Gas turbine system and gas turbine system control method

Abstract

This prevents leakage of lubricating oil sealed in the bearings located in the exhaust chamber during a sudden load reduction operation of a gas turbine. [Solution] The gas turbine system according to the present invention comprises a gas turbine, a heat recovery device for recovering waste heat from the exhaust gas of the gas turbine, a blower for supplying the exhaust gas of the heat recovery device, and a carbon dioxide recovery device for recovering carbon dioxide from the exhaust gas. The exhaust chamber of a gas turbine houses a bearing section that rotatably supports the gas turbine rotor. Sealing air is supplied to the bearing section by a sealing air supply system. If the gas turbine's operating state is determined to be a sudden load reduction operation, the sealing air supply system is controlled to increase the flow rate of sealing air compared to the gas turbine's normal operation.

Description

Technical Field

[0001] The present disclosure relates to a gas turbine system and a method for controlling a gas turbine system.

Background Art

[0002] As a system using a gas turbine capable of driving a turbine with combustion gas generated by combustion of fuel as a working fluid, a gas turbine system capable of improving the energy efficiency in the system is known by including a waste heat recovery device that recovers waste heat from exhaust gas (combustion gas) that has completed work in the turbine. For example, in a gas turbine combined cycle (GTCC) including a waste heat recovery boiler (HRSG: Heat Recovery Steam Generator) capable of generating steam using waste heat recovered from exhaust gas as a waste heat recovery device, by driving a steam turbine using the steam generated by waste heat, better energy efficiency can be obtained compared to a system of a single gas turbine.

[0003] In recent years, in order to reduce carbon dioxide emitted into the atmosphere, a gas turbine system including a carbon dioxide recovery device for recovering carbon dioxide contained in the exhaust gas of a gas turbine has been developed. For example, in Patent Document 1, a gas turbine system including a carbon dioxide recovery device capable of recovering carbon dioxide from exhaust gas by bringing the exhaust gas of a gas turbine constituting a gas turbine combined cycle into contact with a liquid (absorbent liquid) having absorbency for carbon dioxide is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to recover gas turbine exhaust gases with a carbon dioxide recovery system, it is necessary to supply the carbon dioxide recovery system with the exhaust gases at the required pressure. For this reason, a blower is sometimes installed upstream of the carbon dioxide recovery system to supply gas turbine exhaust gases at a predetermined pressure. The operation of this blower is variably controlled according to the operating state of the gas turbine, but if a sudden load reduction operation occurs where the load on the gas turbine suddenly decreases, the operation of the blower may not be able to adequately follow the sudden decrease in the gas turbine exhaust gas flow rate, and negative pressure may act on the exhaust chamber upstream of the blower. Since the bearing section that rotatably supports the gas turbine rotor is located in this exhaust chamber, the negative pressure acting on the exhaust chamber may cause the lubricating oil sealed in the bearing section to leak.

[0006] At least one embodiment of this disclosure has been made in view of the above circumstances and aims to provide a gas turbine system and a gas turbine system control method that can prevent leakage of lubricating oil sealed in a bearing located in the exhaust chamber during a sudden load reduction operation of the gas turbine. [Means for solving the problem]

[0007] A gas turbine system according to at least one embodiment of this disclosure solves the above problems. Gas turbine and A heat recovery device for recovering waste heat contained in the exhaust gas of the aforementioned gas turbine, A blower for sending the exhaust gas from which the exhaust heat has been recovered by the exhaust heat recovery device, A carbon dioxide recovery device for recovering carbon dioxide from the exhaust gas sent by the blower, A bearing portion is installed in the exhaust chamber through which the exhaust gas flows between the gas turbine and the heat recovery device, and which rotatably supports the rotor of the gas turbine. A sealing air supply system for supplying sealing air to the bearing portion, An operating state determination unit for determining the operating state of the gas turbine, Based on the determination result of the operating state, a seal air control unit for controlling the seal air supply system, Equipped with, If the operating state determination unit determines that the operating state is a load reduction operation in which the load of the gas turbine changes at a rate of decrease of a standard value or more, the seal air control unit controls the seal air supply system so that the flow rate of the seal air increases compared to when the gas turbine is in normal operation.

