Mechanical sealing device for condensed water booster pump

Abstract

The invention belongs to the field of mechanical sealing, and particularly relates to a mechanical sealing device for a condensed water booster pump, which comprises a rotating part and a static part, the rotating part rotates together with a pump shaft, and the static part is connected with a pump cavity; the rotating component comprises a shaft sleeve and a moving ring, and an O-shaped ring B and an O-shaped ring C are arranged between the outer circle of the moving ring and the shaft sleeve; an O-shaped ring A is arranged between the shaft sleeve and the pump shaft; the static component comprises a static ring, a static ring seat, a spring seat and a gland, the gland is fixedly connected to the pump cavity, an O-shaped ring G is arranged between the gland and the pump cavity, and a friction pair is formed between the adjacent end faces of the static ring and the moving ring and serves as a sealing face. An O-shaped ring D is arranged between the back face, away from the sealing face, of the static ring and the static ring seat, an O-shaped ring E is arranged between the static ring seat and the spring seat, and an O-shaped ring F is arranged between the spring seat and the gland. The problems of poor sealing floatability, end face dry friction and the like are solved, the reliability of the sealing performance is improved, and the sealing operation life is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of mechanical seals, and in particular relates to a mechanical seal device for a condensate booster pump. Background Art

[0002] The condensate system is an important system in the secondary circuit of a nuclear power plant. Its main function is to transport condensate from the condenser hot well to the deaerator. In order to ensure the reliable operation of the entire system, the condensate must be desalted, purified, heated, and controlled and regulated as necessary during transportation. At the same time, it provides cooling water, sealing water, cooling water, and control water for related equipment during operation, and also replenishes the steam and water loss during the thermal cycle. Due to the pressure resistance of the desalination device, the condensate of domestic units is boosted in two stages, so a condensate booster pump is installed after the desalination device. The condensate booster pump is particularly important in the condensate system, ensuring the pressure of the entire system. The mechanical seal is one of the key components of the condensate booster pump. The performance and life of the mechanical seal directly determine whether the equipment can operate smoothly.

[0003] The medium of the condensate booster pump is water at a temperature of 49.℃ and a pressure of 3.5MPa, and the speed is 1500r / min. Under such working conditions, the original mechanical seal end face is seriously heated, the non-compensation ring end face has severely worn grooves, and even serious powder loss occurs. No liquid film is formed on the end face, and the mechanical seal is dry rubbed, which aggravates the wear of the seal. In addition, the roughness and hardness of the contact between the spring seat and the compensation ring seat at the O-ring are not enough, which seriously affects the floatability of the mechanical seal, causing mechanical seal leakage and affecting its life. Summary of the invention

[0004] The object of the present invention is to provide a mechanical seal device for a condensate booster pump, which takes into account the influence of the mechanical seal on the deformation of the sealing end face under high-pressure working conditions, the lubrication and cooling measures of the sealing end face of the mechanical seal, and the influence of the secondary seal (O-ring E) on the tracking performance of the sealing end face, thereby solving the difficulties such as poor floating performance of the original seal and dry friction of the end face, improving the sealing operating conditions, and effectively improving 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 condensate booster pump, the device comprising: a rotating component and a stationary component, the rotating component rotates together with the pump shaft, and the stationary component is connected to the pump cavity; the rotating component comprises: a sleeve and a moving ring, the moving ring is installed in the sleeve, and an O-ring B and an O-ring C are arranged between the outer circle of the moving ring and the sleeve; the sleeve is installed on the pump shaft, an O-ring A is arranged between the sleeve and the pump shaft, and the sleeve is fixedly connected to the pump shaft; the stationary component comprises: a stationary ring, a stationary ring seat, a spring seat, and a gland, the gland is fixedly connected to the pump cavity, an O-ring G is arranged between the gland and the pump cavity, the stationary ring is arranged between the moving ring and the stationary ring seat, and a friction pair is formed between the adjacent end faces of the stationary ring and the moving ring as a sealing surface; an O-ring D is arranged between the back side of the stationary ring away from the sealing surface and the stationary ring seat, an O-ring E is arranged between the stationary ring seat and the spring seat, an O-ring F is arranged between the spring seat and the gland, and the spring seat and the gland are connected.

[0007] The shaft sleeve is fixedly connected to the pump shaft via a positioning ring and a key.

[0008] The gland is fixedly connected to the pump chamber via studs and nuts.

[0009] The spring seat and the pressure cover are connected via connecting screws.

[0010] The stationary component also includes a spring, which is compressed between the stationary ring seat and the spring seat.

[0011] The stationary component also includes a throttle ring, which is placed in the gland.

[0012] The material hardness of the static ring is smaller than the material hardness of the dynamic ring.

[0013] The moving ring is made of integral silicon carbide material.

[0014] The stationary ring seat is made of precipitation hardened stainless steel with chromium carbide sprayed on the surface; the spring seat is made of precipitation hardened stainless steel with chromium carbide sprayed on the surface, and the contact part of the floating O-ring E is hardened with a hardness of more than HRC50 and a surface roughness of up to 0.2.

