Intake air heating system, method for operating intake air heating system, and gas turbine system

Abstract

An intake air heating system configured to heat outside air flowing through an intake flow path communicating with a compressor of a gas turbine is provided with: a first heating unit including a return flow path for returning a portion of compressed air discharged from the compressor to the intake flow path; a second heating unit including a heater configured to heat the outside air using a heat source different from the compressed air; and a control device configured so as to control the second heating means such that the outside air is heated by the heater in a high load interval in which the gas turbine load is higher than the first predetermined load.

Description

Technical Field

[0001] The invention relates to an intake air heating system, an operation method of the intake air heating system and a gas turbine system.

[0002] This application claims priority based on Japanese Patent Application No. 2022-127617 filed with the Japan Patent Office on August 10, 2022, and the contents of which are incorporated herein by reference. Background Art

[0003] Conventionally, there is known an intake air heating system for heating external air supplied to a compressor of a gas turbine. For example, a heating unit of a gas turbine disclosed in Patent Document 1 is configured to heat external air using compressed air as a heat source. The heating unit includes a return line for returning a portion of the compressed air discharged from the compressor to the intake line. The compressed air flowing through the return line is mixed with external air flowing through the intake line, thereby heating the external air.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2000-097046 Summary of the invention

[0007] Technical issues to be solved by the invention

[0008] In the above-mentioned gas turbine, if the heating unit performs heating, the operating efficiency of the gas turbine may be reduced because part of the compressed air discharged from the compressor returns to the intake duct, and accordingly the flow rate of the combustion gas supplied to the turbine is reduced.

[0009] An object of the present invention is to provide an intake air heating system, an operating method of the intake air heating system, and a gas turbine system for improving the operating efficiency of a gas turbine.

[0010] Means for solving technical problems

[0011] An intake air heating system according to at least one embodiment of the present invention is configured to heat external air flowing through an intake air flow path communicating with a compressor of a gas turbine, and includes:

[0012] a first heating unit including a return flow path for returning a portion of the compressed air discharged from the compressor to the intake flow path;

[0013] a second heating unit including a heater configured to heat the outside air using a heat source different from the compressed air; and

[0014] The control device is configured to control the second heating means so that the outside air is heated by the heater in a high load section where the gas turbine load is higher than a first predetermined load.

[0015] Regarding an operating method of an intake air heating system according to at least one embodiment of the present invention, the intake air heating system is configured to heat external air flowing through an intake air flow path connected to a compressor of a gas turbine, wherein:

[0016] The intake air heating system comprises:

[0017] a first heating unit including a return flow path for returning a portion of the compressed air discharged from the compressor to the intake flow path; and

[0018] The second heating unit includes a heater configured to heat the outside air using a heat source different from the compressed air.

[0019] The operating method of the intake air heating system comprises:

[0020] The second heating means control step controls the second heating means so that the outside air is heated by the heater in a high load section where the gas turbine load is higher than a first predetermined load.

[0021] A gas turbine system according to at least one embodiment of the present invention includes:

[0022] the above-mentioned intake air heating system; and

[0023] The gas turbine.

[0024] Effects of the Invention

[0025] According to the present invention, it is possible to provide an intake air heating system for improving the operating efficiency of a gas turbine, an operating method of the intake air heating system, and a gas turbine system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of a gas turbine system according to an embodiment.

[0027] Figure 2 This is a schematic diagram showing a load range of a heating operation of the second heating unit according to one embodiment.

[0028] Figure 3 This is a schematic diagram showing a load range of a heating operation of a first heating unit according to an embodiment.

[0029] Figure 4 It is a schematic diagram which shows the 2nd heating means which concerns on one Embodiment.

[0030] Figure 5 This is a schematic diagram showing a heating ratio between the first heating unit and the second heating unit according to one embodiment.

[0031] Figure 6 It is a schematic diagram showing the details of a gas turbine according to one embodiment.

[0032] Figure 7 1 is a flowchart showing an operating method of an intake air heating system according to an embodiment. DETAILED DESCRIPTION

[0033] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described as embodiments or shown in the accompanying drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0034] For example, expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" indicating relative configuration or absolute configuration not only indicate such configuration in a strict sense, but also indicate a state of relative displacement at an angle or distance with a tolerance or a degree that the same function can be achieved.

