Control device for steam turbine facility, steam turbine system, control method for steam turbine facility, and control program for steam turbine facility

Abstract

To provide a control device or the like for a steam turbine facility, which can suppress fluctuations in the water level of an intermediate-pressure drum during transition of an operation state, for example, at the time of startup.SOLUTION: A control device for a steam turbine facility is for controlling the steam turbine facility including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine. The steam turbine facility includes an intermediate-pressure steam line for leading steam from an intermediate-pressure drum to the intermediate-pressure turbine, and a pressure regulation valve provided in a first portion of the intermediate-pressure steam line, which is upstream of a confluence point where steam from a high-pressure drum for generating steam to be supplied to the high-pressure turbine joins. The control device is configured to maintain the degree of opening of the pressure regulation valve within a first range during load operation at a predetermined load of the steam turbine facility, and to maintain the degree of opening of the pressure regulation valve within a second range, in which the degree of opening is smaller than that in the first range, during transition of the operation state of the steam turbine facility between no-load operation and the load operation.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a control device for steam turbine equipment, a steam turbine system, a control method for steam turbine equipment, and a control program for steam turbine equipment.

Background Art

[0002] In a combined cycle power plant or the like, a steam turbine including a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine with different inlet steam pressures is employed.

[0003] Patent Document 1 discloses a combined power generation plant including a gas turbine and a steam turbine including a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine. Steam generated in the steam drums (high-pressure drum, medium-pressure drum, and low-pressure drum) of the steam generation facility is supplied to the high-pressure turbine, the medium-pressure turbine, and the low-pressure turbine, respectively.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in a steam turbine facility, in the steam line for guiding steam from the steam drum to the turbine, there is a portion where pressure fluctuations become large due to opening and closing of various valves during a transition in the operating state such as at startup of the steam turbine facility. When the pressure of the steam drum fluctuates under the influence of this pressure fluctuation, the water level of the steam drum also fluctuates. However, if the water level of the steam drum fluctuates rapidly, the steam turbine facility may be stopped urgently due to this. Further, in a steam turbine facility including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, in terms of heat balance, the volume of the intermediate-pressure drum is relatively small compared to that of the high-pressure drum and the like. For this reason, the drum water level in the intermediate-pressure drum is particularly likely to fluctuate relatively easily.

[0006] In view of the above circumstances, at least one embodiment of the present invention aims to provide a control device for a steam turbine facility, a steam turbine system, a control method for a steam turbine facility, and a control program for a steam turbine facility that can suppress fluctuations in the water level of an intermediate-pressure drum during a transition in the operating state such as at startup.

Means for Solving the Problem

[0007] The control device for a steam turbine facility according to at least one embodiment of the present invention is a control device for controlling a steam turbine facility including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, wherein the steam turbine facility includes an intermediate-pressure steam line for guiding steam from the intermediate-pressure drum to the intermediate-pressure turbine, and a pressure regulating valve provided in a first portion on the upstream side of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges in the intermediate-pressure steam line, and is configured to maintain the opening degree of the pressure regulating valve within a first range during load operation at a predetermined load of the steam turbine facility, and maintain the opening degree of the pressure regulating valve within a second range having a smaller opening degree than the first range during a transition in the operating state between no-load operation and load operation of the steam turbine facility. is configured as such.

[0008] Also, the steam turbine system according to at least one embodiment of the present invention includes a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, an intermediate-pressure steam line for guiding steam from an intermediate-pressure drum to the intermediate-pressure turbine, a pressure regulating valve provided in a first portion upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges in the intermediate-pressure steam line, steam turbine equipment including, the above-described control device configured to control the steam turbine equipment, and includes.

[0009] Also, a control method for steam turbine equipment according to at least one embodiment of the present invention is a control method for controlling steam turbine equipment including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, wherein the steam turbine equipment includes an intermediate-pressure steam line for guiding steam from an intermediate-pressure drum to the intermediate-pressure turbine, a pressure regulating valve provided in a first portion upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges in the intermediate-pressure steam line, and includes, a step of maintaining the opening degree of the pressure regulating valve within a first range during load operation at a predetermined load of the steam turbine equipment, a step of maintaining the opening degree of the pressure regulating valve within a second range having a smaller opening degree than the first range when shifting the operating state between no-load operation and load operation of the steam turbine equipment, and includes.

[0010] Also, a control program for steam turbine equipment according to at least one embodiment of the present invention is a control program for controlling steam turbine equipment including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, wherein the steam turbine equipment An intermediate-pressure steam line for guiding steam from the intermediate-pressure drum to the intermediate-pressure turbine, a pressure regulating valve provided in a first portion of the intermediate-pressure steam line upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges, and a computer, a procedure for maintaining the opening degree of the pressure regulating valve within a first range during a load operation at a predetermined load of the steam turbine facility, a procedure for maintaining the opening degree of the pressure regulating valve within a second range having a smaller opening degree than the first range when shifting the operating state between an unloaded operation and a loaded operation of the steam turbine facility, are configured to be executed.

Advantages of the Invention

[0011] According to at least one embodiment of the present invention, there are provided a control device for a steam turbine facility, a steam turbine system, a control method for a steam turbine facility, and a control program for a steam turbine facility that can suppress fluctuations in the water level of an intermediate-pressure drum during a transition in the operating state such as at startup.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0013] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0014] (Configuration of Steam Turbine System) FIG. 1 is a schematic diagram of a gas turbine combined cycle power plant (hereinafter abbreviated as GTCC power plant) including a steam turbine facility (steam turbine system) according to an embodiment. FIG. 2 is a schematic diagram of a steam turbine system including a steam turbine steam facility according to an embodiment.

[0015] The GTCC power plant 1 shown in FIG. 1 includes a steam turbine facility 100 (see FIG. 2) including a steam turbine 10, a gas turbine 40, a generator 4, and an exhaust heat recovery boiler 50.

[0016] Note that the steam turbine facility according to some embodiments is not limited to the steam turbine facility for a combined cycle power plant described below. For example, it may be a steam turbine facility for a steam power plant that drives a steam turbine with steam generated by a boiler that burns fuels such as coal, oil, liquefied natural gas, and heavy oil.

[0017] As shown in FIGS. 1 and 2, the steam turbine 10 includes a plurality of turbines having different inlet steam pressures. The plurality of turbines includes a high-pressure turbine 12, an intermediate-pressure turbine 14, and a low-pressure turbine 16. The inlet pressure of the intermediate-pressure turbine 14 is lower than the inlet pressure of the high-pressure turbine 12. The inlet pressure of the low-pressure turbine 16 is lower than the inlet pressure of the intermediate-pressure turbine 14.

