Process and Apparatus for the Separation of Methane from a Gas Stream

• US 20090260287A1
• Filed: 02/27/2009
• Published: 10/22/2009
• Est. Priority Date: 02/29/2008
• Status: Abandoned Application

• Current Assignee: Sure Champion Investments Limited
• Original Assignee: GreatPoint Energy, Inc.
• Inventors: Lau, Francis S.
• Application Number:
  US12/395,330
• Publication Number:
  US 20090260287A1
• Time in Patent Office: Days
• US Class Current: 48/127.700
• CPC Class Codes: C01B 2203/0205 containing a reforming step
• CPC Class Codes: C01B 2203/04 containing a purification step for the hydrogen or the synthesis gas
• CPC Class Codes: C01B 2203/0415 Purification by absorption in liquids
• 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 2203/0485 the impurity being a sulfur compound
• CPC Class Codes: C01B 3/38 using catalysts
• 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: C10K 3/00 Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide
• CPC Class Codes: C10L 3/08 Production of synthetic natural gas
• CPC Class Codes: C10L 3/102 of acid contaminants
• CPC Class Codes: Y02P 30/00 Technologies relating to oil refining and petrochemical industry

Abstract

Processes for conversion of a carbonaceous composition into a gas stream comprising methane are provided, where an energy-efficient process and/or apparatus is used to separate methane out of a gas stream comprising methane, carbon monoxide, and hydrogen. Particularly, methane can be separated from hydrogen and carbon monoxide using novel processes and/or apparatuses that generate methane hydrates. Because hydrogen and carbon monoxide do not readily form hydrates, the methane is separated from a gas stream. The methane can be captured as a substantially pure stream of methane gas by dissociating the methane from the hydrate and separating out any residual water vapor.

Claims

1. An apparatus for separating methane from a gas stream, the apparatus comprising:

(a) a mixer configured to receive a gas stream and water and to generate a gas/water mixture, the gas stream comprising methane, carbon monoxide, and hydrogen;

(b) a hydrate reactor configured to receive the gas/water mixture, to generate a slurry comprising methane hydrate, and to exhaust a methane-depleted gas stream, the methane-depleted gas stream comprising carbon monoxide and hydrogen, the hydrate reactor comprising;

a reaction chamber;

a gas/water mixture inlet for supplying the gas/water mixture to the reaction chamber, the gas/water mixture inlet in communication with the mixer;

a gas outlet for exhausting a methane-depleted gas stream from the reaction chamber;

a slurry outlet for removing a slurry from the reaction chamber; and

a chiller for cooling the reaction chamber; and

(c) a separator configured to receive the slurry comprising methane hydrate, to dissociate the methane from the methane hydrate, and to exhaust methane, the separator comprising;

a separation chamber;

a slurry inlet for supplying the slurry into the separation chamber, the slurry inlet in communication with the hydrate reactor;

a methane gas outlet for exhausting methane from the separation chamber;

a water outlet for removing water from the chamber; and

a heater for heating the separation chamber.

2. The apparatus according to claim 1, wherein the mixer comprises:

a mixing chamber;

a gas stream inlet for supplying a gas stream to the mixing chamber;

a water inlet for supplying water to the mixing chamber;

a gas/water outlet for removing the gas/water mixture from the mixing chamber;

a mixing element for mixing the gas stream and water in the mixing chamber to form a gas/water mixture; and

a chiller for cooling the water entering the mixer.

3. The apparatus according to claim 1, further comprising a water source in communication with the mixer, the separator, or both.

4. The apparatus according to claim 1, further comprising a gas stream source in communication with the mixer.

5. The apparatus according to claim 4, further comprising a pump for pumping water from the water source to the mixer.

6. The apparatus according to claim 1, further comprising a pump for pumping slurry from the hydrate reactor to the separator.

7. A process for separating and recovering methane from a gas stream, the process comprising the steps of:

(a) providing a gas stream comprising methane, carbon monoxide and hydrogen;

(b) contacting the gas stream with water under suitable temperature and pressure to form a methane-depleted gas stream and a slurry comprising methane hydrate;

(c) recovering the slurry;

(d) heating the slurry under conditions sufficient to dissociate the methane from the methane hydrate; and

(e) recovering the methane under a pressure ranging from about 5 to about 80 atm.

8. The process according to claim 7, wherein step (b) is performed at a temperature ranging from about −

50°

C. to about 0°

C. and at a pressure ranging from about 10 atms to about 60 atms.

9. The process according to claim 7, wherein step (d) is performed at a temperature above about 0°

C., and at a pressure of about atmospheric pressure or above.

10. The process according to claim 7, wherein the step (b) water comprises a promoter.

11. The process according to claim 10, wherein the promoter is selected from the group consisting of tetrahydrofuran, 1,4-dioxane, and sodium lauryl sulfate.

12. The process according to claim 10, wherein step (b) is performed at a temperature ranging from about −

20°

C. to about 10°

C. and at a pressure ranging from about 5 atms to about 40 atms.

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

(a) supplying a carbonaceous composition to a gasification reactor;

(b) reacting the carbonaceous composition in the gasification reactor in the presence of steam and under suitable temperature and pressure to form a gas stream comprising methane and at least one or more of hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, and other higher hydrocarbons; and

(c) separating and recovering methane from the gas stream in accordance with the process of claim 7.

14. A process for separating and recovering carbon monoxide and hydrogen from a gas stream, the process comprising the steps of:

(a) providing a gas stream comprising methane, carbon monoxide, and hydrogen;

(b) contacting the gas stream with water under suitable temperature and pressure to form a slurry comprising methane hydrate, and a methane-depleted gas stream comprising carbon monoxide and hydrogen; and

(c) recovering the methane-depleted gas stream.

15. A continuous process for converting a carbonaceous feedstock into a plurality of gaseous products, the process comprising the steps of:

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

(b) reacting the carbonaceous feedstock in the gasifying reactor in the presence of steam and a gasification catalyst and under suitable temperature and pressure to form a first gas stream comprising a plurality of gaseous products comprising methane and at least one or more of hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia and other higher hydrocarbons;

(c) at least partially separating the plurality of gaseous products to produce a second gas stream comprising methane, carbon monoxide, and hydrogen;

(d) separating and recovering a methane-depleted gas stream comprising carbon monoxide and hydrogen in accordance with the process of claim 14; and

(e) recycling at least a portion of the carbon monoxide and hydrogen from the methane-depleted gas stream to the gasifying reactor.