Simple cycle gas turbine plant and method of operating the same

Abstract

To provide a simple cycle gas turbine plant capable of suppressing damage inside a hub on the downstream side of a final stage moving blade of a turbine.SOLUTION: A simple cycle gas turbine plant including a gas turbine, an exhaust gas line through which exhaust gas of the gas turbine flows, and a denitration device, the denitration device including a denitration catalyst provided in the exhaust gas line, a blower fan for sending cooling air, and a cooling air line configured to supply the cooling air from the blower fan to a position on an upstream side of the denitration catalyst in the exhaust gas line, the simple cycle gas turbine plant further including a control device configured to control the blower fan on the basis of a parameter related to an exhaust gas flow rate of the gas turbine, the control device is configured to execute a small air volume operation mode in which the blower fan is operated at an air volume smaller than a rated air volume during at least a part of a start-up period of the gas turbine.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a simple cycle gas turbine plant and a method of operating the same. [Background technology]

[0002] Patent Document 1 discloses a combined cycle power plant configured to combine exhaust gas from a gas turbine with combustion air supplied to a heat recovery boiler. In this plant, to prevent combustion gas from flowing back from a forced draft fan that compresses the combustion air to the outlet side of the gas turbine, the outlet pressure of the gas turbine is measured with a pressure gauge, and a turbine outlet damper is closed when the outlet pressure of the turbine falls below a predetermined pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-082305 Summary of the Invention [Problem to be solved by the invention]

[0004] In simple-cycle gas turbine plants, which do not use a steam turbine to generate power, the exhaust gas temperature at the inlet of the NOx removal device is likely to be high compared to combined-cycle power plants because they do not have a steam turbine or other device for recovering exhaust gas energy. Therefore, one possible method for lowering the inlet temperature of the NOx removal device is to install a blower fan at the turbine outlet of the gas turbine to cool the turbine's exhaust gas. However, during startup of a gas turbine, the flow rate of the gas turbine's exhaust gas is lower than during rated operation. Therefore, using the blower fan would result in a large volume of cooling air flowing from the blower fan toward the turbine's exhaust gas outlet, increasing the pressure loss of the exhaust gas. As a result, the pressure near the outer peripheral surface of the hub downstream of the turbine's final-stage rotor blades would increase, causing the turbine exhaust gas to flow into the hub through grooves in the outer peripheral surface of the hub. This could potentially heat and damage the interior of the hub (e.g., vapor piping supplying lubricating oil to bearings, instruments measuring shaft vibration, etc.). Because the plant described in Patent Document 1 is a combined-cycle power plant, Patent Document 1 does not disclose any knowledge for solving this problem in simple-cycle gas turbine plants.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide a simple cycle gas turbine plant and an operating method thereof that can suppress damage to the inside of a hub downstream of a turbine's last stage rotor blades. [Means for solving the problem]

[0006] In order to achieve the above object, a simple cycle gas turbine plant according to at least one embodiment of the present disclosure comprises: A simple cycle gas turbine plant including a gas turbine, an exhaust gas line through which exhaust gas from the gas turbine flows, and a denitration device, The denitration device is a denitration catalyst provided in the exhaust gas line; a blower fan for supplying cooling air; a cooling air line configured to supply the cooling air from the blower fan to a position in the exhaust gas line upstream of the denitration catalyst; Including, the simple cycle gas turbine plant further comprises a control device configured to control the blower fan based on a parameter related to an exhaust gas flow rate of the gas turbine; The control device is configured to execute a small air volume operation mode in which the blower fan is operated at an air volume smaller than a rated air volume during at least a part of a period during startup of the gas turbine. [Effects of the Invention]

[0007] According to at least one embodiment of the present disclosure, a simple cycle gas turbine plant and an operating method thereof are provided that can suppress damage to the inside of a hub downstream of a rotor blade in a final stage of a turbine. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of a simple cycle gas turbine plant 2 according to an embodiment. [Figure 2] 2 is a schematic cross-sectional view showing an example of a part of a cross section of a turbine 24 along the axial direction. [Figure 3] FIG. 2 is a block diagram showing an example of the hardware configuration of a control device 90. [Figure 4] 4 is a diagram showing an example of a control flow of the control device 90 when the gas turbine 4 is started up. FIG. [Figure 5] This figure shows an example of time series changes during startup of the gas turbine 4, in terms of the rotation speed N of the gas turbine 4, the blade path temperature BPT, which is the temperature of the combustion gas at the position of the final stage rotor blade 38, and the pressure Ph at position A1 (position near the gap 49) near the diffuser inner wall 45 at the diffuser inlet 44A. [Figure 6] 4 is a schematic cross-sectional view showing another example of a portion of a cross section of the turbine 24 along the axial direction. FIG. [Figure 7]10 is a diagram showing another example of the control flow of the control device 90 when the gas turbine 4 is started up. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0010] FIG. 1 is a diagram showing a schematic configuration of a simple cycle gas turbine plant 2 (hereinafter simply referred to as "gas turbine plant 2") according to one embodiment.

[0011] As shown in FIG. 1, the gas turbine plant 2 includes a gas turbine 4, a generator 6, an exhaust gas line 8, a denitration device 10, a chimney 12, a tachometer 14, a blower fan 32, a cooling air line 34, and a control device 90.

[0012] The gas turbine 4 includes a compressor 20 that compresses air, a combustor 22 that burns fuel using the compressed air generated by the compressor 20, and a turbine 24 that is driven by the combustion gas generated by the combustor 22, and the compressor 20 and the turbine 24 are connected via a rotating shaft 25. A start-up motor 5 for starting the gas turbine 4 is connected to the gas turbine 4, and when the gas turbine 4 is started up, a rotor 9 of the gas turbine 4 starts to rotate by the start-up motor 5. The tachometer 14 is configured to measure the rotation speed of the gas turbine 4. In this specification, the start-up of the gas turbine 4 refers to the period from when the rotor 9 of the gas turbine 4 starts to rotate to when the rotation speed of the rotor 9 (i.e., the rotation speed of the gas turbine 4) reaches the rated rotation speed.

