Method for operating a burner arrangement of a gas turbine

Abstract

A method for operating a burner arrangement of a heat engine, particularly a gas turbine, having a plurality of burners, each having at least one pilot burner and main burner, in which method, on the basis of a preset operation of the heat engine, the total quantity of fuel supplied to the burners is maintained substantially constant in a load-controlled manner: in a first group of burners, for each burner, both the pilot burner as well as the main burner are supplied with fuel; in a second group of burners, the fuel supply to the main burners is interrupted, while the pilot burners continue to be operated; and the fuel quantity remaining as a result of the interruption of the fuel supply to the main burners of the second group is redistributed to the still active main burners of the first group. CO emissions are reduced as a result.

Claims

1. A method for operating a burner arrangement of a heat engine or of a gas turbine, having a plurality of burners, each comprising at least one pilot burner and at least one main burner, wherein, on the basis of a preset operation of the heat engine, in a load-controlled manner, the method comprising: maintaining a total quantity of fuel supplied to the burners substantially constant, in a first group of burners, in each burner, supplying both the pilot burner and the main burner with fuel, in a second group of burners, interrupting the fuel supply to the main burners, wherein the pilot burners continue to be operated, and redistributing the quantity of fuel remaining as a result of the interruption in the fuel supply to the main burners of the second group to the main burners of the first group which are still active.

2. The method as claimed in claim 1, further comprising: in a third group of burners, interrupting the fuel supply both to the main burners and to the pilot burners, and redistributing the remaining quantity of fuel to the main burners in the first group which are still active.

3. The method as claimed in claim 2, wherein a maximum of 30% of the burners are included in the third group.

4. The method as claimed in claim 1, wherein a maximum of 40% of the burners are included in the second group.

5. The method as claimed in claim 1, wherein the pilot burners of the burners in the second group are operated with a lower air ratio than the pilot burners in the first group.

6. The method as claimed in claim 1, wherein a number of burners with an at least partially interrupted fuel supply is varied, in accordance with the capacity of the heat engine.

7. The method as claimed in claim 1, wherein the main burners are operated in premix mode.

8. The method as claimed in claim 1, which is applied at a power output which lies below the rated capacity of the heat engine.

9. A combustion system for a heat engine, comprising: a burner arrangement having a plurality of burners, each of which comprises at least one pilot burner and at least one main burner, an auxiliary system for the supply of fuel to the burners, and a controller, which is configured to: maintain a total quantity of fuel supplied to the burners substantially constant, in a first group of burners, in each burner, supply both the pilot burner and the main burner with fuel, in a second group of burners, interrupt the fuel supply to the main burners, wherein the pilot burners continue to be operated, and redistribute the quantity of fuel remaining as a result of the interruption in the fuel supply to the main burners of the second group to the main burners of the first group which are still active.

10. The combustion system as claimed in claim 9, further comprising: a third group of burners, wherein, between a burner in the first group and a burner in the third group, at least one burner in the second group is arranged.

11. The combustion system as claimed in claim 10, further comprising: separate fuel lines to the pilot burners and main burners, wherein shut-off devices are at least installed in the fuel lines to the main burners in the second group and the third group.

12. The combustion system as claimed in claim 9, wherein the main burners are configured as premix burners.

13. The combustion system as claimed in claim 9, wherein the auxiliary system comprises a first subsystem and a second subsystem, wherein the first subsystem is designed for the supply of the main burners and the pilot burners in the first group, and the second subsystem is designed for the supply of the pilot burners in the second group.

14. The combustion system as claimed in claim 9, wherein the burner arrangement is configured as an annular combustion chamber.

15. A heat engine, comprising: a combustion system as claimed in claim 9.

16. The heat engine of claim 15, wherein the heat engine comprises a gas turbine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the invention are described hereinafter with reference to a drawing. Herein, in the individual figures:

(2) FIG. 1: shows a section of a burner, comprising a pilot burner and a main burner,

(3) FIG. 2: shows a schematic representation of an annular burner arrangement, having a first configuration of burners subdivided into two groups,

(4) FIG. 3: shows a schematic representation of the annular burner arrangement according to FIG. 1, having a second configuration of burners subdivided into three groups, and

(5) FIG. 4: shows an auxiliary system for the supply of fuel to a burner arrangement.

