Valve controller and valve control method

Abstract

To provide a valve controller and valve control method capable of stabilizing a water level of deaerated water in a deaerator even in a case where operating situations of plural boilers vary.SOLUTION: A valve controller includes a deaerator, a slave valve, a master valve, plural boilers, a level measurement unit that measures a water level in the deaerator, a flow measurement unit that measures a flow of deaerated water to be supplied from the deaerator to the plural boilers, a memory unit that stores an aperture function, and a control unit. The control unit performs first processing of controlling the aperture of the slave valve so that the water level measured by the level measurement unit approaches a predetermined target value, and second processing of controlling the aperture of the master valve on the basis of the flow measured by the flow measurement unit so that the aperture comes to an aperture obtained using the aperture function which is stored in the memory unit.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a valve control device and a valve control method. [Background technology]

[0002] Patent Document 1 discloses a boiler feedwater device used in a steam turbine power generation system. The device includes a deaerator and multiple boilers. The deaerator is configured to remove gases such as oxygen and carbon dioxide present in the condensate supplied from the condenser. The deaerator deaerates the deaerator and supplies the deaerated water to each boiler to become steam, which is used to generate power in the power generation turbine. The number of operating boilers is determined based on the required amounts of power generation and steam supply of the power generation system, and the operation of the operating boilers is stopped and the operation of the stopped boilers is started.

[0003] The amount of condensate supplied from the condenser to the deaerator varies depending on the load fluctuation of the power generation system. Also, the amount of deaerated water supplied from the deaerator to the boiler varies depending on the number of boilers in operation. These fluctuations cause the water level of the deaerator to fluctuate (fluctuate up and down). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-291906 A Summary of the Invention [Problem to be solved by the invention]

[0005] Before and after a change in the number of boilers in operation, the amount of deaerated water fed from the deaerator to the boiler fluctuates greatly. In this case, if there is only one valve between the condenser and the deaerator, the range ability of the valve is exceeded. For this reason, two valves of different sizes (a parent valve and a child valve) are generally provided between the condenser and the deaerator. Then, when the amount of deaerated water fed from the deaerator to the boiler is small, the child valve controls the amount of condensate fed from the condenser to the deaerator. On the other hand, when the number of boilers in operation increases and the amount of deaerated water fed from the deaerator to the boiler fluctuates greatly, the parent valve controls the amount of condensate fed from the condenser to the deaerator.

[0006] However, when the control target switches from the child valve to the parent valve, the water level in the deaerator fluctuates significantly. This can lead to unstable control of the water level in the deaerator. In addition, when the peaks of the amount of deaerated water supplied to multiple boilers overlap, the valve operation cannot keep up with the significant drop in the water level in the deaerator, and pressure fluctuations can occur in the deaerator. As a result, the lifespan of the deaerator and its peripheral equipment can be affected, and maintenance work and costs can increase.

[0007] Therefore, the present disclosure describes a valve control device and a valve control method that can stabilize the water level of deaerated water in a deaerator even when the operating conditions of multiple boilers change. [Means for solving the problem]

[0008] One example of a valve control device includes a deaerator configured to remove gas contained in water supplied from a water supply device, a child valve provided on a first pipe extending between the water supply device and the deaerator, a parent valve provided on a second pipe extending parallel to the first pipe between the water supply device and the deaerator and configured to adjust a flow rate greater than that of the child valve, a plurality of boilers to which deaerated water deaerated in the deaerator is supplied, a level measuring unit configured to measure the water level in the deaerator, a flow measuring unit configured to measure the flow rate of deaerated water supplied from the deaerator to the plurality of boilers, a memory unit configured to store an opening function indicating the relationship between the flow rate of deaerated water flowing to the plurality of boilers and the opening of the parent valve that is preset in accordance with the flow rate, and a control unit. The control unit is configured to execute a first process of controlling the opening of the child valve so that the water level measured in the level measuring unit approaches a predetermined target value, and a second process of controlling the opening of the parent valve so that the opening is determined from the opening function stored in the memory unit based on the flow rate measured in the flow measuring unit. Effect of the Invention

[0009] According to the valve control device and valve control method disclosed herein, it is possible to stabilize the water level of deaerated water in the deaerator even when the operating conditions of multiple boilers change. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a steam turbine power generation system. [Diagram 2] FIG. 2 is a schematic diagram mainly showing the hardware configuration of the controller. [Diagram 3] Figure 3(a) is a graph showing an example of the relationship between the total flow rate of degassed water to the boiler and the opening degree of the parent valve, and Figure 3(b) is a table showing an example of the relationship between the total flow rate of degassed water to the boiler and the opening degree of the parent valve. [Figure 4] Figure 4(a) is a graph showing an example of the relationship between the total flow rate of degassed water to the boiler and the opening degree of the parent valve, and Figure 4(b) is a table showing an example of the relationship between the total flow rate of degassed water to the boiler and the opening degree of the parent valve. [Diagram 5] FIG. 5 is a block diagram showing an example of a valve control device. [Figure 6] Figure 6 shows graphs when two boilers are operating in a steam turbine power generation system, where Figure 6(a) is a graph showing an example of the change in water level over time in a deaerator, Figure 6(b) is a graph showing an example of the change in pressure over time in the deaerator, Figure 6(c) is a graph showing an example of the change in the flow rate of deaerator water to each boiler, Figure 6(d) is a graph showing an example of the change in the opening degree of the parent valve and child valve over time, and Figure 6(e) is a graph showing an example of the change in the steam flow rate heading toward the deaerator over time. [Figure 7] FIG. 7 is a graph showing an example of a change in water level over time in a deaerator in a steam turbine power generation system in which three boilers are in operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the following description, the same elements or elements having the same functions are designated by the same reference numerals, and duplicated descriptions will be omitted. In this specification, when referring to the top, bottom, right, and left of the figure, the directions of the reference numerals in the figure are used as the reference.

