JPH026793A - Auxiliary apparatus cooling device - Google Patents

Abstract

PURPOSE:To reduce the pressure of a cooling fluid of each part of an auxiliary apparatus cooling device by allowing a flow resistor to generate a flow going to a circulation piping from a surge tank. CONSTITUTION:When a surge tank circulation pump 10 is operated, a downflow is generated in a surge tank connecting piping 4, and a flow pressure loss corresponding to the opening adjustment quantity of a pressure reducing valve 5 is generated. Therefore, auxiliary apparatus cooling water pressure of each part of an auxiliary apparatus cooling device becomes lower than before the pump 10 is operated. A surge tank 1 is installed in a much higher position than an auxiliary apparatus 8 to be cooled being in the highest position so that the inside of the system is held in a state that it is filled with water, and a cooling fluid circulation pump 2 is provided on a low position in order to secure forced pressure. Therefore, an effective NPSH of this pump 2 still has a sufficient allowance, even if lowering of the auxiliary apparatus cooling water pressure is generated. Also, since the auxiliary apparatus cooling water pressure falls, the auxiliary apparatus cooling water pressure can be made lower than pressure of heavy water in a heavy water cooler 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an auxiliary equipment cooling device, and particularly to an auxiliary equipment cooling device suitable for reducing pressure within a system.

[Conventional technology]

A conventionally known auxiliary equipment cooling device is disclosed in Japanese Patent Application Laid-open No. 58-20
As described in Publication No. 2897, a surge tank is provided to absorb the expansion and contraction caused by temperature changes of system fluid (auxiliary equipment cooling water). In order to ensure the pumping pressure of the water circulation pump, it was installed at a higher position than the highest auxiliary equipment to be cooled, and was connected to the inlet of the cooling water circulation pump with piping.

Taking the example of an auxiliary equipment cooling system for a pressure tube type nuclear reactor with heavy water moderation and boiling light water cooling, in order to keep the heavy water, which is the moderator, at a constant temperature, the heavy water in the calandria tank is sent to the heavy water cooler by a heavy water circulation pump. After being cooled by the auxiliary equipment cooling water circulated by the auxiliary equipment cooling water circulation pump in the heavy water cooler,
Returned to Calandria tank again. The heavy water in this system is constantly pressurized by a heavy water surge tank with cover gas sealed above the liquid level.

[Problem to be solved by the invention]

In the event that a heat transfer tube is damaged in the heavy water cooler, if the pressure of the heavy water in the heavy water cooler is lower than the pressure of the auxiliary equipment cooling water, the auxiliary equipment cooling water, which is light water, will mix into the heavy water and the purity of the heavy water will decrease. . If the purity of heavy water falls below the specified value, the reactor's rated output cannot be maintained, so the heavy water with degraded purity must be drained, purified, and reloaded, forcing the reactor to shut down during this work. .

During normal operation, the heavy water pressure in the heavy water cooler is maintained higher than the pressure of the auxiliary equipment cooling water due to the discharge pressure of the heavy water circulation pump, but the heavy water circulation pump must be stopped during regular plant inspections. At this time, the heavy water pressure in the heavy water cooler is determined by the cover gas pressure in the heavy water surge tank, the heavy water level, and the height of the heavy water cooler.

Due to the structural design of the calandria tank, the level of the calandria tank and the pressure of the cover gas inside the calandria are set low. The pressure of the auxiliary equipment cooling water in the heavy water cooler during regular plant inspections is determined by the opening degree of the heavy water temperature control valve that limits the flow rate of the auxiliary equipment cooling water supply piping to the heavy water cooler.
As the heavy water calorific value in the calandria tank decreases, the opening becomes the minimum, and the flow pressure drop of the auxiliary equipment cooling water becomes almost zero, so the water head difference between the surge tank holding the auxiliary equipment cooling water and the heavy water cooler. It is determined by adding the atmospheric pressure to the pressure, which is approximately Q, 5 kg/cJ larger than the heavy water pressure.

In the above conventional technology, the pressure balance in the heavy water cooler when the heavy water circulation pump is stopped is not considered, and if the heavy water cooler heat transfer tube is damaged, light water will flow into the heavy water.
There was a risk that the purity of heavy water would decrease.

An object of the present invention is to maintain the heavy water pressure in the heavy water cooler higher than the auxiliary equipment cooling water pressure even when the heavy water circulation pump is stopped.

