Perfect on-site supplyIntelligent concepts for on-sitegas production

Contents:

3         Industrial gases

4|5      Purity and quantity as required

6|7      Cryogenic air separation

8|9      Non-cryogenic air separation

10       Hydrogen production

11       Step by step to an on-site supply

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There is a virtually unlimited supply of nitrogen,oxygen and argon because of their natural occur-rence within the atmosphere. These gases,along with the rare noble gases present in air,can be obtained through special separationprocesses. Any components from this separationprocess that are not required are simply returnedto the atmosphere.

Every gas has its special “qualities”:Today, air gases and hydrogen are as natural arequirement for industrial processes as waterand electricity. Oxygen, for example, is used insteel refining, and is also essential in the glassindustry as well as in environmental technology.The properties of nitrogen are used for inerting inchemical, petrochemical and pharmaceutical pro-cesses, among others. Argon, a noble gas ob-tained from air, plays a central role in the produc-tion of stainless steel and is also used as a purgegas in semiconductor manufacture.

Hydrogen is used in annealing high-alloy steelsand sintered parts as well as oxide reduction ofmolten metal. It is also used as an efficient fuelin glass polishing.

Industrial gases:as important as water and electricity

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Purity and quantity as required

On-site gas production facilities make sensewherever there is a constantly high demand forindustrial gases. An on-site unit facilitates a cost-optimised and reliable supply, which is madeeven more secure through the use of backupsystems and Messer logistics.

The volume and purity required varies fromsector to sector and also depends on the processapplications that are used. Messer thereforeoffers its customers a supply concept that isprecisely tailored to individual requirements.

There are basically two air separation methods:cryogenic and non-cryogenic.

Cryogenic air separationIn cryogenic air separation units, the gasespresent in the air are separated according to thelow-temperature rectification principle, makinguse of the gases’ differing boiling temperatures.In addition to the two main components, nitrogenand oxygen, it is possible to obtain pure formargon as well as the rare noble gases krypton  and xenon.

The cryogenic separation principle is used inthe following types of units:• Multi-product high capacity air separation units    with optional liquefaction• CryoGAN nitrogen generators• CryoGOX oxygen generators

ConstituentChemicalsymbol % by volume

Nitrogen N2 78.08

Oxygen O2 20.95

Argon Ar 0.93

Carbondioxide CO2 0.035

Hydrogen H2 5 · 10-3

Neon Ne 1.82 · 10-3

Helium He 5.2 · 10-4

Krypton Kr 1.14 · 10-4

Xenon Xe 8.7 · 10-6

Air separation unit at Messer in Hungary

The composition of air

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Non-cryogenic air separationNon-cryogenic air separation processes work onthe pressure swing adsorption principle or arebased on separation by means of semiperme-able membranes.The following types of units arewell established:

• Pressure swing adsorption (PSA)• Vacuum pressure swing adsorption (VPSA)• Membrane units    

Messer offers air separation units, based oncryogenic and non-cryogenic separationprocesses, with the following nominalcapacities:

Nominal capacity

Type of unit Product Nm³/h t/day

Air separator O2 750 - 60,000+ 25 - 2,000+

N2, Ar up to 180,000

Generators O2 2,500 - 12,000 85 - 410

N2 200 - 5,000 6 - 150

PSA N2 10 - 5,000 0.3 - 150

PSA/VPSA O2 100 - 5,000 3.4 - 170

Membrane N2 10 - 3,500 0.3 - 105

Which type of unit is “best"?It is necessary though to determine requirementsin terms of gas purity, gas quantity and demandprofile. An initial selection as to the appropriatetype of unit can be made on the basis of the twodiagrams below.

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PSA unit for the production of nitrogen

99.6 %

Purity

93 %

90 %1                      10                    100              1,000               10,000                                                               Nm3/h

1                       10                   100                     1,000             10,000                                                             Nm3/h

99.999 %

99,9 %

Purity

90 %

cylinders andliquid gas supply

Cylinders andliquid gassupply

Oxygen supply

Nitrogen supply

Cryogenic airseparation units

Cryogenic airseparation units

PSA/VPSA units

PSA/Membraneunits

Cryogenic air separation unitsensure a flexible and reliable supply

Air separatorsFor industries that either consume large quanti-ties of industrial gases (steel, petrochemicals,refining) or require a multi-product supply (oxy-gen, nitrogen and argon), the gases are usuallysupplied via an air separation unit (ASU).

