The Boc Group, Inc.

Alan G Stokley

Ramachandran Krish Krishnamurthy

Steven L Lerner

Virginia A Malik

Yagya Shukla

A process for separation of a gas mixture containing three components, e.g. a mixture comprising hydrogen, carbon monoxide and carbon dioxide produced by steam reforming a hydrocarbon, by pressure swing adsorption is disclosed. In one embodiment of the process, the gas mixture is sequentially passed through first and second adsorptive regions each of which adsorbs a second component more strongly than a first component but less strongly than a third component, a first fraction enriched in the first component is withdrawn from the downstream end of the second region, introduction of gas mixture to the first region is stopped and the second region is closed to the first region, a second fraction enriched in the second component is withdrawn first from the upstream end of the second adsorptive region while passing gas mixture enriched in the third component into the first region from its upstream end and then from the downstream end of the first region, and withdrawing a third fraction enriched in the third component from the upstream end of the first region. The separation process is also applicable to other gas mixtures such as a mixture of hydrogen, argon, methane and nitrogen commonly available as ammonia plant purge gas from which ammonia has been removed.

Separation of gas mixtures including hydrogen

Highly purified gaseous hydrogen and liquid carbon dioxide are produced from a steam reformer/shift converter by passing the effluent from the latter through a multibed hydrogen PSA unit followed by an uncoupled carbon dioxide PSA unit. The carbon dioxide PSA unit produces a hydrogen-rich stream which is recycled to the feed to the steam reformer, a carbon dioxide-rich recycle stream which is recycled to the carbon dioxide PSA unit feed and a carbon dioxide-rich product stream which is introduced under pressure to a liquifier. A waste stream from the liquifier is recycled to the carbon dioxide PSA unit feed. A portion of the carbon dioxide-rich product stream is withdrawn from the compressor at a stage such that its pressure is higher than that of the carbon dioxide PSA unit and returned thereto as a cocurrent purge preceding bed regeneration to obtain product.

Hydrogen and carbon dioxide coproduction apparatus

Highly purified gaseous hydrogen and liquid carbon dioxide are produced from a steam reformer/shift converter by passing the effluent from the latter through a multibed hydrogen PSA unit followed by an uncoupled carbon dioxide PSA unit. The carbon dioxide PSA unit produces a hydrogen-rich stream which is recycled to the feed to the steam reformer, a carbon dioxide-rich recycle stream which is recycled to the carbon dioxide PSA unit feed and a carbon dioxide-rich product stream which is introduced under pressure to a liquifier. A waste stream from the liquifier is recylced to the carbon dioxide PSA unit feed. A portion of the carbon dioxide-rich product stream is withdrawn from the compressor at a stage such that its pressure is higher than that of the carbon dioxide PSA unit and returned thereto as a cocurrent purge preceding bed regeneration to obtain product.

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Wokingham, United Kingdom

Alan G Stokley