Hydromethanation of a carbonaceous feedstock with improved carbon utilization
First Claim
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1. A process for generating, from a non-gaseous carbonaceous material and a hydromethanation catalyst, (1) fines-cleaned methane-enriched raw product gas stream and (2) an oxidation reactor char product stream, the process comprising the steps of:
- a) preparing a carbonaceous feedstock from the non-gaseous carbonaceous material;
b) introducing the carbonaceous feedstock, a hydromethanation catalyst, steam and oxygen into a hydromethanation reactor, the hydromethanation reactor comprising a fluidized bed, an initial 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 a 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 by-product char stream, wherein the by-product char stream comprises a carbon content and entrained hydromethanation catalyst;
h) feeding all or a portion of the by-product char stream, oxygen and steam into an oxidation reactor integrated with the hydromethanation reactor or into a standalone oxidation reactor;
i) reacting at least a portion of the carbon content of the by-product char with oxygen and steam in the oxidation reactor at a temperature of about 1500°
F. (about 816°
C.) or less, to produce (1) an oxidation reactor char product stream comprising entrained hydromethanation catalyst, (2) an oxidation gas comprising steam, carbon monoxide, carbon dioxide, and hydrogen, and (3) heat energy;
j) withdrawing a stream of the oxidation gas from the standalone oxidation reactor, if present, as the oxidation gas stream and;
(1) feeding all or a portion of the oxidation gas stream into the hydromethanation reactor through an oxidation gas distributor plate, or(2) combining all or a portion of the oxidation gas stream with the methane-enriched raw product gas stream, or(3) combining all or a portion of the oxidation gas stream with the solids-depleted methane-enriched raw product gas stream, or(4) combining all or a portion of the oxidation gas stream with the fines-cleaned methane-enriched raw product gas stream, or(5) a combination thereof; and
k) withdrawing the oxidation reactor char product stream from the oxidation reactor.
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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 of the overall process and thereby lower the net costs of the end-product pipeline quality substitute natural gas.
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Citations
12 Claims
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1. A process for generating, from a non-gaseous carbonaceous material and a hydromethanation catalyst, (1) fines-cleaned methane-enriched raw product gas stream and (2) an oxidation reactor char product stream, the process comprising the steps of:
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a) preparing a carbonaceous feedstock from the non-gaseous carbonaceous material; b) introducing the carbonaceous feedstock, a hydromethanation catalyst, steam and oxygen into a hydromethanation reactor, the hydromethanation reactor comprising a fluidized bed, an initial 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 a 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 by-product char stream, wherein the by-product char stream comprises a carbon content and entrained hydromethanation catalyst; h) feeding all or a portion of the by-product char stream, oxygen and steam into an oxidation reactor integrated with the hydromethanation reactor or into a standalone oxidation reactor; i) reacting at least a portion of the carbon content of the by-product char with oxygen and steam in the oxidation reactor at a temperature of about 1500°
F. (about 816°
C.) or less, to produce (1) an oxidation reactor char product stream comprising entrained hydromethanation catalyst, (2) an oxidation gas comprising steam, carbon monoxide, carbon dioxide, and hydrogen, and (3) heat energy;j) withdrawing a stream of the oxidation gas from the standalone oxidation reactor, if present, as the oxidation gas stream and; (1) feeding all or a portion of the oxidation gas stream into the hydromethanation reactor through an oxidation gas distributor plate, or (2) combining all or a portion of the oxidation gas stream with the methane-enriched raw product gas stream, or (3) combining all or a portion of the oxidation gas stream with the solids-depleted methane-enriched raw product gas stream, or (4) combining all or a portion of the oxidation gas stream with the fines-cleaned methane-enriched raw product gas stream, or (5) a combination thereof; and k) withdrawing the oxidation reactor char product stream from the oxidation reactor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification