JPH11190797A - Shaft sealing water feed device of feed water pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a shaft sealing water pressure increasing pump in accordance with the operation condition of a reactor feed water pump, supply proper shaft sealing water to the shaft sealing device of the reactor feed water pump, and contrive wear reduction and power saving of the shaft sealing water pressure increasing pump. SOLUTION: A condensate pump 1 and the shaft sealing device of a reactor feed water pump 2 are connected by discharge tubing 5 and a shaft sealing water supply line 9. A stop valve 13, a shaft sealing pressure increasing pump 14, an electrically operated valve 15 and a flow control valve 16 are provided in a shaft sealing water supply line 9. A bypass line 17 having a check valve 18 is connected between the inlet side of the stop valve 13 and the outlet side of the electrically operated valve 15. A temperature controller 11 is provided on a condensate recovery line 11 connected to the drain side of the shaft sealing device 10, and the temperature controller 11 and the flow control valve 16 are electrically connected by a signal line 20. The flow control valve 16, the shaft sealing pressure increasing pump 14 and the electrically operated valve are electrically connected by a signal line 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply pump shaft sealing water supply device for a power plant.

[0002]

2. Description of the Related Art A number of fixed bush systems have been adopted as shaft sealing systems for water supply pumps. In this fixed bush system, in order to reduce the temperature of condensate leaking outside through the gap between the feed pump shaft and the fixed bush,
A shaft sealing water supply device for supplying low-temperature shaft sealing water to an intermediate portion of the shaft sealing portion is provided.

In this shaft seal water supply device, condensed water is usually taken out from a discharge pipe of a condensate pump, and the condensed water is pressurized and injected by a booster pump to secure an injection pressure required by the shaft seal device of the water supply pump. The amount of water sealed in the shaft is generally controlled by detecting the drain temperature leaking from the shaft sealing device to the outside and installing a flow control valve in the shaft sealing water supply line to control this value to a constant value. Have been.

[0004]

In the above-mentioned shaft sealing water supply device, the amount of shaft sealing water required for the water supply pump greatly varies due to a change in the clearance of the fixed bush, a change in the plant output, and the like. When the clearance of the shaft sealing device is widened due to aging, the amount of external leakage of the high-temperature pump internal water increases, so that the amount of cooling water injected into the shaft sealing device to suppress the rise in drain temperature also increases.

Further, when the plant output is low, such as in-service of the water supply pump, the suction pressure of the water supply pump becomes higher than at the rated output, so that the pressure difference between the inside and outside of the shaft sealing device becomes large, and the outside of the water contained in the pump becomes large. The leak amount increases.
Therefore, also in this case, the amount of cooling water injected into the shaft sealing device also increases in order to suppress a rise in drain temperature.

Further, in many cases, the water supply pump is provided with a threaded groove on the shaft side of the shaft sealing device so as to push back the flow of the leak from the inside of the pump to the outside by a screw effect of rotating the shaft. In this case, the injection amount tends to be larger during the stop of the pump than during the operation.

[0007] For the above-mentioned reason, the required amount of shaft sealing generally varies several times between the maximum value and the minimum value. As a matter of course, the design of the shaft sealing water supply device is designed so that the maximum required amount can be flown. Therefore, when the required flow rate is small, the flow control valve is operated in a considerably narrowed state.

Further, in this state, the shaft sealing water pressure boosting pump also continues the low flow rate operation. As a result, the body of the flow control valve is damaged by erosion, and in the case of the shaft sealing water booster pump, the impeller is damaged due to fatigue of each part and cavitation due to increase in vibration.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to control a shaft sealing water boosting pump in accordance with the operation of a reactor water supply pump to supply proper shaft sealing water.
It is an object of the present invention to provide a water supply pump shaft sealing water supply device capable of reducing wear and power of the shaft sealing water booster pump.

