JPH03134402A - Feed water flow controller for electric power plant - Google Patents

Abstract

PURPOSE:To enable stable supply of feed water over a wide flow rate range, from lower to higher flow rates, by regulating the opening of a feed water control valve based on a value detected by a second flow rate detector when there is no output from a setter, and regulating the opening of the valve based on a value detected by a first flow rate detector when there is an output from the setter. CONSTITUTION:When a deviation value for a feed water flow rate equal to, for example, 40% of a maximum flow rate, a set value in a setter 31 is so selected that the setter 31 produces an output according to an input thereto, and an output from a switch 30 is so determined that transfer from a signal produced by an adder-subtracter 43 to a signal produced by an adder-subtracter 28 can be made when the setter 31 gives an output. When the feed water flow rate is not more than 40% of the maximum flow rate, the opening of a feed water flow control valve 10 is regulated based on a value detected by a flow rate detector 25 provided in a piping on the inlet side of a starting feed water pump 24 and a value detected by a temperature detector 26. When the feed water flow rate exceeds 40%, the opening of the valve 10 is regulated based on a value detected by a flow rate detector 25 provided in a pipe on the outlet side of the valve 10 and a value detected by the temperature detector 26. It is thereby possible to perform a stable feed water flow control.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a water supply flow rate control device for a power generation plant using steam power, and in particular to a power generation plant with improved control characteristics during small flow operation. This invention relates to a water supply flow rate control device.

(Prior technology) The flow rate of water supplied to the steam generator of a steam power generation plant is determined by a system in which water is collected in a condenser attached to a steam turbine that drives a generator, and a water pump and a water regulating valve are inserted in series. When the water is returned to a steam generating means such as an evaporator through a pipe provided with the water, the opening degree of the water supply control valve is controlled while operating the water supply pump. In this case, multiple water supply pumps are usually used in parallel, and when the power generation plant has a large output and requires a large amount of water supply, for example, a turbine-driven pump that uses the steam generated by the plant is used, such as when starting up the power generation plant. When the amount of steam produced is small and the flow rate of water supply is low, an electric motor-driven pump is used instead.

The main parts of the water/steam system piping and its control system during full control of such a small flow rate of water supply are as shown in Figure 4, for example, in the steam generation system of a nuclear power plant using a fast breeder reactor. In addition, a feed water heater 8. Start-up water pump 24.
Feed water heater8. A water supply control valve 10 and an evaporator 5 are inserted in this order to reach a steam/water separator 23. Steam components from the steam separator 23 are piped to a superheater via a stop valve 32, and moisture is similarly piped to be led to a condenser. A main feed water flow rate detector 25 is provided on the outlet side pipe of the feed water control valve 10, and a steam temperature detector 26 is provided on the outlet side pipe of the evaporator 5, and their output signals are sent to the feed water flow rate control device 42. has been entered. The output signal of the water supply flow rate control device 42 is connected to the water supply control valve 10.

Here, we will talk about a case where small flow rate water supply control is required, when the reactor is started and the output is increased to, for example, 40% of the rated output.The water supply flow rate is 10% of the maximum flow rate until the reactor starts nuclear heating. %, and then nuclear heating of the reactor is started, and the feed water flow rate is increased from 10% to 40% before evaporation occurs from the evaporator 5.

The water supply flow rate during this period is controlled by adjusting the water supply control valve 10 based on the detected values of the detectors 25 and 26. In this case, the details of the feed water flow rate control device 42 are as shown in FIG.
7 to automatically change the set value corresponding to the water supply flow rate from 210% to 40% and give it to the adjustment calculator 28, and after taking the deviation from the output signal of the main water supply flow rate detector 25,
This is passed through the PI calculator 29 and used as an opening/closing signal for the water supply control valve 10.

