JPS597809A - Feeding device for steam generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water supply system for a steam generator, and more particularly to a water supply system for a steam generator suitable for preventing bomb run-out during a condensate pump trip.

BACKGROUND ART As a water supply device that supplies water to a steam generator such as a boiling water nuclear reactor or a boiler, there is one that supplies water to the steam generator from a night stream condenser having a first hot well and a second hot well. This water supply system guides the water in the first hotwell of the condenser to the second hotwell of the condenser through the condensate purification system piping, and then from the second hotwell through the water supply piping to the boiling water reactor (or boiler). ). From the 2nd hotwell to the 1st
There is a pump to allow water to overflow into the hot well. In the condensate purification system piping, three condensate filters, a plurality of condensate filtration demineralizers, and a plurality of condensate demineralizers are installed. The water supply piping has a water supply pump and a supply water heater.

During normal operation, two condensate pumps are operated, and the other one is on standby as a backup unit. When one condensate is tripped, one condensate pump that is on standby is activated. However, when the standby condensate pump, which is a standby unit, cannot be started, an excessive amount of flow flows into the operating condensate pump.

SUMMARY OF THE INVENTION An object of the present invention is to provide a complete water supply system for a steam generator that can reduce the risk of pump run-out of a condensate pump during operation in the event that one condensate pump trips.

A feature of the present invention is that when a condensate pump trips, the flow rate set value of the condensate pipe is temporarily lowered than the first flow rate set value during operation of one condensate pump, and The purpose is to increase the flow rate setting value of the condensate pipe to the first flow rate setting value after a predetermined time has elapsed.

The present invention was made by examining the change in the discharge flow rate of one condensate pump during operation when one conventional condensate pump trips and when a standby condensate pump does not start. The contents of the study will be explained.

When one of the two condensate pumps in operation trips and the backup condensate pump does not start, the flow rate setting value of the condensate purification system piping changes in steps as shown in FIG. At this time,
The flow rate in the condensate purification system piping increases rapidly as shown in FIG. 2 after one condensate pump trips. However, even though the backup condensate pump did not start, it was found that the flow rate of the condensate purification system piping temporarily exceeded the flow rate when one condensate pump was in operation. This is because the discharge flow rate of one condensate pump in operation exceeds the condensate pump run-out flow rate. That is, when two condensate pumps are used as shown in FIG. 3, the discharge flow rate of each condensate pump is equal to or less than the condensate pump flow rate. However, when one condensate pump trips, the discharge flow rate of the remaining condensate pumps temporarily exceeds the condensate pump run-out flow rate.

Exceeding the condensate bomb run-out flow rate is not very desirable in terms of protecting the pump motor.

Based on the above study results, the inventor discovered that if one condensate pump trips and the backup condensate pump does not start, it is sufficient to temporarily lower the flow rate setting value of the condensate purification system piping. did. The present invention has been made based on this discovery.

A water supply system for a steam generator applied to a boiling water reactor, which is a preferred embodiment of the present invention, will be explained based on FIGS. 4, 5, and 6. Steam generated in the reactor pressure vessel of a boiling water reactor, which is a steam generator, is sent to the turbine through the main steam piping. Steam discharged from the turbine is condensed into water in a condenser. This water is returned to the reactor pressure vessel through water supply piping.

Recently, the application of side stream condensers as condensers in boiling water nuclear reactors has been considered. This condenser 1 has a first hot well 3A and a second hot well 3B' which are internally partitioned by a separating wall 2. The first hot well 3A is a condensate system purification pipe (hereinafter referred to as a condensate pipe)
4 to the second hot well 3B. Three condensate pumps 5A, 5B and 5C are provided in the condensate pipe 4. A plurality of condensate filtration demineralizers 6 arranged in parallel and a plurality of condensate demineralizers 10 arranged in parallel are installed downstream of the condensate pump. 9 and 11 are bypass valves, which are normally closed.

Normally, for example, during rated operation of a boiling water reactor, the steam discharged from the turbine is condensed into water in the condenser, and the
Collects in hot well 3A. With the two condensate pumps 5A and 5B in operation, water in the first hot well 3A can be sent to the condensate filtration and desalination device 7 through the flow control valve 6. The condensate pump 5c is in a standby state. The water purified in the condensate filtration demineralizer 7 is further purified in the condensate demineralizer 10, and then sent to the grand steam condenser 12 and the condenser air extractor 13.
The temperature is raised in the head tank water level control valve 18, and the second
Guided into Hotwell 3B. 2nd hot well 3B
The water inside the reactor pressure vessel (not shown) is supplied through the water supply pipe 18 into the reactor pressure vessel (not shown). Although not shown, the water supply pipe 18 includes a water supply pump and a water supply heater. 14 is a condensate head tank.

