Sour shift process for the removal of carbon monoxide from a gas stream

• US 8,192,716 B2
• Filed: 03/31/2009
• Issued: 06/05/2012
• Est. Priority Date: 04/01/2008
• Status: Active Grant

• Current Assignee: Sure Champion Investments Limited
• Original Assignee: GreatPoint Energy, Inc.
• Inventors: Raman, Pattabhi K., Lau, Francis S., Robinson, Earl T.
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US12/415,050
• Publication Number:
  US 20090246120A1
• Time in Patent Office: 1,162 Days
• Field of Search: 423/648.1, 423/650, 423/651, 423/652, 423/653, 423/654, 423/437.2, 423/655, 252/373, 585/733, 585/721, 585/700
• US Class Current: 423/648.1
• CPC Class Codes: C01B 2203/0205 containing a reforming step
• CPC Class Codes: C01B 2203/0283 containing a CO-shift step, i.e. a water gas shift step
• CPC Class Codes: C01B 2203/04 containing a purification step for the hydrogen or the synthesis gas
• CPC Class Codes: C01B 2203/0405 Purification by membrane separation
• CPC Class Codes: C01B 2203/0415 Purification by absorption in liquids
• CPC Class Codes: C01B 2203/0435 Catalytic purification
• CPC Class Codes: C01B 2203/0445 Selective methanation
• CPC Class Codes: C01B 2203/046 Purification by cryogenic separation
• CPC Class Codes: C01B 2203/0465 Composition of the impurity
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/048 the impurity being an organic compound
• CPC Class Codes: C01B 2203/0485 the impurity being a sulfur compound
• CPC Class Codes: C01B 2203/1241 Natural gas or methane
• CPC Class Codes: C01B 2203/147 Three or more purification steps in series
• CPC Class Codes: C01B 3/12 by reaction of water vapour with carbon monoxide
• CPC Class Codes: C01B 3/34 by reaction of hydrocarbons with gasifying agents
• CPC Class Codes: C01B 3/50 Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification C01B3/14 takes precedence
• CPC Class Codes: C01B 3/52 by contacting with liquids; Regeneration of used liquids C01B3/508 takes precedence
• CPC Class Codes: C10J 2300/0903 Feed preparation
• CPC Class Codes: C10J 2300/094 Char
• CPC Class Codes: C10J 2300/0959 : Oxygen
• CPC Class Codes: C10J 2300/0966 : Hydrogen
• CPC Class Codes: C10J 2300/0973 : Water
• CPC Class Codes: C10J 2300/1662 : to methane
• CPC Class Codes: C10J 2300/1687 : with steam generation
• CPC Class Codes: C10J 2300/1807 : Recycle loops, e.g. gas, solids, heating medium, water
• CPC Class Codes: C10J 2300/1823 : for synthesis gas
• CPC Class Codes: C10J 2300/1846 : Partial oxidation, i.e. injection of air or oxygen only
• CPC Class Codes: C10J 2300/1853 : Steam reforming, i.e. injection of steam only
• CPC Class Codes: C10J 3/00 : Production of combustible gases containing carbon monoxide from solid carbonaceous fuels destructive distillation processes C10B
• CPC Class Codes: C10J 3/482 : Gasifiers with stationary fluidised bed
• CPC Class Codes: C10J 3/72 : Other features
• CPC Class Codes: C10J 3/721 : Multistage gasification, e.g. plural parallel or serial gasification stages
• CPC Class Codes: C10J 3/82 : Gas withdrawal means
• CPC Class Codes: C10K 3/04 : reducing the carbon monoxide content , e.g. water-gas shift [WGS]
• CPC Class Codes: C10L 3/10 : Working-up natural gas or synthetic natural gas

Abstract

Processes for the catalytic conversion of a carbonaceous composition into a gas stream comprising methane are provided, where a sour shift reaction is used to remove carbon monoxide gas stream produced by the gasification process. The incorporation of the sour shift reaction provides an efficient and cost-effective means of eliminating carbon monoxide from the gas stream. In addition, the sour shift reaction also generates additional hydrogen, thus increasing the amount of hydrogen produced from the gasification process.

