Method for detecting sealing surface of mechanical seal of nuclear primary pump

Abstract

The present disclosure belongs to the technical field of nuclear power and specifically relates to a sealing surface detection method for a mechanical seal of a nuclear main pump. The sealing surface detection method for the mechanical seal of the nuclear main pump measures the liquid film thickness and temperature of the third-stage mechanical sealing surface of the nuclear main pump under the working state of a test bench for the mechanical seal of the nuclear main pump. The displacement sensor and the temperature sensor installed on the static ring insert measure the displacement change between the static ring insert and the static ring seat (wherein the static ring seat is connected with the static ring as a whole) and the temperature change on the upper surface of the static ring seat when the mechanical seal is working, thereby indirectly reflecting the liquid film thickness value and the temperature value between the sealing end surfaces. The test bench and the sealing surface detection method thereof are widely applicable to the reliability improvement research and verification of the hydrodynamic mechanical seal of the nuclear main pump, and provide a direct verification means for the design, manufacturing, inspection and installation of the mechanical seal of the nuclear main pump.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power technology, specifically relating to a method for detecting the sealing surface of a nuclear main pump mechanical seal. Background Technology

[0002] As a core component of the nuclear main pump, the mechanical seal of the hydrodynamic nuclear main pump directly affects whether the nuclear main pump can operate stably and efficiently for a long time.

[0003] The mechanical seal of a nuclear main pump works by relying on a pair of end faces (stationary ring and rotating ring) that slide relative to each other perpendicular to the pump shaft. Under fluid pressure and the elastic force of the compensation mechanism, they remain in contact, and with the assistance of an auxiliary seal, they achieve a sealing effect. In a static state, the rotating and stationary rings are tightly fitted. During operation, under the pressure of the medium, a tiny gap forms between the sealing end faces. When pressurized medium passes through this gap, a very thin liquid film forms, creating resistance and preventing leakage. Simultaneously, it lubricates the sealing end faces, extending their service life. The thickness of the liquid film between the sealing end faces directly affects the performance of the mechanical seal: if the liquid film is too thick, excessive leakage of the sealed pressurized medium will occur; if the liquid film is too thin, friction between the sealing end faces will increase, the temperature will rise, and the seal's service life will be shortened. The thickness and temperature of the liquid film on the mechanical seal surface during the operation of the nuclear main pump are affected by many factors such as the characteristics of the medium, working conditions (such as sealing surface pressure and temperature), material properties, and application environment. These factors cannot be accurately calculated or predicted theoretically. Therefore, a liquid film detection method is needed to accurately measure the thickness and temperature of the liquid film between the mechanical seal end faces during the operation of the main pump. This will help to better evaluate the working status of the mechanical seal, analyze its working principle, and adjust its installation dimensions to ensure that it is in the optimal working condition. Summary of the Invention

[0004] To overcome the problems existing in related technologies, a method for detecting the sealing surface of a nuclear main pump mechanical seal is provided.

[0005] According to one aspect of the present disclosure, a method for detecting the sealing surface of a nuclear main pump mechanical seal test bench is provided, the method comprising:

[0006] Step 11: Open the upper cover of the mechanical seal of the nuclear main pump and remove the stationary ring insert;

[0007] Step 12: Install a displacement sensor at a first position above the upper end face of the stationary ring seat, near the outer edge of the stationary ring insert, with the lower end of the displacement sensor spaced from the upper end face of the stationary ring seat by a preset gap value.

[0008] Step 13: Install a displacement sensor and a temperature sensor at a second position above the upper end face of the stationary ring seat, near the outer edge of the stationary ring insert. The temperature sensor's measuring head contacts the upper end face of the stationary ring seat, and the first position is different from the second position.

[0009] Step 14: Connect the data cables of the displacement sensor and temperature sensor to the external host computer of the test bench;

[0010] Step 15: Reinstall the stationary ring insert and the upper end cover. After the test bench is started and running smoothly, read and record the liquid film thickness and liquid film temperature on the sealing surface through the host computer.

