Hydromethanation of a carbonaceous feedstock with improved carbon utilization and power generation
AssigneeGreatpoint Energy, Inc.
InventorsAvinash Sirdeshpande, Earl T. Robinson, Pattabhi K. Raman, Kenneth Keckler
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Abstract
The present invention relates generally to processes for hydromethanating a carbonaceous feedstock in a hydromethanation reactor to a methane-enriched raw product stream, and more specifically to processing of solid char by-product removed from the hydromethanation reactor to improve the carbon utilization and thermal efficiency and economics of the overall process by co-producing electric power and steam from the by-product char in addition to the end-product pipeline quality substitute natural gas.
Claims14
A process for generating, from a non-gaseous carbonaceous material and a hydromethanation catalyst, (1) a fines-cleaned methane-enriched raw product gas stream, (2) an oxidation reactor product gas and (3) an oxidation reactor ash product stream, the process comprising the steps of:
- a) preparing a carbonaceous feedstock from the non-gaseous carbonaceous material;
- b) introducing the carbonaceous feedstock, the hydromethanation catalyst, steam and oxygen into a hydromethanation reactor, the hydromethanation reactor comprising a fluidized bed, a disengagement zone above the fluidized bed, and a gas mixing zone below the fluidized bed;
- c) reacting the carbonaceous feedstock in the hydromethanation reactor in the presence of carbon monoxide, hydrogen, steam and hydromethanation catalyst, and at an operating temperature from about 400° F. (about 205° C.) up to about 1500° F. (about 816° C.), and an operating pressure of at least about 250 psig (about 1825 kPa), to produce a methane-enriched raw product gas, heat energy and a by-product char;
- d) withdrawing a stream of methane-enriched raw product gas from the hydromethanation reactor as the methane-enriched raw product gas stream, wherein the methane-enriched raw product gas stream comprises methane, carbon monoxide, hydrogen, carbon dioxide, hydrogen sulfide, steam, and entrained solids;
- e) removing a substantial portion of the entrained solids from the methane-enriched raw product gas stream to generate a solids-depleted, methane-enriched raw product gas stream and a recovered primary solids stream;
- f) removing a substantial portion of any fines from the solids-depleted, methane-enriched raw product gas stream to generate the fines-cleaned methane-enriched raw product gas stream and a recovered secondary fines stream;
- g) withdrawing a stream of by-product char from the hydromethanation reactor as the hydromethanation reactor char product stream, wherein the hydromethanation reactor char product stream comprises a carbon content and entrained hydromethanation catalyst;
- h) extracting a portion of the entrained catalyst from the hydromethanation reactor char product stream by the steps of:
- (i) feeding all or a portion of the hydromethanation reactor char product stream to a catalyst recovery unit;
- (ii) withdrawing a stream of catalyst-depleted char from the catalyst recovery unit as the washed char product stream, the washed char product stream comprising a carbon content;
- and
- (iii) withdrawing a stream of liberated hydromethanation catalyst from the catalyst recovery unit as a recovered hydromethanation catalyst stream;
- i) feeding into an oxidation reactor (1) all or a portion of the washed char product stream, and (2) an oxygen-containing gas stream;
- j) reacting at least a portion of the carbon content of the washed char product stream with the oxygen-containing gas stream in the oxidation reactor to produce (1) an oxidation reactor ash product stream, and (2) an oxidation reactor product gas comprising steam and carbon dioxide;
- and
- k) withdrawing the oxidation reactor product gas from the oxidation reactor.
Dependencies are inferred from the claim text.