[0013] The generator 6 is connected to the turbine 24, and is configured to generate electricity by driving the turbine 24 with combustion gas generated in the combustor 22.

[0014] The exhaust gas line 8 extends from an exhaust gas outlet in the turbine 24 to the chimney 12 , and the exhaust gas from the gas turbine 4 (exhaust gas from the turbine 24 ) flows through the exhaust gas line 8 and is discharged from the chimney 12 .

[0015] The denitration device 10 is configured to remove NOx in the exhaust gas of the gas turbine 4 by the SCR method (selective catalytic reduction method). The denitration device 10 uses a denitration catalyst (not shown) provided in the exhaust gas line 8 to reduce nitrogen oxides (NOx) in the exhaust gas of the gas turbine 4 using ammonia (NH3) or urea (CO(NH2)2) as a reducing agent, and decomposes the NOx into nitrogen (N2) and water vapor (HO).

[0016] The blower fan 32 is configured to take in outside air and send out cooling air. One end of a cooling air line 34 is connected to the blower fan 32, and the other end of the cooling air line 34 is connected to a position upstream of the denitration device 10 in the exhaust gas line 8. The cooling air line 34 is configured to supply the cooling air from the blower fan 32 to a position upstream of the denitration device 10 in the exhaust gas line 8.

[0017] The control device 90 is configured to control the operation of the blower fan 32. The control device 90 is configured to be able to execute a rated operation mode in which the blower fan 32 is operated at the rated airflow rate of the blower fan 32, and a small airflow rate operation mode in which the blower fan 32 is operated at an airflow rate that is lower than the rated airflow rate of the blower fan 32. In the small airflow rate operation mode, the control device 90 may operate the blower fan 32 at an airflow rate that is, for example, 10% to 50% of the rated airflow rate. Details of the control by the control device 90 will be described later.

[0018] FIG. 2 is a schematic cross-sectional view showing a part of the turbine 24 in the axial direction. As shown in FIG. 2 , the turbine 24 includes an exhaust casing 40 through which combustion gas flows after passing through the final-stage rotor blades 38 of the turbine 24. The exhaust casing 40 is located downstream of the final-stage rotor blades 38 in the flow direction of the combustion gas. In the following description, unless otherwise specified, "axial direction" refers to the axial direction of the turbine 24, "radial direction" refers to the radial direction of the turbine 24, and "circumferential direction" refers to the circumferential direction of the turbine 24 unless otherwise specified. The final-stage rotor blade 38 is the rotor blade located furthest downstream in the axial direction among the rotor blades included in the turbine 24. The final-stage rotor blade 38 includes an airfoil portion 38a and a plate-shaped platform portion 38b connected to the inner end of the airfoil portion 38a in the radial direction.

[0019] 2, the exhaust casing 40 includes a cylindrical casing wall 41 extending axially, a bearing housing 42 arranged radially inside the casing wall 41, a plurality of struts 50 extending substantially radially around the central axis CA of the turbine 24 to connect the casing wall 41 and the bearing housing 42, and a plurality of strut covers 51 covering the outer surfaces of the plurality of struts 50. The bearing housing 42 supports and houses a bearing 47 that rotatably supports the rotating shaft 25 of the turbine 24, and is supported by the casing wall 41 via the plurality of struts 50.

[0020] The exhaust casing 40 further includes a cylindrical diffuser outer peripheral wall 43 disposed radially inside the casing wall 41, a cylindrical diffuser inner peripheral wall 45 disposed radially inside the diffuser outer peripheral wall 43 and forming a diffuser flow path 44 between the diffuser outer peripheral wall 43 and the diffuser outer peripheral wall 43, and a partition wall 46 provided between the diffuser inner peripheral wall 45 and the bearing housing 42. The diffuser outer peripheral wall 43, the diffuser inner peripheral wall 45, and the partition wall 46 each extend along the axial direction of the turbine 24. A strut cover 51 connects the diffuser outer peripheral wall 43 and the diffuser inner peripheral wall 45. The platform portion 38b of the last stage rotor blade 38 and the diffuser inner peripheral wall 45 form a hub 53.

[0021] The diffuser passage 44 receives the combustion gas that has passed through the final stage rotor blades 38 of the turbine 24, and is formed in an annular shape with a cross-sectional area that gradually increases downstream. The flow of the combustion gas sent to the diffuser passage 44 is decelerated, and the kinetic energy of the combustion gas is converted into pressure (static pressure recovery).

[0022] 2, an intake port 412 is formed in the cabin wall 41 to take in cooling air from the outside. The intake port 412 penetrates the cabin wall 41 radially from the inside to the outside. The diffuser outer peripheral wall 43 is provided radially inwardly and spaced apart from the cabin wall 41, and a first cooling passage 481 is formed between the diffuser outer peripheral wall 43 and the cabin wall 41. The strut cover 51 is provided with its inner surface spaced apart from the outer surface of the strut 50, and a second cooling passage 482 is formed between the strut cover 51 and the strut 50. The diffuser inner peripheral wall 45 is provided radially outwardly and spaced apart from the partition wall 46, and a third cooling passage 483 is formed between the diffuser inner peripheral wall 45 and the partition wall 46.

[0023] First cooling passage 481 communicates with inlet 412 and is configured to allow the cooling air introduced from inlet 412 to circulate therethrough. Second cooling passage 482 communicates with first cooling passage 481 and is configured to allow the cooling air to circulate therethrough. Third cooling passage 483 communicates with second cooling passage 482 and is configured to allow the cooling air to circulate therethrough.

[0024] The cooling air introduced into the exhaust casing 40 from the intake port 412 flows through the first cooling passage 481, the second cooling passage 482 and the third cooling passage 483 in this order, cooling the parts facing these cooling passages 481, 482, 483 (e.g., the diffuser outer wall 43, the diffuser inner wall 45, the strut 50 and the strut cover 51, etc.) and the inside of the hub 53 (e.g., the vapor pipe (not shown) that supplies lubricating oil to the bearing 47 and the sensor (not shown) that measures the axial vibration of the rotating shaft 25, etc.), thereby preventing these parts from becoming too hot.

