

At lower concentrations, CO2 affects the respiratory system and central nervous system. Too much CO2 also acts as a simple asphyxiant by reducing the amount of oxygen available for res-piration.6 At higher concentrations, too, the ability to eliminate CO2 decreases and it can accumulate in the body. In this way, CO2 differs from some other asphyxiants, such as nitrogen (N2). Unlike CO2, N2 does not get distributed throughout the body to cause an adverse health effect; rather, N2 acts simply by displac-ing oxygen from the air and, thereby, decreasing the amount of oxygen available for respiration. Result: CO2 is dangerous at a much lower level than some other asphyxiants, such as N2.

Nitrogen is discussed here because it is a common potential asphyxiant in industrial settings. The following example illus-trates the differences between CO2 and N2. Consider a hypo-thetical example where 90 parts of atmospheric air (normally 21% O2 and 79% N2) are mixed with 10 parts of either pure CO2 or N2. The resulting mixture compositions are shown in Fig. 1.

As shown in Fig. 1, the resulting mixture with CO2 addition contains 18.9% O2, 71.1% N2, and 10% CO2. As discussed pre-viously, such a mixture could potentially kill a person. Conversely, the mixture with N2 contains 18.9% O2 and 81.1% N2; while this mixture is lower in oxygen than normal air and below the recom-mended O2 % for workers, it is not likely to cause irreversible health effects. The effect of going from a 21% oxygen atmosphere to an 18.9% oxygen atmosphere is similar to going from sea level to about 3,000 ft in elevation (roughly the elevation of Midland,

Texas), as far as the oxygen partial pressure is concerned. Most people who are acclimated to sea level would have no trouble going to 3,000 ft in elevation.

In summary, mixing 10 parts CO2 with 90 parts air can pos-sibly cause a person breathing the mixture to die if exposed long enough. In contrast, mixing 10% N2 with air probably has little effect on a person. Clearly, it is very important to recognize that CO2 is not the same simple asphyxiant as N2.

Occupational exposure limits for H2S and CO2. Table 3 provides a summary of occupational exposure limits for H2S and CO2. Occupational exposure limits are typically designed to protect health and to provide for the safety of employees for up to a 40-hour work week, over a working lifetime. The threshold limit value (TLV) was developed by the American Conference of Governmental Industrial Hygienists (ACGIH) while the permissible exposure limit (PEL) is an enforceable standard developed by the Occupational Safety and Health Administration (OSHA). The short-term exposure limit (STEL) was developed by ACGIH and represents a 15-minute time-weighted average exposure that should not be exceeded at any time during the workday. The IDLH value was developed by the National Institute for Occupational Safety and Health (NIOSH) to provide a level at which a worker could escape without injury or irreversible health effects.

IDLH values are conservatively established by NIOSH to give a worker approximately 30 minutes to evacuate an area. The IDLH for both H2S and CO2 are purposefully established below levels at which adverse and irreversible health effects would be seen following 30 minutes of exposure. The IDLH for H2S was developed based on human data (and supplemented with information from laboratory animals) that showed that between 170 ppmv and 300 ppmv, a person can be exposed for one hour without serious health effects and that 400 ppmv to 700 ppmv can be dangerous if exposure is greater than 30 minutes. A person can be exposed to H2S at 800 ppmv for approximately 5 minutes before unconsciousness occurs, while exposure at 1,000 ppmv or greater can cause immediate respiratory arrest, unconsciousness and possibly death.

For CO2, a person can sustain exposure to the IDLH of 40,000 ppmv for 30 minutes with minimal signs of intoxication (e.g., changes in breathing rate, headache and fatigue). At 30 minutes of exposure to 50,000 ppmv CO2, signs of intoxication become more pronounced. A person can sustain exposure to 70,000 ppmv to 100,000 ppmv CO2 for about 5 minutes and signs of intoxication become intense with very labored breath-ing, visual impairment, headache, ringing in the ears and poten-tially impaired judgment. Air containing CO2 at a concentration

TABLE 3. Exposure limits for H2S and CO27

Compound TLV and PEL, ppmv STEL, ppmv IDLH, ppmv

H2S 10 15 100

CO2 5,000 30,000 40,000

TABLE 2. Symptoms from low to high concentrations of CO2

Exposure level Concentration, ppmv Symptom

Low 20,000 to 30,000 Shortness of breath, deep breathing

Medium 50,000 Breathing becomes heavy, 75,000 sweating, pulse quickens Headaches, dizziness, restlessness, breathlessness, increased heart rate and blood pressure, visual distortion

High 100,000 Impaired hearing, nausea, vomiting, loss of consciousness

Very high 300,000 Coma, convulsions, death5

18.910

CO2 addition

18.9

N2 addition

71.1 81.1

% O2

% N2

% O2

% N2

% CO2

Mixture compositions with 90 parts air and 10 parts CO2 or N2.

FIG. 1



greater than 100,000 ppmv (i.e., 10 vol%) can produce extreme discomfort and, as indicated above, can be life-threatening.

Table 4 shows an example of how a gas stream containing initial concentrations of H2S of 2,000 ppmv and of CO2 of 98 vol% would change assuming a uniform dispersion in air for both compounds. As shown in the table, when the IDLH of H2S (100 ppmv) is reached, the CO2 content is still above the IDLH level of 40,000 ppmv. Even more dramatic are the 5-minute exposure levels; when the H2S exposure level is at the 5-minute limit of 800 ppmv, the CO2 concentration is at 392,000 ppmv, which is far above the level a person can survive for 5 minutes. Thus, given the much higher percentage of the CO2 in this gas stream, the danger from CO2 is higher than the danger posed by H2S.

Potential exposure scenarios to H2S and CO2. In actuality, it is difficult to determine the likelihood of a release and the potential concentration a person may encounter following a release. A release could occur at any point in the processing unit or transfer pipeline depending on the source of the stream (see Fig. 2). Atmospheric conditions, such as the wind or physical location of the release (low lying area), can greatly affect the dispersion rate and exposure concentrations of the two compounds. Some potential exposure scenarios are discussed here.

If there is wind, a small release (i.e., not a catastrophic event) would most likely disperse relatively quickly. Under this scenario, a person downwind (unless they were within close proximity to the release) would probably not be exposed to a harmful concen-tration of either compound. In fact, the presence of H2S (which has an odor at very low concentrations) may actually provide an early indicator of a CO2 release that would otherwise go unde-tected. Although H2S may provide an early indicator of a release in certain situations, this should not be relied upon because H2S deadens the sense of smell at higher concentrations. Exposure should be kept to a minimum by applying sufficient engineering controls and safe work practices. Appropriate monitoring and personal protective equipment should always be used.

Because both compounds are heavier than air (the specific gravity for H2S and CO2 is 1.192 and 1.52, respectively), the most likely place to encounter harmful levels of either compound

would be in a low-lying area or depression. This is currently an issue for CO2 pipelines in which harmful levels of CO2 can accu-mulate in these areas, regardless of the presence of H2S. The pres-ence of H2S increases concerns due to its more insidious toxicity (i.e., it can render a person incapable of escape at sufficiently high concentrations). However, levels above the IDLH could occur in a confined space or depression for either compound. As indicated earlier, the presence of H2S may provide a warning that a release has occurred and prevent a person from entering the area where potentially dangerous levels of CO2 or H2S may be present. Note: The use of direct reading gas detection instrumentation and other protective measures should be required before entering confined spaces such as manholes, tanks, pits and vessels that could contain a buildup of these gases.

Potential synergistic effects of concurrent exposure. Since the mechanisms of action for CO2 and H2S are very dif-ferent, it is unlikely that exposure to both compounds will be worse than exposure to only one compound. Most occupational exposure limits are based on exposure to single compounds, even though it is recognized that multiple compounds may be encoun-tered, and Environmental Protection Agency only considers com-pounds additive if they affect the same target organ or act by the same mechanism. Moreover, industries such as swine production, where both CO2 and H2S are measured in the air, do not adjust occupational exposure limits for added worker safety nor have synergist effects (i.e., effects that are worse when in combination than when exposure is to a single compound) been noted for industries where exposure to both compounds occur.8

TABLE 4. Occupational limits example (high-purity CO2 gas with low H2S)

Dispersion CO2, ppmv H2S, ppmv Occupational exposure limit

Initial 980,000 2,000concentration, %

10 882,000 1,800

20 784,000 1,600

30 686,000 1,400

40 588,000 1,200

50 490,000 1,000

60 392,000 800 5-minute H2S exposure (800 ppmv)

70 294,000 600

80 196,000 400

90 98,000 200 5-minute CO2 exposure (100,000 to 70,000 ppmv)

95 49,000 100 H2S IDLH (100 ppmv)

95.9 40,000 82 CO2 IDLH (40,000 ppmv)

100 0 0

Example sources of high-purity CO2 and low H2S streams—CO2 dehydration unit.

FIG. 2A

Example sources of high-purity CO2 and low H2S streams—CO2 piping.

FIG. 2B



Evaluation of risk. Based on the general qualitative analysis of exposure to both H2S and CO2 discussed here, it appears that there is no increased risk from the presence of H2S at low levels (e.g., up to perhaps 2,000 ppmv or higher) in high-purity CO2 gas. In fact, in these types of gas streams, the potential exposure to high CO2 concentrations during a release event could be as dangerous, or more dangerous, than exposure to lower concen-trations of the more toxic H2S. At high concentrations, CO2 may accumulate in the body, which is different than some other asphyxiants (i.e., N2). It is most important to recognize the dif-ference between CO2 and other common asphyxiants. In some cases, the H2S in the gas may serve as a warning for the more hazardous CO2 environment. Dispersion modeling for specific release scenarios should be conducted to better understand pos-sible exposure limits and impacts on human health for both com-pounds. Appropriate safety precautions should be implemented including monitoring (both fixed and personal detection systems) and training on chemical hazards, personal protection equipment and safety rescue procedures. HP

LITERATURE CITED 1 US Environmental Protection Agency, Integrated Risk Information System (IRIS), Profile for Hydrogen Sulfide (CASRN 7783-06-4). Online database, http://www.epa.gov/iris/subst/0061.htm, August 2010. 2 “Hydrogen Sulfide Fact Sheet,” August 2004, SafetyDirectory.com; http:// www.safetydirectory.com/hazardous_substances/hydrogen_sulfide/fact_sheet. htm 3 Agency for Toxic Substances and Disease Registry (ATSDR), Draft Toxicological Profiles for Hydrogen Sulfide, US Department of Health and Human Services. Public Health Service, September 2004. 4 Gossel, T. A. and J. D. Bricker, Principles of Clinical Toxicology, Third Edition, Raven Press, New York, New York, 1994. 5 Goodman Gilman, A., L.S. Goodman, T.W. Rall and R. Murad, The Pharmacological Basis of Therapeutics, Seventh Edition, MacMillan Publishing Co., New York, New York, 1985. 6 Klaassen, C. D., Cassarett and Doull’s Toxicology—The Basic Science of Poisons, Seventh Edition, McGraw-Hill Publishing Co., New York, New York, 2008. 7 National Institute for Occupational Safety and Health, NIOSH Pocket Guide to Chemical Hazards, US Department of Health and Human Services. Public Health Service. Centers for Disease Control and Prevention. February 2004. 8 Lemay, S., L. Chenard and R. MacDonald, “Indoor Air Quality in Pig Buildings: Why Is It Important And How Is It Managed?,” London Swine Conference—Conquering the Challenges, April 11–12, 2004.

Carrie Beitler is a senior engineer at Trimeric Corp. in Buda, Texas. She has over 15 years of experience in process engineer-ing, process modeling and optimization of unit operations in the natural gas, petroleum refining and CO2 processing areas. She also specializes in the development of process design packages for the

fabrication of open-art technology such as caustic scrubbers, acid-gas injection units, glycol dehydrators and amine treaters. She graduated with a BS degree in chemical engineering from Purdue University.

Joe Lundeen is a principal engineer at Trimeric Corp. in Buda, Texas. He has 21 years of experience in process engineering, pro-cess troubleshooting, and facility installation for oil and gas produc-tion and CO2 processing clients. His recent experience has been focused on dehydration, contaminant removal, and transport of

super-critical CO2. He holds BS and MS degrees in chemical engineering from the University of Missouri, Rolla.

Ken McIntush, PE is a practicing chemical engineer and presi-dent of Trimeric Corp., a small company based in Buda, Texas, that is focused on chemical/process engineering. He has about 21 years of varied process engineering experience, serving clients in oil refining, oil and gas processing, silicon refining and several

other industries. Mr. McIntush performs troubleshooting, debottlenecking and other projects for the company. He holds a BS degree in chemical engineering from Texas A&M University, College Station.

Kirby Tyndall, PhD, DABT, is a senior consulting toxicologist with Pastor, Behling, & Wheeler, LLC. She is a board certified toxi-cologist with over 19 years of experience in the fields of toxicology, risk assessment and risk management. Dr. Tyndall has worked in both the environmental consulting and government sectors, and

has significant experience evaluating potential human health and ecological risks associated with exposure to contaminants in environmental media (air, water, soil, sediment and biota including fish, etc.).

Kevin Fisher, PE is a principal engineer at Trimeric Corp. in Buda, Texas. He has over 20 years of experience in process engineer-ing, research and development, and troubleshooting for oil and gas production and oil refining clients, as well as for private and government-sponsored research programs. He holds an MS degree

in chemical engineering from the University of Texas, and BS degrees in chemical engi-neering and chemistry from Texas A&M and Sam Houston State University, respectively.

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Use online analyzers for successful monitoring Improved analytics measure moisture and dew points for natural gas components

A. BENTON, Michell Instruments Ltd., Ely, Cambridgeshire, United Kingdom; and C. VALIZ, PDVSA, Jose Complex, Venezuela

Using advanced online water and hydrocarbon dew-point analysis techniques is critical to the efficient and reliable operation of natural gas liquid-extraction processes, pro-

ducing valuable light alkane liquids while the remaining gas is suitable for sales distribution. At its San Joaquin facility, Petróleos de Venezuela, S.A. (PDVSA) initially processed raw wellhead natural gas by separating residual hydrocarbon (HC) condensates, followed by glycol dehydration to reduce the water dew point. Reduced temperature separation was used to decrease the HC dew point prior to molecular sieve dehydration. This provided feed gas with moisture controlled to trace levels into the primary liquid-extraction process. Maintaining moisture concentrations to less than 0.1 parts per million (ppm) by volume is essential for reliably operating turbo expanders. The turboexpanders’ function is to use the depressurization of natural gas to achieve deep cooling of the process flow to –80°C. Avoiding ice formation within the separation process—particularly the turboexpander—is critically important for continuous plant operations and to prevent astro-nomical maintenance costs. Online measurement of dew point temperature within the feed gas, containing water precipitate and hydrocarbon condensate, enabled PDVSA process operators to extend the lifetime of the desiccant beds while protecting the turboexpanders from risk of damage.

