With oxygen thechemistry is rightOxygen optimises the productionof sulphur and sulphuric acid

Production of sulphur – indispensable formany sectorsToday, sulphur is primarily used in the che-mical and pharmaceutical industries, but it isalso used in steel alloying. Sulphur also formsthe basis for the production of sulphuric acid,dyes, insecticides and fertilisers.

Elemental sulphur is almost exclusively producedfrom oil and natural gas using synthetic pro-cesses. The most important process from atechnical point of view is the CLAUS process.The first step involves splitting the sulphurcompounds contained in the oil to form hydrogensulphide (H2S) and hydrocarbons in a processcalled hydrocracking. The “sour gas” that isseparated by amine scrubbing is subsequentlyconveyed to the CLAUS process. In the CLAUSprocess, part of the H2S gas is converted intosulphur dioxide (SO2). This usually involves theuse of atmospheric oxygen. H2S is subsequentlyconverted into sulphur.

Meeting new requirements with existingplantsMany plants have reached their capacity limit inrecent years because of much stricter SO2

emission limits and the simultaneously risingsulphur content in the crude oil being used. Theconsequence of this is costly investment in newplant and equipment – or the intelligent use ofoxygen from Messer.

Oxygen optimises production and recycling

Messer and a partner company have developeda process whereby oxygen is supplied to the post-combustion zone of the CLAUS combustionchambers.

The capacity of CLAUS plants that have beenmodified in this way is increased by up to 60%.The process also boasts impressive costadvantages, with the modifications to existingplants only costing about one per cent of theinvestment costs associated with a new CLAUSplant. Another advantage is the completeconversion of ammonia and high-molecularhydrocarbons due to the increased combustiontemperature (> 1350 °C). This is a big plus for theenvironment.

Your sulphur production advantages at aglance:

Marked increase in CLAUS plant capacity•Easy upgrading of existing plants•No costly investment in new machinery andequipment

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Reduced environmental impact•

CLAUS combustion chamber Photo: Black & Veatch

Photo: DumagCLAUS combustion chamber in operation

CLAUS plant

Production and recycling of sulphuric acid –targeted optimisationWith annual global production of approximately200 million metric tons, sulphuric acid is the mostimportant inorganic base chemical. Sulphuric acidis mainly produced by burning sulphur in air. Inthis process, the SO2 that is produced duringcombustion is converted into SO3 using vana-dium pentoxide (V2O5) catalysts, and the sul-phuric acid is produced in the double-contactprocess through 2-fold absorption of the SO3-containing gas. Since the price and sales ofsulphuric acid are subject to strong fluctuations,there is a growing desire for flexible methods ofincreasing the capacity of existing facilities.

Here, too, the use of industrial oxygen by Messeris an attractive alternative to cost-intensive plantexpansions. This involves adjusting the com-bustion process to facilitate a higher SO2 con-centration. Through targeted injection, sufficientoxygen is supplied to ensure completeconversion into SO3. 

Schematic representation of the supply of secondary oxygen to CLAUS combustion chambers

The double-contact process is the most important industrial-scale method of producing sulphuric acid.

Photo: Outotec

Claus gasFuel gas

Burner Combustion chamber

Oxygen

Inert gas

Air

Pilot burner

Waste sulphuric acid – clean with oxygenRecycling waste sulphuric acid is an importantcontribution in terms of environmental impactreduction. Waste acids with a high concentrationof non-volatile organic contaminants can only berecycled by thermal cracking. The costs oftreatment depend on the process gas flow rateand its sulphur dioxide concentration.

It is possible to increase the efficiency of thisprocess significantly with oxygen and know-howfrom Messer. By using oxygen as an oxidisingagent, the nitrogen ballast in the air is replaced byprocess gas containing sulphur dioxide, resultingin a significant increase in sulphuric acidproduction and an equally significant drop inoperating and energy costs.

Working together with operators of wastesulphuric acid cracking plants, Messer hasdeveloped safe and reliable methods of injectingoxygen into the various cracking reactors underproduction conditions. Oxygen can be used toincrease the efficiency of any waste sulphuricacid recycling process that involves the use ofthermal reactors (Grillo process, Lurgi/Staufferprocess, fluidised bed reactors).

Your sulphuric acid production and recyclingadvantages at a glance:

Increase in efficiency (de-bottlenecking) ofexisting plants

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Smaller design of new plants•Smaller waste heat recovery units and flue gasconditioning systems

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Increased yields and turnover•Lower energy costs•Improved product quality•

Are you thinking of optimising your existing plantand are considering the use of industrial gases?

We will be happy to help you implement yourideas. Please do not hesitate to contact us:

Dr. Walter Bachleitner,Senior Specialist Chemistry & EnvironmentE-Mail: walter.bachleitner@messergroup.com

Joachim RohovecSenior Manager Application TechnologyChemistry/EnvironmentE-Mail: joachim.rohovec@messergroup.com You can also download this brochure andmany others in PDF format from our website:www.messergroup.com

A targeted O2 supply increases theefficiency of cracking units.

Sulphur in powder formPhoto: Dumag

Oxygen mixer for combustion air enrichment

O2

AirMesser Group GmbH

Gahlingspfad 3147803 Krefeld

walter.bachleitner@messergroup.comwww.messergroup.com