[0035] For example, expressions such as “same”, “equal” and “homogeneous” indicating that things are in the same state not only indicate the same state in a strict sense, but also indicate a state with a tolerance or a difference in degree to which the same function can be obtained.

[0036] For example, expressions indicating shapes such as a quadrilateral or a cylinder not only indicate shapes such as a quadrilateral or a cylinder in a strict geometric sense, but also indicate shapes including concavo-convex portions or chamfered portions as long as the same effect can be obtained.

[0037] On the other hand, the expression “having”, “including” or “having” a constituent element is not an exclusive expression that excludes the existence of other constituent elements.

[0038] In addition, the same symbols are attached to the same structures, and the description thereof may be omitted.

[0039] <Overview of Gas Turbine System 1>

[0040] Figure 1Schematic diagram of a gas turbine system 1 according to an embodiment of the present invention. The gas turbine 3 constituting the gas turbine system 1 includes: a compressor 7; a burner 8 that generates a mixed fuel of compressed air generated by the compressor 7 and fuel; and a turbine 30 that is driven by the combustion gas discharged from the burner 8. The compressor 7 is configured to start rotating by the starter 4. As an example, the fuel supplied to the burner 8 is a gas fuel, but it may also be a liquid fuel. The turbine 30 of this example is configured to drive the generator 6 using the combustion gas discharged from the burner 8 as a power source. The exhaust gas discharged from the turbine 30 flows through the exhaust duct 39.

[0041] The compressor 7 is connected to the intake air path 9. The outside air flowing through the intake air path 9 is delivered to the compressor 7 to generate compressed air. The gas turbine system 1 of the present invention is provided with an intake air heating system 5 configured to heat the outside air flowing through the intake air path 9, and the intake air heating system 5 includes a first heating unit 10 and a second heating unit 20. The first heating unit 10 is configured to heat the outside air using the compressed air discharged from the compressor 7 as a heat source. More specifically, the first heating unit 10 includes a return flow path 15 for returning a part of the compressed air discharged from the compressor 7 to the intake air path 9. The outside air is heated by mixing the compressed air returned from the return flow path 15 to the intake air path 9 with the outside air.

[0042] The intake air flow path 9 illustrated in the figure includes a suction chamber 90 and an intake duct 95 communicating with the suction chamber 90 and the compressor 7, and the return flow path 15 communicates with a discharge pipe 99 accommodated in the suction chamber 90. The compressed air flowing from the return flow path 15 into the discharge pipe 99 is ejected into the suction chamber 90 from a nozzle provided on the discharge pipe 99. The discharge pipe 99 of this example is arranged between an intake filter 94 accommodated in the suction chamber 90 and an outlet 93 of the suction chamber 90.

[0043] The second heating unit 20 includes a heater 24 configured to heat the outside air using a heat source different from the compressor 7. The heat source of the heater 24 may be heat recovered from exhaust gas discharged from the turbine 30 (details will be described later) or heat obtained from a heating element that generates heat by supplying electricity. Figure 1 The heater 24 illustrated in FIG. 1 is accommodated in the suction chamber 90, and more specifically, is arranged between the intake filter 94 and the inlet 92 of the suction chamber 90. Alternatively, the heater 24 may be arranged between the intake filter 94 and the outlet 93.

[0044] The heating control of the second heating unit 20 is performed by the control device 80 which is a component of the intake air heating system 5. The control device 80 controls the second heating unit 20 in a high load range where the gas turbine load is higher than the first predetermined load so that the outside air is heated by the heater 24. The heating control of the second heating unit 20 by the control device 80 may be performed only in the high load range. Alternatively, the second heating unit 20 may also perform the heating operation in a range other than the high load range (refer to Figure 2 ).

