Fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device

Abstract

The invention relates to a fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device which is characterized in that a displacement sensor is connected to the tail of a guide rod, the guide rod is fixed between a static ring seat and a shaft sleeve, a static ring is fixedly pressed on the static ring seat, the guide rod and the static ring are rigidly connected together, and the static ring and a moving ring are attached. When the fluid dynamic pressure type mechanical seal is in a non-operation state, the static ring and the movable ring are in an attached state, the distance between the end faces is zero, when the fluid dynamic pressure type mechanical seal starts to work, a layer of micron-sized liquid film can be formed between the static ring and the movable ring, so that the end faces of the static ring and the movable ring are opened, and when the guide rod and the static ring are in rigid connection and the liquid film is generated, the end faces of the static ring and the movable ring are closed. The static ring can move in the axial direction, when the static ring moves, the guide rod is driven to move in the axial direction, and in the state, the thickness of the liquid film can be indirectly detected by measuring the amplitude of vertical displacement of the guide rod. According to the invention, the displacement condition of the end face liquid film change can be effectively collected, and meanwhile, the influence on the mechanical seal operation of the fluid dynamic pressure type nuclear main pump is avoided.

Description

Technical Field

[0001] The invention relates to a fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device, which can effectively collect the displacement of end surface liquid film changes while avoiding the influence on the operation of the fluid dynamic pressure type nuclear main pump mechanical seal. Background Art

[0002] Due to its particularity and importance, the main pump shaft seal has the characteristics of high technical difficulty, high cost, frequent preventive maintenance, and a large inventory of old mechanical seal spare parts. At present, the mainstream (60%) mechanical seals used in the main pumps of domestic pressurized water reactor power plants are static pressure type. Due to the relative friction during operation of static pressure mechanical seals, there is currently no practical experience in directly reusing sealing rings in China. Most power plants adopt a conservative strategy of directly abandoning old sealing rings. A few power plants try to reuse them after grinding, but the success rate is low. Since dynamic pressure seals are relatively late in entering engineering applications compared to static pressure seals, the application practice of dynamic pressure seals in China is still in its infancy, and there is no experience in the reuse of dynamic pressure seals to refer to.

[0003] As the technology matures, fluid dynamic pressure mechanical seal technology is increasingly favored by subsequent main pump manufacturers for its advantages of "no contact wear during operation and long service life", and has gradually become the standard configuration of the main pump of the third-generation nuclear power unit. Promoting the reuse research and practice of dynamic pressure mechanical seals and establishing a set of dynamic pressure mechanical seal reuse system standards for industry reference will fill the gap in the reuse of dynamic pressure mechanical seals in China.

[0004] The key to whether the dynamic pressure seal can operate normally and stably for a long time is whether the end surface liquid film is stable. In order to monitor the operating status of the dynamic pressure seal, it is necessary to install a sensor to monitor the thickness of the liquid film. The displacement sensor can convert the measured physical quantity into an electrical signal to achieve the effect of real-time measurement and recording of mechanical displacement. Therefore, it is effective and feasible to use a displacement sensor to measure the change of liquid film thickness. Summary of the invention

[0005] The purpose of the present invention is to provide a fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device, which on the one hand enables the fluid dynamic pressure type main pump mechanical seal to be tested under normal working conditions, and on the other hand facilitates the collection of displacement change data of the end surface liquid film.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device, a displacement sensor is connected to the tail of a guide rod, the guide rod is fixed between a stationary ring seat and a shaft sleeve, the stationary ring is fixed and pressed on the stationary ring seat, the guide rod and the stationary ring are rigidly connected together, and the stationary ring and the dynamic ring are fitted together.

[0008] When the fluid dynamic pressure type mechanical seal is not in operation, the stationary ring and the dynamic ring are in a fitted state, and the distance between the end faces is 0. When the fluid dynamic pressure type mechanical seal starts to work, a micron-level liquid film will be formed between the stationary ring and the dynamic ring, causing the end faces of the stationary ring and the dynamic ring to open, and the guide rod and the stationary ring are rigidly connected. When the liquid film is generated, the stationary ring can move axially. When the stationary ring moves, it drives the guide rod to undergo axial displacement. In this state, the liquid film thickness can be indirectly detected by measuring the amplitude of the up and down displacement of the guide rod.

[0009] The displacement sensor measures the relative distance between the displacement sensor and the guide rod of the fluid dynamic pressure type nuclear main pump mechanical seal during operation. The change in this measured value can be used to analyze the up and down floating value of the static ring seat, and thus the change in the liquid film thickness between the end faces can be calculated.