[0010]

According to the present invention, there is provided a water supply line for supplying water from a condensate pump to a water supply pump through a discharge pipe and a water supply heater, and a shaft sealing device for the water supply pump branched from the discharge pipe. A shaft sealing water supply line for supplying shaft sealing water to the shaft sealing water supply device, and a line for collecting condensate flowing out of the shaft sealing device, wherein a stop valve is provided on the shaft sealing water supply line. , A shaft sealing water booster pump, an electric valve and a flow control valve are connected in series, a bypass line having a check valve is connected to an inlet side of the stop valve and an outlet side of the electric valve, and a temperature is connected to the condensate recovery line. A controller is provided, the temperature controller is electrically connected to the flow control valve, and the flow control valve is electrically connected to the shaft sealing water boosting pump and the electric valve.

That is, in a shaft sealing water supply device for a water supply pump for a power plant, which includes a shaft sealing water boosting pump and a flow control valve, the shaft sealing water is supplied under a condition that the flow control valve is below a specified opening. It has an interlock to stop the water pressure pump.

According to the present invention, the state in which the opening of the flow control valve is excessively narrowed is detected, and the shaft sealing water boosting pump is automatically stopped. Low flow operation of the pump can be avoided.

According to a second aspect of the present invention, the discharge pipe of the condensate pump and the water supply line to the water supply pump are directly connected by a tie line having a differential pressure gauge. The valve is electrically connected. That is, it has an interlock that monitors the differential pressure between the condensate pump discharge pressure and the feedwater pump suction pressure and automatically stops the shaft sealing water booster pump when the differential pressure exceeds a certain set value.

According to this invention, the condition that the pressure increase by the shaft sealing water boosting pump becomes unnecessary is detected by the differential pressure between the discharge of the condensate pump and the suction of the feed water pump, and the shaft sealing water boosting pump is automatically stopped. In addition, it is possible to avoid over-throttling of the temperature control valve and low flow rate operation of the shaft sealing water booster pump.

According to a third aspect of the present invention, the shaft-sealed water boosting pump and the electric valve are electrically connected to an operating condition setting device. That is, an interlock is provided to stop the shaft sealed water booster pump under the condition that the power generation plant output becomes 100%.

According to the present invention, the condition that the boosting by the shaft sealing water boosting pump is not required is determined based on the plant output.
By monitoring the operation state of the plant and automatically stopping the shaft sealing water boosting pump, it is possible to avoid excessive throttling of the temperature control valve and low flow rate operation of the shaft sealing water boosting pump.

According to a fourth aspect of the present invention, the shaft-sealed water boosting pump and the electric valve are electrically connected to the water supply pump. That is, it has an interlock that stops the shaft sealed water boosting pump in response to the condition that the water supply pump is started.

According to the present invention, the condition that the pressure increase by the shaft sealing water boosting pump becomes unnecessary is determined based on the operation / stop condition of the feed water pump, and the shaft sealing water boosting pump is automatically stopped to thereby reduce the flow rate. Over-throttling of the control valve and low flow rate operation of the shaft sealing water booster pump can be avoided.

According to a fifth aspect of the present invention, the stop valve, the shaft sealing water booster pump, and the motor-operated valve are provided with a plurality of stop valves, shaft seal water booster pumps, and motor-operated valves connected in series to the shaft sealing water supply line. It is characterized by being connected in parallel.

That is, the required supply amount is covered by a plurality of small capacity boosting pumps installed in parallel, and the condition that the boosting by the shaft sealing water boosting pump is not necessary is determined by the differential pressure between the discharge of the condensate pump and the suction pressure of the feedwater pump. It has an interlock that detects and automatically stops the shaft sealed water booster pump one by one.

According to the present invention, by reducing the number of operating shaft-sealed water boosting pumps in stages, it is possible to avoid excessively throttling of the flow control valve and low-speed operation of the shaft-sealed water boosting pump.

According to a sixth aspect of the present invention, a cooler front valve, a cooler, and a cooler rear valve are connected to the shaft sealing water supply line, and an electric valve is provided on an inlet side of the cooler front valve and an outlet side of the cooler rear valve. A cooler bypass valve is connected, and the cooler pre-valve, the cooler post-valve, and the motor-operated valve are each electrically connected to the flow control valve.

That is, a cooler for cooling the shaft sealing water and a pipe for bypassing the cooler are arranged, and under the condition that the flow rate control valve is equal to or larger than the specified opening, the flow of the shaft sealing water is changed from the bypass side to the cooler side. By switching automatically,
The cooled shaft sealing water is supplied to a water supply pump.

