阅读说明：本技术 用于非能动核电厂核主泵的外置式轴向力平衡装置 (External axial force balancing device for nuclear main pump of passive nuclear power plant ) 是由 马柏松 吴放 缪正强 黄晓杰 庄亚平 贾子瑜 于 2019-11-01 设计创作，主要内容包括：本发明公开了一种用于非能动核电厂核主泵的外置式轴向力平衡装置,包括加压装置,加压装置与存储冷却水的容器相连通,加压装置的压力出口通过管路与疏水阀连接,疏水阀与所述核主泵的疏水管嘴连接,疏水阀与加压装置间的管路上设有压力传感器；压力传感器和所述核主泵内的转速传感器与控制系统相连,控制系统控制加压装置输出压力的大小。本发明无需改变核主泵的内部结构,通过外置式的轴向力平衡装置提供辅助提升力,部分抵消转子组件的重力,可使得下推力轴承及下推力盘之间的水膜在核主泵启动过程中尽快建立、在核主泵停止过程中继续保持；同时也改善了核主泵启动/停止期间下推力盘的受力状况,使得下推力盘的使用寿命得以延长。(The invention discloses external axial force balancing devices for a nuclear main pump of a passive nuclear power plant, which comprise 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, a pipeline between the drain valve and the pressurizing device is provided with a pressure sensor, the pressure sensor and a 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.)

1. The external axial force balancing device 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.

Wherein, the auxiliary jacking force F can be calculated by the formula F ═ P1-P2 multiplied by S,

p1 — pressure of the chamber between the rotor and stator assemblies;

p2 — pressure of reactor coolant, i.e. pressure of fluid in the pump housing;

s-the cross-sectional area of the shaft at the heat shield/labyrinth seal.

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 the constant pressure of is output outwards through 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 of the upper portion of the pressure accumulating box through a pipeline, cooling water is stored in the pressure accumulating box, a control end of the automatic pressure regulating valve is connected with the control system, outlet pressure of the automatic pressure regulating valve is controlled by the control system, the cooling water in the pressure accumulating box outputs cooling water with constant pressure from an outlet of the lower portion of the pressure accumulating box under the action of the nitrogen pressure, an outlet of the upper portion of the pressure accumulating box is respectively connected with a pressure relief valve and a safety valve for limiting the pressure through pipelines, an outlet of.

Technical Field

The invention discloses an external axial force balancing device for a nuclear main pump of a passive nuclear power plant, and belongs to the technical field of nuclear main pumps of nuclear power plants. The passive nuclear power plant is a nuclear power plant adopting technologies such as AP1000, CAP1000 and CAP 1400.

Background

As shown in figure 1, nuclear main pumps 1-1 are respectively hung on two nozzles of a lower end socket of each steam generator 1-2 of the passive nuclear power plant, a hydraulic part of each pump is arranged on the upper part, and a motor part is arranged on the lower part, wherein after flowing out of the lower end socket of the steam generator 1-2, the reactor coolant is sucked into the nuclear main pumps 1-1 along the axial direction, flows into a main pipeline 1-3 through outlet nozzles of the nuclear main pumps 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 cycles are 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.

The heat shield/labyrinth seal 3 allows reactor coolant to flow at a low flow rate into the chamber between the stator assembly 19 and the rotor assembly 5 and also allows cooling water to flow at a low flow rate into the pump housing 1 to maintain a pressure substantially at across the heat shield/labyrinth seal 3.

The cooling water in the cavity between the stator assembly 19 and the rotor assembly 5 is cooled by the external heat exchanger 20, the cooled cooling water enters the cavity 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 part of the rotor assembly 5, shown by a dotted line, part of the rotor assembly) on the rotor assembly 5, the cooling water discharged by the auxiliary impeller is divided into two paths, a small part of the cooling water flows downwards, cools 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 and then returns to the inlet of the auxiliary impeller, and a large part of the cooling water flows upwards, cools the stator assembly 19, the rotor assembly 5 and the upper flywheel 4.

The nuclear main pump axial force is a resultant force formed by the axial force (namely, the lifting force caused by the rotation of the impeller 2) which is formed by the pressure difference of liquid acting on the front cover plate and the rear cover plate of the impeller 2 and the self weight of the rotor assembly 5, in 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, when the rotating speed of the nuclear main pump exceeds fixed value, the nuclear main pump axial force turns, 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, the lower thrust bearing 10 provides upward thrust for the rotor assembly 5 through the lower thrust disc 9, when the rotating 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, 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.

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, the lower thrust bearing 10 provides upward thrust for the rotor assembly 5 through the lower thrust disc 9. in the aspect of , the gland-seal-free pump thrust bearing uses a water-lubricated bearing, when the rotating speed is low, the 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 the long-term reliable operation of the water-lubricated bearing can be influenced due to the long-time dry friction state. in the aspect of , during the start/stop of the nuclear main pump, the lower thrust disc 9 is easily subjected to a large force, and finally the nuclear main pump can be stopped.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: 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 problems, the technical scheme of the invention is to provide an external axial force balancing device for a nuclear main pump of a passive nuclear power plant, which is characterized by comprising a pressurizing device, wherein the pressurizing device is communicated with a container for storing cooling water through a pipeline; 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.

Wherein, the auxiliary jacking force F can be calculated by the formula F ═ P1-P2 multiplied by S,

p1 — pressure of the chamber between the rotor and stator assemblies;

p2 — pressure of reactor coolant, i.e. pressure of fluid in the pump housing;

s-the cross-sectional area of the shaft at the heat shield/labyrinth seal.

Preferably, a flow sensor and a temperature sensor are further arranged on a pipeline between the pressurizing device and the steam trap.

Preferably, implementation schemes of the pressurizing device include 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, cooling water with constant pressure of 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 an isolating valve through a pipeline, the outlet of the isolating valve is connected with an inlet of a check valve through a pipeline, and the outlet of the check valve is a pressure outlet of the pressurizing device.

Preferably, another implementation schemes of the pressurization device include an automatic pressure regulating valve, an inlet of the automatic pressure regulating valve is communicated with a pipeline of a nuclear power plant high-pressure nitrogen system 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 tank through a pipeline, cooling water is stored in the pressure accumulating tank, a control end of the automatic pressure regulating valve is connected with a control system, high-pressure nitrogen with constant pressure is output to the pressure accumulating tank under the control of the control system, the cooling water in the pressure accumulating tank outputs cooling water with constant pressure from an outlet at the lower part of the pressure accumulating tank, an outlet at the upper part of the pressure accumulating tank is respectively connected with a safety valve and a safety valve playing a role in pressure limiting through pipelines, an outlet of the pressure relief valve and an outlet.

The invention has the advantages that 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, 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 before the nuclear main pump is completely stopped from a certain rotating speed, 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 the lower thrust disc can be established as soon as possible when the nuclear main pump is started and is continuously maintained in the stopping process of the nuclear main pump, the water-lubricated bearing can reliably run for a long time by steps, meanwhile, the stress condition of the lower thrust disc during the starting or stopping of the nuclear main pump is improved, the service life of the.

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 view of example 1 of the present invention;

FIG. 4 is a control block diagram of embodiment 1 of the present invention;

FIG. 5 is a schematic structural view of example 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 invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.