[0012] [Configuration of steam turbine power generation system] As illustrated in FIG. 1, a steam turbine power generation system 1 (valve control device) includes a power generation facility 2 and a controller Ctr (control unit).

[0013] The power generation equipment 2 includes a steam turbine 10, a generator 11, a condenser 12 (water supply device), a deaerator 13, multiple boilers 14, a high-pressure steam reservoir 15, a low-pressure steam reservoir 16, pumps P1 to P4, a child valve V1, a parent valve V2, a steam valve V3, a level sensor SE1, a pressure sensor SE2, flow sensors SE3 to SE6, and piping D1 to D15.

[0014] The steam turbine 10 is connected to a generator 11 via a shaft 10a. The steam turbine 10 is configured to be rotated by steam generated in a boiler 14, and to rotate the generator 11 via the shaft 10a. In this way, power is generated in the generator 11. The steam used to rotate the steam turbine 10 is supplied to a condenser 12 via a pipe D1.

[0015] The condenser 12 is configured to cool the steam discharged from the steam turbine 10 and condense it into water. The water condensed in the condenser 12 (hereinafter also referred to as "condensed water") is supplied to the deaerator 13 through pipes D2 to D4. The upstream end of the pipe D2 is connected to the condenser 12. The downstream end of the pipe D2 is connected to the upstream ends of the pipes D3 and D4. The downstream ends of the pipes D3 and D4 are each connected to the deaerator 13. Therefore, the pipes D2 and D3 (first pipes) extend between the condenser 12 and the deaerator 13. On the other hand, the pipe D4 (second pipe) extends so as to branch off from the pipes D2 and D3.

[0016] A pump P1 is provided in the pipe D2. The pump P1 is configured to operate based on a control signal from the controller Ctr and to send the condensate in the condenser 12 to the deaerator 13. A child valve V1 is provided in the pipe D3. A parent valve V2 is provided in the pipe D4. Therefore, the pipe D4 extends so as to bypass the child valve V1.

[0017] The child valve V1 operates based on a control signal from the controller Ctr and is configured to open and close the pipe D3 before and after the child valve V1. The parent valve V2 operates based on a control signal from the controller Ctr and is configured to open and close the pipe D4 before and after the parent valve V2. The parent valve V2 is configured to be able to adjust a flow rate greater than that of the child valve V1. In other words, the parent valve V2 is configured so that the flow rate when the parent valve V2 is fully open is greater than the flow rate when the child valve V1 is fully open.

[0018] The deaerator 13 is configured to remove gas (e.g., oxygen, carbon dioxide, and the like dissolved in the condensate) contained in the condensate supplied from the condenser 12. The deaerator 13 heats the condensate supplied from the condenser 12 with heating steam to turn it into saturated water, and deaerates the dissolved gas from the condensate.

[0019] The deaerator 13 is provided with a level sensor SE1 (level measurement unit) configured to measure the water level in the deaerator 13. Data measured by the level sensor SE1 is transmitted to the controller Ctr.

[0020] The deaerator 13 is provided with a pressure sensor SE2 (pressure measurement unit) configured to measure the pressure inside the deaerator 13. Data measured by the pressure sensor SE2 is transmitted to the controller Ctr.

[0021] The water deaerated in the deaerator 13 (hereinafter, also referred to as "deaerated water") is supplied to a plurality of boilers 14 (three boilers 14a-14c in the example of FIG. 1) through pipes D5-D8. The upstream end of pipe D5 is connected to the deaerator 13. Pipes D6-D8 branch off from pipe D5. The upstream end of pipe D6 is connected to the middle of pipe D5. The downstream end of pipe D6 is connected to boiler 14a. The upstream end of pipe D7 is connected to the downstream side of the pipe D5 from which pipe D6 branches off. The downstream end of pipe D7 is connected to boiler 14b. The upstream end of pipe D8 is connected to the downstream end of pipe D5. The downstream end of pipe D8 is connected to boiler 14c.