[0018] At the inlet of each turbine, steam valves (high-pressure steam valve 22, intermediate-pressure steam valve 24, and low-pressure steam valve 26) are provided, and each turbine is driven by the steam supplied through each steam valve (22, 24, 26). The plurality of turbines constituting the steam turbine 10 are connected to the generator 4 and are configured to drive the generator 4.

[0019] The steam for driving the steam turbine 10 is generated using the exhaust gas of the gas turbine 40 as a heat source.

[0020] As shown in FIG. 1, the gas turbine 40 includes a compressor 42 for generating compressed air, a combustor 44 for burning fuel using the compressed air generated by the compressor 42 to generate combustion gas, and a turbine 46 driven by the combustion gas from the combustor 44. The rotor of the turbine 46 is connected to the input shaft of the generator 4, and in the generator 4, the mechanical energy input from the turbine 46 is converted into electric power. Further, the rotating shaft of the compressor 42 is connected to the rotor of the turbine 46, and the compressor 42 is driven by the turbine 46.

[0021] In the gas turbine 40, the combustion gas after passing through the turbine 46 is led to the exhaust heat recovery boiler 50 as exhaust gas 48.

[0022] As shown in FIGS. 1 and 2, the waste heat recovery boiler 50 includes a plurality of steam drums (52, 54, 56) provided corresponding to a plurality of types of turbines constituting the steam turbine 10, evaporators (53, 55, 57) connected to each steam drum (52, 54, 56), and superheaters (62, 64, 66) for superheating the steam from each steam drum (52, 54, 56). In the embodiment shown in FIG. 1, a plurality of steam drums including a high-pressure drum 52, a medium-pressure drum 54, and a low-pressure drum 56 are provided corresponding to the high-pressure turbine 12, the medium-pressure turbine 14, and the low-pressure turbine 16 constituting the steam turbine 10, respectively, and a plurality of evaporators (53, 55, 57) and a plurality of superheaters (62, 64, 66) are provided corresponding to each steam drum. Further, the waste heat recovery boiler 50 includes a reheater 65 for reheating the steam discharged from the high-pressure turbine 12.

[0023] Further, the waste heat recovery boiler 50 having the above-described configuration and the steam turbine 10 are connected by a plurality of steam lines. Specifically, high-pressure steam lines 72, medium-pressure steam lines 74, and low-pressure steam lines 76 are provided from the high-pressure drum 52, the medium-pressure drum 54, and the low-pressure drum 56 of the waste heat recovery boiler 50 toward the high-pressure turbine 12, the medium-pressure turbine 14, and the low-pressure turbine 16, respectively. The above-described steam valves (high-pressure steam valve 22, medium-pressure steam valve 24, and low-pressure steam valve 26) are provided at the inlets of the respective turbines in the high-pressure steam line 72, the medium-pressure steam line 74, and the low-pressure steam line 76.

[0024] Further, a high-pressure discharge line 73 is provided for guiding the exhaust from the high-pressure turbine 12 to the reheater 65. The high-pressure discharge line 73 has an upstream end connected to the outlet of the high-pressure turbine 12 and a downstream end connected to a portion between the superheater 64 and the reheater 65 in the medium-pressure steam line 74.

[0025] Furthermore, a medium-pressure discharge line 75 is provided for guiding the exhaust from the medium-pressure turbine 14 to the low-pressure turbine 16. The medium-pressure discharge line 75 has an upstream end connected to the outlet of the medium-pressure turbine 14 and a downstream end connected to a downstream side of the superheater 66 and a downstream side of the low-pressure steam valve 26 in the low-pressure steam line 76.

[0026] The superheaters (62, 64, 66) of the exhaust heat recovery boiler 50 described above are respectively arranged on the steam lines (72, 74, 76) leading to the inlets of the respective turbines (12, 14, 16). Further, the reheater 65 of the exhaust heat recovery boiler 50 is provided on the downstream side of the superheater 64 in the medium-pressure steam line 74.

[0027] Also, in the example shown in FIGS. 1 and 2, a feed water line 78 for supplying water from the condenser 18 connected to the low-pressure turbine 16 to each steam drum (52, 54, 56) is connected to the exhaust heat recovery boiler 50. The steam after passing through the low-pressure turbine 16 is condensed in the condenser 18 and returned to each steam drum (52, 54, 56) via the feed water line 78. In the feed water line 78, feed water valves (102, 104, 106) for adjusting the amount of feed water to each turbine are provided on the inlet side of each steam drum (52, 54, 56).

[0028] In the GTCC plant 1 configured as described above, the exhaust gas of the gas turbine 40 is introduced into the exhaust heat recovery boiler 50, and steam is generated in the evaporators (53, 55, 57) connected to the respective steam drums (52, 54, 56) by heat exchange with the exhaust gas and stored in the respective steam drums (52, 54, 56). Further, the steam from each steam drum (52, 54, 56) is heated by the superheaters (62, 64, 66) and the reheater 65 and supplied to the plurality of turbines (12, 14, 16) constituting the steam turbine 10. The steam after passing through the high-pressure turbine 12 is led to the medium-pressure steam line 74 via the high-pressure discharge line 73, merges with the steam from the superheater 64, and is led to the medium-pressure turbine 14 via the reheater 65. The steam after passing through the medium-pressure turbine 14 is led to the low-pressure steam line 76 via the medium-pressure discharge line 75, merges with the steam from the superheater 66, and is led to the low-pressure turbine 16. The steam after passing through the low-pressure turbine 16 is condensed in the condenser 18 and returned to each steam drum (52, 54, 56) of the exhaust heat recovery boiler 50 via the feed water line 78 as described above.

[0029] In addition, in the case of the configuration where the steam turbine 10 and the gas turbine 40 drive the common generator 4 as in the above-described example, the shaft of the steam turbine 10 and the shafts of the gas turbine 40 and the generator 4 may be connected via a clutch.

[0030] As shown in FIG. 2, the steam turbine facility 100 includes a high-pressure bypass line 82 that branches from the high-pressure steam line 72 and is connected to the high-pressure discharge line 73 without passing through the high-pressure turbine 12. A high-pressure bypass valve 83 for adjusting the flow rate of the steam in the high-pressure bypass line 82 is provided in the high-pressure bypass line 82.

[0031] Further, the steam turbine facility 100 includes a medium-pressure bypass line 84 that branches from a portion (second portion 74b) of the medium-pressure steam line 74 downstream of the confluence point A where the steam from the high-pressure drum 52 merges and is connected to the condenser 18 without passing through the medium-pressure turbine 14. A medium-pressure bypass valve 85 for adjusting the flow rate of the steam in the medium-pressure bypass line 84 is provided in the medium-pressure bypass line 84.