(Problem to be Solved by the Invention) In the above-described water supply flow rate control device, the main water supply flow rate detector 2
5 is used in a wide range from the low flow rate range of 10% to 40% of the water supply flow rate up to the rated flow rate. Control sometimes became unstable.

An object of the present invention is to provide a water supply flow rate control device for a power plant that can stably control the water supply flow rate from a low flow rate range to a high flow rate range.

[Structure of the invention]

(Means for Solving the Problems) In the present invention, a water supply pump and a water supply control valve are inserted in a water supply pipe to an evaporator that is supplied with heat and supplies steam to a turbine for driving a generator. In a power plant water supply flow rate control device that adjusts the opening degree of a water supply control valve based on the detected value of a flow rate detector, the system is installed in parallel with a water supply pump dedicated for relatively high flow rates. A second flow rate detector provided in the flow path of the dedicated water supply pump, and a predetermined value for the deviation between the detected values of this second flow rate detector and the first flow rate detector provided in the water supply pipe. A setting device that outputs an output when the setting device outputs an output of The opening degree of the water supply control valve is adjusted by a signal based on the detected value of the first flow rate detector, and when there is an output from the setting device, the opening degree of the water supply control valve is adjusted by a signal based on the detection value of the first flow rate detector through the switch. I made it so that it would be done.

(Function) When the flow rate is relatively low, the deviation between the detected values of the first flow rate detector and the second flow rate detector is large and there is no output from the setting device.
The opening degree of the water supply control valve is controlled based on the detected value of the second flow rate detector, the water supply flow rate increases and the deviation between the detected values of the first flow rate detector and the second flow rate detector decreases, When this becomes less than a predetermined value and the setting device outputs an output, the opening degree of the water supply control valve is thereafter controlled based on the detected value of the first flow rate detector. When the flow rate is relatively low, the second
The accuracy of the detection value of the first flow rate detector is good, and as the flow rate increases, the accuracy of the detection value of the first flow rate detector also improves, so it is possible to always control the water supply flow rate with high precision regardless of the size of the water supply flow rate. .

(Example) As an example of the present invention, a fast breeder reactor (hereinafter FBR) will be described below.
1 to 3, a description will be given of an apparatus applied to a water supply flow port control device for a type nuclear power plant.

Fig. 3 is a control system diagram of an FBR type nuclear power plant. System piping 4
5 is provided, and a coolant made of liquid sodium is circulated through this to provide heat generated in the reactor vessel 1 to the intermediate heat exchanger 2. On the secondary side of the intermediate heat exchanger 2, a secondary main cooling system piping 46 in which a superheater 4, an evaporator 5, and a secondary main cooling system circulation pump 6 are inserted is provided, and a cooling system also made of liquid sodium is provided. The heat exchanged in the intermediate heat exchanger 2 is transferred to the evaporator 5 and the superheater 4.
It is intended to be given to

The secondary sides of the superheater 4 and the evaporator 5 are connected in series, and these constitute a part of the circulation path of the steam system described below. That is, the secondary side of the superheater 4 is pipe-connected to the high-pressure turbine 13 via the steam control valve 11, and superheated steam generated on the secondary side of the evaporator 5 and superheated in the superheater 4 is supplied to the high-pressure turbine 13. It has become so. The exhaust side of the high-pressure turbine 13 is connected to energize the low-pressure turbine 14, which rotates a generator 15 that is coupled to these turbines 13,14.

A condenser 16 is provided on the exhaust side of the low pressure turbine 14,
The water supply pipe 33 connected thereto includes a condensate pump 7, a feed water heater 8A, a main water pump 9 connected in parallel, and a starting water pump 24. A feed water heater 8B and a feed water control valve 10 are sequentially inserted to reach the secondary side of the evaporator 5, so that water condensed in the condenser 16 is circulated back to the evaporator 5. Further, from the artificial side of the steam control valve 11, a bypass path is provided which leads to a condenser 16 through which a turbine bypass valve 12 is inserted.

