Combined cycle plant startup method, combined cycle plant startup control device, and combined cycle plant

Abstract

To shorten a startup time required at cold startup.SOLUTION: A combined cycle plant comprises: a gas turbine; an exhaust heat recovery boiler capable of generating steam using heat contained in exhaust gas from the gas turbine; and a steam turbine capable of being driven by the steam. The method relates to a method for starting up the combined cycle plant. When the gas turbine is started, after the rotation speed of the gas turbine reaches a reference rotation speed, the output of the gas turbine is controlled to be a first output for a predetermined period of time. After the predetermined period of time elapses, the output is controlled to become a second output which is less than the first output. When the temperature of the steam falls below a preset upper limit temperature, the supply of the steam to the steam turbine is started.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a combined cycle plant startup method, a combined cycle plant startup control device, and a combined cycle plant. [Background technology]

[0002] A combined cycle plant is known that improves energy efficiency by combining a gas turbine, a heat recovery boiler, and a steam turbine. In the combined cycle plant, the heat contained in the exhaust gas generated by driving the gas turbine is recovered in the heat recovery boiler, and steam is generated by the heat recovery boiler. The steam generated in the heat recovery boiler is supplied to the steam turbine to drive the steam turbine.

[0003] When starting up a combined cycle plant in a cold state, each element constituting the plant is controlled according to a startup control sequence. In the startup control sequence, the gas turbine is started first, and the rotation speed of the gas turbine is increased to a reference rotation speed (e.g., rated rotation speed), and then a predetermined initial load is applied to gradually increase the exhaust gas temperature of the gas turbine. When the exhaust gas temperature of the gas turbine has risen sufficiently to enable the heat recovery boiler to generate sufficient steam, the supply of steam to the steam turbine is started, thereby completing the startup control sequence.

[0004] For example, Patent Document 1 discloses that, during start-up of a combined cycle plant, the output of the gas turbine is maintained constant after the gas turbine has increased in speed until steam can be supplied to the steam turbine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2022-070960 Summary of the Invention [Problem to be solved by the invention]

[0006] In a conventional startup control sequence for a combined cycle plant, as described in Patent Document 1, the output of the gas turbine is maintained constant after the gas turbine is accelerated until steam can be supplied to the steam turbine. In such a conventional startup control sequence, it is necessary to wait until steam can be supplied to the steam turbine, and this waiting time is one of the factors that lengthen the startup time of a combined cycle plant. It is desirable to shorten the startup time of a combined cycle plant from the viewpoint of improving the operational efficiency of the plant, etc.

[0007] At least one embodiment of the present disclosure has been made in consideration of the above-described circumstances, and an object of the present disclosure is to provide a combined cycle plant startup method, a combined cycle plant startup control device, and a combined cycle plant that are capable of shortening the startup time required for cold startup. [Means for solving the problem]

[0008] In order to solve the above problem, a combined cycle plant startup method according to at least one embodiment of the present disclosure includes: A gas turbine; a heat recovery boiler capable of generating steam by utilizing heat contained in exhaust gas discharged from the gas turbine; a steam turbine that can be driven by using the steam; A combined cycle plant start-up method for starting up a combined cycle plant comprising: starting up the gas turbine; controlling an output of the gas turbine to be a first output for a predetermined period after a rotation speed of the gas turbine reaches a reference rotation speed; After the predetermined period has elapsed, controlling the output to a second output which is smaller than the first output; starting a supply of the steam to the steam turbine when a temperature of the steam becomes lower than a preset upper limit temperature; Equipped with.

[0009] In order to solve the above problems, the combined cycle plant startup control device according to at least one embodiment of the present disclosure includes: A gas turbine; a heat recovery boiler capable of generating steam by utilizing heat contained in exhaust gas discharged from the gas turbine; a steam turbine that can be driven by using the steam; A combined cycle plant startup control device for performing startup control of a combined cycle plant, comprising: an output control unit for controlling the gas turbine; a steam turbine control unit for controlling the steam turbine; Equipped with the gas turbine control unit controls an output of the gas turbine to a first output for a predetermined period after a rotation speed of the started gas turbine reaches a reference rotation speed, and controls the output to a second output smaller than the first output after the predetermined period has elapsed; The steam turbine control unit starts supplying the steam to the steam turbine when the temperature of the steam becomes lower than a preset upper limit temperature.