[0008] A gas turbine system control method according to at least one embodiment of this disclosure solves the above problems. Gas turbine and A heat recovery device for recovering waste heat contained in the exhaust gas of the aforementioned gas turbine, A blower for sending the exhaust gas from which the exhaust heat has been recovered by the exhaust heat recovery device, A carbon dioxide recovery device for recovering carbon dioxide from the exhaust gas sent by the blower, A bearing portion is installed in the exhaust chamber through which the exhaust gas flows between the gas turbine and the heat recovery device, and which rotatably supports the rotor of the gas turbine. A sealing air supply system for supplying sealing air to the bearing portion, A gas turbine system control method for controlling a gas turbine system comprising: A step of determining the operating state of the gas turbine, A step of controlling the seal air supply system based on the result of determining the operating state, Equipped with, If the operating state is determined to be a rapid load reduction operation in which the load of the gas turbine changes at a rate of decrease exceeding a standard value, the seal air supply system is controlled to increase the flow rate of the seal air compared to the normal operation of the gas turbine. [Effects of the Invention]

[0009] According to at least one embodiment of the present disclosure, it is possible to provide a gas turbine system capable of preventing leakage of lubricating oil enclosed in a bearing portion disposed in an exhaust chamber during a load rejection operation of a gas turbine, and a method for controlling the gas turbine system.

Brief Description of the Drawings

[0010] [Figure 1] It is an overall configuration diagram of a gas turbine system according to an embodiment. [Figure 2] It is an enlarged cross-sectional view of a bearing portion provided in the exhaust chamber of FIG. 1. [Figure 3] It is a block configuration diagram of a control device for controlling the gas turbine system of FIG. 1. [Figure 4] It is a diagram showing an operating state during a load rejection operation of a seal air supply system of FIG. 2. [Figure 5] It is a flowchart showing a method for controlling a gas turbine system implemented by the control device of FIG. 4. [Figure 6A] It is a modification of FIG. 2. [Figure 6B] It is another modification of FIG. 2.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the configurations described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0012] FIG. 1 is an overall configuration diagram of a gas turbine system 1 according to an embodiment, and FIG. 2 is an enlarged cross-sectional view of a bearing portion 20 provided in an exhaust chamber 16 of FIG. 1. The gas turbine system 1 includes a gas turbine 2, a waste heat recovery device 4, a blower 6, and a carbon dioxide recovery device 8.

[0013] The gas turbine 2 includes a compressor 10, a combustor 12, a turbine 14, and an exhaust chamber 16. The compressor 10 compresses the external air taken in from the air intake to generate compressed air as combustion air. In the compressor compartment of the compressor 10, a plurality of stationary blades are provided, which are alternately arranged so as to correspond to the plurality of moving blades provided on the compressor rotor 10a. As the compressor rotor 10a rotates, the external air taken in from the air intake is gradually compressed toward the downstream side. Also, an extraction line 11 for extracting a part of the compressed air is provided in the intermediate stage of the compressor 10 (a part of the compressed air extracted through the extraction line 11 can be used as seal air As supplied to the bearing portion 20, as will be described later).

[0014] The combustor 12 generates high-temperature and high-pressure combustion gas by mixing and burning the compressed air generated by the compressor 10 with fuel supplied from a fuel supply system (not shown). The turbine 14 outputs power by driving the turbine rotor 14a using the combustion gas generated by the combustor 12 as a working fluid. When a generator is connected to the turbine rotor 14a, power generation is performed by driving the generator by the output of the turbine 14.

[0015] The combustion gas that has completed its work in the turbine 14 is discharged as exhaust gas into the exhaust chamber 16 provided on the downstream side of the turbine 14.

[0016] The aforementioned compressor rotor 10a and turbine rotor 14a are coaxially connected to each other to integrally form a gas turbine rotor (hereinafter, appropriately referred to as "rotor 18"). One end side of the rotor 18 is provided so as to penetrate the central portion of the exhaust chamber 16, and is rotatably supported by a bearing portion 20 provided in the exhaust chamber 16 (the other end side of the rotor 18 is also rotatably supported by a bearing portion not shown).

