Processes For Hydromethanation Of A Carbonaceous Feedstock

• US 20100292350A1
• Filed: 05/12/2010
• Published: 11/18/2010
• Est. Priority Date: 05/13/2009
• Status: Active Grant

• Current Assignee: Sure Champion Investments Limited
• Original Assignee: GreatPoint Energy, Inc.
• Inventors: Robinson, Earl T., Raman, Pattabhi K., Reiling, Vincent G.
• Granted Patent: US 8,268,899 B2
• Time in Patent Office: Days
• US Class Current: 518/700
• CPC Class Codes: C01B 32/40 Carbon monoxide
• CPC Class Codes: C01B 32/50 Carbon dioxide
• CPC Class Codes: C10G 2/32 with the use of catalysts
• CPC Class Codes: C10G 2300/207 Acid gases, e.g. H2S, COS, SO2, HCN
• CPC Class Codes: C10G 2300/805 Water
• CPC Class Codes: C10G 2300/807 Steam
• CPC Class Codes: C10J 2300/0959 Oxygen
• CPC Class Codes: C10J 2300/0973 Water
• CPC Class Codes: C10J 2300/1662 to methane (SNG) production of synthetic natural gas C10L3/08
• CPC Class Codes: C10J 2300/1671 with the production of electricity
• CPC Class Codes: C10J 2300/1675 making use of a steam turbine
• CPC Class Codes: C10J 2300/1678 with air separation separating gases using rectification of air F25J3/04521
• 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 2300/1846 Partial oxidation, i.e. injection of air or oxygen only
• CPC Class Codes: C10J 2300/1884 with one stream being synthesis gas
• CPC Class Codes: C10J 2300/1892 with one stream being water/steam
• 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 3/721 Multistage gasification, e.g. plural parallel or serial gasification stages
• CPC Class Codes: C10J 3/84 : with means for removing dust or tar from the gas
• CPC Class Codes: C10J 3/86 : combined with waste-heat boilers
• CPC Class Codes: C10K 1/003 : of acid contaminants, e.g. acid gas removal
• CPC Class Codes: C10K 1/004 : Sulfur containing contaminants, e.g. hydrogen sulfide
• CPC Class Codes: C10K 1/04 : by cooling to condense non-gaseous materials C10K1/001 takes precedence
• CPC Class Codes: C10K 1/101 : with water only
• CPC Class Codes: C10K 1/102 : containing free acid
• CPC Class Codes: C10K 1/14 : organic
• CPC Class Codes: C10K 1/143 : containing amino groups
• CPC Class Codes: C10K 1/16 : with non-aqueous liquids
• CPC Class Codes: C10K 1/165 : at temperatures below zero degrees Celsius
• CPC Class Codes: C10K 1/20 : by treating with solids; Regenerating spent purifying masses separation by adsorption B01D53/02; separation by chemical reaction B01D53/34; refining of hydrocarbon oils with acids C10G17/02, C10G27/02, C10G29/12
• CPC Class Codes: C10K 1/32 : with selectively adsorptive solids, e.g. active carbon
• CPC Class Codes: C10K 3/04 : reducing the carbon monoxide content , e.g. water-gas shift [WGS]
• CPC Class Codes: C10L 3/08 : Production of synthetic natural gas

Abstract

The present invention relates to processes for preparing gaseous products, and in particular methane, via the catalytic hydromethanation of a carbonaceous feedstock in the presence of steam, syngas and an oxygen-rich gas stream.

Claims

1. A process for generating a plurality of gaseous products from a carbonaceous feedstock, and generating a methane product stream, the process comprising the steps of:

(a) supplying a first carbonaceous feedstock, a first oxygen-rich gas stream and, optionally, an aqueous stream comprising one or both of water and steam, to a syngas generator;

(b) reacting the first carbonaceous feedstock in the presence of oxygen and, optionally, the aqueous stream, in the syngas generator, at a first temperature and a first pressure, to produce a first gas stream comprising hydrogen, carbon monoxide and, optionally, steam;

(c) cooling the first gas stream, optionally with a quench stream comprising one or both of water and steam, to generate a cooled first gas stream comprising hydrogen, carbon monoxide and steam at a second temperature and a second pressure;

(d) introducing a second carbonaceous feedstock, a hydromethanation catalyst, a second oxygen-rich gas stream and the cooled first gas stream to a hydromethanation reactor, the second carbonaceous feedstock comprising a carbon content;

(e) reacting a portion of the carbon content from the second carbonaceous feedstock in the hydromethanation reactor in the presence of oxygen to produce carbon monoxide, hydrogen and heat energy;

(f) reacting the second carbonaceous feedstock in the hydromethanation reactor in the presence of carbon monoxide, hydrogen, steam and hydromethanation catalyst, at a third temperature and a third pressure, to produce a methane-enriched raw product stream comprising methane, carbon monoxide, hydrogen and carbon dioxide;

(g) withdrawing the methane-enriched product stream from the hydromethanation reactor; and

(h) treating the methane-enriched product stream to generate the methane product stream.