According to the present invention, when a large amount of shaft sealing water is required, the required amount can be reduced by cooling the shaft sealing water, and as a result, the fluctuation range of the required shaft sealing water amount can be suppressed. Can be. Therefore, it is possible to reduce the capacity of the flow rate control valve and the shaft sealing water boosting pump, and it is possible to avoid the throttle of the flow rate control valve and the low flow rate operation of the shaft sealing water boosting pump.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a shaft seal water supply device for a water supply pump according to the present invention will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a condensate pump, which is connected to the outlet side of a turbine condenser (not shown) and flows out of the condensate. Numeral 2 is a reactor water supply pump for supplying cooling water to the reactor 3 through a water supply pipe 4.
A discharge pipe 5, a condensate purification system pipe 6, a feed water heater 7 and a feed water line 8 are sequentially connected between the condensate pump 1 and the reactor feed pump 2.

The water is supplied to a shaft sealing water supply line 9 by branching to a discharge pipe 5.
Is connected, and the other end of the shaft sealing water supply line 9 is connected to a shaft sealing device 10 of the reactor water supply pump 2. The drain side of the shaft sealing device 10 is connected to the condensate collection line 11, and the condensate collection line
A condensate recovery tank 12 is connected to 11. The bearing device 10 is attached to the reactor water supply pump 2 and has a structure for cooling by flowing condensed water.

In the shaft sealing water supply line 9, a stop valve 13, a shaft sealing water boosting pump 14, an electric valve 15, and a flow control valve 16 are sequentially connected in series. A bypass line 17 is connected to the shaft sealing water supply line 9 on the inlet side of the stop valve 13 and on the outlet side of the electric valve 15, and a check valve 18 is provided in the bypass line 17. The condensate recovery line 11 is provided with a temperature controller 19, and the temperature controller 19 is electrically connected to the flow control valve 16 by a signal line 20, and the flow control valve 16, the shaft sealing water booster pump 14, and the electric valve 15 are provided. Are electrically connected by a signal line 21.

Generally, the shaft water supply system for the reactor water supply pump takes out condensate from the discharge pipe 5 of the water condensate pump 1 and secures the injection pressure required by the shaft sealing device 10 of the water supply pump 2. Pressure injection is performed by the shaft sealing water pressure increasing pump 14. The flow rate of the shaft sealing water is detected by a temperature controller 19 which detects the drain temperature from the shaft sealing device 10, and is controlled by a flow rate control valve 16 so that this value becomes constant.

After the plant feeds the reactor feed pump 2 near 25% output or 50% output, the opening of the flow control valve 16 changes in the throttle direction as the plant output increases. In addition, immediately after the fixed bush of the reactor water supply pump 2 is replaced with the rated output of the plant, the throttle amount of the flow control valve 16 tends to increase.

Therefore, a bypass line 17 is connected to the shaft sealing water supply line 9, and a check valve 18 is provided in the bypass line 17. Further, an interlock for automatically controlling the start / stop of the shaft sealing water boosting pump 14 based on a valve opening signal from the temperature controller 19 is provided.

According to the present embodiment, when the flow control valve 16 has an opening smaller than the normal control range, the shaft sealing water boosting pump 2 is automatically stopped and the bypass line 17 is operated. Is possible.

Accordingly, the differential pressure of the throttle of the flow control valve 16 can be reduced by the pressure of the shaft sealing water booster pump 14. That is, the stop of the shaft sealing water pump 14 shifts the opening of the flow control valve 16 in the opening direction, so that control in an appropriate range becomes possible.

Further, since the shaft sealing water boosting pump 14 stops, the valve body is damaged by erosion due to the continuation of the low flow rate operation and the vibration of the shaft sealing water boosting pump 14 is increased. Can avoid the problem of damage.

Next, a second embodiment of a shaft sealing water supply device for a water supply pump according to a second aspect of the present invention will be described with reference to FIG. In FIG. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description of the overlapping parts will be omitted.

