Plant control device, plant control method and plant control program

Abstract

To prevent a flow rate of a booster pump from becoming excessive relative to each water supply system by using a simple device configuration.SOLUTION: A plant to be controlled by a plant control device includes: a boiler for generating steam by using waste heat of a gas turbine; a booster pump for generating first supply water and second supply water having a pressure higher than that of the first supply water by boosting a pressure of condensed water generated from steam; a first water supply system for supplying the first supply water to a first steam generation drum; and a second water supply system for supplying the second supply water to a second steam generation drum. The plant control device includes: a booster pump control section for controlling the booster pump; and a flow rate detector for detecting a flow rate of the second supply water. The booster pump control section stops the booster pump on the condition that a flow rate detected by the flow rate detector exceeds a reference value. The reference value is set to a first reference value corresponding to a rated flow rate of the second supply water after start of the gas turbine, and is set to a second reference value smaller than the first reference value before start of the gas turbine.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a plant control device, a plant control method, and a plant control program.

Background Art

[0002] There is known a plant including a steam generation drum capable of generating steam to be supplied to a steam turbine by heating feed water from a feed water system using exhaust heat from a gas turbine. In this type of plant, steam that has completed work in the steam turbine is returned to condensate, the condensate is pressurized by a booster pump, and the feed water discharged from the booster pump is supplied to the steam generation drum by the feed water system. Here, when the feed water discharged from the booster pump becomes an excessive flow rate, there is a risk that problems such as damage to the mechanical seal or generation of a gap in the housing may occur in the booster pump. Therefore, it is effective to detect the flow rate of the feed water discharged from the booster pump and stop the booster pump by interlock control when the flow rate exceeds a reference value, thereby preventing an excessive flow rate in advance. For example, in Patent Document 1, although it is not interlock control for stopping the booster pump, a technique is disclosed in which the feed water flow rates in the feed water systems on the high-pressure side and the medium-pressure side of the booster pump are respectively detected, and the valve opening degrees arranged in the respective feed water systems are adjusted so that an excessive flow rate does not occur in the booster pump.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, control is performed to prevent the booster pump from having an excessive flow rate based on the results of comparing the respective detected values of the flow rates for each water supply system on the high-pressure side and the medium-pressure side of the booster pump with the reference values during normal operation. Such control to prevent the booster pump from having an excessive flow rate mainly targets the normal operation of the gas turbine. However, as a result of the inventor's verification of past malfunction cases due to the excessive flow rate of the booster pump, it has been found that the excessive flow rate of the booster pump often occurs at stages before normal operation, such as during the water filling of the steam generation drum or during the system startup preparation. Further, in Patent Document 1, since it is necessary to install flow meters for detecting the flow rate in each water supply system on the high-pressure side and the medium-pressure side, the cost increases.

[0005] At least one embodiment of the present disclosure has been made in view of the above circumstances, and an object thereof is to provide a plant control device, a plant control method, and a plant control program that can prevent a booster pump from having an excessive flow rate for each water supply system with a simple device configuration.

Means for Solving the Problems

[0006] A plant control device according to at least one embodiment of the present disclosure is, in order to solve the above problems, a boiler for generating steam using the exhaust heat of a gas turbine, a booster pump for generating first feed water and second feed water having a higher pressure than the first feed water by boosting the condensate generated from the steam, a first water supply system for supplying the first feed water to a first steam generation drum, a second water supply system for supplying the second feed water to a second steam generation drum, a plant control device for controlling a plant including a second feed water flow rate acquisition unit for acquiring the flow rate of the second feed water, a booster pump control unit for controlling the booster pump, and including The boost pump control unit stops the boost pump on the condition that the flow rate acquired by the second feed water flow rate acquisition unit exceeds a reference value. The reference value is set to a first reference value corresponding to the rated flow rate of the second feed water after the start-up of the gas turbine, and is set to a second reference value lower than the first reference value before the start-up of the gas turbine.

[0007] In order to solve the above problems, a plant control method according to at least one embodiment of the present disclosure a boiler for generating steam using exhaust heat of a gas turbine; a boost pump for generating first feed water and second feed water having a higher pressure than the first feed water by boosting the condensate generated from the steam; a first feed water system for supplying the first feed water to a first steam generation drum; a second feed water system for supplying the second feed water to a second steam generation drum; A plant control method for controlling a plant including: a step of acquiring a flow rate of the second feed water; a step of stopping the boost pump on the condition that the flow rate exceeds a reference value; comprising The reference value is set to a first reference value corresponding to the rated flow rate of the second feed water after the start-up of the gas turbine, and is set to a second reference value lower than the first reference value before the start-up of the gas turbine.

[0008] In order to solve the above problems, a plant control program according to at least one embodiment of the present disclosure a boiler for generating steam using exhaust heat of a gas turbine; a boost pump for generating first feed water and second feed water having a higher pressure than the first feed water by boosting the condensate generated from the steam; a first feed water system for supplying the first feed water to a first steam generation drum; a second feed water system for supplying the second feed water to a second steam generation drum; A plant control program for controlling a plant comprising: a computer device, a step of acquiring the flow rate of the second feed water; a step of stopping the booster pump on condition that the flow rate exceeds a reference value; is executable, wherein the reference value is set to a first reference value corresponding to the rated flow rate of the second feed water after startup of the gas turbine, and is set to a second reference value lower than the first reference value before startup of the gas turbine.