[0025] A gap 49 (hub groove) is formed between the platform portion 38b of the final stage rotor blade 38 on the outer peripheral surface 54 of the hub 53 and the diffuser inner peripheral wall 45, and the gap 49 connects a diffuser inlet 44A, which is the upstream end of the diffuser flow path 44, with the third cooling passage 483. When the gas turbine 4 is in operation, the pressure of the combustion gas at the diffuser inlet 44A is normally negative compared to the outside air around the turbine 24, so that the pressure difference between the outside air around the turbine 24 and the negative pressure causes the outside air to be introduced from the intake 412 as the above-mentioned cooling air, and after passing through the cooling passages 481, 482, and 483, is discharged from the gap 49 into the diffuser flow path 44 (see arrows a1 to a3).

[0026] Here, under low flow rate conditions of the turbine 24 when the gas turbine 4 is started up, the turbine flow rate is smaller than that during rated operation of the gas turbine 4. Therefore, if the blower fan 32 (see FIG. 1) is operated at the rated air flow rate, a large amount of cooling air flows from the blower fan 32 toward the exhaust gas outlet of the turbine 24, increasing the pressure loss of the exhaust gas. As a result, the pressure in the diffuser flow passage 44 downstream of the last-stage rotor blade 38 of the turbine 24 increases, and the exhaust gas from the turbine 24 flows into the inside of the hub 53 (the third cooling passage 483, etc.) through the gap 49 between the platform portion 38b of the last-stage rotor blade 38 and the diffuser inner circumferential wall 45, which may heat and damage internal structures of the hub 53 (for example, a vapor pipe (not shown) that supplies lubricating oil to the bearings 47, an instrument (not shown) that measures shaft vibration, etc.).

[0027] Therefore, the control device 90 performs the following control to suppress damage to the inside of the hub 53 downstream of the last stage rotor blades 38 of the turbine 24.

[0028] FIG. 3 is a block diagram showing an example of the hardware configuration of the control device 90. As shown in FIG. 3, the control device 90 is configured using a computer including, for example, a processor 91, a RAM (Random Access Memory) 92, a ROM (Read Only Memory) 93, an HDD (Hard Disk Drive) 94, an input I / F 96, and an output I / F 98, all of which are connected to one another via a bus 95. The control device 90 is also configured by the computer executing a program that realizes each function of the control device 90. The functions of each part of the control device 90 described below are realized, for example, by loading a program stored in ROM 93 into RAM 92 and executing it with the processor 91, as well as by reading and writing data from and to the RAM 92 and ROM 93. The hardware that makes up the control device 90 may be concentrated in one location or may be distributed across multiple locations.

[0029] 4 is a diagram showing an example of a control flow of the control device 90 at the start-up of the gas turbine 4. Each control shown in FIG.

[0030] As shown in FIG. 4 , in S11, the control device 90 starts the rotation of the rotor 9 of the gas turbine 4 by the startup motor 5, thereby increasing the rotation speed of the gas turbine 4. In S12, the control device 90 determines whether the rotation speed N of the gas turbine 4 measured by the revolution counter 14 has exceeded a first threshold value N1. If it is determined in S12 that the rotation speed N of the gas turbine 4 has exceeded the first threshold value N1, the control device 90 starts the blower fan 32 and operates the blower fan 32 in the small air volume mode operation mode in S13. If it is determined in S12 that the rotation speed N of the gas turbine 4 has not exceeded the first threshold value N1, the process returns to S11 and continues to increase the rotation speed N of the gas turbine 4 by the startup motor 5. Here, the first threshold value N1 is a rotation speed smaller than the rotation speed Ni of the gas turbine 4 corresponding to the timing of ignition of the combustor 22 (hereinafter referred to as the "ignition rotation speed Ni"). For example, the first threshold value N1 may be set to a value smaller than the rated rotation speed N of the gas turbine 4. rated The rotation speed may be 10% or more and 20% or less of the above.

[0031] In S14, the control device 90 increases the rotation speed N of the gas turbine 4 using the startup motor 5 until it reaches the ignition rotation speed Ni, and ignites the combustor 22 at the timing when the rotation speed N of the gas turbine 4 stabilizes at the ignition rotation speed Ni.

[0032] In S15, the control device 90 controls the amount of fuel input to the combustor 22 to further increase the rotation speed N of the gas turbine 4.

[0033] In S16, the control device 90 determines whether the rotation speed N of the gas turbine 4 has exceeded the second threshold value N2. If it is determined in S16 that the rotation speed N of the gas turbine 4 has exceeded the second threshold value N2, then in S17 the control device 90 switches the operation mode of the blower fan 32 from the small air volume operation mode to the rated operation mode. If it is determined in S16 that the rotation speed N of the gas turbine 4 has not exceeded the second threshold value N2, then the process returns to S15 and the control device 90 continues to increase the rotation speed N of the gas turbine 4. In S18, the control device 90 increases the amount of fuel input to the combustor 22 to increase the rotation speed N of the gas turbine 4 to the rated rotation speed N of the gas turbine 4. rated The second threshold value N2 is a rotational speed that is greater than the ignition rotational speed Ni, for example, the rated rotational speed N rated The rotation speed may be 20% or more and 40% or less of the above.

[0034] FIG. 5 shows an example of time-series changes in the rotation speed N of the gas turbine 4, the blade path temperature BPT, which is the temperature of the combustion gas at the position of the final stage rotor blade 38 in the turbine 24, and the pressure Ph at a position A1 (near the gap 49) near the hub 53 at the diffuser inlet 44A, during a partial period of startup of the gas turbine 4. In the graph of pressure Ph in FIG. 5, the pressure Ph when the blower fan 32 is stopped is indicated by a dashed-dotted line, the pressure Ph when the blower fan 32 is operating in the small airflow operation mode is indicated by a solid line, and the pressure Ph when the blower fan 32 is operating in the rated operation mode is indicated by a dashed-two-dot line. Here, the pressure Ph is a gauge pressure when atmospheric pressure is set to 0. In the example shown in FIG. 5, the small airflow operation mode is a mode in which the blower fan 32 is operated at a constant airflow rate of 1 / 6 of the rated airflow rate.

