CN211116827U - External axial force balancing device for passive nuclear power plant nuclear main pump - Google Patents
External axial force balancing device for passive nuclear power plant nuclear main pump Download PDFInfo
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- CN211116827U CN211116827U CN201921878319.9U CN201921878319U CN211116827U CN 211116827 U CN211116827 U CN 211116827U CN 201921878319 U CN201921878319 U CN 201921878319U CN 211116827 U CN211116827 U CN 211116827U
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Abstract
The utility model discloses an external axial force balancing device for a nuclear main pump of a passive nuclear power plant, which comprises a pressurizing device, wherein the pressurizing device is communicated with a container for storing cooling water, a pressure outlet of the pressurizing device is connected with a drain valve through a pipeline, the drain valve is connected with a drain nozzle of the nuclear main pump, and a pipeline between the drain valve and the pressurizing device is provided with a pressure sensor; the pressure sensor and the rotating speed sensor in the nuclear main pump are connected with a control system, and the control system controls the output pressure of the pressurizing device. The utility model provides auxiliary lifting force through the external axial force balancing device without changing the internal structure of the nuclear main pump, partially offsets the gravity of the rotor assembly, and can enable the water film between the lower thrust bearing and the lower thrust disc to be established as soon as possible in the starting process of the nuclear main pump and to be continuously maintained in the stopping process of the nuclear main pump; meanwhile, the stress condition of the lower thrust disc during the starting/stopping period of the nuclear main pump is improved, so that the service life of the lower thrust disc is prolonged.
Description
Technical Field
The utility model relates to an external axial force balancing unit for passive nuclear power plant's nuclear main pump belongs to nuclear power plant nuclear main pump technical field. The passive nuclear power plant is a nuclear power plant adopting technologies such as AP1000, CAP1000 and CAP 1400.
Background
The nuclear main pump is mainly used for conveying reactor coolant to a reactor and realizing circulation of the reactor coolant between the reactor and a steam generator. As shown in the attached figure 1, a nuclear main pump 1-1 is respectively hung on two nozzles of a lower seal head of each steam generator 1-2 of the passive nuclear power plant, the hydraulic part of the pump is arranged at the upper part, and the electric motor part is arranged at the lower part. After flowing out of a lower end socket of the steam generator 1-2, the reactor coolant is sucked into the nuclear main pump 1-1 along the axial direction, flows into the main pipeline 1-3 through an outlet nozzle of the nuclear main pump 1-1 in the radial direction, then flows through the reactor 1-4, and returns to the steam generator 1-2 through the main pipeline 1-3, so that a cycle is completed.
Compared with other nuclear power plants, the passive nuclear power plant adopts a shaft seal-free pump as a nuclear main pump. As shown in fig. 2, the whole rotor assembly of the nuclear main pump is contained in the pressure boundary of the reactor coolant, and the pump unit has no dynamic sealing structure of a transmission shaft between the pump shell and the motor, so that the possibility that the reactor coolant in the pump shell leaks to the outside through the dynamic sealing structure is fundamentally eliminated.
When the nuclear main pump operates, the heat shield/labyrinth seal 3 separates the reactor coolant in the pump shell and the cooling water in the cavity between the stator assembly 19 and the rotor assembly 5, and plays a role in heat insulation. The heat shield/labyrinth seal 3 allows reactor coolant to flow at a small flow rate into the cavity between the stator assembly 19 and the rotor assembly 5 and also allows cooling water in the cavity between the stator assembly 19 and the rotor assembly 5 to flow at a small flow rate into the pump housing 1 to maintain a substantially uniform pressure across the heat shield/labyrinth seal 3.
