JPH04262091A - Cooling water circulating facility for re-circulating pump - Google Patents

Abstract

PURPOSE:To remove the thermal effect by the cooling water temperature to a mechanical seal and prevent the leak of the cooling water from the mechanical seal. CONSTITUTION:Temperature detectors 21, 22 are provided on the first-stage seal chamber 3a and the second-stage seal chamber 3b respectively. Temperature regulating valves 34, 36 are provided on the downstream side of the first-stage seal chamber 3a and the second-stage seal chamber 3b. Temperature signals of the temperature detectors 21, 22 are fed to the temperature regulating valves 34, 36 to regulate the temperature of the cooling water. The temperature- regulated cooling water passes a cooling water return pipe 26, a water feed pump 27 and a heat exchanger 28 from an outlet valve 25 connected to the outflow side of the regulating valves 34, 36, and flows into the first-stage seal chamber 3a and the second-stage seal chamber 3b from inflow pipes 31, 32 respectively.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling water circulation system for a recirculation pump used in a nuclear power plant for cooling a mechanical seal of a recirculation pump for circulating reactor water in a reactor pressure vessel.

0003

[Prior Art] For example, a reactor recirculation pump that efficiently circulates the primary cooling water of a light water nuclear reactor is a large-capacity pump that handles high-temperature, high-pressure pure water. It is a staged rigid centrifugal pump.

A nuclear reactor recirculation pump incorporating a conventional pump shaft sealing device will be described below with reference to FIG.

In FIG. 3, reference numeral 1 indicates an upper casing, and inside this upper casing 1 are first and second stage seal chambers 3a as seal chambers 3 for sealing the pump shaft 2.
, 3b are provided. Inside this seal chamber 3, first-stage and second-stage seal chambers 4a and 4b are provided as mechanical seals 4, surrounding the side surface of the pump shaft 2. A shaft-sealing water injection pipe 5 is provided in the upper part of the seal chamber 3, and a heat exchanger 6 is provided around the outer periphery of the seal chamber 3. The upper end of the pump shaft 2 is connected to the motor shaft 8 via a flexible joint 7.
It is connected to the. A labyrinth portion 9 is formed on the lower side surface of the pump shaft 2, and an impeller 10 is attached to the lower side of the labyrinth portion 9, which has a plurality of annular grooves stacked one on top of the other in the axial direction. The impeller 10 is arranged within a lower casing 11 that constitutes a pump chamber. The lower casing 11 has bolts 1 attached to a base 12 connected to the lower end of the upper casing 1.
3 is tightened and connected. A casing cover 14 is interposed between the base 12 and the lower casing 11. An underwater bearing 15 is attached to the lower end surface of the casing cover 14, and the underwater bearing 15 pivotally supports the shaft portion of the impeller 10. The lower casing 11 includes a suction port 16 through which reactor primary cooling water, that is, pump water (hot water) flows into the lower casing 11;
A discharge port 17 for discharging the primary cooling water sucked in by the impeller 10 from the suction port 16 is formed below. Also,
A circulation vane 18 is attached to the pump shaft 2 above the labyrinth portion 9, and the circulation vane 18 circulates the shaft sealing water in the seal chamber 3. In the figure, 19 is a flange of the upper casing 1.

As described above, the conventional pump shaft 2 is surrounded by mechanical seals 4 (4a, 4b) and an impeller 10 that functions as a pump and sucks in and discharges pump water. , an underwater bearing 15 that pivotally supports the shaft portion of the impeller 10 attached to the pump shaft 2 that rotates the impeller 10, and an underwater bearing 15 that is attached to the underwater bearing 15 to partition the upper casing 1 and the lower casing 11. It consists of a casing cover 14. In addition, mechanical seal 4
Seal chamber 3 (3a, 3b) containing (4a, 4b)
), the shaft sealing water, that is, the cold water part, and the hot water part in the pump chamber, which contains the impeller 10, underwater bearing, etc. and is filled with pump water, are connected to the circulation vane 18 attached to the pump shaft 2 and the labyrinth part. It is divided into 9. The heat exchanger 6 is equipped with a mechanical seal 4 (4
This is part of the cooling water circulation equipment for cooling the shaft sealing water to prevent damage due to temperature rise in a and 4b). The shaft water seal is for sealing the mechanical seals 4 (4a, 4b) to prevent pump water from flowing into them.

A cooling water circulation facility for circulating cooling water within the seal chambers 3a and 3b in order to cool the first stage mechanical seal 4a and the second stage mechanical seal 4b will be explained with reference to FIG.

As shown in FIG. 4, temperature detectors 2 are installed in the cooling water reservoirs 20a and 20b of the seal chambers 3a and 3b, respectively.
1 and 22 are provided, and the outflow side pipes 23 and 24 of the seal chambers 3a and 3b merge and are connected to an outlet valve 25. The outlet side of the outlet valve 25 is connected to a cooling water return pipe 26 . A water supply pump 27 and a heat exchanger 28 are connected to the outflow side of the cooling water return pipe 26. A cooling water supply pipe 29 is connected to the outflow side of the heat exchanger 28, and the cooling water supply pipe 29 is connected to the inflow pipes 31 and 31 of the seal chambers 3a and 3b via branch pipes 30.
It is connected to 32. The outflow side of the cooling water supply pipe 29 is connected to the inflow side of the other cooling load 33.
The outflow side of the cooling water return pipe 26 is connected to the cooling water return pipe 26 .