[0035] Furthermore, in the example shown in Figure 5, the rotor 9 of the gas turbine 4 starts rotating at time t0, but for the sake of convenience of explanation, only data for a partial period during the startup of the gas turbine 4 is displayed for the pressure Ph, blade path temperature BPT, and gas turbine rotation speed N.

[0036] When the gas turbine 4 is started up and the blower fan 32 is operated in the rated operation mode, a large volume of cooling air flows from the blower fan 32 toward the exhaust gas outlet of the turbine 24, increasing the pressure loss of the exhaust gas. As a result, as shown by the dashed double-dashed line in the upper graph of Figure 5, a period (a period up to time t3) occurs during which the pressure Ph becomes positive, and the exhaust gas from the turbine 24 flows into the inside of the hub 53 through the gap 49, which may heat and damage internal structures of the hub 53 (for example, a vapor pipe that supplies lubricating oil to the bearings, an instrument that measures shaft vibration, etc.).

[0037] Furthermore, when the gas turbine 4 is started up, if the blower fan 32 is operated in the small air volume operation mode, as shown by the solid line in the upper graph of Figure 5, the pressure Ph becomes a positive pressure in the period up to time t1 (the period up to when the rotation speed N of the gas turbine 4 reaches the first threshold value N1).

[0038] Therefore, as described above, when starting up the gas turbine 4, the control device 90 starts up the blower fan 32 and initiates the small air volume operation mode at timing t1 that is after timing t0 when the rotor 9 of the gas turbine 4 starts to rotate and before timing t2 when ignition occurs in the combustor 22. For example, when starting up the gas turbine 4, the control device 90 maintains a state in which the operation of the blower fan 32 is stopped until the rotation speed N of the gas turbine 4 measured by the rotation speed meter 14 exceeds a first threshold value N1 that is smaller than the ignition rotation speed Ni, and when the rotation speed N of the gas turbine 4 measured by the rotation speed meter 14 exceeds the first threshold value N1, the control device 90 starts up the blower fan 32 and initiates the small air volume operation mode.

[0039] Furthermore, the control device 90 switches the operation mode of the blower fan 32 from the small air volume operation mode to the rated operation mode at timing t3, which is after timing t2 at which the combustor 22 is ignited and before timing at which the rotation speed of the gas turbine reaches the rated rotation speed. Specifically, the control device 90 switches the operation mode of the blower fan 32 from the small air volume operation mode to the rated operation mode when the rotation speed N of the gas turbine 4 measured by the rotation speed meter 14 exceeds a second threshold value N2 that is higher than the ignition rotation speed Ni.

[0040] Here, the effects achieved by the gas turbine plant 2 will be described. According to the gas turbine plant 2, by supplying cooling air from the blower fan 32 via the cooling air line 34 to a position in the exhaust gas line 8 upstream of the denitration device 10, the temperature of the exhaust gas flowing into the denitration device 10 can be lowered, thereby suppressing damage to the denitration device 10. Furthermore, by executing a small air volume operation mode in which the blower fan 32 is operated at an air volume lower than the rated air volume during at least a part of the startup period of the gas turbine 4, an increase in pressure loss of the exhaust gas on the outlet side of the turbine 24 in the gas turbine 4 can be suppressed compared to a case in which the blower fan 32 is operated at the rated air volume throughout the startup period of the gas turbine 4. As a result, a pressure increase in the diffuser passage 44 can be suppressed during at least a part of the startup period of the gas turbine 4, and therefore, gas that has passed through the final stage rotor blades 38 of the turbine 24 is prevented from flowing into the interior of the hub 53 via the grooves (the gaps 49) in the outer peripheral surface 54 of the hub 53, thereby reducing the risk of the interior of the hub 53 being heated and damaged.

[0041] Furthermore, when the gas turbine 4 is started, the pressure of the exhaust gas from the turbine 24 in the gas turbine 4 decreases as the rotation speed N of the gas turbine 4 increases. Therefore, if the blower fan 32 is started at timing t0 when the rotor 9 of the gas turbine 4 starts to rotate or at a timing earlier than timing t0, a period is likely to occur during which the pressure Ph near the outer peripheral surface 54 of the hub 53 downstream of the last stage rotor blades 38 of the turbine 24 becomes positive, and the combustion gas that has passed through the last stage rotor blades 38 of the turbine 24 is likely to flow into the inside of the hub 53 via the grooves in the outer peripheral surface 54 of the hub 53 (the above-mentioned gap 49). For this reason, by setting the timing t1 when the blower fan 32 is started and the small air volume operation mode is started after timing t0 when the rotor 9 of the gas turbine 4 starts to rotate, as described above, a period during which the pressure Ph becomes positive is unlikely to occur, and it is possible to prevent the combustion gas that has passed through the last stage rotor blades 38 of the turbine 24 from flowing into the inside of the hub 53 via the grooves in the outer peripheral surface 54 of the hub 53 (the above-mentioned gap 49). This reduces the risk of the inside of the hub 53 being heated and damaged.

[0042] Furthermore, if the timing t1 at which the blower fan 32 is started and the small air volume operation mode is initiated is set later than the timing t2 at which the combustor 22 is ignited, there is a possibility that a period will occur during which the high-temperature exhaust gas from the gas turbine 4 flows into the denitration device 10 without being cooled by the blower fan 32, which is likely to cause damage to the denitration device 10. Therefore, by setting the timing t1 at which the blower fan 32 is started and the small air volume operation mode to be earlier than the timing t2 at which the combustor 22 is ignited, as described above, it is possible to prevent the high-temperature exhaust gas from the gas turbine 4 from flowing into the denitration device 10 without being cooled by the blower fan 32, and to suppress damage to the denitration device 10.

