Mechanical sealing device for low-pressure heater drainage pump

Abstract

The invention belongs to the field of nuclear power station low-pressure heater drainage pump operation, and particularly relates to a mechanical sealing device for a low-pressure heater drainage 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, a compensation ring assembly, a push ring assembly and a spring seat, and the shaft sleeve is fixedly connected with the pump shaft; the static part comprises a non-compensation ring and a gland; an O-shaped ring C is arranged between the gland and the pump cavity, and a friction pair is formed between the adjacent end faces of the compensation ring assembly and the non-compensation ring to serve as a sealing face; an O-shaped ring B is arranged between the back face, away from the sealing face, of the compensation ring assembly and the push ring assembly, and two O-shaped rings A are arranged between the non-compensation ring and the gland. According to the device, the influence on deformation of the sealing end face under the high-temperature working condition is considered, meanwhile, lubricating and cooling measures of the sealing end face of the mechanical seal are also considered, the sealing operation condition is effectively improved, and safe and reliable operation at the high temperature of 130 DEG C can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of operation of a low-pressure heater drain pump in a nuclear power plant, and in particular relates to a mechanical sealing device for a low-pressure heater drain pump. Background Art

[0002] The low-pressure drain pump sends saturated condensate from the low-pressure heater, air heater or drain tank to the deaerator or other places to speed up the deoxidation process.

[0003] The drain pump delivers high-quality water. If there is no drain pump, the low-pressure drain will be led into the steam generator. The medium temperature is high, which will affect the vacuum degree of the unit, causing the vacuum degree to drop and reducing the operating efficiency of the unit.

[0004] The existing mechanical seals have a general ability to resist deformation and use a common lug transmission method, which is prone to leakage. Summary of the invention

[0005] The purpose of the present invention is to provide a mechanical seal device for a low-pressure steam pump, which not only takes into account the influence of high temperature working conditions on the deformation of the sealing end face, but also takes into account the lubrication and cooling measures of the sealing end face of the mechanical seal. By arranging an O-ring on the back of the compensation ring assembly, the deformation resistance of the sealing surface is effectively improved, thereby reducing the risk of leakage. At the same time, the spring seat and the compensation ring assembly are connected by a transmission screw to achieve a transmission stabilization effect, further reduce the risk of leakage, and effectively improve the operating conditions of the seal, so that it can operate safely and reliably at a high temperature of 130°C.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A mechanical seal device for a low-pressure steam pump, the device comprises: 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 compensation ring assembly, a push ring assembly, and a spring seat, and the sleeve is fixedly connected to the pump shaft; the stationary part comprises: a non-compensating ring and a gland, the gland is fixedly connected to the pump chamber, and an O-ring C is arranged between the gland and the pump chamber; the non-compensating ring, the compensation ring assembly, and the push ring assembly are installed on the outer circle of the sleeve, the compensation ring assembly is arranged between the push ring assembly and the non-compensating ring, the spring seat is located on the side of the push ring assembly away from the compensation ring assembly, and a positioning step is provided on the sleeve to determine the position of the spring seat; a friction pair is formed between the adjacent end faces of the compensation ring assembly and the non-compensating ring as a sealing surface; an O-ring B is arranged between the back side of the compensation ring assembly away from the sealing surface and the push ring assembly, and two O-rings A are arranged between the non-compensating ring and the gland.

[0008] The device also includes a spring compressed between the push ring assembly and the spring seat.

[0009] The spring seat and the push ring assembly are connected via a transmission screw.

[0010] The shaft sleeve is fixedly connected to the pump shaft via a locking nut.

[0011] The gland is fixedly connected to the pump chamber via studs and nuts.

[0012] The compensation ring assembly is an inlaid structure, and is made of cemented carbide-titanium alloy; the compensation ring assembly includes an outer metal layer and an inner metal layer, the outer metal layer is the compensation ring seat material, and is made of titanium alloy, and the inner metal layer is the compensation ring material, and is made of cemented carbide.

[0013] The non-compensation ring is made of integral graphite material.

[0014] The O-ring A, O-ring B and O-ring C are made of fluororubber.

[0015] A throttling ring is arranged in the pump cavity on one side close to the gland, and the throttling ring is installed in cooperation with the gland.

[0016] A step is provided on one side of the throttling ring along the circumferential direction, the step matches with the gland, and the throttling ring and the gland are installed by matching with the step.