[Means to solve the problem]

The above problem is solved by an auxiliary device having a cooled part, a cooling fluid circulation pump that is connected to the auxiliary device via a circulation piping and circulates cooling fluid, and a cooling fluid circulation pump that is installed in the circulation piping and cools the cooling fluid. and a surge tank connected to the circulation pipe via a surge tank connection pipe and holding the cooling fluid, the flow resistance interposed in the surge tank connection pipe. This is achieved by an auxiliary equipment cooling device comprising: a body; and means for causing the flow resistor to cause a flow from the surge tank to the circulation pipe.

Means for causing the flow resistor to generate a flow from the surge tank toward the circulation pipe is provided in a surge tank return pipe that connects the surge tank connecting pipe on the circulation pipe side of the flow resistor and the surge tank, and in the return pipe. It may also be an auxiliary equipment cooling system equipped with a surge tank circulation pump.

Further, the means for causing the flow resistor to flow from the surge tank toward the circulation piping may be an auxiliary equipment cooling device, which is piping that connects the outlet side piping of the cooling fluid circulation pump and the surge tank, or an auxiliary equipment cooling device. The auxiliary equipment cooling device according to claim 1, wherein a second flow resistor is provided in the cooling fluid return pipe connecting the cooling fluid outlet and the cooling fluid circulation pump.

Furthermore, the above-mentioned problem is that the cooling fluid return pipe connecting the cooling fluid outlet of the auxiliary equipment and the cooling fluid circulation pump inlet is provided with a flow resistor, and the surge tank connecting pipe is connected to the flow resistor. This is also accomplished by an accessory cooling system connected to the cooling fluid return line upstream of the body.

[Effect]

A flow resistance element is provided in the surge tank connecting pipe, and a flow from the surge tank to the circulation pipe is generated in the flow resistance element, so a pressure difference is created between the upstream side and the downstream side of the flow resistance element, and the flow resistance is increased. The pressure downstream of the body is lower than it would be without flow. Since the downstream side of the flow resistor communicates with the circulation pipe, when the pressure downstream of the flow resistor decreases, the auxiliary equipment cooling fluid pressure in each part of the auxiliary equipment cooling device decreases.

The surge tank return piping that connects the surge tank connection piping on the circulation piping side of the flow resistor and the surge tank, and the surge tank circulation pump installed in the piping, are connected to the surge tank, a part of the surge tank connection piping, and the flow resistance The flow resistor forms a closed circuit with the surge tank and generates a flow in the direction from the surge tank toward the circulation piping, independent of the flow of fluid on the circulation piping side.

The piping connecting the outlet side piping of the cooling fluid circulation pump and the surge tank is a continuous piping line consisting of the piping, the cooling fluid circulation pump, the surge tank, the surge tank connecting piping, and a part of the circulation piping. At least a portion of the fluid formed and discharged from the cooling fluid circulation pump flows through this line in a direction from the surge tank, through the surge tank connecting line, and toward the circulation line. When fluid flows through the surge tank connection pipe in a direction from the surge tank to the circulation pipe, a pressure difference occurs between the upstream side and the downstream side of the flow resistance body provided in the surge tank connection pipe.

If a second flow resistor is provided in the cooling fluid return piping that connects the cooling fluid outlet of the auxiliary equipment and the cooling fluid circulation pump, the cooling fluid circulation pump can be connected from the cooling fluid outlet of the auxiliary equipment in the cooling fluid return piping to the cooling fluid circulation pump. The flow towards the second flow resistor causes a pressure difference between the upstream side and the downstream side of the second flow resistor, and the pressure on the upstream side becomes higher than that on the downstream side. In other words, the pressure in the circulation piping is reduced by the action of the flow resistor installed in the surge tank connecting pipe, but the upstream side of the second flow resistor is the downstream side of the flow resistor installed in the surge tank connecting pipe. pressure is higher than that of

