Controller, gas turbine and controlling method

Abstract

To provide a controller capable of improving stability during operation under load.SOLUTION: A controller controls a gas turbine comprising: a compressor; a combustor to which compressed air output from the compressor and fuel from a fuel flow path are supplied; and a turbine rotated by combustion gas generated by the combustor. The controller controls the gas turbine so that a fuel flow rate does not fall below a predetermined first minimum value that is larger than a flow rate at full speed and no load when the gas turbine is operating under load.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a control device, a gas turbine, and a control method.

Background Art

[0002] Patent Document 1 discloses the following valve control device. That is, in the feedback control of the gas turbine speed, when the load of the gas turbine is reduced, the valve control device disclosed in Patent Document 1 controls the minimum value of the valve opening degree of the fuel control valve to a value from a first opening degree to a second opening degree larger than the first opening degree, thereby preventing overshoot and undershoot of the gas turbine speed. Note that the second opening degree is smaller than the opening degree indicated by the CLCSO (combustion load command value) in the no-load operation.

[0003] Further, Patent Document 2 discloses a gas turbine including a pilot nozzle provided in a combustor, the pilot nozzle including a premixed pilot nozzle and a diffusion pilot nozzle. According to the gas turbine disclosed in Patent Document 2, by switching the combustion mode of the pilot combustion from the diffusion combustion mode to the premixed combustion mode in accordance with the gas turbine startup to the rated operation, the generation amount of nitrogen oxides (NOx) in the load operation can be suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in the valve control device disclosed in Patent Document 1, the second opening degree is smaller than the opening degree indicated by CLCSO during no-load operation. Therefore, according to the valve control device disclosed in Patent Document 1, for example, when there is a reduction in load such that the valve opening degree must be further reduced from the first opening degree to the second opening degree, which are valve opening degrees smaller than the valve opening degree during no-load operation, overshoot and undershoot of the rotational speed of the gas turbine can be prevented.

[0006] On the other hand, although the premixed combustion method disclosed in Patent Document 2 can achieve low NOx, it has the characteristic that the combustion temperature for maintaining the flame is higher than that of the diffusion combustion method. For this reason, when a load reduction occurs, for example, if the valve opening degree is set smaller than the valve opening degree during no-load operation, there is a risk of misfire (extinction of the flame), and there is a problem that the stability during load operation may decrease.

[0007] The present disclosure has been made to solve the above problems, and an object thereof is to provide a control device, a gas turbine, and a control method capable of improving the stability during load operation.

Means for Solving the Problems

[0008] In order to solve the above problems, a control device according to the present disclosure is a control device that controls a gas turbine including a compressor, a combustor to which compressed air output from the compressor and fuel from a fuel flow path are supplied, and a turbine rotated by combustion gas generated in the combustor, and controls the gas turbine so that the flow rate of the fuel does not fall below a predetermined first minimum value that is greater than that at full speed no-load during load operation of the gas turbine.

[0009] The gas turbine according to the present disclosure includes a compressor, a combustor supplied with compressed air output from the compressor and fuel from a fuel flow path, a turbine rotated by combustion gas generated in the combustor, and a control device that controls the flow rate of the fuel. The control device controls the gas turbine so that the flow rate of the fuel does not fall below a predetermined first minimum value that is greater than that at full speed and no load during the load operation of the gas turbine.

[0010] The control method according to the present disclosure is a control method for controlling a gas turbine including a compressor, a combustor supplied with compressed air output from the compressor and fuel from a fuel flow path, and a turbine rotated by combustion gas generated in the combustor. During the load operation of the gas turbine, the gas turbine is controlled so that the flow rate of the fuel does not fall below a predetermined first minimum value that is greater than that at full speed and no load.

Advantages of the Invention

[0011] According to the control device, gas turbine, and control method of the present disclosure, the stability during load operation can be improved.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0013] Hereinafter, a control device, a gas turbine, and a control method according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 10. In each figure, the same or corresponding components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0014] FIG. 1 is an overall configuration diagram of a gas turbine plant 100 according to an embodiment of the present disclosure. The gas turbine plant 100 includes a gas turbine 112 and a generator 114.