DETAILED DESCRIPTION OF INVENTION

(6) In the figures, identical reference symbols have the same meaning.

(7) FIG. 1 shows a burner 2 which, in combination with a plurality of identical burners, is employed, for example, in the combustion chamber 4 of a gas turbine installation which is not represented in greater detail.

(8) The burner 2 is comprised of an inner section, the pilot burner 6, and an outer section which is arranged concentrically thereto, the main burner system or main burner 8. Both the pilot burner 6 and the main burner 8 are suitable for operation with gaseous and/or liquid fuels, in any arbitrary combination.

(9) The pilot burner 6 comprises an inner gas infeed duct 14 (medium B), which is arranged concentrically about a duct 10. In turn, this is enclosed by an inner air infeed duct 12 (medium C), which is arranged concentrically about the axis of the burner 2. An appropriate ignition system can be arranged in or on the inner air infeed duct 12, many options for the embodiment of which are known, and the representation of which has therefore been omitted here.

(10) The pilot burner 6 can be operated in a manner which is known per se, i.e. predominantly as a diffusion burner. The function thereof is the maintenance of the stable combustion operation of the main burner 8, as the latter is generally operated with a lean mixture, in order to reduce pollutant emissions.

(11) FIG. 2 illustrates a burner arrangement 16 having a plurality of burners 2, and which particularly forms part of an annular combustion chamber of a gas turbine which is not represented in greater detail. The burner arrangement 16 comprises twenty-four burners 2. Twenty of the burners, which constitute a first group 18 (represented by filled-in circles), are operated as “hot” burners, i.e. in each burner 2, both the pilot burner 6 and the main burner 8 are supplied with fuel. The four other burners constitute a second group 20 (represented as a circle with a center point) of “warm” burners 2, in which the fuel supply to the main burners 8 is interrupted, wherein the pilot burners 6 continue to be operated. To this end, shut-off devices are incorporated into the lines to the main burners 8, which interrupt the infeed of fuel within a few seconds, for example in two seconds. The remaining quantity of fuel resulting from the interruption in the fuel supply to the main burners 8 in the second group 20 is redistributed to the still active main burners 8 in the first group 18. At the same time, an adjustment of the air ratio in the pilot burners 6 of the second group 20 can be undertaken, wherein a lower air ratio than that in the pilot burners 6 of the first group 18 is set.

(12) FIG. 3 illustrates the same burner arrangement 16, wherein the mode of operation of the burners 2 is different. Of the twenty-four burners 2, only eighteen are included in the first group 18, three are included in the second group 20, and three further burners constitute a third group 22 of “cold” burners (represented by a circle) which are completely isolated from the fuel supply, such that fuel is fed to neither the pilot burners 6 nor the main burners 8 of this group 22.

(13) Upon the transition from one configuration to the other, the total quantity of fuel delivered to the burner arrangement 16, in a load-controlled manner, remains constant at all times. For example, upon the transition from the standard operation of the annular combustion chamber, with “hot” burners only, to a configuration according to the invention with “warm” and, optionally, also “cold” burners 2, the total quantity of fuel does not generally change. In particular, operation with “warm” and “cold” burners 2 is executed at a gas turbine capacity below the rated capacity.

(14) Further configurations involving “hot”, “warm” and, optionally, “cold” burners 2 are also possible wherein, for example, the respective groups may be distributed over a number of locations. However, it is important that, in all cases, “hot” burners are screened from the “cold” burners 2 by “warm” burners 2, i.e. at least one burner 2 in the second group 20 is arranged between a burner 2 in the first group 18 and a burner 2 in the third group 22.

