Two stage process for combusting fuel mixtures
AssigneesCatalytica, Inc., Tanaka Kikinzoku Kogyo K.K.
InventorsRalph A. Dalla Betta, Nobuyasu Ezawa, Kazunori Tsurumi, James C. Schlatter, Sarento G. Nickolas
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Abstract
This invention is a comparatively high pressure combustion process having a two stages in which a fuel is stepwise combusted using specific catalysts and catalytic structures and, optionally, having a final homogeneous combustion zone. The choice of catalysts and the use of specific structures, including those employing integral heat exchange, results in an overall catalyst structure which is stable due to its comparatively low temperature. The product combustion gas is at a temperature suitable for use in a gas turbine, furnace, boiler, or the like, but has low NO.sub.x content.
Claims27
A process for combusting combustible mixtures comprising the steps of:
- a. mixing an oxygen-containing gas with a fuel at a relatively high pressure to form a high pressure combustible mixture,
- b. contacting the high pressure combustible mixture in a first zone with a first zone combustion catalyst comprising palladium completely covering a catalyst support at reaction conditions sufficient to combust at least a portion but not all of the fuel,
- c. contacting the partially combusted gas from the first zone in a second catalytic zone with a second zone combustion catalyst having heat exchange surfaces comprising a metallic support with walls having palladium catalyst applied to at least a portion of only one side and not the other side of the surface forming the walls of the catalyst support so as to limit the catalyst substrate temperature and bulk outlet gas temperature at reaction conditions sufficient to combust at least a further portion of the fuel and produce a mixture capable of supporting homogeneous combustion.
A process for combusting combustible mixtures to produce a low NO.sub.x gas comprising the steps of:
- a. contacting a combustible mixture of a fuel and air at a pressure greater than four to five atmospheres in a first zone with a first zone combustion catalyst comprising palladium completely covering a metallic support at reaction conditions sufficient to combust at least a portion but not all of the fluid fuel and produce a partially combusted gas at a bulk and localized temperature no greater than about 800.degree. C., and
- b. contacting the partially combusted gas from the first zone in a second catalytic zone with a second zone combustion catalyst comprising palladium on a support structure having integral heat exchange surfaces comprising a metallic support with walls having the catalyst applied to at least a portion of only one side and not the other side of the surface forming the walls of the catalyst support structure so as to limit the catalyst substrate temperature and bulk outlet gas temperature at reaction conditions sufficient to combust at least a portion but not all of the fluid fuel and produce a partially combusted gas at a bulk temperature greater than the bulk temperature of the gas leaving the first zone but no greater than about 950.degree. C. but capable of supporting homogenous combustion.
A process for combusting combustible mixtures to produce a low NO.sub.x gas comprising the steps of:
- a. mixing methane and air at a pressure greater than about four to five atmospheres to produce a high pressure mixture,
- b. contacting the high pressure mixture in a first zone with a first zone combustion catalyst comprising palladium completely covering a metallic support at reaction conditions sufficient to combust at least a portion but not all of the methane and produce a partially combusted gas at a bulk and localized temperatures no greater than about 800.degree. C.,
- c. contacting the partially combusted gas from the first zone in a second catalytic zone with a second zone combustion catalyst comprising palladium on a support structure having integral heat exchange surfaces comprising a metallic support with walls having the catalyst applied to at least a portion of only one side and not the other side of the surface forming the walls of the catalyst support structure so as to limit the catalyst substrate temperature and bulk outlet gas temperature at reaction conditions sufficient to combust at least a portion but not all of the methane and produce a partially combusted gas at a bulk temperature greater than the bulk temperature of the gas leaving the first zone but no greater than about 950.degree. C. but capable of supporting homogenous combustion.
Dependencies are inferred from the claim text.