[0032] Also, the steam turbine facility 100 includes a low-pressure bypass line 86 that branches from the low-pressure steam line 76 and is connected to the condenser 18 without passing through the low-pressure turbine 16. A low-pressure bypass valve 87 for adjusting the flow rate of the steam in the low-pressure bypass line 86 is provided in the low-pressure bypass line 86.

[0033] The medium-pressure steam line 74 includes a first portion 74a upstream of the confluence point A where the steam from the high-pressure drum 52 merges and a second portion 74b downstream of the confluence point A. That is, the first portion 74a is the portion of the medium-pressure steam line 74 between the medium-pressure drum 54 and the confluence point A. The second portion 74b is the portion of the medium-pressure steam line 74 between the confluence point A and the medium-pressure turbine 14. In the medium-pressure steam line 74, at the confluence point A, the steam from the high-pressure discharge line 73 and the steam from the high-pressure bypass line 82 merge.

[0034] A pressure regulating valve 94 for adjusting the pressure in the first portion 74a is provided in the first portion 74a of the medium-pressure steam line 74. A check valve 92 may be provided at a position between the medium-pressure drum 54 and the pressure regulating valve 94 in the first portion 74a of the medium-pressure steam line 74.

[0035] As shown in FIG. 2, the steam turbine facility 100 may include a ventilation line 90 that branches from the high-pressure discharge line 73 and is connected to the condenser 18 without passing through the medium-pressure turbine 14 and the low-pressure turbine 16. A ventilator valve 91 for adjusting the steam flow rate in the ventilation line 90 may be provided in the ventilation line 90.

[0036] Also, as shown in FIG. 2, a check valve 96 may be provided in the high-pressure discharge line 73 at a position between the branch point where the ventilation line 90 branches from the high-pressure discharge line 73 and the confluence point to the medium-pressure steam line 74.

[0037] The steam turbine system 110 according to some embodiments includes the above-described steam turbine facility 100 and a control device 112 for controlling the steam turbine facility 100.

[0038] The control device 112 is configured to maintain the opening degree of the pressure regulating valve 94 provided in the first portion 74a of the medium-pressure steam line 74 within a first range during the load operation at the rated load of the steam turbine facility 100, and to maintain the opening degree of the pressure regulating valve 94 within a second range having a smaller opening degree than the first range when shifting the operating state between the no-load operation and the load operation of the steam turbine facility 100.

[0039] The control device 112 includes a computer having a processor (such as a CPU), a main storage device (memory device; such as a RAM), an auxiliary storage device, and an interface, etc. The control device 112 may be configured to receive, via the interface, a signal indicating the operating state of the steam turbine facility 100 from a higher-level control device or the like. The processor may be configured to process the signal received in this way. Further, the processor is configured to process a program developed in the main storage device. Thereby, the functions of the control device 112 are realized.

[0040] The processing content in the control device 112 is implemented as a program executed by the processor. The program may be stored, for example, in the auxiliary storage device. When the program is executed, these programs are developed in the main storage device. The processor reads the program from the main storage device and executes the instructions included in the program.

[0041] The time of load operation at the rated load of the steam turbine facility 100 means a state (steady operation state) in which the steam turbine facility 100 is operated at a substantially constant load, such as during rated operation. The rated load may be the rated load (100% load) or a partial load (a load greater than 0% and less than 100%).

[0042] The time of no-load operation of the steam turbine facility 100 means a state where the steam turbine facility 100 is at no load, and includes, for example, the start-up of the steam turbine facility 100 or when the load is cut off in the steam turbine facility 100 during load operation.

[0043] The transition time of the operating state between the no-load operation and the load operation of the steam turbine facility 100 means at least a part of the period during the transition from the no-load operation to the load operation of the steam turbine facility 100, or at least a part of the period during the transition from the load operation to the no-load operation of the steam turbine facility 100.

[0044] The transition from the no-load operation to the load operation of the steam turbine facility 100 may be, for example, at the time of startup of the steam turbine facility 100, or may also be the period from when the load is interrupted during the load operation of the steam turbine facility 100 until the load is reconnected to the steam turbine facility 100 and the operation transitions to the load operation at the specified load.

[0045] The transition from the load operation to the no-load operation of the steam turbine facility 100 may be, for example, at the time of shutdown of the steam turbine facility 100.

[0046] When the operating state of the steam turbine facility 100 transitions (for example, at the time of startup of the steam turbine facility 100, etc.) between the no-load operation and the load operation (steady operation) at the specified load of the steam turbine facility 100, due to changes in the steam pressure and the opening and closing of various valves (for example, the intermediate pressure bypass valve 85 or the ventilator valve 91, etc.), the pressure fluctuation at the confluence point A where the steam from the high-pressure drum 52 in the intermediate pressure steam line 74 converges is relatively large.

[0047] Here, when the pressure of the intermediate pressure drum 54 fluctuates under the influence of the pressure fluctuation at the confluence point A, the water level of the intermediate pressure drum 54 also fluctuates. However, if the water level of the intermediate pressure drum 54 fluctuates rapidly, the steam turbine facility 100 may be emergently stopped due to this. In the steam turbine facility 100 including the high-pressure turbine 12, the intermediate pressure turbine 14, and the low-pressure turbine 16, due to the heat balance, the volume of the intermediate pressure drum 54 is relatively small compared to the high-pressure drum 52, etc. Therefore, the drum water level in the intermediate pressure drum 54 is particularly likely to fluctuate.

[0048] In this regard, according to the above-described embodiment, a pressure regulating valve 94 is provided in the first portion 74a of the medium-pressure steam line 74 upstream of the above-described confluence point A, and the opening degree of the pressure regulating valve 94 is maintained within a relatively small second range during a period when the pressure fluctuation at the confluence point A is relatively large (i.e., when the operating state of the steam turbine facility 100 transitions). Therefore, during this period, the pressure in the medium-pressure drum 54 is less likely to be affected by the pressure fluctuation at the confluence point A, so that the fluctuation of the water level in the medium-pressure drum 54 can be suppressed. As a result, for example, an emergency stop caused by a sudden fluctuation in the water level of the medium-pressure drum 54 can be suppressed, and the steam turbine facility 100 can be operated more stably.

[0049] The second range of the opening degree of the above-described pressure regulating valve 94 may be an opening degree range such that the pressure at a portion upstream of the pressure regulating valve 94 in the first portion 74a of the medium-pressure steam line 74 (i.e., the portion between the medium-pressure drum 54 and the pressure regulating valve 94) is greater than the pressure at the confluence point A of the medium-pressure steam line 74.

