Control device and control method for gas turbine engine

Abstract

A control device (CL) for a gas turbine (GT) according to the present disclosure comprises: a combustor (2) having a burner (15) that burns an air-fuel mixture (F) including a main fuel (F1) and at least one auxiliary fuel (F2) having a slower burning speed than that of the main fuel (F1); a fuel flow rate adjustment unit (50) that adjusts a flow rate of the air-fuel mixture (F) supplied to the burner (15); and a load disconnection signal reception unit (51) that receives a load disconnection signal when disconnecting a load from an external power system. The fuel flow rate adjustment unit (50) reduces the fuel supply to the burner (15) after maintaining the fuel supply for a predetermined time when the co-firing ratio, which is the volume flow rate ratio of the main fuel (F1) to the auxiliary fuel (F2), is less than a predetermined value and the load disconnection signal is received, and reduces the fuel supply to the burner (15) when the co-firing ratio is equal to or greater than the predetermined value and the load disconnection signal is received.

Description

Gas turbine engine control device and control method Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2024-026935, filed February 26, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a control system and method for a gas turbine engine.

[0003] In recent years, in order to reduce carbon dioxide emissions that cause environmental problems such as global warming and to realize a so-called low-carbon society, burner devices that use hydrogen as fuel have been proposed (for example, Patent Document 1).

[0004] Patent No. 7200077

[0005] Industrial gas turbines generate electricity while connected to an external power grid, but if there is an abnormality in the external power grid, it is necessary to turn off the grid breaker and instantly unload the gas turbine to maintain operation. When the grid breaker is turned off, the load is instantly removed and the gas turbine speed increases, so it is necessary to suddenly reduce the fuel supply to prevent the speed from exceeding the upper limit. This sudden reduction in fuel supply is performed using a governor (fuel control valve). The fuel is hydrogen gas or a mixture of city gas and hydrogen, but if the hydrogen combustion ratio is low, suddenly reducing the fuel supply when the load is removed may result in flame stabilization and a misfire or shutdown.

[0006] The disclosure of the present application has been made to solve the above-mentioned problems, and provides a gas turbine control device and control method that prevents the gas turbine rotation speed from exceeding an upper limit and prevents misfire and shutdown during load rejection.

[0007] A gas turbine control device according to one aspect of the present disclosure includes a combustor having a burner that burns an air-fuel mixture including a main fuel and at least one secondary fuel having a combustion speed slower than that of the main fuel, a fuel flow rate adjusting unit that adjusts the flow rate of the air-fuel mixture supplied to the burner, and a load shedding signal receiving unit that receives a load shedding signal during load shedding with an external power system, wherein the fuel flow rate adjusting unit reduces fuel supply to the burner after maintaining it for a predetermined time when a mixed-fuel ratio, which is a volumetric flow rate ratio of the main fuel to the secondary fuel, is less than a predetermined value and the load shedding signal is received, and reduces fuel supply to the burner when the mixed-fuel ratio is equal to or greater than the predetermined value and the load shedding signal is received.

[0008] According to a gas turbine control device according to one embodiment of the present disclosure, the fuel supply to the burner is maintained for a predetermined time and then reduced during load rejection, thereby making it possible to keep the gas turbine rotation speed below an upper limit and to prevent the gas turbine from misfire or stall.

[0009] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present disclosure. In particular, any combination of two or more of the claims is included in the present disclosure.

[0010] The present disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation, and should not be used to define the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same or corresponding parts.

[0023] Fig. 1 is a schematic diagram showing a gas turbine power generation system using a gas turbine control device according to the present disclosure. Fig. 2 is a partially cutaway perspective view showing a combustor according to the present disclosure. Fig. 3 is a longitudinal sectional view showing a combustor according to the present disclosure. Fig. 4 is a front view showing a burner used in the combustor of Fig. 2. Fig. 5 is a diagram showing load rejection data when hydrogen is mixed in the combustion chamber according to the present disclosure.

