Solar fired combined cycle with supercritical turbine

Abstract

Mechanical work for electric power generation is obtained from thermal energy in a plant arranged for introduction of solar energy, available intermittently, by reflecting and concentrating solar radiation to directly heat a flow medium such as the exhaust gas from a combustion turbine directed into a steam generating boiler/evaporator. Steam generators and staged turbines recover and extract energy optimally at particular temperature, pressure and flow parameters in a closed thermodynamic cycle. Solar energy that is available intermittently is injected into the cycle to elevate the energy of the flow medium, in particular to produce supercritical steam. A steam turbine optimized for expanding supercritical steam is deployed during periods of available solar radiation by a controllable clutch and other switching and valve arrangements. The exhaust from the supercritical steam turbine can be coupled to downstream staged turbines optimized for successively lower pressures and higher flow rates.

What is claimed is: 
     
         1 . An apparatus for generating mechanical work from thermal energy, comprising:
 at least a first power generation component operable to produce at least one flow medium with an elevated energy state from which energy can be extracted;   at least one energy extraction component operable to extract mechanical work from the flow medium, extraction of such energy reducing the flow medium to a less elevated energy state;   a flowpath defined for the flow medium from the first power generation component to the energy extraction component;   a solar concentrator operable when solar radiation is available to direct solar heat energy into the flow medium along the flowpath, thereby increasing the elevated energy state of the flow medium.   
     
     
         2 . An electric power generation system comprising:
 at least one steam generator coupled in a recirculating flow path to supply a production flow of steam at nominal production pressure and temperature to a main steam turbine, the main steam turbine being mechanically coupled to an electric generator for generation of electric power by extracting energy from expansion of the production flow of steam;   wherein at least one additional steam turbine is coupled to the recirculating flow path and operated at a second production pressure and temperature that are one of a higher energy state than the nominal production pressure and temperature;   a solar collector configured to apply concentrated solar radiation to at least one zone along the recirculating flow path during periods of sufficient available solar energy, the solar collector increasing a pressure and temperature at said zone to the second production pressure and temperature; and,   a controller coupled to sensors assessing the condition of steam from the recirculating flow path and operating at least one valve for selectively deploying the additional steam turbine.   
     
     
         3 . The electric power generation system of  claim 2 , wherein the additional steam turbine is mechanically coupled to contribute torque to turn the electric generator, and further comprising a synchronizing clutch operated by the controller. 
     
     
         4 . The electric power generation system of  claim 3 , wherein the additional turbine is configured to operate at a said second production pressure and temperature that are higher than the nominal production pressure and temperature, and wherein an exhaust from the additional turbine is coupled into the recirculating flow path upstream from the main steam turbine. 
     
     
         5 . The electric power generation system of  claim 2 , wherein the additional turbine is configured to expand steam boosted in pressure and temperature by the solar collector. 
     
     
         6 . The electric power generation system of  claim 5 , wherein the solar collector comprises an array of movable reflectors configured to concentrate the solar radiation at said zone. 
     
     
         7 . The electric power generation system of  claim 6 , wherein the concentrated solar radiation boosts the pressure and temperature of the steam to a supercritical level. 
     
     
         8 . The electric power generation system of  claim 7 , wherein the pressure is at least 3,750 psia and the temperature is at least 600° C. (1,112° F.). 
     
     
         9 . The electric power generation system of  claim 7 , wherein the zone at which the solar collector concentrates the solar radiation is along an exhaust path of a gas turbine in the flow path. 
     
     
         10 . The electric power generation system of  claim 9 , wherein the gas turbine produces a nominal exhaust flow at about 585 to 700° C. (1,000 to 1,200° F.) and the solar collector is configured to increase the temperature up to about 920° C. (1,600° F.) at maximum solar radiation. 
     
     
         11 . A gas turbine combined cycle apparatus comprising:
 a combustion turbine exhausting hot combustion gas products along a gas flow path to a heat recovery system having at least one steam generator   a main steam turbine coupled to an electric generator for generating electric power;   a gas heater coupled along the gas flow path, wherein the gas heater applies concentrated solar energy from a solar field to add heat to at least a portion of the hot combustion gas products from the combustion turbine.   
     
     
         12 . The gas turbine combined cycle apparatus of  claim 11 , wherein the heat recovery system comprises at least one once-through evaporator section configured to increase the energy of steam to supercritical conditions. 
     
     
         13 . The gas turbine combined cycle apparatus of  claim 12 , further comprising at least one additional evaporator section configured to increase the energy of the steam to a subcritical pressure levels. 
     
     
         14 . The gas turbine combined cycle apparatus of  claim 11 , comprising plural steam turbines operable to extract mechanical energy from steam at different temperature, pressure and flow conditions, and further comprising a controller and associated valves responsive to the controller, configured to route steam carrying available energy to selected ones of the plural steam turbines. 
     
     
         15 . The gas turbine combined cycle apparatus of  claim 14 , further comprising at least one controllable clutch responsive to the controller for selectively mechanically engaging and disengaging a shaft between the electric generator and at least one of the plural steam turbines. 
     
     
         16 . A heat transfer section configured to define a flow path in a power generation apparatus having at least one source of gaseous products and at least one energy extraction device producing useful work from the gaseous products, comprising:
 a conduit with inlet and outlet couplings configured to engage with the source and the energy extraction device;   wherein the conduit comprises a heat transfer section operable to receive and transfer incident solar radiation to gases flowing through the conduit;   a solar energy collector and concentrator system having reflectors arranged to direct solar radiation onto the heat transfer section.