The San Joaquin plant (Fig. 1) started operation in 1985 and currently provides a third of the total Venezuelan production of natural gas liquids, roughly 43,000 barrels per day, transferred

via pipeline to the PDVSA Jose Complex, near Barcelona. The Jose fractionation plant extracts butane, iso-butane and other individual alkanes. Residual gas production at 1,000 million standard cubic feet per day (MMf 3d) enters the Venezuelan mar-ket network.

The extraction process. The production train at the San Joaquin process plant is shown in Fig. 2, while Fig. 3 illustrates a schematic of an individual train.

Unprocessed wellhead natural gas (two-phase gas flow with entrained hydrocarbon liquids and water) enters the San Joaquin facility. It is initially processed using separation vessels to collect the bulk-entrained natural gas liquids that flow in the feed pipe-line. The gas at this point is highly corrosive and saturated with moisture, and is prone to hydrate formation. Hydrate formation is crystalline solids that form from condensed liquid water in combination with methane under pressurized conditions, even at temperatures above freezing. Initial dehydration is carried out at the earliest stage by a glycol contactor where liquid triethylene glycol (TEG) is spray injected as a desiccant into the gas flow ris-ing through a process column contactor (Fig. 4). Moisture-laden TEG is collected from the contactor for heat regeneration greater than 200°C, so boiling off the adsorbed moisture is done in a continuous circulation process.

At this stage, the gas is dry—the water dew-point temperature is lower than 0°C, below the process temperature conditions at

PDVSA San Joaquin extraction plant.FIG. 1 Production train at San Joaquin.FIG. 2



the prevailing process pressure. Therefore, while not entrained with liquid water, the gas is still heavily laden with HC liquids as a potential two-phase flow. The liquid content of the gas is suppressed through two stages of separation, before and after a Joule-Thomson (J-T) expansion valve that generates moderate

cooling of the gas by approximately 7 Kelvin through partial pressure reduction at 8 bars. This yields part of the natural gas liquid production while reducing the HC dew-point gas tempera-ture. The effect of this separation process is illustrated in Fig. 5. Reducing the HC dew point is important for the next stage of the process—dehydration to trace moisture concentration through molecular sieve columns (Fig. 6).

Reduction in the liquid loading of the gas is critical to the molecular sieves’ drying efficiency. If liquids are present, it adversely affects the moisture adsorption properties of the mate-rials’ lattice structure and the overall operation lifetime of the sieves. Reduction in the water dew point below –80°C (at process pressure equating to a moisture concentration of less than 0.1 ppmV) is critically important for operating the turboexpanders.

Turboexpanders, (Fig. 7) or expansion turbines, recover use-ful work from the expansion of a gas stream while lowering the process temperature, resulting in partial liquefaction of the bulk stream. As the expansion nears isentropic, the turboexpander reduces the process gas temperature significantly more than

Wellheadnatural gas

Natural gas liquids

Glycol (TEG)dehydrationcontactor

Glycolregeneration

system

Sepe

rato

rJ-

T in

let

Sepa

rato

rT-

E ou

tlet

Sepa

rato

rT-

E in

let

SeparatorJ-T outlet

Molecular sievecolumns x 4

1 2

2

34

1

Silicagel x 2 55 bar

-33ºC

17 bar-79ºC

Expa

nsio

n

Com

pres

sion

Turbo-expander

Residual gas tonational distribution

system 69 barg

DeethanizerLiquidstabilizer

Natural gas liquids

Joule-Thomson valve66 bar18ºC

58 bar11ºC

Process train schematic.FIG. 3

Glycol contactor tower.FIG. 4

40

60

80

100

120

140

Proc

ess

pres

sure

, bar

Hydrocarbon dew-point reduction at process stages

0-100 -80 -60 -40 -20 0 20 40 60 80

20

Hydrocarbon dew-point temperature, °C

Gas entering plantOutlet J-T seperatorResidual gas

Phase envelop (HC dew point curves) at stages throughout the liquid extraction process.

FIG. 5


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expansion across a J-T valve for the same 38-bar pressure drop. The consequences of higher moisture concentrations within the process gas can be catastrophic, as the lowest temperatures in the liquid extraction process approaches –79°C. If the gas water dew point rises above that temperature, then rapid ice formation will bring a high risk of physical damage to the rotating blades on the turboexpander. The deep cooled natural gas goes through multiple stages of liquid separation as the temperature cascades downward into a deethanization column. The result is a lean natural gas with only C1 and C2 hydrocarbons and some residual CO2 (Fig. 5). Compression of this remaining gas into the national distribution system is carried out by a centrifugal compressor linked to the shaft of the turboexpander, therefore capturing useful work from the gas expansion. A rich blend of propane, butane and heavier hydrocarbons forms the natural gas liquids transferred by pipeline to the fractionation plant.

Online dew-point analysis. Close monitoring of the dew-point levels at critical points across the San Joaquin extraction facility requires 12 combined hydrocarbon and water dew-point analyzers (Fig. 8). PDVSA installed two analyzers on the glycol dehydration contactors and five on each production train. Each train had four individual molecular sieve columns that needed to be monitored continuously along with the common header outlet feed to the turboexpander plant. Dew point is the temperature where a vapor or the combination of vapors condense to form a liquid, seen as dew drops, when the gas is cooled. When the dew-point temperature is below freezing, ice crystals form. HC

dew point is the condensation temperature of the heaviest HC components. Often, molecules with greater than 10 carbon atoms, present in ppm and sub-ppm concentrations, will condense to form HC condensates.

The analyzer (Fig. 7) will simultaneously measure HCs and water dew point using two discrete sensor cells applying dedi-cated sensor technologies (Fig. 9). A direct fundamental principle adapted from the optical cooled mirror technique is applied for the HC dew-point measurement. An abraded optical surface with a conical depression profile has been developed specifically for the detection of the low surface tension films that are characteristic of the precipitation that occurs at the HC dew point. A visible red spectrum source directed onto the abraded surface scatters the light. A photo detector is positioned so that it captures the scat-tered light. It diminishes rapidly as the condensate film forms on the surface, cooling down to the temperature region of the HC dew point by a heat pump under the automatic control of the analyzer firmware. As the condensate film forms, a ring of light develops as the surface within the conical depression becomes more reflective. However, it is the secondary effect of reduction in scattered light intensity that enables the analyzer to detect the HC dew point to a sensitivity of 5 mg/m3 condensate mass per volume of gas.

Unlike the HC dew point, an optical condensation technique cannot be applied to the water dew point measurement in this application. The water dew point temperature is significantly lower than the HC dew-point, such that any cooled surface would be flooded with condensate at a temperature far higher than the water dew point. For such measurements, a ceramic moisture sensor is used. Working on a moisture adsorption prin-ciple, the sensor adsorbs moisture into a micron-thin hygroscopic metal film in equilibrium with the flowing gas stream. The sensor exhibits an impedance change in proportion to the partial pres-sure of moisture vapor, the most elementary hygrometric unit. This is directly related to dew-point temperature, the measure-

Molecular sieve dehydration columns.FIG. 6

Turboexpander and a deethanizer column.FIG. 7

Hydrocarbon and water dew-point analyzer with a sampling system.

FIG. 8



ment unit where each sensor is calibrated. These sensors have an extremely wide sen-sitivity range, being calibrated traceable to national metrology standards from –100°C to +20°C dew point. They also have the capability to measure directly at process pressure conditions representing greater than 20,000 ppmV moisture content at full scale compared to less than 0.01 ppmV at the low end—this is important for measur-ing the turbo expander feed gas.

In-situ measurement verification. Although the sensors performing the online water dew point measurement are factory-calibrated traceable to national metrology standards, the critical nature of the water dew-point measurement for the turboexpander feed gas demands that PDVSA site personnel carry out periodic verification of the online analyzers during field operation. This is done in-situ using a portable dew point analyzer. Given the extremely low level of water dew point within the process (< –80°C dew point) and the process pressure of 60 barg, equating to less than 0.1 ppmV, it is advantageous to carry out the verification measurement by installing a reference dew-point sensor within the online analyzer on a temporary basis. This enables both online and reference sensors to be in total equilibrium with the process gas sample under the same conditions over the duration of some hours. Through this method, PDVSA was able to maintain the highest level of confidence in the measurements.

Process plant proving field trials. During June and July of 2009, PDVSA carried out trials to determine the operational status of the molecular sieve desiccant within the four drying col-umns on Train B at the San Joaquin facility. During normal plant operation, the columns were operated in an overlapping sequence for 36 hr before going offline for regeneration by heating to 300°C and back-flushing during an 8-hr period. At least three of the columns were in process operation in parallel at one time. During the plant-proving trials, the total adsorption capacity of each column was assessed through continuous operation until moisture breakthrough was detected by the online monitoring of dew point analyzers. After three years of use for the current molecular sieve material and an expected operational lifetime prediction of 3½ yrs, the purpose of the test was to determine the capacity of each bed and the urgency of scheduling when to replace each desiccant. Furthermore, the regeneration cycle times were reassessed to optimize the sequence throughout the remaining lifetime of the existing bed material. Fig. 10 illus-trates the moisture breakthrough on two individual desiccant beds occurring after 30 hr and 32 hr of continuous adsorption. The red trace shows the increase in the gas’ dew point in the common header resulting from these high moisture excursions. Given similar findings on the other two desiccant beds, PDVSA

reduced the operational adsorption period for each column to 27 hr, with a 9-hr regeneration sequence, to extend the useful life of the molecular sieve material through the intended replacement date of February 2010.

The proving trials served to reaffirm to the PDVSA plant operations and laboratory staff. It was shown that the perfor-mance of the analyzers after the first 18 months of success-fully monitoring the dew-point conditions was critical to the continuous process operation and the reliability of key plant equipment. HP

Permeable gold film

Hygroscopic mono-layer

Base electrode

Ceramic substrate

Moisture molecules

Schematic diagrams of ceramic impedance moisture (left) and HC dew-point detection technique (right).

FIG. 9

Traces from molecular sieve capacity tests. Note: the Y-axis is scaled in °F dew-point temperature.

FIG. 10

Carlos Valiz joined PDVSA Gas 15 years ago as senior chemist specializing in laboratory analysis. His current position is quality control supervisor for the complete Eastern Venezuela division of PDVSA Gas.

Andy Benton joined Michell Instruments Ltd in 1983, initially in the R&D section. Throughout his career he has specialized in devising innovative solutions to applications for online process gas and liquid analysis. Most particularly for the natural gas industry, Mr. Benton has advised best practice for water and hydrocarbon

dew-point control and measurement to producers, pipeline operators and large scale end users covering six continents.

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Advanced chemical process for treating sour gasTechnology avoids huge capital investments while speeding up results

C. A. ORTEGA PERALTA and M. J. ORTEGA CASTELÁN, NEUGA SA, Argentina

Current gas-sweetening technology requires plants to treat at least 1 million standard cubic meters per day (MMm3/d) of gas to be economically feasible. This article presents a versa-

tile technology that can be profitably applied to any gas flow from 10 thousand standard cubic meters per day (Mm3/d) up to several million with the benefit of reducing setup periods. This technology (Fig. 1) has been proven over five years in a gas-compression plant where sulfur and mercaptans (RSH) contamination unexpectedly rose from 150 ppm to 1,000 ppm. This allowed the company to comply with an existing commercial agreement for 100 Mm3/d.

The problem. In the proven installation, gas-flow production is collected along 50 km in an 8-in.-diameter pipeline. Gas-flow temperature is generally around 60°F, and pressure is as low as 3 kg/cm2. The contaminants to be scavenged are hydrogen sulfide (H2S), RSH and carbon dioxide (CO2). Plant process is completed by a set of alternative compressors, a distillation plant and dew-point adjustment for high pressure. Afterward, sweetened natural gas is dispatched through a transport pipeline injection (95%) and liquefied petroleum gas (LPG) to trucks (5%). The original sweetening processing plant was designed through seven towers containing a solid chemical scavenger-based in OxFey.

Over time, H2S and CO2 levels strongly rose, and mercaptans appeared as contaminants.

Scavenger products used were specific for H2S acid treatments, since contamination was prevalent in the beginning. However, the scenario changed to have lower yields, requiring using different liquid chemical injections downstream to obtain the required output specification. Operating costs increased to a point where the alternative to interrupt supply needed to be evaluated, despite the reputation impact in the market.

Due to this problem, it was proposed to test the chemical pro-cess, changing the “chemical scavenger,” in a pilot plant. Amine technology was quickly discarded since the gas standard flow being treated was heavy in contamination, implying an expensive instal-lation and high operative costs. As a consequence, testing began on a process using a strong alkali that reacts with weak acid con-taminants forming a buffer solution, which means the possibility of obtaining a controlled pH in the effluents. Moreover, it is possible to add commercial value to all the salts obtained in the reaction.

The design. Plant capacity defined what to consider in the selected process and included:

• Caustic recuperation and recycling• Byproducts concentration• Both, depending on the commercial alternatives.A specific study must include a gas-contaminant assessment to

define the technical application in function of the treatments to byproducts. In the opposite extreme, it is possible to simply install modular plants just near well-outs. An important advantage is the protection of pipeline transporting only sweet gas.

New process chemistry. Case with H2S (plus or without RSH), as contaminant:

H2S + H2O > SH– + (H3O)+ Ka = 4 x 10–7

RSH + Na+ > SHNa + R+

S HNa + (OH)– + (H3O)+ + H2O <=> SH– + 3 H2O + Na+

pH = 7.1 (buffer), pH control is required according to Hen-derson-Hasselbach to monitor log ((SH–)/(H2 S)).

