Mechanical sealing device for main water supply booster pump

Abstract

The invention belongs to the field of nuclear power station main water supply booster pump operation, and relates to a mechanical sealing device for a main water supply booster pump, which comprises a rotating part and a static part, the rotating component comprises a shaft sleeve and a movable ring, an O-shaped ring D is arranged between the outer circle of the movable ring and the shaft sleeve, and an O-shaped ring A and an adjusting pad are arranged between the shaft sleeve and the pump shaft; the static part comprises a static ring, a static ring seat, a spring seat, a liquid distribution ring and a gland, and an O-shaped ring F is arranged between the gland and the spring seat; a friction pair is formed between adjacent end surfaces of the static ring and the moving ring as a sealing surface; two O-shaped rings C are arranged between the back face, away from the sealing face, of the static ring and the static ring seat, an O-shaped ring B is arranged between the static ring seat and the spring seat, a threaded pin is arranged on the static ring seat, an O-shaped ring E is arranged at the position of the liquid distribution ring and the pump cavity, an O-shaped ring G is arranged at the position of the gland and the pump cavity, and an anti-rotating pin is arranged between the static ring seat and the spring seat. The sealing performance reliability is improved, and the sealing service life is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of operation of a main feed water pre-pump of a nuclear power plant, and in particular relates to a mechanical sealing device for a main feed water pre-pump. Background Art

[0002] Nuclear power is divided into nuclear island and conventional island. The reactor cooler system of nuclear island generates heat, and water is supplied to steam generator through the main feed water system of conventional island to remove heat and generate steam to drive steam turbine to generate electricity. Therefore, the main feed water system of conventional island is the key auxiliary equipment of power station. Since the main feed water pump has a certain cavitation margin, it is generally necessary to increase the pressure of pipeline water through booster pre-pump before the water inlet of feed water pump to ensure that the main feed water pump will not produce cavitation due to too low suction pressure, thereby avoiding damage to the main feed water pump. Therefore, the main feed water pre-pump is particularly important in the main feed water system to ensure the pressure of the whole system. As one of the components of the main feed water pre-pump, the performance and service life of the mechanical seal directly determine whether the equipment can run smoothly.

[0003] The medium pumped by the main water supply front pump is water supply with a temperature of 177.3℃ and a pressure of 1.1MPa, and the speed is 1500r / min. Under such working conditions, the temperature in the original mechanical seal cavity is too high, resulting in the failure of the sealing end face to enter the liquid in time, the failure to lubricate the sealing end face, and the failure to form a liquid film. The mechanical seal is dry friction, resulting in increased wear of the compensation ring, which seriously affects the service life. In addition, the roughness and hardness of the O-ring contact between the spring seat and the compensation ring seat are not enough, which seriously affects the floatability of the mechanical seal, causing mechanical seal leakage and affecting the service life. Summary of the invention

[0004] The object of the present invention is to provide a mechanical seal device for a main water supply pre-pump, which takes into account the influence of the mechanical seal on the deformation of the sealing end face under stable working conditions, the lubrication and cooling measures of the sealing end face of the mechanical seal, and the influence of the secondary seal on the tracking performance of the sealing end face, and thoroughly solves the difficulties such as poor floating performance of the original seal and dry friction of the end face, improves the sealing operating conditions, and improves the reliability of the sealing performance and the sealing operating life.

[0005] The technical solution to achieve the purpose of the present invention is:

[0006] A mechanical seal device for a main water supply pre-pump, the device comprising: a rotating part and a stationary part, the rotating part rotates together with the pump shaft, and the stationary part is connected to the pump chamber; the rotating part comprises: a sleeve, a moving ring, the moving ring is installed in the sleeve, an O-ring D is arranged between the outer circle of the moving ring and the sleeve, the sleeve is installed on the pump shaft, the sleeve is fixedly connected to the pump shaft, and an O-ring A and an adjustment pad are arranged between the sleeve and the pump shaft; the stationary part comprises: a stationary ring, a stationary ring seat, a spring seat, a liquid distribution ring, a gland, and the gland is connected to the pump shaft. The spring seat is fixedly connected, and an O-ring F is arranged between the pressure cover and the spring seat; the static ring is arranged between the dynamic ring and the static ring seat, and a friction pair is formed between the adjacent end faces of the static ring and the dynamic ring as a sealing surface; two O-rings C are arranged between the back side of the static ring away from the sealing surface and the static ring seat, and an O-ring B is arranged between the static ring seat and the spring seat, a threaded pin is arranged on the static ring seat, an O-ring E is arranged between the liquid distribution ring and the pump cavity, an O-ring G is arranged between the pressure cover and the pump cavity, and an anti-rotation pin is arranged between the static ring seat and the spring seat.