In addition, a flow resistance element provided in a cooling fluid return pipe connecting a cooling fluid outlet of an auxiliary device and an inlet of a cooling fluid circulation pump is caused by a flow passing through the flow resistance element toward the cooling fluid circulation pump. Since the pressure on the downstream side of the body is lower than the pressure on the upstream side, when the surge tank connecting pipe is connected to the upstream side of the flow resistor, the pressure applied to the inlet side of the cooling fluid circulation pump by the surge tank is Although the pressure on the upstream side of the flow resistor is lower than that in the case without the flow resistor, the pressure on the upstream side of the flow resistor is maintained at a positive pressure by the head pressure of the surge tank.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIG. The auxiliary equipment cooling system shown in FIG. 1 has auxiliary equipment 8, 9, 19 having a cooled part, and is connected to the auxiliary equipment 8, 9 via a cooling fluid return pipework 5 forming a part of the circulation piping. a cooling fluid circulation pump 2, and an outlet side piping 16 of the cooling fluid circulation pump that connects the discharge side of the cooling fluid circulation pump 2 and the auxiliary equipment 8, 9.19 and forms a part of the circulation piping; A heat exchanger 3 is installed in the outlet side plumber 6 and cools the cooling fluid (auxiliary equipment cooling water) that has passed through the auxiliary equipment 8, 9.19 and is heated, and the surge tank connecting pipe 4 and a surge tank 1 connected to a cooling fluid return pipe. One of the auxiliary devices is a heavy water cooler 9, and the cooling fluid flowing into the heavy water cooler 9 is controlled by a temperature control valve 17 provided on the inlet side of the heavy water cooler 9. The water pail equipment cooling device further includes a pressure reducing valve 5 which is a flow resistor provided in the surge tank connecting pipe 4 whose upstream end is the connection part with the surge tank 1, and a surge tank connecting pipe on the downstream side of the pressure reducing valve 5. 4 and the surge tank 1, and includes a surge tank return pipe 7 in which a surge tank circulation pump 10 is interposed.

When the surge tank circulation pump 10 is operated, a downward flow (flow in the direction of outflow from the surge tank 1) is generated in the surge tank connection pipe 4, and a flow pressure loss corresponding to the opening adjustment amount of the pressure reducing valve 5 is generated. , The pressure of the auxiliary equipment cooling water in each part of the auxiliary equipment cooling system is lower than before the sajitank circulation pump was operated.

In order to keep the system full of water, the surge tank 1 is installed at a higher position than the auxiliary equipment 8 to be cooled, which is located at the highest position, and the cooling fluid circulation pump 2 is installed at a lower level to ensure the pushing pressure. Therefore, the effective NPSH of the pump 2 still has a sufficient margin with respect to the required N F SH even if the auxiliary equipment cooling water pressure decreases.

Since the auxiliary equipment cooling water pressure is reduced, it becomes possible to make the auxiliary equipment cooling water pressure lower than the pressure of heavy water in the heavy water cooler 9. Further, according to this embodiment, it is possible to depressurize the system even if the cooling water circulation pump 2 is stopped or operated.

A second embodiment will be explained with reference to FIG. The auxiliary equipment cooling device shown in FIG. 2 includes a circulation pipe consisting of an outlet side plumber 6 of a cooling fluid circulation pump 2 and a cooling fluid return plumber 5;
A surge pipe (surge tank water supply pipe) 18 that connects the outlet pipe 16 and the surge tank 1 via the flow rate adjustment valve 6 and a surge tank that connects the surge tank 1 and the cooling fluid return plumber 5 via the pressure reducing valve 5 Tank connection piping 4 is provided. Components similar to those in the first embodiment shown in FIG. 1 are given the same reference numerals and explanations are omitted.

According to this embodiment, when the cooling fluid circulation pump 2 is operated, the flow rate adjustment valve 6 and the pressure reducing valve 5 are opened, and the surge tank water flow pipe 18, the surge tank 1, the surge tank connection pipe 4, and the pressure reducing valve 5 are opened. A flow is formed that passes through in this order. This flow creates a pressure difference between the upstream and downstream sides of the pressure reducing valve 5, lowering the pressure on the downstream side, and keeping the auxiliary equipment cooling water pressure in the heavy water cooler 9 lower than the heavy water pressure during periodic inspections. becomes possible. The flow rate passing through the surge tank connection pipe 4 can be arbitrarily set by the opening degree of the flow rate adjustment valve 6.

In a heavy water-moderated, boiling, light-water-cooled pressure tube reactor, the pressure of auxiliary equipment cooling water is required to be reduced only during periodic plant inspections when the reactor is shut down, and the calorific value of heavy water at that time is almost zero; It is possible to restrict the amount of cooling water for auxiliary equipment supplied to the cooler 9 using the temperature adjustment valve 17 and pass the water to the surge tank water supply pipe 18, and to operate the pressure reducing valve 5 of the surge tank connection pipe 4. , there is no need to increase the capacity of the cooling fluid circulation pump 2.

In addition, the pressure in the cooling fluid return pipe at the outlet of the auxiliary equipment 8 located at the highest position decreases by the pressure reducing valve (pressure drop) at the pressure reducing valve 5, and the height of the return pipe and the water level in the surge tank 1 decrease. If they are the same, only this pressure reducing valve will have negative pressure, but the required pressure reduction amount is 0.5 kg/cn? In this case, the saturation pressure at the outlet of the auxiliary equipment 8 when the auxiliary equipment cooling water temperature is 40°C is 0.9 Kg/a# negative pressure, which is a sufficient margin.