Such control is related to the tower and packed design, drain and make-up of the scavenger, with continual checking of pH values. The solubility of H2S in water is important in industrial practice, especially in these environmental-awareness times. The fate of such an unfriendly component such as H2S is important to track. H2S is highly toxic, has a noxious odor and can form harmful-reaction products [such as sulfur dioxide (SOx)].

The treatment for the solubility in strong bases is the same as that in acids, but the effect is dramatically different. As with

Byproductschemical

treatmentsand recycling

Byproductsalkaline salts

Strong alkyl solution

Sweet gas

Sour gasH2S, CO2, RSHcontaminants

The technology and conceptual design. FIG. 1



the case of strong acids, the amount of the molecular species is dictated by the partial pressure. However, in this case, the reac-tions are shifted to the right producing more of the ionic sulfide species, thus dramatically increasing the total H2S concentration.

Case with CO2, as the contaminant.CO2 + H2O > H2CO3H2CO3 + H2O <=> H– CO3+ (H3O)+ Ka = 6 x 10–7

NaCO3H + H2O <=> H2CO3 + Na+ + (OH)– buffer pH = 9/10

Na2CO3 + 2 H2O <=> H2CO3 + 2Na+ + 2 (OH)– buffer pH = 11/13CO2 is a gas easily soluble in water and the solubility equi-

librium is maintained in agreement with Raoult Law. Part of dissolved CO2 is converted to carbonic acid, which reacts as weak acid forming buffer salts. Both salts obtained have important industrial uses. On the other hand, the sodium carbonate can react, giving back the caustic alkali in agreement with the fol-lowing:

Na2CO3 + CaO > CaCO3 + NaOH

Case with H2S and CO2, as the contaminant. In cases where both contaminants are present, plant design must consider that an H2S acid in spite of having similar Ka as H3CO2, is more powerful as a reducer. Thus, H2S is the first priority as a reactive in the presence of a strong caustic like the scavenger.

When the designer defines basic engineering, spacial velocity of sour gas and scavenger flow are dependent on the quantities of acid to be neutralized. In the case presented in Table 1, the tower design has the capability of neutralizing, at first, 30% of the H2S being present. Afterward, it neutralizes up to 70% of H2S and 60% of the total CO2 present in the original sour gas. Designers can define the capability of the strong caustic, while waste solution pH will vary with the byproduct salts present in the overall solution. HP

TABLE 2. New scavenger advantages

Plant size Low mass transference coefficient and high solution reactivity, allows high spacial gas velocity and small tower diameter. Plant size could be defined modular, in the area of well production. Plant size could be defined integrally, allow catching full well production up stream of plant compression.

Tower type High contact areas require the use of “packed towers,” the “mass transfer rings” type, offering: Very low pressure loss Minimal maintenance High chemical resistance No water absorption Low investment cost Simple and easy charge of the package

Effluents of process The process has no gaseous effluents. Liquid effluents have important industrial uses as byproducts. CO3Na2, CO3HNa, SNa2 and SHNa, are key raw materials in various industries. This process can be classified as “No contaminants to the environment.”

Slug-trap

Sweet andsour gases

mixedWell

Well

Well

Sweet gas

8-in. Freshsolution

Packedtowers

Recyclingprocess

Byproducts

Concentrator

To c

lient

s

The solution. FIG. 2

Carlos Alberto Ortega Peralta is the executive presi-dent at NEUGA SA. He has over 42 years of experience in process design and plant processes. Mr. Ortega Peralta invented the Titular Process.

Maria Jose Ortega Castelán is a manager NEUGA SA and has 10 years of experience in project management. She received a degree in industrial engineering and an MBA. Ms. Ortega Castelán is CFA certified.

TABLE 1. Flow and variables controlled

Scavenger ScavengerFlow, m3/d Dp, kg/cm2 H2S, ppm SHR, ppm CO2, ppm Inerts, N2 + CO2 % Byproducts and pH recirculation, m3/hr makeup, m3/hr

100.000 0.1 700 in 400 in 4,500 in 2 in SHNa 2 0.25 < 2 out < 2 out 2,000 out 1.8 out SNa2 CO3Na2 10.5

PLANT SAFETY


Safe detection of small to large gas releasesLook at these advantages in using ultrasonic leak detectors

E. NARANJO and S. BALIGA, General Monitors, Lake Forest, California; G. A. NEETHLING, Gassonic, Ballerup, Denmark; and C. D. PLUMMER, Safety Consulting and Process Engineering Analysis, Stoke on Trent, United Kingdom

It is clear in the oil and gas industry that large combustible gas releases can have catastrophic consequences. To prevent this, fire and gas safety professionals select and analyze a diverse set of

representative release scenarios, considering such factors as duration, orientation and type of gas.1 Understanding the hazard potential is a vital step in selecting sensors that are most suited for gas detection.

Despite such efforts in the original safety assessment, the capacity of an instrument to detect significant leaks is often inferred from its performance with small ones. As such, the instrument’s behavior under probable release scenarios is not well understood and generally leads to poor equipment selec-tion. Similarly, oil and gas workers may place undue emphasis on selecting detection instruments that reduce personal injury but fail to consider the sensor’s capacity to mitigate the consequences of major incidents.2

Ultrasonic gas leak detectors, non-concentration-based detec-tors used to detect leaks from high-pressure systems, are found to be suitable for detecting gas releases with mass flow rates ranging from a fraction of a gram per second to over 0.1 kg/s. The detection range scales with a sound pressure level (SPL) produced by these leaks, from a well-known isentropic flow rela-tion that assumes choked flow at the leak source. Simulations with inert gases and a mathematical model suggest ultrasonic gas leak detectors can safeguard personnel and plant assets from significant leaks.

Introduction. Ultrasonic gas leak detection usage has increased for detecting combustible and toxic gases in the oil and gas indus-try. Rather than relying on the gas reaching the sensor element, ultrasonic gas leak detectors detect a leak through the ultrasound produced by the escaping gas. These sensors have been shown to perform well under harsh environments and their advantages for detecting leaks in open, ventilated areas are well known.3–6

One of the principal advantages of ultrasonic gas leak detec-tors is that leaks can be simulated, providing a method for system verification that is uncommon among other types of gas sensors. Using an inert gas as a proxy, a technician can produce leaks at a controlled leak rate or through an orifice of known size and shape. Simulation is particularly useful for determining adequate cover-age for minor leaks, when the hazard can be prevented from esca-lating into a more severe incident. Naturally, what constitutes a minor gas leak depends on the application. The Health and Safety

Executive (HSE) Offshore Safety Division, for example, defines such leaks as “a gas release of mass release rate of less than 0.1 kg/s and duration of less than 2 min.” 7,8 Such leaks, if ignited, would not be expected to cause significant escalation or multiple fatali-ties, but may result in injuries or a fatality in the leak’s vicinity.

A second but often overlooked advantage of ultrasonic gas leak detectors is that they lend themselves well for modeling large leaks. Performance in the event of significant or major leaks is difficult to simulate in the field. At rates of 0.1 kg/s or more, gas leaks cannot be sustained but for short bursts; otherwise, the inert gas is quickly consumed. In some instances, the pressure required to produce a large leak can lead the jetting material to become a liquid, rendering it more difficult to gain a full understanding of the potential for ultrasonic noise generation by such leaks.

Some simple calculations enable engineers to estimate the detection range or the amount of ultrasound produced by signifi-cant leaks if the SPL for minor leaks is known. Such calculations are useful for allocating detectors in open fields where the only hazards of interest are significant leaks.

This article looks at formulas that were developed for deter-mining detection coverage when the minimum leak to be detected is large (≥ 0.1 kg/s). The results suggest that the relation between SPLs at different mass flowrates is a good predictor of detector range for significant combustible gas releases, but that they over-estimate coverage when the jetting substance is a liquid and gas mixture. SPL values obtained from the logarithm of a direct field term produce values that are much greater than those measured in the laboratory, suggesting a dampening effect on sound by grass, trees and other structures surrounding the sound source during the experiment.

Sound pressure level. Ultrasonic gas leak detectors operate on the principle that the escape of gas from a high-pressure pipe-line or vessel produces ultrasound. This ultrasound is measured as SPL, which can be calculated from knowledge of the sound source’s power, Ws , the distance of the sensor to the leak, r, and the ambient room constant, S:9

SPL = 10 log

Ws

10 12+10 log

1

2 r 2+

4

S (1)

Applying the ideal gas equation, the sound source’s power can be expressed as:

.

PLANT SAFETY


Ws =

RTM

m (2)

where � is an efficiency constant (0 ≤ � ≤ 1), R is the gas constant, M is the molecular weight, T is the absolute temperature, and m is the mass flowrate. Substituting Eq. 2 in Eq. 1 results in:

SPL = 120 +10 log

RTmM

1

2 r 2+

4S

(3)

Eq. 3 is useful for calculating the SPL of a leak if the mass flowrate for said leak and the SPL and corresponding leak for a second leak are known. Consider a second equation using Eq. 3:

SPL2 = 120 +10 logRT2m2

M2

1

2 r22+

4S

(3a)

Assuming that the distance to the sound source is constant, and subtracting Eq. 3a from Eq. 3 yields the relation

SPL2 = SPL1 +10 log

M1T2

M2T1

m2

m1

(4)

which can be simplified to:

SPL2 = SPL1 +10 log

m2

m1

(5)

when the molecular weight and absolute gas temperature for both leaks remain unchanged. Similarly, Eq. 3 can be used to estimate detection coverage, assuming the mass flow rate is constant. In this instance, subtracting Eq. 3 gives:

SPL2 = SPL1 +10 logr1 r2( )

2S + 8 r1

2

S + 8 r12

(6)

Assuming that the direct field term in Eq. 3 at a given location in the room is much larger than the reverberant field term; that is, (10 log (1/2πr2) >> 10 log (4/S)), Eq. 6 becomes:

SPL2 SPL1 + 20 log

r1r2

(7)

Eq. 5 is a useful tool for calculating the detection radius of ultrasonic gas leak detectors, provided that the SPL for a given mass flowrate is known. In instances when a change in background noise is expected (for example, by the removal of machinery) Eq. 6 or 7 can provide a working estimate of the range (assuming the minimum mass flowrate to be detected remains the same).

Experimental procedure. To verify the usefulness of Eqs. 5 and 7 in estimating detection range, SPLs were measured for minor and significant leaks and compared to predicted values. SPL measurements were taken with an ultrasonic gas leak detector mounted on a tripod at approximately 3 m from the ground (Fig. 1). To simulate the gas leaks, a rubber hydraulic hose with a 2-cm inner diameter and 4 m length was used. Both ends of the hose were fitted with high-pressure locks. On one end, an oil-filled pressure gauge was attached. On the other end a ball valve and a nozzle were attached. The nozzles had circular openings with nominal diameters of 1, 2 and 4 mm, as shown in Fig. 2, and were manufactured to specifications. All gases tested were supplied in standard 44H-sized cylinders (service pressure = 3,500 psi) and used as found.

Experimental results. Per HSE’s definition, significant gas releases have the potential to cause an event severe enough to be considered a major “accident” or to be of a size leading to significant escalation within the immediate area or module.7, 8 Fig. 3 shows SPL measurements for significant methane leaks as a function of distance and an SPL curve derived from Eq. 5. The dashed curve in Fig. 3 is a second-order polynomial fit to the predicted values and is presented to guide the eye. The estimated values for SPL were extrapolated from leak rates of m = 0.01 kg/s. As illustrated in Fig. 3, the predicted values agree, with an average percent difference between measured and predicted values of 2%. Other matches between predicted and experimental results are obtained for inert gases like nitrogen (Fig. 4).

Substances that are liquid when pressurized in gas cylinders generate less ultrasonic noise than predicted by Eq. 3. Fig. 5 shows SPL curves for CO2 and ethylene, two gases that are liquids at room temperature under moderate pressure. For both gases, the model overestimates the sound pressure level by an average of 13% at 10 m or more from the sound source.

If the SPL at a particular distance from the sound source is known, one can approximate the detection radius provided that

Experimental setup for leak simulation.FIG. 1 Stainless-steel nozzles for high-pressure leaks.FIG. 2

.

.

PLANT SAFETY


the mass flow rate is kept constant. From Eq. 6, the sound pres-sure level decreases with distance as log (1/r). Fig. 6 illustrates the SPL readings of the ultrasonic gas leak detector for a methane leak of m = 0.01 kg/s and the corresponding estimate from Eq. 7. The initial SPL was taken as 96 dB at r = 2 m. As evident from the graph, SPL decreases with distance at a much faster rate than predicted by the direct field term alone. Accounting for the value of S could result in a better match to experimental data.

Conclusion. With ultrasonic gas leak detection, a relation between SPL and mass flowrate can be effectively used to estimate detection radii for significant leaks. A similar relation that relies

on the direct field term [10 log (1/2πr2)] as the dominant factor underestimates the rate of SPL decrease over distance, suggesting that surrounding structures may have a dampening effect on the ultrasound. This may have been particularly the case with the experiments reported in this article, as they were performed out-doors. By fitting the experimental curve in Fig. 4, we find SPL in such experiment decreases at almost twice the predicted rate [37 log (1/r)] vs. [20 log (1/r)].

One important limitation of these equations is that they apply only to gas releases. Gas-liquid mixtures, which may be produced as a result of high pressures, invariably attenuate SPL. As shown above, when CO2 was pressurized above its critical pressure at

400 5 10

Distance from source, m15 20 25

50

60

70

80

SPL,

dB

90

100

110

120

Extrapolated from 0.01 kg/s using Eq. 5Measured at 0.1 kg/s

Measured and predicted values for methane leaks at 0.1 kg/s. Measurement error = ± 3 dB.

FIG. 3

400 5 10


50

60

70

80

SPL,

dB

90

100

110

120

Extrapolated from 0.01 kg/s using Eq. 5Measured at 0.1 kg/s

Measured and predicted values for nitrogen gas leaks at 0.1 kg/s. Measurement error = ± 3 dB.

FIG. 4

.

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PLANT SAFETY


room temperature to achieve a mass flowrate of 0.1 kg/s, the predicted SPL curve was higher than the one produced from experimental readings.

Besides the practical value of the equations, the test results dem-onstrate that ultrasonic gas leak detectors are well suited for detect-ing significant leaks. During the experiments, the test instrument never produced a false positive nor failed to respond to a gas leak.