[0050] By maintaining the opening degree of the pressure regulating valve 94 within the above-described range during a period when the pressure fluctuation at the confluence point A is relatively large (when the operating state of the steam turbine facility 100 transitions), the pressure in the medium-pressure drum 54 is less likely to be affected by the pressure fluctuation at the confluence point A during this period, so that the fluctuation of the water level in the medium-pressure drum 54 can be effectively suppressed.

[0051] In some embodiments, during the load operation of the steam turbine facility 100, the opening degree of the pressure regulating valve 94 may be maintained at a first opening degree B1 (fixed opening degree) within the first range.

[0052] In the above-described embodiment, since the opening degree of the pressure regulating valve 94 is maintained at the first opening degree (fixed opening degree) during the load operation (steady operation) at the rated load of the steam turbine facility 100, while making the opening degree control of the pressure regulating valve 94 simpler, the fluctuation of the water level in the medium-pressure drum 54 during the transition of the operating state of the steam turbine facility 100 can be effectively suppressed.

[0053] In some embodiments, when shifting the operating state between the no-load operation and the load operation of the steam turbine facility 100, the opening degree of the pressure regulating valve 94 may be maintained at a second opening degree B2 (fixed opening degree) within a second range.

[0054] In the above-described embodiment, when shifting the operating state of the steam turbine facility 100, the opening degree of the pressure regulating valve 94 is maintained at the second opening degree (fixed opening degree). Therefore, while making the opening degree control of the pressure regulating valve 94 simpler, it is possible to effectively suppress fluctuations in the water level of the intermediate pressure drum 54 when shifting the operating state of the steam turbine facility 100.

[0055] (Control of Steam Turbine Facility) Hereinafter, the control flow of the steam turbine facility 100 according to some embodiments will be described. In the following, an example of controlling the steam turbine facility 100 using the above-described control device 112 will be described, but part or all of the procedures described below may be performed manually.

[0056] FIG. 3 is a chart showing an example of the time change of the operating state of the GTCC plant 1 including the above-described steam turbine facility 100 (steam turbine system 110). In the chart of FIG. 3, the horizontal axis represents time, and the vertical axis represents the loads of the gas turbine 40 and the steam turbine 10, the rotational speeds of the gas turbine 40 and the steam turbine 10, the opening degree of the pressure regulating valve 94, the opening degree of the ventilator valve 91, the opening degree of the intermediate pressure bypass valve 85, the opening degree of the high pressure bypass valve 83, the pressure at the confluence point A of the intermediate pressure steam line 74, and the pressure of the intermediate pressure drum 54, respectively.

[0057] In the chart of FIG. 3, before time t1, the rotation of the gas turbine 40 is started, and the rotational speed of the gas turbine 40 begins to increase. At time t1, the gas turbine 40 is ignited, and the rotational speed of the gas turbine 40 further increases. Also, the exhaust gas from the gas turbine 40 is introduced into the waste heat recovery boiler 50, and the pressure of the intermediate pressure drum 54 begins to rise. Note that the pressures of the high pressure drum 52 and the low pressure drum 56 also begin to rise in the same manner.

[0058] In the steam turbine 10, when the pressure and temperature of the steam satisfy the steam admission conditions to the turbine, the steam admission to the turbine is started, and the rotational speed of the steam turbine 10 begins to increase.

[0059] After time t1, the opening degrees of the respective bypass valves (such as the high-pressure bypass valve 83 and the intermediate-pressure bypass valve 85) are controlled based on the pressures of the high-pressure steam line 72 and the second portion 74b of the intermediate-pressure steam line 74 so that the pressures are within a predetermined range.

[0060] At time t1, the ventilator valve 91 is fully open. The ventilator valve 91 is closed before time t2 when the flow rate control of the steam by each steam valve (such as the high-pressure steam valve 22 and the intermediate-pressure steam valve 24) is started. Thereby, a pressure fluctuation occurs at the junction point A of the intermediate-pressure steam line 74.

[0061] At time t1, the opening degree of the pressure regulating valve 94 provided in the first portion 74a of the intermediate-pressure steam line 74 is a relatively small second opening degree B2 (about 25% opening degree as an example in FIG. 3).

[0062] At time t2 after the rotational speed of the steam turbine 10 reaches the rated rotational speed, the respective bypass valves (such as the high-pressure bypass valve 83 and the intermediate-pressure bypass valve 85) are closed, and the flow rate control by each steam valve (such as the high-pressure steam valve 22 and the intermediate-pressure steam valve 24) is started. Thereafter, at time t3, a predetermined load (100% load of the rating in the figure) is reached, and from here, the load operation (steady operation) at the predetermined load is started.

[0063] When the flow rate control by each steam valve (such as the high-pressure steam valve 22 and the intermediate-pressure steam valve 24) is started at time t2, the pressure at the junction point A stabilizes. The control device 112 increases the opening degree of the pressure regulating valve 94 to a predetermined first opening degree B1 (100% opening degree as an example in FIG. 3) at this timing (time t2). After the opening degree of the pressure regulating valve 94 reaches the first opening degree B1, the control device 112 maintains the opening degree of the pressure regulating valve 94 at the first opening degree B1 during the load operation at the specified load of the steam turbine 10 (that is, between time t5 and t6).

[0064] In this way, by maintaining the pressure regulating valve 94 at a relatively small predetermined second opening degree B2 during a period in which the pressure fluctuation at the confluence point A is relatively large until the time t2 at the start-up when the steam turbine facility 100 shifts from no-load operation to load operation, the pressure in the medium-pressure drum 54 (the solid line in the chart of FIG. 3) is less likely to be affected by the pressure fluctuation at the confluence point A during this period. Therefore, the pressure fluctuation of the medium-pressure drum 54 can be suppressed, and thus the fluctuation of the water level of the medium-pressure drum 54 can be suppressed.

[0065] Incidentally, if the pressure regulating valve 94 is not provided in the first portion 74a of the medium-pressure steam line 74, the pressure of the medium-pressure drum 54 (the broken line in the chart of FIG. 3) fluctuates greatly under the influence of the pressure fluctuation at the confluence point A, and thus the water level of the medium-pressure drum 54 also fluctuates greatly. In this case, the steam turbine facility 100 may be emergently stopped due to the rapid fluctuation of the water level of the medium-pressure drum 54.

[0066] On the other hand, in the above-described embodiment, as described above, since the fluctuation of the water level of the medium-pressure drum 54 can be suppressed, the emergency stop caused by the rapid fluctuation of the water level of the medium-pressure drum 54 can be suppressed. Therefore, the steam turbine facility 100 can be operated more stably.