2. The process of claim 1, wherein the amount of the second oxygen-rich stream introduced into the hydromethanation reactor is varied to assist control of the third temperature.

3. The process of claim 1, wherein the methane-enriched raw product stream comprises at least about 20 mol % methane (based on the moles of methane, carbon dioxide, carbon monoxide and hydrogen in the methane-enriched raw product stream).

4. The process of claim 1, wherein the methane-enriched raw product stream comprises at least 50 mol % methane plus carbon dioxide (based on the moles of methane, carbon dioxide, carbon monoxide and hydrogen in the methane-enriched raw product stream).

5. The process of claim 1, wherein steam is supplied to the syngas generator, and the first gas stream further comprises steam.

6. The process of claim 1, wherein the first carbonaceous feedstock is an aqueous slurry, and the first gas stream further comprises steam.

7. The process of claim 1, wherein an ash by-product is generated in step (b), which is continuously or periodically withdrawn from the syngas generator.

8. The process of claim 1, wherein the second carbonaceous feedstock is loaded with hydromethanation catalyst prior to being supplied to the hydromethanation reactor.

9. The process of claim 1, wherein the hydromethanation catalyst comprises an alkali metal.

10. The process of claim 1, wherein a char by-product is generated in steps (e) and (f), which is continuously or periodically withdrawn from the hydromethanation reactor.

11. The process of claim 10, wherein the hydromethanation catalyst comprises an alkali metal, the char by-product comprises an alkali metal content from the hydromethanation catalyst, at least a portion of the char by-product is treated to recover at least a portion of the alkali metal content, and at least a portion of the recovered alkali metal content is recycled for use as hydromethanation catalyst.

12. The process of claim 11, wherein the second carbonaceous feedstock is impregnated with hydromethanation catalyst prior to being supplied to the hydromethanation reactor, and the hydromethanation catalyst used to impregnate the second carbonaceous feedstock comprises recycled hydromethanation catalyst and a make-up hydromethanation catalyst.

13. The process of claim 1, wherein a char by-product is generated in steps (e) and (f), the hydromethanation reactor comprises a collection zone where the char by-product collects, and the second oxygen-rich gas stream is introduced into this collection zone of the hydromethanation reactor.

14. The process of claim 1, wherein the first and second carbonaceous feedstocks comprise different carbonaceous materials.

15. The process of claim 1, wherein the first and second carbonaceous feedstocks derive from the same carbonaceous material.

16. The process of claim 1, further comprising the step of processing the methane product stream to generate a pipeline-quality natural gas product.

17. The process of claim 1, which is a continuous process in which steps (a), (b), (c), (d), (e), (f), (g) and (h) are performed in a continuous manner.

18. The process of claim 1, wherein a single syngas generator supplies the first gas stream to a plurality of hydromethanation reactors.

19. The process of claim 1, further comprising the steps of:

(i) recovering at least portion of the heat energy from the methane-enriched raw product stream to produce a cooled methane-enriched raw product stream and, optionally, utilizing the recovered heat energy to generate process steam;

(j) optionally recovering ammonia, if any, from the cooled methane-enriched raw product stream;

(k) in the event that the molar ratio of hydrogen to carbon monoxide in the cooled methane-enriched raw product stream is less than about 3;

1, optionally sour shifting a portion of the carbon monoxide in the cooled methane-enriched raw product stream to generate heat energy and a hydrogen-enriched second gas stream having a molar ratio of hydrogen to carbon monoxide of at least about 3;

1;

(l) optionally recovering a portion of the heat energy from step (k), if present, wherein at least a portion of the recovered heat energy is utilized to generate process steam;

(m) optionally reacting at least a portion of the carbon monoxide and at least a portion of the hydrogen present in the cooled methane-enriched raw product stream in a catalytic methanator in the presence of a sulfur-tolerant methanation catalyst to produce a methane-enriched second gas stream;

(n) optionally recovering a portion of the heat energy from step (m), if present, wherein a least a portion of the recovered heat energy is utilized to generate process steam;

(o) removing a substantial portion of the carbon dioxide and a substantial portion of the hydrogen sulfide from the cooled methane-enriched raw product stream to produce a sweetened gas stream comprising a substantial portion of the methane from the cooled methane-enriched raw product stream;

(p) optionally separating at least a portion of hydrogen from the sweetened gas stream to produce a hydrogen-depleted third gas stream;

(q) optionally reacting carbon monoxide and hydrogen present in the sweetened gas stream in a catalytic methanator in the presence of a methanation catalyst to produce heat energy and a methane-enriched sweetened gas stream;

(r) optionally recovering a portion of the heat energy from step (q), wherein at least a portion of the recovered heat energy is utilized to generate process steam; and

(s) recovering at least a portion of the methane-enriched sweetened gas stream.

20. The process of claim 18, wherein steps (q) and (r) are present.

21. The process of claim 18, wherein step (k) is present.

22. The process of claim 1, which is a once-through process.