Process Industries Innovation through Electrotechnology

ELECTRIC POWER RESEARCH INSTITUTE

Process industries such as food, textiles, paper, chemicals, and petroleum are vital to the Ameri- can economy. The process industries are major users of energy in general and of electric- ity in particular-using nearly half the electricity consumed by the entire manufacturing sector.

The EPRl Industrial Program is promoting the more efficient use of electricity (and of energy) in the process industries through the development of innovative electric technologies and meth- odologies. EPRl's work with the process industries has led to involvement in two related areas-the agricultural sector, and waste and water treatment. EPRl is committed to helping the utilities-and their process industries customers-meet pres t and future energy needs i J. * T

in environmentally and economically acceptable ways. -_

Electricity Consumption

Motor drives are the predominant user of electricity in the process industries, accounting for nearly 80% of the total electricity con- sumed. Most motor drives are used in "prime movers" (pumps, fans, and compressors); they are also used in materials processing (mixers, grinders) and in materials handling (cranes, conveyors). Heat pumps, increasingly common in the residential and commercial sectors, are an obvious application for industry as well-especially for the process industries. Heat pumps recover waste heat and then use compression to elevate its tempera- ture for subsequent use; the com- pressors are typically driven by electric motors. Similarly, electric

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Energy Used in Manufacturing, 1985

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Metals Materials Process Industries Production Fabrication

The process industries consume almost as much electricity as the metals production and materials fabrication industries combined. Of the 345 billion kilowatt-hours of electricity consumed in 1985 by the process industries, the chemicals industry used 41 %, paper 25%, food 14%, petroleum 12%, and textiles 8%. Source: Electrotechnology Reference Guide, Rev. 1, August 1988.

motor drives run the pumps and compressors that are the basis of freeze concentration. Freeze concentration removes heat from a liquid mixture until one compo- nent (typically water) crystallizes; these frozen crystals can then be removed, leaving behind a con- centrated version of the original mixture. In another promising separation technique-mem- brane separa tiom-e I ect r i c motors typically power the high

ocess

American industries can be grouped into three categories: metals production, materials fabrication, and process indus- tries. This classification is based on common characteristics of

tries and on tradition.

icals, and petroleum duce commodities

in large plants primarily using continuous, round-the-clock processes-hence the term

because they provide raw materials crucial to other indus- tries (for example, the PVC used

y the aircraft, auto-

I Motor Drives (incl. ASDs) I J 1 J I J

pressure pumps used to force the fluid mixture against the membrane.

Electrochemical processes for the separation and synthesis of chemical species (electrolytic separation and electrochemical synthesis) were among the earliest industrial applications of electricity and have been eco- nomically significant since the turn of the century.

Electricity is underrepresented in process heating. Only a fraction of one percent of the 2,000 trillion Btu used to heat, cook, soften, melt, distill, cure, and fuse mate- rials and products in the process industries is now provided by electricity. However, innovative

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electric technologies-such as radio frequency (RF), microwave (MW), infrared (IR), and ultraviolet (UV) processes-have already found a variety of applications, and many new uses for these technolo- gies are under development.

These various electrotechnologies typically share certain significant advantages. Compared to their conventional (e.g., thermal) counter- parts, they offer:

I reduced energy use

I increased productivity I improved product quality

I compactness, and

I environmental cleanliness

Food and Agriculture

The most promising of the new electrotechnologies in the food industry is freeze concentration. EPRI, along with Dairy Research, Inc. (DRINC), is sponsoring a major development effort on freeze concentration of dairy products. Dairies, the largest user of energy for product con- centration in the food industry, currently use steam-driven evaporators to concentrate milk products. Freeze concentration lowers energy costs dramatically, while offering a variety of new and improved products. Frozen concentrated milk, for example- similar in concept to frozen orange juice-has a long shelf life and can easily be reconsti- tuted to produce fresh-tasting whole milk. In addition, the taste of powdered milk can be im- proved, and better use made of milk by-products. Whey-the most important of these by- products-is now discarded; via freeze concentration, pharma- ceutical grade lactose and valuable whey protein concen- trate could be produced from this now-wasted whey.

Dielectric processes (MW and RF) are also gaining popularity, as a means of cooking, heating, and drying a diverse group of food products. Dielectric proc- esses heat very quickly and uniformly. Because they tend to heat water molecules first, dielectric processes are often used to dry foods such as cookies, crackers, and cereal in which precise control of final moisture content is important.