[0015] The gas turbine 112 includes a compressor 120, a combustor 122, and a turbine 124. The compressor 120 is driven by a rotating shaft 126 to compress the air taken in from an air intake port to generate compressed air. The combustor 122 injects fuel into the compressed air introduced from the compressor 120 into a combustion chamber 128 to generate high-temperature and high-pressure combustion gas. That is, the combustor 122 is supplied with the compressed air output from the compressor 120 and the fuel 4 from a fuel flow path 171. The turbine 124 is rotationally driven by the combustion gas generated in the combustor 122. That is, the turbine 124 is rotated by the combustion gas generated in the combustor 122.

[0016] A bypass pipe 130 is provided between the passenger compartment 128 and the combustor 122. When the air in the combustor 122 becomes insufficient due to the load fluctuation of the gas turbine 112, the bypass pipe 130 becomes a flow path for introducing the air in the passenger compartment 128 into the combustor 122 when the combustor bypass valve 132 is opened. Also, an extraction pipe 134 for introducing cooling air from the compressor 120 to the turbine 124 is provided between the compressor 120 and the turbine 124.

[0017] Note that the turbine 124, the compressor 120, and the generator 114 are connected by a rotating shaft 126, and the rotational driving force generated in the turbine 124 is transmitted to the compressor 120 and the generator 114 by the rotating shaft 126. Then, the generator 114 generates electricity by the rotational driving force of the turbine 124 and supplies the generated electric power to the power grid.

[0018] Also, a nozzle 136 is provided in the combustor 122. Fuel whose flow rate is adjusted by a fuel control valve 142 is supplied to the nozzle 136. Then, the combustor 122 burns the fuel supplied from the nozzle 136 using compressed air. In this embodiment, the nozzle 136 includes a main combustion nozzle 7, a premixed pilot nozzle 10, and a diffusion pilot nozzle 11, which will be described later. Also, the fuel control valve 142 includes a plurality of fuel control valves that independently control the flow rates of the fuel supplied to the main combustion nozzle 7, the premixed pilot nozzle 10, and the diffusion pilot nozzle 11.

[0019] The opening degree of the fuel control valve 142 is controlled by a valve control device 144. The valve control device 144 is an example of a configuration of the "control device" according to the present disclosure, and controls the gas turbine 112 so that the fuel flow rate does not fall below a predetermined minimum value during the load operation of the gas turbine 112. For example, when the load of the gas turbine 112 decreases and the rotational speed of the turbine 124 (hereinafter referred to as "turbine rotational speed") increases, the valve control device 144 reduces the opening degree of the fuel control valve 142 (hereinafter referred to as "valve opening degree") to reduce the fuel flow rate supplied to the combustor 122. In the present embodiment, the load operation is the operation of the gas turbine 112 with the generator 114 connected in parallel to the power grid, and includes, for example, governor operation. The governor operation is an operation in which the opening degree of the fuel control valve 142 is changed to keep the frequency of the power grid constant and the load fluctuation is absorbed.

[0020] FIG. 2 shows an enlarged cross-sectional view of the main part of the combustor 122 according to the present embodiment, and FIG. 3 shows a plan view of the combustor 122 as viewed from the side where the pilot mixed gas is injected.

[0021] As shown in FIG. 2, the pilot combustion burner 1 is disposed at the center of the above-described combustor 122, and a plurality of main combustion burners 6 are disposed along the circumferential direction so as to surround the pilot combustion burner 1 on the inner peripheral surface of the combustor 122.

[0022] Also, a pilot fuel line (not shown) is connected to the fuel flow paths 62 and 63 of the pilot combustion burner, and a main combustion line (not shown) is connected to the fuel flow path 15 of each main combustion nozzle 7.

