Industrial gases in the chemical industry

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Together with optimum supply of acomplete selection of gases, Linde provides the chemical industry withcomprehensive know-how andextensive supporting services:

E Process consulting, economic feasibility studies

E Advice on safety issues

E Process design calculations

E Experimental investigations

E Development of technological and engineering solutions

E Implementation and start-up

E Financing, rental and operation ofgas production and distributionfacilities.

Linde industrial gases –partners to the chemical industry

Industrial gases find vast and versatileapplication in the chemical industry.They serve as feed materials for syn-thesis processes, they ensure andimprove the economy of processesand plants, they enhance productquality and plant safety, and they helpto protect the environment.

Supply of gases must be matchedspecifically to the diversity of pro-ducts, processes and productioncapacities. Essential factors in thisare dependability, economy andwide-ranging applications solutions.

Quality, safety and environmentalprotection are key ingredients in all ofLinde’s work. Our integrated QSEmanagement system based on DINEN ISO 9001, DIN EN ISO 14001and SCC assures consistently highquality and safety of our productsand services as well as environmen-tal compatibility in the application of industrial gases and their disposalwhere required.

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Industrial gases – components for synthesis processes

Applications in general

In the chemical industry industrialgases are used principally

E as chemical reactants

E for assuring plant safety

E for protection of the environment

E in analytical chemistry

E for industrial service.

Oxygen, hydrogen, carbon monoxide,carbon dioxide and synthesis gas are reactants in a large number ofimportant synthesis processes. Theaccompanying charts summarizecommon reactions working with oxy-gen, hydrogen, carbon monoxide and carbon dioxide.

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Carbon dioxide Metal hydroxides

Hydrocarbons

Sodium phenolate

Urea

Salicylic acid

Carbonates,hydrocarbonates

Esters

Alkylene carbonates,polyalkylene carbonates

Ammonia

Alkylene oxides

Hydrogen

Ammonia

Methanol

Short-chain and desulphurizedpetroleum products

Hydrogenatedhydrocarbons

Aldehydes

Hydroxylammonium sulphate

Metals

Hydrogen peroxideAir (anthraquinone process)

Carbon monoxide,carbon dioxide

Hydrocarbons

Metal oxides

Nitrogen

Petroleum products

CO + olefins

NO + sulphuric acid

Methanol

Aldehydes, alcohols

Hydrogen

OlefineOlefins

Chlorine

Carbon monoxide

Metals

Hydrocarbons

Carboxylic acids

Phosgene

Metal carbonyls

Oxygen

Paraffins, olefins

Paraffins, olefins

Olefins

Olefins, aldehydes

Petroleum refining residues

Hydrogen sulphide Sulphur

Synthesis gas

Carboxylic acids

Epoxides

Alcohols

Aldehydes

Reactions with carbon monoxide

Reactions with oxygen

Reactions with carbon dioxide Reactions with hydrogen

4

30

25

20

15

10

5

020 22 24 26 28 30

Oxygen concentration in vol%

Cap

acit

y in

crea

se in

%

90% H2S 70% H2S 30% H2S50% H2S

Central supply pipeline

On-site oxygen plant

Tank

Air

Gas distributor

Air andoxygen toClaus plant

Claus plant processcontrol system

Controller

Measuringand

controlunit

Vaporizer

Oxygen

Oxygen for oil refineries

Oxygen is used at oil refineries for thepartial oxidation of petroleum resi-dues, to regenerate catalysts in FCCplants, and to improve the perfor-mance of Claus plants.

In the Claus process, hydrogen sulphide is converted to elementalsulphur. Removal of sulphur com-pounds is required in the processingof petroleum, natural gas and coalto motor fuels, synthesis gas and fuel gas.

Its purpose is to ensure compliancewith both the emission levels stipu-lated under environmental laws andthe maximum concentrations of sulphur compounds imposed bytechnological constraints.

At present, the oxygen content ofatmospheric air is primarily utilized forthe oxidation of hydrogen sulphide.

Adding oxygen to the air or usingpure oxygen results in a number ofbenefits:

E Increased plant capacity

E Higher oxidation temperatures

E Reduced load on off-gas treat-ment systems due to lower concentration of inert nitrogen

E New plants can be built smaller.