[0067] In the embodiment shown in FIG. 3, the control device 112 increases the opening degree at a relatively low rate (time t2 to t4) until the opening degree of the pressure regulating valve 94 reaches the opening degree B3 (where B2 < B3 < B1, and B3 is, for example, 50%) from the second opening degree B2. Further, the control device 112 increases the opening degree at a relatively high rate (t4 to t5) until the opening degree of the pressure regulating valve 94 reaches the first opening degree B1 from the opening degree B3.

[0068] In this way, by increasing the opening degree at a relatively low rate in a relatively small opening degree region of the pressure regulating valve 94, even when a valve (such as a butterfly valve) with high sensitivity in the small opening degree region is adopted as the pressure regulating valve 94, the influence on the pressure of the medium-pressure drum 54 due to the change in the opening degree of the pressure regulating valve 94 can be suppressed.

[0069] On the other hand, when a valve (such as a butterfly valve) with not so high sensitivity in the fully open region is adopted in this way, the opening degree of the pressure regulating valve 94 can be quickly increased by increasing the opening degree at a relatively high rate in a relatively large opening degree region of the pressure regulating valve 94.

[0070] In this way, in the present embodiment, instead of controlling the opening degree of the pressure regulating valve 94 based on pressure, it is controlled based on a predetermined schedule (for example, based on the opening and closing timings of other valves, the opening degree of the pressure regulating valve 94, etc.). Therefore, by simple control, the pressure fluctuation and water level fluctuation of the medium pressure drum 54 can be appropriately suppressed. Further, this makes it easier to appropriately control the steam pressure of the medium pressure steam line 74 by the medium pressure steam valve 24.

[0071] In the chart of FIG. 3, at time t6, in order to stop the steam turbine 10, the decrease in the load of the steam turbine 10 is started. Also, at time t6, the pressure control of the opening degrees of the bypass valves (such as the high pressure bypass valve 83 and the medium pressure bypass valve 85) is started. Then, the ventilator valve 91 is opened. Further, after time t6, in order to stop the gas turbine 40, the decrease in the load of the gas turbine 40 is started.

[0072] At time t6, the control device 112 decreases the opening degree of the pressure regulating valve 94 from the first opening degree B1 to the second opening degree B2 (time t6 to t7). The control device 112 may decrease the opening degree of the pressure regulating valve 94 at a predetermined rate.

[0073] In this way, by maintaining the pressure regulating valve 94 at a relatively small predetermined second opening degree B2 during the period from time t6 to t7 when the steam turbine facility 100 is stopped and shifting from the load operation to the no-load operation, during this period, the pressure in the medium pressure drum 54 is less likely to be affected by the pressure fluctuation at the confluence point A. For this reason, the pressure fluctuation of the medium pressure drum 54 can be suppressed, and thus the fluctuation of the water level of the medium pressure drum 54 can be suppressed.

[0074] After time t7, the rotational speeds of the steam turbine 10 and the gas turbine 40 decrease to zero, and the plant is stopped.

[0075] FIG. 4 and FIG. 5 are charts showing an example of the time change in the opening degree of the pressure regulating valve 94 in the GTCC plant 1 including the above-described steam turbine facility 100 (steam turbine system 110), respectively. In the charts of FIGS. 4 and 5, the horizontal axis represents time, and the vertical axis represents the opening degree of the pressure regulating valve 94.

[0076] In the embodiments shown in FIGS. 4 and 5, the load is cut off during the load operation of the steam turbine facility 100 (times t11 and t21). In the embodiment shown in FIG. 4, the load is cut off at time t11 during the load operation at the rated load. In the embodiment shown in FIG. 5, the load is cut off at time t21 while the load is being increased to the rated load.

[0077] The control device 112 holds the opening degree of the pressure regulating valve 94 as it is for a specified length of time (times t11 to t12, times t21 to t22) from the times t11 and t21 when the load is cut off. Thereby, during this period, a rapid pressure fluctuation in the medium-pressure steam line 74 due to a change in the opening degree of the pressure regulating valve 94 can be suppressed. Therefore, it becomes easier to appropriately control the steam pressure in the medium-pressure steam line 74.

[0078] Thereafter, the opening degree of the pressure regulating valve 94 is decreased at a relatively large rate until it reaches the predetermined opening degree B3 (times t12 to t13, times t22 to t23). Subsequently, the opening degree of the pressure regulating valve 94 is decreased at a relatively small rate until it reaches the predetermined second opening degree B2 (times t13 to t14, times t23 to t24).

[0079] In this way, when the load is cut off in the steam turbine facility 100, after holding the opening degree of the pressure regulating valve 94 for a specified length of time, and then decreasing it to the second range based on a predetermined schedule, a rapid pressure fluctuation in the medium-pressure steam line 74 due to a change in the opening degree of the pressure regulating valve 94 can be suppressed during this period. Thereby, it becomes easier to appropriately control the steam pressure in the medium-pressure steam line 74.

[0080] Note that after a time period of a specified length from the times t11 and t21 when the load is interrupted and after the opening degree of the pressure regulating valve 94 is maintained (after the times t12 and t22), the gas turbine 40 may be extinguished. In this case, the gas turbine 40 is reignited thereafter.

[0081] And after a time period of a specified length from when the opening degree of the pressure regulating valve 94 becomes the second opening degree B2 (times t14 to t15, times t24 to t25), the opening degree of the pressure regulating valve 94 is maintained at the second opening degree B2.

[0082] Thereafter, the control device 112 increases the opening degree of the pressure regulating valve 94 to the predetermined first opening degree B1. After the opening degree of the pressure regulating valve 94 reaches the first opening degree B1 (that is, from the times t17 and t27), during the load operation at the specified load of the steam turbine 10, the control device 112 maintains the opening degree of the pressure regulating valve 94 at the first opening degree B1.

[0083] In this way, during the period when the steam turbine facility 100 shifts from no-load operation (load interruption) to load operation (the period when the pressure fluctuation at the confluence point A is relatively large), by maintaining the pressure regulating valve 94 at the relatively small predetermined second opening degree B2, during this period, the pressure in the medium-pressure drum 54 is less likely to be affected by the pressure fluctuation at the confluence point A. Therefore, the pressure fluctuation of the medium-pressure drum 54 can be suppressed, and thus, the fluctuation of the water level of the medium-pressure drum 54 can be suppressed.