An R&D project cofunded with several California utility compa- nies was undertaken by the California State University at Fresno to enlarge the market for California seedless grapes. Using MW energy under vac- uum, grapes were dried to provide a tasty, crunchy, nutri- tious snack food unlike any products commercially available.

Free+ concentration removes heat from a liquid mixture until one component (typi- eaily water) crystallizes, these frozen crystals can then be removed, leaving behinda concentrated version of the original mixture /I is a less expensive process than evaporation, and nearly eliminates fhe negative side effects typically resulting from heating the product

In addition to producing "grape puffs" retaining the shape, color, and taste of the original grape, this technique is applicable to many other fruits and vegetables.

Another project, underway at the EPRI-sponsored Dielectric Heating Laboratory at the Univer- sity of Texas, is exploring the

application of MW and RF heating to kibbled pet foods. The goals of this project are to precisely control the moisture content of the final product and to increase the dryer throughput.

Along with the National Rural Electric Cooperative Association (NRECA), EPRl is sponsoring the National Food and Energy Council (NFEC) in a three-year research

effort. This project is designed to develop electrotechnology appli- cations in large-scale agriculture, increase electrical efficiency, improve product quality, and en- hance productivity. This effort, to be conducted by researchers at leading agricultural universities, will focus on electrotechnologies (such as dielectric drying of farm crops), load management, and power electronics which can be quickly and economically adopted by innovative farmers.

H Several other promising electrotechnologies with applica- tions in the food industry are under consideration. Membrane separation processes are finding a wide variety of applica- tions, ranging from production of low sodium water for soft drinks to reclamation of valuable products such as corn syrup and sugar from waste streams. Aseptic processing and packag- ing of foods by conduction is presently under development; it avoids the overcooked texture and underflavored taste that often result from conventional sterilization methods. Another technology, the wafer knife-r waferjet-slices meats, fish, frozen foods, etc., with a sanitary stream of water pressurized to 40,000 psi forced through an ultrafine nozzle; the waterjet allows cutting in any contour and minimizes waste.

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Three electrotechnologies have shown promise in the paper industry TMP/CTMP instead of kraft pulping 0, and the addition of impulse drying and electric IR drying in areas @ and @

Pulp and Paper

Pulping-the conversion of wood for papermaking-is now done primarily via the kraft process, a chemical process that softens wood chips under high pressure and temperature in a sulfur- based chemical bath. Electricity plays a key role in new proc- esses for environmentally sound and less expensive pulp and papermaking.

Thermomechanical pulping is now the fastest growing sector of the pulp and paper industry. Thermomechanical pulping (TMP) and chemi-thermo- mechanical pulping (CTMP) pretreat pulpwood thermally, chemically, or both before it is ground. This presoftening enables the fibers to separate

01983 Technical Association of the Pulp and Paper Industry Inc .-___ -~ ~~ ._ ~ _ _ _ _ _ _

more easily during grinding and refining. TMP/CTMP yield is about 97%, compared to a yield of only 50% with the conventional kraft process. TMP/CTMP processing generates little or no black liquor, thereby avoiding the costly cleanup of the sulfite and sulfide waste streams that result from kraft pulping. Capital costs are about 40% of equivalent kraft process plants. TMP/CTMP refiners are large electricity users; typical refiners used in newsprint plants use 2,200 HP electric motors.

H Impulse drying, although not yet commercialized, is also promising. In impulse drying, press rolls are heated to about 700°F by induction or electric IR heaters. Paper is in contact with the hot metal roller under pressures of 400-700 psi for 15 to 100 milliseconds. By virtue of accelerated heat and pressure,

impulse drying has the potential to reduce the energy require- ment for the initial drying step by as much as 75% and the number of calender rolls by 50%. In addition to these energy and equipment savings, impulse drying can improve the tensile strength of the paper by as much as 35%.

4 “Moisture profiling” ensures that moisture is evenly distrib- uted in the paper. Use of high intensity electric IR-40 kilowatts/ foot-for moisture profiling improves paper quality, reduces steam consumption, and in- creases productivity. IR is also used to dry glossy coatings on paper.