Advantages of the Invention

[0009] According to at least one embodiment of the present disclosure, it is possible to provide a plant control device, a plant control method, and a plant control program that can prevent the booster pump from having an excessive flow rate for each water supply system with a simple device configuration.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Modes for Carrying Out the Invention

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

[0012] First, referring to FIG. 1, the configuration of a combined cycle plant 1, which is an example of a plant to be controlled by a plant control device 100 according to some embodiments, will be described. FIG. 1 is a schematic configuration diagram of a combined cycle plant 1 according to an embodiment.

[0013] The combined cycle plant 1 includes a gas turbine 10, a heat recovery boiler 20 for generating steam with the exhaust gas EG from the gas turbine 10, a steam turbine 60 that can be driven by the steam from the heat recovery boiler 20, and a condenser 40 for returning the steam from the steam turbine 60 to water.

[0014] The gas turbine 10 includes a compressor 11 for compressing combustion air, and a turbine 15 driven by combustion gas generated by mixing and burning the combustion air compressed by the compressor 11 and fuel supplied from a fuel supply system. The rotors of the compressor 11 and the turbine 15 are connected to each other to form a gas turbine rotor 19.

[0015] The steam turbine 60 includes a high-pressure steam turbine HP, an intermediate-pressure steam turbine IP, and a low-pressure steam turbine LP. The high-pressure steam turbine HP, the intermediate-pressure steam turbine IP, and the low-pressure steam turbine LP have a steam turbine rotor 61 by connecting their respective rotating shafts to each other. The steam turbine rotor 61 is integrally connected to the aforementioned gas turbine rotor 19. The steam that has completed its work in the steam turbine 60 is returned to condensate in the condenser 40.

[0016] The condensate of the condenser 40 can be supplied to the exhaust heat recovery boiler 20 via the condensate supply line 62. A low-pressure feed water pump 63 is provided in the condensate supply line 62, and the amount of condensate supplied to the exhaust heat recovery boiler 20 can be adjusted. Further, a desuperheater 64 is provided on the downstream side of the low-pressure feed water pump 63 in the condensate supply line 62, and the feed water temperature to the exhaust heat recovery boiler 20 can be adjusted.

[0017] In addition, a makeup water tank 42 is connected to the condenser 40 via a makeup water supply line 41. A makeup water supply pump 39 is installed in the makeup water supply line 41, and when the condensate is insufficient in the condenser 40, makeup water can be supplied from the makeup water tank 42.

[0018] The exhaust heat recovery boiler 20 is a boiler for generating steam using the exhaust heat of the gas turbine 10. That is, the exhaust heat recovery boiler 20 has a configuration for recovering and effectively utilizing the heat (exhaust heat) contained in the exhaust gas EG from the gas turbine 10. The exhaust heat recovery boiler 20 includes a low-pressure economizer 21, a low-pressure evaporator 22, a high-pressure primary economizer 23, a medium-pressure economizer 24, a medium-pressure evaporator 25, a low-pressure superheater 26, a high-pressure secondary economizer 27, a medium-pressure superheater 28, a high-pressure evaporator 29, a high-pressure primary superheater 30, a primary reheater 31, a secondary reheater 32, and a high-pressure secondary superheater 33 as a configuration for utilizing the heat recovered from the exhaust gas EG.

[0019] In addition, in the present embodiment, an example of a system in which two high-pressure superheaters and reheaters are provided respectively is shown, but the present invention is not limited to this, and the number of high-pressure superheaters and reheaters may be three or more respectively.

[0020] In addition, the exhaust gas after heat is recovered in the exhaust heat recovery boiler 20 is discharged to the outside from the chimney 34.

[0021] In the heat recovery boiler 20, the feed water (condensate) from the condenser 40 is first heated by the low-pressure economizer 21. At least a part of the feed water heated by the low-pressure economizer 21 is stored in the low-pressure drum 44. A low-pressure evaporator 22 is connected to the low-pressure drum 44, and it is possible to generate steam from at least a part of the water stored in the low-pressure drum 44. The steam generated by the low-pressure evaporator 22 is returned to the low-pressure drum 44.

[0022] Also, the feed water (condensate) heated by the low-pressure economizer 21 is supplied to the booster pump 43. The booster pump 43 is a boiler feed pump (BFP) composed of a high-pressure feed pump 45 and an intermediate-pressure feed pump 46. The intermediate-pressure feed pump 46 generates a first feed water SW1 having a first pressure P1 by boosting the feed water (condensate), and the high-pressure feed pump 45 generates a second feed water SW2 having a second pressure P2 higher than the first pressure P1 by boosting the feed water (condensate). The second feed water SW2 boosted to the second pressure P2 by the high-pressure feed pump 45 is supplied to the high-pressure drum 47, which is a second steam generation drum, via a second feed water system SS2 including a high-pressure primary economizer 23 and a high-pressure secondary economizer 27. In the second feed water system SS2, the second feed water SW2 is heated by the high-pressure primary economizer 23 and the high-pressure secondary economizer 27 and then supplied to the high-pressure drum 47. The first feed water SW1 boosted to the first pressure P1 by the intermediate-pressure feed pump 46 is supplied to the intermediate-pressure drum 48, which is a first steam generation drum, via a first feed water system SS1 including an intermediate-pressure economizer 24. In the first feed water system SS1, the first feed water SW1 is heated by the intermediate-pressure economizer 24 and then supplied to the intermediate-pressure drum 48.

