Cooling Circuit for Enhancing Turbine Performance

Abstract

In a gas turbine having a compressor discharge casing, a cooling circuit diverts compressor discharge air toward a high pressure packing (HPP) circuit. The cooling circuit includes an inlet pipe that receives compressor discharge air. One or several cooled cooling air pipes are in fluid communication with the inlet pipe via a pipe manifold, which distributes the discharge air across the cooled cooling air pipes. A seal is disposed upstream of an entrance to the HPP circuit to limit flow into the HPP circuit, and a second seal is disposed downstream of the HPP circuit at turbine wheelspace to limit ingestion and thus the purge flow air required. The circuit serves to reduce required purge flow in the HPP circuit so that an amount of compressor discharge air can be put back to the main flow path, thereby improving turbine performance.

1 . A cooling circuit in a gas turbine for augmenting flow in a high pressure packing (HPP) circuit of the turbine, the cooling circuit comprising:
 an inlet pipe that receives compressor discharge air;   at least one cooled cooling air pipe in fluid communication with the inlet pipe via a pipe manifold, the pipe manifold distributing the discharge air across the at least one cooled cooling air pipe;   an upstream seal disposed upstream of an entrance to the HPP circuit; and   a downstream seal disposed downstream of the HPP circuit.   
   
   
       2 . A cooling circuit according to  claim 1 , further comprising a cooling source in communication with the at least one cooled cooling air pipe. 
   
   
       3 . A cooling circuit according to  claim 2 , wherein the cooling source comprises ambient air. 
   
   
       4 . A cooling circuit according to  claim 2 , wherein the cooling source comprises a heat exchanger. 
   
   
       5 . A cooling circuit according to  claim 2 , wherein the cooling source comprises an atomizer that sprays water droplets in contact with one of the diverted air and the at least one cooled cooling air pipe. 
   
   
       6 . A cooling circuit according to  claim 2 , wherein the cooling source comprises an ejector that mixes air from at least two compressor stages including the compressor discharge. 
   
   
       7 . A cooling circuit according to  claim 1 , wherein the cooled cooling air pipes penetrate a vertical flange of the compressor discharge casing and extend along a compressor discharge casing strut at trailing edges. 
   
   
       8 . A cooling circuit according to  claim 1 , further comprising a valve disposed between the inlet pipe and the cooled cooling air pipes, the valve adjusting mass flow and a temperature of the diverted air based on a temperature of the HPP circuit. 
   
   
       9 . A cooling circuit according to  claim 1 , further comprising openings in an inner barrel to permit cooled cooling air from the cooled cooling air pipes to reach at least one of a tie bolt and a marriage flange in the turbine. 
   
   
       10 . A cooling circuit according to  claim 1 , wherein the downstream seal comprises an abradable angel wing seal. 
   
   
       11 . A method of improving turbine performance using a cooling circuit by augmenting flow in a high pressure packing (HPP) circuit of the turbine, the method comprising:
 receiving compressor discharge air in an inlet pipe;   distributing the discharge air across a plurality of cooled cooling air pipes; and   disposing an upstream seal upstream of an entrance to the HPP circuit to regulate air entering the HPP circuit and disposing a downstream seal downstream of the HPP circuit to regulate a need for wheelspace purge air.   
   
   
       12 . A method according to  claim 11 , further comprising actively cooling the cooled cooling air pipes. 
   
   
       13 . A method according to  claim 12 , wherein the actively cooling step is practiced using ambient air. 
   
   
       14 . A method according to  claim 12 , wherein the actively cooling step is practiced using a heat exchanger. 
   
   
       15 . A method according to  claim 12 , wherein the actively cooling step is practiced using an atomizer that sprays water droplets in contact with one of the diverted air and the cooled cooling air pipes. 
   
   
       16 . A method according to  claim 12 , wherein the actively cooling step is practiced using an ejector that mixes air from at least two compressor stages. 
   
   
       17 . A method according to  claim 11 , wherein the discharge air is regulated by a valve. 
   
   
       18 . A cooling circuit in a gas turbine for augmenting flow in a high pressure packing (HPP) circuit of the turbine, the cooling circuit comprising:
 an inlet pipe that receives compressor discharge air;   at least one cooled cooling air pipe in fluid communication with the inlet pipe via a pipe manifold, the pipe manifold distributing the discharge air across the at least one cooled cooling air pipe;   a cooling source in direct contact with one of the at least one cooled cooling air pipe and the diverted air;   a valve disposed between the inlet pipe and the at least one cooled cooling air pipe, the valve adjusting mass flow and a temperature of the diverted air based on a temperature of the HPP circuit;   an upstream seal disposed upstream of an entrance to the HPP circuit; and   a downstream seal disposed downstream of the HPP circuit.