[0011] In one possible implementation, the method further includes:

[0012] Step 21: Machining mounting holes axially at the positions of the upper end cover and the stationary ring insert directly opposite the edge of the stationary ring seat;

[0013] Step 22: Machining a measuring rod with a length of l;

[0014] Step 23: After the mechanical seal test bench of the nuclear main pump is installed in the normal assembly sequence, insert the measuring rod into the mounting hole, measure the distance b between the lower opening end of the mounting hole and the upper surface of the upper end cover, and the distance a from the upper surface of the upper end cover to the top of the measuring rod, and determine the distance d=lab between the bottom end of the stationary ring insert and the stationary ring seat.

[0015] Step 24: Based on the measurement distance of the displacement sensor, determine the gap value c = de between the lower end of the displacement sensor and the upper end face of the stationary ring seat. c is consistent with the measurement distance, and e is an adjustment parameter.

[0016] Step 25: Complete the installation of the displacement sensor according to the gap value c.

[0017] In one possible implementation, the method further includes:

[0018] Step 31: Based on the measured d, complete the installation of the temperature sensor, so that the temperature sensor's measuring head contacts the upper end face of the stationary ring.

[0019] In one possible implementation, the displacement value t is obtained by processing the measured value s collected by the displacement sensor according to the following formula: t = s / 10000 × 0.5. The displacement value is used to characterize the thickness of the liquid film on the sealing surface.

[0020] In one possible implementation, the temperature sensor includes a temperature instrument for displaying temperature data collected by the temperature sensor in real time, and the displacement sensor includes a displacement instrument for displaying data collected by the displacement sensor in real time.

[0021] The beneficial effects of this disclosure are as follows: The method for detecting the sealing surface of the mechanical seal of the nuclear main pump disclosed herein measures the liquid film thickness and temperature of the third-stage mechanical seal surface of the nuclear main pump under the working condition of the nuclear main pump mechanical seal test bench. By using displacement and temperature sensors installed on the stationary ring insert, the displacement change between the stationary ring insert and the stationary ring seat (wherein the stationary ring seat and stationary ring are connected as one unit) and the temperature change on the upper surface of the stationary ring seat are measured during the operation of the mechanical seal, thereby indirectly reflecting the liquid film thickness and temperature values ​​between the sealing end faces. The test bench and sealing surface detection method of this disclosure are widely applicable to the research and verification of reliability improvement of hydrodynamic mechanical seals of nuclear main pumps, providing a direct verification means for the design, manufacture, inspection, and installation of nuclear main pump mechanical seals. Attached Figure Description

[0022] Figure 1 This is an axial sectional view of a nuclear main pump mechanical seal test bench according to an exemplary embodiment.

[0023] Figure 2 yes Figure 1 A schematic diagram of inserting a measuring rod in area A.

[0024] Figure 3 yes Figure 1 A schematic diagram of inserting a displacement sensor in region A.

[0025] Figure 4 yes Figure 1 A schematic diagram of inserting a temperature sensor in region A.

[0026] In the picture:

[0027] 1. Upper bearing housing cover; 2. Upper bearing; 3. Upper bearing housing; 4. Upper end cover; 5. Pump shaft;

[0028] 6. Mechanical seal; 7. Sealing body; 8. Lower end cover; 9. Lower bearing housing; 10. Lower bearing end cover;

[0029] 11. Lower bearing; 12. Lower bushing; 13. Lower bearing housing cover; 14. Belt; 15. Pump end pulley;

[0030] 16. Upper shaft sleeve; 17. Upper bearing end cover; 18. Stationary ring; 19. Rotary ring; 20. Pump end bracket;

[0031] 21. Pump end pulley bearing; 22. Coupling; 23. Stationary ring insert; 24. Stationary ring seat;

[0032] 25. Eddy current sensor; 26. Temperature sensor; 27. Measuring rod. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] The method for testing the sealing surface of the mechanical seal of the nuclear main pump disclosed herein is applied to the test bench of the mechanical seal of the nuclear main pump. Figure 1 This is an axial sectional view of a nuclear main pump mechanical seal test bench according to an exemplary embodiment, such as... Figure 1 As shown, the nuclear main pump mechanical seal test bench includes: upper bearing housing cover 1, upper bearing 2, upper bearing housing 3, upper end cover 4, pump shaft 5, mechanical seal 6, sealing body 7, lower end cover 8, lower bearing housing 9, lower bearing end cover 10, lower bearing 11, lower shaft sleeve 12, lower bearing housing cover 13, belt 14, pump end pulley 15, upper shaft sleeve 16, upper bearing end cover 17, stationary ring 18, dynamic ring 19, pump end bracket 20, pump end pulley bearing 21, and coupling 22. The above components are assembled together according to the installation method of nuclear main pump mechanical seal in relevant technologies.