[0022] The pipe D6 is provided with a pump P2 and a flow rate sensor SE3 (flow rate measurement unit) in this order from the upstream side. The pump P2 is configured to operate based on a control signal from the controller Ctr and to send the deaerated water in the deaerator 13 to the boiler 14a. The flow rate sensor SE3 is configured to measure the flow rate of the deaerated water flowing through the pipe D6. Data measured by the flow rate sensor SE3 is transmitted to the controller Ctr.

[0023] The pipe D7 is provided with a pump P3 and a flow rate sensor SE4 (flow rate measurement unit) in this order from the upstream side. The pump P3 is configured to operate based on a control signal from the controller Ctr and to send the deaerated water in the deaerator 13 to the boiler 14b. The flow rate sensor SE4 is configured to measure the flow rate of the deaerated water flowing through the pipe D7. Data measured by the flow rate sensor SE4 is transmitted to the controller Ctr.

[0024] The pipe D8 is provided with a pump P4 and a flow rate sensor SE5 (flow rate measurement unit) in this order from the upstream side. The pump P4 is configured to operate based on a control signal from the controller Ctr and to send the deaerated water in the deaerator 13 to the boiler 14c. The flow rate sensor SE5 is configured to measure the flow rate of the deaerated water flowing through the pipe D8. The data measured by the flow rate sensor SE5 is transmitted to the controller Ctr.

[0025] Each of the boilers 14 is configured to generate high-temperature, high-pressure steam by, for example, heating deaerated water with heat from fuel combustion. The steam (hereinafter also referred to as "high-pressure steam") generated in the boilers 14 is supplied to the high-pressure steam reservoir 15 through pipes D9 to D12. The upstream end of pipe D9 is connected to boiler 14a. The upstream end of pipe D10 is connected to boiler 14b. The upstream end of pipe D11 is connected to boiler 14c. The downstream ends of pipes D9 to D11 are joined together and connected to the upstream end of pipe D12. The downstream end of pipe D12 is connected to the high-pressure steam reservoir 15.

[0026] The high-pressure steam reservoir 15 is configured to temporarily store high-pressure steam generated in the multiple boilers 14. The high-pressure steam reservoir 15 supplies a part or all of the stored high-pressure steam to the steam turbine 10 through a pipe D13. The high-pressure steam that is not supplied from the high-pressure steam reservoir 15 to the steam turbine 10 is supplied to the low-pressure steam reservoir 16 through a pipe D14 branching off from the pipe D13.

[0027] An upstream end of the pipe D13 is connected to a high-pressure steam reservoir 15. A downstream end of the pipe D13 is connected to the steam turbine 10. An upstream end of the pipe D14 is connected to the middle of the pipe D13. A downstream end of the pipe D14 is connected to a low-pressure steam reservoir 16. The pipe D14 is provided with a pressure reducing device (not shown).

[0028] The low-pressure steam reservoir 16 is configured to temporarily store steam (hereinafter also referred to as "low-pressure steam") that has been depressurized in a pressure reducing device from the high-pressure steam reservoir 15. The low-pressure steam reservoir 16 supplies the stored low-pressure steam to the deaerator 13 through a pipe D15. The low-pressure steam is used in the deaerator 13 as heating steam for heating the condensate.

[0029] The pipe D15 is provided with a flow sensor SE6 (steam flow rate measuring unit) and a steam valve V3 in this order from the upstream side. The flow sensor SE6 is configured to measure the flow rate of low-pressure steam supplied to the deaerator 13. Data measured by the flow sensor SE6 is transmitted to the controller Ctr. The steam valve V3 is configured to operate based on a control signal from the controller Ctr and to open and close the pipe D15 before and after the steam valve V3.

[0030] As illustrated in FIG. 2, the controller Ctr is configured to process data received from the level sensor SE1, the pressure sensor SE2, and the flow sensors SE3 to SE6, and to control the opening of the child valve V1, the parent valve V2, and the steam valve V3, and the operation of the pumps P1 to P4.

[0031] The hardware of the controller Ctr is composed of, for example, one or more control computers. As a hardware configuration, the controller Ctr includes a processor C1 (arithmetic unit), a memory C2 (storage unit), an input port C3 (input unit), and an output port C4 (output unit), as exemplified in Fig. 2. The controller Ctr may be composed of electric circuit elements (circuitry).

[0032] The processor C1 cooperates with the memory C2 to execute a program and inputs and outputs signals via the input port C3 and the output port C4 to configure each of the functional modules described below. That is, the processor C1 is configured to generate output signals for driving the valves V1-V3 and the pumps P1-P4 based on input signals from the sensors SE1-SE6.

[0033] The memory C2 is configured to store programs, input signals, output signals, etc. The memory C2 is configured to store an opening function indicating the relationship between the flow rate of the deaerated water flowing through the multiple boilers 14 and the opening of the master valve V2 that is set in advance according to the flow rate. The memory C2 may store one such opening function, or may store a plurality of such opening functions according to the number of the multiple boilers 14 in operation.

[0034] The opening function may be obtained in advance by an experiment. For example, the experiment may determine the opening of the master valve V2 at which the water level in the deaerator 13 is stabilized near a predetermined target value SV1 (see FIG. 5) for the sum of the flow rates (total flow rate) measured by the flow rate sensors SE3 to SE5 when two or more of the plurality of boilers 14 are in operation.