Further work is needed to understand the scope of applica-tion of ultrasonic gas leak detectors to significant or even major incidents. As next steps, we plan to further characterize sensor behavior for combustible gas releases with mass flowrates larger than 0.1 kg/s. This study would throw light on the response for catastrophic incidents, where a potential detonation could lead to structural damage to surrounding areas or multiple fatalities. A topic that also deserves further consideration is sensor response to mixed-phase gas releases. Although the HSE has produced an excellent report on the subject, little work has been carried out on the sound characteristics of high-pressure jets produced by petroleum-gas mixtures.10 Given the broad application to which ultrasonic gas leak detectors have been found suitable so far, these are areas of investigation well worth exploring. HP

ACKNOWLEDGEMENTSThe authors are indebted to Toke Eng, Mads Kornbech, and Martin Olesen

at Gassonic A/S on preparing the article. Special credit also goes to Kamyar Babaielivari for setting up the leak simulation equipment and for his assistance in conducting the experiments.

LITERATURE CITED 1 Health and Safety Executive, Fire and Explosion Strategy, Issue 1, Hazardous Installations Directorate, Offshore Division, 2004. 2 Leistad, G. H. and A. R. Bradley, “Is the focus too low on issues that have a potential to lead to a major incident?” Proceedings of the SPE Offshore Europe Conference and Exhibition, Aberdeen, UK, 2009. 3 Naranjo, E. and S. Baliga, “Expanding the use of ultrasonic gas leak detectors: A review of gas release characteristics for adequate detection, International Gases and Instrumentation, Vol. 3, pp. 24–29, 2009. 4 Naranjo, E. and G. Neethling, “Safety in Diversity: The advantages of technology diversification in gas monitoring safety,” Hydrocarbon Engineering, Vol. 13, pp. 102–108, 2008. 5 Naranjo, E., “Selection and use of ultrasonic gas leak detectors,” Proceedings of the 54th IIS 474 pp. 287–296, Pensacola, Beach, Florida, 2008. 6 Hazardous Installations Directorate Semi-Permanent Circular, Acoustic Leak Detection, SPC/TECH/OSD/05, 2007. 7 Health and Safety Executive Offshore Technology Report 2001/055, OSD hydrocarbon release reduction campaign: Report on the hydrocarbon release incident investigation project – 1/4/2000 to 3/31/2001, HSE Books, Colegate, England, 2001. http://www.hse.gov.uk/research/otohtm/2001/ index.htm. 8 HID Statistics Report HSR 2002 002, Offshore Hydrocarbon Releases Statistics and Analysis, 2002, 2003. http://www.hse.gov.uk/offshore/statistics/ hsr2002/index.htm. 9 Raichel, D. R., The Science and Applications of Acoustics, Second Edition, Springer, New York, 2006. 10 Royle, M., D. Willoughby, E. Brueck and J. Patel, Measurement of Acoustic Spectra from Liquid Leaks, Research Report RR568, HSE Books, Colegate, England, 2007.

Edward Naranjo is a product manager for General Monitors. He has been with GMI for six years and contributes to product innovation and new product development, including initiatives on wireless-enabled fire and gas sensing, gas imaging, and ultrasonic gas leak detection. Dr. Naranjo has over 12 years of product devel-

opment experience in the industrial instrumentation, healthcare and consumer pack-aged goods industries. He received a BS degree in chemical engineering from Caltech and a PhD in the same discipline from the University of California, Santa Barbara. He also earned an MBA from the University of Chicago. Dr. Naranjo is the chapters’ regional director, western region, of the Product Development and Management Association and a certified new product development professional.

Shankar Baliga is a manager for research and development at General Monitors in Lake Forest, California. He is responsible for the development of new optical, acoustic and chemical sensing technologies for gas and flame detection. Recent examples of Dr. Baliga’s research interests include flame detection with neural net-

works and open path gas detection for ppm levels. He is a senior member of ISA and IEEE and a voting member on the ISA 12.13 committee for combustible gas detection instruments. Dr. Baliga received a PhD in physics from Ohio State University.

Gregory A. Neethling is the technology manager for Gas-sonic A/S, a General Monitors company. Mr. Neethling has over 10 years experience in ultrasonic gas leak detection, with an electrical engineering background. He started his career at Innova Air Tech Instruments in Copenhagen, Denmark as a research and develop-

ment engineer. Mr. Neethling’s knowledge of industrial gas detection stems from the development and deployment of ultrasonic gas leak detection devices over the last decade. He has published several papers on fire and gas detection implementation with emphasis on ultrasonic instruments.

Chris D. Plummer is a retired process safety consultant with Safety Consulting and Process Engineering Analysis in Stoke on Trent, UK. He received an undergraduate degree in chemical engi-neering from the University College in London. Mr. Plummer’s experience spans over 30 years in health safety and environment

(HSE) management, especially the use of safety devices in the oil and gas industry. He was chief HSE engineer at W.S. Atkins and has held a variety of positions in industrial safety and operations. Mr. Plummer is a chartered engineer, certified safety profes-sional and fellow of the Institution of Chemical Engineers.

400 5 10


50

60

70

80

SPL,

dB

90

100

110

120

Carbon dioxide andEthylene, extrapolated from0.01 kg/s using Eq. 5Carbon dioxide andEthylene, measured at 0.1 kg/s

FIG. 5

400 5 10


50

60

70

80

SPL,

dB

90

100

110

120

Extrapolated from SPL at r = 2 musing Eq. 7Measured at 0.1 kg/s

Measured and predicted values for methane leaks at 0.01 kg/s. Measurement error = ± 3 dB.

FIG. 6

Measured and predicted values for carbon dioxide and ethylene leaks at 0.1 kg/s. Measurement error = ± 3 dB.

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PLANT SAFETY


It is no secret that many of the process technologies within the hydrocarbon processing industry (HPI) carry their own set of challenges and risks. Inherent in the HPI is the continual

concern for worker and operations protection in the event of an explosion and fire. The ongoing history of refining is replete with accounts of disasters arising from simple and complex causes. Pipe corrosion was determined to be the prime cause of a May 2009 explosion and fire at the ethylene unit of Sunoco’s Marcus Hook refinery, located in Delaware. Superheated feedstock leaked out of a rusty pipe and ignited. The result was a vapor-cloud explo-sion (VCE). Even though the refining industry has experienced advances in process and safety technologies, the risk of a blast event can still occur—thus underscoring the need for greater emphasis on worker safety and equipment protection.

The design, development and deployment of blast-resistant structures to protect workers, power and process controls has been ongoing within the HPI and chemical manufacturing. In more recent years, the demand for these types of buildings has created a new industry that can provide benefits physically and financially to the HPI and other chemical processing plants.

Background. Although blast-resistant shelters are being used at land-based chemical processing plants, their origins can be traced to applications for externally reinforced, steel intermodal shipping containers in offshore safety applications. Freight containers have been in plentiful supply since their inception, and their structural strength makes them natural candidates for personnel protection from low-level blasts. Converted containers are resistant to blast loads in the 1 psi to 2 psi range. However, much higher loads are experienced during refinery blast events; given the distance and other variables affecting the force of a VCE, stronger structures are necessary. This imperative led to the design and fabrication of the first, custom-designed blast-resistant modules (BRMs), and the industry has been evolving ever since.

The industry response to ensuring personnel and plant safety reached a high degree of intensity after March 23, 2005. On that day, a series of explosions ripped through BP’s Texas City, Texas, refinery during the restarting of process equipment at the refinery’s isomerization unit, killing 15 workers and injuring 180 others (Fig. 2). A tremendous loss of manpower and equipment damage resulted from the accident; the unit did not come back online for another two years.

Since this incident, demand has increased significantly for blast-resistant, steel-fabricated buildings to provide more protec-

tion at HPI facilities. Industry guidelines have been established to facilitate the design, construction and optimal location of BRMs for personnel protection, as well as blast-resistant electrical equipment centers (BRECs) to protect critical electrical process functions of the facilities (Fig. 1).

Addressing safety concerns at HPI and other hazardous manufacturing facilities began largely in the 1990s, resulting in publication of the Occupational Safety & Health Administra-tion’s (OSHA) Process Safety Management (PSM) standards. In response to the OSHA publication, a joint effort was initiated by the American Petroleum Institute (API) and the Chemical Manufacturers Association to establish a set of guidelines directly addressing OSHA’s concerns in the PSM standards. This response is contained in API Recommended Practice 752, Management of Hazards Associated with Location of Process Plant Buildings.

Government, industry and market response. Follow-ing the conclusions reached in the wake of events at Texas City, OSHA initiated a series of National Emphasis Program Audits at US refineries, during which OSHA inspectors began issuing cita-tions to companies for failure to adequately protect essential or critical equipment at their facilities. This has added momentum to an already growing movement on the part of HPI firms to provide strong, ductile, affordable protective shelters. Advances in

Considerations for blast-resistant electrical equipment centers Guidelines explore protecting critical systems from disaster

D. COLE and D. AUSTIN, Lectrus Corp., Chattanooga, Tennessee

Blast-resistant electrical equipment center loaded for shipment at off-site manufacturing plant.

FIG. 1

PLANT SAFETY

64

the design, testing and manufacture of such structures has served to further ensure market viability for them.

Protecting personnel vs. equipment. The primary func-tion of blast-resistant shelters has been to protect personnel at facilities where at risk for accidental explosions exists. At the same time, risk managers, engineers and company owners also realize that the risk of exposure to overpressure or blast wave extends to critical and essential power and control systems of their facilities as well. Outside of protecting personnel during a blast event, nothing is more critical than sustaining the proper function of

process-related automatic shutoff valves and other critical power equipment, as well as water pumps for fire protection.

Personnel protection. The manufacturing industry for BRMs offers a wide range of sizes and blast ratings, conforming to International Building Code (IBC) design and construction practices. BRMs are most often used as a substitute for unrated construction trailers but may be configured into multiple sec-tions. Multi-sectional systems may be large single-story buildings or stacked to create a multistory configuration. Examples include offices, cafeterias and even sleeping quarters.

Aftermath of the BP Texas City March 2005 blast.FIG. 2 Side view of a blast-resistant electrical equipment center.FIG. 3

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PLANT SAFETY


Protecting equipment. As mentioned earlier, the IBC defines essential facilities as those whose processes must remain in operation or return to operation with minimal interrup-tion during or after a catastrophic event. Essential equipment is defined as equipment used in the power and control sys-tems that must remain online during an event to maintain the minimum necessary process functionality at the site. Critical equipment is that which is used in those systems and must be returned to functional status in minimal time, with minimal cost and effort.

While massive attention and effort have been given to pro-vide blast-resistant shelters for personnel protection in areas with potential for overpressure at HPI facilities, a commensurate effort is being directed at protecting critical and essential power and control systems (Fig. 3). Concerning such processes and the asso-ciated critical equipment, OSHA’s PSM standard specifically lists equipment that the employer deems critical to process safety, “…because of its potential for significant impact on the safety of a process involving highly hazardous chemicals if it did not maintain its mechanical integrity.” The standard goes on to name equipment types including, but not limited to:

• Relief and vent systems and devices• Pumps• Emergency shutdown systems• Controls (including monitoring devices and sensors, alarms

and interlocks).The logical and most effective solution for protecting critical

processes and associated equipment is a BREC rated to handle pressures of the type experienced at Texas City in 2005.

Current building standards. Blast-resistant buildings are not currently defined by a governing industry standard. Therefore, engineering analyses and testing are used to certify individual components and system designs. This responsibility falls primarily

on the shoulders of engineers, designers and manufacturing firms that produce blast-resistant modules.

Since the purpose of BRMs is to protect people, they must meet architectural and life-safety codes. However, these require-ments do not extend to equipment centers.

Typically the size of an office trailer, a BRM may be installed in a multitude of varying configurations (including multilevel) and floor plans. The buildings may be similar in design and construction to their first-generation cousins, steel shipping containers, but modern BRMs are larger, considerably stronger and specially designed for placement in hazardous areas. Most of the standard features of ship-ping containers, i.e., all-welded steel construction, crimped plate walls, steel-tube framing and reinforced plate roofs, also apply to blast-resistant equipment shelters.

Modern BRMs are constructed with specially designed, heavy framed doors, windows and HVAC. Any external system or accessory must be designed and constructed to withstand the forces of the rated blast pressures. Most of these construction features are also attributable to BRECs. The BRM exterior will respond during an overpressure event by deflecting, whereby some structural components may per-manently deform. At the same time, the walls and roof are designed to remain intact, absorb the blast forces and protect the occupants.

Functional differences between BRMs and BRECs. Whereas BRMs have the option of being installed as either per-manent or temporary structures, BRECs are sited within refineries as permanent structures.

The most desirable location for an electrical equipment center at a refinery is as close to the processing operation and mainte-nance personnel as possible. The owner has far more flexibility in siting BRECs than is available for siting BRMs. Siting decisions are based upon economics when the incident risk is immediate, and the costs of additional cabling and other delays from increased standoff distances are high.

TABLE 1. Functional differences between personnel and equipment shelters

Design consideration Personnel Equipment

Protection People Equipment

Allowable response Walls and roof may deform but must not generate heavy Walls and roof may deform but must not impact equipment. Connections internal debris. Allowable deformations typically follow must have adequate protection to withstand relative movement. Some ASCE guidance equipment may also be shock sensitive, requiring flexible mountings.

Construction Seam welded crimp plate, wood framing and sheetrock All steel SWCP or interlocking panel. Typically no interior “finish out” is required

Access IBC/ADA OSHA

Foundation type Slab-on-grade Elevated

Doors Opened frequently Open infrequently for equipment check

TABLE 2. Design specifications for various BREC construction types

Construction type

Product design feature Type I Type II Type III

Description Medium-gage G90 steel; interlocking panels Heavy-gage G90 steel; interlocking panels Seal-welded crimped heavy steel plate

Panel width, mm 400 300 n/a

Panel connection type Interlocking Interlocking Continuously welded

Exterior wall/roof thickness, mm 75 100 100

Wall deflection space, mm 0–140 38–100 64–178

Total wall thickness, mm 75–270 100–280 100–355

PLANT SAFETY


Typical types I, II and III structure construction. Unlike commercial-grade, pre-engineered metal buildings, today’s BRECs use heavy structural members and either crimped plate or interlocking heavy-gauge wall panels. Base members consist of C-channels, wide-flange structural beams, and wall panels are sup-ported with tube steel. Up to 12 mm- (1/2-in.) thick metal plate is continuously welded to the base to form the floor. Floor cutouts are made for all electrical equipment located within the shelter. Wall and roof construction details depend upon the maximum blast loadings.