[0017] The specific configuration of the bearing section 20 will now be described with reference to Figure 2. In the bearing section 20, the rotor 18 is rotatably supported by the bearing housing 24 via the journal bearing 22. Lubricating oil is supplied to the journal bearing 22. Four seal rings 26, 28, 30, and 32 are arranged at predetermined intervals at the end of the bearing housing 24. Seal members 26a, 28a, 30a, and 32a are provided on the inner circumference of each seal ring 26, 28, 30, and 32, respectively.

[0018] A sealing air supply hole 34 opening to the sealing surface is formed radially in the centrally located sealing ring 28. A sealing air supply system 50 for supplying sealing air As is connected to the sealing air supply hole 34. The sealing air supply system 50 includes a sealing air supply line 52. One end of the sealing air supply line 52 is connected to an extraction line 11 (see Figure 1) provided in the compressor 10, and the other end is connected to the sealing air supply hole 34, thereby supplying compressed air generated by the compressor 10 as sealing air As to the sealing air supply hole 34.

[0019] Furthermore, in the sealing air supply system 50, if compressed air generated by the compressor 10 cannot be obtained as sealing air As, air supplied from another air supply source may be supplied as sealing air As. In this case, the other air supply source can be an air supply source located inside or outside the plant where the gas turbine system 1 is installed, and may be a configuration such as compressed air used within the plant or compressed air cylinders.

[0020] The seal air supply system 50 also includes a bypass line 54 that bypasses a portion of the seal air supply line 52, and a flow control valve 56 provided on the bypass line 54. The bypass line 54 is configured to bypass the space between the upstream and downstream sides of the orifice 53 provided on the seal air supply line 52. The flow control valve 56 is a valve whose opening degree can be adjusted according to the operating state of the gas turbine 2. As will be described later, the flow control valve 56 is in a fully closed state during normal operation of the gas turbine 2, but if it is determined that the gas turbine 2 has performed a sudden load reduction operation, the flow control valve 56 can be opened to increase the amount of seal air As supplied compared to normal operation.

[0021] Returning to Figure 1, the waste heat recovery device 4 is configured to recover waste heat contained in the exhaust gas of the gas turbine 2. The waste heat recovery device 4 is a heat exchanger in which high-temperature exhaust gas can exchange heat with a heat transfer medium. For example, it is configured such that the exhaust gas flowing through the heat transfer tube section constituting the heat exchanger exchanges heat with the heat transfer medium. Specifically, the waste heat recovery device 4 may be a heat recovery steam generator (HRSG) capable of generating steam using the waste heat recovered from the exhaust gas. In this case, the waste heat recovery device 4 generates high-temperature steam by heating the heat transfer medium using the waste heat recovered from the exhaust gas. The high-temperature steam generated in the waste heat recovery device 4 can be used as the working fluid for a steam turbine (not shown) or as a heat source for the heating and separation process in the second tank 64 of the carbon dioxide recovery device 8 described later.

[0022] The blower 6 is configured to send the exhaust gas, from which heat has been recovered by the heat recovery device 4, to the carbon dioxide recovery device 8. In the heat recovery device 4, as described above, heat is recovered as the exhaust gas from the turbine 14 passes through the heat transfer tube section that constitutes the heat exchanger, but pressure loss occurs when passing through the heat transfer tube section. Therefore, by operating the blower 6 installed downstream of the heat recovery device 4, the exhaust gas that has passed through the heat recovery device 4 can be suitably sent to the carbon dioxide recovery device 8 located further downstream. Since the amount of exhaust gas discharged from the gas turbine 2 depends on the operating state of the gas turbine 2, the amount of air blown by the blower 6 is also variably controlled based on the operating state of the gas turbine 2.

