JPS58105306A - Water supply controller - Google Patents

Abstract

PURPOSE:To realize a stable control of the water supply from a low load region to a high load region, by using a control valve to control the flow rate of water less than the level equivalent to the lower limit speed of revolution of a water supply pump and varying the speed of revolution of the pump to control the flow rate of water more than the level equivalent to the lower limit of speed of revolution of the pump. CONSTITUTION:A high-rank selector 15 selects a water supply request command 14a and delivers a revolving speed command 15a. In this case, the request command is given for the quantity of water more than the level equivalent to the lower limit of speed of revolution of a water supply pump 2. Therefore the command 14a is given to a revolving speed control circuit 16 in the form of the output signal of the selector for the flow rate of water to be supplied. Then the opening of a steam increment/decrement valve 3 is controlled to control the speed of revolution of the pump 2. In case the selector 15 selects the setting signal 10a for the lower limit speed of revolution of the pump 2, the command 15a is subtracted by the command 14a through a subtractor 17. Then the difference signal 17a is subtracted by the full-opened signal 18a of a full- opened setter 18 through a subtractor 19. The output signal 19a is led to a control circuit 20 for opening of control valve to control the opening of a control valve 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a water supply control system for nuclear power generation facilities, particularly for controlling the rotational speed of a turbine-driven water supply pump and controlling the opening of a flow rate regulating valve. Therefore, the present invention relates to a water supply control device that adjusts the amount of water supplied to a boiler.

TECHNICAL BACKGROUND OF THE INVENTION Conventionally, water supply flow rate control for thermal power generation equipment is controlled by an electric motor-driven water pump (hereinafter referred to as MP) or, in some cases, a control valve connected to the outlet side of the MP. In the case of a water supply pump (hereinafter referred to as TP), control was performed by changing the rotational speed of a turbine directly connected to the TP. Alternatively, since it is generally a boiler type constant pressure boiler, the low load area with a small flow rate is controlled by a control valve connected to the Mp outlet INK, and in the high load area with a large flow rate, MP operation is switched to TP operation, and TPO rotation speed control is performed. Therefore, the water supply flow rate is controlled. However, when pressure-transforming operation is performed, including the furnace path of the boiler, the system head of the water supply system changes significantly depending on the load, and in the low load range, the required discharge pressure to the water pump becomes low. Since the driving power of the pump is reduced, it becomes possible to operate the TP down to a low load range by relying on turbine bleed air.

Problems with the Background Art However, if the water supply flow rate is controlled by the TP up to the low load range, the rotational speed control range of the TP will greatly expand)
In the low load range, the rotational speed of the TP is required to be very low, and at the same time the water supply flow rate decreases, resulting in poor controllability.Furthermore, the lower limit rotational speed is naturally limited due to the structural characteristics of the water supply pump. There was a problem that caused the TPO
There has been a need for a water supply control device that is capable of controlling the water supply flow rate in a low flow rate range and with a rotational speed below the lower limit rotational speed.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems.
To provide a water supply control device capable of controlling the water supply flow rate equivalent to the lower limit rotational speed or more by changing the TPO rotational speed, thereby performing stable control from a low load area to a high load area.

Summary of the Invention The present invention controls the flow rate in a high load area where the flow rate is high by changing the rotational speed of the water supply pump, and in the low load area where the flow rate is low by changing the valve opening degree of a control valve connected to the water supply pump. Water supply with flow control! This water supply control device, which is a T control device, includes a first circuit that compares and calculates the rotation speed of the water supply pump with a preset lower limit rotation speed and generates a setting signal, as well as a first circuit that generates a set signal by comparing the rotation speed of the water supply pump with a preset lower limit rotation speed. A circuit I82 generates a water supply request command by comparing the actual flow rate with the corresponding actual flow rate, and the setting signal which is the output of the first circuit and the water supply request command which is the output of the second circuit are input signals, The high-level selector selects and outputs the larger input signal among the input signals 7 and 7. The water supply control device of the present invention further subtracts the rotation speed command, which is the output signal of the high-level selector, from the water supply request command of the second circuit, and uses the resulting signal to control the fully open valve of the preset control valve. If the high-level selector selects the water supply request command which is the output of the second circuit, the rotation speed of the water supply pump is controlled according to this water supply request command. At the same time, the control valve is set to be fully open or completely open. or,
When the high-level selector selects the setting signal that is the output of the first circuit, the water supply pump is operated at the lower limit rotation speed, and the valve opening of the control valve is controlled according to the required water supply flow rate. Since the present invention is configured as described above, it is possible to provide a device that performs stable water supply control from a low load area to a high load area.