[0043] In some embodiments, the control device 90 may control the blower fan 32 based on the outlet pressure of the gas turbine 4. In this case, for example, as shown in FIG. 6, a pressure gauge 55 (see FIG. 6) may be provided that measures the pressure Ph in the diffuser passage 44 as the outlet pressure of the gas turbine 4, and the control device 90 may control the blower fan 32 based on the pressure Ph measured by the pressure gauge 55, as illustrated in FIG. 7.

[0044] 7 is a diagram showing another example of the control flow of the control device 90 at the start-up of the gas turbine 4. The respective controls shown in FIG.

[0045] As shown in FIG. 7 , in S21, the control device 90 starts rotation of the rotor 9 of the gas turbine 4 by the startup motor 5, thereby increasing the rotation speed of the gas turbine 4. In S22, the control device 90 determines whether the pressure Ph measured by the pressure gauge 55 has fallen below a first threshold value Ph1. If it is determined in S22 that the pressure Ph has fallen below the first threshold value Ph1, the control device 90 starts the blower fan 32 and operates the blower fan 32 in the small air volume operation mode in S23. If it is determined in S22 that the pressure Ph is not below the first threshold value Ph1, the process returns to S21 and continues to increase the rotation speed N of the gas turbine 4 by the startup motor 5. Here, the first threshold value Ph1 may be a pressure at which the pressure Ph does not become higher than atmospheric pressure even when the blower fan 32 is operated in the small air volume operation mode.

[0046] In S24, the control device 90 increases the rotation speed N of the gas turbine 4 using the startup motor 5 until it reaches the ignition rotation speed Ni, and ignites the combustor 22 at the timing when the rotation speed N of the gas turbine 4 stabilizes at the ignition rotation speed Ni.

[0047] In S25, the control device 90 controls the amount of fuel input to the combustor 22 to further increase the rotation speed N of the gas turbine 4.

[0048] In S26, the control device 90 determines whether the pressure Ph measured by the pressure gauge 55 has fallen below the second threshold value Ph2. If it is determined in S26 that the pressure Ph has fallen below the second threshold value N2, then in S27 the control device 90 switches the operation mode of the blower fan 32 from the small air volume operation mode to the rated operation mode. If it is determined in S26 that the pressure Ph has not fallen below the second threshold value Ph2, then the process returns to S25 and the rotation speed N of the gas turbine continues to increase. In S28, the control device 90 increases the amount of fuel input to the combustor 22 to raise the rotation speed N of the gas turbine 4 to the rated rotation speed N of the gas turbine 4. ratedto complete the start-up of the gas turbine 4. The second threshold value Ph2 is a pressure lower than the first threshold value Ph1, and may be a pressure that prevents the pressure Ph from becoming higher than atmospheric pressure even when the blower fan 32 is operated in the rated operation mode.

[0049] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0050] 4 and the like, the blower fan 32 is started and the small air volume operation mode is initiated at timing t1 after the rotor 9 of the gas turbine 4 starts to rotate, but the blower fan 32 may be started and the small air volume operation mode may be initiated simultaneously with the start of rotation of the rotor 9 or before the start of rotation of the rotor 9. However, from the viewpoint of making it less likely that a period will occur in which the pressure Ph near the outer circumferential surface 54 of the hub 53 downstream of the last stage rotor blades 38 of the turbine 24 becomes a positive pressure, it is preferable that the blower fan 32 be started and the small air volume operation mode be initiated after the rotor 9 starts to rotate.

[0051] 4 and the like, the blower fan 32 is started and the small air volume operation mode is initiated at timing t1, which is before timing t2 of ignition in the combustor 22. However, the timing of starting the blower fan 32 and starting the small air volume operation mode may be after timing t2 of ignition in the combustor 22. Even in this case, by operating the blower fan 32 in the small air volume operation mode for at least a part of the startup period of the gas turbine 4, it is possible to suppress an increase in the pressure Ph compared to, for example, a case in which the blower fan 32 is operated in the rated operation mode for the entire startup period of the gas turbine 4. This prevents the combustion gas that has passed through the final stage rotor blades 38 of the turbine 24 from flowing into the interior of the hub 53 via the grooves (gaps 49) in the outer peripheral surface 54 of the hub 53, thereby reducing the risk of the interior of the hub 53 being heated and damaged.

[0052] Furthermore, in the above-described embodiment, the rotation speed N and the pressure Ph are given as examples of parameters related to the flow rate of the exhaust gas of the gas turbine 4, but the parameters related to the flow rate of the exhaust gas of the gas turbine 4 may be parameters other than the rotation speed N and the pressure Ph.

[0053] The contents described in each of the above embodiments can be understood, for example, as follows.

[0054] [1] A simple cycle gas turbine plant according to at least one embodiment of the present disclosure (e.g., the above-described simple cycle gas turbine plant 2) includes: a gas turbine (e.g., gas turbine 4 described above); an exhaust gas line (for example, the above-mentioned exhaust gas line 8) through which exhaust gas from the gas turbine flows; a denitration device (for example, the above-mentioned denitration device 10) provided in the exhaust gas line; a blower fan (for example, the above-mentioned blower fan 32) for blowing cooling air; a cooling air line (for example, the above-mentioned cooling air line 34) configured to supply the cooling air from the blower fan to a position in the exhaust gas line upstream of the denitration device; a control device (for example, the above-mentioned control device 90) configured to control the blower fan based on a parameter related to the exhaust gas flow rate of the gas turbine (for example, the above-mentioned rotation speed N or pressure Ph); Equipped with The control device is configured to execute a small air volume operation mode in which the blower fan is operated at an air volume smaller than a rated air volume during at least a part of a period during startup of the gas turbine.