Table 1 shows the functional differences between blast-resistant modules used for personnel vs. equipment protection. Table 2 lists the design specifications for various BREC construction types.

It is also notable that the older, 14x40-foot size limitation for BRECs is no longer a factor, since any of the three unit types can be constructed with custom dimensions and loadings in mind. HP

BIBLIOGRAPHYChase, R., Associated Press, “Pipe corrosion led to Delaware refinery explosion,” Sept. 8, 2009.Cole, D., R. H. Bennett and D. Austin, “Protecting Essential Refining Operations Using Blast-Resistant Electrical Equipment Shelters,” IEEE- PCIC-AN-22, 2008.Design of Blast Resistant Buildings in Petrochemical Facilities, American Society of Civil Engineers, Task Committee on Blast Resistant Design, New York, New York, 1997.Fatal Accident Investigation Report: Isomerization Unit Explosion—Final Report, Texas City, Texas, incident date: March 23, 2005, report date: Dec. 9, 2005.Gehring, G. and P. Summers, “Constructing and designing blast-resistant buildings,” Hydrocarbon Processing, November 2005, pp. 55–61.International Building Code, Section 1602, Washington, DC, 2006.

Management of Hazards Associated with Location of Process Plant Portable Buildings, API RP 753, First Edition, American Petroleum Institute, Washington, DC, June 2007.Petroleum Refinery Process Safety Management National Emphasis Program, CPL 03-00-004, US Department of Labor, Occupational Safety and Health Standards, Washington, DC, 2007.Process Safety Management of Highly Hazardous Chemicals, 29 CFR 1910.119, US Department of Labor, Occupational Safety and Health Standards, Washington, DC, Subpart H, 1992.Samara, M., ASCE Abstract, Nonstructural Considerations in Design of Blast- Resistant Buildings, Vol. 3, Issue 4, November 1998, pp. 172–175.

David Cole is the vice president of corporate engineering for Lectrus Corp. His current responsibilities include product design, research and development, and code compliance for the com-pany’s complete line of custom, walk-in metal electrical equipment enclosures. Mr. Cole also represents Lectrus on various technical

and industry associations, including IEEE. He graduated from North Carolina State University with a BS degree in mechanical engineering in 1985, and from University of Phoenix with an MBA in 1995. He has had a diverse career in medical R&D, computer-peripheral manufacturing, and electrical control and enclosure design.

Deron Austin is the vice president of marketing for Lectrus Corp. Mr. Austin has over 20 years of experience in sales and marketing of engineered products and is a licensed professional engineer in the State of Tennessee. Prior to joining Lectrus in June 2008, he was employed by Propex, where he helped increase

the global demand for the company’s civil engineering products. As vice president of marketing for Lectrus, he is responsible for the company’s strategic marketing initiatives, marketing communications tactics lead development, branding and new market, channel, product and service commercialization efforts. He is a member of the Institute of Electrical and Electronics Engineers, and holds a BS degree in civil engineering from Bucknell University.

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Selecting the Best Solvent for Gas TreatingPROCESS INSIGHT

Selecting the best amine/solvent for gas treating is not a trivial task. There are a number of amines available to remove contaminants such as CO2, H2S and organic sulfur compounds from sour gas streams. The most commonly used amines are methanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA). Other amines include diglycolamine® (DGA), diisopropanolamine (DIPA), and triethanolamine (TEA). Mixtures of amines can also be used to customize or optimize the acid gas recovery. Temperature, pressure, sour gas composition, and purity requirements for the treated gas must all be considered when choosing the most appropriate amine for a given application.

Primary AminesThe primary amine MEA removes both CO2 and H2S from sour gas and is effective at low pressure. Depending on the conditions, MEA can remove H2S to less than 4 ppmv while removing CO2 to less than 100 ppmv. MEA systems generally require a reclaimer to remove degraded products from circulation. Typical solution strength ranges from 10 to 20 weight % with a maximum rich loading of 0.35 mole acid gas/mole MEA. DGA® is another primary amine that removes CO2, H2S, COS, and mercaptans. Typical solution strengths are 50-60 weight %, which result in lower circulation rates and less energy required for stripping as compared with MEA. DGA also requires reclaiming to remove the degradation products.

Secondary AminesThe secondary amine DEA removes both CO2 and H2S but generally requires higher pressure than MEA to meet overhead specifi cations. Because DEA is a weaker amine than MEA, it requires less energy for stripping. Typical solution strength ranges from 25 to 35 weight % with a maximum rich loading of 0.35 mole/mole. DIPA is a secondary amine that exhibits some selectivity for H2S although it is not as pronounced as for tertiary amines. DIPA also removes COS. Solutions are low in corrosion and require relatively low energy for regeneration. The most common applications for DIPA are in the ADIP® and SULFINOL® processes.

Tertiary Amines A tertiary amine such as MDEA is often used to selectively remove H2S, especially for cases with a high CO2 to H2S ratio in the sour gas. One benefi t of selective absorption of H2S is a Claus feed rich in H2S. MDEA can remove H2S to 4 ppm while maintaining 2% or less CO2 in the treated gas using relatively less energy for regeneration than that for DEA. Higher weight percent amine and less CO2 absorbed results in lower circulation rates as well. Typical solution strengths are 40-50 weight % with a maximum rich loading of 0.55 mole/mole. Because MDEA is not prone to degradation, corrosion is low and a reclaimer is unnecessary. Operating pressure can range from atmospheric, typical of tail gas treating units, to over 1,000 psia.

Mixed SolventsIn certain situations, the solvent can be “customized” to optimize the sweetening process. For example, adding a primary or secondary amine to MDEA can increase the rate of CO2 absorption without compromising the advantages of MDEA. Another less obvious application is adding MDEA to an existing DEA unit to increase the effective weight % amine to absorb more acid gas without increasing circulation rate or reboiler duty. Many plants utilize a mixture of amine with physical solvents. SULFINOL® is a licensed product from Shell Oil Products that combines an amine with a physical solvent. Advantages of this solvent are increased mercaptan pickup, lower regeneration energy, and selectivity to H2S.

Choosing the Best AlternativeGiven the wide variety of gas treating options, a process simulator that can accurately predict sweetening results is a necessity when attempting to determine the best option. ProMax® has been proven to accurately predict results for numerous process schemes. Additionally, ProMax can utilize a scenario tool to perform feasibility studies. The scenario tool may be used to systematically vary selected parameters in an effort to determine the optimum operating conditions and the appropriate solvent. These studies can determine rich loading, reboiler duty, acid gas content of the sweet gas, amine losses, required circulation rate, type of amine or physical solvent, weight percent of amine, and other parameters. ProMax can model virtually any fl ow process or confi guration including multiple columns, liquid hydrocarbon treating, and split fl ow processes. In addition, ProMax can accurately model caustic treating applications as well as physical solvent sweetening with solvents such as Coastal AGR®, methanol, and NMP. For more information about ProMax and its ability to determine the appropriate solvent for a given set of conditions, contact Bryan Research & Engineering.

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ENVIRONMENT


G lobally speaking, there is an exalted awareness of environmental degra-dation caused by industrial activi-

ties including the hydrocarbon processing industry (HPI). Scientists and environ-mental groups are linking industrial activ-ity as the potential source for greenhouse gas (GHG) emissions, stratospheric ozone depletion, acid rain and acidification, eutro-phication, soil degradation, technological hazards, chemical mists and fog. Some cli-mate experts and other scientists believe that these conditions may pose potential dam-age to human beings. Indeed, this potential effect is the topic of many discussions at both national and international forums.

Environmental considerations assume significant importance in chemical and pet-rochemical processing, which contribute effluents and emissions capable of degrading the environment. Accordingly, HPI opera-tors are challenged. They must solve how to increase manufacturing of high-demand goods and services, and to maintain the profitability of their parent organizations while effectively tackling consequential environmental issues to the environment and general public. Effective environmental management assumes paramount impor-tance in addressing the numerous issues over pollution and emissions control, while simultaneously maintaining safety and sustainability of the industry. Clean initia-tives in the HPI are a major development.

Challenges for industry. The growth of the HPI has been guided mostly by the necessity to increase production at lower costs, and it has contributed in some degree to degradation of water resources, soil and air around the processing plants. Worldwide, the focus of pollution control

has shifted from end-of-pipe treatment to source reduction, thus lowering emission generation and applying clean technol-ogy and sustainable development. It has become imperative that environmental considerations will play a substantive role in the future development of the HPI, espe-cially at a time when more industrial activi-ties are expanding in developing countries.

In recent years, several studies in differ-ent parts of the world focused on this issue. Key objectives of the studies are to identify issues in environmental protection within different industrial processes; to assess the extent that national and international guidelines regarding pollution control and environmental management can and are being implemented; to understand the problems encountered in environmental management; and to explore the reasons for noncompliance. Suggestions were also made on the basis of the listed studies to develop guidelines for environmental pol-icy and to adopt cleaner technologies that will foster industrial development with least degradation impact on the environment.

Environmental management. At present, most HPI processing units in developed or developing countries have specific environmental policies over site emissions, effluents and waste disposal; these operations are guided by rules and programs set by regulatory authorities. New plants under development include modern technologies that were part of the design inception stage; pollution preven-tion is a part of the design process and is not an afterthought for modern HPI facili-ties. Older process units are now operated with add-on state-of-the-art pollution-con-trol equipment and technologies.

Environmental control departments attached to the plants usually exhibit meticu-lous care to see that the company’s environ-mental goals and agendas are achieved. Thus, effective emission control facilities exist in most HPI facilities, and they are operated with due diligence. The stipulations of pol-lution-control and environmental protection agencies are also within the achievable limits of the available technology. Excursions, at times, still occur—often during abnormal operating events such as startup, shutdown or during accidental situations.

Several national and the international standards covering a wide range of param-eters have been developed to specify the emissions and effluents from the HPI. These include pH, ammoniacal nitrogen, nitrates, fluorides, phosphates, total suspended sol-ids (TSSs), oils and fats, and chemical and biological oxygen demands in the effluent streams, particulate matter, nitrogen oxides (NOx), sulfur oxides and carbon monox-ide (CO) in exhaust streams. Radioactivity, toxicity, presence of heavy metals, organics, biological pollutants, pathogens, etc., are also monitored in specific cases.

Clean technologies. Current devel-opments in environmental chemistry and chemical engineering have helped plant operators reduce effluent generation at the source and thus eliminate treatment and disposal of waste and byproducts. Very often, treatment from industrial opera-tions is linked to the processing technolo-gies adopted in the plants. Over the years, the specific consumption of raw material and energy for manufactured products has registered a continuously declining trend accomplished with the adoption of efficient technologies and best operating

What are the strategies for sustainable chemical production?New environmental challenges require a new way of thinking by the hydrocarbon processing industry

M. P. SUKUMARAN NAIR, Special Secretary to Government of Kerala, and Chairman, Chemical Engineering Division Board of the Institution of Engineers, India

ENVIRONMENT

70

practices at the plant level. This invariably contributes to achieving better environ-mental standards through reduced emis-sions, effluents and solid waste per ton of product manufactured.

Further improvements toward better environmental quality may require major design changes involving additional invest-ment or going for a newly proven and com-mercialized process. This is a costly option and efforts in this direction are limited unless they bring economic incentives

such as increased productivity, lower energy consumption, etc. In the case of products having high-water intensity, there is an eco-nomic benefit in reusing treated effluents to conserve water.

The startup and shutdown of plants are situations that can potentially increase emissions generation as compared to normal operations. Most plants are equipped with specific provisions to control such situations.

Most pollution-prevention methods implemented in the HPI follow prescrip-

tive approaches that adhere to standardized procedures built around questionnaires and checklists. The new approach is to adopt a more descriptive approach in which process operators are challenged to attack pollution problems and devise new and innovative ways for solving them.

New management approaches are under-taking substantial efforts to develop “green belts” and maintaining greenery around pro-cess plants to reduce the impact of GHGs. This is an important step in the direction of sustainable environmental control.

ISO programs for the environ-ment. Establishment of ISO 14000 Environment Management Systems and a corporate environmental agenda for regular monitoring and control is another major step in environmental protection. These systems are intended for continuous improvement of existing operations from the environmental angle. Certain indus-tries have adopted a zero-effluent approach incorporating total recycle and reuse of effluents back to process. Zero effluents still remains more of a concept than its effective implementation to a reasonable degree of reliability. European process plant operators use the best available techniques (BATs) in their plants for environmental control. Both effluent specific standards and product specific standards are available.

In India and in many other develop-ing countries, systems are applied for controlling and reducing pollution from plants with in the limits set by the statu-tory authorities, i.e., the Pollution Control Boards (PCB). Some operating units do not put in further efforts to reduce the pol-lution effects beyond the limits prescribed by the PCBs. This is primarily due to the lack of incentives to encourage additional investment toward improved technology aiding better environmental quality.

Most HPI operations emit large quan-tities of carbon dioxide (CO2), which is a major GHG to the atmosphere. There are no emission standards for CO2 as pre-scribed by the statutory bodies. Attempts to reduce GHG emissions globally to tackle climate change may bring in specific lim-its for CO2 emissions or calls for effective measures for sequestration in future.

Every processing unit imposes certain environmental burdens to the local envi-ronment, and its impact categories are acid-ity, global warming, human health effects, ozone depletion, photochemical smog, aquatic oxygen demand and eco-toxicity to aquatic life, etc. A parametric assess-

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ENVIRONMENT


ment of the contribution of each of these components can be used to compare yearly performances of plants.

The necessity of maintaining a safe work environment for employees and the neighboring community is well recognized. For this purpose, extensive hazard and risk analysis using techniques such as hazard operability (HAZOP) studies and quan-titative risk assessment (QRA) are con-ducted based on which safe systems, work practices and risk-reduction measure are now adopted. The environment manage-ment plans (EMPs) of the production units are capable of mitigating risk from most expected crisis situations barring those from nightmare incidents such as earth-quakes, sabotage, etc.