[0023] The booster pump 43 is integrally composed of a high-pressure feed pump 45 and a medium-pressure feed pump 46. Specifically, the booster pump 43 has an introduction part 43a for introducing feed water (condensate heated by the low-pressure economizer 21) from the upstream side. The feed water introduced from the introduction part 43a is pressurized by the high-pressure feed pump 45 while passing through the second feed line 43b2, and is discharged as the second feed SW2 from the second feed discharge part 43c2 into the second feed water system SS2. Also, a first feed line 43b1 branches from the middle of the second feed line 43b2, and a part of the feed water introduced from the introduction part 43a is pressurized by the medium-pressure feed pump 46 and discharged as the first feed SW1 from the first feed discharge part 43c1 into the first feed water system SS1.

[0024] A high-pressure evaporator 29 is connected to the high-pressure drum 47, and it is possible to generate steam from at least a part of the water stored in the high-pressure drum 47. The steam generated in the high-pressure evaporator 29 is returned to the high-pressure drum 47. The steam extracted from the high-pressure drum 47 is superheated by the high-pressure primary superheater 30 and the high-pressure secondary superheater 33, and is supplied to the high-pressure steam turbine HP. A first desuperheater 49a is provided between the high-pressure primary superheater 30 and the high-pressure secondary superheater 33, and by controlling the desuperheating amount in the first desuperheater 49a, the steam temperature supplied to the high-pressure steam turbine HP can be appropriately adjusted.

[0025] The steam that has completed its work in the high-pressure steam turbine HP is heated by the primary reheater 31 and the secondary reheater 32, and then supplied to the medium-pressure steam turbine IP. A second desuperheater 49b is provided between the primary reheater 31 and the secondary reheater 32, and by controlling the desuperheating amount in the second desuperheater 49b, the steam temperature supplied to the medium-pressure steam turbine IP can be appropriately adjusted.

[0026] The medium-pressure drum 48 is connected to a medium-pressure evaporator 25 and is capable of generating steam from at least a part of the water stored in the medium-pressure drum 48. The steam generated by the medium-pressure evaporator 25 is returned to the medium-pressure drum 48. A part of the steam extracted from the medium-pressure drum 48 is heated by a medium-pressure superheater 28 and supplied to the outlet flow path of a high-pressure steam turbine HP, and then supplied to an intermediate-pressure steam turbine IP via a primary reheater 31 and a secondary reheater 32.

[0027] The low-pressure drum 44 is connected to a low-pressure evaporator 22 and is capable of generating steam from at least a part of the water stored in the low-pressure drum 44. The steam generated by the low-pressure evaporator 22 is returned to the low-pressure drum 44. A part of the steam extracted from the low-pressure drum 44 is heated by a low-pressure superheater 26 and supplied to the outlet flow path of an intermediate-pressure steam turbine IP, and then supplied to a low-pressure steam turbine LP. The steam that has completed work in the low-pressure steam turbine LP is returned to a condenser 40.

[0028] FIG. 2 is a schematic diagram schematically showing the peripheral configuration of the booster pump 43 in FIG. 1. The second feed water SW2 discharged from a high-pressure feed water pump 45 among the booster pumps 43 is supplied to a second feed water system SS2. The second feed water system SS2 includes a second feed water line 50 for supplying the second feed water SW2 discharged from the high-pressure feed water pump 45 to a downstream high-pressure primary economizer 23 and a high-pressure secondary economizer 27. A flow meter 51 for detecting the flow rate of the second feed water SW2 is installed at the outlet of the high-pressure feed water pump 45 in the second feed water line 50. Further, a BFP outlet motor-operated valve 52 for switching the supply / shutoff of the second feed water SW2 from the high-pressure feed water pump 45 is provided on the downstream side of the flow meter 51 in the second feed water line 50. Further, an ECO inlet motor-operated valve 53 for switching the supply / shutoff of the second feed water SW2 to the high-pressure primary economizer 23 and an ECO inlet control valve 54 for controlling the flow rate of the second feed water SW2 supplied to the medium-pressure economizer 24 are provided at the inlet of the high-pressure primary economizer 23 in the second feed water line 50.

[0029] Still, between the flowmeter 51 and the BFP outlet motor-operated valve 52 in the second water supply line, a minimum flow line 55 for ensuring the minimum flow rate of the second water supply SW2 when the BFP outlet motor-operated valve 52 is closed is connected. Also, between the ECO inlet motor-operated valve 53 and the ECO inlet control valve 54 in the second water supply line 50, a water injection line 56 for performing water injection for water filling of the medium-pressure carbonizer 24 during startup is connected. Further, on the upstream side of the ECO inlet motor-operated valve 53 in the second water supply line 50, a heat exchange medium supply line 57 for supplying a part of the second water supply SW2 as a heat exchange medium with the cooling air supplied to the gas turbine is connected.