The cooling water in the chamber between the stator assembly 19 and the rotor assembly 5 is cooled by the external heat exchanger 20, and the cooled cooling water enters the chamber between the stator assembly 19 and the rotor assembly 5 through the lower part of the nuclear main pump and is sucked by an auxiliary impeller (see the lower dotted line of the rotor assembly 5, which is a part of the rotor assembly) on the rotor assembly 5. Cooling water discharged by the auxiliary impeller is divided into two paths, a small part of cooling water flows downwards, and returns to an inlet of the auxiliary impeller after cooling the upper thrust bearing 6, the upper thrust disc 7, the lower flywheel 8, the lower thrust disc 9 and the lower thrust bearing 10; most of the cooling water flows upward, cools the stator assembly 19, the rotor assembly 5, and the upper flywheel 4, and then returns to the external heat exchanger 20.
The axial force of the nuclear main pump is a resultant force formed by an axial force (i.e., a lifting force caused by the rotation of the impeller 2) directed to a suction port of the impeller 2 and a self-weight of the rotor assembly 5, which is formed by a pressure difference between the front cover plate and the rear cover plate of the impeller 2 when liquid acts on the impeller 2. During the starting/stopping and running processes of the nuclear main pump, the gravity of the rotor assembly 5 is constant, but the lifting force caused by the rotation of the impeller 2 is increased along with the increase of the rotating speed, and when the rotating speed of the nuclear main pump exceeds a certain value, the axial force of the nuclear main pump is turned. When the rotating speed is lower than the value, the lifting force generated by the rotation of the impeller 2 is smaller than the gravity of the rotor assembly 5, and the lower thrust bearing 10 provides upward thrust for the rotor assembly 5 through the lower thrust disc 9; when the rotation speed is higher than the value, the lifting force generated by the rotation of the impeller 2 is larger than the gravity of the rotor assembly 5, and the upper thrust bearing 6 provides downward thrust for the rotor assembly 5 through the upper thrust disc 7. The upper thrust disc 7 and the lower thrust disc 9 are respectively positioned at the upper side and the lower side of the lower flywheel 8, and the upper side and the lower side of the upper flywheel 4 are not provided with the thrust discs.
During the start/stop of the nuclear main pump, the rotating speed of the rotor assembly is low, the lifting force generated by the rotation of the impeller 2 is smaller than the gravity of the rotor assembly 5, and the lower thrust bearing 10 provides upward thrust for the rotor assembly 5 through the lower thrust disc 9. On one hand, the thrust bearing of the shaft seal-free pump uses a water-lubricated bearing, when the rotating speed is low, a water film between the lower thrust bearing 10 and the lower thrust disc 9 is not completely built or damaged, the friction pair is in a dry friction state to a certain extent, and long-term reliable operation of the water-lubricated bearing can be influenced if the friction pair is in the dry friction state for a long time. On the other hand, during the start/stop of the nuclear main pump, the lower thrust plate 9 is easy to malfunction due to the large stress on the lower thrust plate 9, and finally the nuclear main pump may malfunction and stop.
Disclosure of Invention
The to-be-solved technical problem of the utility model is: the problems that a lower thrust bearing and a lower thrust disc are easy to wear and damage due to unbalanced axial force in the starting and stopping processes of the nuclear main pump are solved through the external device, and the internal structure of the nuclear main pump is not required to be modified.
In order to solve the technical problem, the technical scheme of the utility model is to provide an external axial force balancing unit for passive nuclear power plant's nuclear main pump, its characterized in that, including pressure device, pressure device is linked together through pipeline and the container of storage cooling water, and pressure outlet of pressure device is connected with the trap through the pipeline, and the trap is connected with the drain nozzle of nuclear main pump, is equipped with pressure sensor on the pipeline between trap and pressure device; the pressure sensor and the rotating speed sensor in the nuclear main pump are connected with a control system, and the control system controls the output pressure of the pressurizing device.
Preferably, a flow sensor and a temperature sensor are further arranged on a pipeline between the pressurizing device and the steam trap.