[0009] After the cooling water is sent to the heat exchanger 28 by the water supply pump 27 and controlled to a predetermined supply temperature,
The cooling load seal chambers 3a, 3b and other cooling loads 3 are supplied via the cooling water supply pipe 29, branch pipe 30, inflow pipes 31, 32.
3. After the cooling water removes heat from each load side, it flows through a closed circuit that returns to the water supply pump 27 via the cooling water return pipe 26. It is necessary to supply a flow rate of cooling water to each load that satisfies the amount of heat exchange required by each load. The setting is performed, for example, by adjusting the opening degree of a valve, such as the outlet valve 25, provided for each load. Note that the flow rate may be set using an orifice for flow rate adjustment instead of adjusting the opening degree of the valve.

0010

[Problem to be Solved by the Invention] The flow rate of cooling water to each load is set by the closed circuit of the cooling water circulation described above.
For example, the load for supplying cooling water changes depending on the operation mode, such as during normal operation, cooling, periodic inspection, and emergency. That is, since the presence or absence of cooling water supply in each operation mode differs depending on the demands of each load, the flow balance of the entire facility also changes accordingly. These are seal chambers 3a and 3b
This also leads to fluctuations in the flow rate of cooling water to each load. Therefore, when initially setting the opening degree of the valve, these flow rate fluctuations must be taken into account. In other words, specifically, from a minimum of 100% to a maximum of 100% of the required flow rate.
Set to α% (where α is the increased flow rate due to flow rate fluctuation). On the other hand, regarding the cooling water supply temperature, there are cases where this setting is lowered to the extent possible for operational reasons than the temperature determined as a setting condition, for example, 35°C.

For each load in such a system, (
1) Cooling water is supplied in excess of the required flow rate. (2) A case may occur in which the cooling water supply temperature falls below the set value. However, these are all factors that cause fluctuations on the stable side of the cooling function, and are not considered to be a problem.

However, as a result of experiments conducted in accordance with the present invention, it has been found that the seal chambers 3a and 3b have the following problems. In other words, it is not possible to maintain constant fluctuations in the temperature of the cooling water flowing to the mechanical seal.
The flow rate of cooling water increases and decreases for the seal chambers 3a and 3b. Therefore, as the flow rate increases, more cooling is performed than necessary, which results in leakage from the mechanical seal of the recirculation pump.

The present invention has been made to solve the above problems, and it maintains the cooling water at a predetermined temperature so that the temperature of the seal chamber can be kept constant, thereby reducing the thermal influence of the cooling water temperature on the mechanical seal. An object of the present invention is to provide cooling water circulation equipment for a recirculation pump that can be removed to prevent leakage of cooling water from a mechanical seal. [Structure of the invention]

[0014]

SUMMARY OF THE INVENTION The present invention has first and second stage seal chambers for cooling the first and second stage mechanical seals of a recirculation pump. In the cooling water circulation equipment of a recirculation pump that supplies and discharges cooling water to and from the cooling water reservoirs of two-stage seal chambers, a first temperature sensor is provided in the first-stage seal chamber, and a first temperature sensor is provided in the first-stage seal chamber. Connect the first temperature control valve to the side,
A second temperature sensor is provided in the second stage sealing chamber, and a second temperature control valve is connected to the outflow side of the second stage sealing chamber, and the first temperature control valve and the second temperature control valve are connected to each other. A cooling water return pipe is connected to the outflow side of the outlet valve, a water supply pump and a heat exchanger are connected to the cooling water return pipe, and a water supply pump and a heat exchanger are connected to the cooling water return pipe. A cooling water supply pipe is connected to the outflow side of the cooling water supply pipe, and the outflow side of the cooling water supply pipe is connected to the inflow sides of the first and second stage seal chambers.

[0015]

[Operation] The first and second stage mechanical seals of the recirculation pump are activated by signals from temperature detectors installed in the first and second stage seal chambers, where cooling water is collected to cool the first and second stage mechanical seals. control the temperature control valve. By supplying cooling water under constant conditions through this temperature control, no expansion or contraction occurs due to thermal effects on the mechanical seal. This can prevent leakage from the mechanical seal.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a cooling water circulation system for a recirculation pump according to the present invention will be described with reference to FIG. In addition,
In the present invention, the cooling water circulation equipment of the mechanical seal 4 is improved, and the structure of the recirculation pump is the same as that shown in FIG. 3, so a description of the mechanism of the mechanical seal 4 and the seal chambers 3a and 3b will be omitted. do.