[0084] In the embodiments shown in FIGS. 4 and 5, the control device 112 increases the opening degree at a relatively low rate until the opening degree of the pressure regulating valve 94 becomes the opening degree B3 (where B2 < B3 < B1, and B3 is, for example, 50%) from the second opening degree B2 (times t15 to t16, times t25 to t26). Also, the control device 112 increases the opening degree at a relatively high rate until the opening degree of the pressure regulating valve 94 becomes the first opening degree B1 from the opening degree B3 (t16 to t17, t26 to t27).

[0085] In this way, by increasing the opening degree at a relatively low rate in the relatively small opening degree region of the pressure regulating valve 94, even when a valve (such as a butterfly valve) with high sensitivity in the small opening degree region is adopted as the pressure regulating valve 94, the influence on the pressure of the medium-pressure drum 54 due to the change in the opening degree of the pressure regulating valve 94 can be suppressed.

[0086] The content described in each of the above embodiments can be understood as follows, for example.

[0087] (1) The control device for a steam turbine facility according to at least one embodiment of the present invention is a control device for controlling a steam turbine facility including a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine, wherein the steam turbine facility includes a medium-pressure steam line for guiding steam from a medium-pressure drum to the medium-pressure turbine, and a pressure regulating valve provided in a first portion on the upstream side of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges in the medium-pressure steam line, and is configured to maintain the opening degree of the pressure regulating valve within a first range during load operation at a predetermined load of the steam turbine facility, and maintain the opening degree of the pressure regulating valve within a second range having a smaller opening degree than the first range during a transition of the operating state between no-load operation and load operation of the steam turbine facility. is configured as such.

[0088] When shifting the operating state between the no-load operation and the load operation (steady operation) at a predetermined load of the steam turbine facility (for example, at startup of the steam turbine facility), due to changes in steam pressure, opening and closing of various valves, etc., the pressure fluctuation at the confluence point where steam from the high-pressure drum merges in the intermediate-pressure steam line is relatively large. According to the configuration of (1) above, a pressure regulating valve is provided in the first part of the intermediate-pressure steam line upstream of the above-mentioned confluence point, and during a period when the pressure fluctuation at the confluence point is relatively large (i.e., when the operating state of the steam turbine facility is shifted), the opening degree of the pressure regulating valve is maintained within a relatively small second range. Therefore, during this period, the pressure in the intermediate-pressure drum is less likely to be affected by the pressure fluctuation at the confluence point, so that the fluctuation of the water level in the intermediate-pressure drum can be suppressed. Thereby, for example, an emergency stop caused by a sudden change in the water level of the intermediate-pressure drum can be suppressed, and the steam turbine facility can be operated more stably.

[0089] (2) In some embodiments, in the configuration of (1) above, the steam turbine facility is an intermediate-pressure bypass valve provided in an intermediate-pressure bypass line that branches from the second part of the intermediate-pressure steam line downstream of the confluence point and is connected to the condenser without passing through the intermediate-pressure turbine and the low-pressure turbine, or a ventilator valve provided in a ventilation line that branches from a high-pressure discharge line for guiding steam from the outlet of the high-pressure turbine to the intermediate-pressure steam line and is connected to the condenser without passing through the intermediate-pressure turbine and the low-pressure turbine is included.

[0090] According to the configuration of (2) above, when the operating state of the steam turbine facility is shifted (such as at startup), the opening and closing operation of the intermediate-pressure bypass valve or the ventilator valve tends to increase the pressure fluctuation at the above-mentioned confluence point in the intermediate-pressure steam line. Even in such a case, according to the configuration of (1) above, during a period when the pressure fluctuation at the confluence point becomes relatively large (when the operating state of the steam turbine facility is shifted), the pressure in the intermediate-pressure drum is less likely to be affected by the pressure fluctuation at the confluence point, so that the fluctuation of the water level in the intermediate-pressure drum can be suppressed.

[0091] (3) In some embodiments, in the configuration of (1) or (2) above, the second range of the opening degree of the pressure regulating valve is an opening degree range such that the pressure at a site upstream of the pressure regulating valve in the first part of the medium-pressure steam line is greater than the pressure at the confluence point of the medium-pressure steam line.

[0092] According to the configuration of (3) above, during a period when the pressure fluctuation at the confluence point is relatively large (when the operating state of the steam turbine facility transitions), the opening degree of the pressure regulating valve is maintained within an opening degree range such that the pressure at a site upstream of the pressure regulating valve in the first part of the medium-pressure steam line is greater than the pressure at the confluence point of the medium-pressure steam line. Therefore, during this period, the pressure in the medium-pressure drum is less susceptible to the influence of the pressure fluctuation at the confluence point, so that the fluctuation of the water level in the medium-pressure drum can be effectively suppressed.

[0093] (4) In some embodiments, in any of the configurations of (1) to (3) above, when the operating state of the steam turbine facility transitions, the opening degree of the pressure regulating valve is configured to be maintained at a second opening degree within the second range.

[0094] According to the configuration of (4) above, during a period when the pressure fluctuation at the confluence point is relatively large (when the operating state of the steam turbine facility transitions), the opening degree of the pressure regulating valve is maintained at a second opening degree within a relatively small second range. Therefore, by simple opening degree control of the pressure regulating valve, the fluctuation of the water level in the medium-pressure drum can be effectively suppressed during this period.

[0095] (5) In some embodiments, in any of the configurations of (1) to (4) above, when the steam turbine facility is in load operation, the opening degree of the pressure regulating valve is configured to be maintained at a first opening degree within the first range.

[0096] According to the configuration of (5) above, during the load operation (steady operation) at the rated load of the steam turbine facility, since the opening degree of the pressure regulating valve is maintained at the first opening degree, the opening degree control of the pressure regulating valve can be made simpler.

[0097] (6) In some embodiments, in any of the configurations of (1) to (5) above, When the operating state of the steam turbine facility transitions, it is at the start-up or shutdown of the steam turbine facility.

[0098] According to the configuration of (6) above, At the start-up or shutdown of the steam turbine facility, which is a period when the pressure fluctuation at the above-mentioned confluence point is relatively large, according to the configuration of (1) above, the pressure in the intermediate-pressure drum is less likely to be affected by the pressure fluctuation at the confluence point, so that the fluctuation of the water level in the intermediate-pressure drum can be suppressed.

[0099] (7) In some embodiments, in any of the configurations of (1) to (6) above, When the operating state of the steam turbine facility transitions from the no-load operation to the load operation, the opening degree of the pressure regulating valve is configured to increase from the second range to the first range based on a predetermined schedule.