An output command device 17 is provided as a control system for such a nuclear power generation device, and the output signal of this power command device F is sent to the reactor power control device L8. It is connected to the primary main cooling system flow rate control device 19, the secondary main cooling system flow rate control device 20, and the feed water flow 2 control device 21, respectively.

The reactor power control device 18 includes a temperature detector 34 provided at the outlet of the primary main cooling system piping 45 from the reactor vessel 1 and a neutron detector 35 provided inside the reactor vessel 1. A value is input, and its output is connected to control a control rod for adjusting the reactor power in the reactor vessel 1.

The primary main cooling system flow control device 19 includes a rotation speed detector 36 of the primary main cooling system circulation pump 3 and a flow rate detector 37 provided on the discharge side of the primary main cooling system circulation pump 3. A value is input, and its output is connected to control the rotation speed of the primary main cooling system circulation pump 3.

The detection value of the flow rate detector 38 provided on the discharge side of the secondary main cooling system circulation pump 6 is inputted to the secondary main cooling system flow rate control device 20, and the output thereof is input to the secondary main cooling system circulation pump 6. Connected to control the rotation speed.

The feed water flow rate control device 21 includes a temperature detector 26 provided on the secondary side outlet pipe of the evaporator 5, a flow rate detector 25 provided on the outlet side pipe of the feed water control valve 10, and a temperature detector 26 provided on the outlet side pipe of the feed water control valve 10.
The detected values of the differential pressure gauge 39 installed between the inlet and outlet of the starting water pump 24 are inputted, and in addition to these, the detected values of the flow rate detector 40 installed on the inlet side piping of the starting water supply pump 24 are inputted, and the output One for controlling the opening degree of the water supply control valve IO and the other for controlling the rotation speed of the main water supply pump 9 are derived.

In addition to these control devices, a main steam pressure control device 22 is provided, to which the detected value of the pressure detector 4■ provided on the inlet side piping of the steam control valve 11 is inputted, and
Output lines are derived to control the opening degrees of the steam control valve 11 and the turbine bypass valve 12, respectively.

Next, the effect of this will be described.

Relatively large power, for example 40% to 10% of the rated output of a nuclear reactor
During operation in the 0% range, the output command device 17
When a set value corresponding to a desired plant output is given, a corresponding plant output command signal is sent to the reactor power control device 18, the primary main cooling system flow control device 19, the secondary main cooling system flow control device 20, and The information is transmitted to the water supply flow rate control device 21, respectively. When the set value of the plant output is increased or decreased from the current plant output, the plant output command signal is transmitted to each of the above-mentioned control devices at a predetermined rate of change.

At this time, the reactor power control device 18 compares the temperature of sodium at the outlet of the reactor vessel 1 detected by the temperature detector 34 with this plant output command signal, and inserts control rods (all not shown) into the reactor core. The reactor output is controlled to match the set value of the plant output by adjusting the amount. At this time, in order to compensate for the thermal delay in the temperature detection value of sodium, the output signal of the neutron detector 35 is also used to improve the responsiveness and stability of the control.

Similarly, the primary main cooling system flow rate control device 19 includes a flow rate detector 3
The circulation flow rate of the primary main cooling system detected by 7 and the rotation speed signal of the primary main cooling system circulation pump 3 detected by the rotation speed detector 36 are compared with the plant output command signal to determine the circulation flow rate of the primary main cooling system. The rotation speed of the pump 3 is adjusted to control the circulation flow rate of the primary main cooling system to a value corresponding to the set value of the plant output.

Similarly, the secondary main cooling system flow rate control device 20 includes a flow rate detector 3
The rotation speed of the secondary main cooling system circulation pump 6 is adjusted by comparing the detected circulation flow rate of the secondary main cooling system with the plant output command signal, and the circulation flow rate of the secondary main cooling system is adjusted to the set value of the plant output. It is controlled so that the value corresponds to .