[0023] Therefore, the high-temperature and high-pressure compressed air 3 flows into the combustor 122. Inside this combustor 122, this compressed air 3 is mixed with the fuel 4 injected from the main combustion burner 6, forms a swirling flow of the premixed gas, and flows into the combustor tail pipe 48. Further, the compressed air 3 is mixed with the fuel 4 injected from the pilot combustion burner 1, is ignited by a kindling not shown in the figure and burns, and becomes combustion gas and jets into the combustor tail pipe 48. At this time, a part of the combustion gas jets out into the surroundings with a flame in the combustor tail pipe 48, so that the premixed gas flowing into the combustor tail pipe 48 from the main combustion burner 6 is ignited and burns. That is, the flame from the pilot fuel injected from the pilot combustion burner 1 can perform flame holding for stable combustion of the lean premixed fuel from the main combustion burner 6. Further, a flame holder 12 is arranged at the end of the pilot combustion burner 1. As shown in FIG. 2, a region called a re-circulation zone (recirculation region) is generated downstream of this flame holder 12. In this recirculation region, the high-temperature burned gas of the main combustion burner 6 performs a swirling motion such that it flows backward near the central axis, which helps to constantly ignite the lean premixed fuel of the main combustion burner 6.

[0024] As shown in FIG. 2, the pilot combustion burner 1 has a diffusion pilot nozzle 11 arranged at its center, and a premixed pilot nozzle 10 is arranged so as to surround the diffusion pilot nozzle 11. The fuel flow path 62 for supplying fuel to the premixed pilot nozzle 10 and the fuel flow path 63 for supplying the fuel 4 to the diffusion pilot nozzle 11 are each independent systems, and the fuel flow rates can be changed separately.

[0025] The fuel injection port 16 of the premixed pilot nozzle 10 and the fuel injection port 17 of the diffusion pilot nozzle 11 are provided in the flame holder 12 portion. The flame holder 12 is disk-shaped when viewed from the side where the pilot mixed gas is injected, but has a trapezoidal cross-sectional shape when viewed from the side direction, and its radius increases as it advances in the fuel injection direction. Further, the end face position of the flame holder 12 on the pilot mixed gas injection port side is substantially at the same position as the outlet portion of the extension pipe 13 of the main combustion burner 6 when viewed in a direction perpendicular to the straight line passing through the central axis of the combustor 122.

[0026] In the above-described configuration, the diffusion pilot nozzle 11 ejects the fuel 4 from a plurality of fuel injection ports 17 penetrating the flame holder 12 with a predetermined diameter, mixes with the surrounding compressed air 3, and performs diffusion combustion in the combustor 122. It is desirable that the fuel injection port 17 of the diffusion pilot nozzle 11 be able to discharge fuel toward the outer side in the radial direction of the flame holder 12. Therefore, it is preferably penetrated along the radial direction of the flame holder 12, and the straight line penetrating the flame holder 12 vertically and the fuel injection direction have a predetermined inclination angle so that the fuel injection direction becomes the outer edge direction of the flame holder 12. By doing so, the fuel 4 can be ejected to the outer side in the radial direction, so that the combustion gas from the diffusion pilot nozzle reaches the outlet of the extension pipe 13 of the main combustion burner located in the outer peripheral direction of the flame holder 12, and the flame holding property of the lean premixed fuel from the main combustion burner is increased and the combustion becomes stable.

[0027] On the other hand, the premixed pilot nozzle 10 is composed of a plurality of holes 14 penetrating the flame holder 12 with a predetermined diameter and the fuel injection port 16 of the premixed pilot nozzle 10 provided at a position where a gap of a predetermined dimension is provided from these holes 14. The fuel 4 ejected from the fuel injection port 16 mixes with the compressed air 3, is discharged as a pilot mixed gas from the holes 14, and burns in the combustor 122.

[0028] As shown in FIG. 3, the premixed pilot nozzle 10 penetrates a plurality of holes 14 (8 in the figure) in the circumferential direction at a predetermined radial position of the flame holder 12 inside a plurality of main combustion burners 6 (8 in the figure in the figure), and the fuel injection port 16 of the premixed nozzle is provided at the center position of the hole and on the upstream side with respect to fuel injection.