[0017] The beneficial technical effects of the present invention are:

[0018] 1. The mechanical sealing device for a low-pressure drain pump provided by the present invention can balance the axial forces exerted on most friction pairs by arranging an O-ring on the back of the compensation ring assembly, so that the deformation resistance of the sealing surface is effectively improved, thereby reducing the risk of leakage.

[0019] 2. The present invention provides a mechanical seal device for a low-pressure drain pump, which ensures the coaxiality of the assembly by arranging two O-rings on the outer circle of the non-compensation ring, thereby reducing the influence of the vibration generated by the pump group during high-speed rotation on the friction pair. At the same time, the two sealing rings can also prevent leakage.

[0020] 3. In the mechanical seal device for a low-pressure drain pump provided by the present invention, the compensation ring component uses a combination of cemented carbide and titanium alloy. The cemented carbide has high strength and certain anti-oxidation and corrosion capabilities under high temperature conditions, which can ensure that the mechanical seal operates well under high temperature conditions.

[0021] 4. The mechanical seal device for a low-pressure drain pump provided by the present invention can make the throttling ring directly cooperate with the gland through the special-shaped design of the throttling ring, avoiding the use of a clamping ring for fixation, saving installation space, and being convenient and reliable.

[0022] 5. In a mechanical seal device for a low-pressure drain pump provided by the present invention, the spring seat and the compensation ring assembly are connected and transmitted by a transmission screw, which is different from the lug transmission of a conventional balanced mechanical seal. The transmission method achieves the advantages of stable transmission and space saving, and effectively reduces the risk of leakage.

[0023] 6. In the mechanical seal device for a low-pressure drain pump provided by the present invention, the fluororubber selected for O-ring A, O-ring B, and O-ring C can ensure that at a high temperature of 130°C, O-ring A, O-ring B, and O-ring C are prevented from aging, cracking, hardening, and losing elasticity, and can still meet the sealing requirements after being subjected to high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic structural diagram of a mechanical sealing device for a low-pressure heater drain pump provided by the present invention;

[0025] Figure 2 This is an enlarged view of two sealing rings of a non-compensation ring in a mechanical sealing device for a low-pressure steam pump provided by the present invention;

[0026] Figure 3 The present invention provides a schematic structural diagram of a throttling ring in a mechanical seal device for a low-pressure drain pump.

[0027] In the figure: 1-locking nut; 2-sleeve; 3-throttling ring; 4-O-ring A; 5-non-compensating ring; 6-compensating ring assembly; 7-push ring assembly; 8-spring; 9-setting screw; 10-pump chamber; 11-pump shaft; 12-spring seat; 13-driving screw; 14-O-ring B; 15-O-ring C; 16-nut; 17-stud; 18-pressure cover. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0029] like Figure 1 As shown, the present invention provides a mechanical sealing device for a low-pressure steam pump, comprising: a rotating component rotating together with a pump shaft 11 , and a stationary component connected to a pump chamber 10 .

[0030] The rotating parts include: a locking nut 1, a shaft sleeve 2, a compensation ring assembly 6, a push ring assembly 7, and a spring seat 12. The locking nut 1 fixes the shaft sleeve 2 and the pump shaft 11.

[0031] The stationary parts include: a non-compensating ring 5, a spring 8, and a gland 18. The gland 18 is fixedly connected to the pump chamber 10 by means of a stud 17 and a nut 16, and an O-ring C15 is arranged between the gland 18 and the pump chamber 10; the non-compensating ring 5, the compensating ring assembly 6, and the push ring assembly 7 are mounted on the outer circle of the sleeve 2, the compensating ring assembly 6 is arranged between the push ring assembly 7 and the non-compensating ring 5, and a friction pair is formed between the adjacent end faces of the compensating ring assembly 6 and the non-compensating ring 5 as a sealing surface; an O-ring B14 is arranged between the back side of the compensating ring assembly 6 away from the sealing surface and the push ring assembly 7; the spring seat 12 is located on the side of the push ring assembly 7 away from the compensating ring assembly 6, a positioning step is arranged on the sleeve 2 to determine the position of the spring seat 12, and the spring 8 is compressed between the push ring assembly 7 and the spring seat 12; two O-rings A4 are arranged between the compensating ring assembly 6 and the gland 18.

[0032] The spring seat 12 and the push ring assembly 7 are connected by a transmission screw 13, which is different from the lug transmission of a conventional balanced mechanical seal. The transmission mode achieves the advantages of stable transmission and space saving.