[0010] In order to solve the above problems, a combined cycle plant according to at least one embodiment of the present disclosure includes: The gas turbine; The heat recovery steam generator; The steam turbine; A combined cycle plant startup control device according to at least one embodiment of the present disclosure; Equipped with. Effect of the Invention

[0011] At least one embodiment of the present disclosure has been made in consideration of the above-described circumstances, and can provide a combined cycle plant startup method, a combined cycle plant startup control device, and a combined cycle plant that can shorten the startup time required for cold startup. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of a combined cycle plant according to an embodiment. FIG. [Diagram 2] 2 is a block diagram of a control device for the combined cycle plant in FIG. 1. [Diagram 3] 3 is a flowchart illustrating a startup control method for a combined cycle plant according to an embodiment. [Figure 4] 4 is a timing chart showing the time variations of parameters indicating the operating state of the combined cycle plant corresponding to FIG. 3. [Diagram 5] This is a comparative example to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the configurations described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0014] First, a configuration of a combined cycle plant 1 that is a control target of a combined cycle plant startup control device according to at least one embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of a combined cycle plant 1 according to one embodiment.

[0015] The combined cycle plant 1 includes a gas turbine 10, a heat recovery boiler 20 for generating steam using exhaust gas EG from the gas turbine 10, a steam turbine 30 that can be driven by steam from the heat recovery boiler 20, a condenser 40 for converting the steam from the steam turbine 30 back into water, a feedwater pump 76 for sending the water in the condenser 40 to the heat recovery boiler 20, a generator 45, and a starter motor 49.

[0016] The gas turbine 10 includes a compressor 11 that compresses air A, a combustor 14 that can generate combustion gas by burning fuel F together with the air compressed by the compressor 11, and a turbine 15 that can be driven by the high-temperature, high-pressure combustion gas. The compressor 11 has a compressor rotor 12 that rotates about an axis Ar, a compressor casing 13 that covers the compressor rotor 12, and an inlet guide vane 44 (IGV) whose opening is variable to adjust the intake air flow rate to the compressor 11. The opening D of the inlet guide vane 44 can be adjusted by a control device 100 described later.

[0017] The turbine 15 has a turbine rotor 16 rotatable about an axis Ar, and a turbine casing 17 covering the turbine rotor 16. The compressor rotor 12 and the turbine rotor 16 are connected to each other so as to be rotatable integrally about the same axis Ar, thereby constituting a gas turbine rotor 19. A fuel supply line 65 for supplying fuel F to the combustor 14 is connected to the combustor 14. A fuel valve 66 for adjusting the flow rate of the fuel F supplied to the combustor 14 is provided in the fuel supply line 65. The flow rate of the fuel F to the combustor 14 is transmitted as an index corresponding to the output G of the combined cycle plant 1 to a control device 100 described later as one of parameters indicating the operating state.

[0018] The heat recovery boiler 20 has an economizer 21 capable of heating the water from the condenser 40 with heat contained in the exhaust gas EG, an evaporator 22 capable of heating the water heated by the economizer 21 with the heat of the exhaust gas EG to generate steam, and a superheater 23 capable of further superheating the steam with the heat of the exhaust gas EG. The economizer 21, the evaporator 22, and the superheater 23 all have heat transfer tubes through which water or steam passes and which exchange heat between the water or steam and the exhaust gas EG. The evaporator 22 has a drum 22a in addition to the heat transfer tubes.

[0019] The heat recovery boiler 20 also has an exhaust gas treatment device 57 for treating the exhaust gas EG that exchanges heat with water or steam passing through the economizer 21, the evaporator 22, and the superheater 23. The exhaust gas treatment device 57 is an SCR denitration device including a catalyst for removing nitrogen oxides contained in the exhaust gas EG. The exhaust gas treatment device 57 is disposed in the heat recovery boiler 20 between the economizer 21 and the evaporator 22 so as to be able to exchange heat with water or steam. The exhaust gas treatment device 57 also has an exhaust gas temperature sensor 98 for detecting the temperature of the exhaust gas EG introduced into the exhaust gas treatment device 57 (hereinafter referred to as exhaust gas temperature Tex).