[0029] At this time, in order to prevent each main combustion nozzle 7 from being on the extension of the straight line connecting the center of the flame holder 12 and the center of each hole 14, the circumferential position of the hole 14 is shifted from the circumferential position of the main combustion nozzle 7 and arranged. Note that it is preferable that the circumferential interval of the holes 14 is constant. On the other hand, although the fuel injection port 17 of the diffusion pilot nozzle 11 is also provided at a predetermined radial position of the flame holder 12, it is desirable to arrange the fuel injection port 17 of the diffusion pilot nozzle 11 so that the center position of the main combustion nozzle 7 is on the extension of the straight line connecting its center and the center of the flame holder 12. As described above, since the premixed pilot nozzles 10 are arranged at regular intervals in the circumferential direction, the pilot mixed gas ejected from the premixed pilot nozzles 10 will have breaks in the circumferential direction. The combustion gas ejected from the main combustion burner 6 circulates in the burner tail pipe 48 to form a circulating flow of high-temperature burned gas. This circulating flow of high-temperature burned gas passes between the pilot mixed gas ejected from the premixed pilot nozzles 10 and reaches the outlet of the extension pipe 13 of the main combustion burner 6. Since the flame retention property of the lean premixed fuel from the main combustion burner 6 is enhanced and the combustion becomes stable, combustion vibration can be suppressed.

[0030] In FIG. 3, the number of fuel injection ports of the premixed pilot nozzles 10 and the diffusion pilot nozzles 11 is the same as that of the main combustion burner 6, but the number can be appropriately changed. Also, in FIG. 3, the fuel injection port 17 of the diffusion nozzle is shown as a circle for simplicity, but the actual shape is an ellipse with a major axis in the fuel ejection direction.

[0031] FIG. 4 is a functional block diagram showing the functional configuration of the valve control device 144 according to the present embodiment. The valve control device 144 includes a GVCSO calculation unit 150, a MINCSO calculation unit 54, a selection unit 156, and a valve control unit 170.

[0032]

[0033] ​In the governor operation, the GVCSO calculation unit 150 outputs a control command value (hereinafter referred to as "GVCSO") for changing the valve opening degree according to the fuel flow rate for making the turbine rotation speed coincide with a target value (hereinafter referred to as "rotation speed target value").

[0034] Specifically, the GVCSO calculation unit 150 includes a subtraction unit 160 and a multiplication unit 162. The subtraction unit 160 receives the rotation speed target value of the turbine rotation speed and the turbine rotation speed, and subtracts the turbine rotation speed from the rotation speed target value. The multiplication unit 162 multiplies the subtraction value output from the subtraction unit 160 by a proportional gain, and outputs the multiplication result as GVCSO. In this way, the GVCSO calculation unit 150 calculates GVCSO by feedback. Note that when GVCSO increases, the valve opening degree also increases, and when GVCSO decreases, the valve opening degree also decreases.

[0035] The MINCSO calculation unit 154 is configured as shown in FIG. 5, for example. The MINCSO calculation unit 154 shown in FIG. 5 receives the intake air temperature T1C (201) of the gas turbine 112, calculates MICSO1 (204) corresponding to the "first minimum value" of the present disclosure, and selects one of MINCSO1 (204) and MINCSO2 (206) corresponding to the "second minimum value" of the present disclosure, and outputs it as MINCSO (208). MINCSO1 (204) is a control command value corresponding to the minimum fuel flow rate during the load operation, and MINCSO2 (206) is a control command value corresponding to the minimum fuel flow rate during the load cut-off. During the load operation, the fuel flow rate is controlled so as not to be lower than the fuel flow rate corresponding to MINCSO1, and during the load cut-off, the fuel flow rate is controlled so as not to be lower than the fuel flow rate corresponding to MINCSO2.