[0033] The non-compensation ring 5 (i.e., the stationary ring) is installed on the housing of the machine equipment and is stationary. It and the compensation ring assembly 6 fit closely together to form an end face friction pair of the mechanical seal to prevent leakage of the sealing medium.

[0034] The compensation ring assembly 6 (i.e., the dynamic ring assembly) rotates with the rotating shaft and fits tightly with the non-compensation ring 5 to prevent leakage of the sealing medium. The compensation ring assembly 6 slides relative to the end surface of the non-compensation ring 5. Due to the mutual friction between the sealing end surfaces, wear will inevitably occur. At this time, the compensation ring assembly 6 can move axially due to the action of the buffer compensation mechanism, thereby maintaining good contact between the sealing end surfaces.

[0035] The O-ring A4 constitutes a static ring seal ring and is used to prevent leakage between the non-compensating ring 5 and the sealing cover.

[0036] The O-ring B14 constitutes a dynamic ring seal ring, which is used to prevent leakage of the annular gap between the compensation ring assembly 6 and the rotating shaft, and at the same time allows the compensation ring assembly 6 to have a certain floatability to ensure the normal operation of the mechanical seal friction pair.

[0037] The O-ring B14 set on the back of the compensation ring assembly 6 is used to balance the axial force on most of the friction pairs, which can effectively improve the deformation resistance of the sealing surface. In addition, two O-rings A4 are set on the outer circle of the non-compensation ring 5 to ensure its assembly coaxiality and reduce the impact of the vibration generated by the high-speed rotation of the pump group on the friction pair. At the same time, these two O-rings can also prevent leakage. Figure 2 shown.

[0038] The elastic element (i.e., spring 8) mainly plays a role of buffering and compensation.

[0039] The push ring assembly 7 is mainly used to press the dynamic ring seal ring. In addition to ensuring the sealing effect of the dynamic ring seal ring, it also plays a role in transmitting elastic force, so that the buffer compensation mechanism can work in normal cruising.

[0040] O-ring A4, O-ring B14 and O-ring C15 are made of fluororubber, which can prevent O-ring A4, O-ring B14 and O-ring C15 from aging, cracking, hardening and losing elasticity at a high temperature of 130°C, and can still meet the sealing requirements after being subjected to high temperatures.

[0041] The compensation ring assembly 6 is an inlaid structure, and is made of cemented carbide-titanium alloy material; the compensation ring assembly 6 includes an outer metal layer and an inner metal layer, the outer metal layer, i.e., the compensation ring seat material, is titanium alloy, and the inner metal layer, i.e., the compensation ring material, is cemented carbide. Cemented carbide and titanium alloy have higher strength and certain anti-oxidation and corrosion capabilities under high temperature conditions, so that the mechanical seal can operate well under high temperature conditions.

[0042] A throttle ring 3 is provided on one side of the pump chamber 10 near the gland 18, and the throttle ring 3 is connected with the gland 18. Figure 3 As shown, the throttle ring 3 adopts a special-shaped design, and a step is provided on one side along the circumferential direction. The step matches the gland 18, and the throttle ring 3 and the gland 18 are installed by matching the step. The special-shaped design structure of the throttle ring 3 allows the throttle ring 3 to directly match the gland 18, avoiding the use of a clamping ring for fixing, saving installation space, and being convenient and reliable.

[0043] 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.

[0044] Example 1

[0045] Static pressure test: According to the provisions of standard GB / T14211, the static pressure test shall be carried out at 1.25 times the maximum working pressure of the product and the pressure shall be maintained for 15 minutes.

[0046] Test conditions:

[0047] Medium: deionized water (Grade C water);

[0048] Test temperature: room temperature;

[0049] Test pressure: 0.38MPa;

[0050] Acceptance criteria: Mechanical seal leakage ≤5ml / h.

[0051] Example 2

[0052] Operation test: Operation test is carried out after passing the static pressure test.

[0053] Test conditions:

[0054] Medium: deionized water (Grade C water);

[0055] Test temperature: room temperature;

[0056] Test pressure: 0.3MPa;

[0057] Speed: 3000r / min;

[0058] Test time: The test time is 5h.

[0059] Acceptance criteria: Mechanical seal leakage ≤5ml / h.

[0060] Example 3

[0061] The wear identification test is carried out with clean water as the medium and runs for 100 hours.