[0020] The steam turbine 30 has a steam turbine rotor 31 rotatable about an axis Ar, a steam turbine casing 34 covering the steam turbine rotor 31, and a shaft seal device 39. The steam turbine rotor 31 has a rotor shaft 32 rotatable about the axis Ar, and a plurality of moving blade rows 33 fixed to the rotor shaft 32. The plurality of moving blade rows 33 are arranged along the axial direction in which the axis Ar extends. A plurality of stator blade rows 36 are fixed to an inner circumferential surface of the steam turbine casing 34. The plurality of stator blade rows 36 are arranged along the direction in which the axial direction extends. Each of the plurality of stator blade rows 36 is disposed upstream of the steam flow with respect to any one of the plurality of moving blade rows 33.

[0021] The shaft seal device 39 is a device for preventing steam from entering the steam turbine casing 34 through a gap between the end of the steam turbine rotor 31 and the steam turbine casing 34 due to external steam. Note that although the steam turbine 30 shown in Fig. 1 is a two-way split exhaust steam turbine that splits the flow of incoming steam into two directions, it may be a steam turbine that does not split the flow of incoming steam.

[0022] The condenser 40 has a heat transfer tube 42 through which a cooling medium such as water flows, and a condenser casing 41 which covers the heat transfer tube 42. Steam from the steam turbine 30 flows into the condenser casing 41 and is cooled by heat exchange with the cooling medium in the heat transfer tube 42 to become water. The condenser casing 41 is provided with an exhaust line 70 for exhausting gas in the condenser casing 41 to the outside and reducing the pressure in the condenser casing 41. The exhaust line 70 is provided with a vacuum pump 71 for sucking gas in the condenser casing 41. The condenser casing 41 is further provided with an outside air line 72 for introducing outside air into the condenser casing 41. The outside air line 72 is provided with a vacuum breaker valve 73.

[0023] The generator 45 has a generator rotor 46 that is rotatable about an axis Ar, and a generator casing 47 that covers the generator rotor 46. The generator 45 is electrically connected to an external system 63 by a connection line 60.

[0024] The gas turbine rotor 19, the steam turbine rotor 31, and the generator rotor 46 are located on the same axis Ar and are mechanically connected to one another. That is, the combined cycle plant 1 is a single-shaft combined cycle plant. The starter motor 49 can rotate these rotors about the axis Ar.

[0025] In addition to the above configuration, the combined cycle plant 1 includes a low-temperature steam generation source 50 capable of generating low-temperature steam independent of the heat recovery steam generator 20. The combined cycle plant 1 further includes a feed water line 75, a main steam line 77, a shutoff valve 78, a control valve 79, a plurality of boiler water discharge lines 88, and a plurality of boiler water discharge valves 89.

[0026] A feedwater line 75 connects the condenser casing 41 and the economizer 21. A feedwater pump 76 is provided in this feedwater line 75. A main steam line 77 connects the superheater 23 and a steam inlet of the steam turbine casing 34. A shutoff valve 78 and a control valve (main steam control valve) 79 are provided in the main steam line 77. A steam turbine inlet temperature sensor 96 is provided upstream of the shutoff valve 78 to detect the temperature of steam supplied to the inlet of the steam turbine 30 by opening the shutoff valve 78 and the control valve 79 (hereinafter referred to as the steam turbine inlet temperature T1T).

[0027] Of the multiple boiler water discharge lines 88, a first end of the first boiler water discharge line 88a is connected to the drum 22a of the evaporator 22. A second end of the first boiler water discharge line 88a is connected to the condenser casing 41. Of the multiple boiler water discharge valves 89, the first boiler water discharge valve 89a is provided on this first boiler water discharge line 88a. Of the multiple boiler water discharge lines 88, a first end of the second boiler water discharge line 88b is connected to the vicinity of the outlet of the heat transfer tube that constitutes the superheater 23. A second end of the second boiler water discharge line 88b is connected to the condenser casing 41. Of the multiple boiler water discharge valves 89, the second boiler water discharge valve 89b is provided on the second boiler water discharge line 88b.