The present embodiment is different from the first embodiment in that a tie line 22 for directly connecting the discharge pipe 5 of the condensate pump 1 and the water supply line 8 to the reactor water supply pump 2 is provided.
The tie line 22 is provided with a differential pressure gauge 23, and the differential pressure gauge 23 is electrically connected to the shaft sealing water boosting pump 14 and the electric valve 15 by a signal line 24.

That is, the differential pressure gauge 23 is installed between the discharge pressure of the condensing pump 1 and the suction pressure of the reactor water supply pump 2. Since the feedwater heater 7 and the like are installed between the condensate pump 1 and the reactor feedwater pump 2, the discharge pressure of the condensate pump 1 and the suction pressure of the reactor feedwater pump 2 fluctuate according to the plant output. . An interlock is provided for automatically controlling the start / stop of the shaft sealing water boosting pump 14 upon receiving a signal indicating that the differential pressure gauge 23 has exceeded a certain set value in the process of the plant becoming rated operation.

According to the present embodiment, when the differential pressure gauge 23 exceeds a certain set value, it is possible to automatically stop the shaft sealed water boosting pump 14 and operate the bypass line 17. In accordance therewith, the differential pressure of the throttle of the flow rate control valve 16 can be reduced by the pressure of the shaft sealing water pump 14.

That is, the opening of the flow rate control valve 16 shifts in the opening direction by stopping the shaft sealing water pressure increasing pump 14, so that control in an appropriate range becomes possible. Further, since the shaft sealing water pump 14 is stopped, the valve body is damaged by erosion due to the continuation of the low flow rate operation, and the shaft sealing water pump 14 is stopped.
It is possible to avoid the problem of impeller damage due to fatigue and cavitation of various parts due to increase in vibration of the impeller.

Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 3, FIG.
The same parts as those described above are denoted by the same reference numerals and the description of the overlapping parts will be omitted.

The present embodiment is different from the first embodiment in that the shaft sealing water boosting pump 14 and the motor-operated valve 15 use
Operating condition setting equipment set to be 00% operating condition
That is, the signal line 26 is electrically connected to the signal line 25.
An interlock is provided to automatically control the start / stop of the shaft sealed water booster pump 14 under the condition that the plant output, such as the feedwater flow rate, becomes 100% operation.

According to the present embodiment, the plant is 100%
The shaft sealing water booster pump 14
Can be automatically stopped and the operation of the bypass line 17 can be performed. In accordance therewith, the differential pressure of the throttle of the flow rate control valve 16 can be reduced by the pressure of the shaft sealing water pump 14. In other words, the stop of the shaft sealing water pump 14 shifts the opening of the flow control valve 16 in the opening direction, so that control in an appropriate range becomes possible.

Further, since the shaft sealing water booster pump 14 stops, the valve body is damaged by erosion due to the continuation of the low flow rate operation and the vibration of the shaft sealing water booster pump 14 is increased. Can avoid the problem of damage.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In FIG. 4, FIG.
The same parts as those described above are denoted by the same reference numerals and the description of the overlapping parts will be omitted.

The present embodiment is different from the first embodiment in that the reactor water supply pump 2 is electrically connected to the shaft sealing water boosting pump 14 and the motor-operated valve 15 by a signal line 27. That is, an interlock for automatically stopping the shaft sealing water boosting pump 14 in response to a start / stop signal of the reactor water supply pump 2 is provided.

According to the present embodiment, upon receiving the start signal of the reactor water supply pump 2, the shaft sealed water pressure boosting pump 14 can be automatically stopped and the bypass line 17 can be operated. is there. In accordance therewith, the differential pressure of the throttle of the flow rate control valve 16 can be reduced by the pressure of the shaft sealing water pump 14.

In other words, the stop of the shaft sealing water pump 14 shifts the opening of the flow control valve 16 in the opening direction, so that control in an appropriate range becomes possible. Further, since the shaft sealing water pump 14 is stopped, the valve body is damaged by erosion due to the continuation of the low flow rate operation, and the shaft sealing water pump 14 is stopped.
The problem of impeller damage due to fatigue and cavitation of various parts due to the increase in vibration of the impeller can be avoided.