[0015] The beneficial technical effects of the present invention are:

[0016] 1. The present invention provides a mechanical seal device for a condensate booster pump, which can effectively improve the operating performance and service life of the mechanical seal for a condensate booster pump in a condensate system of a pressurized water reactor nuclear power plant.

[0017] 2. In a mechanical sealing device for a condensate booster pump provided by the present invention, the dynamic ring cancels the inlaid structure and adopts an integral silicon carbide material, which has high strength and excellent thermal conductivity, and can better take away the heat from the end face and improve the operation of the end face. In addition, the silicon carbide material has a lower density, which reduces the torque of the rotating parts and also reduces the impact on the anti-rotation pin.

[0018] 3. In a mechanical seal device for a condensate booster pump provided by the present invention, the stationary ring seat and the spring seat are made of precipitation-hardened stainless steel, and the surface is treated with spray chromium carbide. The contact point of the floating O-ring E is hardened with a hardness of HRC50 or above, and the surface roughness is increased by up to 0.2, which can effectively ensure the floatability of the seal, increase the service life of the seal, and improve the tracking performance, effectively overcoming the structure of the original mechanical seal intermediate ring, in which the intermediate ring is connected to the stationary ring with screws, has poor tracking performance, increases leakage points, and has a complex structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of a mechanical sealing device for a condensate booster pump provided by the present invention.

[0020] In the figure: 1- pump shaft; 2- shaft sleeve; 3- O-ring A; 4- O-ring B; 5- O-ring C; 6- moving ring; 7- stationary ring; 8- O-ring D; 9- stationary ring seat; 10- spring; 11- O-ring E; 12- spring seat; 13- throttle ring; 14- connecting screw; 15- positioning ring; 16- O-ring F; 17- pressure cover; 18- nut; 19- stud; 20- O-ring G; 21- pump chamber; 22- key. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0022] The present invention provides a mechanical sealing device for a condensate booster pump, comprising: a rotating component rotating together with a pump shaft 1 , and a stationary component connected to a pump cavity 21 .

[0023] The rotating parts include: a sleeve 2, a moving ring 6, a positioning ring 15, and a key 22. The moving ring 6 is installed in the sleeve 2, and an O-ring B4 and an O-ring C5 are arranged between the outer circle of the moving ring 6 and the sleeve 2; the sleeve 2 is installed on the pump shaft 1, and an O-ring A3 is arranged between the sleeve 2 and the pump shaft 1. The sleeve 2 is fixedly connected to the pump shaft 1 through the positioning ring 15 and the key 22.

[0024] The stationary parts include: a stationary ring 7, a stationary ring seat 9, a spring 10, a spring seat 12, a throttle ring 13, a connecting screw 14, and a gland 17. The gland 17 is fixedly connected to the pump chamber 21 by means of a stud 19 and a nut 18. An O-ring G20 is arranged between the gland 17 and the pump chamber 21. The stationary ring 7 is arranged between the moving ring 6 and the stationary ring seat 9. A friction pair is formed between the adjacent end faces of the stationary ring 7 and the moving ring 6 as a sealing surface. An O-ring D8 is arranged between the back side of the stationary ring 7 away from the sealing surface and the stationary ring seat 9. The spring 10 is compressed between the stationary ring seat 9 and the spring seat 12. An O-ring E11 is arranged between the stationary ring seat 9 and the spring seat 12. An O-ring F16 is arranged between the spring seat 12 and the gland 17. The spring seat 12 and the gland 17 are connected by means of a connecting screw 14. The throttle ring 13 is placed in the gland 17.

[0025] The dynamic ring 6 is made of silicon carbide as a whole, which is a hard ring. It is installed in the shaft sleeve and has no axial compensation capability. The static ring 7 is made of graphite ring, which is a soft ring. It has a compensation element on the back and has axial compensation capability. The material hardness of the static ring 7 is less than that of the dynamic ring 6.

[0026] The stationary ring is installed on the housing of the machine and equipment and is stationary. It fits tightly with the dynamic ring assembly to form the end face friction pair of the mechanical seal to prevent leakage of the sealing medium.

[0027] 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.

[0028] O-ring D8, O-ring E11 and O-ring F16 constitute a static ring sealing ring, which is used to prevent leakage between the static ring and the sealing cover.

[0029] O-ring B4 and O-ring C5 constitute a dynamic ring seal 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 floatability to ensure the normal operation of the mechanical seal friction pair.

[0030] The elastic element (ie, spring 10) mainly plays the role of buffering and compensation.

[0031] The stationary ring seat 9 is made of precipitation hardened stainless steel, and chromium carbide is sprayed on the surface; the spring seat 12 is made of precipitation hardened stainless steel, and chromium carbide is sprayed on the surface.

