Method of producing power

Abstract

A process for producing power from a fuel stream containing at least 30 mol % hydrogen sulfide is provided. The fuel stream is combusted with an oxidant stream containing molecular oxygen to generate a combusted gas stream containing thermal power, where the molar ratio of molecular oxygen to hydrogen sulfide is at least 1:1. Electrical power is generated from the thermal power of the combusted gas stream.

What is claimed: 
     
         1 . A method of producing power comprising combusting an oxidant stream and at least a portion of a fuel stream comprising one or more feed streams to generate a combusted gas stream containing thermal power, wherein the fuel stream has a hydrogen sulfide content of at least 30 mol %, at least 90 mass % of the components of the fuel stream are gaseous, the oxidant stream contains molecular oxygen, and the molar ratio of molecular oxygen to hydrogen sulfide is at least 1:1; and
 generating electrical power from the thermal power of the combusted gas stream.   
     
     
         2 . The method of  claim 1  wherein the molar ratio of molecular oxygen to hydrogen sulfide is from 1.3:1 to 1.7:1. 
     
     
         3 . The method of  claim 1  wherein electrical power is generated from the thermal power of the combusted gas stream by exchanging sufficient heat between the combusted gas stream and a liquid aqueous stream to convert the liquid aqueous stream to steam and to cool the combusted gas stream, where the cooled combusted gas stream is a flue gas stream comprising sulfur dioxide; expanding the steam through an expander to generate mechanical power and an expanded steam stream; and, converting the mechanical power to electrical power. 
     
     
         4 . The method of  claim 3 , further comprising the steps of exchanging heat between the expanded steam stream and a fluid having a boiling point at least 50° C. lower than the liquid of the liquid aqueous stream at 0.101 MPa and having a latent heat of vaporization of at least 350 kJ/kg to condense water from the expanded steam stream and to form a heat transfer gas from the fluid, where the heat transfer gas contains thermal power transferred from the expanded steam stream by heat exchange with the fluid;
 expanding the heat transfer gas through an expander to generate mechanical power and to form the fluid; and 
 generating electrical power from the mechanical power generated by expanding the heat transfer gas. 
 
     
     
         5 . The method of  claim 4  wherein a portion of the thermal power transferred from the expanded steam stream to the fluid is derived from the latent heat of condensation of water in the expanded steam stream. 
     
     
         6 . The method of  claim 4  wherein the fluid is selected from the group consisting of anhydrous ammonia, aqueous ammonia, anhydrous sulfur dioxide, carbon dioxide, and diethyl ether. 
     
     
         7 . The method of  claim 4  wherein the water condensed from the expanded steam stream has a temperature of at most 85° C. and is provided as the liquid aqueous stream to cool the combusted gas stream. 
     
     
         8 . The method of  claim 3 , wherein the flue gas stream further comprises steam and has a temperature of from greater than 100° C. to 150° C., further comprising the steps of exchanging heat between the flue gas stream and a fluid having a boiling point at least 50° C. lower than the liquid of the liquid aqueous stream at 0.101 MPa and having a latent heat of vaporization of at least 350 kJ/kg to cool the flue gas stream to a temperature of from greater than 0° C. to 50° C. and condense and separate water therefrom and to form a heat transfer gas from the fluid, where the heat transfer gas contains thermal power transferred from the flue gas stream to the fluid by heat exchange with the fluid;
 expanding the heat transfer gas through an expander to generate mechanical power and to form the fluid; and 
 generating electrical power from the mechanical power generated by expanding the heat transfer gas. 
 
     
     
         9 . The method of  claim 8 , wherein the fluid formed by expanding the heat transfer gas through an expander has a temperature of from −25° C. to −100° C., further comprising the steps of exchanging heat between the fluid having a temperature of from −25° C. to −100° C. and a scrubbing solvent in which sulfur dioxide, carbon dioxide, or both may be dissolved to chill the scrubbing solvent to a temperature of from −100° C. to 0° C. and to raise the temperature of the fluid to at least 0° C. without converting the fluid to a gas; and
 contacting the flue gas stream from which water has been separated with the chilled scrubbing solvent to separate sulfur dioxide, carbon dioxide, or both from the flue gas stream into the scrubbing solvent. 
 
     
     
         10 . The method of  claim 9  further comprising the steps of heating the chilled scrubbing solvent to a temperature at which sulfur dioxide, carbon dioxide, or both separate from the scrubbing solvent, and separating sulfur dioxide, carbon dioxide, or both from the scrubbing solvent. 
     
