Inlet air heating system for a gas turbine engine

Abstract

A gas turbine engine has an inlet for delivering air into a compressor section. The compressor section is connected to feed air into a combustion section, wherein the air mixes with fuel and combusts. The combustion section is connected to turbine rotors such that products of combustion can pass over the turbine rotors to drive the turbine rotors. An exhaust communicates with the turbine sections to receive the products of combustion. A bleed tap communicates the exhaust to the inlet. A control controls the amount of exhaust gasses tapped into the inlet to achieve desired operating conditions.

1 . A gas turbine engine comprising:
 an inlet for delivering air into a compressor section;   the compressor section connected to feed air into a combustion section, wherein the air mixes with fuel and combusts, and the combustion section connected to a turbine section such that products of combustion can pass over a turbine rotor in the turbine section to drive the turbine rotor;   an exhaust for communicating with the turbine section to receive the products of combustion; and   a tap communicating said exhaust to said inlet, and a control for controlling an amount of exhaust gas tapped into the inlet to achieve desired operating conditions.   
   
   
       2 . The gas turbine engine as set forth in  claim 1 , wherein the amount of gas tapped from the exhaust to the inlet is controlled to achieve a desired inlet temperature at the inlet. 
   
   
       3 . The gas turbine engine as set forth in  claim 2 , wherein temperature sensors sense the temperature at the inlet and the exhaust and send signals to the control. 
   
   
       4 . The gas turbine engine as set forth in  claim 1 , wherein the control controls a blower to control the amount of exhaust gas passing from the exhaust to the inlet. 
   
   
       5 . The gas turbine engine as set forth in  claim 1 , wherein the control controls a damper to control the amount of exhaust gas passing from the exhaust to the inlet. 
   
   
       6 . The gas turbine engine as set forth in  claim 1 , wherein the turbine rotors drive a generator to create electricity. 
   
   
       7 . The gas turbine engine as set forth in  claim 1  wherein the combustion section is of a dry low NOx type. 
   
   
       8 . A method of operating a gas turbine engine comprising the steps of:
 (a) delivering air from an inlet to a compressor section;   (b) compressing air and delivering the air into a combustion section, mixing the compressed air with fuel and combusting the mixture, passing products of the combustion over turbine rotors to drive the turbine rotors;   (c) receiving the products of combustion at an exhaust; and   (d) tapping gas from said exhaust to said inlet, and controlling the amount of gas tapped to the inlet to achieve desired operating conditions in the gas turbine engine.   
   
   
       9 . The method as set forth in  claim 8 , wherein the amount of tapped gas is controlled to achieve a desired inlet temperature at the inlet; 
   
   
       10 . The method as set forth in  claim 8 , wherein the turbine rotors drive a generator to create electricity. 
   
   
       11 . A system for controlling the power provided by a gas turbine engine comprising:
 a tap line to tap exhaust gas from an exhaust of a gas turbine engine, and deliver the tapped exhaust gas to an inlet of the gas turbine engine; and   a control for controlling an amount of tapped exhaust gas that is delivered to the inlet of the gas turbine engine to achieve desired operating conditions.   
   
   
       12 . The system as set forth in  claim 11 , wherein the amount of gas tapped from the exhaust to the inlet is controlled to achieve a desired inlet temperature at the inlet. 
   
   
       13 . The system as set forth in  claim 12 , wherein temperature sensors sense the temperature at the inlet and the exhaust and send signals to the control. 
   
   
       14 . The system engine as set forth in  claim 11 , wherein the control controls a blower to control the amount of exhaust gas passing from the exhaust to the inlet. 
   
   
       15 . The system as set forth in  claim 11 , wherein the control controls a damper to control the amount of exhaust gas passing from the exhaust to the inlet.