[0023] The carbon dioxide recovery device 8 is configured to recover carbon dioxide from exhaust gas sent by the blower 6. The carbon dioxide recovery method employed by the carbon dioxide recovery device 8 is not limited, but in this embodiment, the case in which a chemical absorption method is employed will be described as an example. In the chemical absorption method, good recovery efficiency can be obtained when the concentration of carbon dioxide in the exhaust gas is relatively low (around a few percent to a little over ten percent) and the pressure of the exhaust gas is approximately equal to or lower than atmospheric pressure.

[0024] In the carbon dioxide recovery device 8 of this embodiment, the exhaust gas sent from the blower 6 is first brought into contact with an amine-based absorbent liquid (lean absorbent liquid) in the first tank 60. In the first tank 60, the lean absorbent liquid is supplied from an absorbent liquid supply unit 62 located at the top so as to fall downwards, and the exhaust gas from the blower 6 is supplied to the falling lean absorbent liquid, thereby bringing the exhaust gas and the lean absorbent liquid into contact. The lean absorbent liquid absorbs carbon dioxide contained in the exhaust gas, becoming a rich absorbent liquid, which accumulates at the bottom of the first tank 60.

[0025] Furthermore, the remaining exhaust gas, from which carbon dioxide has been absorbed by contact with the lean absorbent liquid in the first tank 60, is released to the outside through the exhaust tower 65.

[0026] The rich absorbent liquid accumulated at the bottom of the first tank 60 is sent to the second tank 64. In the second tank 64, carbon dioxide is separated from the rich absorbent liquid by a heating separation reaction. The heating separation reaction in the second tank 64 requires heating the rich absorbent liquid, and as a heat source, the waste heat recovered by the waste heat recovery device 4 (or high-temperature steam if the waste heat recovery device 4 is configured as a waste heat recovery boiler) can be used. The carbon dioxide separated in the second tank 64 is recovered by the carbon dioxide recovery unit 66. The absorbent liquid from which carbon dioxide has been separated by the heating separation treatment in the second tank 64 returns to the lean absorbent liquid and is circulated back to the first tank 60.

[0027] In the gas turbine system 1 having the above configuration, the amount of exhaust gas discharged from the turbine 14 changes based on the operating state of the gas turbine 2. Therefore, the amount of operation of the blower 6, which sends the exhaust gas that has passed through the heat recovery device 4 to the carbon dioxide recovery device 8, is controlled according to the amount of exhaust gas. If a sudden load reduction operation is performed, which causes a sudden decrease in the load of the gas turbine 2, the amount of exhaust gas discharged from the turbine 14 also decreases rapidly due to the rapid load change of the gas turbine 2. However, the operation control of the blower 6 may not be able to adequately follow such a rapid change in the amount of exhaust gas discharged, and negative pressure may act on the exhaust chamber 16 located upstream of the blower 6. As mentioned above, the exhaust chamber 16 has a bearing section 20 that rotatably supports the rotor 18, so if negative pressure acts on it, there is a risk of leakage of lubricating oil sealed in the bearing section 20. Such problems can be suitably solved by the gas turbine system control method implemented by the control device 100 described below.

[0028] The control device 100 is a control unit for controlling the gas turbine system 1 having the above configuration, and is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example, and the CPU reads this program into the RAM and performs information processing and calculations to realize the various functions. The program may be pre-installed in the ROM or other storage medium, provided in a state where it is stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memory, etc.

[0029] Figure 3 is a block diagram of the control device 100 for controlling the gas turbine system 1 shown in Figure 1. The control device 100 comprises an operating state determination unit 102 and a seal air control unit 104.

[0030] The operating state determination unit 102 is configured to determine the operating state of the gas turbine 2. In this embodiment, the operating state to be determined by the operating state determination unit 102 is a load reduction operation in which the load of the gas turbine 2 changes at a rate of decrease equal to or greater than a reference value.