[0035] Figure 3(a) shows an example of the opening function F1 when two of the multiple boilers 14 are operating. The opening function F1 in Figure 3(a) is a line graph in which the data in the table shown in Figure 3(b) are plotted with the horizontal axis representing the total flow rate into the multiple boilers 14 and the vertical axis representing the opening of the master valve V2, and adjacent data are connected by a straight line. The opening function F1 exemplified in Figure 3(a) does not have a section that slopes downward to the right, so it can be said to be a monotonically non-decreasing broken-line function.

[0036] FIG. 4(a) shows an example of the opening function F2 when three of the multiple boilers 14 are operating. The opening function F2 in FIG. 4(a) is a line graph in which the data in the table shown in FIG. 4(b) is plotted with the horizontal axis representing the total flow rate to the multiple boilers 14 and the vertical axis representing the opening of the parent valve V2, and adjacent data are connected by a straight line. The opening function F2 exemplified in FIG. 4(a) does not have a section that slopes downward to the right, so it can be said to be a monotonically non-decreasing broken line function. As in the example shown in FIG. 4(a), all or most of the opening function F2 may be in a region where the total flow rate to the multiple boilers 14 is higher and the opening of the parent valve V2 is larger than the opening function F1.

[0037] Although not shown, the opening functions F1 and F2 may be, for example, a monotonically increasing linear function or a monotonically non-decreasing curved function.

[0038] The input port C3 is configured to transmit input signals from the sensors SE1 to SE6 to the processor C1. The output port C4 is configured to transmit output signals generated by the processor C1 to the valves V1 to V3 and the pumps P1 to P4.

[0039] As illustrated in Fig. 5, the controller Ctr includes, as functional modules, a calculation unit M1, a PID control unit M2, a function unit M3, a correction unit M4, a calculation unit M5, and a PID control unit M6. These functional modules are merely a division of the functions of the controller Ctr into a plurality of modules for convenience, and do not mean that the hardware constituting the controller Ctr is divided into such modules. Each functional module is not limited to being realized by the execution of a program, and may be realized by a dedicated electric circuit (e.g., a logic circuit) or an integrated circuit (ASIC: Application Specific Integrated Circuit) that integrates the same.

[0040] The calculation unit M1 is configured to calculate the deviation (SV1-PV1) between a measured value PV1 of the water level in the deaerator 13 measured by the level sensor SE1 and a preset target value SV1 of the water level in the deaerator 13. The calculation unit M1 is configured to output the calculated deviation to the PID control unit M2.

[0041] The PID control unit M2 is configured to perform PID calculations on the output from the calculation unit M1 and calculate a manipulated variable MV1 for the opening of the child valve V1. The PID control unit M2 is configured to adjust the opening of the child valve V1 based on the calculated manipulated variable MV1. As a result, the opening of the child valve V1 is adjusted so that the water level in the deaerator 13 approaches the target value SV1.

[0042] The function unit M3 is configured to select one of the opening functions F1 and F2 based on the number of operating boilers 14. For example, the function unit M3 may acquire the total flow rate of deaerated water to the boilers 14 using the flow sensors SE3 to SE5, and determine the number of operating boilers 14 based on the total flow rate. For example, the function unit M3 may determine that the number of operating pumps among the pumps P2 to P4 is the number of operating boilers 14.

[0043] When the function unit M3 determines that the number of boilers 14 in operation is one, it is not necessary to select the opening functions F1 and F2. In this case, the manipulated variable MV2 of the opening of the parent valve V2 is 0. That is, when the number of boilers 14 in operation is one, the water level in the deaerator 13 may be adjusted only by the child valve V1. When the function unit M3 determines that the number of boilers 14 in operation is two, it may select the opening function F1. When the function unit M3 determines that the number of boilers 14 in operation is three, it may select the opening function F2.

[0044] The function unit M3 is configured to calculate a manipulated variable MV2 for the opening of the master valve V2 based on the sum of the flow rates (total flow rate) measured by the flow sensors SE3 to SE5 and the selected one of the opening functions. The function unit M3 is configured to output the calculated manipulated variable MV2 to the correction unit M4.

[0045] Incidentally, the opening degree of the parent valve V2 obtained from the opening degree function may be excessive with respect to the flow rate of the deaerator water supplied to the plurality of boilers 14. In this case, as the amount of condensate water supplied to the deaerator 13 increases, the steam (low-pressure steam) supplied to the deaerator 13 is used more for heat exchange with the condensate water, and the pressure in the deaerator 13 decreases. Therefore, the steam flow rate supplied to the deaerator 13 increases, and the pressure fluctuation in the deaerator 13 may increase. On the other hand, the opening degree of the parent valve V2 obtained from the opening degree function may be excessively small with respect to the flow rate of the deaerator water supplied to the plurality of boilers 14. In this case, as the amount of condensate water supplied to the deaerator 13 decreases, the steam (low-pressure steam) supplied to the deaerator is not used much for heat exchange with the condensate water, and the pressure in the deaerator 13 increases. Therefore, the steam flow rate supplied to the deaerator 13 decreases, and the pressure fluctuation in the deaerator 13 may increase.