[0035] See Figure 1 Multiple pairs of stationary rings 18 and rotating rings 19 are arranged around the outside of the pump shaft 5 perpendicular to its axis via a compensation mechanism. The working principle of the nuclear main pump mechanical seal is that the relatively sliding end faces of each pair of stationary rings 18 and rotating rings 19 remain in contact under the action of fluid pressure and the elasticity of the compensation mechanism, and are combined with auxiliary sealing to achieve a sealing effect. Under static conditions, the rotating ring 19 and stationary ring 18 are tightly fitted. When the nuclear main pump is working, a tiny gap is formed between the sealing end faces of the rotating ring 19 and stationary ring 18 under the action of medium pressure. When pressurized medium passes through this gap, a very thin liquid film is formed, creating resistance and preventing the medium from leaking outward. At the same time, the sealing end faces are lubricated, extending their service life.

[0036] See Figures 1 to 4 The methods disclosed herein may include:

[0037] Step 11: Open the upper cover of the mechanical seal of the nuclear main pump and remove the stationary ring insert;

[0038] Step 12: Install a displacement sensor at a first position above the upper end face of the stationary ring seat, near the outer edge of the stationary ring insert, with the lower end of the displacement sensor spaced from the upper end face of the stationary ring seat by a preset gap value.

[0039] Step 13: Install a displacement sensor and a temperature sensor at a second position above the upper end face of the stationary ring seat, near the outer edge of the stationary ring insert. The temperature sensor's measuring head contacts the upper end face of the stationary ring seat, and the first position is different from the second position.

[0040] Step 14: Connect the data cables of the displacement sensor and temperature sensor to the external host computer of the test bench (not shown in the figure).

[0041] Step 15: Reinstall the stationary ring insert and the upper end cover. After the test bench is started and running smoothly, read and record the liquid film thickness and liquid film temperature on the sealing surface through the host computer.

[0042] It should be noted that appropriate displacement sensors (such as eddy current sensors) and temperature sensors (such as thermocouple sensors) can be selected according to the measurement requirements. This disclosure does not limit the types of displacement sensors and temperature sensors.

[0043] Since a certain gap needs to be maintained between the displacement sensor and the measured object (e.g., the gap between the eddy current displacement sensor and the measured object is 0.05~0.55mm), in order to accurately measure the installation position of the displacement sensor, mounting holes are machined axially at the positions of the upper end cover and the stationary ring insert opposite the edge of the stationary ring seat, and a measuring rod is also machined. See [link to documentation]. Figure 2 The measuring rod has a length of l. After the mechanical seal of the nuclear main pump is installed in the normal assembly sequence on the test bench, the measuring rod is inserted into the mounting hole. The distance b between the lower opening end of the mounting hole and the upper surface of the upper end cover, and the distance a from the upper surface of the upper end cover to the top of the measuring rod are measured. Using the known values ​​of l, a, and b, the distance d between the bottom end of the stationary ring insert and the stationary ring seat is calculated, i.e., d = lab. In this way, according to the detection characteristics and measurement distance of the displacement sensor, the gap value c between the lower end of the displacement sensor and the upper end face of the stationary ring seat can be controlled within the required range, c = de (where c is the gap value, e is the adjustment parameter, and the eddy current displacement sensor is set to a gap value of c = d - 0.3 mm). Then, as follows... Figure 3 As shown, the displacement sensor is installed according to the determined gap value.

[0044] The temperature sensor's probe needs to contact the measured object to accurately measure the temperature. After calculating the distance 'd' between the stationary ring insert and the stationary ring seat, the specific installation position of the temperature sensor is determined. Based on 'd', the installation depth of the temperature sensor's probe is confirmed to ensure contact between the probe and the upper surface of the stationary ring. Then, as follows... Figure 4 As shown, the temperature sensor is then fixed onto the stationary ring insert.