Preferably, an implementation scheme of the pressurizing device includes a water storage tank, cooling water is stored in the water storage tank, a vent hole is formed in the top of the water storage tank and communicated with the atmosphere, the bottom of the water storage tank is connected with an inlet of a displacement pump through a pipeline, a control end of the displacement pump is connected with a control system, the cooling water with a certain pressure is output outwards from an outlet under the control of the control system, an outlet of the displacement pump is connected with an inlet of an isolation valve through a pipeline, an outlet of the isolation valve is connected with an inlet of a check valve through a pipeline, and an outlet of the check valve is a pressure outlet of the pressurizing device.
Preferably, another implementation scheme of the pressurizing device comprises an automatic pressure regulating valve, an inlet of the automatic pressure regulating valve is communicated with a pipeline of a high-pressure nitrogen system of the nuclear power plant through a pipeline, an outlet of the automatic pressure regulating valve is connected with an inlet of a check valve through a pipeline, an outlet of the check valve is connected with an inlet at the upper part of a pressure accumulating box through a pipeline, and cooling water is stored in the pressure accumulating box; the outlet of the upper part of the pressure storage tank is respectively connected with a pressure relief valve and a safety valve which plays a role in limiting pressure through pipelines, the outlet of the pressure relief valve and the outlet of the safety valve are both communicated with the atmosphere, and the control end of the automatic pressure regulating valve and the control end of the pressure relief valve are both connected with a control system.
The utility model discloses the beneficial effect who gains is: when the nuclear main pump is started or stopped, a pressurizing device is used for injecting high-pressure water into a cavity between a rotor assembly and a stator assembly of the nuclear main pump through a drain valve at the lower part of the nuclear main pump, when the nuclear main pump is started and accelerated to a certain rotating speed or stopped from the certain rotating speed to the complete stop, the pressure of the cavity between the rotor assembly and the stator assembly is maintained to be higher than the pressure in a pump shell, the pressure difference acts on a shaft of the nuclear main pump (the stress area is the cross section of the shaft at the heat shield/labyrinth seal position), auxiliary jacking force is provided for the rotor assembly of the nuclear main pump, the gravity of the rotor assembly is partially offset, a water film between a lower thrust bearing and a lower thrust disc can be built as soon as possible when the nuclear main pump is started and is continuously maintained in the stopping process of the; meanwhile, the stress condition of the lower thrust disc during the starting or stopping of the nuclear main pump is improved, so that the service life of the lower thrust disc is prolonged. The balance control of the axial force of the nuclear main pump is completely realized through an external device, and the internal structure of the nuclear main pump is not required to be modified.
Drawings
FIG. 1 is a schematic view of the installation location of a nuclear main pump;
FIG. 2 is a schematic structural diagram of a nuclear main pump of a conventional passive nuclear power plant;
fig. 3 is a schematic structural diagram of embodiment 1 of the present invention;
fig. 4 is a control block diagram of embodiment 1 of the present invention;
fig. 5 is a schematic view of embodiment 2 of the present invention;
fig. 6 is a control block diagram of embodiment 2 of the present invention.
Detailed Description
In order to make the present invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.
Example 1
An external axial force balancing device for a nuclear main pump of a passive nuclear power plant is shown in fig. 3 and comprises a pressure sensor 21, a flow sensor 22, a temperature sensor 23, a check valve 24, an isolation valve 25, a displacement pump 26, a water tank 15 and a pipeline. The water tank 15 stores cooling water, and the water tank 15 is communicated with the atmospheric environment and is kept in a normal pressure state. The pressure in the chamber between the rotor assembly and the stator assembly is automatically adjusted by adjusting the positive displacement pump 26.
The control block diagram is shown in fig. 4, and as the rotating speed of the nuclear main pump increases or decreases, the lifting force generated by the rotation of the impeller 2 increases or decreases synchronously, and the auxiliary jacking force on the rotor assembly is changed by synchronously adjusting the pressure of the cavity between the rotor assembly and the stator assembly so as to partially offset the gravity of the rotor assembly.