With this type of unit, air is first compressed toaround 6 bar. After the removal of unwantedcomponents – mainly carbon dioxide andhumidity – in a molecular sieve, the air is passedinto heat exchangers where it is cooled until itliquefies. This is followed by rectificatoryseparation into the individual components, whichare then evaporated in a countercurrent to theincoming flows and reheated to near-ambienttemperature.A further option is the production of liquidproducts by means of additional cooling usingexpansion turbines.

Technology that meets your requirementsMesser offers a reliable and varied range ofcryogenic air separation units, providingmaximum flexibility from 25 to more than 2,000metric tonnes per day (in terms of oxygencapacity).

Flow diagram of an air separation unit

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Compressor

GaseousOxygen

GaseousNitrogen

Regeneration GasHeater (electric or

steam heated)

MolecularSieve Adsorber

Air

Main Heat Exchanger

Regeneration Gas Vent

TurbineLP

Column

CrudeArgon-Column

HPColumn

Argon

LiquidNitrogen

LiquidOxygen

Subcooler

Even our so-called standard packages possessall the advantages from our technical experiencein innovative plant design combined with shortdelivery times and low costs. Where an individu-ally designed plant is the right solution, ourteam of experts will ensure that every customerrequirement relating to product specifications,pressure, flow rate or flexibility is fulfilled to thehighest possible standard.

Messer is also the right partner for high puritygas facilities. Our HIGH PURITY air separationunits have flexible capacity at purity levels of99.995% for oxygen and in the ppb range fornitrogen and argon.

Also available are liquefiers for a 100% liquidsupply, which Messer builds with capacities ofup to 600 metric tonnes a day.

CryoGAN nitrogen generators – a particularlycost-effective solutionNitrogen (N2) is known for its protective qualities,which is why it is often used in inerting andshielding applications where an oxygen-freeatmosphere is required. Medium-sized consum-ers often use N2 as a “utility gas”, which issupplied in liquid form. The focus is on aparticularly cost-effective supply.

In order to meet the demand for larger quantitiesof nitrogen at low costs, Messer has developedthe CryoGAN generator. This is a special nitrogenproduction unit that operates on the principle ofcryogenic air separation.

Messer develops and builds the CryoGANgenerators in-house. The units are modular indesign and offer a graduated capacity range from200 Nm3/h to 5,000 Nm3/h.

CryoGOX oxygen generators – compressedair and compressed costsWith CryoGOX oxygen generators, Messer hasdeveloped a cost-effective, reliable, flexible anduncomplicated oxygen supply. They are in de-mand from a variety of industries (pulp andpaper, glass, ceramics, chemicals andmetallurgy).

These generators, too, are based on the principleof cryogenic air separation, albeit with internalproduct compression: the liquid oxygen isextracted from the low pressure column andpumped through the heat exchangers underpressure in order to cool the incoming air gases.The resulting stream of gaseous oxygen isavailable to customers at pressures of up to 20bar. The main advantages of this concept are thenon-requirement of an expensive oxygencompressor, high oxygen purity (99.6%) and thecapability of cost-effective liquid nitrogenproduction for stockpiling.

CryoGOX oxygen generators are built by Messeraccording to customer specifications. Capacitiesfrom 85 to 400 metric tonnes a day cover mostindustrial applications.

How the customer benefits from cryogenicair separation 

• High oxygen purity

• Very reliable operation

• Low energy consumption

• Parallel production of liquid oxygen and   liquid nitrogen

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Non-cryogenic air separation unitsfor practically every requirement

Messer offers a portfolio of non-cryogenictechnologies for every conceivable applicationand customer process.