[0036] As shown in FIG. 6, for each fuel flow rate corresponding to the stop of the gas turbine 112, full speed no load (rated rotation no load), and full load (rated load), MINCSO1 is set to a value greater than the fuel flow rate at full speed no load (rated rotation no load), and MINCSO2 is set to a value less than the fuel flow rate at full speed no load. The predetermined value of the change in the usage state is a value corresponding to the fuel flow rate that serves as a reference when changing the usage states of the premixed pilot nozzle 10 and the diffusion pilot nozzle 11. The predetermined value of the change in the usage state corresponds to the "predetermined value" of the present disclosure. In the steady state during the load operation, when it is equal to or greater than the predetermined value of the change in the usage state, the premixed pilot nozzle 10 is used and the diffusion pilot nozzle 11 is not used. When it is less than the predetermined value of the change in the usage state, the premixed pilot nozzle 10 is not used and the diffusion pilot nozzle 11 is used. The predetermined value of the change in the usage state is greater than MINCSO1. Note that "not used" may include both the case of complete non - use (when the fuel control valve 142 is fully closed) and the case of almost non - use (when the fuel control valve 142 is more open than fully closed).

[0037] The calculation of MINCSO1 (204) is as follows. First, using a function (202) that obtains the relationship between the intake temperature (201) of the compressor 120 and the output (or load) (MW) of the gas turbine 112, the output (MW) corresponding to the minimum combustion temperature that can maintain the flame by fuel injection from the premixed pilot nozzle 10 is calculated based on the intake temperature (T1C). Next, using a function (203) that obtains the relationship between the output of the gas turbine 112 and the fuel supplied to the combustor 122, the output (MW) calculated by the function (202) is converted into a control command value (CSO) corresponding to the fuel flow rate. In this way, MINCSO1 (204) is set based on the load corresponding to the minimum combustion temperature that can maintain the flame by fuel injection from the premixed pilot nozzle 10.

[0038] On the other hand, MINCSO2 (206) is set so that, for example, misfires, undershoots, overshoots, etc. do not occur during load interruption, and can be calculated using, for example, the calculation method described in Patent Document 1.

[0039] When the control signal SW is "ON", the switch (205) selects MINCSO1 (204), and when the control signal SW is "OFF", the switch (205) selects MINCSO2 (206) and outputs it as the control signal MINCSO (208). That is, MINCSO (208) is either the control command value MINCSO1 corresponding to the minimum value of the fuel flow rate during load operation or the control command value MINCSO2 corresponding to the minimum value of the fuel flow rate during load interruption. Further, the control signal SW turns ON when the operating load is greater than or equal to (the predetermined value of the change in the usage state or more), and turns OFF when the operating load is less than (the predetermined value of the change in the usage state or less) or under a predetermined condition. The predetermined condition is satisfied, for example, when the gas turbine 112 is disconnected (during load interruption), during in-house independent operation, during automatic stop, when the stop operation of the gas turbine 112 is performed, etc., and the control signal SW becomes "OFF".

[0040] Returning to FIG. 4, the selection unit 156 selects the control command value corresponding to the larger fuel flow rate from among the GVCSO output from the GVCSO calculation unit 150 and the MINCSO output from the MINCSO calculation unit 154, and outputs it to the valve control unit 170 as the control command value CSO. The value of the control command value CSO corresponds to the total fuel amount flowing into the combustor 122.

[0041] As shown in FIG. 6, the valve control unit 170 sets the usage states of the premixed pilot nozzle 10 and the diffusion pilot nozzle 11 based on the predetermined value of the change in the usage state, or sets the fuel ratios to the main combustion nozzle 7, the premixed pilot nozzle 10, and the diffusion pilot nozzle 11 by a known method, and generates and outputs a control signal to the fuel control valve 142.

