System and process for generation of electrical power

Abstract

A system and process for generation of electrical power is provided. Electrical power is generated by a system including two integrated power cycles, a first power cycle utilizing water/steam as a working fluid and the second power cycle utilizing a fluid selected from the group consisting of molecular nitrogen, argon, a chemical compound having a boiling point of at most 65° C. at 0.101 MPa and a latent heat of vaporization of at least 350 kJ/kg, and a chemical compound having a boiling point of at most 65° C. at 0.101 MPa and a specific heat capacity as a liquid of at least 1.9 kJ/kg-° K as a working fluid. The working fluid of the second power cycle is expanded through a two-phase expander to produce power in the second power cycle, where the expanded working fluid of the second cycle has a vapor quality of at most 0.5.

What is claimed is: 
     
         1 . A system comprising:
 a water vapor stream comprising at least 50 mass % water and having a vapor quality of at least 0.80 or being superheated;   a fluid stream comprised of a fluid comprised of one or more constituents selected from the group consisting of molecular nitrogen, argon, a chemical compound having a boiling point of at most 65° C. at 0.101 MPa and a latent heat of vaporization of at least 350 kJ/kg, and a chemical compound having a boiling point of at most 65° C. at 0.101 MPa and a specific heat capacity as a liquid of at least 1.9 kJ/kg-° K, where the one or more constituents comprise at least 50 wt. % of the fluid and where the fluid is in liquid or supercritical phase;   a condenser structurally arranged to enable thermal contact of the water vapor stream and the fluid stream, the condenser also being structurally arranged to prevent direct physical contact of the water vapor stream and the fluid stream, wherein thermal contact of the water vapor stream and the fluid stream produces liquid water from the water vapor stream and produces a heated fluid stream comprised of the fluid in gaseous or supercritical phase, where the fluid in the heated fluid stream that is in gaseous phase has a vapor quality of at least 0.90 or is superheated;   a first expander system comprised of a two-phase expander stage, the first expander system being operatively coupled to the condenser to receive the heated fluid stream from the condenser and being structurally arranged to expand the heated fluid stream to produce mechanical power and an expanded fluid stream comprised of the fluid in liquid phase and having a vapor quality of at most 0.5 or being supercooled;   a first electrical power generating element operatively coupled to the first expander system to generate electrical power from the mechanical power produced by expanding the heated fluid stream through the first expander system.   
     
     
         2 . The system of  claim 1  further comprising:
 a heat recovery steam generator operatively coupled to a heat source and operatively coupled to the condenser to receive water from the condenser, the heat recovery steam generator being structurally arranged to thermally contact heat from the heat source with water to produce steam; 
 a second expander system operatively coupled to the heat recovery steam generator, to receive steam from the heat recovery steam generator and structurally arranged to expand the steam to produce mechanical power and the water vapor stream, where the condenser is operatively coupled to the second expander system to receive the water vapor stream from the second expander system; and 
 a second electrical power generating element operatively coupled to the second expander system to generate electrical power from the mechanical power produced by expanding the steam through the second expander system. 
 
     
     
         3 . The system of  claim 1  wherein the first expander system is further comprised of a vapor expander stage, where a vapor expander stage is operatively coupled to the condenser to receive the heated fluid stream from the condenser and is structured to expand the heated fluid stream and produce mechanical power from the expansion of the heated fluid stream, where the two-phase expander stage is operatively coupled the vapor expander stage to receive the expanded heated fluid stream from the vapor expander stage, and where the two-phase expander stage is structured to expand the expanded heated fluid stream to produce the expanded fluid stream and produce mechanical power from the expansion of the expanded heated fluid stream. 
     
     
         4 . The system of  claim 1  further comprising an expanded fluid stream pressure regulating valve operatively coupled to the first expander system to receive a gaseous phase fluid portion of the expanded fluid stream from the first expander system, wherein the expanded fluid stream pressure regulating valve is adjustable to regulate the pressure of the expanded fluid stream. 
     