PSA units – air is all you needThe PSA (Pressure Swing Adsorption) process isbased on the physical adsorption properties ofspecially treated molecular sieves. PSA units onlyneed clean, dry air in order to generate N2 or O2

cost-effectively and with purities of up to 99.9%(nitrogen) and 93% (oxygen). This air is com-pressed up to 10 bar, purified and then passedthrough vessels filled with the molecular sieve,either carbon molecular sieves (CMS) or zeolites,depending on the type of gas required (O2 or N2).

A continuous nitrogen or oxygen supplyis achieved by switching the gas stream: whileone vessel is in operation, the other isregenerated by reducing the pressure. Theunwanted gas components are released into theatmosphere.

VPSA units – oxygen production can be thiscost-effectiveThe VPSA (Vacuum Pressure Swing Adsorption)process represents a modification of the PSAprocess. VPSA units have a fan which generatesan overpressure of around 1.5 bar, and a vacuumpump, which is used during the regenerationcycle. This leads to a reduction in energyconsumption.

Membrane unit

Membrane units – nitrogen at the touch of abuttonThe membrane process makes use of thedifferent rates at which air gases diffuse througha polymer membrane. Atmospheric air is filtered,compressed to the required pressure, dried andthen passed through a membrane module. Theair components with the higher rate of diffusion(O2 and CO2) penetrate the polymer membranefibres more quickly, resulting in a nitrogen-richflow as the primary product. The purity of the N2

gas flow depends on the flow rate through themembrane module, reaching 93.0 – 99.5% andmore if operated efficiently.

Backup system

Reliable backup supplyA secure supply from a backup source – just in caseit is ever needed – is the icing on the cake of any on-site concept, allowing the consumer to sleep easywith regard to the gas supply, even when there aremaintenance downtimes, power cuts or otherunforeseeable events. Our regional logistics networkwith centrally managed Europe-wide coordination,combined with sophisticated production planning,ensures that every single customer receives areliable supply of technical gases from Messer, evenduring planned and unplanned downtimes.

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Flow diagram for a nitrogen membrane unit

Flow diagram for a PSA unit

How the customer benefits from non-cryogenic air separation

• Low costs – thanks to low energy    consumption• Reliability – selected components from   well-known manufacturers and regular   maintenance are essential for reliable   plant operations• Nitrogen/oxygen as required –   quick start-up and uncomplicated    operation enable the customer to use    gas as an operational utility• Modular units – transportable and     low space requirement• Safety – through low operating    temperatures

Shared advantages: flexibility andeconomyAll the non-cryogenic processespresented here – PSA, VPSA andMembrane – are very flexible in terms oftheir application. In addition, they offergreat potential in terms of economy,which is maximised through the adviceand support provided by the Messerspecialists, based on the stipulated purityand the required throughput.

Air compressor Air buffer

Cold dryer

Flow meter

Filtration unit Pressure regulator

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Processstoragetank check valve

Nitrogen to customer

Orifice

Carbonmolecularsieve

Air compressor

Cold dryer

Air buffer Filtration unit

Heating

Nitrogen buffer(optional)

Flow meter Productvalve

Nitrogen to customer

Modules 1 - nAtmosphere

Oxygencontrolvalve

Flue gas valve

Atmosphere

Air inlet valve

CMSCMS

Analysis

Hydrogen production –as individual as its users

Messer offers a whole range of technologies forthe production of hydrogen and Syngas, with thechoice of the optimum process depending onseveral factors. These include the application,volume requirement and purity. The experts fromMesser will be happy to advise you on this.

Electrolysis, steam reformer or PSA –a question of the starting pointFor smaller hydrogen consumers or customerswho do not have an alternative source materialon site, Messer offers electrolysis units forhydrogen production with a capacity of 0.5 to 100 Nm3/h. These units, individually designed byMesser, are modular in design, offeringmaximum flexibility when it comes to planning orexpansion. Hydrogen purities of 99.9% andabove can be achieved, thereby satisfying eventhe high purity standards of the food, electronicsand chemical industries.

Steam reformers use natural gas as a feedstockand can be used for both small and largehydrogen units. With the so-called steamreforming process, the feedstock is mixed withprocess steam, heated to approximately 480°Cand then split in the reformer using a nickel-based catalyst. In the CO Shift Reactor, in whichcarbon monoxide (CO) reacts with H2O to formH2 and CO2 (catalytic conversion), the hydrogencontent in the reformed gas increases further.