[0046] Therefore, the correction unit M4 is configured to correct the operation amount MV2 output from the function unit M3 based on the flow rate (flow rate of low-pressure steam) measured by the flow rate sensor SE6 to calculate a corrected operation amount MV3 indicating a corrected opening degree of the parent valve V2. For example, when the steam flow rate supplied to the deaerator 13 is larger than a predetermined threshold value (e.g., 4.5 tons / hour), the correction unit M4 may correct the opening degree of the parent valve V2 to be smaller. That is, the corrected operation amount MV3 may be calculated by subtracting a correction value α from the operation amount MV2. The correction value α may be set to a value that subtracts the operation amount MV2 by 0.5%, for example. On the other hand, when the steam flow rate supplied to the deaerator 13 is smaller than another predetermined threshold value (e.g., 2.7 tons / hour), the correction unit M4 may correct the opening degree of the parent valve V2 to be larger. That is, the corrected operation amount MV3 may be calculated by adding a correction value β to the operation amount MV2. The correction value β may be set to a value that increases the manipulated variable MV2 by 0.5%, for example.

[0047] The correction unit M4 is configured to adjust the aperture of the parent valve V2 based on the calculated corrected manipulated variable MV3. As a result, the aperture of the parent valve V2 is adjusted to an aperture calculated from an aperture function, or to a corrected aperture obtained by correcting the aperture based on the flow rate of the low-pressure steam supplied to the deaerator 13.

[0048] The calculation unit M5 is configured to calculate the deviation (SV2-PV4) between a measured value PV4 of the pressure in the degasser 13 measured by the pressure sensor SE2 and a preset target value SV2 of the pressure in the degasser 13. The calculation unit M5 is configured to output the calculated deviation to the PID control unit M6.

[0049] The PID control unit M6 is configured to perform PID calculations on the output from the calculation unit M5 and calculate a manipulated variable MV4 for the opening of the steam valve V3. The PID control unit M6 is configured to adjust the opening of the steam valve V3 based on the calculated manipulated variable MV4. As a result, the opening of the steam valve V3 is adjusted so that the pressure in the deaerator 13 approaches the target value SV2.

[0050] [Valve control method] Next, a method for controlling each of the valves V1 to V3 will be described. During operation of the steam turbine power generation system 1, the opening of the sub-valve V1 is adjusted based on a measurement value PV1 of the level sensor SE1 so that the water level in the deaerator 13 approaches a target value SV1. The opening of the steam valve V3 is adjusted based on a measurement value PV4 of the pressure sensor SE2 so that the pressure in the deaerator 13 approaches a target value SV2.

[0051] On the other hand, the aperture of the parent valve V2 is adjusted based on one aperture function selected according to the number of operating boilers 14. When the flow rate of low-pressure steam to the deaerator 13 is outside a predetermined range, the aperture of the parent valve V2 is adjusted so that the aperture obtained from the aperture function becomes a corrected aperture.

[0052] FIG. 6 shows the changes in (a) water level, (b) pressure in the deaerator 13, (c) flow rate to the boiler 14, (d) valve opening, and (e) flow rate of low-pressure steam to the deaerator 13 when two of the multiple boilers 14, 14a and 14b, are operated. As shown in FIG. 6(a), it was confirmed that the water level in the deaerator 13 fluctuated only within about ±50 mm from the target value, and that the water level could be extremely stabilized. Also, as shown in FIG. 6(b), it was confirmed that the pressure in the deaerator 13 fluctuated only within about ±40 kPa from the target value of 300 kPa, and that the pressure in the deaerator 13 could be extremely stabilized.

[0053] Furthermore, as shown in Figures 6(d) and (e), when the flow rate of low-pressure steam to the deaerator 13 increases (see the rightmost peak in Figure 6(e)), the opening of the parent valve V2 decreases stepwise (see the dashed line in Figure 6(d)), and the opening of the parent valve V2 is corrected. As a result, it was confirmed that while the flow rate of deaerated water to the boiler 14 decreases as shown in Figure 6(c), the water level in the deaerator 13 stabilizes as shown in Figure 6(a).

[0054] In addition, Fig. 7 shows the changes in the water level when three of the boilers 14, 14a to 14c, were operated. As shown in Fig. 7, even when the number of operating boilers 14 was increased to three, the water level in the deaerator 13 fluctuated within a range of approximately ±50 mm from the target value. Therefore, it was confirmed that the water level could be extremely stabilized.

