Method for controlling fuel splits to gas turbine combustor

• US 7,593,803 B2
• Filed: 03/16/2007
• Issued: 09/22/2009
• Est. Priority Date: 11/20/2003
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Simons, Derrick Walter, Healy, Timothy Andrew
• Primary Examiner(s): Black; Thomas G
• Assistant Examiner(s): Behncke; Christine M
• Application Number:
  US11/687,196
• Publication Number:
  US 20070157620A1
• Time in Patent Office: 921 Days
• Field of Search: 701/104, 701/108, 701/99, 701/100, 606/86, 60/392.81, 607/72, 602/35, 60/395, 602/40, 607/90, 602/41, 602/43
• US Class Current: 701/100
• CPC Class Codes: F02C 9/28 Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed F02C9/30 - F02C9/38, F02C9/44 take precedence
• CPC Class Codes: F05D 2270/08 to produce clean exhaust gases
• CPC Class Codes: F05D 2270/112 by limiting temperatures
• CPC Class Codes: F05D 2270/303 Temperature
• CPC Class Codes: F23N 1/002 using electronic means F23N1/04 - F23N1/10 take precedence
• CPC Class Codes: F23N 2223/08 Microprocessor; Microcomputer
• CPC Class Codes: F23N 2225/06 for determining flow
• CPC Class Codes: F23N 2225/21 outlet temperature
• CPC Class Codes: F23N 2225/26 humidity
• CPC Class Codes: F23N 2241/20 Gas turbines
• CPC Class Codes: F23R 3/34 Feeding into different combustion zones

Abstract

A method for determining a target exhaust temperature for a gas turbine including: determining a target exhaust temperature based on a compressor pressure condition; determining a temperature adjustment to the target exhaust temperature based on at least one parameter of a group of parameters consisting of specific humidity, compressor inlet pressure loss and turbine exhaust back pressure; and adjusting the target exhaust temperature by applying the temperature adjustment.

Claims

1. A method for adjusting a base fuel split schedule for a gas turbine combustor comprising:

a. determining a corrected target turbine exhaust temperature based on a compressor pressure condition;

b. determining a first corrected temperature adjustment to the corrected target exhaust temperature based on at least one parameter of a group of parameters consisting of compressor inlet pressure loss and turbine exhaust back pressure;

c. determining a second corrected temperature adjustment to the corrected target exhaust temperature based on a nitrogen oxide (NOx) limiting requirement and the base fuel split command;

d. determining an adjusted corrected target exhaust temperature based on the first corrected temperature adjustment and the second corrected temperature adjustment;

e. determining an uncorrected adjusted target exhaust temperature based on a temperature of a discharge of a compressor of the gas turbine and the adjusted corrected target exhaust temperature;

f. determining a temperature difference between the uncorrected adjusted target exhaust temperature and an uncorrected target exhaust temperature selected from a combustor temperature leveling algorithm, and

g. applying the temperature difference to generate an adjusted fuel split schedule.

2. A method as in claim 1 wherein the uncorrected adjusted target exhaust temperature is further based on an uncorrected temperature adjustment determined from ambient specific humidity.

3. A method as in claim 1 wherein the difference between the uncorrected adjusted corrected target exhaust temperature and an uncorrected target exhaust temperature is limited to a positive value.

4. A method as in claim 1 wherein the adjusted fuel split schedule further comprises an adjusted first fuel split indicating a portion of fuel flow to a primary fuel nozzle in the combustor and an adjusted second fuel split indicating a portion of the fuel flow to be mixed with secondary air entering the combustor.

5. A method as in claim 1 wherein the base fuel split schedule is determined for a base load condition at which the gas turbine is operating at full rated power.

6. A method as in claim 1 wherein steps (b) through (g) are performed in connection with a nitrogen oxide (NOx) leveling algorithm.

7. A method as in claim 1 wherein the application of the difference further comprises:

deriving an adjusted projected NOx level from the temperature difference;

generating a Q factor as a ratio of a NOx emission baseline and the adjusted projected NOx level;

applying the Q factor to the base fuel split schedule to generate the adjusted fuel split schedule.

8. A method as in claim 7 further comprising determining the adjusted NOx level from a corrected value of the temperature difference.

9. A method as in claim 1 wherein each step of the method is performed automatically.

10. A method as in claim 1 wherein the fuel split level is a plurality of fuel split levels each indicating a portion of fuel flow to one of a plurality of zones of fuel nozzles in the combustor.

11. A method as in claim 1 wherein the fuel split schedule is a schedule for fuel splits to all combustors in the gas turbine.

20. A method as in claim 1 wherein the fuel split level is a plurality of fuel split levels each indicating a portion of fuel flow to one of a plurality of zones of fuel nozzles in the combustor.

12. A method for adjusting a base fuel split schedule for a gas turbine combustor comprising:

a. automatically determining a corrected target turbine exhaust temperature based on a compressor pressure condition;

b. automatically determining a first corrected temperature adjustment to the corrected target exhaust temperature based on at least one parameter of a group of parameters consisting of compressor inlet pressure loss and turbine exhaust back pressure;

c. automatically determining a second corrected temperature adjustment to the corrected target exhaust temperature based on a nitrogen oxide (NOx) limiting requirement and the base fuel split command;

d. automatically determining an adjusted corrected target exhaust temperature based on the first corrected temperature adjustment and the second corrected temperature adjustment;

e. automatically determining an uncorrected adjusted target exhaust temperature based on a temperature of a discharge of a compressor of the gas turbine and the adjusted corrected target exhaust temperature;

f. automatically determining a temperature difference between the uncorrected adjusted target exhaust temperature and an uncorrected target exhaust temperature selected from a combustor temperature leveling algorithm, and

g. automatically applying the temperature difference to generate an adjusted fuel split schedule.

13. A method as in claim 12 wherein the uncorrected adjusted target exhaust temperature is further based on an uncorrected temperature adjustment determined from ambient specific humidity.

14. A method as in claim 12 wherein the temperature difference between the uncorrected adjusted corrected target exhaust temperature and an uncorrected target exhaust temperature is limited to a positive value.

15. A method as in claim 12 wherein the adjusted fuel split schedule further comprises an adjusted first fuel split indicating a portion of fuel flow to a primary fuel nozzle in the combustor and an adjusted second fuel spit indicating a portion of the fuel flow to be mixed with secondary air entering the combustor.

16. A method as in claim 12 wherein the base fuel split schedule is determined for a base load condition at which the gas turbine is operating at full rated power.

17. A method as in claim 12 wherein steps (b) through (g) are performed in connection with a nitrogen oxide (NOx) leveling algorithm.

18. A method as in claim 12 wherein the application of the difference further comprises:

deriving an adjusted projected NOx level from the temperature difference;

generating a Q factor as a ratio of a NOx emission baseline and the adjusted projected NOx level;

applying the Q factor to the base fuel split schedule to generate the adjusted fuel split schedule.

19. A method as in claim 18 further comprising determining the adjusted NOx level from a corrected value of the temperature difference.