CONTROLLER AND METHOD

Abstract

A controller for a gas turbine arranged to supply a load is described. The gas turbine includes a fuel supply arranged to supply fuel at a fuel flow rate to a combustor. The fuel supply includes a first fuel supply and a second fuel supply. The controller is arranged to control a proportion of the fuel flow rate supplied via the first fuel supply based, at least in part, on the fuel flow rate. A gas turbine includes such a controller and a method controls such a gas turbine.

Claims

1. A method of controlling a gas turbine arranged to supply a load L, the gas turbine comprising a fuel supply means arranged to supply fuel at a fuel flow rate FF to a combustor, wherein the fuel supply means comprises a first fuel supply means and a second fuel supply means, the method comprising: controlling a proportion P of the fuel flow rate FF supplied via the first fuel supply means based, at least in part, on the fuel flow rate FF; measuring an ambient temperature TA and wherein the fuel flow rate FF is based, at least in part, on the ambient temperature TA, whereby a metal temperature and/or an emission is improved.

2. The method according to claim 1, wherein the controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply means is based, at least in part, on a reference fuel flow rate FFR.

3. The method according to claim 2, wherein the reference fuel flow rate FFR is at a first predetermined temperature T1, and/or a first predetermined load L1.

4. The method according to claim 1, wherein the controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply means is based, at least in part, on a reference proportion PR of the fuel flow rate FF supplied via the first fuel supply means.

5. The method according to claim 4, wherein the reference proportion PR of the fuel flow rate FF supplied via the first fuel supply means is at a second predetermined temperature T2, and/or a second predetermined load L2.

6. The method according to claim 4, wherein the proportion P of the fuel flow rate FF supplied via the first fuel supply means is determined by P=(FFR*PR)/FF.

7. The method according to claim 6, wherein the reference fuel flow rate FFR is at the first predetermined temperature T1 and/or the first predetermined load L1 and/or the reference proportion PR is at the second predetermined temperature T2 and/or the second predetermined load L2.

8. The method according to claim 1, comprising measuring a combustor exit temperature TX and/or a turbine inlet temperature TI and wherein the controlling the proportion P of the fuel flow rate F supplied via the first fuel supply means based, at least in part, on the fuel flow rate FF if the combustor exit temperature TX is greater than a third predetermined temperature T3 and/or if the turbine inlet temperature TI is greater than a fourth predetermined temperature T4.

9. The method according to claim 8, wherein the third predetermined temperature T3 is in a range from about 1400 K to 1900 K.

10. The method according to claim 8, wherein if the combustor exit temperature TX is at most the third predetermined temperature T3, the proportion P of the fuel flow rate FF supplied via the first fuel supply means is constant.

11. The method according to claim 1, wherein the first fuel supply means is a pilot fuel supply means.

12. The method according to claim 1, wherein the controlling the proportion P of the fuel flow rate FF supplied via the first fuel supply means is based, at least in part, on demanded kilowatts.

13. The method according to claim 1, wherein the gas turbine comprises a compressor, wherein the second predetermined temperature T2 is a gas temperature at the exit of the compressor.

14. The method according to claim 3, wherein the first predetermined temperature T1 is an ambient temperature.

15. The method according to claim 5, wherein the second predetermined temperature T2 is an ambient temperature.

16. A tangible non-transient computer-readable storage medium having recorded thereon instructions which when implemented by a controller for a gas turbine arranged to supply a load, the gas turbine comprising a fuel supply means arranged to supply fuel at a fuel flow rate FF to a combustor, wherein the fuel supply means comprises a first fuel supply means and a second fuel supply means, cause the controller to perform a method of controlling the gas turbine, the method according to claim 1.

17. The method according to claim 3, wherein the first predetermined temperature T1 is 323K, and the first predetermined load L1 is 100%.

18. The method according to claim 5, wherein the second predetermined temperature T2 is 323K, and the second predetermined load L2 is 100%.

19. The method according to claim 9, wherein the third predetermined temperature T3 is in a range from about 1500K to 1700K.