[0042] With the above configuration, the valve control device 144 controls the gas turbine 112 including the compressor 120, the combustor 122 supplied with the compressed air output from the compressor 120 and the fuel from the fuel flow path 171, and the turbine 124 rotated by the combustion gas generated in the combustor 122. When the gas turbine 112 is under load operation, the valve control device 144 controls the gas turbine 112 so that the fuel flow rate does not fall below the MINCSO1 (first minimum value) which is greater than that at full speed no load. Further, the combustor 122 includes the premixed pilot nozzle 10 and the diffusion pilot nozzle 11 capable of independently controlling the fuel injection amount, and the valve control device 144 changes the usage states of the premixed pilot nozzle 10 and the diffusion pilot nozzle 11 based on a predetermined change value (predetermined value) of the fuel flow rate usage state which is greater than the MINCSO1 (first minimum value). Further, when the load of the gas turbine 112 is cut off, the valve control device 144 sets the MINCSO2 (second minimum value) which is smaller than that at full speed no load with respect to the fuel flow rate, and controls the gas turbine 112 so that the fuel flow rate does not fall below the MINCSO2. Note that the MINCSO1 is calculated from the relationship between the intake air temperature T1C of the compressor 120 and the output MW of the gas turbine 112, and the relationship between the output MW of the gas turbine 112 and the fuel (CSO) supplied to the combustor 122. Further, the MINCSO1 is set based on the load (MW) corresponding to the minimum combustion temperature at which the flame can be maintained by the fuel injection from the premixed pilot nozzle 10.

[0043] Next, with reference to FIGS. 7 to 9, an operation example of the gas turbine 112 according to the present embodiment will be described. FIG. 7 is a timing chart showing an operation example (at startup) of the gas turbine according to the embodiment of the present disclosure. FIG. 8 is a timing chart showing an operation example (during load fluctuation) of the gas turbine according to the embodiment of the present disclosure. FIG. 9 is a timing chart showing an operation example (during load cut-off) of the gas turbine according to the embodiment of the present disclosure. FIGS. 7 to 9 show the time on the horizontal axis, and on the vertical axis show the change in the fuel flow rate (control command value CSO), the change in the usage state of the premixed pilot nozzle 10, and the change in the usage state of the diffusion pilot nozzle 11. Note that the valve closed corresponds to the non-use in FIG. 6, and the control state corresponds to the use in FIG. 6.

[0044] In the example shown in FIG. 7, the operation of the gas turbine 112 starts at time t10 and reaches the full load state at time t14. At time t10, the premixed pilot nozzle 10 is valve-closed and the diffusion pilot nozzle 11 is in a controlled state. At time t11, the fuel flow rate reaches a predetermined value of the change in the usage state, the valve opening control (control for shifting to the controlled state) is started for the premixed pilot nozzle 10, and the valve closing control (control for shifting to valve closing) is started for the diffusion pilot nozzle 11. Then, at time t12 when a time T20 has elapsed from time t11, the premixed pilot nozzle 10 becomes in a controlled state, and at time t13, the diffusion pilot nozzle 11 is valve-closed.

[0045] In the example shown in FIG. 8, a load fluctuation occurs at time t21 in the full load state and the fuel flow rate is reduced from the full load. The state before time t21 is that the premixed pilot nozzle 10 is in a controlled state and the diffusion pilot nozzle 11 is valve-closed. At time t22, the fuel flow rate becomes smaller than the predetermined value of the change in the usage state, the valve closing control is started for the premixed pilot nozzle 10, and the valve opening control is started for the diffusion pilot nozzle 11. At time t23, the fuel flow rate becomes equal to or less than MINCSO1, and the fuel flow rate is held at MINCSO1. At time t24, the diffusion pilot nozzle 11 becomes in a controlled state and the reduction of the fuel flow rate is restarted. When the fuel flow rate drops to the fuel flow rate corresponding to the load fluctuation at time t25, the fuel flow rate becomes constant at that value. Also, at time t26, the premixed pilot nozzle 10 is valve-closed.

[0046] Note that FIG. 8 shows, by a broken line, the change in the fuel flow rate when the control of the minimum value during the load operation by MINSCO1 is not performed (in the case without restrictions). In this case, the fuel flow rate drops to the fuel flow rate corresponding to the load fluctuation. Therefore, for example, at time ta1 when the state where the fuel flow rate has dropped to the fuel flow rate corresponding to the load fluctuation continues for a time Ta, for example, misfire may occur. On the other hand, in the present embodiment, since the lower limit value by MINSCO1 is set for the fuel flow rate during the load operation using the premixed pilot nozzle 10, the occurrence of misfire can be prevented.