Similarly, the water supply flow rate control device 21 adjusts the opening degree of the water supply control valve 10 so that the steam temperature at the outlet of the evaporator 5 detected by the temperature sensor 26 is maintained at a predetermined constant value, and also controls the opening degree of the water supply control valve 10 using a differential pressure gauge. Control is performed to adjust the rotational speed of the main water supply pump 9 so that the differential pressure between the inlet and the outlet of the water supply control valve 10 detected by the main water supply control valve 39 becomes a constant value.

Furthermore, when the set value of the plant output is increased or decreased from the current plant output, the detected value of the flow rate detector 25 is compared with the plant output command signal to improve control responsiveness.

The main steam pressure control device 22 also adjusts the opening degree of the steam control valve 11 so that the main steam pressure detected by the pressure detector 41 is maintained at a constant value. Note that control is performed to open the turbine bypass valve 12 when the main steam pressure increases rapidly.

In this way, the flow rate of the main cooling system is controlled to be substantially proportional to the plant output command signal, and at the same time, the reactor output is adjusted, making the turbine generator output follow the reactor output.

On the other hand, when the reactor is started up, for example, 40
We will discuss the control that takes place up to %.

In this case, the reactor power control device 18 , the primary main cooling system flow rate control device 19 , the secondary main cooling system flow rate control device 20 , and the feed water flow rate control device 21 are separated from the output command device 17 . The primary main cooling system circulation pump 3 and the secondary main cooling system circulation pump 6 are then connected to the primary main cooling system flow control device 19 and the secondary main cooling system flow control device 20, respectively.
The circulating flow rate in each prefecture is controlled to be constant. In addition, the reactor power control device 18 controls the control rods (
(not shown) is controlled.

In a water supply system including a water vapor system water supply pipe 33, the main water supply pump 9 is separated and the starting water supply pump 24 is used.

The details of the main parts from the condensate pump 7 including the start-up water supply pump 24 to the superheater 4 are as shown in FIG. The steam is led to the superheater 4 through a pipe in which a stop valve 32 is inserted, and the moisture is led to the condenser IG. The detected values of the flow rate detector 25, the temperature sensor 26, and the flow rate detector 40 are input to the feed water flow rate control device 21, and the valve opening degree of the feed water regulating valve 10 is controlled based on these detected values.

Here, the detailed configuration of the water supply flow rate control device 21 is as shown in FIG.
7 is provided, and its output is connected to addition/subtraction calculators 28 and 43. The other inputs of the addition/subtraction calculations rt28 and rt43 are connected to the respective outputs of the flow rate detector 25 and the flow rate detector 40. Further, an addition/subtraction calculator 44 which receives input from the flow rate detector 25 and the flow rate detector 40 is provided, and its output is connected to the setting device 31 so as to control opening/closing of the switch 30 . Both outputs of the addition/subtraction calculators 28 and 43 are connected to the switch 30, and the output thereof is connected to the water supply control valve 10 via the PI calculator 29.

Here, the operation from the start of the nuclear reactor to the normal operating state, that is, for example, to 40% or more of the rated output, will be described.

Until the control rods are withdrawn by the reactor power control device 18 and nuclear heating of the reactor begins, the feed water flow rate is 10% of the maximum flow rate.
It is maintained at about %. Next, the control rods are withdrawn and nuclear heating of the reactor begins, but the amount of heat generated increases and the evaporator 5
Until sufficient generated steam is secured, the stop valve 32 is closed and the water vapor coming out of the evaporator 5 is recycled to the full amount condenser 16 via the steam separator 23. During this period, the water supply flow rate, which is the recirculation flow rate, is controlled by the water supply flow rate control device 21 so as to increase sequentially from 10% to 40% of the maximum flow rate.