     
         11 . The method of  claim 10  further comprising the step of exchanging heat between the scrubbing solvent from which sulfur dioxide, carbon dioxide, or both have been separated and the fluid having a temperature of from −25° C. to −100° C. to chill the scrubbing solvent to temperature of from −100° C. to 0° C. and to heat the fluid to a temperature of at least 0° C. without converting the fluid to a gas. 
     
     
         12 . The method of  claim 1  wherein electrical power is generated from at least a portion of the thermal power of the combusted gas stream by expanding the combusted gas stream through an expander to generate mechanical power and an expanded combusted gas stream, and converting the mechanical power to electrical power. 
     
     
         13 . The method of  claim 12  wherein the molar ratio of molecular oxygen in the oxidant stream to hydrogen sulfide in the fuel stream is at least 2:1. 
     
     
         14 . The method of  claim 12  wherein electrical power is generated by exchanging heat between the expanded combusted gas stream and a liquid aqueous stream to convert the liquid aqueous stream to steam and to cool the expanded combusted gas stream, where the cooled expanded combusted gas stream is a flue gas stream comprising sulfur dioxide; expanding the steam through an expander to generate mechanical power and an expanded steam stream; and, converting the mechanical power to electrical power. 
     
     
         15 . The method of  claim 14 , further comprising the steps of exchanging heat between the expanded steam stream and a fluid having a boiling point at least 50° C. lower than the liquid of the liquid aqueous stream at 0.101 MPa and having a latent heat of vaporization of at least 350 kJ/kg to condense water from the expanded steam stream and to form a heat transfer gas from the fluid, where the heat transfer gas contains thermal power transferred from the expanded steam stream by heat exchange with the fluid;
 expanding the heat transfer gas through an expander to generate mechanical power and to form the fluid; and 
 generating electrical power from the mechanical power generated by expanding the heat transfer gas. 
 
     
     
         16 . The method of  claim 15  wherein the fluid is selected from the group consisting of anhydrous ammonia, aqueous ammonia, anhydrous sulfur dioxide, carbon dioxide, and diethyl ether. 
     
     
         17 . The method of  claim 15  wherein a portion of the thermal power transferred from the expanded steam stream to the fluid is derived from the latent heat of condensation of water in the expanded steam stream. 
     
     
         18 . The method of  claim 15  wherein the water condensed from the expanded steam stream has a temperature of at most 85° C. and is provided as the liquid aqueous stream to cool the expanded combusted gas stream. 
     
     
         19 . The method of  claim 14 , wherein the flue gas stream further comprises steam and has a temperature of from greater than 100° C. to 150° C., further comprising the steps of exchanging heat between the flue gas stream and a fluid having a boiling point at least 50° C. lower than the liquid of the liquid aqueous stream at 0.101 MPa and having a latent heat of vaporization of at least 350 kJ/kg to cool the flue gas stream to a temperature of from greater than 0° C. to 50° C. and condense and separate water therefrom and to form a heat transfer gas from the fluid, where the heat transfer gas contains thermal power transferred from the flue gas stream to the fluid by heat exchange with the fluid;
 expanding the heat transfer gas through an expander to generate mechanical power and to form the fluid; and 
 generating electrical power from the mechanical power generated by expanding the heat transfer gas. 
 
     
     
         20 . The method of  claim 19 , wherein the fluid formed by expanding the heat transfer gas through an expander has a temperature of from −25° C. to −100° C., further comprising the steps of exchanging heat between the fluid having a temperature of from −25° C. to −100° C. and a scrubbing solvent in which sulfur dioxide, carbon dioxide, or both may be dissolved to chill the scrubbing solvent to a temperature of from −100° C. to 0° C. and to raise the temperature of the fluid to at least 0° C. without converting the fluid to a gas; and
 contacting the flue gas stream from which water has been separated with the chilled scrubbing solvent to separate sulfur dioxide, carbon dioxide, or both from the flue gas stream into the scrubbing solvent. 
 
     
     
         21 . The method of  claim 20  further comprising the steps of heating the chilled scrubbing solvent to a temperature at which sulfur dioxide, carbon dioxide, or both separate from the scrubbing solvent and separating sulfur dioxide, carbon dioxide, or both from the scrubbing solvent. 
     
     
         22 . The method of  claim 21  further comprising the step of exchanging heat between the scrubbing solvent from which sulfur dioxide, carbon dioxide, or both have been separated and the fluid having a temperature of from −25° C. to −100° C. to chill the scrubbing solvent to a temperature of from −100° C. to 0° C. and to heat the fluid to a temperature of at least 0° C. without converting the fluid to a gas. 
     