The rotational speed signal measured by the rotational speed sensor 14 and the pressure signal measured by the pressure sensor 21 are transmitted as inputs to a control system 27, which control system 27 regulates the pressure by controlling the displacement pump 26.
The flow sensor and the temperature sensor are arranged for monitoring the flow and the temperature of cooling water entering the nuclear main pump so as to be referred by production personnel and judge the influence of the cooling water on the internal cooling condition of the nuclear main pump.
Before the nuclear main pump performs starting or stopping operation, the drain valve 13 of the nuclear main pump is opened manually, and the control system 27 automatically adjusts the volume pump 26 to adjust the pressure of the cavity between the rotor assembly and the stator assembly to a proper value. The control system 27 adjusts the pressure in the chamber between the rotor assembly and the stator assembly based on the speed signal from the speed sensor 14 and the pressure signal from the pressure sensor 21.
In the starting process of the nuclear main pump, when the rotating speed is higher than a certain value, the lifting force generated by the rotation of the impeller is enough, the device does not need to work continuously any more, the pressure of a cavity between the rotor assembly and the stator assembly is gradually reduced continuously by adjusting the positive displacement pump 26, after the pressure is consistent with the pressure of the reactor coolant (namely the pressure of fluid in a pump shell), the drain valve 13 is manually closed, and the device stops working.
When the nuclear main pump operates normally, the lifting force generated by the rotation of the impeller 2 is larger than the gravity of the rotor assembly 5, the device does not need to work, and the drain valve 13 keeps a closed state.
Example 2
An external axial force balancing device for a nuclear main pump of a passive nuclear power plant is shown in figure 5 and comprises a pressure sensor 21, a flow sensor 22, a temperature sensor 23, a check valve 24, an automatic pressure regulating valve 28, a pressure accumulating tank 29, a pressure relief valve 30, a safety valve 31 and a pipeline. The pressure storage tank 29 is stored with cooling water and is connected with a high-pressure nitrogen system of a nuclear power plant through a pipeline, and the automatic pressure regulating valve 28 and the pressure relief valve 30 automatically regulate the pressure of nitrogen in the pressure storage tank 24 under the control of the control system 27, so that the pressure of a cavity between the rotor assembly and the stator assembly is controlled.
The rotation speed signal measured by the rotation speed sensor 14 and the pressure signal measured by the pressure sensor 21 are used as input and transmitted to the control system 27, and the control system 27 controls the automatic pressure regulating valve 28 and the pressure relief valve 30 to automatically regulate the outlet pressure, so that the pressure of the cavity between the rotor assembly and the stator assembly is regulated.
When the automatic pressure regulating valve 28 is fully closed, the control system 27 controls the opening of the pressure relief valve 30 to further regulate the pressure if it is still necessary to further reduce the pressure in the chamber between the rotor assembly and the stator assembly.
Before the nuclear main pump performs starting or stopping operation, the drain valve 13 of the nuclear main pump is manually opened, the outlet pressure of the automatic pressure regulating valve 28 is regulated, and the pressure of a cavity between the rotor assembly and the stator assembly is regulated to be proper. The control system 27 adjusts the pressure in the chamber between the rotor assembly and the stator assembly based on the speed signal from the speed sensor 14 and the pressure signal from the pressure sensor 21.
In the starting process of the nuclear main pump, when the rotating speed is higher than a certain value, the lifting force generated by the rotation of the impeller is enough, the device is not required to work any more, the pressure of the pressure storage tank 24 is continuously and gradually reduced, when the pressure is consistent with the pressure of the reactor coolant (namely the pressure of fluid in a pump shell), the drain valve 13 is closed, and the device is stopped from working.
When the nuclear main pump operates normally, the lifting force generated by the rotation of the impeller 2 is larger than the gravity of the rotor assembly 5, the device does not need to work, and the drain valve 13 keeps a closed state.