Next, a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 5, FIG.
The same parts as those described above are denoted by the same reference numerals and the description of the overlapping parts will be omitted.

This embodiment is different from the second embodiment in that a plurality of shaft-sealing water boosting pumps 15 are installed in parallel. However, for ease of explanation, the second shaft-sealing water boosting pump 14a is used. Are described in connection with an example in which are connected in parallel.

In FIG. 2, reference numeral 13a is a second stop valve, and 15a is a second electric valve, which is connected before and after a second shaft sealing water boosting pump 14a. The second shaft sealing water pressure increasing pump 14a and the second electric valve 15a are electrically connected to a differential pressure gauge 23 by a signal line 28.

Here, since the feed water heater 7 and the like are installed between the condensate pump 1 and the reactor feed pump 2, the discharge pressure of the condensate pump 1 and the suction pressure of the reactor feed pump 2 are reduced by the plant pressure. It fluctuates according to the output. In the course of the plant being in rated operation, an interferometer for controlling the start / stop of the first shaft-sealed water boosting pump 14 and the second shaft-sealed water boosting pump 14a by a signal indicating that the differential pressure gauge 23 has exceeded a certain set value. Provide a lock.

According to the present embodiment, when the differential pressure gauge 23 exceeds a certain set value, the first shaft sealed water pressure increasing pump 14 is automatically stopped. Further, when it becomes equal to or more than another set value, the second shaft-sealed water boosting pump 14a is automatically stopped,
It is possible to operate the bypass line 17.

Accordingly, the pressure difference between the throttle of the flow control valve 16 can be reduced by the pressure of the first and second shaft sealing water boosting pumps 14 and 14a. That is, the opening degree of the flow control valve 16 shifts in the opening direction in response to the stop of the first and second shaft-sealed water boosting pumps 14 and 14a, so that control in an appropriate range becomes possible.

In addition, first and second shaft sealed water boosting pumps
Since the pumps 14 and 14a are stopped, the valve body is damaged by erosion due to the continuation of the low flow rate operation, and fatigue and cavitation of various parts are caused by the increase in vibration of the first and second shaft sealing water boosting pumps 14 and 14a. The problem of impeller damage can be avoided.

Next, a sixth embodiment of the present invention will be described with reference to FIG. In FIG. 6, FIG.
The same parts as those described above are denoted by the same reference numerals and the description of the overlapping parts will be omitted.

This embodiment is different from the first embodiment in that the cooler front valve 28, the cooler 29 and the cooler rear valve 30 are connected in series to the shaft sealing water supply line 9 up to the inlet side of the stop valve 13, and the cooler An electric valve 31 is provided on the inlet side of the front valve 28 and the outlet side of the rear valve 30 after the cooler.
That is, the cooler bypass line 32 having the check valve 18 is provided, and the bypass line 17 having the check valve 18 is eliminated.

That is, in this embodiment, a cooler 29 is installed in the shaft sealing water supply line 9, and a cooler bypass line 32 having an electric valve 31 is installed in the cooler 29. The cooler front valve 28, the cooler rear valve 30 and the electric valve 31 are connected to the flow control valve 16
Are electrically connected to each other by a signal line 33.

According to the present embodiment, the flow of the shaft sealing water is automatically switched from the bypass 32 to the cooler 29 in response to the condition that the flow control valve 16 has become equal to or larger than the specified opening.
The cooled shaft seal water can be supplied to the reactor water supply pump. Thus, when a large amount of shaft sealing water is required, the required amount of shaft sealing water can be reduced by cooling the shaft sealing water, and as a result, the fluctuation range of the required shaft sealing water amount can be suppressed.

Accordingly, it is possible to reduce the capacities of the flow control valve 16 and the shaft sealing water boosting pump 14, and to avoid excessively restricting the flow control valve 16 and avoid a low flow rate operation of the shaft sealing water boosting pump 14. it can.

[0059]

According to the present invention, the flow rate control valve is controlled within an appropriate range by stopping the shaft sealing water boosting pump or cooling the temperature of the shaft sealing water in accordance with the operation state of the water supply pump. Thus, damage such as erosion of the valve element due to excessive throttling can be avoided.