Embodiment of the Invention FIG. 1 is a diagram showing the main part of the system configuration of an embodiment of the water supply control device of the present invention. In the figure, l is a steam turbine, 2
3 is a feed pump driven by the steam turbine I, and 3 is a steam control valve for adjusting the steam flowing into the steam turbine IK. Changes in the rotation speed of the water supply pump 20 are controlled by the steam control valve 3.
This is done by adjusting the opening degree. Therefore, the water supply flow rate to the boiler (not shown) is controlled in a low load region by the valve opening degree of the control valve 4 for adjusting the water supply flow rate, and in the high load region, a control valve 4 is connected in parallel with the control valve 4 in addition to the control valve 4. The bypass valve 5 is fully opened, and the rotational speed of the water supply pump 20 is changed to control the flow rate.

FIG. 2 is a block diagram showing an embodiment of the water supply control device of the present invention. In the figure, 6 is a rotational speed detector for detecting the rotational speed of the water supply pump, and its output signal 61 is input to the monitor switch 7.

8 is a lower limit rotation speed setter for presetting the lower limit value of the rotation speed of the water supply pump, and its output signal 8a is the output signal 6! of the rotation speed detector 6. It is also input to the subtracter 9. The output signal 9a of the subtracter 9 is inputted to a rotational speed controller IOK used as an Ijll circuit, and the calculation result is generated as a setting signal 101. Although the lower limit rotational speed setter 8 is shown as a fixed setting, the pressure of the water supply system,
It is also possible to make it variable (depending on the main steam pressure, etc.). In addition, the setting signal lOa is provided with a rotation 42 controller lO for matching the rotation speed of the water supply pump with the output signal 8a of the lower limit rotation speed setting device 8, but if there is a margin in the lower limit rotation speed, the lower limit There is no substantial problem even if the output signal 8a of the rotational speed setting -8 is used as the setting signal 10a.

11a is the water supply command signal of the water supply pump, which is sent to the subtractor 1 together with the output signal 12a of the discharge flow rate detector 12 of the water supply pump.
3 is input. Deviation signal 13 subtracted by subtracter 13
a is a water supply controller 14 used as a second circuit;
, the water supply controller 14 issues a water supply request command 14
generate a. The rotational speed of the water supply pump is controlled based on this water supply request command 14a.

Water supply request command 14a and lower limit rotational speed setting signal 10a
are both input to the high-level selector 15, and one of the higher-level signals is selected and output as the water pump rotation speed command 15a. Although not shown, it is a matter of course that the water supply request command 14a and the lower limit rotational speed setting signal 10a are modified in their respective circuits so that the signal levels match. 14a is selected and this is output as the rotation speed command 15m, the water supply request command is on the lower limit rotation speed setting device, so the water supply flow rate is output as the output signal of the high level selector 15 as the water supply request command. 1
4 m is given to the rotational speed control circuit 16, which controls the opening degree of the steam regulating valve to increase or decrease the rotational speed of the water supply pump. When the high-level selection 515 selects the lower limit rotational speed setting signal 10m, the rotational speed command 15a, which is the output signal 1 of the high-level selector 15, becomes the setting signal 10m, and this signal is sent to the rotational speed control circuit 16 as follows: is given, and the rotational speed of the water supply pump is controlled to match the lower limit rotational speed setting signal 10a. On the other hand, the rotational speed command 15a, which is also the output signal of the high-level selector 15, is subtracted from the water supply request command 14m in a subtraction 517, and a signal 171 of the difference is generated. is subtracted from the full open signal 18a by the subtracter 19.The output signal 19a of the subtracter 19
becomes the opening degree command of the regulating valve and is guided to the regulating valve opening degree control circuit 20, and the opening degree of the regulating valve is controlled by the output of the regulating valve opening degree control circuit 20.