Gases for oil refineries – greater efficiency, cleaner environment

Claus plant

Capacity increasethrough oxygen enrichment

Schematic diagram of oxygen enrichment

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Left:Production of syn-thesis gas andmethanol from oilrefining residues

Linde hydrogen plant

Above:Gasification of oilresidues with oxygen

Hydrogen for oil refineries

An oil refinery is both a producer anda consumer of hydrogen, the volumesconsumed usually exceeding thoseinternally produced.

Hydrogen is needed as a reactant inhydrorefining and hydrocracking.Since refineries are shifting their out-put to larger quantities of low-sulphur,low-aromatics and brighter products,demand for hydrogen will continue to grow.

The main processes for productionof hydrogen are:

E Steam reforming of methane

E Gasification of oil refining residuesand recovery from synthesis gas

E Recovery from refinery off-gases.

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Oxidation of ammo-nia for production ofnitrogen monoxide

Product Feed Air Oxygen Enriched airAcetaldehyde Ethylene P P PBenzoic acid Toluene PCyclohexanone Cyclohexane P PAcetic acid Acetaldehyde P PEthylene oxide Ethylene PPropylene oxide Propylene P PNitrogen monoxide Ammonia PTerephthalic acid p-Xylene P PVinyl acetate Ethylene, acetic acid PVinyl chloride Ethylene, hydrogen chloride PHydrogen peroxide Hydrogen P P

Oxygen:Improving economy – reducinginvestment costs

Increasing use is being made of in-dustrial oxygen in oxidation processesfor the manufacture of oxides, alde-hydes, and also acids and alcohols.It can greatly improve the economyof existing plants and reduce capitalexpenditure for new plants. The meth-ods used are oxygen enrichment ofthe oxidizing air, adding oxygen to thefeed stream and substituting pureoxygen for air.

The benefits of oxygen are:

E Larger throughput in the samesize of plant by lowering the concentration of inert nitrogen

E Higher temperatures in the reacting stream

E Accelerated reactions due tohigher oxygen concentration

E Higher selectivity of the oxidationprocess in parts

E Smaller off-gas flows

E Lower energy consumption.

Oxidation processes using oxygen

Economical reactants for production ofbasic chemicals and intermediates

Hydrogenationof phenol tocyclohexanone

Production ofepoxy resinsusing carbondioxide

Carbon dioxide:reactant, solvent, pH control agent

Carbon dioxide is used, for example,in the manufacture of urea, salicylicacid, carbonates and polyalkylenecarbonates, and in several other or-ganic chemistry synthesis processes.

Supercritical carbon dioxide is aprospective replacement for environ-mentally hazardous solvents as currently required in a number ofchemical synthesis reactions and is capable of improving the propertiesof some products made by poly-merization.

Beyond that, carbon dioxide is widelyused for pH-value control and neu-tralization of liquids.

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LiquidSolid

103

102

10

1

10-1

173 223 273 323 373

Pre

ssur

e, p

, in

bar

Temperature, T, in K

p, T diagram

Criticalpoint

Triple point

Gaseous

Supercritical

Hydrogen:Basic chemicals, hydrogenation,catalyst production

Hydrogen is a reactant in the manu-facture of basic chemicals and intermediates as well as specialtychemicals and pharmaceuticals.Synthesis gas, a mixture of hydrogenand carbon monoxide, is employedabove all for synthesis of methanol andin the hydroformylation of olefins toaldehydes and alcohols. Ammonia ismanufactured from a different syn-thesis gas mixture of hydrogen andnitrogen.

Another process of considerable im-portance is hydrogenation, whichinvolves the homogeneous or heterogeneous catalytic addition of hydrogen to organic compounds.

Examples are:

E Hydrogenation of adipic acid dinitrile to hexamethylene diamine

E Hydrogenation of benzene to cyclohexane

E Hydrogenation of phenol to cyclohexanone.

Industrial hydrogen is also used inthe manufacture of catalysts forreducing metal oxides to the activemetallic form and to regulate chainlength in the polymerization of pro-pylene to polypropylene and in themanufacture of polyethylene.

Phase diagram for CO2

Neutralization of alkaline effluents with carbon dioxide(SOLVOCARB® process)

Before alkaline effluents from an in-dustrial plant can be discharged to the municipal sewage system,they must be neutralized.