[0062] Test conditions:

[0063] Test medium: deionized water (Grade C water);

[0064] Test temperature: room temperature;

[0065] Test pressure: 0.3Mpa;

[0066] Speed: 3000r / min;

[0067] Test time: The test time is 100h.

[0068] Benchmark Check

[0069] Measure and record the height of the stationary ring assembly before the wear test;

[0070] Mark four directions, measure the altitude and make a record, and take the average altitude of the four directions.

[0071] Test steps

[0072] Step 1. Correctly install the seal to the test bench and connect the pipeline;

[0073] Step 2: Increase the sealing chamber pressure to 0.3 MPa, increase the test bench speed to 3000 r / min, and run stably for 100 hours under this state.

[0074] Disassembly inspection: measure and record the height of the stationary ring assembly with orientation marks after the wear test;

[0075] Acceptance criteria: The wear of the stationary ring assembly is not greater than 0.01mm.

[0076] All tests passed and met the acceptance criteria.

[0077] 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 low-pressure steam pump, characterized in that: The device comprises: a rotating component and a stationary component, wherein the rotating component rotates together with the pump shaft (11), and the stationary component is connected to the pump chamber (10); the rotating component comprises: a shaft sleeve (2), a compensation ring assembly (6), a push ring assembly (7), and a spring seat (12), wherein the shaft sleeve (2) is fixedly connected to the pump shaft (11); the stationary component comprises: a non-compensating ring (5) and a gland (18), wherein the gland (18) is fixedly connected to the pump chamber (10), and an O-ring C (15) is arranged between the gland (18) and the pump chamber (10); the non-compensating ring (5), the compensation ring assembly (6), and the push ring assembly (7) The compensating ring assembly (6) is mounted on the outer circle of the shaft sleeve (2), the compensating ring assembly (6) is arranged between the push ring assembly (7) and the non-compensating ring (5), the spring seat (12) is located on the side of the push ring assembly (7) away from the compensating ring assembly (6), and a positioning step is provided on the shaft sleeve (2) to determine the position of the spring seat (12); a friction pair is formed between the adjacent end faces of the compensating ring assembly (6) and the non-compensating ring (5) as a sealing surface; an O-ring B (14) is provided between the back side of the compensating ring assembly (6) away from the sealing surface and the push ring assembly (7), and two O-rings A (4) are provided between the non-compensating ring (5) and the pressure cover (18).

2. A mechanical seal device for a low-pressure heater drain pump according to claim 1, characterized in that: The device also includes a spring (8) which is compressed between the push ring assembly (7) and the spring seat (12).

3. A mechanical seal device for a low-pressure steam pump according to claim 2, characterized in that: The spring seat (12) and the push ring assembly (7) are connected in transmission via a transmission screw (13).

4. A mechanical seal device for a low-pressure heater drain pump according to claim 1, characterized in that: The shaft sleeve (2) and the pump shaft (11) are fixedly connected via a locking nut (1).

5. The mechanical seal device for a low-pressure heater drain pump according to claim 1, characterized in that: The gland (18) is fixedly connected to the pump chamber (10) via a nut (16) and a stud (17).

6. The mechanical seal device for a low-pressure heater drain pump according to claim 1, characterized in that: The compensation ring assembly (6) is an inlaid structure, and is made of a hard alloy-titanium alloy material; the compensation ring assembly (6) comprises an outer metal layer and an inner metal layer, the outer metal layer is the compensation ring seat material, and is made of a titanium alloy, and the inner metal layer is the compensation ring material, and is made of a hard alloy.

7. The mechanical seal device for a low-pressure heater drain pump according to claim 1, characterized in that: The non-compensation ring (5) is made of integral graphite material.

8. The mechanical seal device for a low-pressure heater drain pump according to claim 1, characterized in that: The O-ring A (4), O-ring B (14) and O-ring C (15) are made of fluororubber.

9. The mechanical seal device for a low-pressure heater drain pump according to claim 1, characterized in that: A throttling ring (3) is provided on one side of the pump chamber (10) close to the gland (18), and the throttling ring (3) is installed in coordination with the gland (18).

10. A mechanical seal device for a low-pressure heater drain pump according to claim 9, characterized in that: One side of the throttling ring (3) is provided with a step along the circumferential direction, the step matches with the pressure cover (18), and the throttling ring (3) and the pressure cover (18) are installed by matching with the step.

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