[0055] [Effect] According to the above example, a relatively small change in the water level is dealt with by adjusting the opening of the sub-valve V1. On the other hand, the opening of the parent valve V2 is determined from an opening function based on the flow rate (total flow rate) measured by the sensors SE3 to SE5. Therefore, even if the amount of deaerated water supplied from one deaerator 13 to multiple boilers 14 changes significantly due to a change in the number of boilers 14 in operation, the parent valve V2 is controlled to a preset opening that can deal with such a change. Thus, according to the above example, instead of switching the control target between the parent valve V2 and the sub-valve V1, the parent valve V2 and the sub-valve V1 are controlled in parallel, and the parent valve V2 and the sub-valve V1 each bear the magnitude of the water level change. Therefore, even if the operating conditions of multiple boilers 14 change, it is possible to stabilize the water level of the deaerated water in the deaerator 13 shared by multiple boilers.

[0056] According to the above example, so-called feedforward control is performed by correcting the opening of the master valve V2 based on the steam flow rate supplied to the deaerator 13, regardless of whether or not a large pressure fluctuation actually occurs in the deaerator 13. Therefore, it is possible to stabilize the water level of the deaerator 13 while suppressing the pressure fluctuation in the deaerator 13.

[0057] According to the above example, the opening of the parent valve V2 is controlled based on one opening function selected from the multiple opening functions based on the number of operating boilers 14. Therefore, since an appropriate opening function is selected based on the number of operating boilers 14, it becomes possible to control the opening of the parent valve V2 with higher accuracy in accordance with the flow rate of deaerated water flowing through the multiple boilers 14 when the number of operating boilers 14 changes.

[0058] According to the above examples, the opening function can be a linear function in which the opening of the parent valve V2 monotonically increases with the flow rate of the deaerated water flowing into the multiple boilers 14, or a broken-line function in which the opening of the parent valve V2 monotonically does not decrease with the flow rate of the deaerated water flowing into the multiple boilers 14. In this case, the opening function becomes extremely simple, making it possible to set the opening function easily.

[0059] [Variations] The disclosure in this specification should be considered to be illustrative and not restrictive in all respects. Various omissions, substitutions, modifications, etc. may be made to the above examples without departing from the scope of the claims and the gist thereof.

[0060] (1) The opening and closing of the sub-valve V1 and the parent valve V2 may be switched between manual control and automatic control depending on the water level in the deaerator 13. For example, when the water level in the deaerator 13 falls outside a predetermined range, the sub-valve V1 and the parent valve V2 may be manually controlled so that the steam turbine power generation system 1 can be immediately stopped.

[0061] (2) In the above example, condensed water is supplied from the condenser 12 to the deaerator 13, but this is not limited thereto, and water other than condensed water may be supplied to the deaerator 13 from a water supply device other than the condenser 12. Alternatively, both the condensed water from the condenser 12 and water from a water supply device other than the condenser 12 may be supplied to the deaerator 13.

[0062] (3) In the above example, the child valve V1 is disposed in the pipe D3, the parent valve V2 is disposed in the pipe D4, and the pipe D4 branches off from the pipes D2 and D3, but the configuration of the pipes in which the child valve V1 and the parent valve V2 are disposed is not limited to this. For example, the pipe D3 may branch off and extend from the pipes D2 and D4 so as to bypass the parent valve V2 disposed in the pipe D4. Alternatively, the pipe (first pipe) in which the child valve V1 is disposed and the pipe (second pipe) in which the parent valve V2 is disposed may each extend between a water supply device such as the condenser 12 and the deaerator 13, and may extend in parallel with each other.

[0063] [Other examples] Example 1. One example of a valve control device includes a deaerator configured to remove gas contained in water supplied from a water supply device, a child valve provided on a first pipe extending between the water supply device and the deaerator, a parent valve provided on a second pipe extending in parallel to the first pipe between the water supply device and the deaerator and configured to adjust a flow rate greater than that of the child valve, a plurality of boilers to which deaerated water deaerated in the deaerator is supplied, a level measuring unit configured to measure the water level in the deaerator, a flow measuring unit configured to measure the flow rate of deaerated water supplied from the deaerator to the plurality of boilers, a memory unit configured to store an opening function indicating the relationship between the flow rate of deaerated water flowing to the plurality of boilers and the opening degree of the parent valve that is preset in accordance with the flow rate, and a control unit. The control unit is configured to execute a first process of controlling the opening of the child valve so that the water level measured by the level measurement unit approaches a predetermined target value, and a second process of controlling the opening of the parent valve so that the opening is determined from the opening function stored in the storage unit based on the flow rate measured by the flow rate measurement unit. In this case, a relatively small fluctuation in the water level is dealt with by adjusting the opening of the child valve. On the other hand, the opening of the parent valve is determined from the opening function based on the flow rate measured by the flow rate measurement unit. Therefore, even if the amount of deaerated water supplied from one deaerator to multiple boilers fluctuates greatly due to a change in the number of operating boilers, the parent valve is controlled to have a preset opening that can deal with such fluctuations. In this way, in the device of Example 1, the control target is not switched between the parent valve and the child valve, but the parent valve and the child valve are controlled in parallel, and the parent valve and the child valve each bear the magnitude of the fluctuation in the water level. Therefore, even if the operating conditions of the multiple boilers change, it is possible to stabilize the water level of the deaerator in the deaerator shared by the multiple boilers.