(15) FIG. 4 shows an exemplary representation of an auxiliary system 24 for the supply of fuel to a burner arrangement 16, wherein the auxiliary system 24 and the burner arrangement 16 constitute a combustion system 25. A central supply line 27 forms part of the auxiliary system 24. The burner arrangement 16 comprises e.g. twenty-four burners, which are subdivided into two groups 18, 20, which groups 18, 20 are symbolically represented in the figure by two burners 2.

(16) The burners 2 in the first burner group 18 are designed to be operated as “hot” burners, and the burners 2 in the second group 20 are designed to be operated as “warm” burners. In the embodiment represented, each of the burners 2 comprises a two-stage pilot burner, wherein the two stages are identified by the symbols P.sub.1, P.sub.2. Each of the burners 2 further comprises a two-stage main burner, the two stages of which are identified by the symbols M.sub.1, M.sub.2. However, other configurations of single- or multi-stage pilot and/or main burners are also conceivable.

(17) In the exemplary embodiment represented, the infeed of fuel to the two burner groups 18, 20 is delivered by means of separately controlled supplies, wherein the auxiliary system 24 is subdivided into two subsystems 26, 28.

(18) The first subsystem 26 comprises first lines 30 for the pilot burner stages P.sub.1, P.sub.2, and second lines 31 for the main burner stages M.sub.1, M.sub.2 of both burner groups 18, 20. The quantity of fuel in the first and second lines 30, 31 is adjusted by means of first control components 32 or second control components 34, wherein the control components 32, 34 are particularly configured as control valves. The lines 30, 31 respectively terminate in a ring line 36. From thence, by means of first spur lines 38, both pilot burner stages P.sub.1, P.sub.2 of all the pilot burners and, by means of second spur lines 40, both main burner stages M.sub.1, M.sub.2 of all the main burners are supplied. In the spur lines 38, 40 of the second burner group 20, moreover, shut-off valves 42 are installed. The first subsystem 26 is particularly intended for the supply of fuel to all the burners 2 of the burner arrangement 16 in on-site operation.

(19) The second subsystem 28 is similarly structured, and comprises third lines 44, in which control components 46 are installed, down-circuit ring lines 48 and further spur lines 50 to the pilot burner stages P.sub.1, P.sub.2 of the second group 20, wherein shut-off valves 52 are installed in the further spur lines 50.

(20) In standard operation, wherein both the pilot burners 6 and the main burners 8 of the burners 2 in both groups 18, 20 are operated, the shut-off valves 42 of the first subsystem 26 are open and the shut-off valves 52 of the second subsystem 28 are closed. Upon the switchover to “hot”/“warm” operation, all the shut-off valves 42 in the spur lines 38 and 40 of the second group 20 are closed, whereas the shut-off valves 52 are opened, as a result of which the pilot burners in the second group 20 are supplied with fuel by the second subsystem 28.

(21) As the shut-off valves 42 to the main burners in the second group 20 are closed, the fuel in the first subsystem 26 is redistributed to the main burners in the first group 18. A constant mass flow of fuel delivered to the pilot burners of the first group 18 is maintained. This is achieved, wherein the quantity of fuel delivered to the pilot burners of the first group 18 is throttled by the control valves 32, in order to compensate for the quantity of fuel which is no longer required for the pilot burners of the second group 20. The control valves 32 thus reduce the throughflow in the first lines 30 exactly by the quantity which is fed by the second subsystem 28 to the pilot burners in the second group 20. Further to the execution of the switchover, the quantity of fuel delivered to the pilot burners of the second group 20 is controllable independently of the quantity of fuel delivered to the pilot burners of the first group 18, and an optimum quantity setting is executed, according to the load. In total, the overall quantity of fuel in the auxiliary system 24 thus remains constant.

(22) By means of the second subsystem 28 illustrated, the burners 2 can be operated as burners in both the second group 20 and the third group 22, i.e. by means of the second subsystem 28, the infeed of fuel both to the main burners and to the pilot burners in this group can be interrupted.

(23) The controllable valves of the combustion system 25 are actuated by a controller 74, which is symbolically represented in FIG. 4. In particular, the controller 74 constitutes part of the combustion system 25.