Systems and methods for determining a target exhaust temperature for a gas turbine

1. A method comprising:

determining a target exhaust temperature for a gas turbine engine comprising a compressor based at least in part on a compressor pressure condition;

determining a total flow rate comprising an air flow rate of the compressor and a steam flow rate of the compressor by multiplying a compressor discharge pressure by a constant;

determining the air flow rate by subtracting the steam flow rate from the total flow rate;

determining a water concentration by dividing the steam flow rate by the air flow rate;

determining a steam humidity by multiplying the water concentration by a calibration factor that is application specific;

determining a temperature adjustment to the target exhaust temperature based at least in part on the steam humidity;

changing the target exhaust temperature based at least in part on the temperature adjustment; and

applying the target exhaust temperature using a controller to set a fuel flow and/or air flow to a combustor of the gas turbine to achieve emissions requirements.

2. The method of claim 1 , wherein determining the temperature adjustment is further based on at least one of a CO or NOx emissions reference condition.

3. The method of claim 1 , wherein determining the temperature adjustment is further based at least in part on turbine ambient specific humidity.

4. The method of claim 1 , wherein determining the temperature adjustment is further based at least in part on delta inlet pressure loss, current compressor condition, and delta exhaust temperature output.

5. The method of claim 1 , wherein determining the temperature adjustment is further based at least in part on delta back pressure, current compressor condition, and delta exhaust temperature output.

6. The method of claim 1 , further comprising:

generating a plurality of target exhaust temperatures; and

selecting one of the plurality of target exhaust temperatures to facilitate control of the gas turbine engine.

7. The method of claim 1 , wherein the target exhaust temperature is applied by the controller to determine a turbine firing temperature.

8. The method of claim 1 , wherein the method is repeated periodically during operation of the gas turbine.

9. An apparatus, comprising:

a gas turbine engine;

a controller comprising a computer processor; and

a memory in communication with the computer processor storing computer-executable instructions operable to, when executed by the computer processor, cause the computer processor to:

determine a target exhaust temperature for a gas turbine engine comprising a compressor based at least in part on a compressor pressure condition;

determine a total flow rate comprising an air flow rate of the compressor and a steam flow rate of the compressor by multiplying a compressor discharge pressure by a constant;

determine the air flow rate by subtracting the steam flow rate from the total flow rate;

determine a water concentration by dividing the steam flow rate by the air flow rate;

determine a steam humidity by multiplying the water concentration by a calibration factor that is application specific;

determine a temperature adjustment to the target exhaust temperature based at least in part on the steam humidity;

change the target exhaust temperature based at least in part on the temperature adjustment; and

apply the target exhaust temperature using the controller to set a fuel flow and/or air flow to a combustor of the gas turbine engine to achieve emissions requirements.

10. The apparatus of claim 9 , wherein determining the temperature adjustment is further based on at least one of a CO or NOx emissions reference condition.

11. The apparatus of claim 9 , wherein determining the temperature adjustment is further based at least in part on turbine ambient specific humidity.

12. The apparatus of claim 9 , wherein determining the temperature adjustment is further based at least in part on delta inlet pressure loss, current compressor condition, and delta exhaust temperature output.

13. The apparatus of claim 9 , wherein determining the temperature adjustment is further based at least in part on delta back pressure, current compressor condition, and delta exhaust temperature output.

14. The apparatus of claim 9 , wherein the target exhaust temperature is applied by the controller to determine a turbine firing temperature.

15. The apparatus of claim 9 , wherein the computer-executable instructions are executed periodically during operation of the gas turbine engine.

16. A system, comprising:

a gas turbine engine comprising one or more compressors, one or more combustors, or one or more turbines;

a steam source for injecting steam into pre-combustion, post-compression air;

a controller comprising a computer processor; and

a memory in communication with the computer processor storing computer-executable instructions operable to, when executed by the computer processor, cause the computer processor to:

determine a target exhaust temperature based at least in part on a compressor pressure condition;

determine a total flow rate comprising an air flow rate of the compressor and a steam flow rate of the compressor by multiplying a compressor discharge pressure by a constant;

determine the air flow rate by subtracting the steam flow rate from the total flow rate;

determine a water concentration by dividing the steam flow rate by the air flow rate;

determine a steam humidity by multiplying the water concentration by a calibration factor that is application specific;

determine a temperature adjustment to the target exhaust temperature based at least in part on the steam humidity;

change the target exhaust temperature based at least in part on the temperature adjustment; and

apply the target exhaust temperature using the controller to set a fuel flow and/or air flow to a combustor of the gas turbine engine to achieve emissions requirements.

17. The system of claim 16 , wherein determining the temperature adjustment is further based on at least one of a CO or NOx emissions reference condition.