Carbon dioxide has several advan-tages over mineral acids in neutralizingalkalies. To begin with, it is not classi-fied as a material which is hazardousto water. Moreover, it is not associatedwith high salt loads, which may bepenalized by special charges, and theflat neutralization curve excludes risk of over-acidification.

Neutralization of wastewater withcarbon dioxide is carried out with theLinde SOLVOCARB® process.

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Neutralization with a SOLVOCARB®

reactor in a chemical plant

Oxygenation of wastewater using theSOLVOX®-B process

Environmental protection and resource recovery – reliable, efficient, economical

Oxygen for wastewater treatment(SOLVOX® process)

Many problems occurring in thetreatment of wastewater are due toa deficit of oxygen. In the chemicalindustry especially, where effluentsare usually heavily contaminated, thiscan cause considerable trouble suchas degraded treatment performanceor appreciable odor nuisance due toanaerobic decomposition processes.

Industrial oxygen is often capable ofremedying such situations.

The necessary oxygen is injected intothe wastewater by the Linde SOLVOX®

process. Particular advantages ofthis process are its low investmentcosts and flexible adjustment of oxy-genation to actual needs.

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ClinkerSpent sulphuric acid,solvent

Primary air + O2

Planetary cooler(secondary air)

Gypsum,fly ash (Al, Si, Fe),coal

Exhaust gas

Processing spentsulphuric acid inrotary kiln

Cleaning acetone-contaminated waste gasby cryocondensationwith liquid nitrogen

Raw gas, 0ºC40 g/m 3 of acetone

Clean gas, approx. –20ºC< 0.15 g/m 3 acetone

Primary condensercooled by clean gas

Cryocondenser cooledby liquid nitrogen

Nitrogen gas

Liquidnitrogen

Condensed acetone

Raw gas, –60ºC< 5 g/m3 of acetone

Condensedacetone

Clean gas, < –95ºC< 0.15 g/m3 of acetone

Recovery of valuable organic ma-terials and waste air purificationby cryocondensation

Cryocondensation works with liquidnitrogen as a low-temperature refrigerant. The polluted air stream iscooled in heat exchangers to belowdewpoint temperature, causing con-taminants or recoverable materialspresent in vapor form to condense.Liquid nitrogen achieves condensingtemperatures well below thoseattainable with conventional refriger-ating machines.

Benefits

E Convenient adjustment of processtemperature to changed conditions

E Regulation of condensation performance over a broad range

E Treatment of highly contaminated waste air streams

E Reduction of residual contaminantlevels to parts per million.

Oxygen in processing of spentsulphuric acid

Mineral wastes and spent sulphuricacid can be processed in rotary kilns.For example, gypsum is processed inthese rotary kilns jointly with spentsulphuric acid and coke, followed byconversion of sulphur dioxide tosulphuric acid.

Enriching the air supplied to the kilnwith oxygen achieves the followingbenefits:

E Increased processing capacity

E Combustion of solventscontaining higher levels of water.

Flowsheet for cryocondensation

Rotary kiln supplied with oxygen-enriched air

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Nitrogen

Heat exchanger

Inert gas grid

Pump

Coolantreturn

Coolantsupply

Reactor

Reactors cooled withliquid nitrogen

Inerting in storage ofchemical products

Inerting in chemical processes

Lowering oxygen concentrations to a safe level by inert gases (nitrogenand carbon dioxide) is a provenmethod of preventing oxidation, firesand explosions.

A cushion of inert gas is frequentlyplaced over liquids in storage tanks.Silos are purged with inert gas as aprecaution against dust explosions.

Another important application is forexplosion protection on reactors inwhich oxidation takes place in the liquid phase. Due to the risk of anexplosive mixture forming in the headof the reactor, it must be purged continuously with inert gas so as todilute the gas mixture below its ex-plosion limit.

Cooling vessels and reactors

Control of temperature is oftenvital to achieving high yield and goodquality of chemical compounds manufactured by synthesis. Liquidnitrogen enables low-temperaturesynthesis of chemical and pharma-ceutical products to be carried outconveniently at -80 °C or such othertemperature as may be required.

Cooling can be performed by threemethods:

E Injecting liquid nitrogen directlyinto the reactor.

E Cooling the reactor contents bynitrogen flow through an externaljacket or an internal cooling coil.

E Indirect cooling by a secondarycircuit.