[0045] Figure 2 1 is a schematic diagram showing a heating operation interval of the second heating unit 20 according to one embodiment. The horizontal axis of the graph represents the gas turbine load, and G1 corresponds to the first predetermined load ( Figure 3 , Figure 5 The first prescribed load is a load lower than the rated load of the gas turbine system 1, for example, any gas turbine load that is greater than 75% and less than 95% of the rated load. The amount of heat in the operating range of the second heating unit 20 shown in the diagram is not necessarily constant. For example, the amount of heat in the high load range may be feedback controlled based on the temperature of the exhaust gas discharged from the turbine 30, or the amount of heat in the high load range may be kept constant regardless of the temperature of the exhaust gas. In this example, the heating is controlled only when the gas turbine load exceeds a high prescribed load (given by Figure 3 In the case of a gas turbine load represented by G3 of FIG. 1 ), feedback control is performed, and in the case where the gas turbine load is below a high prescribed load, feedback control is not performed. In addition, the feedback control of the second heating unit 20 may be any of P control, PI control, or PID control, but PI control is adopted in this example. In addition, the operation of the gas turbine system 1 involved in one embodiment may always be partial load operation. At this time, the upper limit prescribed load (the gas turbine load represented by the symbol U) which is the maximum gas turbine load in the high load interval is lower than the rated load of the gas turbine system 1, so that operation in a load interval higher than the upper limit prescribed load is not performed. The upper limit prescribed load is, for example, any gas turbine load that is greater than 80% and less than 100% of the rated load. The upper limit prescribed load is a gas turbine load that is greater than the high prescribed load.

[0046] like Figure 2 As shown in the example, the second heating unit 20 performs heating operation not only in the high load section but also in the intermediate load section. The intermediate load section is a section where the gas turbine load is a gas turbine load that is higher than a second predetermined load lower than the first predetermined load and lower than the first predetermined load. G2 in the graph corresponds to the second predetermined load ( Figure 3 , Figure 5As an example, in the intermediate load range, feedback control based on the heating amount of the second heating unit 20 is not performed. As a more detailed example, in the intermediate load range, the opening of the second flow control valve 22 (described later) of the second heating unit 20 is maintained constant. In addition, the second specified load is an arbitrary gas turbine load that is greater than or equal to 30% and less than 60% of the rated load of the gas turbine system 1.

[0047] According to the above configuration, in the high load range, the outside air is heated by a heat source different from the compressed air. As a result, the flow rate of the compressed air flowing through the return flow path 15 as a heat source for heating the outside air can be reduced, so that the reduction in the flow rate of the combustion gas supplied to the turbine 30 can be suppressed in the high load range. Therefore, the intake air heating system 5 that improves the operating efficiency of the gas turbine 3 is realized.

[0048] <Details of the First Heating Unit 10>

[0049] Return to Figure 1 The first heating unit 10 further includes a first flow regulating valve 12 disposed in the return flow path 15. The heating operation of the first heating unit 10 is controlled by the control device 80. More specifically, the control device 80 sends a control signal to the first flow regulating valve 12 to control the flow rate of the compressed air flowing through the return flow path 15, thereby controlling the amount of heating of the external air by the first heating unit 10.

[0050] In one embodiment, in a low load interval where the gas turbine load is lower than a second specified load, a heating action based on the first heating unit 10 is performed. That is, in the low load interval, the control device 80 controls the first heating unit 10 so that the first flow control valve 12 opens the return flow path 15. In addition, the opening of the first flow control valve 12 does not necessarily mean that the first flow control valve 12 is fully open. If the opening degree of the first flow control valve 12 exceeds 0%, it can be understood that the first flow control valve 12 is opened (the same applies to the second flow control valve 22 described later). In addition, the heating control of the first heating unit 10 by the control device 80 can be performed only in the low load interval, and can also be performed in intervals other than the low load interval (refer to Figure 3 ).

[0051] Figure 3It is a schematic diagram chart showing the intervals of the heating action of the first heating unit 10 involved in one embodiment. The horizontal axis of the chart represents the gas turbine load. The heating amount of the working interval of the first heating unit 10 shown in the chart is not necessarily constant. For example, the heating amount in the low load interval can be feedback controlled according to the gas turbine load, or the heating amount in the low load interval can be kept constant regardless of the gas turbine load. In this example, the heating amount of the first heating unit 10 is feedback controlled in the low load interval. The feedback control of the first heating unit 10 can be any of P control, PI control or PID control, but PI control is used in this example.

[0052] like Figure 3 As shown in the example, the first heating unit 10 performs a heating action not only in a low load range but also in an intermediate load range. As a more detailed example, in the intermediate load range, feedback control of the heating amount of the second heating unit 20 is performed. In addition, specifically, in the intermediate load range, the opening of the first flow regulating valve 12 of the first heating unit 10 is feedback controlled according to the exhaust gas temperature. And, in the example of the figure, in the high load range, the heating action based on the second heating unit 20 is not performed. That is, in the high load range, the control device 80 controls the first heating unit 10 so that the first flow regulating valve 12 closes the return flow path 15.