[0028] Next, a control device 100 for controlling the combined cycle plant 1 having the above configuration will be described. In this embodiment, the control device 100 is particularly a start-up control device for starting up the combined cycle plant 1 in a cold state. Fig. 2 is a block diagram of the control device 100 for the combined cycle plant 1 in Fig. 1.

[0029] The control device 100 is composed of, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example, and the CPU reads the program into the RAM or the like and executes information processing and arithmetic processing to realize various functions. The program may be installed in a ROM or other storage medium in advance, may be provided in a state stored in a computer-readable storage medium, or may be distributed via a wired or wireless communication means. The computer-readable storage medium may be a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

[0030] As shown in FIG. 2, the control device 100 includes an operating state acquisition unit 102, a gas turbine control unit 104, an output control unit 106, a counting unit 108, an exhaust gas treatment device control unit 110, a steam supply start condition determination unit 112, a steam turbine control unit 114, and an IGV opening control unit 116.

[0031] The operating state acquisition unit 102 is configured to acquire the operating state of the combined cycle plant 1. The operating state can broadly include parameters related to each element constituting the combined cycle plant 1 described above and used in the control calculation by the control device 100. In this embodiment, the parameters indicating the operating state include at least the exhaust gas temperature Tex detected by the exhaust gas temperature sensor 98, the steam turbine inlet temperature T1T detected by the steam turbine inlet temperature sensor 96, and the rotation speed Rg of the gas turbine 10, the rotation speed Rs of the steam turbine 30, the output G corresponding to the flow rate of the fuel F to the combustor 14, and the opening degree D of the inlet guide vane 44, which can be specified based on a control signal handled by the control device 100.

[0032] The gas turbine control unit 104 is configured to control the gas turbine 10 based on the operating state acquired by the operating state acquisition unit 102. The control parameters related to the gas turbine 10 that are targeted by the gas turbine control unit 104 are not limited, but in this embodiment, at least the rotation speed Rg of the gas turbine 10 is included.

[0033] The output control unit 106 is configured to control the output G of the combined cycle plant 1 based on the operating state of the combined cycle plant 1. As described above, the output G of the combined cycle plant 1 is specified as an index based on the supply flow rate of the fuel F to the combustor 14 provided in the gas turbine 10. Note that, since the output G of the combined cycle plant 1 is a combined value of the gas turbine output and the steam turbine output, when the output control unit 106 controls the output G, at least one of the gas turbine 10 or the steam turbine 30 can be set as a control target. That is, the output control unit 106 may control the output G with the gas turbine 10 as the control target, or may control the output G with the steam turbine 30 as the control target.

[0034] The counting unit 108 is a component for counting the time that has elapsed since a predetermined time. The counting by the counting unit 108 is started, for example, by receiving a signal instructing the start of counting from another component.

[0035] The exhaust gas treatment device control unit 110 is configured to control the exhaust gas treatment device 57 based on the operating state of the combined cycle plant 1. When starting up the combined cycle plant 1 in a cold state, it is necessary that the SCR in-service condition, which is a condition for starting the treatment of the exhaust gas EG by the exhaust gas treatment device 57, is established. As described above, the exhaust gas treatment device 57 includes a catalyst for treating nitrogen oxides contained in the exhaust gas EG from the gas turbine 10, and the exhaust gas treatment function requires that the temperature of the catalyst becomes a predetermined value or higher. The SCR in-service condition includes that the exhaust gas temperature Tex, which is a representative temperature of the exhaust gas treatment device 57, becomes a predetermined threshold value or higher. This threshold value is set as a reference temperature corresponding to the catalyst temperature at which the exhaust gas treatment device 57 can sufficiently treat the nitrogen oxides contained in the exhaust gas EG. When such an SCR in-service condition is established, the exhaust gas treatment device control unit 110 controls the exhaust gas treatment device 57 so that the exhaust gas treatment by the exhaust gas treatment device 57 is started.

[0036] The steam supply start condition determination unit 112 is configured to determine whether a steam supply start condition is satisfied. The steam supply start condition is a condition for starting the supply of steam, which is a working medium, to the steam turbine 30, and includes at least a condition that the steam turbine inlet temperature T1T is equal to or lower than a preset steam temperature.