[0011] An embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a gas turbine power generation system in which a gas turbine GT control device CL according to an embodiment of the present disclosure is used. In the figure, the gas turbine GT includes, as main components, a compressor 1, a combustor 2, and a turbine 3. The combustor 2 includes a fuel supply device 5 and a fuel mixer 6 that mixes a main fuel F1 and a secondary fuel F2 supplied from the fuel supply device 5. Compressed air A supplied from the compressor 1 and a mixture F (F1 + F2) supplied from the fuel mixer 6 are combusted in the combustor 2, and high-temperature, high-pressure combustion gas G generated by the combustion is supplied to the turbine 3 to drive the turbine 3. Exhaust gas E is discharged from the turbine 3. The compressor 1 is driven by the turbine 3 via a rotary shaft 7, and the turbine 3 also drives a load 9, such as a generator, via a reduction gear 8. In the present disclosure, the term "mixture" refers to a mixture of multiple fuel gases, but air may also be mixed in.

[0012] In the following description, the main fuel F1 is hydrogen, the secondary fuel F2 is city gas, and the mixture F is a mixture of hydrogen F1 and city gas F2; ​​however, the fuels are not limited to these. The main fuel F1 may be any gas with a high combustion temperature and a fast combustion rate. Other examples of such fuels include ammonia. The secondary fuel F2 may be any hydrocarbon-based fuel containing 60% or more by volume of hydrocarbons.

[0013] In the following description, the compressor 1 side in the axial direction of the gas turbine GT will be referred to as the "upstream side" or "front side," and the turbine 3 side will be referred to as the "downstream side" or "rear side." Furthermore, in the following description, unless otherwise specified, the terms "axial direction," "radial direction," and "circumferential direction" refer to the axial direction, radial direction, and circumferential direction of the gas turbine GT, respectively.

[0014] FIG. 2 is a partially cutaway perspective view showing a combustor 2. This combustor 2 is a can-type combustor, with multiple combustors arranged annularly around the axis of the gas turbine GT. The combustor 2 includes a combustion liner 13 that defines a combustion chamber 11 therein, and a burner 15 attached to the top 13a of the combustion liner 13 and injecting fuel and air into the combustion chamber 11. A flame is formed in the combustion chamber 11 by igniting the fuel and air injected from the burner 15 with an ignition plug P provided in the combustion liner 13. The combustion liner 13 and the burner 15 are concentrically housed in a substantially cylindrical housing H, which serves as the outer casing of the combustor 2. An end cover 17 is fixed to the front end of the housing H with bolts 19. As shown in FIG. 3, a support liner 21 extending cylindrically from the combustion liner 13 is connected and fixed to the end cover 17 with bolts or the like, thereby attaching the top 13a of the combustion liner 13 to the housing H.

[0015] In this embodiment, the combustor 2 is configured as a counterflow type in which the compressed air A and the combustion gas G from the combustor 2 flow in opposite directions. That is, the combustor 2 has an air introduction passage 25 formed between the housing H and the combustion liner 13 and support liner 21. This air introduction passage 25 introduces the compressed air A compressed by the compressor 1 in a direction opposite to the flow direction of the combustion gas G in the combustion chamber 11. Note that the combustor 2 may be an axial flow type in which the compressed air A and the combustion gas G flow in the same direction. A plurality of air introduction holes 27 are arranged circumferentially at the front end of the peripheral wall of the support liner 21. The compressed air A sent through the air introduction passage 25 passes through the air introduction holes 27 and is introduced into an air supply passage 29 formed inside the support liner 21. The compressed air A introduced into the air supply passage 29 is sent rearward, i.e., toward the burner 15. Furthermore, a fuel supply header pipe 31 extending along the axis C of the combustor 2 is provided at the center of the air supply passage 29. The fuel mixture F is supplied from the fuel supply main pipe 31 to a fuel injection annular portion 33 of a fuel injection member 34, which will be described later. The configurations of the air supply passage 29 and the fuel supply main pipe 31 will be described in detail later.

[0016] As shown in FIG. 4 , the burner 15 includes a fuel injection member 34 having a plurality of fuel injection rings 33 and an air guide member 36 having a plurality of combustion air rings 35. In this embodiment, four fuel injection rings 33 having different diameters are arranged concentrically with one another and with the combustor 2. Also, five combustion air rings 35 having different diameters are arranged concentrically with one another and with the combustor 2. Furthermore, the fuel injection rings 33 and the combustion air rings 35 are arranged alternately with their respective central axes aligned. That is, the fuel injection rings 33 and the combustion air rings 35 are arranged concentrically and alternately. In this embodiment, the burner 15 includes four fuel injection rings 33 and five combustion air rings 35. However, these numbers can be changed as appropriate; for example, there may be three fuel injection rings 33 and four combustion air rings 35.