Flow rate control of the condensate pipe 4 will be explained. This flow rate control is controlled by the mask controller 16 and sub-controller 28. The master controller 16 is
An output signal from a flow meter 15 provided in the condensate pipe 4 and an important signal from a circuit breaker for the pump motor power supply indicating the driving state of the condensate pumps 5A, 5B, and 5C are input. sub·
The output signal of the master controller 16 and the output signal of the flow meter 8 provided in the condensate pipe 4 are input to the controller 28 . The mask controller 16 includes a current/voltage converter 17, a comparator 19, a proportional number integrator 20, a flow rate setting device 21, and a condensate pump state determination device 33.

The sub-controller 28 includes a current/voltage converter 29, a comparator 30, a proportional-integrator 31, and a voltage/current converter 3.
Consists of 2.

Condensate pump 5 and 5B are driven and condensate pump 5C
During normal operation when the condensate pumps 5A and 5 are on standby,
The circuit breaker of B is input, and the circuit breaker of condensate pump 5C is disconnected. The states of these circuit breakers are detected and input to the condensate pump state determination device 33 of the master controller 16. Details of the condensate pump state determination device 33 are shown in FIG. The condensate pump state determination device 33 uses a timer 24. NO
T circuit 25. AND circuits 26A, 26B, 26C.

It consists of 26D and 0 circuits 27A and 27B.

When the condensate pumps 5A and 5B are operating normally,
AND circuit 26A provides an output signal. Therefore, the relay 23a operates, and the set value of the setter 22a of the flow rate setter 21 is output to the comparator 19. The set value A is the flow rate set value of the condensate pipe 4 when the two condensate pumps are operating normally.

On the other hand, the current signal which is the output signal of the flowmeter 15 is the current -
After being converted into a voltage signal by the voltage converter 17, the comparator 19
is input. Comparator 19 outputs a deviation signal between the current signal and set value A. This deviation signal is the proportional/integrator 2
It is input to 0. The proportional/integrator 20 outputs a signal of the flow rate passing through one of the plurality of condensate ν over-demineralizers 7 arranged in parallel based on the deviation signal. The comparator 30 of the sub-controller 38 is inputted to the output signal of the flow meter 8 after being converted by the current/voltage converter 29 . Comparator 30
calculates the deviation between the output signal of the flowmeter 8 and the output signal of the proportional/integrator 20. This deviation is input to the proportional/integrator 31. The output signal of the proportional/integrator 31 controls two flow control valves via a voltage/current converter. The flow control valve 6 and the flow meter 8 are arranged on the upstream and downstream sides of each condensate ν superdemineralizer 7. A sub-controller 28 is also arranged for each condensate filtration demineralizer 7 and controls each flow control valve 6. In this way, condensate bonders 5A and 5B
is being driven, the flow rate of the condensate pipe 4 is the set value A.
adjusted to.

Next, a case will be described in which one of the condensate bonders 5A and 5B in operation, that is, the condensate pump 5A trips, and the condensate pump 5C in a standby state does not start. in this case,
When the condensate bomb A trips, the circuit breakers of the condensate bonders 5B and 5C are disconnected, so the OR circuit 27A does not output a signal, and the OR circuit 27B outputs a signal. AND
Circuit 26D receives the output signals of NOT circuit 25 and OR circuit 27B and outputs a signal. The output signal of AND circuit 26D operates relay 23Ci and also operates timer 24. After a predetermined period of time (for example, 1 hour) has elapsed, the wipeout mechanism 34 causes the timer 24 to
Cut off the output signal from circuit 26D to relay 23C, and
The output signal of the ND circuit 26D is transmitted to all relays 23b. In this way, when the condensate pump 5A trips and the condensate pump 5C does not start after that, the relay 230 operates as the condensate pump 5A trips, and after a period of time, the relay 230 becomes inactive and the relay 23b operates. Therefore, the set value C of the setter 22C is output to the comparator 19 for one hour after the condensate pump 5 A) IJ is turned on, and the set value B of the comparator 22b is output to the comparator 19 after the time elapses. Ru. The set value B is the flow rate set value of the condensate pipe 4 when only one condensate pump is being driven. The set value C is a flow rate set value of the condensate pipe 4 that is lower than the set value B in order to prevent a run gamma cloud of the condensate pump when only one condensate pump is being driven.