[0037] The steam turbine control unit 114 is configured to control the steam turbine 30 based on the operating state of the combined cycle plant 1. In this embodiment, when the steam supply start condition is satisfied by the steam supply start condition determination unit 112, control is performed to start steam supply to the steam turbine 30. The steam supply start condition includes at least a condition in which the steam turbine inlet temperature T1T is equal to or lower than a preset upper limit temperature.

[0038] The IGV opening control unit 116 is configured to control the opening D of the inlet guide vane 44 based on the operating conditions of the combined cycle plant 1.

[0039] Next, a description will be given of a startup control method for the combined cycle plant 1 implemented by the control device 100 having the above configuration. Fig. 3 is a flowchart showing a startup control method for the combined cycle plant 1 according to one embodiment, and Fig. 4 is a timing chart showing the time changes of each parameter indicating the operating state of the combined cycle plant 1 corresponding to Fig. 3.

[0040] First, the control device 100 starts up the gas turbine 10, which is in a cold state at time t1 (step S100). In step S100, the gas turbine rotor 19 is rotated together with the steam turbine rotor 31 and the generator rotor 46 by the start-up motor 49, thereby starting up the gas turbine 10.

[0041] Next, the gas turbine control unit 102 controls the gas turbine 10 started in step S100 so as to increase the rotation speed Rg (step S101). Immediately after the gas turbine 10 is started in step S101, the combined cycle plant 1 is in an unloaded state. Thereafter, as shown in Fig. 4, the rotation speed Rg of the gas turbine 10 is controlled to increase from time t1 to time t2 so as to reach a preset reference rotation speed Rref (e.g., a rated rotation speed).

[0042] When the rotation speed Rg of the gas turbine 10 reaches the reference rotation speed Rref at time t2 (step S102: YES), the output control unit 106 controls the gas turbine 10 so that the output G of the combined cycle plant 1 becomes the first output G1 (step S103).

[0043] The first output G1 is set in advance, but is set to be larger than a second output G2 described later. This first output G1 can be set by preparing correlation data in advance that indicates the correlation between the turbine inlet temperature T1T of the gas turbine 10 and the output G, and based on the correlation data, so that the turbine inlet temperature T1T of the gas turbine 10 becomes a predetermined value. This makes it possible to suitably adjust the exhaust gas temperature Tex of the gas turbine 10.

[0044] Next, the counting unit 108 starts counting the elapsed time since the output G was controlled to become the first output G1 in step S103 (i.e., measuring the elapsed time from time t2) (step S104). Furthermore, the exhaust gas treatment device control unit 110 starts exhaust gas treatment by the exhaust gas treatment device 57 at the timing (time t3) when the SCR in-service condition is established (step S105). The SCR in-service condition includes, among the operating conditions acquired by the operating condition acquisition unit 102, the exhaust gas temperature Tex detected by the exhaust gas temperature sensor 98 becoming equal to or higher than a predetermined threshold value. This threshold value is set as a reference temperature corresponding to a catalyst temperature at which the exhaust gas treatment device 57 can sufficiently treat the nitrogen oxides contained in the exhaust gas EG.

[0045] When the output G is controlled to the first output G1 in step S103, the temperature of the exhaust gas EG, which was in a cold state, gradually increases. In step S105, the temperature of the exhaust gas EG, which gradually increases in this manner, becomes sufficiently high, and the exhaust gas treatment device 57 is started at the timing (time t3) at which the SCR in-service condition is established.

[0046] Next, at time t4, when the elapsed time since counting began in step S104 reaches a predetermined period Tp (step S106: YES), the output control unit 106 controls the output G to become the second output G2 (step S107). The second output G2 is smaller than the first output G1, and may be, for example, an output value corresponding to a conventional initial input load. The predetermined period Tp is preset in step S105 so as to be longer than the period from the start of counting in step S104 until the SCR in-service condition is satisfied.

[0047] Subsequently, the steam supply start condition determination unit 112 determines whether the steam supply start condition is satisfied for the steam turbine 30 (step S108). The steam supply start condition is a condition for starting the supply of steam to the steam turbine 30. In the present embodiment, as an example of the steam supply start condition, it includes that the steam turbine inlet temperature T1T is lower than a preset upper limit temperature Tr.

