Water pump shaft seal water pressure reducing device

Abstract

The present invention relates to a decompression device for the shaft seal water of a water pump, comprising: a water supply pipeline connected between a drinking water system and the shaft seal water chamber of the water pump for supplying water to the shaft seal water chamber, and a first control valve and a second control valve are provided on the water supply pipeline; a pressure stabilizing pipeline is arranged in parallel with the second control valve on the water supply pipeline and includes a decompression mechanism for automatically adjusting the opening according to the leakage water flow of the pump packing. When the water supply pressure to the shaft seal water chamber is relatively high, the pressure stabilizing pipeline can adjust the water supply pressure to the shaft seal water chamber so that the water supply pressure to the shaft seal water chamber meets the requirements of the shaft seal.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power, and more specifically, to a water pump shaft seal water pressure reducing device. Background Art

[0002] The important service water pumps of nuclear-grade equipment are responsible for providing driving force for the seawater cooling water of the important service water system (SEC) of the nuclear island, and transferring the heat load of each heat exchanger in the nuclear island to the seawater through the important service water system (SEC). If all the important service water pumps are shut down, the heat transferred by the nuclear island equipment cooling water system cannot be transferred to the seawater, and the nuclear island loses the ultimate heat sink. The unit needs to immediately withdraw and execute the accident procedure. Therefore, the important service water pumps of nuclear-grade equipment are one of the core key equipment for the cold source of the nuclear island.

[0003] The important service water pumps include vertical single-stage single-suction cantilever centrifugal pumps, and the pump shaft seal adopts packing seal. The shaft seal water is supplied by the drinking water system (SEP). After the pump shaft seal water enters the shaft seal water chamber, it is divided into two paths. One path flows downward to lubricate and cool the pump bearing and enters the pump chamber, and the other path flows upward through the packing ring and packing to lubricate and cool the pump shaft. The leakage water is discharged outdoors by the pump of the important pump house power station sewage system (SEO).

[0004] The shaft seal leakage of the SEC pump will show an abnormally large phenomenon. After the shaft seal leakage is abnormally large, it is necessary to frequently tighten the packing on-site to reduce the leakage. After a full inspection of the SEC pump group, problems such as wear of the packing shaft sleeve and wear at the bottom of the pump cover packing box are found. The maximum wear depth of the pump cover is 5 mm, and the maximum wear depth of the shaft sleeve is 4 mm. The root cause analysis shows that the shaft seal water pressure is on the high side. The shaft seal water pressure required by the SEC pump does not match the pipe network pressure of the SEP water supply system. The SEC system manual and the SEC pump maintenance manual require the shaft seal water pressure to be 2 - 4 bar.g, while the actual pressure of the on-site pump shaft seal water supply system is about 8 bar.g, which is much greater than the pressure required by the upstream document.

[0005] Therefore, it is necessary to conduct in-depth research on the pump shaft seal structure and the shaft seal water supply system, analyze the reasons for abnormal shaft seal leakage, wear of the pump cover and shaft sleeve, and seek a complete solution from the design. Reduce the pressure of the shaft seal water of the important service water pump, and at the same time ensure the long-term safe, stable and reliable operation of the important service water pump. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a water pump shaft seal water pressure reducing device in view of the above-mentioned defects of the prior art.

[0007] The technical solution adopted by the present invention to solve its technical problems is: to construct a water pump shaft seal water pressure reducing device, including:

[0008] A water supply pipeline is connected between a drinking water system and a shaft seal water chamber of a water pump for supplying water to the shaft seal water chamber. A first control valve and a second control valve are provided on the water supply pipeline.

[0009] A pressure stabilizing pipeline is arranged in parallel with the second control valve on the water supply pipeline and includes a pressure reducing mechanism for automatically adjusting the opening degree according to the leakage water flow of the pump packing.

[0010] In some embodiments, the pressure stabilizing pipeline includes a bypass pipeline arranged in parallel with the second control valve on the water supply pipeline.

[0011] The pressure reducing mechanism includes a third control valve arranged in the bypass pipeline.

[0012] In some embodiments, the third control valve is a pressure reducing valve. The pressure reducing mechanism further includes a pressure dividing pipeline connected to the pressure stabilizing pipeline and a fourth control valve arranged on the pressure dividing pipeline. The pressure dividing pipeline is connected to the downstream of the third control valve on the bypass pipeline.

[0013] In some embodiments, the fourth control valve is a regulating valve.

[0014] In some embodiments, the regulating valve is a cut-off type regulating valve.

[0015] In some embodiments, the first control valve and the second control valve are isolation valves.

[0016] In some embodiments, fifth control valve and a sixth control valve are further provided on the bypass pipeline, which are respectively located upstream and downstream of the third control valve.

[0017] In some embodiments, the fifth control valve and the sixth control valve are isolation valves respectively.