[0030] The control device 100 is a control unit for controlling the booster pump 43 based on the detection result of the flowmeter 51, and is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium, etc. And a series of processes for realizing various functions are stored in a storage medium, etc. in the form of a program as an example. The CPU reads this program into the RAM, etc. and executes information processing and arithmetic processing, thereby realizing various functions. Still, the program may be applied in a form pre-installed in the ROM or other storage media, a form provided in a state stored in a computer-readable storage medium, a form distributed via wired or wireless communication means, etc. A computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, etc.

[0031] FIG. 3 is a block configuration diagram of the control device 100 in FIG. 2. As shown in FIG. 3, the control device 100 includes a second water supply flow rate acquisition unit 102, a gas turbine state determination unit 104, a condition determination unit 106, a reference value setting unit 108, and a booster pump control unit 110.

[0032] The second water supply flow rate acquisition unit 102 is a configuration for acquiring the flow rate F2 of the second water supply SW2. Specifically, the second water supply flow rate acquisition unit 102 acquires the flow rate F2 of the second water supply SW2 based on the detection value by the flow rate detector 51 provided in the second water supply line 50.

[0033] The gas turbine state determination unit 104 is a configuration for determining the state of the gas turbine 10. In the present embodiment, the gas turbine state determination unit 104 is configured to be able to determine whether the gas turbine 10 is in a state before startup or in a state after startup. Such determination of the state of the gas turbine 10 detects, for example, that the gas turbine 10 has started (is in a state after startup) based on an operation signal of the startup button of the gas turbine 10 or a startup signal from the control device, or determines that the gas turbine 10 has stopped (is in a state before startup) based on an operation signal of the stop button of the gas turbine 10 or a stop signal from the control device. As another example, the state of the gas turbine 10 may be determined based on information such as the rotational speed and output value of the gas turbine 10.

[0034] In addition, the gas turbine state determination unit 104 may determine that the gas turbine 10 is in the state when the state of the gas turbine 10 continues for a predetermined period. For example, when the period during which the determination criterion for the gas turbine 10 to be in the state before startup is satisfied continues for a predetermined period, the gas turbine state determination unit 104 outputs a determination result that the gas turbine 10 is in the state before startup.

[0035] The condition determination unit 106 is a configuration for determining the success or failure of a condition (hereinafter, appropriately referred to as a "stop condition") for stopping the booster pump 43 by comparing the flow rate F2 of the second water supply SW2 acquired by the second water supply flow rate acquisition unit 102 with a reference value Fref. The stop condition is determined to be established when the flow rate F exceeds the reference value Fref as a result of comparing the flow rate F2 acquired by the second water supply flow rate acquisition unit 102 with the reference value Fref set by the reference value setting unit 108.

[0036] The reference value setting unit 108 is a configuration for setting a reference value Fref used as a determination criterion in the condition determination unit 106. The reference value setting unit 108 variably sets the reference value Fref based on the determination result of the gas turbine state determination unit 104. Specifically, when the gas turbine state determination unit 104 determines that the gas turbine 10 is in the post-start (normal operation state), the reference value setting unit 108 sets the first reference value Fref1 as the reference value Fref. The first reference value Fref1 is a reference value corresponding to the rated flow rate Fm2 of the second feed water SW2. The rated flow rate Fm2 is the maximum allowable flow rate of the high-pressure feed water pump 45 that supplies the second feed water SW2 to the second feed water system SS2, and the first reference value Fref1 may be set taking into account a predetermined margin with respect to the rated flow rate Fm2 (the margin may be zero, and in this case, the first reference value Fref1 may be equal to the rated flow rate Fm2).

[0037] On the other hand, when the gas turbine state determination unit 104 determines that the gas turbine 10 is before startup, the reference value setting unit 108 sets the second reference value Fref2 as the reference value Fref. The second reference value Fref2 is set lower than the first reference value Fref1, and is set based on, for example, the maximum allowable flow rate Fm of the booster pump 43 and the rated flow rate Fm1 of the first feed water SW1. The maximum allowable flow rate Fm may be specified taking into account a predetermined margin with respect to the rated flow rate corresponding to the entire booster pump 43 including the high-pressure feed water pump 45 and the medium-pressure feed water pump 46 (the margin may be zero, and in this case, the maximum allowable flow rate Fm may be equal to the rated flow rate of the booster pump 43). The rated flow rate Fm1 is the maximum allowable flow rate of the medium-pressure feed water pump 46 that supplies the first feed water SW1 to the first feed water system SS1. More specifically, the second reference value Fref2 is calculated by the following formula by subtracting the product of the coefficient α and the rated flow rate Fm1 from the maximum allowable flow rate Fm. Fref2 = Fm - Fm1×α Here, the coefficient α is a value greater than 1.5, for example, "2".

[0038] Here, FIG. 4 is an explanatory diagram for showing a determination example by the condition determination unit 106 in FIG. 3. In FIG. 4, the first flow rate F1 by the medium-pressure feed water pump 46 is shown on the horizontal axis, and the second flow rate F2 by the high-pressure feed water pump 45 is shown on the vertical axis. Further, in FIG. 4, a reference line L1 corresponding to the rated flow rate Fm1 (maximum allowable flow rate) of the first feed water SW discharged from the medium-pressure feed water pump 46, a reference line L1' corresponding to twice the rated flow rate Fm1 of the first feed water SW (= 2Fm1), a reference line L2 corresponding to the rated flow rate Fm2 (maximum allowable flow rate) of the second feed water SW2 discharged from the high-pressure feed water pump 45, and a reference line L3 corresponding to the maximum allowable flow rate of the entire booster pump 43 (the sum of the maximum allowable flow rate of the high-pressure feed water pump 45 and the maximum allowable flow rate of the medium-pressure feed water pump 46) are respectively shown.