[0053] According to the above structure, when the first flow control valve 12 is opened in the low load range, the compressed air discharged from the compressor 7 is extracted, and the compressed air extracted is used to heat the outside air. As a result, the flow rate of the compressed air flowing into the combustor 8 is reduced, and the flow rate of the combustion gas used to drive the turbine 30 is reduced. At this time, in order to maintain the output of the gas turbine system 1, the fuel supplied to the combustor 8 is increased. As a result, the combustion temperature in the combustor 8 is increased, so the amount of CO (carbon monoxide) generated can be suppressed. As a result, the generation of CO can be suppressed in the low load range, and the operating efficiency of the gas turbine 3 can be improved in the high load range. And, according to the above structure, in the high load range, the first flow control valve 12 closes the return flow path 15. As a result, in the high load range, the first heating unit 10 does not work, so the operating efficiency of the gas turbine 3 can be further improved.

[0054] <Details of the Second Heating Unit 20>

[0055] Figure 4 20 according to an embodiment of the present invention. The heat source of the second heating unit 20 illustrated in the figure is a turbine 30 (refer to Figure 1) is discharged from the waste heat recovery boiler 19. The heat source of the waste heat recovery boiler 19 is recovered by the waste heat recovery boiler 19, which is a component of the gas turbine system 1, and is used as a heat source for the second heating unit 20. The waste heat recovery boiler 19 is configured to generate a heating medium from the boiler feed water using the exhaust gas supplied from the exhaust pipe 39 as a heat source. The heating medium is hot water or steam (superheated steam). For example, high-temperature exhaust gas that has just flowed into the waste heat recovery boiler 19 heats the boiler feed water, thereby generating superheated steam. The superheated steam can be supplied to other equipment that constitutes the gas turbine system 1, such as a steam turbine. On the other hand, in the waste heat recovery boiler 19, hot water is generated by heating the boiler feed water with the low-temperature exhaust gas flowing near the outlet (the hot water can further flow in the waste heat recovery boiler 19 and become superheated steam through heat exchange with the high-temperature exhaust gas.).

[0056] The second heating unit 20 will be described below. The second heating unit 20 according to one embodiment includes: a heating medium flow path 29 for introducing the heating medium generated by the waste heat recovery boiler 19 into the suction chamber 90 of the intake air path 9; a second flow regulating valve 22 provided in the heating medium flow path 29; and a piping section 25, which is a heater 24 disposed in the intake air path 9. As described above, the second heating unit 20 is controlled by the control device 80. In this example, when the second flow regulating valve 22 is opened according to a control signal sent from the control device 80 to the second flow regulating valve 22, the heating medium is supplied from the waste heat recovery boiler 19 to the piping section 25 via the heating medium flow path 29. Furthermore, by controlling the opening of the second flow regulating valve 22, the flow rate of the heating medium flowing through the piping section 25 is controlled. Thus, the amount of heating of the outside air by the second heating unit 20 is controlled. Figure 2 For example, in the intermediate load range, as the gas turbine load increases, the opening of the second flow control valve 22 increases accordingly, and in the high load range, the opening of the second flow control valve 22 remains approximately constant. Figure 4 The heating medium flowing through the heating medium flow path 29 illustrated in FIG. 2 is hot water, and the hot water has a higher temperature than the boiler feed water before flowing into the waste heat recovery boiler 19 .

[0057] The control device 80 according to one embodiment controls the second heating unit 20 in the low load section so that the second flow regulating valve 22 closes the heating medium flow path 29. Therefore, in the low load section, the second heating unit 20 does not perform a heating operation on the outside air. According to the above structure, in the low load section, the second heating unit 20 does not heat the outside air, and accordingly, the flow rate of the compressed air flowing through the return flow path 15 can be increased. Therefore, in the low load section, the generation of CO can be further suppressed.