[0017] In this embodiment, the four fuel injection annular portions 33 and the five combustion air annular portions 35 are provided at the same axial position. However, the axial positions of the four fuel injection annular portions 33 and the five combustion air annular portions 35 may be offset from one another. For example, the four fuel injection annular portions 33 may be arranged so that their axial positions are offset from one another back and forth, or the five combustion air annular portions 35 may be arranged so that their axial positions are offset from one another back and forth to match the axial positions of the corresponding fuel injection annular portions 33.

[0018] As shown in FIG. 4 , in this embodiment, one combustion air annular portion 35 is disposed between two fuel injection annular portions 33, and air guide grooves 41 are provided on both the outer and inner diameter sides of this combustion air annular portion 35. Therefore, the burner 15 includes a fuel injection member 34 having four fuel injection annular portions 33 and an air guide member 36 having five combustion air annular portions 35. Specifically, the combustion air annular portion 35 is disposed on the outer periphery of the outermost fuel injection annular portion 33, three combustion air annular portions 35 are disposed between the four fuel injection annular portions 33, and another combustion air annular portion 35 is disposed on the inner periphery of the innermost fuel injection annular portion 33. The outer periphery of the outermost combustion air annular portion 35 of the air guide member 36 is covered by an annular support ring member 43. As shown in FIG. 2 , the support ring member 43 is connected to the combustion liner 13, thereby supporting the burner 15 in the combustion liner 13.

[0019] As shown in FIG. 2 , the air supply passage 29 is provided with an air rectifying plate 47 as an air rectifying mechanism that rectifies the compressed air A introduced into the air supply passage 29 from the air inlet hole 27 into a uniform flow toward the air guide member 36. The air rectifying plate 47 is a disc-shaped member having a plurality of through holes 49 extending therethrough in the axial direction. The air rectifying plate 47 has an outer diameter that matches the inner diameter of the support tube 21 shown in FIG. 3 and a fitting hole 51 in the center whose inner diameter matches the outer diameter of the fuel supply main pipe 31. In this embodiment, a cylindrical fitting portion 53 that fits onto the outer peripheral surface of the fuel supply main pipe 31 protrudes forward in the direction of the axis C from the fitting hole 51 of the air rectifying plate 47. The air rectifying plate 47 is connected and fixed to the end cover 17 with a flange 55 provided at the front end of the fitting portion 53 by a rectifying plate bolt 57.

[0020] In the illustrated example, the air rectifying plate 47 has a plurality of circular through holes 49 of the same diameter. More specifically, these plurality of through holes 49 are arranged in a state in which multiple rows of annular through holes 49 are arranged at equal intervals along the circumferential direction at the same radial position of the air rectifying plate 47, with the rows being equally spaced in the radial direction. In other words, the air rectifying plate 47 has rows of annular through holes 49 arranged at equal intervals on the same circumference, with multiple rows being provided with the same center. However, the shape, number, and arrangement of the plurality of through holes 49 in the air rectifying plate 47 are not limited to the above embodiment and may be set as appropriate.

[0021] As shown in FIG. 3 , the combustor 2 is provided with a flow straightening projection 63 located on its axis C, penetrating the burner 15 and projecting toward the combustion chamber 11. The flow straightening projection 63 is located within the air supply passage 29 and includes a cylindrical support portion 63a and a projection 63b located within the combustion chamber 11. In the illustrated example, the flow straightening projection 63 is attached to the burner 15, but it may also be attached to the fuel supply header pipe 31. In either case, the front end of the support portion 63a of the flow straightening projection 63 is located upstream of the burner 15. The tip of the projection 63b is formed in a substantially hemispherical shape. Although the flow straightening projection 63 may be omitted, providing the flow straightening projection 63 stably maintains a flame formed by fuel injected from the fuel injection annular portion 33 located radially inside the burner 15 and air supplied from the combustion air annular portion 35 near the axis C within the combustion chamber 11.