In the feed water flow rate control device 21, a function generator 27 adjusts the feed water flow rate from 10% to 4% according to the detected value of the steam temperature detector 26.
A flow rate value signal corresponding to 0% is output, and this signal is compared with each detection signal of the flow rate detector 25 and the flow rate detector 40 in the addition/subtraction calculator 28 and the addition/subtraction calculator 43, respectively, and each deviation value is outputted to the switch 30. One of them is selected, and after passing through the PI calculator 29, the opening degree of the water supply control valve IO is adjusted.

On the other hand, the flow rate detector 25 is also input to the addition/subtraction calculator 44.
As for each detection signal of the flow rate detector 40, the detection value error of the flow rate detector 25 decreases as the water supply flow rate increases, so the detection values of the flow rate detector 25 and the flow rate detector 40 become close to each other.
Therefore, the comparison deviation value between the two decreases.

Here, the setting value of the setting device 31 is set so that when this deviation value gradually decreases and reaches the deviation value at the time of water supply flow rate of 40% of the maximum flow rate, the output of the setting device 3I is generated by the input. In addition, if the output of the switch 30 is set so that the signal of the adder/subtractor 43 is switched to the signal of the adder/subtractor 28 when the output of the setting device 31 occurs, the water supply flow rate will be 40% of the maximum flow rate. Until then, the opening degree of the water supply control valve 10 is adjusted based on the detection values of the flow rate detector 40 provided on the inlet side piping of the starting water supply pump 24 and the temperature detector 26, and the water supply flow rate exceeds 40%. As described above, the opening degree of the water supply regulating valve 10 is adjusted based on the detection values of the flow rate detector 25 and the temperature detector 26 provided on the outlet side piping of the water supply regulating valve 10.

As a result, the water supply flow rate up to the maximum flow rate of 4096 is controlled using the flow rate detector 40 with a small maximum rating, so the flow rate detection accuracy does not decrease, and stable overall control of the water supply flow is possible even when the water supply flow rate is low. can be done.

[Effects of the Invention] According to the present invention, it is possible to provide a water supply flow rate control device for a power plant that can provide stable water supply from a low flow rate region to a high flow rate region.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing the details of the water supply flow rate control device in Figure 2, Figure 2 is a piping diagram showing the main parts of Figure 3, and Figure 3
The figure is a control system diagram of an FBR type nuclear power plant to which an embodiment of the present invention is applied, Figure 4 is a piping diagram showing the main parts of the steam generation system of a conventional FBR type nuclear power plant, and Figure 5 is a 5 is a circuit diagram showing the water supply flow rate control device of FIG. 4. FIG. 5...Evaporator 9...Main water supply pump lO
... Water supply control valve 13 ... High pressure turbine 14
... Low pressure turbine 15 ... Generator ( 24 ... Water supply pump for starting 25.40 ... Flow rate detector 30 ... Switching device 31 ... Setting device 3
3...Water supply piping

Claims (1)

[Claims] 1. A water supply pump and a water supply control valve are inserted in the water supply pipe to the evaporator that receives heat and supplies steam to the turbine for driving the generator, and based on the detection value of the flow rate detector installed in the water supply pipe, In the water supply flow rate control device for a power generation plant that adjusts the opening degree of the water supply control valve, the water supply pump, which is installed in parallel with the water supply pump dedicated to relatively high flow rates, is installed in a flow path of the water supply pump, which is dedicated to relatively low flow rates. Output when the deviation between the detected values of the second flow rate detector provided and the second flow rate detector and the first flow rate detector provided in the water supply pipe becomes equal to or less than a predetermined value. A setting device and a switching device that selects and outputs one of two inputs depending on the presence or absence of an output from the setting device are provided, and when there is no output from the setting device, the detected value of the second flow rate sensor is changed through the switching device. The opening degree of the water supply control valve is adjusted by a signal based on the detection value of the first flow rate detector through the switching device when there is an output of the setting device. 1. A water supply flow rate control device for a power generation plant, characterized in that the water flow rate is adjusted.