[0048] When the steam supply start condition is satisfied (step S108), the steam turbine control unit 114 starts the supply of steam to the steam turbine 30 (step S109). In FIG. 4, when the steam supply start condition (T1T < Tr) is satisfied at time t5, it is shown that the rotational speed Rs of the steam turbine 30 increases with the start of the steam supply to the steam turbine 30.

[0049] Here, FIG. 5 is a comparative example of FIG. 4. In this comparative example, the gas turbine 10 is controlled so that the output G becomes the second output G2 (< the first output G1) from the time t2 when the rotational speed Rg of the gas turbine 10 reaches the reference rotational speed Rref (that is, it is different in that there is no period during which the output G becomes the first output G1 compared to the above-described embodiment). Therefore, since the output G is controlled from the first output G1 to the second output G2, in the comparative example shown in FIG. 5, the timing (time t3) at which the exhaust gas treatment by the exhaust gas treatment device 57 starts when the SCR in-service condition is satisfied, and the timing (time t5) at which the steam supply start condition is satisfied, are later than those in the embodiment shown in FIG. 4 described above. That is, in the present embodiment shown in FIG. 4, by temporarily increasing the output G1 to the first output G1 during the period Tp, compared to the comparative example shown in FIG. 5, the time required for the startup sequence at cold startup can be effectively shortened. In particular, by shortening the period until the SCR in-service condition is satisfied, the exhaust gas treatment by the exhaust gas treatment device 57 at cold startup can be started earlier, and the amount of nitrogen oxides discharged to the outside can be effectively reduced.

[0050] 4, the IGV opening control unit may control the IGV from the minimum opening D0 to a first opening D1, which is a partially open state, during a predetermined period T in which the output G is controlled to the first output G1. In this case, the IGV may be controlled to a second opening D2 larger than the first opening D1 during a period in which the output G is controlled to the second output G2 after the predetermined period T has elapsed. In this way, by controlling the opening D of the inlet guide vane 44 to be relatively small during the predetermined period T in which the output G is controlled to the first output G1, the temperature of the exhaust gas EG during the predetermined period T can be more effectively increased and the time required for the exhaust gas treatment device 57 described above to start treating the exhaust gas can be more effectively shortened.

[0051] As described above, according to the above embodiment, after the rotation speed Rg of the gas turbine 10 reaches the reference rotation speed Rref, the output G is controlled to be the first output G1 for the predetermined period T. The first output G1 is set to be larger than the second output G2, thereby accelerating the rise in temperature of the exhaust gas EG of the gas turbine in the predetermined period T. As a result, the rise in temperature of the steam generated by the exhaust heat recovery boiler is also accelerated, and the timing for starting the supply of steam to the steam turbine 30 can be advanced. This allows the start-up time of the combined cycle plant 1 to be effectively shortened.

[0052] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

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

[0054] (1) A method for starting up a combined cycle plant according to one embodiment includes the steps of: A gas turbine; a heat recovery boiler capable of generating steam by utilizing heat contained in exhaust gas discharged from the gas turbine; a steam turbine that can be driven by using the steam; A combined cycle plant start-up method for starting up a combined cycle plant comprising: starting up the gas turbine; controlling an output of the gas turbine to be a first output for a predetermined period after a rotation speed of the gas turbine reaches a reference rotation speed; After the predetermined period has elapsed, controlling the output to a second output which is smaller than the first output; starting a supply of the steam to the steam turbine when a temperature of the steam becomes lower than a preset upper limit temperature; Equipped with.

[0055] According to the above aspect (1), after the rotation speed of the gas turbine reaches the reference rotation speed, the rotation speed of the gas turbine is controlled to be the first output for a predetermined period. The first output is set to be larger than the second output, thereby promoting the rise in temperature of the exhaust gas from the gas turbine for the predetermined period. As a result, the rise in temperature of the steam generated by the heat recovery boiler is also promoted, and the timing for starting the supply of steam to the steam turbine can be advanced. This effectively shortens the start-up time of the combined cycle plant.

[0056] (2) In another embodiment, in the above embodiment (1), The second output is set so that the temperature of the steam at the start of ventilation of the steam turbine is lower than the upper limit temperature.

[0057] According to the above aspect (2), it is possible to effectively reduce the time required from the start of startup until the condition for starting the supply of steam to the steam turbine is satisfied.