[0039] Here, in FIG. 4, several operating points A to D specified by the first flow rate F1 and the second flow rate F2 are shown. At the operating point A, the flow rates F1 and F2 are respectively equal to or less than the rated flow rates Fm1 and Fm2, and both the high-pressure feed water pump 45 and the medium-pressure feed water pump 46 are in a normal operating point without an over-flow state. Therefore, when the gas turbine 10 has been started, since the second flow rate F2 becomes equal to or less than the first reference value Fref1 set as the reference value Fref, the stop condition is not satisfied. On the other hand, when the gas turbine 10 has not been started, since the second flow rate F2 exceeds the second reference value Fref2 set as the reference value Fref, the stop condition is satisfied. (In this case, since the second flow rate F2 is equal to or less than the first reference value Fref1, actually it is not in an over-flow state, but for the purpose of making the stop condition satisfied at the operating point B described below, it is determined that the stop condition is satisfied in terms of control.)

[0040] At the operating point B, since the second flow rate F2 does not exceed the rated flow rate Fm2, the high-pressure feed water pump 45 is not in an over-flow state. However, since the first flow rate F1 exceeds the rated flow rate Fm1, an over-flow occurs in the medium-pressure feed water pump 46. According to the verification by the present inventor, it has been found that before the start-up of the gas turbine 10, even if there is no over-flow in the high-pressure feed water pump 45, an over-flow may occur in the medium-pressure feed water pump 46. Therefore, when the gas turbine 10 is before start-up, by setting a second reference value Fref2 lower than the first reference value Fref1 as the reference value Fref, it is possible to determine that the stop condition is satisfied in the case of the operating point B.

[0041] In addition, as shown by the operating point C, even though the flow rate F2 of the second feed water SW2 is equal to or less than the rated flow rate Fm2 and there is no over-flow in the high-pressure feed water pump 45, an over-flow occurs in the medium-pressure feed water pump 46 because the flow rate F1 of the first feed water SW1 exceeds the rated flow rate Fm1. Also, as shown by the operating point D, it is assumed that a case where the flow rate F1 of the first feed water SW1 exceeds the reference line L1´ even though the overall maximum allowable flow rate is exceeded does not occur, so it does not pose a problem.

[0042] Further, the condition determination unit 106 may determine that the stop condition is satisfied on the condition that the state where the flow rate F2 exceeds the reference value Fref continues for a predetermined time T or more. FIGS. 5A and 5B are diagrams showing an example of determination in the condition determination unit 106 of FIG. 3.

[0043] In FIG. 5A, at time t1, the flow rate F2 exceeds the reference value Fref, and at time t2 before time t3 when the predetermined time T has elapsed, the flow rate F2 becomes equal to or less than the reference value Fref. In this case, since the time during which the flow rate F2 continuously exceeds the reference value Fref is less than the predetermined time T, the condition determination unit 106 determines that the stop condition is not satisfied. On the other hand, in FIG. 5B, at time t1, the flow rate F2 exceeds the reference value Fref, and the state continues until time t3 when the predetermined time T has elapsed. In this case, since the time during which the state where the flow rate F2 exceeds the reference value Fref continues is equal to or more than the predetermined time T, the condition determination unit 106 determines that the stop condition is satisfied.

[0044] In this way, the condition determination unit 106 performs a validity determination on the condition that the state where the flow rate F2 exceeds the reference value Fref continues for a predetermined time T or more. As shown in FIG. 5A, it is possible to effectively prevent the control state from becoming unstable, such as the pressure boosting pump 43 being stopped due to the flow rate F2 of the second water supply SW2 temporarily exceeding the reference value Fref only for a relatively short time due to the influence of noise or the like.

[0045] Further, the condition determination unit 106 may perform a determination on the establishment of the stop condition on the condition that the state where the flow rate exceeds the third reference value Fref3, which is smaller than the reference value Fref, continues for a predetermined time T or more after the flow rate F2 exceeds the reference value Fref. The third reference value Fref3 is set to be lower than the reference value Fref by ΔFref (>0). FIGS. 6A and 5B are diagrams showing other determination examples in the condition determination unit 106 of FIG. 3.

[0046] In FIG. 6A, at time t1, the flow rate F2 exceeds the reference value Fref, and at time t2 before time t3 when the predetermined time T has elapsed, the flow rate F2 is equal to or less than the third reference value Fref3. In this case, since the time during which the state where the flow rate F2 exceeds the third reference value Fref3 continues after the flow rate F2 exceeds the reference value Fref is less than the predetermined time T, the condition determination unit 106 determines that the stop condition is not satisfied. On the other hand, in FIG. 6B, at time t1, the flow rate F2 exceeds the reference value Fref, and thereafter, the state where the flow rate exceeds the third reference value Fref3 continues for a predetermined time T or more. In this case, since the state where the flow rate F2 exceeds the third reference value Fref3 continues for a predetermined period T or more after the flow rate F2 exceeds the reference value Fref, the condition determination unit 106 determines that the stop condition is satisfied.