20. The method according to claim 9, wherein the third predetermined temperature T3 is in a range from about 1550K to 1650K.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0158] For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which:

[0159] FIG. 1 schematically depicts a longitudinal section of a typical gas turbine;

[0160] FIG. 2A schematically depicts a longitudinal section of a typical combustor and FIG. 2B schematically depicts a section along line III-III in FIG. 2A;

[0161] FIG. 3 schematically depicts a block diagram illustrating derivation of main and pilot fuel supplies in a typical gas turbine with multiple combustors;

[0162] FIG. 4 shows a graph of a Pilot Pressure Drop across a pilot nozzle as a function of ambient temperature for different loads L for a typical gas turbine, normalised for an ambient temperature of 50° C. and a load L of 80%;

[0163] FIG. 5 schematically depicts a controller for a gas turbine according to an exemplary embodiment;

[0164] FIG. 6 schematically depicts a gas turbine according to an exemplary embodiment;

[0165] FIG. 7 schematically depicts a method of controlling a gas turbine according to an exemplary embodiment; and

[0166] FIG. 8 shows a graph of a Pilot Pressure Drop across a pilot nozzle as a function of ambient temperature for different loads L for a typical gas turbine, normalised for an ambient temperature of 50° C. and a load L of 80%, according to an exemplary embodiment.

DETAILED DESCRIPTION

[0167] FIG. 5 schematically depicts a controller 50 for a gas turbine (not shown) according to an exemplary embodiment.

[0168] In more detail, the controller 50 is for a gas turbine arranged to supply a load L. The gas turbine comprises a fuel supply means arranged to supply fuel at a fuel flow rate FF to a combustor. The fuel supply means comprises a first fuel supply means and a second fuel supply means. The controller 50 is arranged to control a proportion P of the fuel flow rate FF supplied via the first fuel supply means based, at least in part, on the fuel flow rate FF.

[0169] The controller may be arranged as described previously.

[0170] FIG. 6 schematically depicts a gas turbine 600 according to an exemplary embodiment.

[0171] In more detail, the gas turbine 600 is arranged to supply a load L. The gas turbine 600 comprises a fuel supply means 60 arranged to supply fuel at a fuel flow rate FF to a combustor 70. The fuel supply means 60 comprises a first fuel supply means 61 and a second fuel supply means 62. The gas turbine 600 comprises the controller 50, as described above with reference to FIG. 5. Particularly, the controller 50 is arranged to control a proportion P of the fuel flow rate FF supplied via the first fuel supply means 61 based, at least in part, on the fuel flow rate FF.

[0172] FIG. 7 schematically depicts a method of controlling a gas turbine according to an exemplary embodiment.

[0173] In more detail, the method is of controlling a gas turbine arranged to supply a load L, the gas turbine comprising a fuel supply means arranged to supply fuel at a fuel flow rate FF to a combustor, wherein the fuel supply means comprises a first fuel supply means and a second fuel supply means.

[0174] At S701, a proportion P of the fuel flow rate FF supplied via the first fuel supply means is controlled based, at least in part, on the fuel flow rate FF, whereby a metal temperature and/or an emission is improved.

[0175] The method may include any of the steps described previously.

[0176] As described above, controlling the proportion P in this way may be applied, for example, as modifications to conventional pilot fuel control algorithms, to calculate and apply pilot split offsets for conventional pilot split maps for each load L and/or to split map envelopes, based, at least in part, on the fuel flow rate FF.

[0177] FIG. 8 shows a graph of a Pilot Pressure Drop across a pilot nozzle as a function of ambient temperature for different loads L for a typical gas turbine, normalised for an ambient temperature of 50° C. and a load L of 80%, according to an exemplary embodiment.

[0178] As shown in FIG. 8, for a load L of 100%, the pilot pressure drop is reduced to approximately by half for ambient temperatures from −20° C. to +50° C., which is the same value as at an ambient temperature of +50° C. With same pressure drop pilot fuel flow rate is also same which is shown as 1.16 unit across −20° C. to +50° C. For an ambient temperature of −30° C. and a load of 100%, the turbine inlet temperature TI is less than the fourth predetermined temperature T4 of about 1600 K and therefore, there is no change in the proportion P. Similarly, for loads L of 80% and 90%, the turbine inlet temperature TI is less than the fourth predetermined temperature T4 of about 1600 K and therefore, there is no change in the proportion P. In other words, the 100% load line is shifted such that fuel injector located at pilot where NOx is most sensitive receive lower fuel flow rate, thereby reducing tip temperature and/or NOx emissions.

[0179] Although an embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above.

[0180] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0181] All of the features disclosed in this specification (including any accompanying claims and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0182] Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0183] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.