In FIG. 1, a first temperature detector 21 is provided in the first stage sealing chamber 3a and inserted up to the cooling water reservoir 20a. Outflow side piping 23 of first stage seal chamber 3a
A first temperature adjustment valve 34 is connected to the first temperature adjustment valve 34 , and the first temperature adjustment valve 34 and the first temperature detector 21 are electrically connected by a first signal line 35 . Further, a second temperature detector 22 inserted up to the cooling water reservoir is provided in the second stage sealing chamber 3b. A second temperature adjustment valve 36 is connected to the outflow side piping 24 of the second stage seal chamber 3a, and the second temperature adjustment valve 36 and the second temperature detector 22 are connected to the second temperature adjustment valve 36.
electrically connected by the signal line. Outflow side piping 23, 2 of the first temperature adjustment valve 34 and the second temperature adjustment valve 36
4 are joined together and connected to an outlet valve 25. The outlet side of the outlet valve 25 is connected to a cooling water return pipe 26 . A water supply pump 27 and a heat exchanger 28 are connected to the cooling water return pipe 26 . A cooling water supply pipe 29 is provided on the outflow side of the heat exchanger 28.
is connected. A branch pipe 30 and another cooling load 33 are connected in parallel to the cooling water supply pipe 29 . Inflow pipes 31 and 32 are connected to the branch pipe 30, and the inflow pipes 31 and 32 are connected to the first stage and second stage seal chambers 3a and 3b, respectively. The outflow side of the other cooling load 33 is connected to the cooling water return pipe 26 and then to the water supply pump 27, forming a closed circuit.

[0018] However, in the first embodiment, the first
The temperature adjustment valve 34 and the second temperature adjustment valve 36 automatically adjust the opening degree according to the temperature state of each seal chamber 3a, 3b measured by the first temperature detector 21 and the second temperature detector 22, respectively. It is something to control. The first stage seal chamber 3a and The temperature state of the second stage sealing chamber 3b can be kept constant at a certain set value. As a result, the possibility of leakage due to overcooling of the mechanical seal of the recirculation pump is reduced, and reliability can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that the same parts in FIG. 2 as those in FIG. This second embodiment differs from the first embodiment in that the outlet valve 25 is installed outside the reactor containment vessel 38.

According to this second embodiment, the opening degree of the outlet valve 25 can be adjusted in the event of an event such as failure of the first and second temperature regulating valves 34, 36 during normal operation, and the opening degree of the outlet valve 25 can be adjusted. Reliability can be further improved through adjustment.

[0021]

Effects of the Invention According to the present invention, the reactor auxiliary cooling system (RC
It is possible to remove supercooling caused by fluctuations in the flow balance on the W) side and supply cooling water under constant conditions to the seal chamber. This prevents the mechanical seal from expanding or contracting due to thermal effects, thereby preventing leakage from the mechanical seal. Furthermore, by providing an outlet valve connected to the downstream side of the temperature control valve outside the reactor containment vessel, redundancy can be provided in the event of an event such as a failure of the temperature control valve.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a first embodiment of cooling water circulation equipment for a recirculation pump according to the present invention.

FIG. 2 is a system diagram showing a second embodiment of the cooling water circulation equipment for the recirculation pump according to the present invention.

FIG. 3 is a longitudinal sectional view showing a recirculation pump.

FIG. 4 is a system diagram showing cooling water circulation equipment for a conventional recirculation pump.

[Explanation of symbols]

1... Upper casing, 2... Pump shaft, 3 (3a, 3b)
... Seal chamber, 4 (4a, 4b) ... Mechanical seal, 5
...Shaft seal water injection pipe, 6...Heat exchanger, 7...Flexible joint, 8...
Motor shaft, 9... Labyrinth part, 10... Impeller, 11... Lower casing, 12... Base, 13... Bolt, 14... Casing cover, 15... Underwater bearing, 16... Suction port, 17
...Discharge port, 18...Circulation vane, 19...Upper flange, 20
a, 20b...Cooling water reservoir, 21, 22...Temperature detector, 2
3, 24... Outlet side piping, 25... Outlet valve, 26... Cooling water return pipe, 27... Water supply pump, 28... Heat exchanger, 29... Cooling water supply piping, 30... Branch pipe, 31, 32... Inflow pipe , 33
...Other cooling loads, 34, 36...Temperature adjustment valve, 35, 37...
Signal line, 38...Reactor containment vessel.

Claims (1)

[Claims] 1. A recirculation pump has first and second stage seal chambers for cooling the first and second stage mechanical seals, and cooling water in the first and second stage seal chambers is provided. In the cooling water circulation equipment for a recirculation pump that supplies and discharges cooling water to and from the reservoirs, a first temperature sensor is provided in the first stage seal chamber, and a first temperature controller is provided on the outflow side of the first stage seal chamber. A second temperature sensor is provided in the second stage seal chamber, and a second temperature control valve is connected to the outflow side of the second stage seal chamber, and the first temperature control valve and the An outlet valve is provided on the outflow side of the second temperature control valve, a cooling water return pipe is connected to the outflow side of the outlet valve, and a water supply pump and a heat exchanger are connected to the cooling water return pipe. , a cooling water supply pipe is connected to the outflow side of the heat exchanger, and the outflow side of the cooling water supply pipe is connected to the inflow sides of the first and second stage seal chambers. Cooling water circulation equipment for circulation pump.