[0045] After the eddy current sensor or temperature sensor is installed, the measurement signal line is led out from the side hole of the upper end cover and connected to the display and storage device of the host computer. Start the nuclear main pump mechanical seal test bench, and after it runs smoothly, perform testing and record the data.

[0046] In one application example, the displacement value measured by the displacement sensor under a certain pressure is converted to: displacement value = measured data / 10000mv × 0.5mm.

[0047] The converted displacement values ​​are shown in Table 1:

[0048] Table 1

[0049]

[0050] In another application example, the temperature measurement value can be read directly from the instrument, and the measurement value can be recorded as shown in Table 2:

[0051] Table 2

[0052]

[0053] This disclosure discloses a method for detecting the sealing surface of a nuclear main pump mechanical seal. Under the operating conditions of a nuclear main pump mechanical seal test bench, the liquid film thickness and temperature of the third-stage mechanical seal surface are measured. Displacement and temperature sensors installed on the stationary ring insert are used to measure the displacement changes between the stationary ring insert and the stationary ring seat (wherein the stationary ring seat and stationary ring are integrally connected) and the temperature changes on the upper surface of the stationary ring seat during mechanical seal operation. This indirectly reflects the liquid film thickness and temperature values ​​between the sealing end faces. The test bench and sealing surface detection method disclosed herein are widely applicable to the reliability improvement research and verification of hydrodynamic mechanical seals for nuclear main pumps, providing a direct verification method for the design, manufacture, inspection, and installation of nuclear main pump mechanical seals.

[0054] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for testing the sealing surface of a nuclear main pump mechanical seal on a test bench, characterized in that, The method includes: Step 11: Open the upper cover of the mechanical seal of the nuclear main pump and remove the stationary ring insert; Step 12: Install a displacement sensor at a first position above the upper end face of the stationary ring seat, near the outer edge of the stationary ring insert, with the lower end of the displacement sensor spaced from the upper end face of the stationary ring seat by a preset gap value. Step 13: Install a displacement sensor and a temperature sensor at a second position above the upper end face of the stationary ring seat, near the outer edge of the stationary ring insert. The temperature sensor's measuring head contacts the upper end face of the stationary ring seat, and the first position is different from the second position. Step 14: Connect the data cables of the displacement sensor and temperature sensor to the external host computer of the test bench; Step 15: Reinstall the stationary ring insert and the upper end cover. After the test bench is started and running smoothly, read and record the liquid film thickness and liquid film temperature on the sealing surface through the host computer.

2. The method according to claim 1, characterized in that, The method further includes: Step 21: Machining mounting holes axially at the positions of the upper end cover and the stationary ring insert opposite the edge of the stationary ring seat; Step 22: Process a measuring rod with a length of l; Step 23: After the mechanical seal test bench of the nuclear main pump is installed in the normal assembly sequence, insert the measuring rod into the mounting hole, measure the distance b between the lower opening end of the mounting hole and the upper surface of the upper end cover, and the distance a from the upper surface of the upper end cover to the top of the measuring rod, and determine the distance d=lab between the bottom end of the stationary ring insert and the stationary ring seat. Step 24: Based on the measurement distance of the displacement sensor, determine the gap value c = de between the lower end of the displacement sensor and the upper end face of the stationary ring seat. c is consistent with the measurement distance, and e is an adjustment parameter. Step 25: Complete the installation of the displacement sensor according to the gap value c.

3. The method according to claim 2, characterized in that, The method further includes: Step 31: Based on the measured d, complete the installation of the temperature sensor so that the temperature sensor's measuring head contacts the upper end face of the stationary ring.

4. The method according to claim 1, characterized in that, The displacement value t is obtained by processing the measured value s collected by the displacement sensor according to the following formula: t = s / 10000 × 0.

5. The displacement value is used to characterize the thickness of the liquid film on the sealing surface.

5. The method according to claim 1, characterized in that, The temperature sensor includes a temperature instrument for displaying the temperature data collected by the temperature sensor in real time, and the displacement sensor includes a displacement instrument for displaying the data collected by the displacement sensor in real time.

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