Combined cycle power system, and a method of operating a combined cycle power system

Abstract

A combined cycle power system includes a gas turbine exhausting an exhaust gas, a heat recovery steam generator including, a first economizer, a first steam generator, a second economizer, a second steam generator, a steam turbine which is driven by the steam generated at the first steam generator and the second steam generator, and a flasher which generates a first flash steam and a first drain water by flashing a portion of the water heated by the first economizer.

What is claimed is: 
     
         1 . A combined cycle power system, comprising:
 a gas turbine driven by a gas, and exhausting an exhaust gas,   a heat recovery steam generator including:
 a first economizer which heats water using waste heat of the exhaust gas from the gas turbine, 
 a first steam generator which generates steam from the water heated by the first economizer, 
 a second economizer which heats water, using waste heat of the exhaust gas prior to being supplied to the first economizer, 
 a second steam generator which generates steam from the water heated by the second economizer, 
   a steam turbine which is driven by the steam generated at the first steam generator and the second steam generator, and   a flasher which generates a first flash steam and a first drain water by flashing a portion of the water heated by the first economizer.   
     
     
         2 . The combined cycle power system of  claim 1 , wherein
 the first flasher supplies the first flash steam to the steam turbine.   
     
     
         3 . The combined cycle power system of  claim 1 , further comprising:
 a first flow line which supplies water to the first economizer, wherein the first flasher supplies the first drain water to the first flow line.   
     
     
         4 . The combined cycle power system of  claim 1 , further comprising:
 a first flow line which supplies water to the first economizer,   a second flow line which supplies water from the first economizer to the first flasher, and   a third flow line which supplies a portion of water flowing in the second flow line to the first flow line.   
     
     
         5 . The combined cycle power system of  claim 1 , further comprising:
 an auxiliary steam header which supplies an auxiliary steam to the steam turbine, wherein   the first flasher supplies the first flash steam to the auxiliary steam header.   
     
     
         6 . The combined cycle power system of  claim 5 , wherein
 the auxiliary steam header supplies the first flash steam as at least a portion of the auxiliary steam to the steam turbine.   
     
     
         7 . The combined cycle power system of  claim 5 ,
 the auxiliary steam header supplies a seal steam to an interspace portion of a turbine rotor and a casing of the steam turbine.   
     
     
         8 . The combined cycle power system of  claim 1 , further comprising:
 a second flasher which flashes the first drain water, and generates a second flash steam and a second drain water.   
     
     
         9 . The combined cycle power system of  claim 8 , wherein
 the second flasher supplies the second flash steam to the steam turbine.   
     
     
         10 . The combined cycle power system of  claim 8 , further comprising:
 a first flow line which supplies water to the first economizer, wherein   the second flasher supplies the second drain water to the first flow line.   
     
     
         11 . A method of operating a combined cycle power system, comprising:
 heating water using waste heat of a gas turbine at a first economizer,   generating steam from the water heated at the first economizer using a first steam generator,   heating water using waste heat of the exhaust gas at a second economizer prior to the waste heat being supplied to the first economizer,   generating steam from the water heated at the second economizer at a second steam generator,   driving a steam turbine using the steam from the first steam generator and the second steam generator,   generating a first flash steam and a first drain water by flashing a portion of the water heated by the first economizer using a first flasher, and   supplying the first flash steam to the steam turbine.   
     
     
         12 . The method of  claim 11 , comprising:
 supplying water to the first economizer using the first drain water generated by the first flasher.   
     
     
         13 . The method of  claim 11 , further comprising:
 the first economizer supplying heated water to the first flasher.   
     
     
         14 . The method of  claim 11 , further comprising:
 supplying an auxiliary steam to the steam turbine using a steam header, wherein the first flasher supplies the first flash steam to the auxiliary steam header.   
     
     
         15 . The method of  claim 14 , comprising:
 supplying a seal steam to the steam turbine using the steam header.   
     
     
         16 . The method of  claim 11 , further comprising:
 flashing the first drain water using a second flasher to generate a second flash steam and a second drain water.   
     
     
         17 . The method of  claim 16 , comprising:
 supplying the second flash steam to the steam turbine.   
     
     
         18 . The method of  claim 16 , comprising:
 supplying second drain water from the second flasher to the first economizer.