[0032] The contact part of floating O-ring E11 is hardened to a hardness of HRC50 or above and a surface roughness of up to 0.2.

[0033] 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.

[0034] Example 1

[0035] 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.

[0036] Test conditions:

[0037] Medium: deionized water;

[0038] Test temperature: room temperature;

[0039] Test pressure: 6MPa;

[0040] Acceptance criteria:

[0041] Visual inspection of the gland parts should show no leakage or sweating.

[0042] Mechanical seal leakage ≤5ml / h.

[0043] Example 2

[0044] Operation test: Operation test is carried out after passing the static pressure test.

[0045] Test conditions:

[0046] Medium: deionized water;

[0047] Test temperature: room temperature;

[0048] Test pressure: 4MPa;

[0049] Speed: 1500r / min;

[0050] Test time: The test time is 5h.

[0051] Acceptance criteria: Mechanical seal leakage ≤5ml / h.

[0052] Example 3

[0053] The wear identification test is carried out with clean water as the medium and runs for 100 hours.

[0054] Test conditions:

[0055] Test medium: deionized water;

[0056] Test temperature: room temperature;

[0057] Test pressure: 4Mpa;

[0058] Speed: 1500r / min;

[0059] Test time: The test time is 100h.

[0060] Benchmark Check

[0061] Measure and record the height of the stationary ring assembly before the wear test;

[0062] Mark four directions, measure the altitude and make a record, and take the average altitude of the four directions.

[0063] Test steps

[0064] Step 1. Correctly install the seal to the test bench and connect the pipeline;

[0065] Step 2: Increase the sealing chamber pressure to 4 MPa, increase the test bench speed to 1500 r / min, and run stably for 100 hours under this state.

[0066] Disassembly inspection: measure and record the height of the stationary ring assembly with orientation marks after the wear test;

[0067] Acceptance criteria: The wear of the stationary ring assembly is not greater than 0.01mm.

[0068] All tests passed and met the acceptance criteria.

[0069] 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 condensate booster pump, characterized in that: The device comprises: a rotating component and a stationary component, wherein the rotating component rotates together with the pump shaft (1), and the stationary component is connected to the pump cavity (21); the rotating component comprises: a sleeve (2), a moving ring (6), the moving ring (6) is installed in the sleeve (2), and an O-ring B (4) and an O-ring C (5) are arranged between the outer circle of the moving ring (6) and the sleeve (2); the sleeve (2) is installed on the pump shaft (1), an O-ring A (3) is arranged between the sleeve (2) and the pump shaft (1), and the sleeve (2) is fixedly connected to the pump shaft (1); the stationary component comprises: a stationary ring (7), a stationary ring seat (9), a spring seat (12), a pressure cover (17 ), a gland (17) is fixedly connected to a pump chamber (21), an O-ring G (20) is arranged between the gland (17) and the pump chamber (21), a stationary ring (7) is arranged between a moving ring (6) and a stationary ring seat (9), and a friction pair is formed between the adjacent end faces of the stationary ring (7) and the moving ring (6) as a sealing surface; an O-ring D (8) is arranged between the back side of the stationary ring (7) away from the sealing surface and the stationary ring seat (9), an O-ring E (11) is arranged between the stationary ring seat (9) and the spring seat (12), an O-ring F (16) is arranged between the spring seat (12) and the gland (17), and the spring seat (12) and the gland (17) are connected.

2. A mechanical seal device for a condensate booster pump according to claim 1, characterized in that: The shaft sleeve (2) is fixedly connected to the pump shaft (1) via a positioning ring (15) and a key (22).

3. The mechanical seal device for a condensate booster pump according to claim 1, characterized in that: The gland (17) is fixedly connected to the pump chamber (21) via a stud (19) and a nut (18).

4. The mechanical seal device for a condensate booster pump according to claim 1, characterized in that: The spring seat (12) and the pressure cover (17) are connected via a connecting screw (14).

5. The mechanical seal device for a condensate booster pump according to claim 1, characterized in that: The stationary component also includes a spring (10), which is compressed between the stationary ring seat (9) and the spring seat (12).

6. The mechanical seal device for a condensate booster pump according to claim 1, characterized in that: The stationary component also includes a throttle ring (13), which is placed in the pressure cover (17).

7. The mechanical seal device for a condensate booster pump according to claim 1, characterized in that: The material hardness of the static ring (7) is smaller than the material hardness of the dynamic ring (6).

8. The mechanical seal device for a condensate booster pump according to claim 1, characterized in that: The moving ring (6) is made of integral silicon carbide material.

9. The mechanical seal device for a condensate booster pump according to claim 1, characterized in that: The stationary ring seat (9) is made of precipitation hardened stainless steel with chromium carbide sprayed on the surface; the spring seat (12) is made of precipitation hardened stainless steel with chromium carbide sprayed on the surface, and the contact part of the floating O-ring E (11) is hardened to have a hardness of more than HRC50 and a surface roughness of up to 0.2.

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