[0058] <Example of Heating Control of First Heating Unit 10 and Second Heating Unit 20>

[0059] Figure 5 This is a schematic diagram showing the heating ratio of the first heating unit 10 and the second heating unit 20 involved in one embodiment. The horizontal axis of the graph represents the gas turbine load, and the vertical axis represents the ratio of the heating amount of the first heating unit 10 and the second heating unit 20. For example, the first heating unit 10 is responsible for heating the outside air in the low load range, and the second heating unit 20 is responsible for heating the outside air in the high load range. In addition, Figure 5 The vertical axis of represents only the ratio of the heating amount of the first heating unit 10 and the heating amount of the second heating unit 20. Therefore, the heating amount of the outside air is not necessarily constant in the low load section, the medium load section, and the high load section.

[0060] exist Figure 5 In the intermediate load range illustrated in FIG. 1 , both the first heating unit 10 and the second heating unit 20 are responsible for heating. As a more specific example, the control device 80 controls the first heating unit 10 and the second heating unit 20 so that the first flow control valve 12 opens the return flow path 15 and the second flow control valve 22 opens the heating medium flow path 29. Figure 5 In the intermediate load section illustrated in FIG. 1 , as the gas turbine load increases, the heating ratio of the first heating unit 10 decreases, and the heating ratio of the second heating unit 20 increases. The reason for this is as follows.

[0061] In the feedback control of the first flow control valve 12 in the intermediate load range, the opening of the first flow control valve 12 is controlled based on, for example, the target value and the actual measured value of the exhaust gas temperature of the exhaust gas from the turbine 30. At this time, the amount of fuel supplied to the combustor 8 in order to increase the gas turbine load is relatively high, and as the gas turbine load increases, the exhaust temperature increases. As a result, feedback control is performed to reduce the opening of the first flow control valve 12, and the heating amount of the first heating unit 10 decreases. On the other hand, in the intermediate load range, control is performed so that as the gas turbine load increases, the heating amount of the second heating unit 20 increases. As a more specific example, as the gas turbine load increases, the opening of the second flow control valve 22 increases. Therefore, as the gas turbine load in the intermediate load range increases, the heating ratio of the first heating unit 10 decreases, and the heating ratio of the second heating unit 20 increases.

[0062] According to the above configuration, the first heating unit 10 and the second heating unit 20 are responsible for heating the outside air in the intermediate load range. This allows the gas turbine system 1 to operate in a balanced manner between suppressing CO generation and improving the operating efficiency of the gas turbine 3 .

[0063] <Details of Gas Turbine 3>

[0064] Figure 6: is a schematic diagram showing the details of the gas turbine 3 involved in one embodiment of the present invention. The gas turbine 3 in this figure is a dual-shaft gas turbine. In more detail, the gas turbine 3 includes: a compressor 7, a high-pressure turbine 33, having a first shaft 31 connected to the rotating shaft of the compressor 7; and a low-pressure turbine 34, having a second shaft 32 different from the first shaft 31. The high-pressure turbine 33 rotates integrally with the compressor 7. In addition, the low-pressure turbine 34 is configured to be supplied with exhaust gas from the high-pressure turbine 33, and is configured to rotate using the exhaust gas as a power source. The exhaust gas discharged from the low-pressure turbine 34 flows into the exhaust duct 39.

[0065] An inlet guide vane (IGV) is provided at the inlet of the compressor 7, and the intake amount of the compressor 7 is controlled by adjusting the opening of the inlet guide vane. In the twin-shaft gas turbine, the opening control of the inlet guide vane of the compressor 7 is performed to maintain the balance between the output of the high-pressure turbine 33 and the power of the compressor 7. Therefore, for example, when the turbine inlet temperature decreases due to a decrease in the amount of fuel supplied to the combustor 8 of the gas turbine 3, it is difficult to perform control to reduce the opening of the inlet guide vane to increase the turbine inlet temperature. In this regard, according to the above-mentioned structure, in the high load range, the second heating unit 20 heats the outside air using a heat source different from the compressed air, thereby increasing the turbine inlet temperature. Since the compressed air discharged from the compressor 7 is suppressed from being used as a heat source, the decrease in the flow rate of the combustion gas flowing into the turbine 30 can also be suppressed. As a result, the operating efficiency of the twin-shaft gas turbine can be improved.