[0058] (3) In another embodiment, in the above embodiment (1) or (2), The combined cycle plant further includes a denitration device for performing a denitration treatment on the exhaust gas, The combined cycle plant startup method includes: The method further includes the step of starting up the denitration device while the output is controlled to be the first output.

[0059] According to the above aspect (3), by controlling the output of the gas turbine to be the first output set to be greater than the second output during a predetermined period, it is possible to promote the temperature rise of the denitration device disposed downstream of the exhaust gas flow path of the gas turbine. Since the start-up condition of the denitration device is to reach a temperature at which catalytic action can be obtained, the denitration device can be started up quickly. As a result, the amount of nitrogen oxide (NOx) emissions from the plant can be effectively reduced.

[0060] (4) In another embodiment, in the above embodiment (3), The predetermined period is set to continue until a preset time has elapsed from the start of the denitration device.

[0061] According to the above aspect (4), the predetermined period during which the output of the gas turbine is controlled to the first output continues until a preset time has elapsed from the start-up of the denitration device, whereby the output of the gas turbine can be reduced from the first output to the second output after the start-up of the denitration device has been reliably performed.

[0062] (5) In another embodiment, in any one of the above (1) to (4), The gas turbine has an inlet guide vane capable of adjusting an inlet flow rate by changing an inlet opening degree of a compressor, controlling an opening degree of the inlet guide vane to a first opening degree during the predetermined period; After the predetermined period has elapsed, the opening degree is controlled to be larger than the first opening degree.

[0063] According to the above aspect (5), the opening degree of the inlet guide vane is controlled to be relatively small during a predetermined period in which the output of the gas turbine is controlled to the first output, thereby making it possible to more effectively increase the exhaust gas temperature of the gas turbine during the predetermined period.

[0064] (6) In another embodiment, in any one of the above (1) to (5), The first output is set based on correlation data indicating a correlation between a turbine inlet temperature of the gas turbine and the output, so that the turbine inlet temperature of the gas turbine becomes a predetermined value.

[0065] According to the above aspect (6), a correlation between the turbine inlet temperature and the output of the gas turbine is prepared in advance as correlation data. The first output, which is a control target value of the output of the gas turbine for a predetermined period, is set based on such correlation data so that the turbine inlet temperature becomes a predetermined value. This makes it possible to suitably adjust the exhaust gas temperature of the gas turbine.

[0066] (7) A combined cycle plant startup control device according to one embodiment includes: A gas turbine; a heat recovery boiler capable of generating steam by utilizing heat contained in exhaust gas discharged from the gas turbine; a steam turbine that can be driven by using the steam; A combined cycle plant startup control device for performing startup control of a combined cycle plant, comprising: an output control unit for controlling the gas turbine; a steam turbine control unit for controlling the steam turbine; Equipped with the gas turbine control unit controls an output of the gas turbine to a first output for a predetermined period after a rotation speed of the started gas turbine reaches a reference rotation speed, and controls the output to a second output smaller than the first output after the predetermined period has elapsed; The steam turbine control unit starts supplying the steam to the steam turbine when the temperature of the steam becomes lower than a preset upper limit temperature.

[0067] According to the above aspect (7), after the rotation speed of the gas turbine reaches the reference rotation speed, the rotation speed of the gas turbine is controlled to be the first output for a predetermined period. The first output is set to be larger than the second output, thereby promoting the rise in temperature of the exhaust gas from the gas turbine for the predetermined period. As a result, the rise in temperature of the steam generated by the exhaust heat recovery boiler is also promoted, and the timing for starting the supply of steam to the steam turbine can be advanced. This effectively shortens the start-up time of the combined cycle plant.

[0068] (8) A combined cycle plant according to one embodiment includes: The gas turbine; The heat recovery steam generator; The steam turbine; A combined cycle plant startup control device according to one embodiment, Equipped with.