Textiles

Innovative electrotechnologies can help increase product quality, reduce labor, and im- prove process efficiency-steps the U S textile industry must take if it is to retain its market share in the textile world Several signifi- cant opportunities exist in wet processing-including RF and IR drying of the sizing material during the slashing operation, RF drying of wet dyes in both the yarn and fabric stages, and membrane separation processes for-recovery of spent dyes

Many textile fibers-especially wool and synthetics-are ad- versely affected by excess thermal processing, losing much of their tensile strength and resilience when heated. EPRI, slog with the TVA, is sponsoring

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a project at Auburn University to test the effectiveness and efficiency of RF and IR drying during the slashing process to produce high quality warp yarns with increased weaving strength. The project is also optimizing equipment designs and conducting economic and market analyses of the domestic textile industry.

Membrane separation is used to recover spent dyes from waste streams. This has dual benefits- recovered dyes can be reused, and pollution is reduced.

EPRI is planning to expand its research activities at the leading textile schools in the country. The activities will focus on additional process heat applications, energy conservation, and automation technology.

RF drying directly heats and evaporates water molecules. Because the material- fiber, yarn, or woven goods-never contacts heated surfaces, thermal degradation is eliminated, thus improving the quality of products made from wool (as shown above) and from synthetic fibers.

Petroleum and Chemicals

The petroleum and chemicals industries both involve convert- ing complex molecules into finished products through physical separation and through chemical conversion (changing molecular structure). Chemical production is the largest indus- trial consumer of electricity and also ranks first in total energy consumption. Refining, also, is extremely energy-intensive. It is the fifth largest industrial con- sumer of energy, but most of the energy is supplied by in-house, by-product fuels. However, electricity use in refining has been expanding gradually for decades, because of the higher severity processing required to convert crude oil to higher valued clean products.

Because of the similarities be- tween refinery and chemical plant operations-and the envi- ronmental constraints they are now facing-many of the same electrotechnologies are being adopted by both industries (e.g., variable speed motor drives, heat pumps in distillation and evaporation, and membrane separation equipment).

A case study of industrial process refrigeration systems in ethylene plants was part of a two-year project conducted by Union Carbide Corp. Applica- tion/design guidelines are recommended for fast payout -4 process modifications useful in both grass roots and retrofit projects.

APLUS (Analysis of Plant Utility Systems) software has been developed to create flowsheets for industrial steam/ power networks. This software also generates both technical computations (heat and material balances) and economic compu- tations (marginal energy costs)

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hangers. Optimum design-of heat exchanger r, has been difficult, because of the complexity and of possible process configurations. Pinch tech- ly new methodology-has revolutionized process

ncept of the pinch point, known to powerplant ifferential temperature constraint in designing heat

recovery boilers, is broadened in pinch technology to include an entire plant’s heating and cooling requirements. Pinch technology is based on fundamental thermodynamic principles and universally

all industrial processes.

mps are one of the several mechanisms for enhancing proc- n. Others include improved heat recovery, proper

refrigeration levels, decentralized heat and power sys- roper integration of fired heaters.

g-particularly mechanical vapor recompression-is used to improve process efficiency and hence the yield, oughput, and fuel efficiency of refinery and chemical ons. EPRl IS currently sponsoring pinch analysis case

diks at 12 industrial sites, including four refineries and two chemi- plants. Optimized process integration-of which heat pumps are

ey component-is expected to result in a 20-40% energy reduc- tion with a 2-year payback period.

HOT COMPOSITE

D COMPOSITE CURVE

PROCESS ABOVE PINCH

PROCESS BELOW PINCH

PROCESS PINCH

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ch technology focuses on the interface nce of the process on the one hand, and the heat exchanger network and the tility systems parameters on the other hand In addltion to provldmg the apability to deslgn mdw/dual processes in fhe context of total site Issues, inch technology has proven effective m retrofits of existing operations.

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useful in optimizing existing plant _’ performance and forecasting the

net impact of project and proc- ess changes. Several oil and chemical companies are working with local utilities to apply APLUS to their plants.

W HPSCAN (Heat Pump Screen- ing Analysis) software has also been developed. This software uses pinch technology to assess the feasibility of potential heat pump installations.

W Freeze concentration tech- nology is being developed in partnership with a commercial chlor-alkali manufacturer and two utility members. In a demonstra- tion project, sodium hydroxide and potassium hydroxide will be concentrated to commercial specifications.

