Cryogenic separation of synthesis gas

Patent metadata

Field	Value
Publication number	US-9909803-B2
Application number	US-201614997642-A
Country	US
Kind code	B2
Filing date	Jan 18, 2016
Priority date	Apr 1, 2009
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A process and apparatus for separating a feed containing hydrogen, carbon monoxide, methane, and optionally nitrogen to form a product gas having a desired H 2 :CO molar ratio and optionally a hydrogen product gas and a carbon monoxide product gas. The feed is partially condensed to form a hydrogen-enriched vapor fraction and a carbon monoxide-enriched liquid fraction. The hydrogen-enriched vapor fraction and carbon monoxide-enriched liquid fraction are combined in a regulated manner to form an admixture, which is cryogenically separated to form the product mixture having the desired H 2 :CO molar ratio.

First claim

We claim:

1. A process for separating a feed comprising hydrogen, carbon monoxide, methane, and optionally nitrogen, comprising:
partially condensing the feed to provide a hydrogen-enriched vapor fraction and a carbon monoxide-enriched liquid fraction;
combining at least a portion of the carbon monoxide-enriched liquid fraction with a regulated portion of the hydrogen-enriched vapor fraction to form a two-phase admixture having a vapor fraction and a liquid fraction;
cryogenically separating at least a portion of the two-phase admixture in a first fractionator to form a methane-depleted vapor fraction and a hydrogen-depleted liquid fraction;
partially condensing the methane-depleted vapor fraction to form a first product gas and a condensate, wherein the first product gas has a H 2 :CO molar ratio between 0.5:1 and 2.5:1; and
introducing at least a portion of the condensate into the first fractionator as reflux;
scrubbing a second portion of the hydrogen-enriched vapor fraction with a liquid methane wash stream to provide a hydrogen product gas and a carbon monoxide-loaded methane liquid;
wherein at least one of the liquid fraction of the two-phase admixture and the at least a portion of the carbon monoxide-enriched liquid fraction are partially vaporized.

2. The process of claim 1 wherein the first product gas H 2 :CO molar ratio is between 0.9:1 and 1.5:1.

3. The process of claim 1 further comprising:
stripping hydrogen from a second portion of the carbon monoxide-enriched liquid fraction and at least a portion of the hydrogen-depleted liquid fraction in a second fractionator to form a second hydrogen-enriched vapor fraction and a hydrogen-freed liquid fraction; and
separating an intermediate feed comprising carbon monoxide and methane in a carbon monoxide/methane fractionator to form a carbon monoxide product gas and a methane-enriched liquid fraction, wherein the intermediate feed is formed from at least a portion of the hydrogen-freed liquid fraction.

4. The process of claim 3 further comprising:
condensing a CO-containing vapor feed to provide a CO-containing condensate; and
introducing at least a portion of the CO-containing condensate into the carbon monoxide/methane fractionator as reflux.

5. The process of claim 3 further comprising:
forming at least a portion of the liquid methane wash stream from a portion of the methane-enriched liquid fraction.

Assignees

• Air Prod & Chem

Inventors

• Mcneil Brian Alfred
• Weaver Andrew
• Winter David Graham

Classifications

• F25J3/0223 Primary

  H2/CO mixtures, i.e. synthesis gas; Water gas or shifted synthesis gas (production of carbon monoxide containing gas in general C01B32/40, C10J, C10K; production of hydrogen containing gas C01B3/00) · CPC title

• F25J2270/24

  Quasi-closed internal or closed external carbon monoxide refrigeration cycle · CPC title

• F25J3/0261

  separation of carbon monoxide (production of carbon monoxide containing gas in general C01B32/40, C10J, C10K) · CPC title

• C01B2203/146

  At least two purification steps in series · CPC title

• C01B2203/147

  Three or more purification steps in series · CPC title