[0047] In the example shown in FIG. 9, load shedding occurs at time t31 in the full load state, and the fuel flow rate is reduced from the full load. The state before time t31 is that the premixed pilot nozzle 10 is in the control state and the diffusion pilot nozzle 11 is valve-closed. At time t31, at the timing of load shedding, valve-closed control is started for the premixed pilot nozzle 10, and valve-opening control is started for the diffusion pilot nozzle 11. At time t32, the fuel flow rate is equal to or less than MINCSO1, but since MINCSO is set to MINCSO2, the fuel flow rate decreases below MINCSO1. At time t33, the fuel flow rate becomes equal to or less than MINCSO2, and the fuel flow rate is held at MINCSO2. At time t34, the diffusion pilot nozzle 11 becomes the control state, and an increase in the fuel flow rate is started. At time t35, the premixed pilot nozzle 10 is valve-closed at time t26. At time t36, when the fuel flow rate increases to the fuel flow rate corresponding to full speed no load, the fuel flow rate becomes constant at that value.

[0048] (Function and effect) In the valve control device 144 (control device), gas turbine 112, and control method having the above configuration, during the load operation of the gas turbine 112, the gas turbine 112 is controlled so that the fuel flow rate does not fall below MINCSO1 (a predetermined first minimum value), which is greater than that at full speed no load. Therefore, according to the valve control device 144 (control device), gas turbine 112, and control method of the present embodiment, the stability during load operation can be improved.

[0049] (Other embodiments) As described above, the embodiments of the present disclosure have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present disclosure are also included.

[0050] 〈Computer configuration〉 FIG. 10 is a schematic block diagram showing the configuration of a computer according to an embodiment of the present disclosure. The computer 90 includes a processor 91, a main memory 92, a storage 93, and an interface 94. The above valve control device 144 is implemented in the computer 90. And the operations of the above-described respective processing units are stored in the storage 93 in the form of a program. The processor 91 reads the program from the storage 93, expands it in the main memory 92, and executes the above processing according to the program. Also, the processor 91 secures a storage area corresponding to each of the above-described storage units in the main memory 92 according to the program.

[0051] The program may be for realizing a part of the functions to be exhibited by the computer 90. For example, the program may exhibit functions by combination with other programs already stored in the storage or by combination with other programs implemented in other devices. In other embodiments, the computer may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), FPGA (Field Programmable Gate Array), and the like. In this case, part or all of the functions realized by the processor may be realized by the integrated circuit.

[0052] Examples of the storage 93 include HDD (Hard Disk Drive), SSD (Solid State Drive), magnetic disk, magneto-optical disk, CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), semiconductor memory, and the like. The storage 93 may be an internal medium directly connected to the bus of the computer 90, or may be an external medium connected to the computer 90 via the interface 94 or a communication line. Further, when this program is distributed to the computer 90 via a communication line, the computer 90 that has received the distribution may expand the program in the main memory 92 and execute the above processing. In at least one embodiment, the storage 93 is a non-transitory tangible storage medium.

[0053] <Appendix> The valve control device 144 (control device) described in each embodiment is understood as follows, for example.

[0054] (1) The valve control device 144 (control device) according to the first aspect is a control device that controls a gas turbine including a compressor, a combustor to which compressed air output from the compressor and fuel from a fuel flow path are supplied, and a turbine rotated by combustion gas generated in the combustor, and controls the gas turbine so that the flow rate of the fuel does not fall below a predetermined first minimum value that is greater than that at full speed and no load during the load operation of the gas turbine. According to this aspect and the following aspects, the stability during load operation can be improved.