[0018] In some embodiments, the first control valve, the second control valve, the fifth control valve and the sixth control valve are all cut-off type isolation valves.

[0019] In some embodiments, a pressure detection mechanism is provided on the water supply pipeline between the first control valve and the pressure stabilizing pipeline.

[0020] Implementing the water pump shaft seal water pressure reducing device of the present invention has the following beneficial effects: When the water supply pressure to the shaft seal water chamber is relatively large, the pressure stabilizing pipeline can adjust the water supply pressure to the shaft seal water chamber to make the water supply pressure to the shaft seal water chamber meet the requirements of the shaft seal. Brief Description of the Drawings

[0021] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0022] Figure 1It is a schematic structural diagram of the water pump shaft seal water pressure reduction device and the water pump in the embodiment of the present invention. Detailed implementation manners

[0023] For a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed implementation manners of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] As Figure 1 shown, the water pump shaft seal water pressure reduction device in a preferred embodiment of the present invention includes a water supply pipeline 1 and a pressure stabilizing pipeline 2.

[0025] The water supply pipeline 1 is connected between the drinking water system and the shaft seal water chamber 31 of the water pump 3, and is used to supply water to the shaft seal water chamber 31. After the pump shaft seal water enters the shaft seal water chamber 31, it is divided into two paths. One path lubricates and cools the pump bearing and enters the pump chamber. The other path passes through the stuffing box ring and stuffing seal to lubricate and cool the pump shaft. The packing leakage water is discharged outdoors through the sewage system pump of the important pump house power station. The allowable leakage rate of the pump stuffing seal is 10 - 300 L / h, and the flow rate of the pump seal flushing water shall not be less than 500 L / h.

[0026] The water supply pipeline 1 is provided with a first control valve 11 and a second control valve 12, which can respectively control the on-off of the position on the water supply pipeline 1.

[0027] The pressure stabilizing pipeline 2 is arranged in parallel with the second control valve 12 on the water supply pipeline 1, and includes a pressure reducing mechanism 21 for automatically adjusting the opening according to the flow rate of the pump packing leakage water. When the water supply pressure to the shaft seal water chamber 31 is relatively large, it can adjust the water supply pressure to the shaft seal water chamber 31 to make the water supply pressure to the shaft seal water chamber 31 meet the requirements of the shaft seal.

[0028] The pressure stabilizing pipeline 2 includes a bypass pipeline 22 arranged in parallel with the second control valve 12 on the water supply pipeline 1. The pressure reducing mechanism 21 includes a third control valve 211 arranged on the bypass pipeline 22.

[0029] Preferably, the third control valve 211 is a pressure reducing valve. In order to enable the pressure reducing valve to be in a normal opening, the pressure reducing mechanism 21 further includes a pressure dividing pipeline 212 connected to the pressure stabilizing pipeline 2 and a fourth control valve 213 arranged on the pressure dividing pipeline 212. The pressure dividing pipeline 212 is connected to the downstream of the third control valve 211 on the bypass pipeline 22.

[0030] When the flow rate through the third control valve 211 is greater than the pressure required by the shaft seal water chamber 31, the fourth control valve 213 can be opened to allow a part of the water passing through the third control valve 211 to be discharged through the pressure dividing pipeline 212, so that the third control valve 211 can be in a normal opening and the pressure of the shaft seal water chamber 31 will not be too high.

[0031] The fourth control valve 213 is a regulating valve, which can adjust the opening degree of the fourth control valve 213 according to the flow rate of the pressure stabilizing pipeline 2 to meet the water supply pressure flowing to the shaft seal water chamber 31. In this embodiment, the regulating valve is a globe stop valve.

[0032] Further, a fifth control valve 221 and a sixth control valve 222 are respectively provided on the bypass pipeline 22, upstream and downstream of the third control valve 211.

[0033] Preferably, in this embodiment, the first control valve 11 and the second control valve 12 are isolation valves, and the fifth control valve 221 and the sixth control valve 222 are also isolation valves respectively, which can control the on-off of the corresponding positions.

[0034] Further, the first control valve 11, the second control valve 12, the fifth control valve 221, and the sixth control valve 222 are all globe stop isolation valves.

[0035] Preferably, a pressure detection mechanism 13 is provided on the water supply pipeline 1 between the first control valve 11 and the pressure stabilizing pipeline 2, which can detect the water supply pressure flowing to the shaft seal water chamber 31 in real time. The pressure detection mechanism 13 can be a pressure gauge or a pressure meter, etc.