Public information. Information to the public regarding the environmental conse-quences of these plants is very important. The communities associated with these units have a right to know the environmen-tal risk that they are subjected to. In most countries, it is now mandatory that an envi-ronment impact assessment (EIA) be done prior to implementation of a project having large-scale environmental consequences. A proper EMP is also to be in place before the unit startup.

Environmental challenges. Cli-mate change across the world, depletion of ozone layer in the outer atmosphere, loss of biodiversity elements such as migratory species and important genetic resources; widespread degradation of land, urban air, forests and natural waters and marine ecosystems; and accumulation of persis-tent organic pollutants in nature are major global environmental concerns. These issues have an impact that transcendent national boundaries and require global solutions. We have over 200 international legislations governing environmental issues and together with currently available tech-nology and adopting best practices mitiga-tion for further degradation are possible.

India, for example, has adopted a national action plan for climate change and has framed a comprehensive auto fuel policy that consider among other things, availability and security of supplies, vehicle technology, cost-effective emission reduc-tion, fiscal measures and institutional means to bring about progressive improve-ments by reducing vehicular emissions on ambient air. The fuel cell as a power source is becoming a viable alternative to internal combustion engines with least environ-mental impacts. Thus, concerted efforts

are required both at the national and inter-national levels to stop further degradation and reverse trends.

Stress on environmental health. National environmental policies should foster efforts for sustaining environmental health of the public and to call for a discrete assessment of pollutants entering the natural environment from human interventions in terms of their toxicity, persistence, mobility, bioaccumulation and methods available for source reduction and control mechanisms.

Shift toward alternatives. More industries are switching over to environ-ment-friendly raw materials and energy resources to improve sustainability. Several examples are available:

• Use natural gas, predominantly methane (CH4), as a relatively benign raw material and energy source than other petro-leum feedstocks including naphtha, fuel oil and coal to produce ammonia, which is the basic building block of the nitrogenous fertilizer industry. Natural gas as feedstock would reduce pollution generation. This route would offer lower CO2 emissions, reduce waste generation and decrease energy intensity for the final product.

• Replace organic solvents with water. Replacing volatile organic compounds (VOCs) as reaction medium in organic synthesis is another important innova-tion. Using ethylene dichloride (EDC) for extraction of food items has been replaced by n-hexane.

• Manufacturing sulfuric acid from pyrite roasting has a lesser impact than using elemental sulfur. Recycling of met-als, recovery of metals from spent catalysts, sludge from metallurgical operations, etc., could reduce the impact of large-scale min-ing of metals and minerals.

• Begasse from sugar industry is used as a raw material for paper industry in place of wood pulp. Treated softwood, coir and bamboo composites are extensively used in place of hardwood for furniture. Several oxidation reactions involving air are being replaced with gaseous oxygen to mitigate toxic NOx generation. Application of next-generation polymers and plastics in place of metal in highly corrosive appli-cations, are intended to reduce the envi-ronmental burden arising out of products manufactured and lead to sustainability.

• Construction industry is being increasingly encouraged to use locally available materials to replace steel, glass, wood and cement.

• Replace fossil fuels with hydrogen in engines is in an advanced research stage. Once it becomes technically and economi-cally feasible, fuel cells can offer an environ-ment friendly option for transportation.

• Natural zeolites are finding exten-sive applications in place of alkyl ben-zene sulfonates (ABSs) as detergents.

• Power generation using vacuum res-idue from crude refining operations is a sustainable option to dispose of the unmar-ketable end products. These bottoms, after improved crude utilization processes such as hydrocracking, are highly viscous, heavy and difficult to handle and, as such, are not marketable. The quantity of residue from refineries varies from 20% to 40% of the throughput depending on the crude char-acteristics and secondary process applied. Refiners are seeking alternative residue uti-lization strategies to produce lighter high-value products and to increase competi-tive positions in a market where light-oil product(s) demand is steadily increasing.

• Biofuels are being used in the auto-motive industry. Ethanol and biodiesel have emerged as reasonable alternatives to the conventional petroleum fuels. These are based on agricultural feedstocks and they can be easily blended with hydrocarbon fuels unto 50% blends and can be used in existing vehicles without any modifications. Biofuels are renewable resources that are nontoxic, and biodegradable. They have reduced inflammability, and their performance is also superior. Ethanol-blended gasoline has become a commonplace fuel in many coun-tries. Ethanol, largely available as a byproduct of the sugar industry, is nontoxic and is con-sidered environment friendly, causing no harm to soil, water bodies and public health. Being an oxygenated fuel, ethanol enhances the combustion of gasoline and effectively lowers emission rates from engines.

• Natural fibers, such as coir, jute, etc., lessen the burden on the environ-ment through product substitution for similar applications such as nylon, polyes-ter, polyethylene, etc. Coir geotextiles find extensive application in preventing soil ero-sion and landslides.

• Biotechnology (BT) products can reduce the intensity of normal cropping in terms of input, such as fertilizer and water, and they have better resistance to adversi-ties to pest infection, and crop losses while increasing productivity. Several BT products help to reduce environmental footprints.

• Recycling of paper and replacing plastic with natural polymers can provide greener options. At present, 150 million tons

ENVIRONMENT


of plastics are produced a year from fossil fuels globally. Plastic products have gained universal usage not only in food, clothing and shelter, but also in transportation, con-struction, medical, entertainment, etc. There is a growing demand for biodegradable plas-tics as a solution to global environmental and waste management problems.

Research on biodegradable plastics and polymers has been carried out world-wide with the aim of achieving a balance between human activities and the natural environments. Ideal biodegradable plastics are defined as materials that are completely degraded to CO2 and water (H2O) by the action of microorganisms. Resources of biodegradable plastics and polymers are mainly classified into biosynthetic poly-mers such as poly hydroxyalkanoic acid, plant polysaccharides such as cellulose, starch, and xanthan, and chemical syn-thetic polymers such as polylactic acid, poly �-caprolactone and polyaspartic acid.

Biodegradable plastics are expected to

replace plastics derived from petroleum products in natural environment such as agricultural and fisheries, civil engineer-ing and construction materials, toys where recovery and reuse are difficult, compost-ing of organic waste is effective such as food packaging, hygienic products on account of its specific features, such as slow release, water retention, medical use, low oxygen permeability and low melting temperatures.

Green manufacturing. Green manu-facturing (GM) aims to prevent pollution and save material and energy through inno-vation and development of new knowledge that reduces or eliminates environmental damages right from the design, manufac-ture and application of products or pro-cesses. Apart from using benign materials, changing process technologies also adds to the environment friendliness of manu-facturing industries. Existing processes are also undergoing tremendous changes to become environmentally friendly. Thus,

GM requires rethinking of the manufactur-ing systems by pursuing environmentally related goals and objectives, nontraditional manufacturing processes, new marketing strategies and product design based on a life-cycle approach.

Improved catalysts increase conver-sion and yields, reduce recirculation and increase outputs. The best illustration is the development of ruthenium catalyst in place of conventional iron catalyst for the ammo-nia reaction. It helped improve conversion threefold, reduce size of plant equipment and rendered higher plant capacities viable.

In-situ generation and consumption of hazardous and toxic intermediates and thus avoiding storage and transport, is another option. An example is the man-ufacture of methyl iso-cyanate and its immediate conversion to pesticides with-out going for storages; a lesson we have learned form Bhopal.

Other sustainable improvements in reaction engineering include carbonylation

The important problems encountered in environmental management in the HPI are the lack of:

1. Incentives for continuous improve-ment in the direction of pollution reduction beyond the compliance limits of the PCBs

2. Integration of environmental con-cerns into the core of the business strategy.

3. Sufficient transparency with regard to environmental information

To effectively address the listed prob-lems and foster development of an apex-level environmental policy, incorporating clean-development strategies with these elements will be required:

1. Role of top management. The first and foremost guiding principle of an environmental policy facilitating industry growth is to ensure the unstinted commitment, involvement and action-oriented approach by top management of the organization in achieving the set environmental goals.

2. Environmental policy statement. Top management should codify its envi-ronmental commitment, values and per-ceptions in a documented policy. This policy should be relevant to organization activities, product and services, and taking into account its implications on the differ-ent stakeholders. Attempts for improving energy efficiency, resource productivity

and use of renewable energy sources and raw materials need special mention within the policy.

3. Environment, health, safety (EHS) vision statement. Every unit shall have an EHS vision statement. The statements will depend on the nature and scale of organization’s operation and will specifying its current thinking and aspirations for the future. These vision statements should adopt a national pol-lution-prevention policy that encourages source reduction and environmentally sound recycling as a first option. Also, the statements recognize safe treatment, stor-age and disposal practices as important components of the overall environment protection strategy.

4. Environmental targets. The envi-ronmental targets, i.e., the qualitative and quantitative changes attainable to more environment friendliness in the indus-try and acceptance to the community, must be clearly defined. Steps that are envisaged for minimizing environmental impacts, reducing emissions of toxic gases and those causing global warming and improving employee health, safety and pollution prevention must be specified. The target must also address achieving zero accidents at workplaces, reducing incidents of work-related diseases, and

reducing risk exposure to the employees as well as to the surrounding community. It focuses on achieving sustainable develop-ment and eco-efficiency as a new business perspective through production and inno-vation integrated environmental protec-tion, responsible product stewardship and total quality improvements. It is desirable that the environmental friendliness of the HPI industry should be through imple-menting a guided approach achieved and action plan. For this purpose, existing environmental burden imposed must be quantified by considering suitable indices for every environmental aspect.

5. Control strategies. This policy shall provide for the use of legal, financial and social instruments, which influence the behavior of companies, citizens, pub-lic bodies and authorities for achieving the objectives. Existing and innovative control mechanisms, such as statutory provisions and stipulations of the various regulatory bodies may be used. Industry may be asked to apply current BATs for pollution abatement. During the interim phase, strategy of monitoring in compari-son with set standards and penal action, wherever required, should continue. HPI plants should be operated to standards that will comply with the requirements of appropriate national and international

Addressing challenges: National environmental policy

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ENVIRONMENT


using dimethyl carbonate instead of phos-gene or CO; using solid catalysts to mini-mize waste; manufacturing petrochemicals from renewable sources; produce alpha olefins from fatty acids rather than petro-leum products; avoiding the use of toxic acids, catalysts and solvents in all applica-tions; and going for photo-catalyzed reac-tions using natural dyes as catalysts instead of heavy metals, etc.

Use of low analysis fertilizers with nutrient content sufficient only to meet the demand of the plants during the crop-ping season minimizes leaching to the environment.

Develop membrane cell process for caustic soda in place of mercury cells. This has helped the industry to ward off mer-cury contamination, and the byproduct hydrogen can be used for food-grade appli-cations. Membrane processes and pres-sure swing adsorption have come of age for physical separation of gases in place of chemical absorption and regeneration.

The harshness of chemical reaction as depicted by elevated temperature, increased concentration, high pressures, large reactor volumes, corrosion tendencies, flammabil-ity characteristics, etc., are being consider-ably reduced through technological inno-vation. Today, several reactions are being carried out under lower temperatures, pressure and concentration with improved catalytic efficiencies. The best example is again from the fertilizer industry where ammonia used to be synthesized at 350 atmospheres pressure two decades ago, has been lowered down to operate at as low as 80 atmospheres. The potential for recycling and reusing within are being exploited con-siderably, and modern plants are built with such integrated facilities.

Promote integrated complexes. Refin-eries, fertilizer, power and petrochemicals sites are themselves major investment and high-technology decisions, and, very often, these units are managed by different agen-cies and function as independent compa-

nies. Technology brings in a lot of scope for exploiting the synergy within these units and could play a major role in improving the bottom line of these units. Integration of refineries, fertilizer and petrochemi-cal plants and power generation units at the planning phase will help to drastically reduce emissions and other pollutants; thus ensuring optimized operation.

Review existing control limits for pollutants. Present standards regarding effluent discharges from industrial units are technological limits attainable through application of available technologies for abatement and control available at the time the limits were mandated. These norms are not based on long-term health effects. Revised standards based on health impacts of each listed pollutant may be developed incorporating the advancements in control and detection technologies. While doing so, care is needed so that the prescribed limits are technologically achievable and are within the means and reach of the HPI.

legislation and codes of practice. The gov-ernment shall formulate country specific BATs to facilitate continuous improve-ment in environmental management. Technically and economically feasible reg-ulatory measures, as well as nonregulatory measures are also suggested to improve environmental management in chemical processing operations. Fiscal incentives may be provided to encourage early adop-tion of technologies that reduce pollution.

6. Risk management. It is necessary that management will ensure that poten-tial health, safety and environmental risks associated with the activities are assessed early to minimize and manage adverse effects and to identify opportunities for improvement. A workable Disaster Pre-paredness and Emergency Management Plan (DPEMP) should be kept ready to mitigate any such situations in the unlikely event of its occurrence.

7. Staff training. Necessary and state-of-the-art training may be given to the concerned people responsible for environ-mental management. This should include keeping them abreast of the new develop-ments, technologies and practical tools, accident investigations, environmental impact predictions, selecting appropri-ate protective equipment, implementing emergency response plans as and when

necessary, and so on. They may be trained to learn from previous incidents and simi-lar experiences. They must be made con-versant in the corporate environmental management systems and the proposed action plans for its implementation. In short, necessary capabilities must be avail-able in-house with all organizations to tackle probable emergency situations that are likely to arise.

8. Monitoring. The policy should call for regular and meticulous environmental performance monitoring to keep track of the environmental burden imposed by the company and watch the direction of its progressing trends. Quantitative, as well as qualitative approaches, may be used for this purpose. Emissions, waste streams, hazardous waste, disturbance, resource depletion, etc., should be addressed accordingly. Commitments towards targets for Responsible Care and social responsibility may also have to be assessed.

Present operations should regularly and systematically assess the purpose for identifying and correcting any element that may put human beings, real prop-erty or the natural environment at risk of nuisance or damage and of establishing a basis of safety-related improvements of processes and products. Any new process and product, as well as any new infor-

mation of existing processes and prod-ucts, should be thoroughly analyzed with regard of HES implications. Concerned authorities must be kept well informed of the operations and of HES implications. Any incident entailing a risk of environ-mental disturbances or of conflict with existing regulations should be promptly reported to proper authorities.

9. Public information. Necessary pro-vision must be for sharing information on HES with the public and incorporated in the policy. The “community right to know” acts or the “right to information” acts in several states are intended for this. The policy should provide for involve-ment of the community and working with active environmental groups in the region in bettering the environmental situation and thereby enhancing public perception of the industry.