Claims (4)
1. An external axial force balancing device for a nuclear main pump of a passive nuclear power plant is characterized by comprising a pressurizing device, wherein the pressurizing device is communicated with a container for storing cooling water, a pressure outlet of the pressurizing device is connected with a drain valve through a pipeline, the drain valve is connected with a drain nozzle of the nuclear main pump, and a pipeline between the drain valve and the pressurizing device is provided with a pressure sensor; the pressure sensor and the rotating speed sensor in the nuclear main pump are connected with a control system, and the control system controls the output pressure of the pressurizing device.
2. The external axial force balancing device for the nuclear main pump of the passive nuclear power plant as claimed in claim 1, wherein a flow sensor and a temperature sensor are further provided on a pipeline between the pressurizing device and the drain valve.
3. The external axial force balancing device for the nuclear main pump of the passive nuclear power plant as claimed in claim 1 or 2, wherein the pressurizing device comprises a water storage tank, cooling water is stored in the water storage tank, a vent hole is formed in the top of the water storage tank and communicated with the atmosphere, the bottom of the water storage tank is connected with an inlet of the displacement pump through a pipeline, a control end of the displacement pump is connected with a control system, the cooling water with certain pressure is output outwards from an outlet under the control of the control system, the outlet of the displacement pump is connected with an inlet of the isolating valve through a pipeline, and an outlet of the isolating valve is connected with an inlet of the check valve through a pipeline.
4. The external axial force balancing device for the nuclear main pump of the passive nuclear power plant as claimed in claim 1 or 2, wherein the pressurizing device comprises an automatic pressure regulating valve, an inlet of the automatic pressure regulating valve is communicated with a pipeline of a high-pressure nitrogen system of the nuclear power plant through a pipeline, an outlet of the automatic pressure regulating valve is connected with an inlet of a check valve through a pipeline, an outlet of the check valve is connected with an inlet at the upper part of the pressure accumulating tank through a pipeline, and cooling water is stored in the pressure accumulating tank; the outlet of the upper part of the pressure storage tank is respectively connected with a pressure relief valve and a safety valve which plays a role in limiting pressure through pipelines, the outlet of the pressure relief valve and the outlet of the safety valve are both communicated with the atmosphere, and the control end of the automatic pressure regulating valve and the control end of the pressure relief valve are connected with a control system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921878319.9U CN211116827U (en) | 2019-11-01 | 2019-11-01 | External axial force balancing device for passive nuclear power plant nuclear main pump |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921878319.9U CN211116827U (en) | 2019-11-01 | 2019-11-01 | External axial force balancing device for passive nuclear power plant nuclear main pump |
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| CN211116827U true CN211116827U (en) | 2020-07-28 |
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| CN201921878319.9U Active CN211116827U (en) | 2019-11-01 | 2019-11-01 | External axial force balancing device for passive nuclear power plant nuclear main pump |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110735817A (en) * | 2019-11-01 | 2020-01-31 | 山东核电有限公司 | External axial force balancing device for nuclear main pump of passive nuclear power plant |
| CN114038598A (en) * | 2021-11-04 | 2022-02-11 | 山东核电有限公司 | Control device system and method for passive nuclear power plant |
| CN114038598B (en) * | 2021-11-04 | 2024-04-26 | 山东核电有限公司 | Control device system and method for passive nuclear power plant |
-
2019
- 2019-11-01 CN CN201921878319.9U patent/CN211116827U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110735817A (en) * | 2019-11-01 | 2020-01-31 | 山东核电有限公司 | External axial force balancing device for nuclear main pump of passive nuclear power plant |
| CN114038598A (en) * | 2021-11-04 | 2022-02-11 | 山东核电有限公司 | Control device system and method for passive nuclear power plant |
| CN114038598B (en) * | 2021-11-04 | 2024-04-26 | 山东核电有限公司 | Control device system and method for passive nuclear power plant |
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