FIG. 3 shows a third embodiment, in which the cooling fluid return pipe 1 of the auxiliary equipment 8 outlet is located at the highest position of the embodiment shown in FIG.
5, a negative pressure prevention valve 11 is provided as a second flow resistor.

According to this embodiment, the flow of auxiliary equipment cooling water through the negative pressure prevention valve 11 causes a pressure loss between the upper and downstream sides of the negative pressure prevention valve 11, so that the upstream side of the negative pressure prevention valve 11 has a higher pressure than the downstream side. becomes higher, and the pressure in the cooling fluid return pipe at the outlet of the auxiliary equipment 8 located at the highest position can be increased by the pressure loss of the negative pressure prevention valve 11.
Negative pressure can be reduced. If the pressure loss of the pressure reducing valve 5 and the negative pressure prevention valve 11 are the same, the negative pressure will not be generated, but the pressure loss of the negative pressure prevention valve 11 will reduce the auxiliary equipment cooling water in the cooled part of the highest position auxiliary equipment 8. This is effective when the required pressure loss in the cooled part of the highest-positioned auxiliary equipment 8 is smaller than the allowable pressure loss. Note that the downstream pressure of the negative pressure prevention valve 11 can be determined by installing the negative pressure prevention valve 1 at a position where the pressure loss of the negative pressure prevention valve 11 is lower than the height of the outlet of the auxiliary equipment 8 at the highest position. , can be kept under positive pressure.

FIG. 4 shows a fourth embodiment of the present invention, in which a cooling fluid return piping 5 is provided with a pressure reducing valve 5 as a flow resistor, and the cooling fluid return piping 15 on the upstream side of the pressure reducing valve 5 is surge-resistant. The downstream end of the tank connection pipe is connected. An auxiliary equipment cooling water pipe on the outlet side of the heavy water cooler 9 is connected to the downstream side of the pressure reducing valve 5 .

According to this embodiment, by operating the cooling fluid circulation pump 2, the surge tank water supply plumber 8 shown in FIG.
It is possible to provide the pressure reducing valve 5 with a flow in the direction toward the cooling fluid circulation pump 2 without providing the surge tank circulation pump shown in FIG. When a pressure loss of
Without providing the negative pressure prevention valve shown in FIG. 3, the auxiliary equipment cooling water pressure at the outlet of the highest position auxiliary equipment 8 is maintained at a positive pressure.

〔Effect of the invention〕

According to the auxiliary equipment cooling device according to claim 1 of the present invention, an auxiliary equipment having a part to be cooled, a cooling body circulation pump that is connected to the auxiliary equipment via a circulation pipe and circulates cooling fluid; The auxiliary equipment cooling device includes a heat exchanger that is installed in the piping and cools the cooling fluid, and a surge tank that is connected to the circulation piping via a surge tank connection piping and holds the cooling fluid. a flow resistor interposed in the surge tank connecting pipe; a means for causing the flow resistor to generate a flow from the surge tank toward the circulation pipe;
As a result, the flow from the surge tank toward the circulation piping creates a pressure difference between the top and downstream of the flow resistor, and the pressure difference is applied to each part of the auxiliary equipment cooling system without changing the water level in the surge tank. It becomes possible to reduce the pressure of the cooling fluid, which has the effect of preventing the cooling fluid from mixing with the fluid on the side of the auxiliary equipment to be cooled.

According to the auxiliary equipment cooling device according to claim 2, the means for causing the flow resistor to generate a flow from the surge tank toward the circulation pipe is connected to the surge tank connecting pipe on the circulation pipe side of the flow resistor and the surge tank. As an auxiliary equipment cooling system that includes a surge tank return pipe that connects the tank and a surge tank circulation pump installed in the return pipe, the pressure on the downstream side of the flow resistor is maintained regardless of whether the cooling fluid circulation pump is running or stopping. Since it is possible to lower the temperature on the upstream side, the same effect as in the previous section can be obtained even during regular plant inspections.

Moreover, according to the auxiliary equipment cooling device described in claim 3,
The means for causing a flow from the surge tank to the circulation piping in the flow resistor is provided as piping connecting the outlet side piping of the cooling fluid circulation pump and the surge tank, by means of a portion of the fluid discharged from the cooling fluid circulation pump. , it is possible to create a pressure difference between the top and downstream of the flow resistance body, so the pressure of the auxiliary equipment cooling fluid in each part of the auxiliary equipment cooling system can be reduced without providing a surge tank circulation pump.
The effect of preventing the cooling fluid from mixing with the fluid on the side of the cooled auxiliary equipment was obtained.