[0047] In this way, after the flow rate F2 exceeds the reference value Fref, the condition determination unit 106 performs an establishment determination on the condition that the state where the flow rate F2 exceeds the third reference value Fref3 set lower than the reference value Fref continues for a predetermined time T or more (that is, by giving the reference value Fref hysteresis characteristics). As shown in FIG. 6A, it is possible to effectively prevent the control state from becoming unstable, such as the boost pump 43 being stopped from being controlled when the flow rate F2 of the second water supply SW2 temporarily exceeds the reference value Fref for a relatively short time due to the influence of noise or the like.

[0048] The boost pump control unit 110 is a configuration for controlling the boost pump 43. When the stop condition is satisfied in the condition determination unit 106, the boost pump control unit 110 performs interlock control to stop the boost pump 43.

[0049] As described above, according to the above embodiment, when the flow rate F2 of the second water supply SW2 on the high-pressure side exceeds the reference value Fref, the boost pump 43 is stopped, so that it is possible to preferably prevent the boost pump 43 from having an excessive flow rate. The reference value Fref compared with the flow rate F2 of the second water supply SW2 is variably set before and after the start of the gas turbine 10. In particular, the second reference value Fref2 corresponding to before the start of the gas turbine 10 is set lower than the first reference value Fref1 corresponding to after the start of the gas turbine 10. Before the start of the gas turbine 10, even if the flow rate F2 of the second water supply SW2 to the second water supply system SS2 on the high-pressure side does not exceed the rated flow rate value of the boost pump 43, the flow rate F1 of the first water supply SW1 corresponding to the first water supply system SS1 on the low-pressure side is likely to exceed the rated flow rate value of the boost pump 43. Therefore, by setting the reference value Fref compared with the flow rate F2 of the second water supply SW2 to the second reference value Fref2 lower than the first reference value Fref1, it is possible to preferably prevent the boost pump 43 from having an excessive flow rate with respect to the first water supply system SS1 without requiring the detection of the flow rate of the first water supply system SS1.

[0050] In addition, within the scope not departing from the gist of the present disclosure, it is possible to appropriately replace the components in the above-described embodiments with well-known components, and the above-described embodiments may also be combined as appropriate.

[0051] The content described in each of the above embodiments is understood as follows, for example.

[0052] (1) A plant control device according to one aspect a boiler for generating steam using the exhaust heat of a gas turbine, a booster pump for generating first feed water and second feed water having a higher pressure than the first feed water by boosting the condensate generated from the steam, a first feed water system for supplying the first feed water to a first steam generation drum, a second feed water system for supplying the second feed water to a second steam generation drum, a plant control device for controlling a plant comprising a second feed water flow rate acquisition unit for acquiring the flow rate of the second feed water, a booster pump control unit for controlling the booster pump, comprising the booster pump control unit stops the booster pump on the condition that the flow rate acquired by the second feed water flow rate acquisition unit exceeds a reference value, the reference value is set to a first reference value corresponding to the rated flow rate of the second feed water after startup of the gas turbine, and is set to a second reference value lower than the first reference value before startup of the gas turbine.

[0053] According to the aspect (1) above, when the flow rate of the second feed water on the high-pressure side exceeds the reference value, the booster pump is stopped, so that it is possible to preferably prevent the booster pump from having an excessive flow rate. The reference value compared with the flow rate of the second feed water is variably set before and after the start of the gas turbine. In particular, the second reference value corresponding to before the start of the gas turbine is set lower than the first reference value corresponding to after the start of the gas turbine. Before the start of the gas turbine, even if the flow rate of the second feed water to the second feed water system on the high-pressure side does not exceed the rated flow rate value of the booster pump, the flow rate of the first feed water corresponding to the first feed water system on the low-pressure side is likely to exceed the rated flow rate value of the booster pump. Therefore, by setting the reference value compared with the flow rate of the second feed water to the second reference value lower than the first reference value, it is possible to preferably prevent the booster pump from having an excessive flow rate with respect to the first feed water system without requiring the detection of the flow rate of the first feed water system.

[0054] (2) In another aspect, in the aspect (1) above, Before the start of the gas turbine, the booster pump control unit stops the booster pump on the condition that the state where the flow rate acquired by the second feed water flow rate acquisition unit exceeds the second reference value continues for a predetermined time or more.

[0055] According to the aspect (2) above, when the booster pump is stopped and controlled before the start of the gas turbine, it is a condition that the state where the flow rate of the second feed water on the high-pressure side exceeds the second reference value continues for a predetermined period. Thereby, it is possible to effectively prevent the control state from becoming unstable, such as the booster pump being stopped and controlled because the flow rate of the second feed water instantaneously exceeds the second reference value due to the influence of noise or the like.

[0056] (3) In another aspect, in the aspect (1) above, Before the start of the gas turbine, the booster pump control unit stops the booster pump on the condition that after the flow rate acquired by the second feed water flow rate acquisition unit exceeds the second reference value, the state where the flow rate does not exceed a third reference value smaller than the second reference value continues for a predetermined time or more.