[0100] According to the configuration of (7) above, when the operating state of the steam turbine facility transitions from the no-load operation to the load operation, by appropriately increasing the opening degree of the pressure regulating valve from the second range to the first range based on a predetermined schedule, a sudden pressure fluctuation in the intermediate-pressure steam line due to the change in the opening degree of the pressure regulating valve can be suppressed. Thereby, it becomes easier to appropriately control the steam pressure in the intermediate-pressure steam line.

[0101] (8) In some embodiments, in any of the configurations of (1) to (7) above, When the operating state of the steam turbine facility transitions from the load operation to the no-load operation, the opening degree of the pressure regulating valve is configured to decrease from the first range to the second range based on a predetermined schedule.

[0102] According to the configuration of (8) above, when the operating state of the steam turbine facility shifts from a load operation to a no-load operation, by appropriately reducing the opening degree of the pressure regulating valve from the first range to the second range based on a predetermined schedule, it is possible to suppress a sudden pressure fluctuation in the medium-pressure steam line due to a change in the opening degree of the pressure regulating valve. As a result, it becomes easier to appropriately control the steam pressure in the medium-pressure steam line.

[0103] (9) In some embodiments, in any of the configurations of (1) to (8) above, when the load is interrupted during the load operation of the steam turbine facility, the opening degree of the pressure regulating valve is configured to be held for a specified length of time.

[0104] According to the configuration of (9) above, when the load is interrupted during the load operation of the steam turbine facility, since the opening degree of the pressure regulating valve is held for a specified length of time, it is possible to suppress a sudden pressure fluctuation in the medium-pressure steam line due to a change in the opening degree of the pressure regulating valve during this period. As a result, it becomes easier to appropriately control the steam pressure in the medium-pressure steam line.

[0105] (10) In some embodiments, in the configuration of (9) above, when the load is interrupted during the load operation of the steam turbine facility, the opening degree of the pressure regulating valve is configured to be decreased to the second range based on a predetermined schedule after being held for a specified length of time.

[0106] According to the configuration of (10) above, when the load is interrupted during the load operation of the steam turbine facility, since the opening degree of the pressure regulating valve is held for a specified length of time and then decreased to the second range based on a predetermined schedule, it is possible to suppress a sudden pressure fluctuation in the medium-pressure steam line due to a change in the opening degree of the pressure regulating valve during this period. As a result, it becomes easier to appropriately control the steam pressure in the medium-pressure steam line.

[0107] (11) The steam turbine system according to at least one embodiment of the present invention includes a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, an intermediate-pressure steam line for guiding steam from an intermediate-pressure drum to the intermediate-pressure turbine, a pressure regulating valve provided in a first portion of the intermediate-pressure steam line upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges, steam turbine equipment including, a control device configured to control the steam turbine equipment according to any one of the above (1) to (10), and includes.

[0108] According to the configuration of the above (11), a pressure regulating valve is provided in a first portion of the intermediate-pressure steam line upstream of the above-mentioned confluence point, and during a period when the pressure fluctuation at the confluence point is relatively large (i.e., when the operating state of the steam turbine equipment transitions), the opening degree of the pressure regulating valve is maintained within a relatively small second range. Therefore, during this period, the pressure in the intermediate-pressure drum is less affected by the pressure fluctuation at the confluence point, so that the fluctuation of the water level in the intermediate-pressure drum can be suppressed. As a result, for example, an emergency stop caused by a sudden fluctuation in the water level of the intermediate-pressure drum can be suppressed, and the steam turbine equipment can be operated more stably.

[0109] (12) A control method for steam turbine equipment according to at least one embodiment of the present invention is a control method for controlling steam turbine equipment including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, and the steam turbine equipment includes an intermediate-pressure steam line for guiding steam from an intermediate-pressure drum to the intermediate-pressure turbine, a pressure regulating valve provided in a first portion of the intermediate-pressure steam line upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges, and includes, When operating at the rated load of the steam turbine facility, maintaining the opening degree of the pressure regulating valve within a first range; When transitioning the operating state between no-load operation and load operation of the steam turbine facility, maintaining the opening degree of the pressure regulating valve within a second range that is smaller in opening degree than the first range; It includes.

[0110] According to the method of (12) above, a pressure regulating valve is provided in the first portion of the medium-pressure steam line upstream of the above-mentioned confluence point, and during a period when the pressure fluctuation at the confluence point is relatively large (that is, when transitioning the operating state of the steam turbine facility), the opening degree of the pressure regulating valve is maintained within a relatively small second range. Therefore, during this period, the pressure in the medium-pressure drum is less likely to be affected by the pressure fluctuation at the confluence point, so the fluctuation of the water level in the medium-pressure drum can be suppressed. As a result, for example, an emergency stop caused by a sudden fluctuation in the water level of the medium-pressure drum can be suppressed, and the steam turbine facility can be operated more stably.

[0111] (13) The control program of the steam turbine facility according to at least one embodiment of the present invention is A control program for controlling a steam turbine facility including a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine, The steam turbine facility is A medium-pressure steam line for guiding steam from the medium-pressure drum to the medium-pressure turbine, A pressure regulating valve provided in the first portion of the medium-pressure steam line upstream of the confluence point where steam from the high-pressure drum for generating steam supplied to the high-pressure turbine merges, It includes, To the computer, When operating at the rated load of the steam turbine facility, a procedure for maintaining the opening degree of the pressure regulating valve within a first range; When transitioning the operating state between no-load operation and load operation of the steam turbine facility, a procedure for maintaining the opening degree of the pressure regulating valve within a second range that is smaller in opening degree than the first range; It is configured to cause the above to be executed.

[0112] According to the program of (13) above, a pressure regulating valve is provided in the first part of the medium-pressure steam line upstream of the above-mentioned confluence point, and during a period when the pressure fluctuation at the confluence point is relatively large (i.e., when the operating state of the steam turbine facility is changing), the opening degree of the pressure regulating valve is maintained within a relatively small second range. Therefore, during this period, the pressure in the medium-pressure drum is less likely to be affected by the pressure fluctuation at the confluence point, so that the fluctuation of the water level in the medium-pressure drum can be suppressed. Thereby, for example, an emergency stop caused by a sudden fluctuation of the water level in the medium-pressure drum can be suppressed, and the steam turbine facility can be operated more stably.

[0113] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and also includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

[0114] In this specification, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent a state of being relatively displaced with tolerances or at an angle or distance such that the same function can be obtained. For example, expressions indicating that things such as "identical", "equal", and "homogeneous" are in an equal state not only strictly represent an equal state, but also represent a state in which there are tolerances or differences such that the same function can be obtained. Also, in this specification, expressions indicating shapes such as a rectangular shape or a cylindrical shape not only represent shapes such as a rectangular shape or a cylindrical shape in a geometrically strict sense, but also represent shapes including concave and convex portions, chamfered portions, etc. within a range where the same effect can be obtained. Also, in this specification, the expression of a component "comprising", "including", or "having" is not an exclusive expression excluding the existence of other components.

