Integrated coal drying and steam gasification process
First Claim
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1. A process for drying an aqueous slurry of carbonaceous solids containing water-soluble gasification catalyst constituents and subsequently gasifying the dried solids which comprises:
- (a) contacting said aqueous slurry of carbonaceous solids containing said water-soluble gasification catalyst constituents with superheated steam in a fluidized bed drying zone, said superheated steam having a temperature sufficiently higher than the temperature in said drying zone to convert more than about 80 weight percent of the water in said slurry into steam and to deposit said water-soluble gasification catalyst constituents onto said carbonaceous solids;
(b) withdrawing carbonaceous solids of reduced water content and impregnated with said gasification catalyst constituents from said drying zone and passing said solids to a gasification zone maintained at gasification conditions;
(c) withdrawing steam from said drying zone and passing at least a portion of said steam to said gasification zone; and
(d) gasifying said catalyst impregnated carbonaceous solids in said gasification zone with said steam passed to said gasification zone.
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Abstract
Carbonaceous solids slurried in an aqueous solution, which preferably contains catalyst constituents having gasification activity, are dried by contacting the slurry with superheated steam in a fluid bed slurry dryer and the resultant dried solids are subsequently gasified with steam generated in the dryer.
84 Citations
26 Claims
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1. A process for drying an aqueous slurry of carbonaceous solids containing water-soluble gasification catalyst constituents and subsequently gasifying the dried solids which comprises:
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(a) contacting said aqueous slurry of carbonaceous solids containing said water-soluble gasification catalyst constituents with superheated steam in a fluidized bed drying zone, said superheated steam having a temperature sufficiently higher than the temperature in said drying zone to convert more than about 80 weight percent of the water in said slurry into steam and to deposit said water-soluble gasification catalyst constituents onto said carbonaceous solids; (b) withdrawing carbonaceous solids of reduced water content and impregnated with said gasification catalyst constituents from said drying zone and passing said solids to a gasification zone maintained at gasification conditions; (c) withdrawing steam from said drying zone and passing at least a portion of said steam to said gasification zone; and (d) gasifying said catalyst impregnated carbonaceous solids in said gasification zone with said steam passed to said gasification zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A process for drying an aqueous slurry of carbonaceous solids and subsequently catalytically gasifying the dried solids which comprises:
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(a) mixing carbonaceous solids with an aqueous solution containing water-soluble gasification catalyst constituents to form said aqueous slurry of carbonaceous solids; (b) contacting said aqueous slurry of carbonaceous solids with superheated steam in a fluidized bed drying zone, said superheated steam having a temperature sufficiently higher than the temperature in said drying zone to convert more than about 80 weight percent of the water in said slurry into steam and to deposit said water-soluble gasification catalyst constituents onto said carbonaceous solids; (c) withdrawing carbonaceous solids having a reduced water content and impregnated with said gasification catalyst constituents from said drying zone and passing said solids to a gasification zone maintained at catalytic steam gasification conditions; (d) withdrawing steam from said drying zone and passing a portion of said steam to said gasification zone; (e) gasifying said catalyst impregnated carbonaceous solids in said gasification zone with said steam passed to said gasification zone to produce char particles containing catalyst residues and a gaseous effluent containing unreacted steam; (f) contacting said char particles with an aqueous leaching agent to form an aqueous solution of water-soluble gasification catalyst constituents; and (g) using said aqueous solution from step (f) in step (a) to form said aqueous slurry of carbonaceous solids. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A process for drying an aqueous slurry of coal and subsequently catalytically gasifying the dried coal which comprises:
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(a) mixing coal with an aqueous solution containing water-soluble gasification catalyst constituents to form said aqueous slurry of coal; (b) contacting said aqueous slurry of coal with superheated steam in a fluidized bed drying zone, said superheated steam having a temperature sufficiently higher than the temperature in said drying zone to convert more than about 80 weight percent of the water in said slurry into steam and to simultaneously deposit said water-soluble gasification catalyst constituents onto said coal; (c) withdrawing coal having a reduced water content and impregnated with said gasification catalyst constituents from said drying zone and passing said coal to a gasification zone maintained at catalytic steam gasification conditions; (d) withdrawing steam from said drying zone; (e) passing a portion of said steam withdrawn from said drying zone through a superheater and recycling it to said drying zone to provide said superheated steam; (f) passing the remainder of said steam withdrawn from said drying zone to said gasification zone; (g) gasifying said catalyst impregnated coal in said gasification zone with said steam passed to said gasification zone to produce char particles containing catalyst residues and a gaseous effluent containing unreacted steam; (h) contacting said char particles with an aqueous leaching agent to form an aqueous solution of water-soluble gasification catalyst constituents; (i) using said aqueous solution from step (h) in step (a) to form said aqueous slurry of coal; (j) condensing said unreacted steam in said gaseous effluent from said gasification zone to produce sour water; and (k) using at least a portion of said sour water in step (a) to form said aqueous slurry of coal. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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Specification