Steam turbine inlet temperature control system, computer program product and related methods

Abstract

Various embodiments include a system having: a computing device configured to control a power plant system including a steam turbine (ST), a gas turbine (GT), and a heat recovery steam generator (HRSG) fluidly connected with the ST and the GT, by performing actions including: obtaining data representing a target steam specific enthalpy in a bowl section of the ST; determining a current steam pressure at an outlet of the HRSG and a current steam temperature at the outlet of the HRSG; calculating an actual steam specific enthalpy in the bowl section of the ST based upon the current steam pressure at the outlet of the HRSG and the current steam temperature at the outlet the HRSG; and modifying a temperature of steam entering the ST in response to determining that the calculated actual steam specific enthalpy in the bowl section differs from the target steam specific enthalpy in the bowl section by a threshold.

We claim: 
     
         1 . A system comprising:
 at least one computing device configured to control a power plant system including a steam turbine (ST), a gas turbine (GT), and a heat recovery steam generator (HRSG) fluidly connected with the ST and the GT, by performing actions including:
 obtaining data representing a target steam specific enthalpy in a bowl section of the ST; 
 determining a current steam pressure at an outlet of the HRSG and a current steam temperature at the outlet of the HRSG; 
 calculating an actual steam specific enthalpy in the bowl section of the ST based upon the current steam pressure at the outlet of the HRSG and the current steam temperature at the outlet the HRSG; and 
 modifying a temperature of steam entering the ST in response to determining that the calculated actual steam specific enthalpy in the bowl section differs from the target steam specific enthalpy in the bowl section by a threshold. 
   
     
     
         2 . The system of  claim 1 , wherein the at least one computing device is configured to modify the temperature of the steam entering the ST by performing actions including modifying a temperature of exhaust gas from the GT entering the HRSG. 
     
     
         3 . The system of  claim 2 , wherein the modifying of the temperature of the exhaust gas from the GT includes modifying a firing temperature in the GT. 
     
     
         4 . The system of  claim 1 , wherein the calculating of the actual steam specific enthalpy includes measuring a pressure and a temperature of steam exiting the HRSG, and predicting an amount of expansion of the steam exiting the HRSG prior to entering the ST bowl. 
     
     
         5 . The system of  claim 1 , wherein the target steam specific enthalpy includes a model of an ideal steam specific enthalpy within the bowl section of the ST. 
     
     
         6 . The system of  claim 1 , wherein the threshold includes a range corresponding with a type of the ST. 
     
     
         7 . The system of  claim 1 , wherein the HRSG includes a set of HRSG devices including at least one terminal attemperator. 
     
     
         8 . A computer program product comprising program code, which when executed by at least one computing device, causes the at least one computing device to control a power plant system including a steam turbine (ST), a gas turbine (GT), and a heat recovery steam generator (HRSG) fluidly connected with the ST and the GT, by performing actions including:
 obtaining data representing a target steam specific enthalpy in a bowl section of the ST;   determining a current steam pressure at an outlet of the HRSG and a current steam temperature at the outlet of the HRSG;   calculating an actual steam specific enthalpy in the bowl section of the ST based upon the current steam pressure at the outlet of the HRSG and the current steam temperature at the outlet the HRSG; and   modifying a temperature of steam entering the ST in response to determining that the calculated actual steam specific enthalpy in the bowl section differs from the target steam specific enthalpy in the bowl section by a threshold.   
     
     
         9 . The computer program product of  claim 8 , wherein the program code causes the at least one computing device to modify the temperature of the steam entering the ST by performing actions including modifying a temperature of exhaust gas from the GT entering the HRSG. 
     
     
         10 . The computer program product of  claim 9 , wherein the modifying of the temperature of the exhaust gas from the GT includes modifying a firing temperature in the GT. 
     
     
         11 . The computer program product of  claim 8 , wherein the calculating of the actual steam specific enthalpy includes measuring a pressure and a temperature of steam exiting the HRSG, and predicting an amount of expansion of the steam exiting the HRSG prior to entering the ST bowl. 
     
     
         12 . The computer program product of  claim 8 , wherein the target steam specific enthalpy includes a model of an ideal steam specific enthalpy within the bowl section of the ST. 
     
     
         13 . The computer program product of  claim 8 , wherein the threshold includes a range corresponding with a type of the ST. 
     
     
         14 . The computer program product of  claim 8 , wherein the HRSG includes a set of HRSG devices including at least one terminal attemperator. 
     
     
         15 . A system comprising:
 a power plant system having: a gas turbine (GT); a heat recovery steam generator (HRSG) fluidly coupled with the GT; and a steam turbine (ST) fluidly coupled with the HRSG; and   at least one computing device configured to control the power plant system, by performing actions including:
 obtaining data representing a target steam specific enthalpy in a bowl section of the ST; 
 determining a current steam pressure at an outlet of the HRSG and a current steam temperature at the outlet of the HRSG; 
 calculating an actual steam specific enthalpy in the bowl section of the ST based upon the current steam pressure at the outlet of the HRSG and the current steam temperature at the outlet the HRSG; and 
 modifying a temperature of steam entering the ST in response to determining that the calculated actual steam specific enthalpy in the bowl section differs from the target steam specific enthalpy in the bowl section by a threshold. 
   
     
     
         16 . The system of  claim 1 , wherein the at least one computing device is configured to modify the temperature of the steam entering the ST by performing actions including modifying a temperature of exhaust gas from the GT entering the HRSG. 
     
     
         17 . The system of  claim 16 , wherein the modifying of the temperature of the exhaust gas from the GT includes modifying a firing temperature in the GT. 
     
     
         18 . The system of  claim 15 , wherein the calculating of the actual steam specific enthalpy includes measuring a pressure and a temperature of steam exiting the HRSG, and predicting an amount of expansion of the steam exiting the HRSG prior to entering the ST bowl. 
     
     
         19 . The system of  claim 15 , wherein the target steam specific enthalpy includes a model of an ideal steam specific enthalpy within the bowl section of the ST. 
     
     
         20 . The system of  claim 15 , wherein the threshold includes a range corresponding with a type of the ST.