[0055] According to the simple cycle gas turbine plant described in [1] above, by supplying cooling air from the blower fan via a cooling air line to a position in the exhaust gas line upstream of the denitration device, the temperature of the exhaust gas flowing into the denitration device can be lowered, thereby suppressing damage to the denitration device. Furthermore, by operating the blower fan at a lower airflow rate than the rated airflow rate during at least a portion of the startup period of the gas turbine, an increase in exhaust gas pressure loss at the turbine outlet side of the gas turbine can be suppressed compared to when the blower fan is always operated at the rated airflow rate during startup. This suppresses a pressure increase downstream of the turbine's last-stage rotor blades during at least a portion of the startup period of the gas turbine. This prevents gas that has passed through the last-stage rotor blades from flowing into the hub via the grooves on the surface of the hub, thereby reducing the risk of the inside of the hub being heated and damaged.

[0056] [2] In some embodiments, in the simple cycle gas turbine plant described in [1] above, The control device is configured to start the blower fan and initiate the small air volume operation mode after the rotor of the gas turbine (e.g., the rotor 9 described above) starts to rotate and before the combustor of the gas turbine is ignited.

[0057] During startup of a gas turbine, the turbine exhaust pressure decreases as the gas turbine rotation speed increases. Therefore, if the blower fan is started at or before the start of rotation of the gas turbine rotor, a period in which the pressure near the outer circumferential surface of the hub downstream of the turbine's last-stage rotor blades becomes positive is likely to occur, and gas that has passed through the turbine's last-stage rotor blades is likely to flow into the inside of the hub via the grooves in the outer circumferential surface of the hub. Therefore, by starting the blower fan and entering the small air volume operation mode after the start of rotation of the gas turbine rotor as described in [2] above, a period in which the pressure near the outer circumferential surface of the hub downstream of the turbine's last-stage rotor blades becomes positive is unlikely to occur, and gas that has passed through the turbine's last-stage rotor blades is prevented from flowing into the inside of the hub via the grooves in the outer circumferential surface of the hub. This reduces the risk of the inside of the hub being heated and damaged.

[0058] Furthermore, if the timing for starting the blower fan and initiating the small air volume operation mode is set after the timing for igniting the combustor, there is a possibility that a period will occur during which the high-temperature exhaust gas from the gas turbine flows into the denitration device without being cooled by the blower fan, which is likely to cause damage to the denitration device. Therefore, by setting the timing for starting the blower fan and initiating the small air volume operation mode before ignition of the combustor as described in [2] above, it is possible to prevent the high-temperature exhaust gas from the gas turbine from flowing into the denitration device without being cooled by the blower fan, thereby suppressing damage to the denitration device.

[0059] [3] In some embodiments, in the simple cycle gas turbine plant described in [2] above, the parameter is the rotational speed of the gas turbine (for example, the rotational speed N mentioned above), The control device is configured to start the blower fan and initiate the small air volume operation mode when the rotation speed of the gas turbine exceeds a first threshold value (e.g., the above-mentioned first threshold value N1) that is smaller than the rotation speed corresponding to the ignition timing of the combustor (e.g., the above-mentioned ignition rotation speed Ni).

[0060] According to the simple cycle gas turbine plant described in [3] above, the rotation speed that is normally monitored in a typical gas turbine can be used as the parameter to obtain the effect described in [2] above.

[0061] [4] In some embodiments, in the simple cycle gas turbine plant according to either [2] or [3] above, the control device is configured to be able to execute a rated operation mode in which the blower fan is operated at a rated air volume; The control device is configured to switch from the small air volume operation mode to the rated operation mode after the rotor of the gas turbine starts to rotate and after ignition of a combustor of the gas turbine.

[0062] According to the simple cycle gas turbine plant described in [4] above, after the combustor is ignited, the high-temperature exhaust gas from the gas turbine is appropriately cooled by the blower fan, thereby suppressing damage to the denitration device.

[0063] [5] In some embodiments, in the simple cycle gas turbine plant according to any one of [2] to [4] above, the parameter is a rotation speed of the gas turbine; The control device is configured to start the small air volume operation mode when the rotation speed of the gas turbine exceeds a first threshold value that is smaller than the rotation speed corresponding to the ignition timing of the combustor, and to switch from the small air volume operation mode to the rated operation mode when the rotation speed of the gas turbine exceeds a second threshold value that is larger than the rotation speed corresponding to the ignition timing.

[0064] According to the simple cycle gas turbine plant described in [5] above, the rotational speed that is normally monitored in a typical gas turbine can be used as the parameter to obtain the effects described in any of [2] to [4] above.

[0065] [6] In some embodiments, in the simple cycle gas turbine plant described in [2] above, the parameter is the outlet pressure of the gas turbine (e.g., the pressure Ph mentioned above); The control device is configured to start the blower fan and initiate the small air volume operation mode when the outlet pressure of the gas turbine falls below a first threshold value (for example, the above-mentioned first threshold value Ph1).

[0066] According to the simple cycle gas turbine plant described in [6] above, the outlet pressure of the gas turbine can be used as the parameter to obtain the effect described in [2] above.

[0067] [7] In some embodiments, in the simple cycle gas turbine plant described in [6] above, the control device is configured to be able to execute a rated operation mode in which the blower fan is operated at a rated air volume; The control device is configured to switch from the small air volume operation mode to the rated operation mode when the outlet pressure of the gas turbine falls below a second threshold (for example, the above-mentioned second threshold Ph2) that is lower than the first threshold.

[0068] According to the simple cycle gas turbine plant described in [7] above, the outlet pressure of the gas turbine can be used as the parameter to obtain the effect described in [5] above.

[0069] [8] In some embodiments, in the simple cycle gas turbine plant according to any one of [1] to [7] above, The control device is configured to operate the blower fan at an air volume that is 10% to 50% of a rated air volume in the small air volume operation mode.

[0070] According to the simple cycle gas turbine plant described in [8] above, the effects described in [1] to [7] above can be enhanced by setting the air volume of the blower fan to an appropriate volume.

[0071] [9] In some embodiments, in the simple cycle gas turbine plant according to any one of [1] to [8] above, The denitration device is a selective catalytic reduction denitration device.