Further, by stopping the shaft sealing water boosting pump, the shaft sealing water boosting pump is freed from the concerns of vibration, cavitation operation, and the like, and the driving power of the shaft sealing water boosting pump can be saved, thereby increasing the plant efficiency. Can be expected.

[Brief description of the drawings]

FIG. 1 is a piping system diagram showing a first embodiment of a shaft sealing water supply device for a water supply pump according to the present invention.

FIG. 2 is a piping system diagram showing a second embodiment of a shaft sealing water supply device for a water supply pump according to the present invention.

FIG. 3 is a piping diagram showing a third embodiment of a shaft sealing water supply device for a water supply pump according to the present invention.

FIG. 4 is a piping system diagram showing a fourth embodiment of a shaft sealing water supply device for a water supply pump according to the present invention.

FIG. 5 is a piping system diagram showing a fifth embodiment of a shaft sealing water supply device for a water supply pump according to the present invention.

FIG. 6 is a piping system diagram showing a sixth embodiment of a shaft sealing water supply device for a water supply pump according to the present invention.

[Explanation of Signs] 1. Condenser pump, 2. Reactor feed pump, 3. Reactor,
4: water supply pipe, 5: discharge pipe, 6: condensate purification system pipe, 7 ...
Feed water heater, 8 ... water supply line, 9 ... shaft sealing water supply line,
10 ... shaft sealing device, 11 ... condensate recovery line, 12 ... condensate recovery tank, 13 ... stop valve, 14 ... shaft seal water booster pump, 15 ... electric valve,
16 ... flow control valve, 17 ... bypass line, 18 ... check valve, 19
… Temperature controller, 20, 21… Signal line, 22… Tie line, 23… Differential pressure gauge, 24… Signal line, 25… Operating condition setting equipment, 26,27… Signal line, 28… Cooler front valve, 29… Cooler, 30 ... cooler valve, 31 ... electric valve, 32 ... cooler bypass line, 33 ... signal line.

Claims (6)

[Claims] 1. A water supply line for supplying water from a condensate pump to a water supply pump through a discharge pipe and a water supply heater, and a shaft sealing water supply branching from the discharge pipe and supplying shaft sealing water to a shaft sealing device of the water supply pump. In a shaft sealing water supply device for a water supply pump, comprising a line and a line for collecting condensate flowing out of the shaft sealing device, a stop valve, a shaft sealing water booster pump, an electric valve, and a flow rate in the shaft sealing water supply line. A control valve is connected in series, a bypass line having a check valve is connected to an inlet side of the stop valve and an outlet side of the motor-operated valve, and a temperature controller is provided in the condensate recovery line. A valve for supplying water to a shaft of a water supply pump, wherein the valve is electrically connected, and the flow rate control valve is electrically connected to the shaft sealing water booster pump and the electric valve. 2. A discharge line of the condensate pump and a water supply line to the feed water pump are directly connected by a tie line having a differential pressure gauge, and the differential pressure gauge, the shaft sealing water boosting pump, and the electric valve are electrically connected. 2. The connection according to claim 1, wherein
A shaft sealing water supply device for a water supply pump as described in the above. 3. The water-sealing water supply device for a water supply pump according to claim 1, wherein the shaft-sealing water boosting pump and the electric valve are electrically connected to an operating condition setting device. 4. The water-sealing water supply device for a water-supply pump according to claim 1, wherein the shaft-sealing water boosting pump and the electric valve are electrically connected to the water-feed pump. 5. A stop valve similar to the stop valve, the shaft sealing water boosting pump and the electric valve connected in series to the shaft sealing water supply line, and a plurality of shaft sealing water booster pumps and an electric valve connected in parallel. The shaft sealing water supply device for a water supply pump according to claim 2, characterized in that: 6. A cooler front valve, a cooler, and a cooler rear valve are connected to the shaft sealing water supply line, and a cooler bypass valve having an electric valve is connected to an inlet side of the cooler front valve and an outlet side of the cooler rear valve. The water supply pump shaft sealing water supply device according to claim 1, wherein the cooler front valve, the cooler rear valve, and the motor-operated valve are each electrically connected to the flow rate control valve.