[0066] <Operation Method of Intake Air Heating System 5>

[0067] Figure 7 : is a flowchart showing a method for operating the intake air heating system 5 involved in one embodiment of the present invention. As an example, the method is executed by the control device 80. For example, the control device 80 is composed of a computer, and has a processor, a memory and an external communication interface. The processor is a CPU, a GPU, an MPU, a DSP or a combination thereof. The processor involved in another embodiment can be implemented by an integrated circuit such as a PLD, an ASIC, an FPGA or an MCU. The memory is configured to store various data temporarily or non-temporarily, for example, by at least one of RAM, ROM or flash memory. According to the command of the program loaded into the memory, the processor of the control device 80 (hereinafter sometimes referred to as the "processor") performs control processing for operating the intake air heating system 5. During the execution of the control processing, the processor sends a control signal to the first flow control valve 12 and the second flow control valve 22. In the following description, the step is sometimes abbreviated as "S".

[0068] First, determine whether the gas turbine load is included in the low load interval (S11). For example, by obtaining an instruction from the processor indicating a specific gas turbine load, determine whether the gas turbine load is included in the low load interval. When it is determined that the gas turbine load is included in the low load interval (S11: Yes), the first heating unit control step (S13) of controlling the first heating unit 10 is executed. The control method of the first heating unit 10 in the low load interval is as described above, and the processor sends a prescribed control signal to the first flow control valve 12. And, at this time, the processor sends a control signal for causing the second flow control valve 22 to close the heating medium flow path 29. After executing S13, the operation method of the intake air heating system 5 ends.

[0069] When it is determined that the gas turbine load is not included in the low load interval (S11: No), it is determined whether the gas turbine load is included in the intermediate load interval (S15). The determination method of S15 is the same as the determination method of S11. When it is determined that the gas turbine load is included in the intermediate load interval (S15: Yes), a control step of controlling the first heating unit 10 and the second heating unit 20 is performed (S17). The control method of the first heating unit 10 and the second heating unit 20 in the intermediate load interval is as described above, and the processor sends a specified signal to the first flow control valve 12 and the second flow control valve 22, respectively. After executing S17, the operation method of the intake air heating system 5 ends.

[0070] When it is determined that the gas turbine load is not included in the intermediate load interval (S15: No), it is determined whether the gas turbine load is included in the high load interval (S19). The determination method of S19 is the same as the determination method of S11. When it is determined that the gas turbine load is included in the high load interval (S19: Yes), the second heating unit control step (S21) of controlling the second heating unit 20 is executed. The control method of the second heating unit 20 in the high load interval is as described above. And, at this time, the processor sends a control signal for causing the first flow control valve 12 to close the return flow path 15. After executing S21, the operating method of the intake air heating system 5 ends. In addition, when it is determined that the gas turbine load is not included in the high load interval (S19: No), the step returns to S11.

[0071] <Conclusion>

[0072] The contents described in some of the above-mentioned embodiments can be understood, for example, as follows.

[0073] 1) An intake air heating system 5 according to at least one embodiment of the present invention is configured to heat external air flowing through an intake air flow path 9 communicating with a compressor 7 of a gas turbine 3, and the intake air heating system 5 includes:

[0074] The first heating unit 10 includes a return flow path 15 for returning a part of the compressed air discharged from the compressor 7 to the intake flow path 9;

[0075] The second heating unit 20 includes a heater 24 configured to heat the outside air using a heat source different from the compressed air; and

[0076] The control device 80 is configured to control the second heating unit 20 so that the outside air is heated by the heater 24 in a high load range where the gas turbine load is higher than a first predetermined load.

[0077] According to the configuration of 1) above, in the high load range, the outside air is heated by a heat source different from the compressed air. As a result, the flow rate of the compressed air flowing through the return flow path 15, which is the heat source for heating the outside air, can be reduced, thereby suppressing the reduction in the flow rate of the combustion gas supplied to the turbine 30 in the high load range. Therefore, the intake air heating system 5 that improves the operating efficiency of the gas turbine 3 is realized.

[0078] 2) In some embodiments, according to the intake air heating system 5 described in 1) above, wherein:

[0079] The first heating unit 10 further includes a first flow control valve 12 disposed in the return flow path 15.

[0080] The control device 80 is configured to control the first heating unit 10 so that the first flow rate regulating valve 12 opens the return flow path 15 in a low load section where the gas turbine load is lower than a second predetermined load that is lower than the first predetermined load.