Changes in the flow rate in the condensate pipe 4 when one condensate pump trips during operation and when the standby condensate pump does not start up in this embodiment will be explained with reference to FIGS. 7 to 9. Flow rate setting device 21
The flow rate setting value of the condensate pipe 4 outputted from the condensate pipe 4 changes as shown by the solid line in FIG.

Condensate pump 5A)! Condensate pipe 4 for 1 hour after J tube.
Since the flow rate set value of the condensate pipe 4 is set to a lower set value C than the flow rate set value B when one condensate pump is operated, in this embodiment, the flow rate of the condensate pipe 4 is set to the set value as shown in FIG. It does not significantly exceed B and is maintained at approximately the set value B. The discharge flow rate of the five condensate pumps in operation also changes as shown by the solid line in FIG. 9, and never exceeds the runout flow rate of the condensate pump. Therefore, even when the condensate pump trips, it can be used without damaging all other condensate pumps.

When the condensate pump 5A trips while the condensate pump 5B is in operation, and the spare condensate pump 5C is activated within one hour, the relay 23 is activated when the condensate pump 5A trips.
0 operates, but as the condensate pump 5C operates, the relay 23C becomes inoperative and the relay 23a operates. Therefore, the flow rate setting value of the condensate pipe 4 temporarily becomes the setting value C, but returns to the setting value A soon. In this case as well, the risk of run-out flow rate overflow of the condensate pump 5C during the period from after the condensate pump 5A) lips to when the condensate pump 5C starts can be completely reduced.

In the above-mentioned embodiment, the relays 23a, 23b, and 23C of the mask controller 16 were operated by detecting the on state of the circuit breaker of the power supply of the entire condensate pump, but the operation was performed by the winding of the motor of each condensate pump. The measurement may be performed based on the detection of the current flowing in the wire or the voltage between the winding terminals.

The invention is also applicable to water supply systems for steam generators and boilers of other types of nuclear reactors, such as pressurized water reactors and fast breeder reactors.

According to the present invention, when a site three-type condenser is used, runout of other condensate pumps that are being driven can be prevented when the condensate pump flips.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the change in the flow rate set value of the condensate purification system piping during a pump trip in a conventional steam generator water supply system, and Figure 2 is a characteristic diagram showing the change in the flow rate set value in Figure 1. FIG. 3 is a characteristic diagram showing the change in the discharge flow rate of one condensate pump when the flow rate setting value changes in FIG. Fig. 5 is a system diagram of the vicinity of the condensate purification system piping of a water supply system for a steam generator, which is a preferred embodiment of the system. 7 is a system diagram of the condensate pump status determination device shown in FIG. is a characteristic diagram showing the flow rate change of the condensate purification system piping when the flow rate set value changes in Figure 7, and Figure 9 is the characteristic diagram of the
It is a characteristic diagram showing the change in the discharge flow rate of the 11 condensate bottles when the flow rate setting value shown in the figure changes. 1... Condenser, 3A... 1st hot well, 3B.
...Second hot well, 4...Condensate purification system piping, 5A
, 5B. 5C... Condensate pump, 6... Flow ta control valve, 7...
Condensate filtration demineralizer, 8.15...Flow meter, 11...Condensate demineralizer, 16...Master controller, 19.3
0...Comparator, 20.31...Proportional/integrator, 21
...Flow rate setting device, 28...Sub-controller, 3
3... Condensate pump status determination device.

Claims (1)

[Scope of Claims] (1) A condenser having first and second hot wells, a condensate pipe that leads water in the first hot well to the second hot well, and a plurality of condensate pipes provided in the condensate pipe. In a water supply system for a steam generator, which includes a condensate pump, a water supply pipe that supplies water in the second hotwell to the steam generator, and a water supply pump provided in the water supply pipe, a flowmeter is installed in the condensate pipe. a means for detecting the operating state of the condensate pump; a means for adjusting the flow rate in the condensate pipe;
The output signals from the flowmeter and the operating state detection means are input, and when one of the condensate pumps trips, the flow rate setting value of the condensate pipe is set to one of the condensate pumps for a predetermined period of time. a second set value lower than the operating set value, and after the predetermined time elapses, the flow rate set value of the condensate pipe is increased to the first set value, and means for controlling all of the flow rate adjusting means based on these set values. A water supply device for a steam generator, characterized in that: