Method for regulating a short-term power increase of a steam turbine

Abstract

A method for regulating a short-term power increase of a steam turbine with an upstream waste-heat steam generator is provided. The steam turbine has a number of economizer, evaporator and super heater heating surfaces forming a flow path for a flow medium. The flow medium is tapped off from the flow path in a pressure stage and is injected into the flow path on the flow-medium side between two super heater heating surfaces of the respective pressure stage. Amount of flow medium injected is regulated with a characteristic value which is a discrepancy between the outlet temperature of the final super heater heating surface and a predetermined temperature nominal value. The temperature nominal value is reduced and the characteristic value is temporarily increased more than in proportion to the discrepancy for a time period of the reduction for achieving a short-term power increase of the steam turbine.

1 .- 10 . (canceled) 
     
     
         11 . A method for regulating a short-term power increase of a steam turbine with an upstream waste heat steam generator, comprising:
 forming a flow path through which a flow medium flows by a plurality of economizer, evaporator and superheater heating surfaces of the waste heat steam generator;   branching off the flow medium in a pressure stage from the flow path;   injecting the flow medium into the flow path between two superheater heating surfaces of the pressure stage on a flow medium side;   regulating amount of the injected flow medium by a first characteristic value, wherein the first characteristic value is determined by a discrepancy between an outlet temperature of a superheater heating surface on the flow medium side of the pressure stage from a predetermined temperature nominal value;   reducing the temperature nominal value for the short-term power increase of the steam turbine; and   temporarily increasing the first characteristic value disproportionately to the discrepancy for a period of the reduction of the temperature nominal value.   
     
     
         12 . The method as claimed in  claim 11 , wherein the amount of the injected flow medium is further regulated by a temperature directly downstream from injection point of the flow medium. 
     
     
         13 . The method as claimed in  claim 11 , wherein the first characteristic value comprises a sum of the discrepancy and a second characteristic value, wherein the second characteristic value is a change over time of the temperature nominal value. 
     
     
         14 . The method as claimed in  claim 13 , wherein the second characteristic value is the change over time of the temperature nominal value multiplied by an amplification factor. 
     
     
         15 . The method as claimed in  claim 13 , wherein a parameter of the first or the second characteristic values is determined for a power plant. 
     
     
         16 . The method as claimed in  claim 11 , wherein the flow medium is injected into the flow path on the flow medium side downstream from the superheater heating surfaces, and wherein a time delay of the temperature nominal value is deactivated in determining the first characteristic value. 
     
     
         17 . The method as claimed in  claim 16 , wherein the time delay is characteristic for a throughflow time of the flow medium through the superheater heating surfaces between two injection points and/or thermal behavior of the superheater heating surfaces. 
     
     
         18 . A waste heat steam generator for a combined cycle power plant, comprising:
 a plurality of economizer, evaporator and superheater heating surfaces forming a flow path through which a flow medium flows; and   a regulation system adapted to perform the method as claimed in  claim 11 .   
     
     
         19 . A combined cycle power plant, comprising:
 a waste heat steam generator as claimed in  claim 18 .