[0069] According to the above aspect (8), the startup time of the combined cycle plant can be effectively shortened by the combined cycle plant startup control device. [Explanation of symbols]

[0070] 1. Combined cycle plant 10. Gas Turbine 11 Compressor 13 Compressor casing 14 Combustor 15 Turbine 16 Turbine rotor 17 Turbine casing 19 Gas turbine rotor 20. Waste heat recovery boiler 21 Economizer 22 Evaporator 22a Drum 23 Superheater 30 Steam Turbine 31 Steam turbine rotor 32 Rotor shaft 33 Moving blade row 34 Steam turbine casing 36 Stator blade row 39 Shaft sealing device 40 Condenser 41 Condenser casing 42 Heat transfer tube 44 Inlet guide vane 45 Generator 46 Generator rotor 47 Generator casing 49 Starting motor 50 Low-temperature steam source 51 Auxiliary boiler 57 Exhaust Gas Treatment Device 59 Pressure Control Valve 65 Fuel supply line 60 Connection Line 63 External system 66 Fuel valve 70 Exhaust line 71 Vacuum Pump 72 Outside air line 73 Vacuum breaker valve 75 Water Supply Line 76 Water Pump 77 Main Steam Line 78 Shut-off valve 79 Regulating valve 88 Boiler water discharge line 88a First boiler water discharge line 88b Second boiler water discharge line 89 Boiler water distribution valve 89a First boiler water distribution valve 89b Second boiler water distribution valve 96 Steam turbine inlet temperature sensor 98 Exhaust Gas Temperature Sensor 100 Control device 102 Operation status acquisition unit 104 Gas Turbine Control Unit 106 Output control section 108 Counting section 110 Exhaust gas treatment device control section 112 Steam supply start condition determination unit 114 Steam turbine control section 116 IGV opening control unit

Claims

1. A gas turbine; a heat recovery boiler capable of generating steam by utilizing heat contained in exhaust gas discharged from the gas turbine; a steam turbine that can be driven by using the steam; A combined cycle plant start-up method for starting up a combined cycle plant comprising: starting up the gas turbine; controlling an output of the gas turbine to be a first output for a predetermined period after a rotation speed of the gas turbine reaches a reference rotation speed; After the predetermined period of time has elapsed, controlling the output to a second output which is smaller than the first output; starting a supply of the steam to the steam turbine when a temperature of the steam becomes lower than a preset upper limit temperature; A method for starting up a combined cycle plant.

2. 2 . The method for starting up a combined cycle plant according to claim 1 , wherein the second output is set so that a temperature of the steam at a start of ventilation of the steam turbine is lower than the upper limit temperature.

3. The combined cycle plant further includes a denitration device for performing a denitration treatment on the exhaust gas, The combined cycle plant startup method includes:

3. The combined cycle plant start-up method according to claim 1, further comprising the step of starting up the denitrification device while the output is controlled to be the first output.

4. 4. The combined cycle plant start-up method according to claim 3, wherein the predetermined period is set to continue until a preset time has elapsed from the start-up of the denitration device.

5. The gas turbine has an inlet guide vane capable of adjusting an inlet flow rate by changing an inlet opening degree of a compressor, controlling an opening degree of the inlet guide vane to a first opening degree during the predetermined period; 3. The combined cycle plant startup method according to claim 1, further comprising the step of: controlling the opening degree to be greater than the first opening degree after the predetermined period has elapsed.

6. 3. The combined cycle plant startup method according to claim 1, wherein the first output is set based on correlation data indicating a correlation between a turbine inlet temperature of the gas turbine and the output, so that the turbine inlet temperature of the gas turbine becomes a predetermined value.

7. A gas turbine; a heat recovery boiler capable of generating steam by utilizing heat contained in exhaust gas discharged from the gas turbine; a steam turbine that can be driven by using the steam; A combined cycle plant startup control device for performing startup control of a combined cycle plant, comprising: an output control unit for controlling the gas turbine; a steam turbine control unit for controlling the steam turbine; Equipped with the gas turbine control unit controls an output of the gas turbine to a first output for a predetermined period after a rotation speed of the started gas turbine reaches a reference rotation speed, and controls the output to a second output smaller than the first output after the predetermined period has elapsed; The steam turbine control unit starts supplying the steam to the steam turbine when the temperature of the steam becomes lower than a preset upper limit temperature.

8. The gas turbine; The heat recovery steam generator; The steam turbine; The combined cycle plant startup control device according to claim 7 ; A combined cycle plant comprising:

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