[0081] According to the structure of 2) above, when the first flow regulating valve 12 is opened in the low load range, the compressed air discharged from the compressor 7 is extracted, and the outside air is heated by the extracted compressed air. As a result, the flow rate of the compressed air flowing into the burner 8 is reduced, and the flow rate of the combustion gas driving the turbine 30 is reduced. At this time, in order to maintain the output of the gas turbine system 1, the fuel supplied to the burner 8 is increased. As a result, the combustion temperature in the burner 8 is increased, so the amount of CO (carbon monoxide) generated can be suppressed. As a result, the generation of CO can be suppressed in the low load range, and the operating efficiency of the gas turbine 3 can be improved in the high load range.

[0082] 3) In some embodiments, according to the intake air heating system 5 described in 2) above, wherein:

[0083] The control device 80 is configured to control the first heating unit 10 so that the first flow rate regulating valve 12 closes the return flow path 15 in the high load section.

[0084] According to the above-mentioned configuration 3), the first heating unit 10 does not operate in the high load section, so the operating efficiency of the gas turbine 3 can be further improved.

[0085] 4) In some embodiments, according to the intake air heating system 5 described in 3) above, wherein:

[0086] The second heating unit 20 includes:

[0087] a heating medium flow path 29 for introducing a heating medium generated by heating boiler feed water by the waste heat recovery boiler 19 supplied with exhaust gas from the gas turbine 3 into the intake flow path 9;

[0088] a second flow control valve 22 disposed in the heating medium flow path 29; and

[0089] The piping portion 25 is disposed in the intake air passage 9 and is configured to supply the heating medium from the heating medium passage 29 to the heater 24.

[0090] The control device 80 is configured to control the second heating unit 20 so that the second flow rate regulating valve 22 closes the heating medium flow path 29 in the low load section.

[0091] According to the configuration of 4), in the low load section, the second heating unit 20 does not heat the outside air, and accordingly, the flow rate of the compressed air flowing through the return flow path 15 can be increased. Therefore, in the low load section, the generation of CO can be further suppressed.

[0092] 5) In some embodiments, according to the intake air heating system 5 described in 4) above, wherein:

[0093] The control device 80 is configured to control the first heating unit 10 and the second heating unit 20 in an intermediate load range where the gas turbine load is above the second specified load and below the first specified load, so that the first flow regulating valve 12 opens the return flow path 15 and the second flow regulating valve 22 opens the heating medium flow path 29.

[0094] According to the configuration of 5), the first heating unit 10 and the second heating unit 20 are responsible for heating the outside air in the intermediate load range. This allows the gas turbine system 1 to operate in a balanced manner between suppressing CO generation and improving the operating efficiency of the gas turbine 3.

[0095] 6) Regarding the operating method of the intake air heating system 5 according to at least one embodiment of the present invention, the intake air heating system 5 is configured to heat the external air flowing through the intake air flow path 9 connected to the compressor 7 of the gas turbine 3, wherein:

[0096] The intake air heating system 5 comprises:

[0097] The first heating unit 10 includes a return flow path 15 for returning a part of the compressed air discharged from the compressor 7 to the intake flow path 9; and

[0098] The second heating unit 20 includes a heater 24 configured to heat the outside air using a heat source different from the compressed air.

[0099] The operating method of the intake air heating system 5 includes:

[0100] The second heating means control step ( S21 ) controls the second heating means 20 so that the outside air is heated by the heater 24 in a high load section where the gas turbine load is higher than a first predetermined load.

[0101] According to the configuration of 6), for the same reason as in 1), it is possible to realize an operating method of the intake air heating system 5 that improves the operating efficiency of the gas turbine 3.

[0102] 7) A gas turbine system 1 according to at least one embodiment of the present invention includes:

[0103] The intake air heating system 5 described in any one of 1) to 5) above; and

[0104] The gas turbine 3.

[0105] According to the configuration of 7), for the same reason as 1), it is possible to realize the gas turbine system 1 in which the operating efficiency of the gas turbine 3 is improved.

[0106] 8) In some embodiments, according to the gas turbine system 1 described in 7) above,

[0107] The gas turbine 3 is a dual-shaft gas turbine, and the gas turbine 3 comprises:

[0108] The compressor 7;

[0109] A high-pressure turbine 33 having a first shaft 31 connected to the rotating shaft of the compressor 7; and

[0110] The low-pressure turbine 34 includes a second shaft 32 that is different from the first shaft 31 , and is configured to be supplied with exhaust gas from the high-pressure turbine 33 .