[0031] The determination of a sudden load reduction operation by the operating state determination unit 102 may be performed by directly detecting the load of the gas turbine 2 and comparing the rate of load reduction, which is determined from its temporal change, with a reference value, or it may be performed based on a control signal generated when a sudden load reduction operation is performed. For example, in the control device 100, when a predetermined event occurs in the gas turbine system 1 that requires a sudden load reduction operation, a load shedding operation signal or a runback signal is received to perform corresponding control involving a sudden load reduction operation. Therefore, when the operating state determination unit 102 receives a control signal indicating a sudden load reduction operation, such as a load shedding operation signal or a runback signal, it can determine that a sudden load reduction operation has been performed in the gas turbine 2. By determining the sudden load reduction operation based on the control signal received at the time of the sudden load reduction operation in this way, the sudden load reduction operation can be determined earlier compared to when the load of the gas turbine 2 is directly detected and determined, and good responsiveness can be obtained.

[0032] The seal air control unit 104 is configured to control the seal air As supplied by the seal air supply system 50. When the gas turbine 2 is in a normal operating state (not a sudden load reduction operation), the seal air supply system 50 controls the flow control valve 56 to a fully closed state, as shown in Figure 2, so that the seal air As is supplied to the bearing section 20 only through the seal air supply line 52 without passing through the bypass line 54. In this case, the seal air is supplied to the bearing section 20 at a predetermined constant flow rate, taking into account the flow resistance of the seal air supply line 52 and the pressure loss in the orifice 53.

[0033] On the other hand, if the operating state determination unit 102 determines that a sudden load reduction operation has occurred, the seal air control unit 104 controls the seal air supply system 50 so that the flow rate of seal air As increases compared to the normal operating state. Specifically, as shown in Figure 4, the seal air control unit 104 increases the flow cross-sectional area of ​​the seal air As flow path in the seal air supply system 50 by opening the flow control valve 56, which was in a fully closed state in the normal operating state, thereby increasing the flow rate of seal air As supplied to the bearing section 20. In this way, when a sudden load reduction operation is performed in the gas turbine 2, the increase in seal air As supplied to the bearing section 20 effectively prevents leakage of lubricating oil sealed in the bearing section 20, even when negative pressure is applied to the exhaust chamber 16.

[0034] Next, a gas turbine system control method implemented by the control device 100 having the above configuration will be described. Figure 5 is a flowchart showing the gas turbine system control method implemented by the control device 100 of Figure 4.

[0035] First, the gas turbine 2 is controlled to its normal operating state as an initial state (step S1). In the normal operating state, the load on the gas turbine 2 is controlled to be approximately constant. At this time, the seal air control unit 104 controls the seal air supply system 50 by switching the flow control valve 56 to the fully closed state as shown in Figure 2, so that the seal air As is supplied to the bearing section 20 only through the seal air supply line 52 without passing through the bypass line 54.

[0036] Next, the operating state determination unit 102 monitors the operating state of the gas turbine 2 to determine whether or not a load reduction operation has been performed (step S2). As mentioned above, the determination in step S2 is based on whether or not a control signal (at least one of the load cutoff operation signal or the runback signal) generated when a load reduction operation is performed has been received.

[0037] If the operating state determination unit 102 determines that a sudden load reduction operation has been performed (step S2: YES), the seal air control unit 104 controls the seal air supply system 50 so that the flow rate of seal air As increases compared to the normal operating state (step S3). In step S3, as described above with reference to Figure 4, the seal air control unit 104 opens the flow rate control valve 56 in the seal air supply system 50, which is in a fully closed state in the normal operating state, thereby increasing the flow rate of seal air As by increasing the cross-sectional area of ​​the flow path of seal air As. In this way, when a sudden load reduction operation is performed in the gas turbine 2, the amount of seal air As supplied to the bearing section 20 located in the exhaust chamber 16 is increased, which effectively prevents leakage of lubricating oil sealed in the bearing section 20 due to the negative pressure acting in the exhaust chamber 16.

[0038] This control of increasing the seal air As continues as long as the negative pressure state in the exhaust chamber persists, or for a certain period of time set in advance by a timer (Step S4: NO). When the rapid load reduction operation is completed (Step S4: YES), the process proceeds to Step S1, and the operating state of the gas turbine 2 returns to the normal operating state.