[0022] The fuel injection member 34, air guide member 36, support ring member 43 and straightening projection member 63 that constitute the burner 15 may be formed integrally, or may be formed separately and then connected to each other, for example, by inserting a pin radially therethrough.

[0023] Next, a fuel supply structure to the fuel injection member 34 in the combustor 2 will be described. The combustor 2 of this embodiment has multiple fuel supply passages that can independently supply the air-fuel mixture F to each fuel injection annular portion 33 of the fuel injection member 34. Specifically, the fuel supply header 31 and each fuel injection annular portion 33 are connected by multiple branch fuel supply pipes 66 that branch independently from one another. The fuel supply header 31 has a multi-pipe structure (double-pipe structure) in which multiple cylindrical pipes, i.e., an inner first fuel supply pipe 64 and an outer second fuel supply pipe 65, are concentrically stacked. The inner space of the first fuel supply pipe 64 forms a first fuel supply passage 67, and the space between the first fuel supply pipe 64 and the second fuel supply pipe 65 forms a second fuel supply passage 69. The air-fuel mixture F introduced from the outside into each fuel supply passage 67, 69 in the fuel supply main pipe 31 is supplied to each fuel injection annular portion 33 through the fuel supply passage formed in each branch fuel supply pipe 66.

[0024] In this embodiment, the air-fuel mixture F passing through the first fuel supply passage 67 is supplied to two fuel injection annular portions 33 located on the inner diameter side of the plurality of fuel injection annular portions 33 via two branch fuel supply pipes 66 connected to the first fuel supply pipe 64, and the air-fuel mixture F passing through the second fuel supply passage 69 is supplied to two fuel injection annular portions 33 located on the outer diameter side of the plurality of fuel injection annular portions 33 via two branch fuel supply pipes 66 connected to the second fuel supply pipe 65. An upstream portion 67a of the first fuel supply passage 67 extending outside the housing H, and an upstream portion 69a of the second fuel supply passage 69 extending outside the housing H are each provided with an adjustment valve 71 capable of adjusting the fuel flow rate. By adjusting the aperture of the adjustment valve 71 of each fuel supply passage 67, 69, the flow rate of the air-fuel mixture F supplied to each annular portion group of the fuel injection annular portions 33 can be independently controlled.

[0025] Next, a control method for the gas turbine GT configured as described above will be described. The gas turbine control device CL shown in FIG. 1 includes a fuel flow rate adjusting unit 50 that adjusts the flow rate of the mixture supplied to the burner 15 (FIG. 2) and a load shedding signal receiving unit 51 that receives a load shedding signal during load shedding from an external power system. As shown in FIG. 5, when the mixed-fuel ratio (hereinafter referred to as the "hydrogen mixed-fuel ratio"), which is the volumetric flow rate ratio of hydrogen F1 to city gas F2, is less than a predetermined value and a load shedding signal S is received from the load 9 shown in FIG. 1, the fuel flow rate adjusting unit 50 adjusts the control valve 71 to reduce the fuel supply to the burner 15 shown in FIG. 4 after a predetermined time T is maintained. The predetermined value of the mixed-fuel ratio refers to the minimum hydrogen mixed-fuel ratio at which flame stability is possible even when fuel is suddenly reduced during load shedding and the gas turbine GT does not misfire or shut down.

[0026] If the fuel supply to the burner 15 is maintained without being reduced when a load shedding signal S is received, the rotation speed of the gas turbine GT will reach its mechanical upper limit, causing the gas turbine GT to stop operating. Furthermore, if the hydrogen-mixed combustion ratio is below a predetermined value and the load shedding signal S is received and the governor included in the gas turbine control device CL suddenly reduces the fuel supply to the burner 15, the amount of hydrogen supplied will be insufficient to easily maintain flame stability, causing the gas turbine GT to misfire and shut down. According to the above configuration, when the hydrogen-mixed combustion ratio is below a predetermined value and a load shedding signal is received, the fuel supply to the burner 15 is maintained for the predetermined time T and then reduced. This keeps the rotation speed of the gas turbine GT below the upper limit and prevents the gas turbine GT from misfire and shutting down. By setting the predetermined time T to an extremely short time, an excessive increase in the rotation speed of the gas turbine GT is suppressed. Since the fuel supply to the burner 15 is then gradually reduced, the rotation speed of the gas turbine GT does not become excessive and returns to approximately the same level as before the load shedding.