     
         5 . The system of  claim 1  further comprising an expanded fluid stream gas-liquid separator operatively coupled to the two-phase expander of the first expander system to receive the expanded fluid stream from the two-phase expander, the expanded fluid stream gas-liquid separator being structurally arranged to separate a liquid phase fluid of the expanded fluid stream from a gaseous phase fluid of the expanded fluid stream; and
 an expanded fluid stream compressor, the expanded fluid stream compressor being operatively coupled to the expanded fluid stream gas-liquid separator to receive the gaseous phase fluid of the expanded fluid stream from the expanded fluid stream gas-liquid separator and being structured and arranged to compress the gaseous fluid portion of the expanded fluid stream to produce a converted liquid phase fluid stream, the expanded fluid stream compressor being operatively coupled to the condenser to to provide the converted liquid phase fluid stream to the condenser. 
 
     
     
         6 . The system of  claim 2  further comprising:
 a solvent effective for absorbing carbon dioxide or sulfur dioxide; 
 a heat exchanger operatively coupled to the first expander system to receive the expanded fluid stream from the first expander system and structurally arranged to thermally contact the expanded fluid stream and the solvent to cool the solvent and heat the expanded fluid stream to produce a regenerated fluid stream, where the heat exchanger is also operatively coupled to the condenser to provide the regenerated fluid stream to the condenser; 
 a scrubber operatively coupled to the heat exchanger to receive the cooled solvent from the heat exchanger and operatively coupled to the heat recovery steam generator to receive a flue gas stream containing carbon dioxide or sulfur dioxide from the heat recovery steam generator, where the flue gas stream is produced by thermal contact of a combusted gas stream from the heat source with water in the heat recovery steam generator, the scrubber being structurally arranged to directly physically contact the cooled solvent and the flue gas stream to separate at least a portion of the carbon dioxide or sulfur dioxide from the flue gas stream and capture at least a portion of the carbon dioxide or sulfur dioxide from the flue gas stream in the cooled solvent to produce a carbon dioxide-rich or a sulfur dioxide-rich solvent containing an increased amount of carbon dioxide or sulfur dioxide therein relative to the cooled solvent; 
 a second gas-liquid separator operatively coupled to the scrubber to receive the carbon dioxide-rich or sulfur dioxide-rich solvent from the scrubber and being structured and arranged to separate carbon dioxide or sulfur dioxide from the carbon dioxide-rich or sulfur dioxide-rich solvent to regenerate the solvent, where the heat exchanger is operatively coupled to the second gas-liquid separator to receive the regenerated solvent from the second gas-liquid separator. 
 
     
     
         7 . The system of  claim 2  wherein the heat source is a natural gas fired gas turbine. 
     
     
         8 . The system of  claim 2  wherein the heat source is a coal fired combustor. 
     
     
         9 . The system of  claim 2  wherein the heat source is an oil fired combustor. 
     
     
         10 . The system of  claim 2  wherein the heat source is nuclear fission. 
     
     
         11 . The system of  claim 2  wherein the heat source is geothermal. 
     
     
         12 . The system of  claim 1  further comprising a fluid stream pump operatively coupled to the first expander system to receive the liquid phase expanded fluid stream from the first expander system, and operatively coupled to the condenser to pump the liquid phase expanded fluid stream to the condenser, the fluid stream pump being structured and arranged to provide the liquid phase expanded fluid stream to the condenser at a selected mass flow rate and pressure. 
     
     
         13 . The system of  claim 2  further comprising a boiler feed water pump operatively connected to the condenser and to the heat recovery steam generator to pump water condensed in the condenser to the heat recovery steam generator, the boiler water feed pump being structured and arranged to provide the water to the condenser at a selected mass flow rate. 
     
     
         14 . The system of  claim 1  wherein the first expander system is operatively coupled to the condenser to provide the liquid phase expanded fluid stream to the condenser.