[0039] Figure 6A is a modified version of Figure 2. In this modified version, the orifice 53 provided on the seal air supply line 52 in the seal air supply system 50 is configured as a variable orifice, and the bypass line 54 and flow control valve 56 are omitted compared to the embodiment shown in Figure 2.

[0040] In the modified configuration shown in Figure 6A, the seal air control unit 104 can adjust the amount of seal air As supplied to the bearing section 20 by changing the flow path cross-sectional area of ​​the orifice 53. Therefore, if the operating state determination unit 102 determines that a sudden load reduction operation has not been performed (i.e., it is in a normal operating state), the seal air control unit 104 controls the amount of seal air As supplied to the bearing section 20 to correspond to the normal operating state by decreasing the flow path cross-sectional area of ​​the orifice 53. On the other hand, if the operating state determination unit 102 determines that a sudden load reduction operation has been performed, the seal air control unit 104 controls the amount of seal air As supplied to the bearing section 20 to be higher than in the normal operating state by increasing the flow path cross-sectional area of ​​the orifice 53.

[0041] Figure 6B shows another modification of Figure 2. In the modification shown in Figure 6B, a flow control valve 57 is provided instead of the variable orifice 53 in the modification of Figure 6A. In this modification, by adjusting the opening degree of the flow control valve 57, the amount of sealing air As supplied can be increased during a sudden load reduction operation compared to the normal operating state, similar to the configurations described above.

[0042] Accordingly, in the modified examples shown in Figures 6A and 6B, the configuration of the seal air supply system 50 is simplified compared to the previously described embodiment. However, similar to the previously described embodiment, when a sudden load reduction operation is performed in the gas turbine 2, the amount of seal air As supplied to the bearing portion 20 located in the exhaust chamber 16 is increased, thereby effectively preventing leakage of lubricating oil sealed in the bearing portion 20 due to the negative pressure acting on the exhaust chamber 16.

[0043] Furthermore, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, without departing from the spirit of this disclosure, and the above-described embodiments may also be combined as appropriate.

[0044] The contents described in each of the above embodiments can be understood, for example, as follows:

[0045] (1) A gas turbine system according to one embodiment is: Gas turbine and A heat recovery device for recovering waste heat contained in the exhaust gas of the aforementioned gas turbine, A blower for sending the exhaust gas from which the exhaust heat has been recovered by the exhaust heat recovery device, A carbon dioxide recovery device for recovering carbon dioxide from the exhaust gas sent by the blower, A bearing portion is installed in the exhaust chamber through which the exhaust gas flows between the gas turbine and the heat recovery device, and which rotatably supports the rotor of the gas turbine. A sealing air supply system for supplying sealing air to the bearing portion, An operating state determination unit for determining the operating state of the gas turbine, Based on the determination result of the operating state, a seal air control unit for controlling the seal air supply system, Equipped with, If the operating state determination unit determines that the operating state is a load reduction operation in which the load of the gas turbine changes at a rate of decrease of a standard value or more, the seal air control unit controls the seal air supply system so that the flow rate of the seal air increases compared to when the gas turbine is in normal operation.

[0046] According to the embodiment of (1) above, when the gas turbine load is rapidly reduced, the amount of sealing air supplied to the bearing located in the exhaust chamber is increased compared to normal operation. As a result, even when the blower's operating state cannot keep up with the load change of the gas turbine during a rapidly reduced load operation and negative pressure is applied to the exhaust chamber, leakage of lubricating oil sealed in the bearing located in the exhaust chamber can be effectively prevented.

[0047] (2) In other embodiments, in the embodiment of (1) above, The operating state determination unit determines that the gas turbine is in the load reduction operation when it receives at least one of a load cutoff signal or a runback signal.

[0048] According to the embodiment of (2) above, it is possible to determine that the operating state of the gas turbine is a rapid load reduction operation, provided that at least one of the load shedding signal or the runback signal is received. This allows for earlier determination of a rapid load reduction operation compared to directly detecting the load of the gas turbine and determining the rapid load reduction operation from its rate of change, thereby achieving better responsiveness.

