Processes for gasification of a carbonaceous feedstock

• US 8,647,402 B2
• Filed: 09/18/2009
• Issued: 02/11/2014
• Est. Priority Date: 09/19/2008
• Status: Active Grant

• Current Assignee: Sure Champion Investments Limited
• Original Assignee: GreatPoint Energy, Inc.
• Inventors: Robinson, Earl T., Lau, Francis S., Raman, Pattabhi K., Reiling, Vincent G., Dodson, Dwain, Rahman, Mustafiz, Nahas, Nicholas Charles
• Primary Examiner(s): Akram, Imran
• Application Number:
  US12/562,922
• Publication Number:
  US 20100071262A1
• Time in Patent Office: 1,607 Days
• Field of Search: None
• US Class Current: 48/197.FM
• CPC Class Codes: C01B 2203/0445 Selective methanation
• CPC Class Codes: C01B 2203/047 the impurity being carbon monoxide
• CPC Class Codes: C01B 3/586 the reaction being a methanation reaction
• CPC Class Codes: C10G 2/32 with the use of catalysts
• CPC Class Codes: C10J 2300/093 Coal
• CPC Class Codes: C10J 2300/0956 Air or oxygen enriched air
• CPC Class Codes: C10J 2300/0959 Oxygen
• CPC Class Codes: C10J 2300/0973 Water
• CPC Class Codes: C10J 2300/0986 Catalysts
• 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 2300/1687 with steam generation
• CPC Class Codes: C10J 2300/1807 Recycle loops, e.g. gas, solids, heating medium, water
• CPC Class Codes: C10J 2300/1884 with one stream being synthesis gas
• 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: C10L 3/08 Production of synthetic natural gas
• CPC Class Codes: C10L 3/102 of acid contaminants
• CPC Class Codes: C10L 9/10 : by using additives

Abstract

The present invention relates to processes and continuous processes for preparing gaseous products, and in particular, methane via the catalytic gasification of carbonaceous feedstocks in the presence of steam. In one aspect of the invention, the processes comprise at least partially combusting a first carbonaceous feedstock with an oxygen-rich gas stream in an oxygen-blown gasifier, under suitable temperature and pressure, to generate a first gas stream comprising hydrogen, carbon monoxide and superheated steam; and reacting a second carbonaceous feedstock and the first gas stream in a catalytic gasifier in the presence of a gasification catalyst under suitable temperature and pressure to form a second gas stream comprising a plurality of gaseous products comprising methane, carbon dioxide, hydrogen, carbon monoxide and hydrogen sulfide. The processes can comprise using at least one catalytic methanator to convert carbon monoxide and hydrogen in the gaseous products to methane and in certain embodiments do not recycle carbon monoxide or hydrogen to the gasifier.

Claims

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

(a) supplying to an oxygen-blown gasifier (i) a first carbonaceous feedstock, (ii) an oxygen-rich gas stream and (iii) an aqueous stream comprising water and/or steam;

(b) partially combusting the first carbonaceous feedstock with the oxygen-rich gas stream in the oxygen-blown gasifier, under suitable temperature and pressure, to generate a first gas stream comprising hydrogen, carbon monoxide and superheated steam;

(c) introducing a second carbonaceous feedstock, a gasification catalyst and the first gas stream to a catalytic gasifier, the catalytic gasifier in communication with the oxygen-blown gasifier;

(d) reacting the second carbonaceous feedstock and the first gas stream in the catalytic gasifier in the presence of the gasification catalyst, at a temperature of from about 450°

C. to about 800°

C. and a pressure of from about 400 psig to about 1000 psig, to form a second gas stream comprising a plurality of gaseous products comprising methane, carbon dioxide, hydrogen, carbon monoxide and hydrogen sulfide, wherein the second gas stream comprises at least about 50 mol % methane plus carbon dioxide, based on the moles of methane, carbon dioxide, carbon monoxide and hydrogen in the second gas stream;

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

(f) removing a substantial portion of the carbon dioxide and a substantial portion of the hydrogen sulfide from the second gas stream (or the methane-enriched second gas stream if present) to produce a third gas stream comprising a substantial portion of the methane from the second gas stream (or the methane-enriched second gas stream if present);

(g) optionally, if the third gas stream comprises hydrogen and greater than about 100 ppm carbon monoxide, reacting carbon monoxide and hydrogen present in the third gas stream in a catalytic methanator in the presence of a methanation catalyst to produce a methane-enriched third gas stream; and

(h) recovering the third gas stream (or the methane-enriched third gas stream if present),

wherein;

(i) at least one of step (e) and step (g) is present,

(ii) the third gas stream (or the methane-enriched third gas stream if present) is the methane product stream, or the third gas stream (or the methane-enriched third gas stream if present) is purified to generate the methane product stream, and

(iii) carbon monoxide in the second gas stream is subjected to a water-gas shift reaction in the presence of an aqueous medium to convert a portion of the carbon monoxide to carbon dioxide and to increase the fraction of hydrogen in the second gas stream.

2. The process of claim 1, wherein steps (a), (b), (c), (d), (f) and (h), and when present (e) and (g), are continuous.

3. The process of claim 1, wherein the gasification catalyst comprises an alkali metal gasification catalyst.

4. The process of claim 1, wherein the first and second carbonaceous feedstock each independently comprise one or more of anthracite, bituminous coal, sub-bituminous coal, lignite, petroleum coke, asphaltenes, liquid petroleum residues or biomass.

5. The process of claim 1, wherein the second carbonaceous feedstock is loaded with a gasification catalyst prior to introduction into the catalytic gasifier.

6. The process of claim 5, wherein the second carbonaceous feedstock is loaded with an amount of an alkali metal gasification catalyst sufficient to provide a ratio of alkali metal atoms to carbon atoms ranging from about 0.01 to about 0.10.

7. The process of claim 1, wherein the second carbonaceous feedstock, gasification catalyst and first gas stream are introduced into a plurality of catalytic gasifiers.

8. The process of claim 7, wherein a single oxygen-blown gasifier supplies the first gas stream to the plurality of catalytic gasifiers.

9. The process of claim 1, wherein the hydrogen and carbon monoxide are present in the first gas stream in a molar ratio of about 3:

1.

11. The process of claim 1, wherein step (e) is present.

12. The process of claim 1, wherein step (g) is present.

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

14. The process of claim 1, wherein no carbon fuel-fired superheater is present.

15. The process of claim 1, wherein the second gas stream comprises at least about 20 mol % methane based on the moles of methane, carbon dioxide, carbon monoxide and hydrogen in the second gas stream.

10. The process of clam 1, wherein the methane product stream is a pipeline-quality natural gas.