     
         23 . The method of  claim 12  wherein the expanded combusted gas stream contains at least 5 vol. %, or at least 10 vol. % molecular oxygen, further comprising the steps of combusting a sulfur-containing fuel and the expanded combusted gas stream to generate a second combusted gas stream containing thermal power and generating electrical power from the thermal power of the second combusted gas stream. 
     
     
         24 . The method of  claim 23  further comprising the step of providing the sulfur-containing fuel for combustion in an amount effective to consume at least 99 mol % of the molecular oxygen in the expanded combusted gas stream. 
     
     
         25 . The method of  claim 23  wherein a portion of the fuel stream is provided as the sulfur-containing fuel. 
     
     
         26 . The method of  claim 23  wherein electrical power is generated by exchanging sufficient heat between the second combusted gas stream and a liquid aqueous stream to convert the liquid aqueous stream to steam and to cool the second combusted gas stream, where the cooled second combusted gas stream is a flue gas stream comprising sulfur dioxide; expanding the steam through an expander to generate mechanical power and an expanded steam stream; and converting the mechanical power to electrical power. 
     
     
         27 . The method of  claim 26 , further comprising the steps of exchanging heat between the expanded steam stream and a fluid having a boiling point at least 50° C. lower than the liquid of the liquid aqueous stream at 0.101 MPa and having a latent heat of vaporization of at least 350 kJ/kg to condense water from the expanded steam stream and to form a heat transfer gas from the fluid, where the heat transfer gas contains thermal power transferred from the expanded steam stream by heat exchange with the fluid;
 expanding the heat transfer gas through an expander to generate mechanical power and to form the fluid; and 
 generating electrical power from the mechanical power generated by expanding the heat transfer gas. 
 
     
     
         28 . The method of  claim 27  wherein the fluid is selected from the group consisting of anhydrous ammonia, aqueous ammonia, anhydrous sulfur dioxide, carbon dioxide, and diethyl ether. 
     
     
         29 . The method of  claim 27  wherein a portion of the thermal power transferred from the expanded steam stream to the fluid is derived from the latent heat of condensation of water in the expanded steam stream. 
     
     
         30 . The method of  claim 27  wherein the water condensed from the expanded steam stream has a temperature of at most 85° C. and is provided as the liquid aqueous stream to cool the second combusted gas stream. 
     
     
         31 . The method of  claim 26 , wherein the flue gas stream further comprises steam and has a temperature of from greater than 100° C. to 150° C., further comprising the steps of exchanging heat between the flue gas stream and a fluid having a boiling point at least 50° C. lower than the liquid of the liquid aqueous stream at 0.101 MPa and having a latent heat of vaporization of at least 350 kJ/kg to cool the flue gas stream to a temperature of from greater than 0° C. to 50° C. and condense and separate water therefrom and to form a heat transfer gas from the fluid, where the heat transfer gas contains thermal power transferred from the flue gas stream to the fluid by heat exchange with the fluid;
 expanding the heat transfer gas through an expander to generate mechanical power and to form the fluid; and 
 generating electrical power from the mechanical power generated by expanding the heat transfer gas. 
 
     
     
         32 . The method of  claim 31  wherein the fluid is selected from the group consisting of anhydrous ammonia, aqueous ammonia, anhydrous sulfur dioxide, carbon dioxide, and diethyl ether. 
     
     
         33 . The method of  claim 31 , wherein the fluid formed by expanding the heat transfer gas through an expander has a temperature of from −25° C. to −100° C., further comprising the steps of exchanging heat between the fluid having a temperature of from −25° C. to −100° C. and a scrubbing solvent in which sulfur dioxide, carbon dioxide, or both may be dissolved to chill the scrubbing solvent to a temperature of from −100° C. to 0° C. and to raise the temperature of the fluid to at least 0° C. without converting the fluid to a gas; and
 contacting the flue gas stream from which water has been separated with the chilled scrubbing solvent to separate sulfur dioxide, carbon dioxide, or both from the flue gas stream into the scrubbing solvent. 
 
     
     
         34 . The method of  claim 33  further comprising the steps of heating the chilled scrubbing solvent to a temperature at which sulfur dioxide, carbon dioxide, or both separate from the scrubbing solvent, and, separating sulfur dioxide, carbon dioxide, or both from the scrubbing solvent. 
     
     
         35 . The method of  claim 34  further comprising the step of exchanging heat between the scrubbing solvent from which sulfur dioxide or carbon dioxide has been separated and the fluid having a temperature of from −25° C. to −100° C. to chill the scrubbing solvent to a temperature of −100° C. to 0° C. and to heat the fluid to a temperature of at least 0° C. without converting the fluid to a gas.