[0049] (3) In other embodiments, in the embodiment of (1) or (2) above, The aforementioned sealing air supply system is A sealing air supply line for supplying the sealing air to the bearing portion, A bypass line configured to partially bypass the aforementioned seal air supply line, A flow control valve is provided in the bypass line, Equipped with, The seal air control unit controls the flow rate of the seal air supplied to the bearing by adjusting the opening degree of the flow rate control valve.

[0050] According to the embodiment of (3) above, a bypass line is provided in the seal air supply line of the seal air supply system to partially bypass it. A flow control valve is provided in the bypass line, and by adjusting the opening degree of the flow control valve, the cross-sectional area of ​​the flow path of the seal air can be varied, and the amount of seal air supplied to the bearing can be suitably controlled.

[0051] (4) In other embodiments, in the embodiment of (1) or (2) above, The aforementioned sealing air supply system is A sealing air supply line for supplying the sealing air to the bearing portion, A variable orifice provided in the aforementioned seal air supply line, Equipped with, The seal air control unit controls the flow rate of the seal air supplied to the bearing by changing the cross-sectional area of ​​the flow path of the variable orifice.

[0052] According to the embodiment of (4) above, a variable orifice is provided in the seal air supply line of the seal air supply system. The seal air control unit can suitably control the amount of seal air supplied to the bearing by changing the flow path cross-sectional area of ​​the variable orifice.

[0053] (5) In other embodiments, in the embodiment of (1) or (2) above, The aforementioned sealing air supply system is A sealing air supply line for supplying the sealing air to the bearing portion, A flow control valve provided in the aforementioned seal air supply line, Equipped with, The seal air control unit controls the flow rate of the seal air supplied to the bearing by changing the opening degree of the flow rate adjustment valve.

[0054] According to the embodiment of (5) above, a flow rate control valve is provided in the seal air supply line of the seal air supply system. The seal air control unit can suitably control the amount of seal air supplied to the bearing by changing the opening degree of the flow rate control valve.

[0055] (6) In other embodiments, in any one embodiment of (1) to (5) above, The sealing air supply system is configured to supply a portion of the compressed air supplied to the gas turbine as combustion air to the bearing section as sealing air.

[0056] According to the embodiment of (6) above, a portion of the compressed air generated by the compressor is extracted from the compressor as sealing air supplied to the bearing section.

[0057] (7) A gas turbine system control method according to one embodiment is: Gas turbine and A heat recovery device for recovering waste heat contained in the exhaust gas of the aforementioned gas turbine, A blower for sending the exhaust gas from which the exhaust heat has been recovered by the exhaust heat recovery device, A carbon dioxide recovery device for recovering carbon dioxide from the exhaust gas sent by the blower, A bearing portion is installed in the exhaust chamber through which the exhaust gas flows between the gas turbine and the heat recovery device, and which rotatably supports the rotor of the gas turbine. A sealing air supply system for supplying sealing air to the bearing portion, A gas turbine system control method for controlling a gas turbine system comprising: A step of determining the operating state of the gas turbine, A step of controlling the seal air supply system based on the result of determining the operating state, Equipped with, If the operating state is determined to be a rapid load reduction operation in which the load of the gas turbine changes at a rate of decrease exceeding a standard value, the seal air supply system is controlled to increase the flow rate of the seal air compared to the normal operation of the gas turbine.

[0058] According to the embodiment of (7) above, when the gas turbine load is rapidly reduced, the amount of sealing air supplied to the bearing located in the exhaust chamber is increased compared to normal operation. As a result, even when the blower's operating state cannot keep up with the load change of the gas turbine during a rapidly reduced load operation and negative pressure is applied to the exhaust chamber, leakage of lubricating oil sealed in the bearing located in the exhaust chamber can be effectively prevented. [Explanation of symbols]

