METHOD AND APPARATUS FOR MINIMIZING THERMOACOUSTIC VIBRATIONS IN GAS-TURBINE COMBUSTION CHAMBERS

• US 20010027638A1
• Filed: 09/10/1999
• Published: 10/11/2001
• Est. Priority Date: 09/10/1998
• Status: Active Grant

• Current Assignee: Alstom SA
• Original Assignee: Alstom SA
• Inventors: POLIFKE, WOLFGANG, GUTMARK, EPHRAIM, WEISENSTEIN, WOLFGANG, PASCHEREIT, CHRISTIAN OLIVER
• Granted Patent: US 6,840,046 B2
• Time in Patent Office: Days
• US Class Current: 60/776
• 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 2260/96 Preventing, counteracting or reducing vibration or noise
• CPC Class Codes: F05D 2270/14 to control thermoacoustic behaviour in the combustion chambers
• CPC Class Codes: F23R 2900/00013 Reducing thermo-acoustic vibrations by active means
• CPC Class Codes: F23R 2900/00014 Reducing thermo-acoustic vibrations by passive means, e.g. by Helmholtz resonators

Abstract

In a method of minimizing thermoacoustic vibrations in gas-turbine combustion chambers, a modulated spraying of liquid or gaseous premix fuel into a premix burner is carried out. The premix fuel is fed by means of two fuel lines (13, 14), and the modulation of the quantity of fed fuel is effected in each case by one fuel valve per fuel line.

Claims

1. A method of minimizing the pressure amplitude of thermoacoustic vibrations in a combustion system by modulated spraying of liquid or gaseous premix fuel, wherein the premix fuel is fed by means of two fuel lines (13, 14), and the modulation of the quantity of fed fuel is effected in each case by one fuel valve per fuel line.

2. The method as claimed in

claim 1

, the modulation being effected owing to the fact that, in addition to a constant quantity of premix fuel, fuel is additionally sprayed in the form of a pulse limited with respect to time, a complete modulation period consisting of the spraying of the pulse limited with respect to time and the subsequently absent addition of additional fuel.

3. The method as claimed in

claim 1

, the frequency of the modulation being between 0.3 Hz and 5 kHz, preferably between 5 Hz and 200 Hz.

4. The method as claimed in

claim 1

, the duty cycle being less than 100%, the condition 1%≦

(less than or equal to) duty cycle≦

(less than or equal to) 50% preferably being fulfilled.

5. The method as claimed in

claim 1

, the instantaneous spraying of liquid or gaseous premix fuel being phase-coupled with a signal measured in the combustion system.

6. The method as claimed in

claim 5

, in which the signal measured in the combustion system is filtered, phase-shifted and amplified, and the signal which is thus obtained controls fuel nozzles, which regulate the instantaneous spraying of liquid or gaseous premix fuel.

7. The method as claimed in

claim 5

or

6

, in which the signal measured in the combustion system is a pressure signal or a chemiluminescence signal, preferably a chemiluminescence signal from the emission of one of the radicals OH or CH.

8. The method as claimed in one of

claims 5

to

7

, in which the signal measured in the combustion system is measured in the combustion chamber or in a steadying chamber.

9. The method as claimed in

claim 1

, the modulation of the fed quantity of premix fuel in the two fuel lines being effected with any relative phase displacement φ

.

10. The method as claimed in

claim 9

, the modulation of the fed quantity of premix fuel in the two fuel lines being effected with a phase displacement φ

=0°

or with a phase displacement φ

=180°

.

11. An apparatus for controlling thermoacoustic vibrations in a combustion system having a burner, the burner having two fuel lines (13, 14) having openings (15) for the spraying of liquid or gaseous fuel, wherein one or more sensors for measuring thermoacoustic vibrations and means for controlling the instantaneous spraying of premix fuel as a function of the measuring signal of said sensors are arranged in the combustion system.

12. The apparatus as claimed in

claim 11

, in which the one or more sensors, arranged in the combustion system, for measuring thermoacoustic vibrations are pressure sensors, preferably microphones, in particular preferably water-cooled microphones.

13. The apparatus as claimed in

claim 11

, in which the one or more sensors, arranged, in the combustion system, for measuring thermoacoustic vibrations are optical sensors for visible or infrared radiation, preferably optical fiber probes.

14. The apparatus as claimed in

claim 11

, in which the means for controlling the instantaneous spraying of additional fuel comprise means for filtering, phase shifting and amplifying the measuring signal.