10. Annual reports. The policy shall call for Annual Environmental Status Reports (AESR), along with the finan-cial performance reports. Such reports are now available from many HPI operators around the world. The feedback on these reports from concerned stakeholders may be used for continued improvement of existing systems. The policy document shall be integrated with the national envi-ronmental plan of the country.

Addressing challenges: National environmental policy (cont.)

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ENVIRONMENT

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In HPI plants, normally systems are used to control and reduce emissions and discharges within the limits set by regula-tory authorities. The units do not put in further efforts for reducing the pollution effects beyond prescribed limits by the PCB in the interest of public health. This is pri-marily due to a lack of incentives encourag-ing additional investment toward improved technology. HPI operators should be encouraged to go beyond compliance and become more environmentlly friendly.

Harness environmental biotechnol-ogy. Environmental biotechnology uses living organisms—flora and fauna-engi-neered—to exhibit specific traits to iden-tify, control or prevent pollution. This technology has been applied to cleaning up hazardous waste sites more efficiently than conventional methods, thereby reduc-ing the need for incineration or extraction-based methodologies. Bioremediation has been applied to the cleanup of many dif-ferent pollutants, including heavy metals, persistent organic pollutants, explosives, sewage and industrial waste. Because of the prevalence of tropical climate, biologi-cal processes for pollution control have an edge over chemical processes and are more

efficient. Modern developments, such as recombinant and genetically engineered organisms, find extensive application in biological processes for pollution control and bioremediation.

Reduce GHG emissions. Encourage-ment through adequate financial incentives should be made available to those compa-nies intending for voluntary reduction of GHGs and other climate-change promot-ers. The extension of natural gas pipelines, harnessing clean-coal technologies, gasifica-tion of biomass and development of hydel and nuclear sources for power generation should be encouraged.

Reduce water intensity. The HPI is a highly water-intensive industry. The availabil-ity of good quality water for the community and industry will become a major problem in coming years. To address the availability of adequate water for industries, recycling and reusing process water is a potential option to pursue. Recycling and water reuse program can benefit through advanced membrane technologies, which have come of age and are now cost-effective options.

Develop pollution inventory data-base. The policy should strive to develop a national level pollution inventory data-

base. It could ensure that pollutant levels are reduced over time during the develop-ment process.

Changing role of the regulator. Envi-ronmental regulatory authorities in devel-oping countries must be encouraged to become solution providers to the industry rather than being mere policing agents.

Disposal of hazardous waste. Man-agement of hazardous waste materials is a major concern for HPI plant operators from the environmental angle. Hazard-ous waste can be solid, semi-solid or non-aqueous liquids. Because of its quantity, concentration or characteristics in terms of physical, chemical, infectious quality capable of significantly contributes to an increase in mortality or an irreversible dam-age. Left uncared or improperly treated, stored, transported and disposed wastes, they are capable of posing a potential haz-ard to human health and the neighboring environment. A waste material is classified as hazardous if it exhibits, whether alone or in contact with other wastes or substances, any characteristics such as corrosivity, reac-tivity, ignitability, toxicity, acute toxicity or infectious property. These substances are either created as byproducts of the HPI or as residues of processes. Toxic byproducts or products are capable of causing irrevers-ible damages to the environment. Most industries have identified such materials coming under the review of hazardous wastes from their operations and are sub-sequently classified.

Hazardous waste is generated in-house as a result of several industrial operations, and there are imports too for recovery of valuable metals hydrocarbons, etc. Deter-mined efforts of local governments to federal levels describe the necessity for chemical hazardous treatment and disposal facilities (CHTDF).

Emergency planning for disaster mitigation. Local level emergency plan-ning for disaster preparedness in case of natural calamities and man-made disas-ters is important. Effective mechanisms for mitigating hazards should be devel-oped under the district administration. The program may be coordinated on the lines of the Awareness and Preparedness for Emergencies at Local Level (APELL) project of the United Nations Environ-ment Programme (UNEP).

Key issues. The key issues in environ-mental management in the HPI are identi-fied as pollution from solid waste resulting in contamination of land space; liquid efflu-


ENVIRONMENT

77

ents endangering water streams and ground-water resources; and gaseous emissions degrading the quality of atmospheric air. It is a risk to life from operational incidents to people and property in the industry and adjacent neighborhoods due to the storage, handling, transport and use of large quanti-ties of inflammable and hazardous chemi-cals and hydrocarbons; large-scale depletion of natural resources, raw materials, energy resources and water; and contribution to global warming due to GHG emissions.

Studies also reveal that the units have been successful in controlling emissions from their operations to the prescribed levels by the statutory authorities and as required by law. The best available tech-nology (BAT) for pollution control and environmental management is being used, and it compares well with such practices being adopted internationally.

Generally, there is substantial compli-ance by all units to the standards prescribed for effluent discharges. Often, units are committed to attaining norms for various parameters as stipulated by PCBs. HPI com-panies will go beyond compliance if there are sufficient economic incentives to make additional investments. In other situations, no attempt is made to achieve better control of pollution and to meet the standards. HP

BIBLIOGRAPHYFor complete bibliography, visit HydrocarbonProcessing.com.

Dr. MP Sukumaran Nair is currently the Special Secretary to Government of Kerala and Chairman, Chemical Engineering Division Board of the Institution of Engineers (India).

He was formerly managing director of the state-owned chlor-alkali major Travancore-Cochin Chemicals (TCC) Ltd., Cochin. He has over three decades of experience in the chemical processing industry at the M/s Fertilizers and Chemical Travancore (FACT), India’s pioneer fertil-izer and chemical manufacturing, engineering design and consultancy organization (FEDO) and at TCC Ltd. He holds BS degrees in chemistry and chemical engineering and is a postgraduate in ecology and environment. Dr. Nair also has an MBA and a PhD in management. He has published more than 90 technical and management papers at various national and international forums and workshops and journals. He is well experienced in process plant operation, process design, troubleshoot-ing and management, in the HPI. Dr. Nair is a Fellow of the Institution of Engineers (India), was chairman of its Cochin center and a member of the American Institute of Chemical Engineers and European Federa-tion of Chemical Engineers. He is also associated with various professional bodies and institutions and serves on several expert advisory committees to the Central and State Governments. A recipient of the Outstand-ing Chemical Engineer award from IIChE, he is listed in the Marquis, Who’s Who in the World and by the International Biographical Centre, Cambridge, England.He can be reached at [email protected].

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ROTATING EQUIPMENT


Over the years, petroleum refineries around the world have researched and invested in ways to reduce the amount of waste energy and pollutants produced and released

into the environment from their processing operations. The diverse processes used to produce crude oil based products usu-ally require large amounts of electricity to run the various com-pressors and pumps.

Many oil refineries have projects to recapture the energy as part of their cost savings plan and are driven by environmental concerns to reduce pollutants generated by process units. The hot gas expander is a single-stage power turbine capable of converting the potential energy of flue (waste) gas into mechanical work. This article describes how refineries can “go green” by implementing fluid catalytic cracking (FCC) hot gas expanders.

Highlighting the FCC process. The FCC process is widely used for manufacturing of gasoline and petrochemical feed-stock. The process uses three main process vessels: the reactor, fractionator and regenerator. As shown in Fig. 1, feedstock (crude oil) enters the FCC reactor; here, a catalyst strips carbon molecules from the larger hydrocarbon chains in the feed oil. This reaction breaks the hydrocarbons down into smaller, more useful hydrocar-bon products. The hydrocarbon mixture is sent to the fractionator where it is vaporized and cooled under controlled conditions to

various levels. The process allows desirable petroleum-oil refinery products to be separated out.1,2

The final portion of the FCC process is the regenerator. The used (spent) catalyst from the reactor is sent to the regenerator to be stripped of carbon and recycled back to the reactor. Compressed air is pumped into the regenerator to mix with the used catalyst in a combustion process. Also taking place in the regenerator is the separation of particles from the flue gas. There are generally two stages of cyclones in the regenerator that strip the exhaust gas of its catalyst. The flue gas exiting the top of the regenerator will typi-cally pass through an additional vessel called a third-stage separator (TSS) to further reduce the catalyst amount in the flue gas.

The flue gas from the FCC process exiting the regenerator has significant pressure, temperature and volume, and it is a source of useful energy that represents an energy cost-saving opportunity to a refinery. One method of harvesting the potential of the flue gas is a heat recovery steam generator (HRSG). The HRSG uses the heat from the flue gas to create steam. However, this method ignores the pressure component, a potential energy source that can be converted to mechanical work.

A second method is to use an expander to recover energy from the flue gas. This energy can then be used to drive the compressor that provides air to the regenerator (the main air blower) or an electric generator.

Going ‘green’ with FCC expander technologyNew options recover waste gas energy as steam and electricity for plant use

B. CARBONETTO and P. PECCHI, GE Oil & Gas, Florence, Itlay

Rege

nera

tor

(1,3

00°F

-1,4

00°F

)

Reac

tor

(920

°F-1

,050

°F)

Powerrecovery

Flue gas

ElectricitySteam

Spentcatalyst

Regeneratedcatalyst

Air

Fuel gas

LPG

Gasoline

HCN (gasoline)

LCO (diesel)

Clarified oil (fuel oil)Raw oil: VGO,resid, etc.

Frac

tiona

tor

Flow diagram of FCC unit.FIG. 1 Hot gas FCC expander—side view.FIG. 1A


ROTATING EQUIPMENT


In this case, the FCC process is the existing (and primary) process and it can be useful to think of the power recovery system as a secondary process (see Figs. 1 and 2). The refinery operator is primarily interested in the FCC process. It is the FCC process that generates the refinery primary products (gasoline, propane, fuels, etc.) and, thus, it yields revenues for the refinery. The power recovery process increases energy efficiency for the overall plant and therefore, it increases profitability.

Hot gas expanders can be used to drive the compressor that provides air to the regenerator—the power recovery train (PRT). Alternatively, it can be used as the driver for stand-alone expander-generator sets. Fig. 3 shows a main air blower PRT; Fig. 4 illustrates an expander-generator set. In both cases, the expander maximizes recovery of available energy from the flue gas.

Main air blower train. A main air blower PRT consists of a steam turbine, compressor, motor/generator and expander. The expander in the PRT is used to drive the compressor, and often supplies additional power for the generation of electricity. In this case, the expander cannot provide all of the power needed to drive the compressor; motor/generator will operate in motor mode. A steam turbine is used for startup.

Electric power generation train. Expanders in an expander-generator application drive a generator, thus using the

entire power production to generate electricity for the refinery. In general, the expander–generator set stands to benefit the customer the most. The key benefits include:3

• Easily added to existing FCC installations• Small footprint• Installed remote from the FCC unit or main air blower train• Does not need to match the air blower operating

conditions—speed• No modifications to the air blower equipment• Installed during FCC operation and tied in at a scheduled

turnaround• Taken on- or off-line at any time without affecting FCC

unit operation• Has a high efficiency due to equipment optimization.

FCC expanders: Description and operation. Fig. 5 represents an FCC hot gas expander; it shows the path of the hot flue gas flow passing through it. Major components can be seen assembled in Fig. 6. The FCC hot gas expander is a single-stage axial-flow turbine. The pressurized, high-temperature flue (exhaust) gas coming from the FCC process enters the inlet opening of the expander and is accelerated through the stationary and rotating blades. In the expander, the pressure and temperature are reduced, and energy is extracted and converted into mechanical work.

Although the flue gas has been processed through multiple separation stages, a significant amount of catalyst particles will

Expander generator power recovery system for an FCC Plant.

FIG. 2

Expander generator set. FIG. 4

Main air blower power recovery train. FIG. 3 Cross-sectional view of the FCC hot gas expander (flue gas flow path).

FIG. 5

ROTATING EQUIPMENT


remain in the flue gas. The catalyst particles pass through the expander and can potentially cause erosion. The expander flow path’s stationary and rotating components are optimized to efficiently extract the pressure energy from the flue gas and to minimize catalyst erosion.4 Rotor disc cooling and seals are used to increase the service life. The latest developments in material alloys and coatings can be used to mitigate damaging effects from handling catalyst-laden flue gas. All components are designed for reliability, including casings, bearings and supports. All of these factors allow the expanders to regularly withstand four to five years of continuous operating cycles.

Based on process conditions (pressure, temperature and flow), a customized flow path has to be selected to meet the process requirements. Selecting the right expander frame size is

very important, and standardized frames that can cover a large range of pressures and flows have been developed, as shown in Fig. 7.

History of expanders for FCC applications. Initial expander development took place between the late 1950s and the mid-1970s. In all, hundreds of units were installed, each with unique designs for specific installations. Second-generation expanders were developed from the mid-1970s through the mid-1980s, and this era experienced significant expander production. Hot gas expanders became available with increasing frame size options. However, there were also increased industry concerns regarding equipment reliability as well as the desire to increase the time between shutdowns.

Some of the initial problems/issues faced during the develop-ment of expanders over the decades included:2

• Lack of proper catalyst separation mechanism. The expander flow path components would wear quickly due to the catalyst content in the flue gas. The introduction of an addi-tional catalyst separator (external to the regenerator) commonly called the TSS was crucial to extending the life of expander components.

• Lower refinery throughput factors such as lower pres-sures and temperatures meant lower power recovery opportu-nities for refineries

• Difficulties of designing customized expanders for every FCC application. As every refinery designs and operates their FCC unit differently, each expander needed to be custom-ized. Only a few expander manufacturers had the capabilities to design custom solutions. To overcome this issue, pre-standard-ized frames were developed to cover refineries’ production needs (see Fig. 7 for sample chart).

• Validation of investment cost vs. benefits over the years. Initially, during the earlier developmental years (1960s and 1970s), it was not essential to install an expander since pollu-tion-control measures were not given as much priority as they are today. As more government laws have targeted pollution control and green initiatives, more refineries are investing in ways to reduce their power consumption.1

Over the last 20 years, design programs have been developed to address the user industry’s increased emphasis on expander

reliability and extended time between shutdowns. These programs focused on material upgrades, CFD-designed flow paths, more efficient catalyst removal and robust control systems. Modern FCCU hot gas expanders are designed to run for four to five years to coincide with FCC unit maintenance intervals and have dem-onstrated this capability in many applica-tions.