[0059] 1. Gas Turbine System 2 Gas Turbines 4. Waste heat recovery system 6 Blower 8. Carbon dioxide capture device 10 Compressor 10a Compressor Rotor 11. Blowing line 12 Combustor 14 Turbine 14a Turbine rotor 16 Exhaust chamber 18 rotors 20 Bearing section 22 Journal bearings 24 Bearing housing 26, 28, 30, 32 sealing rings 26a, 28a, 30a, 32a sealing members 34 Seal air supply holes 50 Seal air supply system 52 Seal air supply line 53 Orifice 54 Bypass Line 56 Flow control valve 57 Flow control valve 60 Tank 1 62 Absorbent liquid supply unit 64 Tank 2 65 Exhaust Stack 66 Carbon Dioxide Capture Section 100 Control device 102 Operation status determination unit 104 Seal Air Control Unit As seal air

Claims

1. Gas turbine and A heat recovery device for recovering waste heat contained in the exhaust gas of the aforementioned gas turbine, A blower for sending the exhaust gas from which the exhaust heat has been recovered by the exhaust heat recovery device, A carbon dioxide recovery device for recovering carbon dioxide from the exhaust gas sent by the blower, A bearing portion is installed in the exhaust chamber through which the exhaust gas flows between the gas turbine and the heat recovery device, and which rotatably supports the rotor of the gas turbine. A sealing air supply system for supplying sealing air to the bearing portion, An operating state determination unit for determining the operating state of the gas turbine, Based on the determination result of the operating state, a seal air control unit for controlling the seal air supply system, Equipped with, A gas turbine system in which, when the operating state determination unit determines that the operating state is a load reduction operation in which the load of the gas turbine changes at a rate of decrease of a standard value or more, the seal air control unit controls the seal air supply system so that the flow rate of the seal air increases compared to when the gas turbine is in normal operation.

2. The gas turbine system according to claim 1, wherein the operating state determination unit determines that the gas turbine is in the load reduction operation when it receives at least one of a load cutoff signal or a runback signal.

3. The aforementioned sealing air supply system is A sealing air supply line for supplying the sealing air to the bearing portion, A bypass line configured to partially bypass the aforementioned seal air supply line, A flow control valve is provided in the bypass line, Equipped with, The gas turbine system according to claim 1 or 2, wherein the seal air control unit controls the flow rate of the seal air supplied to the bearing by adjusting the opening degree of the flow rate control valve.

4. The aforementioned sealing air supply system is A sealing air supply line for supplying the sealing air to the bearing portion, A variable orifice provided in the aforementioned seal air supply line, Equipped with, The gas turbine system according to claim 1 or 2, wherein the seal air control unit controls the flow rate of the seal air supplied to the bearing by changing the flow path cross-sectional area of ​​the variable orifice.

5. The aforementioned sealing air supply system is A sealing air supply line for supplying the sealing air to the bearing portion, A flow control valve provided in the aforementioned seal air supply line, Equipped with, The gas turbine system according to claim 1 or 2, wherein the seal air control unit controls the flow rate of the seal air supplied to the bearing by changing the opening degree of the flow rate control valve.

6. The gas turbine system according to claim 1 or 2, wherein the seal air supply system is configured to supply a portion of the compressed air supplied to the gas turbine as combustion air to the bearing as the seal air.

7. Gas turbine and A heat recovery device for recovering waste heat contained in the exhaust gas of the aforementioned gas turbine, A blower for sending the exhaust gas from which the exhaust heat has been recovered by the exhaust heat recovery device, A carbon dioxide recovery device for recovering carbon dioxide from the exhaust gas sent by the blower, A bearing portion is installed in the exhaust chamber through which the exhaust gas flows between the gas turbine and the heat recovery device, and which rotatably supports the rotor of the gas turbine. A sealing air supply system for supplying sealing air to the bearing portion, A gas turbine system control method for controlling a gas turbine system comprising: A step of determining the operating state of the gas turbine, A step of controlling the seal air supply system based on the result of determining the operating state, Equipped with, A gas turbine system control method, which, when it is determined that the operating state is a load reduction operation in which the load of the gas turbine changes at a rate of decrease greater than or equal to a reference value, controls the seal air supply system so that the flow rate of the seal air increases compared to when the gas turbine is in normal operation.

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