[0036] When the pump shaft seal water system is officially put into operation normally, the first control valve 11, the fifth control valve 221, and the sixth control valve 222 are opened, the second control valve 12 is closed, and the third control valve 211 automatically adjusts the valve opening degree according to the pump packing leakage water flow rate to maintain the pump shaft seal injection pressure stable at 3.5 - 3.8 bar.g; when the third control valve 211 has faults such as pressure regulating setting value drift, the second control valve 12 is opened to conduct emergency water injection for the pump shaft seal water, and the fifth control valve 221 and the sixth control valve 222 are closed to isolate and disassemble and repair the pressure reducing valve.

[0037] A bypass pipeline 22 and an emptying pressure dividing pipeline 212 are added to the pump shaft seal water pipeline for supplying SEC (auxiliary system) from SEP (drinking water system), and a pressure reducing valve is added to the pressure stabilizing pipeline 2 to reduce the shaft seal water pressure of the SEC pump. At the same time, it ensures the normal supply of shaft seal water in case of pressure reducing valve failure.

[0038] A globe stop regulating valve is provided on the pressure dividing pipeline 212, and the main functions of this pipeline are as follows:

[0039] Regulate the shaft seal water flow rate flowing through the third control valve 211 to avoid jamming caused by the third control valve 211 always being in a small opening state due to too small flow rate;

[0040] Utilize the local high point of the pipeline to discharge the air in the shaft seal water pipeline and improve the shaft seal water pressure fluctuation caused by air accumulation.

[0041] The shaft seal water pressure reducing device for Pump 3 solves the problems related to abnormal shaft seal water leakage of SEC pumps in nuclear power plants and abnormal wear of shaft sleeves and pump covers. Implementing the shaft seal water pressure reducing device for Pump 3 can achieve the matching of the water supply pressure for the pump packing seal and the design pressure of the stuffing box, while meeting the leakage rate of the packing cooling. The packing seal has a maintenance-free function for 3 years, eliminating the need for frequent adjustment of the packing and saving the maintenance costs of replacing the pump cover and shaft sleeve.

[0042] The shaft seal water pressure reducing device for Pump 3 reduces the pressure of the shaft seal water for the important service water pump 3, eliminates the phenomenon of abnormally large shaft seal leakage, and avoids unplanned isolation and disassembly and repair of the SEC pump due to abnormal wear of the pump cover and shaft sleeve. It has the function of maintenance-free pump shaft seal, avoiding a large amount of manpower and material resources input for the operation and maintenance of pump equipment, and improving the operation safety and economy of nuclear power plants.

[0043] Understandably, the above technical features can be combined arbitrarily without limitation.

[0044] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A pressure reducing device for the shaft seal water of a water pump, characterized in that, it includes: A water supply pipeline (1), connected between a drinking water system and the shaft seal water chamber (31) of a water pump (3), for supplying water to the shaft seal water chamber (31). A first control valve (11) and a second control valve (12) are provided on the water supply pipeline (1); A pressure stabilizing pipeline (2), arranged in parallel with the second control valve (12) on the water supply pipeline (1), including a pressure reducing mechanism (21) for automatically adjusting the opening according to the leakage water flow of the pump packing; The pressure stabilizing pipeline (2) includes a bypass pipeline (22) arranged in parallel with the second control valve (12) on the water supply pipeline (1); The pressure reducing mechanism (21) includes a third control valve (211) arranged in the bypass pipeline (22); The third control valve (211) is a pressure reducing valve. The pressure reducing mechanism (21) further includes a pressure dividing pipeline (212) connected to the pressure stabilizing pipeline (2), and a fourth control valve (213) arranged on the pressure dividing pipeline (212). The pressure dividing pipeline (212) is connected to the downstream of the third control valve (211) on the bypass pipeline (22).

2. The pressure reducing device for the shaft seal water of a water pump according to claim 1, characterized in that, The fourth control valve (213) is a regulating valve.

3. The pressure reducing device for the shaft seal water of a water pump according to claim 2, characterized in that, The regulating valve is a cut-off type regulating valve.

4. The pressure reducing device for the shaft seal water of a water pump according to claim 1, characterized in that, The first control valve (11) and the second control valve (12) are isolation valves.

5. The pressure reducing device for the shaft seal water of a water pump according to claim 1, characterized in that, A fifth control valve (221) and a sixth control valve (222) are further provided on the bypass pipeline (22) respectively upstream and downstream of the third control valve (211).

6. The pressure reducing device for the shaft seal water of a water pump according to claim 5, characterized in that, The fifth control valve (221) and the sixth control valve (222) are isolation valves respectively.

7. The pressure reducing device for the shaft seal water of a water pump according to claim 1, characterized in that, The first control valve (11), the second control valve (12), the fifth control valve (221), and the sixth control valve (222) are all cut-off type isolation valves.

8. The pressure reducing device for the shaft seal water of a water pump according to claim 1, characterized in that, A pressure detection mechanism (13) is provided on the water supply pipeline (1) between the first control valve (11) and the pressure stabilizing pipeline (2).

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