Economic benefits of power recovery. Energy costs are a major part of the total costs of operating an oil refinery, and electricity usage is a large part of these energy costs (steam is an alternate energy source), with energy requirements ranging from 50 MW to 180 MW. FCC expanders can help reduce these costs even if the tem-perature drop that is experienced through

0 50 100 150 200 250 300 350 4001.0

1.5

2.0

2.5

3.0

3.5

Flue gas flowrate, lbs/sec

Pres

sure

ratio

FEX-81 FEX-97 FEX-107 FEX-125 FEX-142

22 TBD 40 TBD 55 TBD 75 TBD 110 TBD

Refinery capacity: TBD = thousandsbarrels per day

Frame selection chart.FIG. 7

Cross-sectional view of the FCC hot gas expander (major components).

FIG. 6

ROTATING EQUIPMENT


the FCC expander will result in decreased steam production for the refinery. Due to the variability of refinery steam requirements and HRSGs, the reduction in steam temperature and production is not easily quantified. Additionally, a loss in the quantity or temperature of the steam does not easily translate into a monetary figure. These values must be evaluated based on the specifics of the application. However, a very rough approximation can be made based on actual cases.

The expander reduces the flue gas temperature entering the HRSG by approximately 300°F. For a typical HRSG, the exit flue-gas temperature will be the same with or without an expander. Thus, the flue-gas temperature reduction through the HRSG will be 300°F. To maintain superheated steam pro-duction, the amount of steam produced will be less when an expander is used.

Table 1 shows the estimated savings in electricity per year attributable to a power recovery unit installation. The notable savings due to higher power recovery are evident in comparing current process conditions (2007) to those of the 1960s.

Factors taken into consideration for Table 1 values include:• Steam generation losses (flow and temperature) may be

experienced and must be debited• Installed cost is approximately $30–$55 million• Typical payback is less than three years.

Environmental benefits of power recovery. In a power recovery system installation, there are environmental benefits associated with the economic benefits to the refinery. The positive impact on the environment comes from the fact that the need to install sources of electricity to run machinery is reduced, with the consequent elimination of the emission of carbon dioxide (CO2), nitrogen oxides (NOx) and other pollutants associated with the combustion of fossils fuels.

Often, the energy usage and efficiency of a refinery is measured through the Energy Intensity Index (EII). The installation of a power recovery system can reduce a refinery’s EII by 7%–10%, thus helping them to reduce their environmental impact and to comply with specific regulations.

A few numbers can give a better understanding of the huge benefits of this solution. For example, if we consider the total installed fleet of one leading manufacturer’s FCC hot gas expand-ers, the estimate is that it produces around 500 mega watts (500 MW) of power, which corresponds to 4.3 billion kWh (4.3 TWh) of electricity saved per year. Using the US Environmental Protec-tion Agency (US-EPA) Emissions Calculator, 4.3 TWh of electric-ity saved per year translates into approximately 3.1 million metric tons of CO2 emissions avoided per year.5 In simpler terms, this is equivalent to:

• Annual greenhouse gas emissions from 565,000 passenger vehicles

• CO2 emissions from 350 million gallons of gasoline consumed

• CO2 emissions from the electricity used by 428,000 homes in one year

• Carbon sequestered annually by 702,000 acres of pine or fir forests.

As can be seen, the installation of FCC expanders in refineries has a noticeable environmental impact.

Outlook. As the petroleum refining industry continues to strive for more ways to save energy, reduce costs and improve the envi-

ronment, more innovative ways will be pursued to deliver more benefits to customers. FCC hot gas expander technology has grown significantly from the 1960s to the present, and it now offers state of the art machinery that can be incorporated into the refinery process without impacting plant reliability or efficiency. The huge economic and environmental benefit of this energy recovery solution proves that FCC hot gas expanders are a sig-nificant contribution in the drive for “green” applications in the oil and gas industry. HP

LITERATURE CITED 1 US Environmental Protection Agency Executive Summary, 2008 Sector Strategies Performance Report, Executive summary, http://www.epa.gov/ispd/ pdf/2008/executive_summary.pdf 2 Bloch, H. and C. Soares, Turboexpanders and process applications, First Ed., Gulf Publishing Company, 2001, ISBN 0-88415-509-9. 3 Conroy, C.F and D. H. Linden, “Successful Application of Stand-alone FCCU Expander / Generator Sets,” International Symposium on Turbomachinery, combined-Cycle Technologies and Cogeneration – IGTI-Vol.1. Greenhouse Gas. 4 Carbonetto, B. and G. L. Hoch, “Advances in Erosion Prediction of Axial Flow Expanders,” Proceedings of the 28th Turbo machinery Symposium, Turbomachinery Laboratory, Texas A&M University, College Station, Texas, pp. 1–7, 1999. 5 Equivalencies Calculator, 2009. US Environmental Protection Agency, (http://www.epa.gov/cleanenergy/energy-resources/calculator.html).

TABLE 1. Potential recovered power and savings

YearDesign conditions 1962 2007

Inlet temperature–Basis: the assumption 1,100 1,400of a 25 degree drop from the regenerator, °F

Inlet pressure–Basis: the assumption of a 13 504 psi drop from the regenerator, psig

Discharge pressure, psig 1.5 13

Flow, lbm/hr 200,000 1,750,000

Delivered power, kW 6,340 52,944

Electricity savings–Basis: average electricity $3,332,304 $27,873,366cost of 6 cents/kW-hr

Ben Carbonetto is hot gas expander product leader, GE Oil & Gas. His career spans 15 years in the design and operation of turbomachinery, starting in 1995 as an axial compressor / hot gas expander design engineer. In 2001, he was promoted to Sr. (lead) design engineer, a role which expanded to include responsibility

for orders, engineering and execution as expander product supervisor/manager. Mr. Carbonetto has also served as engineering manager (2005) and North America ser-vices engineering manager (2007). He holds a BS degree in mechanical engineering and mechanics from Drexel University and is a member of ASME.

Paolo Pecchi joined GE Oil & Gas in 1996 as a fluid dynam-ics engineer with the R&D team. In 1998, he joined the technical leadership program (TLP) covering different technical assignments in the gas turbine department, following LM2500+ HSPT product introduction and field installation. Upon TLP graduation, he held

the role of project/system engineer in the new product Introduction organization, and in 2004, he was appointed NPI-NTI programs management leader, being responsible for the management of the company’s technical development programs. In 2008, he relocated to Bethlehem, Pennsylvania, as manager of the engineering team. Mr. Pecchi is now the global technical fleet support manager—turbomachinery. Mr. Pec-chi graduated with a degree in mechanical engineering in 1995 from the University of Florence, Italy.

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ENGINEERING CASE HISTORIES


A new plant was constructed; it contained over 10,000 socket welds. Socket welding (Figs. 1 and 2) is one of a number of methods used for making piping connections; they are

plain-fillet welds arranged for greater ease of alignment and weld-ing. Used for nominal pipe sizes (NPSs) 4-in. and smaller, they are favored for new projects that make use of prefabricated piping.

However, there are some downside issues with socket welds. Having only about ⅓ the strength of a full butt weld in bending and even less in fatigue, they are not considered high-strength welds. Moreover, socket welds are subject to vibration cracking in the root and toe regions and are susceptible to crevice corrosion, if used in the wrong services.

Assessment of the weld. X-ray examination indicated that some socket welds lacked adequate weld penetration of the fillet weld. Also, some of the pipes had bottomed out in the socket body, which was due to poor workmanship when assembling the pieces for welding. When welding these assemblies, there is an ASME Code requirement for a gap. Such a gap, usually 1⁄16 in., ensures that the weld is not stressed due to the pipe axially expanding. Without a gap, there is the possibility of a weld crack developing in the root.

It would have been extremely cost prohibitive and, in some cases, impossible to inspect, grind and reweld all the joints due to the confined nature of the piping after installation. There was simply no room for the needed access. The project team, therefore, proceeded with a risk analysis approach. This meant that noncriti-cal, nonhazardous joints that weren’t safety issues would be consid-ered low risk and would be checked for leaks during normal pipe inspection intervals after startup. Higher risk joints that could pull apart were either rewelded or braced, depending on the assessed risk. This reduced to a manageable number of joints subjected to repair; after 10 years, there have been no major leaks.

With no gap during welding, strain will be induced in the weld root. Weld-root behavior and what happens to stresses as the weld cools would be complicated and was not considered. But many of these types of no-gap welds were checked after welding, and no cracks were present.

Problems in normal operations. Another potential problem is no gap during normal operation. The problem then becomes how much the weld is stressed due to a temperature difference between the socket body and pipe. Any additional stress would reduce the load capability of the weld. This would be important to know for the screening procedure.

This was analyzed with a coupled thermal stress finite-element analysis for a 400°F product flowing through the pipe and with no end gap. Weld stresses were less than 5,000 lb/in.2 and should

not affect the life in non-vibratory services due to bending. Con-cerns with no gap were not considered further in the risk analysis.

Best preventive measures. While this article is for edu-cational purposes only, it does show the importance of using various methods to solve problems in a cost-effective manner. A high level of experience allowed the project team to quickly examine the various joints on piping drawings and to make key decisions. The resulting savings in time and expense were well worth the effort. HP

Case 60: Socket-weld failuresA risk analysis can determine which critical welds to repair

T. SOFRONAS, Consulting Engineer, Houston, Texas

Dr. Anthony (Tony) Sofronas, P.E., was worldwide lead mechanical engineer for ExxonMobil before his retirement. Informa-tion on his books, seminars and consulting, as well as comments to this article, are available at http://mechanicalengineeringhelp.com.

Fillet weld toe

Gap

Pipe

Body

Root

Socket-weld nomenclature.FIG. 1

Dye-leak trace of a 2-in. socket-weld connection.FIG. 2


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HPIN CONTROL

[email protected]

PIERRE R. LATOUR, GUEST COLUMNIST

HPIN CONTROL

I followed my April 2010 call for renewal of process control and IT practice with editorials on purpose in August, performance in October and consequences in December. Now I turn to selec-tion of controlled variables (CVs).

How do we select CVs? Well, just how do we go about select-ing operating conditions to be controlled about setpoints by manip-ulating valves? Why we do select particular flows, levels, pressures, temperatures, compositions, efficiencies, capacities and yields for measurement and stabilization about desired setpoints near limits? How do we determine the production, inventory, product quality, utility consumption and equipment limit setpoints? From the host of candidate refinery operating conditions, what is the underlying basis for selecting a relatively few for control to operate the HPI?

We know how to measure CVs. We know how the manipulated valves affect them. We know about instruments, control algo-rithms, models, optimizers and displays. Somehow, we determine what is important, what we care about and what counts. Since we know how much equipment costs to procure, install and maintain, we proceed to engineer and use instruments, control systems, computers and IT to operate about predetermined CV setpoints.

But why? What is wrong with this picture? What is missing? Why is it so hard to rigorously quantify the financial value of improved HPI operation? Why do we have so much trouble jus-tifying maintenance? How do we figure out the merit of control and information system components and solutions?

Pause a moment to think about how we know and quantify values. We determine what is important, what we care about, what counts. What we mean is that the average of a candidate CV affects profit rate. Profit is sensitive, and errors can be costly. There is great potential from quantifying the steady-state profit rate increase as the mean is moved to a limit, determining the pre-cise location value for that limit, and the financial consequences for exceeding that limit. Establishing this tent-shaped tradeoff is critical for selecting CVs at the outset and controlling them. If the sensitivity is low and the profit tent shallow, the CV is not important. If sensitivity is high and the profit tent steep, the CV is important. We select CVs/key performance indicators (KPIs) because they have interesting and significant trade offs.

Significance. Often, there is a severe cliff at the limit, encoun-tered when a machine, safety, government or customer penalty is incurred. CVs that encounter high cliffs are critical. Knowing the location, slope and height of those cliffs is central to the busi-ness of HPI operation. So, one should determine and maintain the steady-state profit rate cliff function of CVs as a first order of business for operating properly and selecting the appropriate CVs for doing so. If you do not know CV/KPI cliff limits, you do not know your operating business.

This function can be combined with the CV distribution to determine the actual expected value profit hill to find the best setpoint to optimize each risky tradeoff. This is the profit meter for every CV/KPI. If there ever was an activity that needs to pay close attention to identifying, capturing and sustaining financial values by locating and re-optimizing risky tradeoffs, it is the HPI.

Once the best practice of process control is driven as the stan-dard method for operating HPI plants, the determination of the value of control components becomes routine and we know the value of our work. We know the information that we need to make best decisions, and we can make them faithfully on the best information available because we know what we are doing with that information. Now we have a complete method for selecting CVs and KPIs. We know how to pick them and why.

Distillation dual temperature control? Kern,1 Fried-man, Shinsky and I agree that tightly controlling top and bottom temperatures or dual-ended compositions is not a good idea. Beyond their technical arguments, my additional reasons stem from HPI separation business economics.

For separations like distillation, absorption and extraction, one key component is invariably more valuable than the other, providing the incentive for their separation. There will be a maxi-mum specification for the less valuable component in the valuable stream and an optimum recovery vs. utilities for the valuable key in the less valuable stream. One end invariably has an important customer-quality specification, while the other has a smooth recovery vs. utility financial tradeoff. The former hard target is best controlled by material balance split; the latter soft target by utility reoptimization when feed composition, feedrate, compo-nent value or utility costs change. The economic incentive for tight soft-target control for a nearly flat profit hilltop can be quite small. This situation is true for olefin plant cold-side recovery, aromatics recovery, refinery saturates and unsaturates gas plants, crude-oil distillers and natural gas plants.

So, first, ask why control temperatures at both ends simulta-neously? What is the financial merit? How should their setpoints be determined to align the column operating conditions to its economics? Avoid working on control systems that don’t make much money. HP

LITERATURE CITED 1 Kern, A., “Weighing in on dual-temperature control,” Hydrocarbon Processing, Vol. 89, No. 11, November 2010, p. 15.

Process control practice renewal—select CVs

The author, president of CLIFFTENT Inc., is an independent consulting chemical engineer specializing in identifying, capturing and sustaining measurable financial value from HPI dynamic process control, IT and CIM solutions (CLIFFTENT) using performance-based shared risk–shared reward (SR2) technology licensing.


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Hydrocarbon Processing January 2011