Method for switching over a gas turbine burner operation from liquid to gas fuel and vice-versa

Patent metadata

Field	Value
Publication number	US-9163560-B2
Application number	US-201213411797-A
Country	US
Kind code	B2
Filing date	Mar 5, 2012
Priority date	Sep 7, 2009
Publication date	Oct 20, 2015
Grant date	Oct 20, 2015

Abstract

A method is provided for switching over a gas turbine burner operation from liquid fuel to gas fuel and vice-versa, with the burner comprising nozzles for feeding a premixed gas fuel, nozzles for injecting a pilot gas fuel and nozzles for injecting a liquid fuel. According to the method, while the liquid fuel and the premix gas fuel are regulated to switch over from liquid fuel to gas fuel operation or vice-versa, the pilot gas fuel is controlled at a substantially constant flow rate.

First claim

What is claimed is:

1. Method for switching over a gas turbine burner operation from liquid fuel to gas fuel and vice-versa, said burner comprising nozzles for feeding a premixed gas fuel, nozzles for injecting a pilot gas fuel and nozzles for injecting a liquid fuel, the method comprising:
regulating the liquid fuel and the premix gas fuel to switch over from liquid fuel only operation to gas fuel only operation or vice-versa while controlling the pilot gas fuel at a substantially constant flow rate, wherein the regulating the liquid fuel and the premix gas fuel to switch over from liquid fuel only operation to gas fuel only operation or vice-versa while controlling the pilot gas fuel at a substantially constant flow rate comprises:
when switching over from gas fuel only operation to liquid fuel only operation:
increasing a water flow rate for injection of water into the burner, increasing a liquid fuel flow rate for feeding liquid fuel into the burner, decreasing a premix gas fuel flow rate for premix gas fuel to be fed into the burner and controlling a pilot gas fuel flow rate for pilot gas fuel to be fed into the burner such that the pilot gas fuel flow rate is controlled to be substantially constant while the liquid fuel and water flow rates are increased and the premix gas fuel flow rate is decreased to a minimum flow rate;
switching off the premix gas flow to the burner after the premix gas fuel flow rate is at the minimum flow rate; and
switching off the pilot gas fuel flow to the burner such that only liquid fuel is fed to the burner for liquid fuel only operation of the burner; and

when switching over from liquid fuel only operation to gas fuel only operation:
decreasing the water flow rate for injection of water into the burner, decreasing the liquid fuel flow rate for feeding liquid fuel into the burner, increasing the premix gas fuel flow rate for premix gas fuel to be fed into the burner and controlling the pilot gas fuel flow rate for pilot gas fuel to be fed into the burner such that the pilot gas fuel flow rate is controlled to be substantially constant while the liquid fuel and water flow rates are decreased and the premix gas fuel flow rate is increased; and
switching off the liquid fuel to the burner so that the only gas fuel is fed to the burner for gas fuel only operation of the burner.

2. The method as claimed in claim 1 , wherein the pilot gas fuel flow rate is controlled at a substantially constant flow rate to control the flame stability.

3. The method as claimed in claim 1 , wherein while the liquid fuel flow rate is regulated, water injection is regulated accordingly.

4. The method as claimed in claim 3 , wherein, when after regulation the premix gas fuel flow rate and/or the pilot gas fuel flow rate become zero, a purge medium is injected through premix gas fuel nozzles and/or pilot gas fuel nozzles.

5. The method as claimed in claim 3 , wherein, when after regulation the liquid fuel flow rate becomes zero, a purge medium is injected through the liquid fuel nozzles.

6. The method as claimed in claim 1 , wherein, before the pilot gas fuel is controlled at a substantially constant flow rate, the premix gas fuel and the pilot gas fuel and the liquid fuel are regulated together to bring the burner into starting switch over conditions.

7. The method as claimed in claim 1 , wherein, during the switch over, the gas turbine load is substantially constant.

8. The method as claimed in claim 1 , wherein, during switch over from gas fuel operation to liquid fuel operation, the operation temperature decreases and during switch over from liquid fuel operation to gas fuel operation, the operation temperature increases.

9. The method as claimed in claim 1 , wherein pilot gas fuel is injected through the pilot gas fuel nozzles at a side of a lance or at a tip of the lance or at a front panel.

10. The method as claimed in claim 1 , wherein liquid fuel is injected through the liquid fuel nozzles at a tip of a lance.

11. The method as claimed in claim 1 , wherein pilot gas is regulated before or after premix gas regulation.

12. The method as claimed in claim 11 , wherein during switching over from gas to liquid fuel operation, pilot gas fuel is regulated after premix gas fuel regulation to be switched off.

13. The method as claimed in claim 11 , wherein during switching over from liquid to gas fuel operation, pilot gas fuel is regulated before premix gas fuel regulation to be increased up to the operating flow rate.

14. The method as claimed in claim 1 , wherein the burner comprises at least two conical shells defining a substantially conical swirl chamber provided with tangential slots for feeding air and the nozzles for feeding the premix gas fuel therein, the nozzles for injecting the pilot gas fuel and a lance disposed centrally in the conical chamber and provided with the nozzles for injecting the liquid fuel.

15. The method of claim 1 , wherein, when switching over from gas fuel only operation to liquid fuel only operation:
injecting a purge medium into the nozzles for injecting the premix gas fuel into the burner after switching off the premix gas flow to the burner;
injecting a purge medium into the nozzles for injecting a pilot gas fuel after the switching off of the pilot gas fuel flow to the burner.

16. The method of claim 15 , wherein when switching over from liquid fuel only operation to gas fuel only operation:
injecting a purge medium into the nozzles for injecting the liquid fuel into the burner after switching off liquid fuel flow to the burner.

17. The method of claim 1 , wherein the premix gas fuel flow rate is further increased when the liquid fuel to the burner is switched off.

18. The method of claim 1 , comprising:
switching from liquid fuel only operation to gas fuel only operation; and
switching from gas fuel only operation to liquid fuel only operation.

Assignees

• Meeuwissen Thiemo
• Kokanovic Stanka
• Schell Susanne Renate
• Lachner Rudolf
• Alstom Technology Ltd

Inventors

• Meeuwissen Thiemo
• Kokanovic Stanka
• Schell Susanne Renate
• Lachner Rudolf

Classifications

• F02C3/24

  the fuel or oxidant being liquid at standard temperature and pressure · CPC title

• F23D17/002

  gaseous or liquid fuel · CPC title

• F23R3/286

  having fuel-air premixing devices (F23R3/30 takes precedence) · CPC title

• F23R3/343

  Pilot flames, i.e. fuel nozzles or injectors using only a very small proportion of the total fuel to insure continuous combustion (ignition in gas-turbine plants F02C7/264; pilot flame igniters F23Q9/00) · CPC title

• F02C3/22 Primary

  the fuel or oxidant being gaseous at standard temperature and pressure (F02C3/28 takes precedence) · CPC title