Steam turbine cycle

Abstract

A steam turbine cycle of the present invention comprises a high pressure turbine 1 , a reheating turbine 24 , a boiler 4 , feed heaters 6 for heating a feed water to the boiler 4 by a bleed steam from the turbines 1 and 24 , a feed pump 12 , and a condenser 10 , the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle. A steam temperature at an outlet of the boiler is 590° C. or more. A temperature increase ratio between: a feed-water temperature increase in a first feed heater 7 corresponding to a bleed steam (high-pressure turbine exhaust bleed steam) 22 from an exhaust steam of the high pressure turbine 1 ; and an average of feed-water temperature increases in second feed heaters 8 where a pressure of the feed water is lower than that of the first feed heater 7 ; falls within 1.9-3.5.

1 . A steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
 wherein a steam temperature at an outlet of the boiler is 590° C. or more, and   a temperature increase ratio between: a feed-water temperature increase in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of feed-water temperature increases in second feed heaters where a pressure of the feed water is lower than that of the first feed heater; falls within 1.9-3.5.   
   
   
       2 . A steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
 wherein a steam temperature at an outlet of the boiler is 590° C. or more, and   a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of specific enthalpy increases in feed waters in second feed heaters where a pressure of the feed water is lower than that of the first feed heater; falls within 1.9-3.5.   
   
   
       3 . A steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
 wherein a steam temperature at an outlet of the boiler is 590° C. or more, and   a temperature increase ratio between: a feed-water temperature increase in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of feed-water temperature increases in feed heaters other than the first feed heater; falls within 1.9-3.5.   
   
   
       4 . A steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
 wherein a steam temperature at an outlet of the boiler is 590° C. or more, and   a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of specific enthalpy increases in feed heaters other than the first feed heater; falls within 1.9-3.5.   
   
   
       5 . The steam turbine cycle according to  claim 1 , wherein
 the feed-water temperature increases in the second feed heaters are calculated, in consideration of a temperature increase in the feed water by the feed pump.   
   
   
       6 . The steam turbine cycle according to  claim 2 , wherein
 the specific enthalpy increases in feed waters in the second feed heaters are calculated, in consideration of a specific enthalpy increase in the feed water by the feed pump.   
   
   
       7 . The steam turbine cycle according to  claim 1 , wherein
 the total number of the feed heaters is eight, and   the temperature increase ratio falls within 1.9-3.5.   
   
   
       8 . The steam turbine cycle according to  claim 2 , wherein
 the total number of the feed heaters is eight, and   the specific enthalpy increase ratio falls within 1.9-3.5.   
   
   
       9 . The steam turbine cycle according to  claim 1 , wherein
 the total number of the feed heaters is nine, and   the temperature increase ratio falls within 1.9-3.5.   
   
   
       10 . The steam turbine cycle according to  claim 2 , wherein
 the total number of the feed heaters is nine, and   the specific enthalpy increase ratio falls within 1.9-3.5.   
   
   
       11 . The steam turbine cycle according to  claim 1 , wherein
 a steam temperature at an outlet of the boiler is 600° C. or above.   
   
   
       12 . The steam turbine cycle according to  claim 3 , wherein
 the total number of the feed heaters is eight, and   the temperature increase ratio falls within 1.9-3.5.   
   
   
       13 . The steam turbine cycle according to  claim 4 , wherein
 the total number of the feed heaters is eight, and   the specific enthalpy increase ratio falls within 1.9-3.5.   
   
   
       14 . The steam turbine cycle according to  claim 3 , wherein
 the total number of the feed heaters is nine, and   the temperature increase ratio falls within 1.9-3.5.   
   
   
       15 . The steam turbine cycle according to  claim 4 , wherein
 the total number of the feed heaters is nine, and   the specific enthalpy increase ratio falls within 1.9-3.5.   
   
   
       16 . The steam turbine cycle according to  claim 2 , wherein
 a steam temperature at an outlet of the boiler is 600° C. or above.   
   
   
       17 . The steam turbine cycle according to  claim 3 , wherein
 a steam temperature at an outlet of the boiler is 600° C. or above.   
   
   
       18 . The steam turbine cycle according to  claim 4 , wherein
 a steam temperature at an outlet of the boiler is 600° C. or above.   
   
   
       19 . The steam turbine cycle according to  claim 3 , wherein
 the feed-water temperature increases in the other feed heaters are calculated, in consideration of a temperature increase in the feed water by the feed pump.   
   
   
       20 . The steam turbine cycle according to  claim 4 , wherein
 the specific enthalpy increases in feed waters in the other feed heaters are calculated, in consideration of a specific enthalpy increase in the feed water by the feed pump.