[0064] Example 2 The device of Example 1 may further include a steam flow rate measurement unit configured to measure the flow rate of steam supplied to the deaerator, and the second process may include determining an opening degree calculated from the opening degree function stored in the memory unit based on the flow rate measured by the flow rate measurement unit, correcting the determined opening degree based on the steam flow rate measured by the steam flow rate measurement unit, and controlling the opening degree of the parent valve to the corrected opening degree. Incidentally, the opening degree of the parent valve calculated from the opening degree function may be excessive for the flow rate of the deaerator water supplied to the multiple boilers. In this case, the amount of condensate water supplied to the deaerator increases, so that the steam supplied to the deaerator is used more for heat exchange with the condensate water, and the pressure in the deaerator decreases. Therefore, the steam flow rate supplied to the deaerator increases, and the pressure fluctuation in the deaerator may become large. On the other hand, the opening degree of the parent valve calculated from the opening degree function may be excessive for the flow rate of the deaerator water supplied to the multiple boilers. In this case, the amount of condensate supplied to the deaerator is reduced, so that the steam supplied to the deaerator is not used much for heat exchange with the condensate, and the pressure in the deaerator rises. Therefore, the steam flow rate supplied to the deaerator is reduced, and the pressure fluctuation in the deaerator may become large. Therefore, as in the device of Example 2, the steam flow rate supplied to the deaerator is measured, and the opening of the parent valve is corrected based on the measured value. For example, when the steam flow rate supplied to the deaerator is greater than a predetermined threshold, the opening of the parent valve is corrected to be smaller. On the other hand, when the steam flow rate supplied to the deaerator is smaller than another predetermined threshold, the opening of the parent valve is corrected to be larger. In this way, regardless of whether or not a large pressure fluctuation actually occurs in the deaerator, the opening of the parent valve is corrected based on the steam flow rate supplied to the deaerator, so-called feedforward control is performed. Therefore, it is possible to stabilize the water level of the deaerator in the deaerator while suppressing the pressure fluctuation in the deaerator.

[0065] Example 3 In the apparatus of Example 1 or Example 2, the memory unit is configured to store a plurality of opening functions showing the relationship between the flow rates of the deaerated water flowing through the plurality of boilers and the opening of the parent valve preset according to the flow rates, and the second process may include selecting one opening function from the plurality of opening functions stored in the memory unit based on the number of operating boilers, and controlling the opening of the parent valve to the opening calculated from the one selected opening function based on the flow rate measured by the flow rate measurement unit. In this case, since an appropriate opening function is selected based on the number of operating boilers, it becomes possible to control the opening of the parent valve with higher accuracy in accordance with the flow rate of the deaerated water flowing through the plurality of boilers when the number of operating boilers changes.

[0066] Example 4: In any of the devices of Examples 1 to 3, the opening function may be a linear function in which the opening of the parent valve increases monotonically with respect to the flow rate of the deaerated water flowing to the multiple boilers, or a broken-line function in which the opening of the parent valve does not decrease monotonically with respect to the flow rate of the deaerated water flowing to the multiple boilers. In this case, the opening function is extremely simple, so that it is possible to easily set the opening function.

[0067] Example 5. One example of a valve control method is a method for controlling a child valve provided on a first pipe extending between a deaerator configured to remove gas contained in water supplied from the water supply device and the water supply device, and a parent valve provided on a second pipe extending between the water supply device and the deaerator in parallel with the first pipe and configured to adjust a flow rate greater than that of the child valve. The method includes a first step of measuring the water level in the deaerator and controlling the opening of the child valve so that the measured water level approaches a predetermined target value, and a second step of measuring the flow rate of deaerated water supplied from the deaerator to multiple boilers and controlling the opening of the parent valve based on the measured flow rate so that the opening is calculated from an opening function showing the relationship between the flow rate of deaerated water flowing from the deaerator to the multiple boilers and the opening of the parent valve preset according to the flow rate. In this case, the same action and effect as the device of Example 1 can be obtained.

[0068] Example 6 In the method of Example 5, the second step may include measuring the flow rate of deaerated water supplied from the deaerator to the plurality of boilers, and determining an aperture calculated from the aperture function based on the measured flow rate, measuring the flow rate of steam supplied to the deaerator, and correcting the determined aperture based on the measured steam flow rate, and controlling the aperture of the parent valve to the corrected aperture. In this case, the same effects as those of the device of Example 2 can be obtained.

[0069] Example 7 In the method of Example 5 or Example 6, the second step may include selecting one of a plurality of opening functions that indicate a relationship between the flow rate of the deaerated water flowing to the plurality of boilers and an opening of the parent valve that is preset according to the flow rate, based on the number of operating boilers, and measuring the flow rate of the deaerated water supplied from the deaerator to the plurality of boilers, and controlling the opening of the parent valve so that the opening is equal to the opening calculated from the one opening function selected based on the measured flow rate. In this case, the same effects as those of the device of Example 3 can be obtained.

