# US 8,539,750 B2 · Energy recovery and steam supply for power augmentation in a combined cycle power generation system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,539,750 B2 - Document ID: US8539750B2 - Status: Granted - Kind: B2 - Application number: 12/771,235 - Filed: 2010-04-30 - Published: 2011-11-03 - Granted: 2013-09-24 - Earliest claimed: 2010-04-30 - Assignees: Siemens Energy, Inc. - Applicants: James C. Bellows; Frederick W. Shoemaker - Inventors: James C. Bellows; Frederick W. Shoemaker - Web page: https://patentgrep.com/patent/US8539750B2 ## CPC - F01K 3/00: Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein (regenerating exhaust steam F01K19/00) - Y02E 20/16: Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT] - F01K: STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES (gas-turbine or jet-propulsion plants F02; nuclear power plants, engine arrangements therein G21D) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A power generation system (11) and method of operating such a system (11) including a steam turbine (14). In one embodiment a HRSG (20) includes an evaporator (127) coupled to receive condensate from the steam turbine (14), and a superheater (132) coupled to receive output from the evaporator (127). The HRSG (20) generates steam with thermal energy received from a combustion turbine (28). A flash tank (9) receives water heated in the HRSG (20), outputs a first portion of the water as steam, and outputs a second portion of the water as liquid. A flow line (134) passes steam (51) from the flash tank (9) to a combustion chamber (26) in the combustion turbine (28) to provide power augmentation. ## Claims ### Claim 1 A power generation system comprising: a steam turbine; a HRSG comprising (i) an evaporator coupled to receive condensate from the steam turbine, and (ii) a superheater coupled to receive output from the evaporator, the HRSG configured to generate steam for the steam turbine with thermal energy received from a combustion turbine; a flash tank positioned to (i) receive water heated in the HRSG, (ii) output a first portion of the received water as steam, and (iii) output a second portion of the received water as water; a flow line connected to pass the steam from the flash tank to a combustion chamber in a combustion turbine in order to selectively provide power augmentation; a water tank for receiving relatively cool replenishing water for input to the steam turbine system and thereby compensate for a deficincey in working fluid resulting from diversion of steam to the combustion chamber for power augmentation; and a heat exchanger coupled to receive the hot water from the flash tank and configured to receive and heat the relatively cool replenishing water from the water tank with the relatively hot liquid output from the flash tank, wherein the heat exchanger is coupled to provide the heated replenishing water to the steam turbine. ### Claim 2 (depends on 1) The power generation system of claim 1, further including a heat exchanger coupled to recover heat from the water output from the flash tank. ### Claim 3 (depends on 2) The power generation system of claim 2, wherein the heat exchanger is coupled to provide heated replenishing water to the steam turbine. ### Claim 4 (depends on 1) The power generation system of claim 1, wherein the condensate received from the steam turbine is heated in the HRSG. ### Claim 5 (depends on 1) The power generation system of claim 1, wherein the flash tank is connected to provide the steam as input to a combustion chamber of the combustion turbine. ### Claim 6 (depends on 1) The power generation system of claim 1 wherein the HRSG further includes a steam bottle positioned between the evaporator and the superheater to function as a moisture separation stage that provides the water, which is received by the flash tank, when wet steam is output from the evaporator, and wherein the steam bottle is connected to transfer the water to the flash tank. ### Claim 7 (depends on 1) The power generation system of claim 1 wherein the HRSG further includes a steam drum positioned between the evaporator and the superheater to function as a moisture separation stage that provides the water, which is received by the flash tank, when wet steam is output from the evaporator, and wherein the steam bottle is connected to transfer the water to the flash tank. ### Claim 8 (depends on 7) The power generation system of claim 7 wherein the steam drum effects entrainment of impurities, present in steam received from the evaporator, in the water received by the flash tank so that a portion of the impurities is transferred to the flash tank. ### Claim 9 A combined cycle power generation system comprising: a steam turbine; a combustion turbine including a compressor, a combustion chamber and a gas turbine; a HRSG comprising (i) an evaporator coupled to receive condensate from the steam turbine, and (ii) a superheater coupled to receive output from the evaporator, the HRSG configured to generate steam for the steam turbine with thermal energy received from the combustion turbine; a flash tank positioned to (i) receive water heated in the HRSG, (ii) output a first portion of the received water as steam input to the combustion chamber of the combustion turbine, and (iii) output a second portion of the water; a flow line connected to pass the steam from the flash tank to the combustion chamber of the combustion turbine in order to selectively provide power augmentation; a water tank for receiving relatively cool replenishing water for input to the steam turbine system and thereby compensate for a deficiency in working fluid resulting from diversion of steam to the combustion chamber for power augmentation; and a heat exchanger coupled to receive the water output from the flash tank and configured to receive and heat the relatively cool replenishing water from the water tank with the water output from the flash tank, wherein the heat exchanger is coupled to provide the heated replenishing water to the steam turbine. ### Claim 10 (depends on 9) The system of claim 9 wherein the flash tank is formed as part of the HRSG. ### Claim 11 A method of operating a combined cycle power generation system having a combustion turbine, a steam turbine system and a HRSG for transferring sensible heat from exhaust gases of the combustion turbine to the steam turbine system, comprising: separating moisture from a first supply of saturated steam produced at a relatively high pressure in the HRSG to provide a source of water; flashing a portion of the water in a flash tank to generate a second supply of steam at a lower pressure than the first supply of steam; selectively providing the second supply of steam to a combustion chamber of the gas turbine to provide power augmentation in the combined cycle power generation system; providing an unflashed portion of the water from the flash tank, as relatively hot liquid, to a heat exchange device to transfer heat present in the water to relatively cool make-up water and inputting make-up water to the steam turbine system to compensate for a deficiency in working fluid resulting from diversion of steam to the combustion chamber for power augmentation. ### Claim 12 (depends on 11) The method of claim 11 wherein the steps of separating moisture and flashing water are effected by positioning a steam drum to receive wet steam from an evaporator in the HRSG, forming the water in the steam drum and passing a portion of the water to a flash tank where a portion of the water remains as a liquid. ### Claim 13 (depends on 12) The method of claim 12 wherein the portion of the water in the flash tank which remains liquid after flashing is output to a heat exchanger for heat recovery. ### Claim 14 (depends on 13) The method of claim 13 wherein the liquid output from the flash tank to the heat exchanger is used to transfer sensible heat to a water supply used to replenish the power generation system to compensate for steam sent to the combustion chamber for power augmentation. ### Claim 15 (depends on 11) The method of claim 11 wherein the steps of separating moisture and flashing water are effected by positioning a steam bottle between an evaporator and a superheater in the HRSG to function as a moisture separation stage that generates the water and passing a portion of the water to a flash tank where a portion of the water remains as a liquid. ### Claim 16 (depends on 15) The method of claim 15 wherein the portion of the water in the flash tank which remains liquid after flashing is output to a heat exchanger for heat recovery. ### Claim 17 (depends on 16) The method of claim 16 wherein the liquid output from the flash tank to the heat exchanger is used to transfer sensible heat to a water supply used to replenish the power generation system to compensate for steam sent to the combustion chamber for power augmentation. ### Claim 18 (depends on 11) The method of claim 11 wherein, with the second supply of steam passed to the combustion chamber to provide power augmentation, a portion of the water formed by separating moisture from the first supply of saturated steam is recycled through an evaporator in the HRSG.