[0072] According to the simple cycle gas turbine plant described in [9] above, it is possible to obtain the effects described in any one of [1] to [8] above.

[0073]

[10] A method of operating a simple cycle gas turbine plant (e.g., the simple cycle gas turbine plant 2 described above) according to at least one embodiment of the present disclosure includes: a gas turbine (e.g., gas turbine 4 described above); an exhaust gas line (for example, the above-mentioned exhaust gas line 8) through which exhaust gas from the gas turbine flows; a denitration device (for example, the above-mentioned denitration device 10) provided in the exhaust gas line; a blower fan (for example, the above-mentioned blower fan 32) for blowing cooling air; a cooling air line (for example, the above-mentioned cooling air line 34) configured to supply the cooling air from the blower fan to a position in the exhaust gas line upstream of the denitration device; A method for operating a simple cycle gas turbine plant comprising: The operating method includes a step of controlling the blower fan based on a parameter related to an exhaust gas flow rate of the gas turbine, and executing a low air volume operation mode in which the blower fan is operated at an air volume less than a rated air volume during at least a portion of a startup period of the gas turbine.

[0074] According to the operation method of the simple cycle gas turbine plant described in

[10] above, by supplying cooling air from the blower fan via a cooling air line to a position in the exhaust gas line upstream of the denitration device, the temperature of the exhaust gas flowing into the denitration device can be lowered, thereby suppressing damage to the denitration device. Furthermore, by operating the blower fan at a low airflow rate (lower than the rated airflow rate) during at least a portion of the startup period of the gas turbine, an increase in exhaust gas pressure loss at the turbine outlet side of the gas turbine can be suppressed compared to when the blower fan is always operated at the rated airflow rate during startup. This suppresses a pressure increase downstream of the turbine's last-stage rotor blades during at least a portion of the startup period of the gas turbine. This prevents gas that has passed through the last-stage rotor blades from flowing into the inside of the hub via the grooves on the outer peripheral surface of the hub, thereby reducing the risk of damage to the inside of the hub due to heating.

[0075]

[11] In some embodiments, in the method for operating a simple cycle gas turbine plant according to

[10] above, In the step, the blower fan is started and the small air volume operation mode is initiated after the rotor of the gas turbine starts to rotate and before ignition of the combustor of the gas turbine.

[0076] During startup of a gas turbine, the turbine exhaust pressure decreases as the gas turbine rotation speed increases. Therefore, if the blower fan is started at or before the start of rotation of the gas turbine rotor, a period in which the pressure near the outer circumferential surface of the hub downstream of the turbine's last-stage rotor blades becomes positive is likely to occur, and gas that has passed through the turbine's last-stage rotor blades is likely to flow into the inside of the hub via the grooves in the outer circumferential surface of the hub. Therefore, by starting the blower fan and entering the small air volume operation mode after the start of rotation of the gas turbine rotor as described in

[11] above, a period in which the pressure near the outer circumferential surface of the hub downstream of the turbine's last-stage rotor blades becomes positive is unlikely to occur, and gas that has passed through the turbine's last-stage rotor blades is prevented from flowing into the inside of the hub via the grooves in the outer circumferential surface of the hub. This reduces the risk of damage to the inside of the hub due to overheating.

[0077] Furthermore, if the timing for starting the blower fan and initiating the small air volume operation mode is set after the timing for igniting the combustor, there is a possibility that a period will occur during which the high-temperature exhaust gas from the gas turbine flows into the denitration device without being cooled by the blower fan, which is likely to cause damage to the denitration device. Therefore, by setting the timing for starting the blower fan and initiating the small air volume operation mode before ignition of the combustor as described above in

[11] , it is possible to prevent the high-temperature exhaust gas from the gas turbine from flowing into the denitration device without being cooled by the blower fan, thereby suppressing damage to the denitration device.

[0078]

[12] In some embodiments, in the method for operating a simple cycle gas turbine plant described in

[11] above, the parameter is the rotational speed of the gas turbine (for example, the rotational speed N mentioned above), In this step, when the rotation speed of the gas turbine exceeds a first threshold value (e.g., the first threshold value N1 described above) that is smaller than the rotation speed corresponding to the ignition timing of the combustor (e.g., the ignition rotation speed Ni described above), the blower fan is started and the small air volume operation mode is initiated.

[0079] According to the operation method of the simple cycle gas turbine plant described in

[12] above, the rotational speed that is normally monitored in a typical gas turbine can be used as the parameter to obtain the effect described in

[11] above.

[0080]

[13] In some embodiments, in the method for operating a simple cycle gas turbine plant according to

[12] above, In the step, when the rotation speed of the gas turbine exceeds a second threshold value that is greater than the rotation speed corresponding to the ignition timing, the operation mode is switched from the small air volume operation mode to a rated operation mode in which the blower fan is operated at a rated air volume.

[0081] According to the operation method of the simple cycle gas turbine plant described in

[13] above, after ignition of the combustor, the high-temperature exhaust gas from the gas turbine can be appropriately cooled by the blower fan, thereby suppressing damage to the denitration device.

[0082]

[14] In some embodiments, in the method for operating a simple cycle gas turbine plant described in

[11] above, the parameter is the outlet pressure of the gas turbine (e.g., the pressure Ph mentioned above); In the step, when the outlet pressure of the gas turbine falls below a first threshold value (for example, the above-mentioned first threshold value Ph1), the blower fan is started and the small air volume operation mode is initiated.

[0083] According to the method for operating a simple cycle gas turbine plant described in

[14] above, by appropriately setting the first threshold value, the outlet pressure of the gas turbine can be used as the parameter to obtain the effect described in

[11] above.

[0084]

[15] In some embodiments, in the method of operating a simple cycle gas turbine plant described in

[14] above, In this step, when the outlet pressure of the gas turbine falls below a second threshold (for example, the above-mentioned second threshold Ph2) that is smaller than the first threshold, the operation mode is switched from the small air volume operation mode to a rated operation mode in which the blower fan is operated at a rated air volume.