[0055] (2) The valve control device 144 (control device) according to the second aspect is the valve control device 144 in (1), wherein the combustor includes a premixed pilot nozzle and a diffusion pilot nozzle capable of independently controlling the injection amount of the fuel, and based on a predetermined value of the fuel flow rate greater than the first minimum value, the usage states of the premixed pilot nozzle and the diffusion pilot nozzle are changed. According to this aspect, the stability of the operation using the premixed pilot nozzle can be improved. Also, low NOx can be achieved.

[0056] (3) The valve control device 144 (control device) according to the third aspect is the valve control device 144 in (1) or (2), and when the load of the gas turbine is cut off, a second minimum value smaller than that at full speed no load is set for the fuel flow rate, and the gas turbine is controlled so that the fuel flow rate does not fall below the second minimum value. According to this aspect, the stability of the operation at the time of load cut-off can be improved.

[0057] (4) The valve control device 144 (control device) according to the fourth aspect is the valve control device 144 in (1) to (3), and the first minimum value is calculated from the relationship between the intake temperature of the compressor and the output of the gas turbine and the relationship between the output of the gas turbine and the fuel supplied to the combustor. According to this aspect, the first minimum value can be set with simple measurement and in a short time.

[0058] (5) The valve control device 144 (control device) according to the fifth aspect is the valve control device 144 in (1) to (4), and the first minimum value is set based on the load corresponding to the minimum combustion temperature at which the flame can be maintained by the fuel injection by the premixed pilot nozzle. According to this aspect, the stability of the operation using the premixed pilot nozzle can be improved. Also, low NOx can be achieved.

Explanation of Reference Numerals

[0059] 1... Pilot combustion burner 3... Compressed air 4... Fuel 6... Main combustion burner 7… Main combustion nozzle 10… Premixed pilot nozzle 11… Diffusion pilot nozzle 112… Gas turbine 122… Combustor 124… Turbine 142… Fuel control valve 144… Valve control device 150… GVCSO calculation unit 154… MINCSO calculation unit 156… Selection unit 202, 203… Functions

Claims

1. A compressor, a combustor to which compressed air output from the compressor and fuel from a fuel flow path are supplied, a turbine rotated by combustion gas generated in the combustor, a control device for controlling a gas turbine comprising: controlling the gas turbine so that, during a load operation of the gas turbine, the flow rate of the fuel does not fall below a predetermined first minimum value that is greater than the full speed no load condition. The control device.

2. The combustor includes a premixed pilot nozzle and a diffusion pilot nozzle capable of independently controlling the injection amount of the fuel, changing the usage states of the premixed pilot nozzle and the diffusion pilot nozzle based on a predetermined value of the fuel flow rate that is greater than the first minimum value. The control device according to claim 1.

3. When the load of the gas turbine is cut off, setting a second minimum value smaller than the full speed no load condition for the fuel flow rate, and controlling the gas turbine so that the flow rate of the fuel does not fall below the second minimum value. The control device according to claim 2.

4. The first minimum value is calculated from the relationship between the intake temperature of the compressor and the output of the gas turbine, and the relationship between the output of the gas turbine and the fuel supplied to the combustor. The control device according to claim 2 or 3.

5. The first minimum value is set based on a load corresponding to the lowest combustion temperature at which a flame can be maintained by fuel injection from the premixed pilot nozzle. The control device according to claim 4.

6. A compressor, a combustor to which compressed air output from the compressor and fuel from a fuel flow path are supplied, a turbine rotated by combustion gas generated in the combustor, a control device for controlling the flow rate of the fuel, a gas turbine comprising: the control device controls the gas turbine so that, during a load operation of the gas turbine, the flow rate of the fuel does not fall below a predetermined first minimum value that is greater than the full speed no load condition. The gas turbine.

7. A compressor, a combustor to which compressed air output from the compressor and fuel from a fuel flow path are supplied, a turbine rotated by combustion gas generated in the combustor, a control method for controlling a gas turbine comprising: controlling the gas turbine so that, during a load operation of the gas turbine, the flow rate of the fuel does not fall below a predetermined first minimum value that is greater than the full speed no load condition. The control method.

Images