[0057] According to the aspect (3) above, when the pressure boosting pump is stopped and controlled before the start-up of the gas turbine, it is a condition that after the flow rate of the second feed water on the high-pressure side exceeds the second reference value, a state where the flow rate does not exceed a third reference value smaller than the second reference value continues for a predetermined period. Thereby, it is possible to effectively prevent the control state from becoming unstable, such as the pressure boosting pump being stopped and controlled just because the flow rate of the second feed water instantaneously exceeds the second reference value due to the influence of noise or the like.

[0058] (4) In another aspect, in any one of the aspects (1) to (3) above, The second reference value is set based on the maximum allowable flow rate of the pressure boosting pump and the rated flow rate of the first feed water.

[0059] According to the aspect (4) above, by setting the second reference value based on the maximum allowable flow rate of the pressure boosting pump and the rated flow rate of the first feed water, it is possible to preferably determine a situation where the flow rate of the first feed water becomes an over-flow rate by the pressure boosting pump before the start-up of the gas turbine.

[0060] (5) In another aspect, in the aspect (4) above, The second reference value is calculated by subtracting the product of the rated flow rate of the first feed water and a coefficient from the maximum allowable flow rate.

[0061] According to the aspect (5) above, by using the second reference value calculated by subtracting the product of the rated flow rate of the first feed water and a coefficient from the maximum allowable flow rate, it is possible to preferably determine a situation where the flow rate of the first feed water becomes an over-flow rate by the pressure boosting pump before the start-up of the gas turbine.

[0062] (6) In another aspect, in any one of the aspects (1) to (5) above, The pressure boosting pump has a condensate inlet for introducing the condensate, a second feed water discharge port for discharging the second feed water, a second feed water line extending from the condensate inlet to the second feed water discharge port, A first water supply line that branches from the middle of the second water supply line and leads to a first water supply outlet for discharging the first water supply, is provided.

[0063] According to the aspect of (6) above, the first water supply line and the second water supply line provided in the booster pump are configured such that the first water supply line branches from the second water supply line. By stopping the booster pump when the second flow rate exceeds the reference value in the booster pump configured in this way, it is possible to preferably prevent the booster pump from having an excessive flow rate.

[0064] (7) A plant control method according to one aspect is a boiler for generating steam using the exhaust heat of a gas turbine, a booster pump for generating a first water supply and a second water supply having a higher pressure than the first water supply by boosting the condensate generated from the steam, a first water supply system for supplying the first water supply to a first steam generation drum, a second water supply system for supplying the second water supply to a second steam generation drum, a plant control method for controlling a plant comprising: a step of detecting the flow rate of the second water supply; a step of stopping the booster pump on the condition that the flow rate exceeds a reference value; is provided, the reference value is set to a first reference value corresponding to the rated flow rate of the second water supply after the gas turbine is started, and is set to a second reference value lower than the first reference value before the gas turbine is started.

[0065] According to the aspect of (7) above, when the flow rate of the second feed water on the high-pressure side exceeds the reference value, the booster pump is stopped, so that it is possible to preferably prevent the booster pump from having an excessive flow rate. The reference value compared with the flow rate of the second feed water is variably set before and after the start-up of the gas turbine. In particular, the second reference value corresponding to before the start-up of the gas turbine is set lower than the first reference value corresponding to after the start-up of the gas turbine. Before the start-up of the gas turbine, even if the flow rate of the second feed water to the second feed water system on the high-pressure side does not exceed the rated flow rate value of the booster pump, the flow rate of the first feed water corresponding to the first feed water system on the low-pressure side is likely to exceed the rated flow rate value of the booster pump. Therefore, by setting the reference value compared with the flow rate of the second feed water to the second reference value lower than the first reference value, it is possible to preferably prevent the booster pump from having an excessive flow rate with respect to the first feed water system without requiring the detection of the flow rate of the first feed water system.

[0066] (8) A plant control program according to one aspect is a boiler for generating steam using the exhaust heat of a gas turbine, a booster pump for boosting the condensate generated from the steam to generate first feed water and second feed water having a higher pressure than the first feed water, a first feed water system for supplying the first feed water to a first steam generation drum, a second feed water system for supplying the second feed water to a second steam generation drum, a plant control program for controlling a plant comprising a computer device, a step of acquiring the flow rate of the second feed water, a step of stopping the booster pump on condition that the flow rate exceeds a reference value, is executable, the reference value is set to a first reference value corresponding to the rated flow rate of the second feed water after the start-up of the gas turbine, and is set to a second reference value lower than the first reference value before the start-up of the gas turbine.

[0067] According to the aspect of (8) above, when the flow rate of the second feed water on the high-pressure side exceeds the reference value, the booster pump is stopped, so that it is possible to preferably prevent the booster pump from having an excessive flow rate. The reference value compared with the flow rate of the second feed water is variably set before and after the start-up of the gas turbine. In particular, the second reference value corresponding to before the start-up of the gas turbine is set lower than the first reference value corresponding to after the start-up of the gas turbine. Before the start-up of the gas turbine, even if the flow rate of the second feed water to the second feed water system on the high-pressure side does not exceed the rated flow rate value of the booster pump, the flow rate of the first feed water corresponding to the first feed water system on the low-pressure side is likely to exceed the rated flow rate value of the booster pump. Therefore, by setting the reference value compared with the flow rate of the second feed water to the second reference value lower than the first reference value, it is possible to preferably prevent the booster pump from having an excessive flow rate with respect to the first feed water system without requiring the detection of the flow rate of the first feed water system.