[0027] Furthermore, when the hydrogen mixing ratio is equal to or greater than a predetermined value, flame stabilization is easy and there is no risk of the gas turbine GT misfire and shutting down, so when a load shedding signal is received, the fuel supply to the burner 15 is not maintained but is rapidly reduced, making it easy to keep the rotation speed of the gas turbine GT below the upper limit.

[0028] A plurality of fuel supply systems are connected to the burner 15 in Fig. 3, and the fuel flow rate adjusting unit 50 (Fig. 1) may reduce the fuel supply from at least one of the plurality of fuel supply systems after maintaining it for a predetermined time when the mixed-fuel ratio is below a predetermined value and a load shedding signal is received. In the configuration of the present disclosure, the plurality of fuel supply systems are the first fuel supply path 67 and the second fuel supply path 69, but three or more fuel supply paths may be provided. By maintaining the fuel supply from at least one of the plurality of fuel supply systems for a predetermined time T during load shedding and not supplying fuel from the other fuel supply systems, it is possible to suppress the rotation speed of the gas turbine GT to below an upper limit with the minimum necessary fuel supply and prevent the gas turbine GT from misfire or stall.

[0029] The burner 15 has a central burner 22, an inner burner 23, and an outer burner 24 arranged in an annular shape from the inside to the outside in the radial direction of the combustor 2, and the multiple fuel supply systems each have a first fuel flow rate supplied to the central burner 22 and a second fuel flow rate supplied to the inner burner 23 and the outer burner 24, and the fuel flow rate adjustment unit 50 adjusts the first fuel flow rate and the second fuel flow rate, and when the mixed combustion ratio is less than a predetermined value and a load shedding signal is received, may reduce the second fuel flow rate to the inner burner 23 and the outer burner 24, and may maintain the first fuel flow rate to the central burner 22 for a predetermined time, and reduce the first fuel flow rate after the predetermined time has elapsed.

[0030] In this embodiment, the central burner 22 is one of the two fuel injection annular portions 33 arranged on the inner diameter side of the plurality of fuel injection annular portions 33, and the air-fuel mixture F that has passed through the first fuel supply passage 67 is supplied from two branch fuel supply pipes 66 connected to the first fuel supply pipe 64. In other words, the first fuel flow rate is the fuel flow rate in the first fuel supply passage 67. The inner burner 23 is one of the two fuel injection annular portions 33 arranged on the outer diameter side of the plurality of fuel injection annular portions 33, and the outer burner 24 is one of the two fuel injection annular portions 33 arranged on the outer diameter side of the plurality of fuel injection annular portions 33. The air-fuel mixture F that has passed through the second fuel supply passage 69 is supplied to the inner burner 23 and the outer burner 24 from two branch fuel supply pipes 66 connected to the second fuel supply pipe 65. In other words, the second fuel flow rate is the fuel flow rate in the second fuel supply passage 69.

[0031] When load is rejected, fuel supply to the central burner 22, which is the main burner, is maintained for a predetermined time and then reduced after the predetermined time has elapsed. By simply controlling the governor of the central burner 22, the rotation speed of the gas turbine GT can be kept below the upper limit, and the gas turbine GT can be prevented from misfiring and stopping.

[0032] The present disclosure also includes the following control method for a gas turbine GT: The control method for a gas turbine GT includes a combustor 2 having a burner 15 that burns an air-fuel mixture containing a main fuel F1 and at least one secondary fuel F2 having a combustion speed slower than that of the main fuel F1, and a load shedding signal receiver 51 that receives a load shedding signal S during load shedding from an external power system, and reduces the fuel supply to the burner 15 after maintaining it for a predetermined time T when a mixed-fuel ratio, which is the volumetric flow rate ratio of the main fuel F1 to the secondary fuel F2, is less than a predetermined value and the load shedding signal S is received, and reduces the fuel supply to the burner 15 when the mixed-fuel ratio is equal to or greater than the predetermined value and the load shedding signal S is received.