[0007] The shaft sleeve is fixedly connected to the pump shaft via a set screw.

[0008] The gland is fixedly connected to the spring seat via connecting screws.

[0009] The stationary component further comprises a spring which is compressed between the stationary ring seat and the spring seat.

[0010] The anti-rotation pin is connected and locked by means of screws.

[0011] The material hardness of the static ring is smaller than the material hardness of the dynamic ring.

[0012] The dynamic ring adopts a structure in which a hard alloy outer circle is inlaid with titanium material, and comprises an outer metal layer and an inner hard alloy layer.

[0013] The stationary ring adopts a floating integral graphite ring structure.

[0014] The spring seat is made of precipitation hardened stainless steel, and the surface is treated with sprayed chromium carbide. The floating O-ring B is hardened to have a hardness of more than HRC50 and a surface roughness of up to 0.2.

[0015] The inner diameter of the liquid distribution ring is used to limit the position, so as to prevent the sleeve from sliding and causing the static ring seat and the static ring to fall off when the set screw is loosened; a guide hole is opened on the liquid distribution ring, and when the dynamic ring and the sleeve rotate, a fluid dynamic pressure effect is generated, and the sealing end face is circulated and cooled through the guide hole, thereby improving the sealing service life.

[0016] The beneficial technical effects of the present invention are:

[0017] 1. In a mechanical seal device for a main water supply pre-pump provided by the present invention, the dynamic ring adopts a structure in which a hard alloy outer circle is inlaid with titanium material, which effectively improves the strength of the dynamic ring. A groove is made on the outer circle titanium material to facilitate assembly and disassembly and to check whether the dynamic ring is installed in place.

[0018] 2. In a mechanical seal device for a main water supply pre-pump provided by the present invention, the stationary ring adopts a floating integral graphite ring structure, which improves the ability of the stationary ring to resist pressure deformation, enhances the anti-interference and tracking capabilities of the stationary ring, and at the same time has good lubrication ability, improves the operating environment of the seal and increases the operating life.

[0019] 3. In a mechanical seal device for a main water supply pre-pump provided by the present invention, the spring seat is made of precipitation hardened stainless steel, and the surface is sprayed with chromium carbide. The floating O-ring B is hardened with a hardness of HRC50 or above and a surface roughness of up to 0.2, which can effectively ensure the floatability of the seal and increase the service life of the seal.

[0020] 4. In the mechanical seal device for the main water supply pre-pump provided by the present invention, the liquid distribution ring uses the inner diameter to limit the position, so as to prevent the sleeve from sliding and causing the static ring seat and the static ring to fall off when the set screw is loosened. It also plays a role of pre-installation. A guide hole is opened on the liquid distribution ring. When the dynamic ring and the sleeve rotate, a fluid dynamic pressure effect is generated, and the sealing end face is circulated and cooled through the guide hole, thereby improving the sealing service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a mechanical sealing device for a main water supply pre-pump provided by the present invention.

[0022] In the figure: 1-spring; 2-spring seat; 3-O-ring A; 4-O-ring B; 5-threaded pin; 6-stationary ring; 7-adjusting pad; 8-O-ring C; 9-moving ring; 10-O-ring D; 11-liquid distribution ring; 12-O-ring E; 13-stationary ring seat; 14-anti-rotation pin; 15-screw; 16-O-ring F; 17-O-ring G; 18-sleeve; 19-pump shaft; 20-pressure cover; 21-fastening screw; 22-connecting screw; 23-pump chamber. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figure 1 As shown, the present invention provides a mechanical sealing device for a main water supply pre-pump, comprising:

[0025] A rotating part that rotates with the pump shaft 19 and a stationary part that is connected to the pump chamber 23;

[0026] The rotating part includes: a sleeve 18, a moving ring 9, and a set screw 21. The moving ring 9 is installed in the sleeve 18. An O-ring D10 is arranged between the outer circle of the moving ring 9 and the sleeve 18. The sleeve 18 is installed on the pump shaft 19. An O-ring A3 and an adjustment pad 7 are arranged between the sleeve 18 and the pump shaft 19. A set screw 21 is provided to fix the sleeve 18 and the pump shaft 19.