[0111] In a twin-shaft gas turbine, the opening control of the inlet guide vane of the compressor 7 is performed to maintain the balance between the output of the high-pressure turbine 33 and the power of the compressor 7. Therefore, for example, when the turbine inlet temperature decreases due to a decrease in the amount of fuel supplied to the combustor 8 of the gas turbine 3, it is difficult to perform control to reduce the opening of the inlet guide vane to increase the turbine inlet temperature. In this regard, according to the structure of 8) above, the second heating unit 20 heats the outside air using a heat source different from the compressed air, thereby increasing the turbine inlet temperature. Since the compressed air discharged from the compressor 7 is suppressed from being used as a heat source, the reduction in the flow rate of the combustion gas flowing into the turbine 30 can also be suppressed. As a result, the operating efficiency of the twin-shaft gas turbine can be improved.

[0112] Explanation of symbols

[0113] 1-gas turbine system, 3-gas turbine, 5-intake air heating system, 7-compressor, 9-intake air flow path, 10-first heating unit, 12-first flow control valve, 15-return flow path, 19-waste heat recovery boiler, 20-second heating unit, 22-second flow control valve, 24-heater, 25-piping section, 29-heating medium flow path, 30-turbine, 31-first shaft, 32-second shaft, 33-high-pressure turbine, 34-low-pressure turbine, 80-control device.

Claims

1. An intake air heating system configured to heat external air flowing through an intake air flow path communicating with a compressor of a gas turbine, the intake air heating system comprising: a first heating unit including a return flow path for returning a portion of the compressed air discharged from the compressor to the intake flow path; a second heating unit including a heater configured to heat the outside air using a heat source different from the compressed air; and The control device is configured to control the second heating means so that the outside air is heated by the heater in a high load section where the gas turbine load is higher than a first predetermined load.

2. The intake air heating system according to claim 1, wherein: The first heating unit further includes a first flow rate regulating valve disposed in the return flow path. The control device is configured to control the first heating unit so that the first flow rate regulating valve opens the return flow path in a low load range where the gas turbine load is lower than a second predetermined load that is lower than the first predetermined load.

3. The intake air heating system according to claim 2, wherein: The control device is configured to control the first heating unit so that the first flow rate regulating valve closes the return flow path in the high load section.

4. The intake air heating system according to claim 2 or 3, wherein: The second heating unit comprises: a heating medium flow path for introducing a heating medium generated by heating boiler feed water by a waste heat recovery boiler supplied with exhaust gas from the gas turbine into the intake flow path; a second flow control valve disposed in the heating medium flow path; and a piping portion disposed in the intake air passage and configured to supply the heating medium from the heating medium passage to the heater, The control device is configured to control the second heating unit so that the second flow rate regulating valve closes the heating medium flow path in the low load section.

5. The intake air heating system according to claim 4, wherein: The control device is configured to control the first heating unit and the second heating unit in an intermediate load range where the gas turbine load is greater than the second specified load and less than the first specified load, so that the first flow control valve opens the return flow path and the second flow control valve opens the heating medium flow path.

6. A method for operating an intake air heating system, the intake air heating system being configured to heat external air flowing through an intake air flow path connected to a compressor of a gas turbine, wherein: The intake air heating system comprises: a first heating unit including a return flow path for returning a portion of the compressed air discharged from the compressor to the intake flow path; and The second heating unit includes a heater configured to heat the outside air using a heat source different from the compressed air. The operating method of the intake air heating system comprises: The second heating means control step controls the second heating means so that the outside air is heated by the heater in a high load section where the gas turbine load is higher than a first predetermined load.

7. A gas turbine system comprising: The intake air heating system according to any one of claims 1 to 3; and The gas turbine.

8. The gas turbine system according to claim 7, wherein: The gas turbine is a dual-shaft gas turbine, and the gas turbine comprises: the compressor; a high-pressure turbine having a first shaft connected to the rotating shaft of the compressor; and The low-pressure turbine has a second shaft different from the first shaft and is configured to be supplied with exhaust gas from the high-pressure turbine.

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