Next, the operation of one embodiment of the water supply control device of the present invention will be explained using FIG. In Fig. 1g3, 15m is a rotational speed command which is an output signal of the high-level selector 15, and coincides with the lower limit rotational speed setting signal 101. 14a is a water supply request command, and 17m is a signal output from the subtractor 17, which represents the difference between the rotation moderation command 15a and the water supply request command 14a. When the water supply request command 14a changes as shown in FIG. 3, the rotation speed of the water supply pump is controlled by the setting signal 10a, and the output signal 17a of the subtraction $17
has the characteristics shown in FIG. Further, 18m indicates a fully open signal of the control valve. Although not particularly shown in FIG. 2, the control valve full open signal 18a and the lower limit rotational speed setting signal 10a
and are matched in terms of signal level. Therefore, the subtractor 17
The output of the calculation result becomes a signal 171, and the calculation result of the subtracter 19 becomes a signal with the characteristics shown in the output signal 19m. The output signal 19a as a result of this calculation becomes an opening command signal for the control valve. Point A in FIG. 3 is a point where the level of the water supply request command 1411 signal is higher than the lower limit rotation speed setting signal 10m, and the level of the water supply request command 1411 is higher than the rotation speed command 1 which is the output signal of the high-level selector 15.
5a is the same as the water supply request command 14m. Therefore, since the input to the subtractor 17 is the rotational speed command 15m, which is the output signal of the high-level selector 15, and the water supply request command 141, the output signal 1751 of the subtractor 17 is a zero signal, so the subtraction 919 is The output is the fully open signal 18m of the control valve as the output signal 19a. Therefore, from point A onward, the water supply request command 14m is input to the rotation speed control circuit 16, and the rotation speed is controlled based on the water supply request command 14a. The control valve 1JI11 is controlled so that the control valve fully open signal 113a is input to the control circuit 20 so that the control valve is fully open.

Furthermore, when the water supply flow rate is controlled by the control valve, the bypass valve 5 shown in FIG. The flow loss of the control valve 4 is reduced by fully opening the valve. Although the details of this control are not shown, the monitor switch 7 in FIG. 2 detects that the rotation speed of the water supply pump has reached the rotation speed that fully opens the bypass valve 5.
The output contact of the monitor switch 7 outputs a command to fully open the bypass valve. Effects of the Invention The water supply control device of the present invention controls the low load range by a control valve, and controls the rotation speed in the high load range. With this configuration, there is an effect that water supply control can be stably performed over the entire height range. As a result, it is possible to reduce the minimum load of a thermal power plant, and in particular, it is possible to effectively implement middle-scale thermal power operation such as a single-voltage operation plant.

[Brief explanation of the drawing]

Fig. 1 is a main circuit system diagram of a water supply pump to which the water supply control device of the present invention is applied, Fig. 2 is a block diagram showing an embodiment of the water supply control device of the present invention, and Fig. 3 is a diagram of the signal of Fig. It is a characteristic explanatory diagram. 1...Steam turbine 2...Water pump 4...
Control valve 8...lower limit rotation speed setting device 10
...Rotation speed controller 14.Water supply controller 15.High level selector 16.Rotation speed control circuit...Full open setting device Add..Adjustment valve opening control circuit (7317) Agent: Patent attorney agent Kensuke
(1 other person) Figure 1 3 (between trowel → tl!

Claims (1)

[Claims] The flow rate is controlled in a high load area where the flow rate is high by changing the rotational speed of the water supply pump, and the flow rate is controlled in a low load area where the flow rate is low by changing the valve opening of a control valve connected in series with the water supply pump. The water supply control device includes a first circuit that presets the rotational speed of the water supply pump and generates a setting signal by comparing and calculating the rotational speed with the nine lower limit rotational speeds, and a circuit that generates a setting signal by comparing the rotational speed of the water supply pump with the nine lower limit rotational speeds, and a circuit that generates a setting signal between the required water supply request flow rate and the actual flow rate that is actually flowing. A second circuit generates a water supply request command by comparing and calculating the setting signals of these @1 circuits and a second
A high-level selector that takes the water supply request command of the circuit as an input signal and selects and outputs the larger input signal among these human input signals, and a rotation speed command that is the output signal of this high-level selector and the s20 circuit. a water supply request command, which is the output of When a water supply request command as an output is selected, the rotational speed of the water supply pump is controlled according to this water supply request command, and the valve opening degree of the control valve is controlled to be fully open or completely open. , and when the high-level selector selects the setting signal that is the output of the first circuit, the water supply pump is set to the lower limit rotational speed! 11&C, and is configured to control the opening degree of the regulating valve according to the requested water supply flow rate.