[0085] According to the operation method of the simple cycle gas turbine plant described in

[15] above, by appropriately setting the second threshold value, the high-temperature exhaust gas from the gas turbine can be appropriately cooled by the blower fan after ignition of the combustor, thereby suppressing damage to the denitration device. [Explanation of symbols]

[0086] 2 Simple cycle gas turbine plant 4. Gas turbine 5 Starting motor 6. Generator 8 Exhaust gas line 9 rotor 10 Denitration equipment 12 Chimney 14 Tachometer 20 Compressor 22 Combustor 24 Turbine 25 Rotation axis 32 Blower fan 34 Cooling air line 38 Last stage rotor blade 38a Airfoil 38b Platform section 40 Exhaust compartment 41 Cabin wall 42 Bearing box 43 Diffuser outer wall 44 Diffuser passage 44A Diffuser inlet 45 Diffuser inner wall 46 Bulkhead 47 Bearings 49 Gap 50 strut 51 Strut cover 53 Hub 54 Outer surface 55 Pressure gauge 90 Control device 91 processors 92 RAM 93 ROM 94 HDD 95 Bus 96 Input I / F 98 Output I / F 412 Intake 481 1st cooling passage 482 2nd cooling passage 483 Third cooling passage

Claims

1. A gas turbine, an exhaust gas line through which exhaust gas from the gas turbine flows; a denitration device provided in the exhaust gas line; a blower fan for supplying cooling air; a cooling air line configured to supply the cooling air from the blower fan to a position in the exhaust gas line upstream of the denitration device; a control device configured to control the blower fan based on a parameter related to an exhaust gas flow rate of the gas turbine; and Equipped with the control device is configured to execute a small air volume operation mode in which the blower fan is operated at an air volume less than a rated air volume during at least a portion of a startup period of the gas turbine.

2. 2. The simple cycle gas turbine plant according to claim 1, wherein the control device is configured to start the blower fan and initiate the small air volume operation mode after a rotor of the gas turbine starts to rotate and before ignition of a combustor of the gas turbine.

3. the parameter is a rotation speed of the gas turbine; 3. The simple cycle gas turbine plant according to claim 2, wherein the control device is configured to start the blower fan and initiate the small air volume operation mode when the rotation speed of the gas turbine exceeds a first threshold value that is lower than a rotation speed corresponding to an ignition timing of the combustor.

4. the control device is configured to be able to execute a rated operation mode in which the blower fan is operated at a rated air volume; 3. The simple cycle gas turbine plant according to claim 2, wherein the control device is configured to switch from the small volume operation mode to the rated operation mode after a rotor of the gas turbine starts to rotate and after a combustor of the gas turbine is ignited.

5. the parameter is a rotation speed of the gas turbine; 5. The simple cycle gas turbine plant according to claim 4, wherein the control device is configured to start the blower fan and initiate the small air volume operation mode when the rotation speed of the gas turbine exceeds a first threshold value that is smaller than the rotation speed corresponding to an ignition timing of the combustor, and to switch from the small air volume operation mode to the rated operation mode when the rotation speed of the gas turbine exceeds a second threshold value that is larger than the rotation speed corresponding to the ignition timing.

6. the parameter is an outlet pressure of the gas turbine; 3. The simple cycle gas turbine plant according to claim 2, wherein the control device is configured to start the blower fan and initiate the small air volume operation mode when the outlet pressure of the gas turbine falls below a first threshold value.

7. the control device is configured to be able to execute a rated operation mode in which the blower fan is operated at a rated air volume; 7. The simple cycle gas turbine plant according to claim 6, wherein the control device is configured to switch from the small volume operation mode to the rated operation mode when the outlet pressure of the gas turbine falls below a second threshold value that is lower than the first threshold value.

8. 2. The simple cycle gas turbine plant according to claim 1, wherein the control device is configured to operate the blower fan at an air volume that is 10% to 50% of a rated air volume in the small air volume operation mode.

9. The simple cycle gas turbine plant according to claim 1 , wherein the denitration device is a selective catalytic reduction denitration device.

10. A gas turbine, an exhaust gas line through which exhaust gas from the gas turbine flows; a denitration device provided in the exhaust gas line; a blower fan for supplying cooling air; a cooling air line configured to supply the cooling air from the blower fan to a position in the exhaust gas line upstream of the denitration device; A method for operating a simple cycle gas turbine plant comprising: a step of controlling the blower fan based on a parameter related to an exhaust gas flow rate of the gas turbine, and executing a low air volume operation mode in which the blower fan is operated at an air volume less than a rated air volume during at least a part of a startup period of the gas turbine.

11. 11. The method for operating a simple cycle gas turbine plant according to claim 10, wherein in the step, the blower fan is started and the small air volume operation mode is initiated after a rotor of the gas turbine starts to rotate and before ignition of a combustor of the gas turbine.

12. the parameter is a rotation speed of the gas turbine; 12. The method for operating a simple cycle gas turbine plant according to claim 11, wherein, in the step, when the rotation speed of the gas turbine exceeds a first threshold value that is smaller than a rotation speed corresponding to an ignition timing of the combustor, the blower fan is started and the small air volume operation mode is initiated.

13. 13. The simple cycle gas turbine plant according to claim 12, wherein, in the step, when the rotation speed exceeds a second threshold value that is greater than the rotation speed corresponding to the ignition timing, the operation mode is switched from the small air volume operation mode to a rated operation mode in which the blower fan is operated at a rated air volume.

14. the parameter is an outlet pressure of the gas turbine; 12. The method for operating a simple cycle gas turbine plant according to claim 11, wherein, in the step, when the outlet pressure of the gas turbine falls below a first threshold value, the blower fan is started and the small air volume operation mode is initiated.

15. 15. The simple cycle gas turbine plant according to claim 14, wherein, in the step, when the outlet pressure of the gas turbine falls below a second threshold value that is lower than the first threshold value, the operation mode is switched from the small air volume operation mode to a rated operation mode in which the blower fan is operated at a rated air volume.

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