[0070] Example 8 In any of the methods of Examples 5 to 7, the opening function may be a linear function in which the opening of the parent valve increases monotonically with respect to the flow rate of the deaerated water flowing into the boilers, or a broken-line function in which the opening of the parent valve does not decrease monotonically with respect to the flow rate of the deaerated water flowing into the boilers. In this case, the same effects as those of the device of Example 4 can be obtained. [Explanation of symbols]

[0071] 1...steam turbine power generation system (valve control device), 2...power generation equipment, 12...condenser (water supply unit), 13...deaerator, 14...boiler, Ctr...controller (control unit), C2...memory (storage unit), D2, D3...piping (first piping), D4...piping (second piping), F1, F2...opening function, SE1...sensor (level measurement unit), SE3 to SE5...sensors (flow measurement unit), SE6...sensor (steam flow measurement unit), V1...child valve, V2...parent valve.

Claims

1. a deaerator configured to remove gas contained in the water supplied from the water supply; a sub-valve provided in a first pipe extending between the water supply device and the deaerator; a parent valve provided in a second pipe extending in parallel with the first pipe between the water supply device and the deaerator, the parent valve being configured to be capable of adjusting a flow rate greater than that of the child valve; A plurality of boilers to which deaerated water deaerated in the deaerator is supplied; A level measuring unit configured to measure a water level in the deaerator; a flow rate measuring unit configured to measure a flow rate of deaerated water supplied from the deaerator to the plurality of boilers; a storage unit configured to store an opening function indicating a relationship between a flow rate of the deaerated water flowing through the plurality of boilers and an opening degree of the master valve that is preset in accordance with the flow rate; A control unit. The control unit is a first process for controlling an opening degree of the sub-valve so that the water level measured by the level measuring unit approaches a predetermined target value; and a second process of controlling the opening of the parent valve so that the opening becomes the opening calculated from the opening function stored in the memory unit, based on the flow rate measured by the flow rate measuring unit.

2. a steam flow rate measuring unit configured to measure a steam flow rate supplied to the deaerator; The second process includes: determining an opening calculated from the opening function stored in the memory unit based on a flow rate measured by the flow rate measuring unit; correcting the determined opening degree based on a steam flow rate measured by the steam flow rate measuring unit; and controlling an opening degree of the master valve so as to achieve the corrected opening degree.

3. the storage unit is configured to store a plurality of opening functions indicating a relationship between a flow rate of the deaerated water flowing through the plurality of boilers and an opening rate of the master valve that is preset according to the flow rate, The second process includes: selecting one opening function from the plurality of opening functions stored in the storage unit based on the number of operating boilers; 3. The device according to claim 1, further comprising: controlling an opening of the master valve so that the opening becomes an opening calculated from the one selected opening function, based on the flow rate measured by the flow rate measuring unit.

4. The device described in claim 1, wherein the opening function is a linear function in which the opening of the parent valve is monotonically increasing with respect to the flow rate of the degassed water flowing to the multiple boilers, or a piecewise linear function in which the opening of the parent valve is monotonically non-decreasing with respect to the flow rate of the degassed water flowing to the multiple boilers.

5. A valve control method for controlling a child valve provided in a first pipe extending between a deaerator configured to remove gas contained in water supplied from a water supply device and the water supply device, and a parent valve provided in a second pipe extending in parallel with the first pipe between the water supply device and the deaerator, the parent valve being configured to be able to adjust a flow rate greater than that of the child valve, comprising: a first step of measuring a water level in the deaerator and controlling an opening degree of the sub-valve so that the measured water level approaches a predetermined target value; a second step of measuring a flow rate of deaerated water supplied from the deaerator to a plurality of boilers, and controlling the opening of the parent valve based on the measured flow rate so that the opening is obtained from an opening function showing the relationship between the flow rate of the deaerated water flowing from the deaerator to the plurality of boilers and the opening of the parent valve that is preset in accordance with the flow rate.

6. The second step includes: measuring a flow rate of deaerated water supplied from the deaerator to a plurality of boilers, and determining an opening degree calculated from the opening degree function based on the measured flow rate; measuring a steam flow rate supplied to the deaerator, and correcting the determined opening degree based on the measured steam flow rate; The method according to claim 5 , further comprising: controlling an opening degree of the master valve so as to achieve the corrected opening degree.

7. The second step includes: selecting one opening function from a plurality of opening functions that indicate a relationship between a flow rate of the deaerated water flowing through the plurality of boilers and an opening of the parent valve that is preset according to the flow rate, based on the number of operating boilers of the plurality of boilers; 7. The method according to claim 5 or 6, comprising measuring a flow rate of deaerated water supplied from the deaerator to a plurality of boilers, and controlling the opening of the master valve based on the measured flow rate so as to achieve an opening calculated from the selected one of the opening functions.

8. The method according to claim 5, wherein the opening function is a linear function in which the opening of the parent valve monotonically increases with the flow rate of the degassed water flowing into the multiple boilers, or a piecewise linear function in which the opening of the parent valve monotonically does not decrease with the flow rate of the degassed water flowing into the multiple boilers.

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