W EPRl’s newly published Indus- trial Heat Pump Manual assesses the current state of the art with respect to technology, commer- cial track record, and future potential.

W Cool storage technology is being examined in a refinery for sulfuric acid alkylation. Chilled liquid is produced and stored during off-peak hours, ready for use during peak daytime hours.

Pressure swing adsorption is under examination in a pilot study to recover hydrogen from refinery cat cracker gas for use in hydro-treating units. If this application is successful, valu- able by-product molecules will be recovered, and cat crackers constrained by gas handling capacity will be debottlenecked.

Refineries and chemical plants are comflfex systems that can achieve &ic$ficant energy savings through optimized process integration and the strategic application of industrial process heat pumps.

W Electro-membrane technology and electro-ion exchange tech- nology are being evaluated for purifying process makeup water and dewatering fermentation products in pharmaceutical plants. These technologies use electrically charged particles rather than purchased chemicals or process heat to separate solids from water, resulting in better product quality and lower manufacturing costs.

Waste and Water Treatment

Economically and environmentally sound methods for the management of waste-especially waste water- are the focus of a great deal of attention in industry today. The amount of liquid waste being generated is steadily increasing at the same time that environmental protection regulations are being tightened. Presently the most common methods for liquid waste treatment involve separation of solids from waste waters through chemical precipitation, sedimenta- tion, screening, and settling. How- ever, these methods are becoming increasingly inadequate. Two promising electrotechnologies for liquid waste treatment-freeze concentration and reverse osmo- sis-are emerging. EPRl is playing a crucial role in enabling existing plants to meet the new government standards and, hence, to remain operational.

W EPRl is working with an equip- ment manufacturer, the American Plating Institute, an electric utility,

and a state pollution control agency on a demonstration of freeze concentration in treating wastewater in a metal plating facility. This technique has the potential for economic recovery of useable and valuable plating metals.

W Reverse osmosis is the most popular technology today for the desalination of groundwater and seawater in order to produce potable water for municipal water systems. One of several advantages is that reverse osmosis equipment can be housed in a small building, unlike evaporation systems.

W Adjustable speed drives (ASDs) are increasingly being used for municipal water pump- ing. With electronic ASDs, motor speed on the pumps can be set to meet the fluctuating daily demand for water, thus saving energy by providing motors with only as much power as is necessary.

Electric motor drives power the pumps used in wastewater treatment plants such as the one shown here. Innovative electrotechnologies-such as freeze and membrane separation-are gaining popularity in industrial waste reduction.

Technology Transfer

In addition to developing innova- tive electrotechnologies, EPRl recognizes the need to dissemi- nate the results of its technologi- cal efforts so that they can be applied broadly across the industrial sector. The modes for technology transfer range from publications to focused work- shops to videos. Specific tech- nology transfer activities for the process industries include:

H Business Sector Workshops for utilities serving the food, pulp and paper, textiles, chemicals, and petroleum industries.

H TechCommentaries on freeze concentration, membrane sys- tems, pinch technology, indus- trial heat pumps, dielectric drying( Wand RF), and electric IR Qryfirl , p T of paper. H TechApplications on MW drying of food, textile fiber drying, and results of pinch technology case studies in various process industries.

H Seminars on industrial cogen- eration and heat pumps.

TechCommentaries and TechApplications are useful tools for electric utilities in help- ing their industrial customers to evaluate the technical and economic feasibility of specific electrotechnologies

Research reports on freeze concentration of dairy products, MW/vacuum drying of food, textile yarn drying, and heat pumps in evaporation/distillation applications.

Videos on waterjet cutting, freeze concentration, and dielectric drying.

EPRl’s interactive software programs are easy to learn and easy to use. They are available on floppy disks for IBM PC and compatible computers.

H Software such as APLUS, HPSCAN, IMlS (Industrial Market Information Service), and IPI (In- dustrial Program Index).

N Ongoing relationships with process industry trade associa- tions-such as the National Food Processors Association (NFPA), the Technical Association of Pulp and Paper Industries (TAPPI), and the National Petroleum Refiners Association (NPRA)-as well as with the National Food and Energy Council (NFEC), the Association of Energy Engineers, and the Department of Energy.