Explanation of Reference Numerals

[0115] 1 GTCC Plant 4 Generator 10 Steam Turbine 12 High-Pressure Turbine 14 Medium-Pressure Turbine 16 Low-Pressure Turbine 18 Condenser 22 High-Pressure Steam Valve 24 Medium-Pressure Steam Valve 26 Low-Pressure Steam Valve 40 Gas Turbine 42 Compressor 44 Combustor 46 Turbine 48 Exhaust Gas 50 Heat Recovery Boiler 52 High-Pressure Drum 54 Medium-Pressure Drum 56 Low-Pressure Drum 64 Superheater 65 Reheater 66 Superheater 72 High-Pressure Steam Line 73 High-Pressure Discharge Line 74 Medium-Pressure Steam Line 74a Part 1 74b Part 2 75 Medium-Pressure Discharge Line 76 Low-Pressure Steam Line 78 Feed Water Line 82 High-Pressure Bypass Line 83 High-Pressure Bypass Valve 84 Medium-Pressure Bypass Line 85 Medium-Pressure Bypass Valve 86 Low-Pressure Bypass Line 87 Low-Pressure Bypass Valve 90 Vent Line 91 Ventilator Valve 92 Check Valve 94 Pressure Regulating Valve 96 Check Valve 100 Steam Turbine Equipment 110 Steam Turbine System 112 Control Device A Junction Point

Claims

1. A control device for controlling a steam turbine facility including a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine, wherein the steam turbine facility includes a medium-pressure steam line for guiding steam from a medium-pressure drum to the medium-pressure turbine, a pressure regulating valve provided in a first portion of the medium-pressure steam line upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges, and includes during load operation at a predetermined load of the steam turbine facility, maintaining the opening degree of the pressure regulating valve within a first range, and during a transition of the operating state between no-load operation and load operation of the steam turbine facility, maintaining the opening degree of the pressure regulating valve at a fixed second opening degree within a second range having a smaller opening degree than the first range configured to be a control device for a steam turbine facility.

2. wherein the steam turbine facility includes a ventilator valve provided in a vent line branched from a high-pressure discharge line for guiding steam from the outlet of the high-pressure turbine to the medium-pressure steam line and connected to the condenser without passing through the medium-pressure turbine and the low-pressure turbine, and includes configured such that when the opening / closing state of the ventilator valve is changed during the transition of the operating state, the opening degree of the pressure regulating valve is maintained at the second opening degree The control device for a steam turbine facility according to claim 1.

3. The steam turbine facility includes a medium-pressure bypass valve provided in a medium-pressure bypass line branched from a second portion of the medium-pressure steam line downstream of the confluence point and connected to the condenser without passing through the medium-pressure turbine and the low-pressure turbine, configured such that during the transition of the operating state, the opening degree of the medium-pressure bypass valve is adjusted based on the pressure of the medium-pressure steam line, and when the opening / closing state of the ventilator valve is changed, the opening degree of the pressure regulating valve is maintained at the second opening degree The control device for a steam turbine facility according to claim 2.

4. The second range of the opening degree of the pressure regulating valve is an opening degree range such that the pressure at a portion of the first portion of the medium-pressure steam line upstream of the pressure regulating valve is greater than the pressure at the confluence point of the medium-pressure steam line. The control device for a steam turbine facility according to any one of claims 1 to 3.

5. configured such that during the load operation of the steam turbine facility, the opening degree of the pressure regulating valve is maintained at a first opening degree within the first range The control device for a steam turbine facility according to any one of claims 1 to 4.

6. When shifting the operating state of the steam turbine facility, it is at the time of starting up the steam turbine facility The control device for a steam turbine facility according to any one of claims 1 to 5.

7. When the operating state of the steam turbine facility shifts from the no-load operation to the load operation, the opening degree of the pressure regulating valve is configured to increase from the second range to the first range based on a predetermined schedule The control device for a steam turbine facility according to any one of claims 1 to 6.

8. When the operating state of the steam turbine facility shifts from the load operation to the no-load operation, the opening degree of the pressure regulating valve is configured to decrease from the first range to the second range based on a predetermined schedule The control device for a steam turbine facility according to any one of claims 1 to 7.

9. When the load is cut off during the load operation of the steam turbine facility, the opening degree of the pressure regulating valve is configured to be held for a specified length of time The control device for a steam turbine facility according to any one of claims 1 to 8.

10. When the load is cut off during the load operation of the steam turbine facility, after the opening degree of the pressure regulating valve is held for a specified length of time, it is configured to decrease to the second range based on a predetermined schedule The control device for a steam turbine facility according to claim 9.

11. A high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, An intermediate-pressure steam line for guiding steam from an intermediate-pressure drum to the intermediate-pressure turbine, A pressure regulating valve provided in a first portion upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine joins in the intermediate-pressure steam line, A steam turbine facility including, The control device according to any one of claims 1 to 10 configured to control the steam turbine facility, A steam turbine system comprising.

12. A control method for controlling a steam turbine facility including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, The steam turbine facility is An intermediate-pressure steam line for guiding steam from an intermediate-pressure drum to the intermediate-pressure turbine, A pressure regulating valve provided in a first portion upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine joins in the intermediate-pressure steam line, Including, When operating at the rated load of the steam turbine facility, maintaining the opening degree of the pressure regulating valve within a first range; When transitioning the operating state between no-load operation and load operation of the steam turbine facility, maintaining the opening degree of the pressure regulating valve at a fixed second opening degree within a second range that is smaller in opening degree than the first range; Comprising A control method for a steam turbine facility.

13. A control program for controlling a steam turbine facility including a high-pressure turbine, an intermediate-pressure turbine, and a low-pressure turbine, The steam turbine facility is An intermediate-pressure steam line for guiding steam from an intermediate-pressure drum to the intermediate-pressure turbine, A pressure regulating valve provided in a first portion upstream of a confluence point where steam from a high-pressure drum for generating steam supplied to the high-pressure turbine merges in the intermediate-pressure steam line; Including To a computer, When operating at the rated load of the steam turbine facility, a procedure for maintaining the opening degree of the pressure regulating valve within a first range; When transitioning the operating state between no-load operation and load operation of the steam turbine facility, a procedure for maintaining the opening degree of the pressure regulating valve at a fixed second opening degree within a second range that is smaller in opening degree than the first range; For executing A control program for a steam turbine facility.

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