Claims

1. A process for converting a carbonaceous feedstock into a plurality of gaseous products contained in a gas stream, and for separating hydrogen and methane from the other gaseous products in the gas stream, the process comprising the steps of:

(a) supplying a first carbonaceous feedstock to a reactor;

(b) at least partially combusting the first carbonaceous feedstock in the reactor in the presence of oxygen and under suitable temperature and pressure so as to generate (i) heat energy and (ii) a combustion gas stream comprising hydrogen, carbon monoxide, and carbon dioxide;

(c) using the heat energy from the combustion of the first carbonaceous feedstock to generate steam;

(d) introducing at least a portion of the steam, at least a portion of the combustion gas stream, a second carbonaceous feedstock, and a gasification catalyst to a gasification reactor;

(e) reacting the second carbonaceous feedstock in the gasification reactor in the presence of steam and the gasification catalyst, and under suitable temperature and pressure to form a first gas stream comprising methane, hydrogen, carbon monoxide, carbon dioxide, and one or more additional gaseous by-products;

(f) contacting the first gas stream with an aqueous medium to convert a substantial portion of the carbon monoxide in the first gas stream into carbon dioxide and generate hydrogen, thereby forming a carbon monoxide-depleted gas stream comprising methane, hydrogen, carbon dioxide, and one or more additional gaseous by-products;

(g) removing a substantial portion of the carbon dioxide and a substantial portion of the one or more gaseous by-products from the carbon monoxide-depleted gas stream to form a second gas stream comprising methane and hydrogen; and

(h) at least partially separating the hydrogen in the second gas stream and the methane in the second gas stream from each other to form at least a hydrogen-enriched gas stream and a first methane-enriched gas stream.

2. The process according to claim 1, wherein the first methane-enriched gas stream comprises methane, optionally carbon monoxide, and up to about 4 mol % hydrogen;

and wherein, if the heating value of the first methane-enriched gas stream is less than 950 btu/scf (dry basis), and if the first-methane-enriched gas stream comprises 1000 ppm or more of carbon monoxide;

(1) at least partially separating carbon monoxide from the first methane-enriched gas stream to form (i) a carbon-monoxide-enriched gas stream and (ii) a second methane-enriched gas stream having a heating value of at least 950 btu/scf (dry basis);

or (2) at least partially methanating the carbon monoxide in the first methane-enriched gas stream to form a second methane-enriched gas stream.

3. The process of claim 1, wherein the first carbonaceous feedstock and the second carbonaceous feedstock have substantially the same composition.

4. The process of claim 1, wherein the first carbonaceous feedstock and the second carbonaceous feedstock have different compositions.

5. The process of claim 1, wherein the first carbonaceous feedstock, the second carbonaceous feedstock, or both the first carbonaceous feedstock and the second carbonaceous feedstock are in a particulate form.

6. The process of claim 1, wherein the first carbonaceous feedstock is in the form of an aqueous slurry.

7. The process of claim 1, wherein the reactor is either a gasification reactor or an oxygen combustor.

8. The process of claim 1, wherein, in step (c), the steam is generated within the reactor.

9. The process of claim 1, wherein, in step (c), the heat energy is transferred to a heat exchanger which generates steam upon contact with water.

10. The process of claim 1, further comprising the step of introducing at least a portion of the steam generated in step (c) into a steam turbine to generate electricity.

11. The process of claim 1, wherein substantially all of the steam generated in step (c) is introduced into the gasification reactor.

12. The process of claim 1, wherein the gasification catalyst is an alkali metal gasification catalyst.

13. The process of claim 1, wherein a char is formed in step (e), and the char is removed from the gasification reactor and sent to a catalyst recovery and recycle process.

14. The process of claim 13, wherein the gasification catalyst comprises gasification catalyst recycled from the catalyst recovery and recycle process.