[0027] The stationary parts include: a stationary ring 6, a stationary ring seat 13, a spring 1, a spring seat 2, a liquid distribution ring 11, a connecting screw 22, and a gland 20. The gland 20 is fixedly connected to the spring seat 2 by the connecting screw 22. An O-ring F16 is arranged between the gland 20 and the spring seat 2. The stationary ring 6 is arranged between the dynamic ring 9 and the stationary ring seat 13. The adjacent end faces of the stationary ring 6 and the dynamic ring 9 form a friction pair as a sealing surface. Two O-rings are arranged between the back of the stationary ring 6 away from the sealing surface and the stationary ring seat 13. O-ring C8, spring 1 is compressed between stationary ring seat 13 and spring seat 2, an O-ring B4 is provided between stationary ring seat 13 and spring seat 2, a threaded pin 5 is provided on stationary ring seat 13 to withstand the torque brought by the stationary ring, O-ring E12 is provided between liquid distribution ring 11 and pump chamber 23, O-ring G17 is provided between pressure cover 20 and pump chamber 23, an anti-rotation pin 14 is provided between stationary ring seat 13 and spring seat 2, and the anti-rotation pin 14 is connected and locked by screw 15.

[0028] The dynamic ring 9 is made of cemented carbide and is a hard ring. It is installed in the shaft sleeve and does not have axial compensation capability. The static ring 6 is made of graphite and is a soft ring. It has a compensation element on the back and has axial compensation capability. The material hardness of the static ring 6 is less than that of the dynamic ring 9.

[0029] The stationary ring assembly is installed on the housing of the machine equipment and is stationary. It fits tightly with the dynamic ring to form the end face friction pair of the mechanical seal to prevent leakage of the sealing medium.

[0030] The moving ring assembly rotates with the rotating shaft and fits tightly with the stationary ring to prevent leakage of the sealing medium. The moving ring and the stationary ring end face slide relative to each other. Due to the mutual friction between the sealing end faces, wear will inevitably occur. At this time, the moving ring can move axially due to the buffer compensation mechanism, thereby maintaining good contact between the sealing end faces.

[0031] O-ring B4, O-ring C8, O-ring E12 and O-ring F16 constitute a static ring sealing ring, which is used to prevent leakage between the static ring and the sealing cover.

[0032] The O-ring A3, the adjusting washer 7 and the O-ring D10 constitute a dynamic ring sealing ring, which is used to prevent leakage of the annular gap between the dynamic ring and the rotating shaft, and at the same time make the dynamic ring have a certain floating property to ensure the normal operation of the mechanical seal friction pair.

[0033] The elastic element (i.e., spring 1) mainly plays a role of buffering and compensation.

[0034] The dynamic ring 9 adopts a structure of a hard alloy outer circle inlaid with titanium material, including an outer metal layer and an inner hard alloy layer, which improves the strength, and a groove is made on the outer circle titanium material to facilitate assembly and disassembly and check whether the dynamic ring is installed in place.

[0035] The stationary ring 6 adopts a floating integral graphite ring structure, which improves the stationary ring's ability to resist pressure deformation, enhances the stationary ring's anti-interference and tracking capabilities, and at the same time has good lubrication capabilities, improves the sealing operating environment and increases the operating life.

[0036] The spring seat 2 is made of precipitation hardened stainless steel, and the surface is sprayed with chromium carbide. The floating O-ring B4 is hardened with a hardness of more than HRC50 and a surface roughness of up to 0.2, which can effectively ensure the sealing floatability and increase the sealing service life.

[0037] The minimum size of the inner hole of the liquid distribution ring 11 is smaller than the maximum outer circle of the stationary ring seat 13. If the fixing screw 21 falls off, the liquid distribution ring 11 can be stuck to the stationary ring seat 13, that is, the liquid distribution ring 11 uses the inner diameter to limit the position to prevent the fixing screw 21 from loosening and the sleeve 18 from sliding, causing the stationary ring seat 13 and the stationary ring 6 to fall off.

[0038] At the same time, it also plays a role of pre-installation. A guide hole is opened on the liquid distribution ring 11. When the dynamic ring 9 and the sleeve 18 rotate, a fluid dynamic pressure effect is generated, and the sealing end face is circulated and cooled through the guide hole, thereby increasing the sealing service life.

[0039] The following examples are used to verify whether the mechanical seal device for a low-pressure drain pump provided by the present invention meets the on-site requirements.

[0040] Example 1

[0041] Static pressure test, according to the provisions of standard GB / T14211, the static pressure test is carried out at 1.25 times the maximum working pressure of the product, and the pressure is maintained for 15 minutes. The mechanical seal gland belongs to the pressure-bearing boundary, and the water pressure test needs to be carried out at 1.5 times the mechanical seal design pressure (or maximum pressure), so the static pressure test is carried out at 1.5 times the mechanical seal design pressure (or maximum pressure), and the pressure is maintained for 30 minutes.

[0042] Test conditions:

[0043] Medium: deionized water;

[0044] Test temperature: room temperature;

[0045] Test pressure: 2.25MPa;

[0046] Acceptance criteria:

[0047] Visual inspection of the gland parts should show no leakage or sweating.

[0048] Mechanical seal leakage ≤5ml / h.