[0033] When the hydrogen mixed combustion ratio is below a predetermined value and a load shedding signal S is received, the fuel supply to the burner 15 is maintained for a predetermined time T and then reduced, so the rotation speed of the gas turbine GT can be kept below the upper limit and the gas turbine GT can be prevented from misfire and shutting down. When the hydrogen mixed combustion ratio is above the predetermined value, flame stabilization is easy and there is no risk of the gas turbine GT shutting down due to misfire, so by not maintaining the fuel supply to the burner 15 but rapidly reducing it when the load shedding signal S is received, it is even easier to keep the rotation speed of the gas turbine GT below the upper limit.

[0034] A plurality of fuel supply systems are connected to the burner 15, and when the mixed combustion ratio is below a predetermined value and a load shedding signal S is received, the fuel supply from at least one of the plurality of fuel supply systems may be reduced after being maintained for a predetermined time T. By maintaining the fuel supply from at least one of the plurality of fuel supply systems for the predetermined time T during load shedding and not supplying fuel from the other fuel supply systems, it is possible to keep the rotation speed of the gas turbine GT below the upper limit with the minimum necessary fuel supply and to prevent the gas turbine GT from misfire or shut down.

[0035] As described above, the preferred embodiments of the present disclosure have been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present disclosure. Therefore, such additions, modifications, and deletions are also included in the scope of the present disclosure.

Claims

1. A gas turbine control device comprising: a combustor having a burner that burns a mixture containing a main fuel and at least one secondary fuel having a slower combustion speed than the main fuel; a fuel flow rate adjustment unit that adjusts the flow rate of the mixture supplied to the burner; and a load shedding signal receiving unit that receives a load shedding signal when load is shedding from an external power system, wherein the fuel flow rate adjustment unit reduces the fuel supply to the burner after maintaining it for a predetermined time when a mixed combustion ratio, which is the volumetric flow rate ratio of the main fuel to the secondary fuel, is less than a predetermined value and the load shedding signal is received, and reduces the fuel supply to the burner when the mixed combustion ratio is equal to or greater than the predetermined value and the load shedding signal is received.

2. A gas turbine control device according to claim 1, wherein a plurality of fuel supply systems are connected to the burner, and when the mixed combustion ratio is less than a predetermined value and the load shedding signal is received, the fuel flow rate adjusting unit reduces the fuel supply to at least one of the plurality of fuel supply systems after maintaining the fuel supply for the predetermined time.

3. A gas turbine control device according to claim 2, wherein the burners comprise, from the inside to the outside in the radial direction of the combustor, a central burner, an inner burner, and an outer burner; the plurality of fuel supply systems each have a first fuel flow rate supplied to the central burner and a second fuel flow rate supplied to the inner burner and the outer burner; the fuel flow rate adjustment unit adjusts the first fuel flow rate and the second fuel flow rate; and when the mixed combustion ratio is less than a predetermined value and the load shedding signal is received, the gas turbine control device reduces the second fuel flow rate and maintains the first fuel flow rate for the predetermined time, and reduces the first fuel flow rate after the predetermined time has elapsed.

4. A gas turbine equipped with the gas turbine control device according to claim 1 or 2.

5. A control method for a gas turbine comprising: a combustor having a burner that burns a mixture containing a main fuel and at least one secondary fuel having a combustion speed slower than that of the main fuel; and a load shedding signal receiving unit that receives a load shedding signal when load is shedding from an external power system, wherein when a mixed combustion ratio, which is the volumetric flow rate ratio of the main fuel to the secondary fuel, is less than a predetermined value and the load shedding signal is received, the fuel supply to the burner is maintained for a predetermined time and then reduced; and when the mixed combustion ratio is equal to or greater than the predetermined value and the load shedding signal is received, the fuel supply to the burner is reduced.

6. A gas turbine control method according to claim 5, wherein a plurality of fuel supply systems are connected to the burner, and when the mixed combustion ratio is less than a predetermined value and the load shedding signal is received, the fuel supply of at least one of the plurality of fuel supply systems is reduced after being maintained for the predetermined time.

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