According to the auxiliary equipment cooling device according to claim 4, the second flow resistor is provided in the cooling fluid return pipe connecting the cooling fluid outlet of the auxiliary equipment and the cooling fluid circulation pump. The pressure on the upstream side of the surge tank is higher than the pressure on the downstream side of the flow resistor installed in the surge tank connection pipe, so
This allows the pressure on the cooling fluid outlet side of the auxiliary equipment located at the highest position to be maintained at a positive pressure, and has the effect of preventing the cooling fluid from vaporizing within the piping.

According to the auxiliary equipment cooling device described in claim 5, an auxiliary equipment having a part to be cooled, a cooling fluid circulation pump connected to the auxiliary equipment via a circulation piping and circulating cooling fluid, and a cooling fluid circulation pump connected to the auxiliary equipment via a circulation piping, and In the auxiliary equipment cooling device, the auxiliary equipment cooling device includes a heat exchanger that is interposed to cool the cooling fluid, and a surge tank that is connected to the circulation pipe via a surge tank connection pipe and holds the cooling fluid. A flow resistor is provided in the cooling fluid return pipe connecting the cooling fluid outlet of the cooling fluid circulation pump and the cooling fluid circulation pump inlet, and the surge tank connecting pipe is connected to the cooling fluid return pipe on the upstream side of the flow resistor. The pressure inside the piping on the cooling fluid outlet side of the auxiliary equipment connected upstream of the flow resistor is maintained at a positive pressure without installing a new flow resistor in addition to the flow resistor, and the cooling medium inside the pipe is maintained at a positive pressure. It has the effect of preventing vaporization.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a first embodiment of the present invention, Fig. 2 is a system diagram showing a second embodiment of the invention, and Fig. 3 is a system diagram showing a third embodiment of the invention. FIG. 4 is a system diagram showing a fourth embodiment of the present invention. 1. Surge tank, 2. Cooling fluid circulation pump, 3.
... Heat exchanger, 4. Surge tank connection piping, 5. Flow resistance element (pressure reducing valve), 7. Surge tank return piping, 8.
9.19・Auxiliary equipment, 10・Surge tank circulation pump, 1
1. Second flow resistor (negative pressure prevention valve), 15. Circulation piping (cooling fluid return piping), 16. Circulation piping (outlet piping of cooling fluid circulation pump), 18. Piping that connects the outlet side piping and the surge tank (surge tank water flow piping).

Claims (1)

[Scope of Claims] 1. An auxiliary device having a part to be cooled, a cooling fluid circulation pump connected to the auxiliary device via a circulation piping and circulating a cooling fluid, and a cooling fluid circulation pump installed in the piping to circulate the cooling fluid. a heat exchanger that cools the cooling fluid; a surge tank that is connected to the circulation pipe via a surge tank connection pipe and holds the cooling fluid;
An auxiliary equipment cooling device comprising: a flow resistor interposed in the surge tank connecting pipe; and means for causing the flow resistor to generate a flow from the surge tank toward the circulation pipe. An auxiliary equipment cooling device featuring: 2. The means for causing the flow resistor to flow from the surge tank toward the circulation pipe includes a surge tank return pipe that connects the surge tank to the surge tank connection pipe on the circulation pipe side of the flow resistor, and the return pipe. 2. The auxiliary equipment cooling device according to claim 1, further comprising a surge tank circulation pump provided in the auxiliary equipment cooling device. 3. The means for causing the flow resistor to flow from the surge tank toward the circulation piping is piping that connects the outlet side piping of the cooling fluid circulation pump and the surge tank. Auxiliary equipment cooling system. 4. The auxiliary equipment cooling device according to claim 1, wherein a second fluid resistance body is provided in the cooling fluid return pipe connecting the cooling fluid outlet of the auxiliary equipment and the cooling fluid circulation pump. 5. Auxiliary equipment having a cooled part, a cooling fluid circulation pump that is connected to the auxiliary equipment via circulation piping and circulates cooling fluid, and a heat exchanger that is installed in the piping and cools the cooling fluid. and a surge tank connected to the circulation pipe via a surge tank connection pipe and holding the cooling fluid;
In the auxiliary equipment cooling device, a flow resistance body is provided in the cooling fluid return pipe connecting the cooling fluid outlet of the auxiliary equipment and the cooling fluid circulation pump inlet, and the surge tank connecting pipe is connected to the An auxiliary equipment cooling device, characterized in that it is connected to the cooling fluid return piping on the upstream side of the flow resistor.