[0010] The floating of the stationary ring seat and the stationary ring can be regarded as relative movement, and the displacement floating measurement of the guide rod fixed on the stationary ring seat by the displacement sensor can be regarded as the change of the end surface liquid film thickness.

[0011] The displacement sensor is connected to the tail end of the guide rod through a sensor mounting seat.

[0012] The beneficial effects achieved by the present invention are:

[0013] The measurement problem of the liquid film change between the end faces is solved by monitoring the displacement change of the guide rod; the floating displacement change of the end face liquid film is monitored without affecting the normal operation of the main pump dynamic pressure mechanical seal to reduce the measurement error of the multiplexing limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural diagram of a fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device;

[0015] In the figure: 1. displacement sensor; 2. sensor mounting seat; 3. guide rod; 4. sleeve; 5. moving ring; 6. stationary ring; 7. stationary ring seat. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] The guide rod 3 is installed and fixed on the static ring seat 7. The displacement sensor 1 is connected to the tail of the guide rod 3 to measure the relative distance between the displacement sensor and the guide rod during the operation of the fluid dynamic pressure type nuclear main pump mechanical seal. The change of this measured value can be used to analyze the up and down floating value of the static ring seat 7, and the change of the liquid film thickness between the end faces can be calculated based on this.

[0018] The guide rod 3 is fixed between the stationary ring seat 7 and the shaft sleeve 4. Since the stationary ring 6 is fixed and pressed on the stationary ring seat 7, the floating of the stationary ring seat 7 and the stationary ring 6 can be regarded as relative movement. Therefore, the displacement floating measurement of the guide rod 3 fixed on the stationary ring seat 7 by the displacement sensor 1 can be regarded as the change of the end surface liquid film thickness.

[0019] Since the contact point between the dynamic and static rings is too narrow, it is impossible to measure the thickness of the liquid film by directly placing the sensor at the liquid film, so the thickness of the liquid film is measured by indirect measurement. The displacement sensor 1 is installed on the sensor mounting seat 2, and the guide rod 3 below is tightly fitted to rigidly connect the guide rod 3 and the static ring 6, so that the static ring 6 and the guide rod 3 can be regarded as one. When the fluid dynamic pressure type mechanical seal is not in operation, the static ring 6 and the dynamic ring 5 are in a fitted state, and the distance between the end faces is 0. When the fluid dynamic pressure type mechanical seal starts to work, a layer of micron-level liquid film will be formed between the static ring 6 and the dynamic ring 5, causing the end faces of the static ring 6 and the dynamic ring 5 to open, and the guide rod 3 and the static ring 6 are rigidly connected. When the liquid film is generated, the static ring can move axially. When the static ring moves, it drives the guide rod 3 to undergo axial displacement. In this state, the thickness of the liquid film can be indirectly detected by simply measuring the amplitude of the up and down displacement of the guide rod.

Claims

1. A fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device, characterized in that: The displacement sensor is connected to the tail of the guide rod, the guide rod is fixed between the stationary ring seat and the shaft sleeve, the stationary ring is fixed and pressed on the stationary ring seat, the guide rod and the stationary ring are rigidly connected together, and the stationary ring and the dynamic ring are fitted.

2. The fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device according to claim 1 is characterized in that: When the fluid dynamic pressure type mechanical seal is not in operation, the stationary ring and the dynamic ring are in a fitted state, and the distance between the end faces is 0. When the fluid dynamic pressure type mechanical seal starts to work, a micron-level liquid film will be formed between the stationary ring and the dynamic ring, causing the end faces of the stationary ring and the dynamic ring to open, and the guide rod and the stationary ring are rigidly connected. When the liquid film is generated, the stationary ring can move axially. When the stationary ring moves, it drives the guide rod to undergo axial displacement. In this state, the liquid film thickness can be indirectly detected by measuring the amplitude of the up and down displacement of the guide rod.

3. The fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device according to claim 1 is characterized in that: The displacement sensor measures the relative distance between the displacement sensor and the guide rod of the fluid dynamic pressure type nuclear main pump mechanical seal during operation. The change in this measured value can be used to analyze the up and down floating value of the static ring seat, and thus the change in the liquid film thickness between the end faces can be calculated.

4. The fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device according to claim 1 is characterized in that: The floating of the stationary ring seat and the stationary ring can be regarded as relative movement, and the displacement floating measurement of the guide rod fixed on the stationary ring seat by the displacement sensor can be regarded as the change of the end surface liquid film thickness.

5. The fluid dynamic pressure type nuclear main pump mechanical seal liquid film thickness measuring device according to claim 1 is characterized in that: The displacement sensor is connected to the tail end of the guide rod through a sensor mounting seat.

Images