Explanation of Signs

[0068] 1 Combined cycle plant 10 Gas turbine 11 Compressor 15 Turbine 19 Gas turbine rotor 20 Heat recovery boiler 21 Low-pressure economizer 22 Low-pressure evaporator 23 High-pressure primary economizer 24 Medium-pressure economizer 25 Medium-pressure evaporator 26 Low-pressure superheater 27 High-pressure secondary economizer 28 Medium-pressure superheater 29 High-pressure evaporator 30 High-pressure primary superheater 31 Primary reheater 32 Secondary reheater 33 High-pressure secondary superheater 34 Chimney 39 Makeup water supply pump 40 Condenser 41 Makeup water supply line 42 Makeup water tank 43 Booster pump 44 Low-pressure drum 45 High-pressure feed water pump 46 Medium-pressure feed water pump 47 High-pressure drum 48 Medium-pressure drum 49a First desuperheater 49b Second desuperheater 50 Second feed water line 51 Flow detector 52 BFP outlet motorized valve 53 ECO inlet motorized valve 54 ECO inlet control valve 55 Minimum flow line 56 Injection line 57 Heat exchange medium supply line 60 Steam turbine 61 Steam turbine rotor 62 Condensate supply line 63 Low-pressure feed water pump 64 Desuperheater 100 Control device 102 Second feed water flow acquisition unit 104 Gas turbine state determination unit 106 Condition determination unit 108 Reference value setting unit 110 Boost pump control unit SW1 First feed water SW2 Second feed water SS1 First feed water system SS2 Second feed water system

Claims

1. A boiler for generating steam using the exhaust heat of a gas turbine, A booster pump for generating first feed water and second feed water at a higher pressure than the first feed water by boosting the condensate generated from the steam, A first feed water system for supplying the first feed water to a first steam generation drum, A second feed water system for supplying the second feed water to a second steam generation drum, A plant control device for controlling a plant comprising: A second feed water flow rate acquisition unit for acquiring the flow rate of the second feed water, A booster pump control unit for controlling the booster pump, Comprising: The booster pump control unit stops the booster pump on the condition that the flow rate acquired by the second feed water flow rate acquisition unit exceeds a reference value, The reference value is set to a first reference value corresponding to the rated flow rate of the second feed water after the gas turbine is started, and is set to a second reference value lower than the first reference value before the gas turbine is started. A plant control device.

2. Before starting the gas turbine, the booster pump control unit stops the booster pump on the condition that the state where the flow rate acquired by the second feed water flow rate acquisition unit exceeds the second reference value continues for a predetermined time or more. The plant control device according to claim 1.

3. Before starting the gas turbine, after the flow rate acquired by the second feed water flow rate acquisition unit exceeds the second reference value, the booster pump control unit stops the booster pump on the condition that the state where the flow rate does not exceed a third reference value smaller than the second reference value continues for a predetermined time or more. The plant control device according to claim 1.

4. The second reference value is set based on the maximum allowable flow rate of the booster pump and the rated flow rate of the first feed water. The plant control device according to any one of claims 1 to 3.

5. The second reference value is calculated by subtracting the product of a coefficient and the rated flow rate of the first feed water from the maximum allowable flow rate. The plant control device according to claim 4.

6. The booster pump A condensate inlet for introducing the condensate, A second feed water discharge port for discharging the second feed water, A second feed water line extending from the condensate inlet to the second feed water discharge port, A first feed water line branching from the middle of the second feed water line and extending to a first feed water discharge port for discharging the first feed water, The plant control device according to any one of claims 1 to 3, comprising

7. A boiler for generating steam using the exhaust heat of a gas turbine, A booster pump for generating first feed water and second feed water having a higher pressure than the first feed water by boosting the condensate generated from the steam, A first feed water system for supplying the first feed water to a first steam generation drum, A second feed water system for supplying the second feed water to a second steam generation drum, A plant control method for controlling a plant comprising: A step of obtaining the flow rate of the second feed water; A step of stopping the booster pump on condition that the flow rate exceeds a reference value; Comprising The reference value is set to a first reference value corresponding to the rated flow rate of the second feed water after startup of the gas turbine, and is set to a second reference value lower than the first reference value before startup of the gas turbine. A plant control method.

8. A boiler for generating steam using the exhaust heat of a gas turbine, A booster pump for generating first feed water and second feed water having a higher pressure than the first feed water by boosting the condensate generated from the steam, A first feed water system for supplying the first feed water to a first steam generation drum, A second feed water system for supplying the second feed water to a second steam generation drum, A plant control program for controlling a plant comprising: On a computer device, A step of obtaining the flow rate of the second feed water; A step of stopping the booster pump on condition that the flow rate exceeds a reference value; Is executable, The reference value is set to a first reference value corresponding to the rated flow rate of the second feed water after startup of the gas turbine, and is set to a second reference value lower than the first reference value before startup of the gas turbine. A plant control program.

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