The benefits of liquid nitrogen coolingare:

E Cooling capacity variable over awide range

E Low investment and operatingcosts

E Absence of environmentally damaging refrigerants or noisenuisance .

Safe inerting and efficient cooling

Reactor cooling by secondary circuit

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Catalytic reactor fordeoxygenation ofboiler feedwater

SOLVOGEN®

control panel

Laboratory in the chemical industry

Gas and equipment supply forlaboratories and pilot plants

Ultra-pure gases, gas mixtures andcalibration gases are required by laboratories and pilot plants in thechemical industry for analytical and measuring applications and testoperation.

Linde has a stock range of standardgas mixtures.

Calibration gases – precision gasmixtures of customer-specified composition and certified analysis foruse in calibrating measuring andanalytical instruments – are suppliedin pressure cylinders.

Gases of high-grade quality areessential for reliable and accurateoperation of gas analyzers. Lindesupplies operating gases for gaschromatography, flame photometry,chemiluminescence, spark spec-troscopy, ECD analysis and atomicabsorption, and filling gases forcounter tubes.

Linde designs and builds completegas supply systems for laboratoriesand pilot plants as either standard or customized units.

Deoxygenation of boiler feedwater (SOLVOGEN® process)

Because it corrodes piping and ves-sels, oxygen must be removed fromboiler feedwater, hot water systemrecirculating flows and chemicalprocess water. The SOLVOGEN®

process has been designed for thispurpose.

The process is based on convertingdissolved oxygen with hydrogen overa palladium catalyst at ambient temperature.

Linde supplies SOLVOGEN® systemsto treat water flows as small as 10 m3/h in the food industry or aslarge as 1000 m3/h in power stations.

Other gas applications for the chemical industry

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Pig trap and nitrogen feedingpoint in Rongellen,Switzerland

All of the comprehensive services andservice processes available fromLinde are designed to minimize thetime required for inspection andmaintenance of complete systems,equipment and components.

They also satisfy increasingly stringentenvironmental demands. All gasesemployed are non-flammable, non-toxic and non-corrosive. Moreoverthey reduce fire and explosion risks,permitting safe start-up of equipment.

Services available are:

Piping and pipeline cleaning bythe Sandjet® process

This is a blast cleaning method usingnitrogen to force the abrasive throughthe piping system. The abrasive isrecovered for re-use.

Leak testing

A nitrogen-helium gas mixture is usedfor leak testing of complete systemsor individual components at operatingpressure.

System drying

Drying of pipings, complete produc-tion systems or individual componentsis carried out with nitrogen, whichmay be heated to relatively high tem-peratures as required.

Reactor cooling

Rapid cooling of reactors is achievedby controlled injection of liquid nitrogento prepare them for servicing. Timesaved for cooling greatly reduces theduration of system shutdown.

Service processes – quicker inspections, reduced fire risk,environmentally compatible

Leak test on pipingassembly for hydrogen plant

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Cleaning moldsused in productionof polyurethanefoam

Agitator used inpaint manufactureprior to beingcleaned

Agitator after being cleaned bythe CRYOCLEAN®

process

Pigging and pipeline renewal

A pig is a mechanical device forcedthrough a pipeline system by intro-ducing nitrogen at high pressure, displacing the oil or other fluid into a receiving tank and cleaning thepipe. At the same time the pipeline isinertized by the nitrogen. Cleaningcan be combined with remote visualinspection by video camera.

Mobile natural gas supply

Long-distance or regional gas pipe-lines have to be taken out of servicewhen modernization, rerouting orrepairs become necessary. For thechemical industry this may normallynecessitate temporary shutdown ofproduction facilities. During suchtimes, continuous supply of gas can

be maintained with Linde mobile nat-ural gas stations, self-contained unitsoperating at a high level of safety andreliability.

Blast cleaning with dry ice

In the CRYOCLEAN® process, dry icepellets frozen to -78 °C are propelledat high velocity onto the surfaces ofwork to be cleaned. On impact, thedry ice immediately vaporizes, remov-ing dirt and impurities while leavingthe cleaned surface clear of grit orsludge residue. Typical applications in the chemical industry are for clean-ing heat exchangers, piping and agitators.