[0049] Example 2

[0050] Operation test: Operation test is carried out after passing the static pressure test.

[0051] Test conditions:

[0052] Medium: deionized water;

[0053] Test temperature: room temperature;

[0054] Test pressure: 1.5MPa;

[0055] Speed: 1500r / min;

[0056] Test time: The test time is 5h.

[0057] Acceptance criteria: Mechanical seal leakage ≤5ml / h.

[0058] Example 3

[0059] The wear identification test is carried out with clean water as the medium and runs for 200 hours.

[0060] Test conditions:

[0061] Test medium: deionized water;

[0062] Test temperature: room temperature;

[0063] Test pressure: 1.5Mpa;

[0064] Speed: 1500r / min;

[0065] Test time: The test time is 200h.

[0066] Benchmark Check

[0067] Measure and record the height of the stationary ring assembly before the wear test;

[0068] Mark four directions, measure the altitude and make a record, and take the average altitude of the four directions.

[0069] Test steps

[0070] Step 1. Correctly install the seal to the test bench and connect the pipeline;

[0071] Step 2: Increase the sealing chamber pressure to 1.5 MPa, increase the test bench speed to 1500 r / min, and run stably for 200 hours in this state.

[0072] Disassembly inspection: measure and record the height of the stationary ring assembly with orientation marks after the wear test;

[0073] Acceptance criteria: The wear of the stationary ring assembly is not greater than 0.015mm.

[0074] All tests passed and met the acceptance criteria.

[0075] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A mechanical seal device for a main water supply pre-pump, characterized in that: The device comprises: a rotating component and a stationary component, wherein the rotating component rotates together with the pump shaft (19), and the stationary component is connected to the pump chamber (23); the rotating component comprises: a shaft sleeve (18), a moving ring (9), the moving ring (9) is installed in the shaft sleeve (18), an O-ring D (10) is arranged between the outer circle of the moving ring (9) and the shaft sleeve (18), the shaft sleeve (18) is installed on the pump shaft (19), the shaft sleeve (18) is fixedly connected to the pump shaft (19), and an O-ring A (3) and an adjustment pad (7) are arranged between the shaft sleeve (18) and the pump shaft (19); the stationary component comprises: a stationary ring (6), a stationary ring seat (13), a spring seat (2), a liquid distribution ring (11), and a pressure cover (20), the pressure cover (20) is fixedly connected to the spring seat (2), and the pressure cover (20) is fixedly connected to the pump shaft (19). An O-ring F (16) is arranged between the cover (20) and the spring seat (2); the stationary ring (6) is arranged between the moving ring (9) and the stationary ring seat (13); and a friction pair is formed between the adjacent end faces of the stationary ring (6) and the moving ring (9) as a sealing surface; two O-rings C (8) are arranged between the back face of the stationary ring (6) away from the sealing surface and the stationary ring seat (13); an O-ring B (4) is arranged between the stationary ring seat (13) and the spring seat (2); a threaded pin (5) is arranged on the stationary ring seat (13); an O-ring E (12) is arranged between the liquid distribution ring (11) and the pump chamber (23); an O-ring G (17) is arranged between the pressure cover (20) and the pump chamber (23); and an anti-rotation pin (14) is arranged between the stationary ring seat (13) and the spring seat (2).

2. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The shaft sleeve (18) and the pump shaft (19) are fixedly connected via a set screw (21).

3. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The pressure cover (20) is fixedly connected to the spring seat (2) via a connecting screw (22).

4. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The stationary component also includes a spring (1), which is compressed between the stationary ring seat (13) and the spring seat (2).

5. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The anti-rotation pin (14) is connected and locked by a screw (15).

6. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The material hardness of the static ring (6) is smaller than the material hardness of the dynamic ring (9).

7. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The moving ring (9) adopts a structure in which a hard alloy outer circle is inlaid with titanium material, and comprises an outer metal layer and an inner hard alloy layer.

8. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The stationary ring (6) adopts a floating integral graphite ring structure.

9. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The spring seat (2) is made of precipitation hardened stainless steel, and the surface is treated with sprayed chromium carbide. The floating O-ring B (4) is hardened to a hardness of more than HRC50 and a surface roughness of up to 0.

2.

10. A mechanical seal device for a main water supply pre-pump according to claim 1, characterized in that: The liquid distribution ring (11) uses the inner diameter to limit the position, so as to prevent the sleeve (18) from sliding and causing the static ring seat (13) and the static ring (6) to fall off when the set screw (21) is loosened; a guide hole is provided on the liquid distribution ring (11), and when the dynamic ring (9) and the sleeve (18) rotate, a fluid dynamic pressure effect is generated, and the sealing end face is circulated and cooled through the guide hole, thereby improving the sealing service life.

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