Hydrogen unit, 2,000 Nm3/h

After this, the hydrogen-rich gas is cooled inseveral stages and condensate is separated.Finally, the hydrogen is purified in a multi-bedPSA unit. It leaves the PSA unit under 15 to 30bar of pressure and with a purity of up to99.9995%.

For companies that already have a hydrogensupply but require higher purities fordownstream use, Messer can supply hydrogenPSA units as separate units. They receive thehydrogen-rich gas flow and convert it into highpurity hydrogen (>99.999%).

The hydrogen PSA unit can be integrated intothe customer’s existing setup and operates fullyautomatically, with the number of adsorptionbeds (tanks) depending on the H2 throughput.The hydrogen product is available with constantflow, pressure and temperature values.

Hydrogen production through steam reforming

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Process Steam Steam Drum

Boiler

Boiler Feed Water

Cooler HydrogenCompressor

Pressure swingadsorption

Natural Gas

Flue Gas Steam Reformer

Export Steam

Fuel Gas

Hydrogen

Desul-furizer CO

ShiftReactor

Step by stepto an on-site supply

Technical gas supply requirements essentiallydepend on the industry and applications inquestion. Against this background, Messer hasdeveloped a “priority ranking list” to facilitateproject planning for an on-site supply in order tobe able to offer supply concepts that preciselymeet each customer’s requirements in terms ofgas type, quantity and quality:

1. The customer’s technology process

2. Process parameters, including type of gas,    pressure, purity, degree of automation,     operating times, consumption profiles

3. Initial assessment/feasibility of project in terms     of gas production technology,    energy consumption, gas costs, backup       facilities, safety considerations

4. Computer-based process modelling for     simulation of technical concepts

5. Reliability analysis, ensuring efficient,     uninterrupted operating times

6. Preparation and submission of tender for the     supply concept

7. Completion/acceptance of supply concept

8. Installation and start-up of unit

Our aim is to develop a supply concepttailored to your individual needsMesser’s aim in the area of on-site supply isclearly defined: on or next to the customer’s site,we operate units that are optimised to meet theparticular gas requirements of each customer.This means that the customer can use therequired gases just as easily as electricity fromthe grid. Such a supply is based on an appropriatesupply contract for technical gases. Alternatively,the customer can acquire an on-site unit andoperate it on his own. It is also possible to signan operational management contract withMesser. The sale of the units is handled throughCryogenic Engineering, a company that was setup as a joint venture between the Germancompany, Messer Group GmbH, and the Chinesemanufacturer of air separation units, HangzhouHangyang Co. Ltd.

Operating conditions and safety monitored atall timesWhile large air separators are manned by theirown operating teams, a fully automated,unmanned solution is often feasible for smallerunits. Messer has set up the European ControlCenter (ECC) in Budapest for the purpose ofoperating and monitoring such units. It isconnected with every single unit via a datatransmission system, facilitating round-the-clockmonitoring of the most important operating dataand any alert notifications. In the event ofabnormal operation of one of the units, the ECCarranges for Messer staff to resolve the problemon-site within a very short time.

PSA unit for hydrogen production                       All the units are remotely monitored from the

Control Center in Budapest.

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Messer Group GmbH is one of the leadingindustrial gases companies in Europe and China.The company operates air separation units forbulk production and for supplying large industrialconsumers from the steel, chemical andpetrochemical industries. Liquid oxygen, nitrogenand argon are some of the products in greatestdemand.

Messer has over 100 years of experience in thedesign and operation of air separation units and isconstantly strengthening its lead in expertise.The units that are built and operated by Messerare regarded worldwide as state-of-the-art interms of design, build quality and reliability.

Messer Group GmbHGahlingspfad 31

47803 KrefeldTel. +49 2151 7811-0

Fax +49 2151 7811-501info@messergroup.com

www.messergroup.com

Messer is active in 30 countries in Europe andAsia, as well as Peru, with more than 60operating companies. Its international activitiesare managed from Frankfurt am Main, with thecore technical functions – logistics, engineering,production and technology management –managed from Krefeld.

A strong background