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Tanker delivering liquid hydrogen

Gas cylinders in various sizes

With our tightly knit production, salesand distribution network we canguarantee fast, reliable and econom-ical supply of gases to users by facilities ranging from two-litre steelcylinders to on-site units, from 75,000-litre liquid tanks to directpipelines.

Gas cylinders

Upwards of four million gas cylindersdisplaying the Linde name are in circulation in Europe. They are deliv-ered to users by road truck or trailer,depending on the quantities required.To enable customers to maintain arunning inventory of gases, Linde pro-vides the LIBAS® cylinder trackingsystem, which continuously monitorsmovement of all cylinders.

Liquefied gas tanks

Customers whose requirements exceed the capacity of cylinder deliv-eries are supplied with liquefied gases transported by tanker truck andstored for use in tanks installed ontheir premises.

Linde furnishes vaporizers and allother associated equipment togetherwith the storage tanks and assumesresponsibility for the entire installation,maintenance and inspection work.Electronic remote monitoring of tanklevel ensures that an adequate supply of gases is available at all times.

ECOVAR® on-site units

Above a certain consumption rate,supply of gases by road tanker is not a satisfactorily economical prop-osition. In such instances we recommend installation of a plant for on-site production.

Gas supply –complete and functional

ECOVAR®-M plant

ECOVAR®-A plant

ECOVAR®-C plant

Merseburg

Buna

Halle

Dessau

Bitterfeld

Leipzig

Leuna

Rodleben

HydrogenNitrogenOxygen

Plesteritz

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Pipeline supply is particularly eco-nomical in industrial regions whereseveral users are linked to a supplygrid served by a central productionfacility.

Linde is well positioned for pipelinebusiness. Through its Process Engi-neering and Contracting Division thecompany has access to an extensiverange of equipment. Air separationplants are designed and built for pipe-line supply of oxygen and nitrogen as well as plants for production ofhydrogen, carbon monoxide andsynthesis gas.

The ECOVAR® supply concept combines an on-site production unitand liquid storage tank for supply of nitrogen or oxygen. Basic demandis covered by the capacity of the production unit with a reserve supplyavailable in the storage tank to meetpeak consumption and emergencysituations. Customers can chooseamong three alternatives accordingto the required product, purity andproduction capacity: ECOVAR®-C(cryogenic process), ECOVAR®-A(adsorption process) or ECOVAR®-M(membrane process). All three typesare marked by high reliability of supply,economical production cost and ahigh level of flexibility.

Pipeline grid

Direct delivery by pipeline from one of our production centers is the mosteconomical form of supply for com-panies using large tonnages of gases. A growing number of high-volumeusers have endorsed this option byreason of its obvious advantages.Linde puts up the capital for newplants, invests its many years of experience acquired in operation ofnumerous comparable facilities, and moreover guarantees reliablesupply in times of peak demand or emergencies through its backupresources of large tank farms andextensive distribution capabilities.

Steam reformer producinghydrogen in Milazzo, Sicily

Linde pipeline sys-tem in Germanytotalling more than400 kilometres supplies hydrogen,nitrogen, carbonmonoxide and oxy-gen to high-tonnageusers

Performance on site –Linde Industrial Gases

Linde AGWerksgruppe Technische GaseExport Head OfficeSeitnerstraße 7082049 Höllriegelskreuth/GermanyPhone: + 49/89/74 46-0 Fax: + 49/89/74 46-12 30http://www.linde.com/linde-gas

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Linde industrial gases are encountered inapplications as varied as welding, freezing,propulsion, heating, industrial cleaning, res-piration or testing. They improve the quality of life and they help to secure thefuture by making production operations more efficient and economical.

Supply of the gases themselves is supportedby expert counselling and know-how, custom-ised hardware, custom-application testing,and the complete handling associated withindustrial gases.

Gases can be supplied in any form appropri-ate to customers’ requirements: in cylindersor multi-cylinder batteries, from liquefied gastanks, through ECOVAR® on-site productionunits, by pipeline.

Industrial cleaning

MetalworkingFood industry

Fuel and power

Applications and supplyequipment

On-site servicing

Qualified and comprehensive advice

Metallurgical and chemical industries

Microelectronics

Environmental engineering

Pipelines

ECOVAR®

on-site production

units

Air separation plants

Gas cylinders

Site tanks

Medicine

Glass industry

Know-how

Supply

Counselling

Production

Service

Applications

Your local supply center: