Mechanical sealing structure for main moderator pump

Abstract

The invention provides a mechanical sealing structure for a main moderator pump, which comprises a shaft sleeve, a first spring seat is arranged on the shaft sleeve, a first moving ring is arranged in the first spring seat, and the first spring seat drives the first moving ring to rotate; a first static ring is installed on the right side of the first movable ring, a static ring sealing groove is formed in the outer side of the first static ring, and a static ring sealing ring is arranged in the static ring sealing groove. The mechanical seal is long in service life. The shaft sleeve is positioned by the key, locked by the locking ring, and connected with the nut and the screw, so that the mechanical seal has better transmission capability and axial positioning capability.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical seals for a main moderator pump of a nuclear power plant, and in particular to a mechanical seal structure for a main moderator pump. Background Art

[0002] The moderator pump is a nuclear third-stage pump in a nuclear power plant and an important component of the moderator system of a CANDU heavy water reactor. The moderator is used in a thermal neutron reactor to slow down the fast neutrons produced by fission into thermal neutrons, thereby increasing the probability of fission reactions. The medium in the moderator pump is heavy water. In order to keep the moderator at a lower temperature, a moderator main system is set up. It consists of two 100% capacity moderator pumps. The pump transports the moderator to two heat exchangers for cooling and then injects it into the calandria container. Moderator pump working conditions: maximum mechanical seal temperature 149°C; speed 985r / m; pressure 1.65Mpa.

[0003] The mechanical seals currently used in domestic moderator pumps have poor stability and unstable leakage. During major maintenance of the unit, the mechanical seals were disassembled and found to be severely worn inside, which greatly shortened the service life of the mechanical seals. Summary of the invention

[0004] The object of the present invention is to provide a mechanical seal structure for a main moderator pump, which solves the problems of unstable leakage of the mechanical seal of the moderator pump and short service life of the mechanical seal.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A mechanical seal structure for a main moderator pump comprises a shaft sleeve, wherein a first spring seat is provided on the shaft sleeve, a first moving ring is installed in the first spring seat, and the first spring seat drives the first moving ring to rotate; a first stationary ring is installed on the right side of the first moving ring, a stationary ring sealing groove is provided on the outer side of the first stationary ring, and a stationary ring sealing ring is provided in the stationary ring sealing groove.

[0007] As an implementable manner, a rectangular groove is formed on the shaft sleeve, a rectangular key is installed in the rectangular groove, and the shaft sleeve is fastened to the shaft by means of a set screw and the rectangular key, and rotates with the shaft.

[0008] As an implementable manner, a groove is provided in the shaft sleeve, and a shaft sleeve sealing ring is provided in the groove to block a leakage channel between the shaft sleeve and the shaft.

[0009] As an practicable manner, a first key is provided between the shaft sleeve and the first spring seat, and the first spring seat rotates together with the shaft sleeve under the transmission of the first key.

[0010] As an practicable manner, the lug on the first spring seat is inserted into the outer circular groove of the first movable ring, and the first spring seat drives the first movable ring to rotate.

[0011] As an implementable manner, a first spring is provided in the first spring seat, and the first spring is arranged between the first spring seat and the first moving ring.

[0012] As an implementable manner, a push ring is provided on the left side of the first moving ring, and the push ring is interposed between the first spring and the first moving ring.

[0013] As an implementable manner, a first clamping ring is provided between the first spring seat and the first moving ring.

[0014] As an implementable manner, a static ring sealing groove is provided on the outer side of the first static ring, a static ring sealing ring is provided in the static ring sealing groove, and a first anti-rotation pin is provided on the static ring sealing ring.

[0015] As an practicable manner, two sealing structures are arranged on the main moderator pump shaft, and the two sealing structures form a series sealing structure; the first sealing structure includes the first spring seat, the first dynamic ring, the first static ring, and the static ring sealing ring; the second sealing structure includes the second spring seat, the second dynamic ring, the second static ring, and the second static ring sealing ring.

[0016] Compared with the prior art, the mechanical seal structure for the main moderator pump provided by the present invention has the following beneficial effects:

[0017] The mechanical seal of the present invention has a long service life. The shaft sleeve of the present invention is positioned by a key, locked by a locking ring, and connected with a pressure ring and a nut screw, so that the mechanical seal has a good transmission capacity and axial positioning capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of the mechanical seal structure for the main moderator pump provided by the present invention.

[0020] Description of reference numerals:

[0021] 1-sleeve; 2-sleeve sealing ring; 3-first key; 4-first spring seat; 5-first spring; 6-push ring; 7-first dynamic ring; 8-first clamping ring; 9-first static ring; 10-static ring sealing ring; 11-first anti-rotation pin; 12-front pressure cover; 13-second spring seat; 14-second key; 15-second spring; 16-second dynamic ring sealing ring; 17-second dynamic ring; 18-second clamping ring; 19-second static ring; 20-second sealing ring; 21-second anti-rotation pin; 22-rear pressure cover; 23-third sealing ring; 24-petal ring; 25-third anti-rotation pin; 26-positioning plate assembly; 27-positioning block; 28-first bolt; 29-pressure plate; 30-locking ring; 31-second bolt; 32 third spring; 33-connecting bolt; 34-front and rear pressure cover sealing ring 1; 35-front and rear pressure cover sealing ring 2; 36-first dynamic ring sealing ring. DETAILED DESCRIPTION

[0022] The following is further explained in detail through specific implementation methods.

[0023] like Figure 1 As shown, the present invention provides a mechanical seal structure for a main moderator pump, comprising a rotating part structure and a stationary part structure. The sealing structure is a series mechanical seal.

[0024] The rotating part structure includes a sleeve 1, a sleeve sealing ring 2, a first key 3, a first spring seat 4, a first spring 5, a push ring 6, a first moving ring 7, a first clamping ring 8, a locking ring 30, and a second bolt 31.

[0025] A rectangular groove is provided on the sleeve 1, and a rectangular key is installed in the rectangular groove. The sleeve 1 is fastened to the shaft by means of a set screw and a rectangular key, and rotates with the shaft. A groove is provided in the sleeve 1, and a sleeve sealing ring 2 is arranged in the groove to block the leakage channel between the sleeve 1 and the shaft.

[0026] The first spring seat 4 is mounted on the shaft sleeve 1, and a first key 3 is arranged between the shaft sleeve 1 and the first spring seat 4. The first spring seat 4 rotates together with the shaft sleeve 1 under the transmission of the first key 3.

[0027] A first moving ring 7 is installed in the first spring seat 4 , and the lug on the first spring seat 4 is inserted into the outer circular groove of the first moving ring 7 , so that the first spring seat 4 drives the first moving ring 7 to rotate.

[0028] A first spring 5 is provided in the first spring seat 4, and the first spring 5 is arranged between the first spring seat 4 and the first movable ring 7. A push ring 6 is provided on the left side of the first movable ring 7, and the push ring 6 is interposed between the first spring 5 and the first movable ring 7. The first spring 5 is used to elastically squeeze the push ring 6.

[0029] The dynamic ring seal (first dynamic ring seal 36) is located between the inner hole of the first dynamic ring 7 and the outer circle of the shaft sleeve 1 to form a sealing point to prevent leakage.

[0030] A first clamping ring 8 is provided between the first spring seat 4 and the first movable ring 7 . The first clamping ring 8 is used to prevent the first movable ring 7 from falling off and to confine the first movable ring within the first spring seat 4 .

[0031] The locking ring 30 is composed of two parts, a locking ring and a tensioning ring, which are connected to the sleeve 1 by threads. The locking ring and the tensioning ring are connected by a second bolt 31 and are positioned on the shaft by the pressure plate 29, thereby realizing the axial positioning of the mechanical seal on the shaft.

[0032] The structure of the stationary part includes the first stationary ring 9, the first anti-rotation pin 11, the rear pressure cover 22, various seals (stationary ring seal 10, second seal 20, third seal 23, fourth seal 34, fifth seal 35), the petal ring 24, the positioning plate assembly 26, the positioning block 27, the first bolt 28, and the third spring 32.

[0033] The first stationary ring 9 is arranged on the right side of the first moving ring 7. A stationary ring sealing groove is arranged on the outer side of the first stationary ring 9. A stationary ring sealing ring 10 is arranged in the stationary ring sealing groove. A first anti-rotation pin 11 is arranged on the stationary ring sealing ring 10. The first anti-rotation pin 11 is used to prevent the first stationary ring 9 from rotating and to withstand the tangential force brought by the first moving ring 7.

[0034] The front gland 12 and the rear gland 22 are connected by bolts 33 , and a stopper is provided therebetween for positioning. The first stationary ring 9 is pressed by the front gland 12 .

[0035] The third spring 32 acts on the petal ring 24 to increase the floating property of the petal ring 24 and further reduce the leakage. The fourth sealing ring 34 acts between the front and rear glands to seal the transition between the front and rear glands of the F hole. The fifth sealing ring 35 acts between the gland 12 and the cavity to seal the transition between the front gland 12 and the pump cavity at the A hole. The sixth sealing ring 36 acts on the first moving ring 7 and the shaft sleeve 1 to form a sealing point to prevent leakage.

[0036] The above is the primary sealing structure of the mechanical sealing structure for the main moderator pump provided by the present invention. The present invention also provides a secondary sealing structure. The secondary sealing structure is used as an auxiliary structure. An exhaust hole is designed between the primary sealing structure and the secondary sealing structure to reasonably optimize the overall structure. The overall composition of the secondary sealing structure is the same as that of the primary sealing structure, and preferably, the size is also the same.

[0037] The secondary sealing structure includes a second spring seat 13 , a second key 14 , a second spring 15 , a first sealing ring 16 , a second dynamic ring 17 , a second clamping ring 18 , a second static ring 19 , a second sealing ring 20 , and a second anti-rotation pin 21 .

[0038] The front gland 12, the rear gland 22 are connected to the pump housing through stud nuts, and a sealing ring is arranged between the three to block the leakage channel between the front and rear glands and the pump housing; the static ring is installed on the gland and is prevented from rotating by the anti-rotation pin to keep it relatively still with the gland. The static ring sealing ring is located between the gland and the outer circle of the static ring to block the leakage channel between the gland and the static ring.

[0039] Bolts and positioning blocks fix the rotating part and the stationary part, determine the relative position relationship between the two, that is, the working height of the product; at the same time, ensure the relative stillness of the rotating parts and the stationary parts during transportation to ensure product safety.

[0040] The present invention provides a series two-stage sealing structure: the moderator is used in a thermal neutron reactor to slow down the fast neutrons produced by fission into thermal neutrons, thereby increasing the probability of fission reaction; the medium in the main moderator pump is heavy water, and in order to keep its leakage within a controllable range, a two-stage seal is designed, the series structure ensures the sealing performance, ensures the overall sealing effect, and prevents leakage of the moderator.

[0041] like Figure 1 As shown, port B is the flushing port of the primary sealing cavity, and water is injected into the primary sealing cavity to take away the heat generated by the friction between the first dynamic ring 7 and the first static ring 9, thereby reducing the heat generation of the end surface. Port C is the injection water recovery port of the secondary sealing cavity, which is used to collect the injection water of the primary sealing cavity and the secondary sealing cavity.

[0042] Figure 1 In the middle, exhaust hole D: The main moderator pump is a vertical pump, and exhaust becomes a major problem. In the main moderator pump, an exhaust device must be designed and moderator leakage must be prevented, which becomes a major problem. Therefore, it is designed to be a two-stage seal in series, the first stage to achieve sealing, the second stage to assist, and an exhaust hole is designed between the two to reasonably optimize the overall structure. A better sealing effect is achieved. In the entire sealing structure, a flushing liquid recovery port F is designed for recycling and saving resources.

[0043] In addition to the mechanical seal, the present invention is also provided with a backup seal device. If the seal ring breaks and the high-pressure medium flows out, the backup seal ring will also reduce the flow rate to a controllable range. The pressure plate is thick enough to ensure that it will not be damaged and the medium will not spray out to hurt people, further improving the reliability and safety of the mechanical seal.

[0044] In addition to the mechanical seal, the present invention is also provided with a backup seal device. If the seal ring breaks and the high-pressure medium flows out, the backup seal ring will also reduce the flow rate to a controllable range. The pressure plate is thick enough to ensure that it will not be damaged and the medium will not spray out to hurt people, further improving the reliability and safety of the mechanical seal.

[0045] The mechanical seal gland is equipped with an RTD temperature sensor (port A), which can monitor the internal heating of the mechanical seal in real time, detect abnormal working conditions in time and prevent accidents in advance, and ensure that the mechanical seal operates in a good condition.

[0046] The shaft sleeve of the invention adopts key positioning, locking ring locking, and pressure ring connected with nut screw, so that the mechanical seal has better transmission ability and axial positioning ability.

[0047] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A mechanical seal structure for a main moderator pump, characterized in that: The invention comprises a shaft sleeve (1), wherein a first spring seat (4) is provided on the shaft sleeve (1), a first moving ring (7) is installed in the first spring seat (4), and the first spring seat (4) drives the first moving ring (7) to rotate; a first stationary ring (9) is installed on the right side of the first moving ring (7), a stationary ring sealing groove is provided on the outer side of the first stationary ring (9), and a stationary ring sealing ring (10) is provided in the stationary ring sealing groove.

2. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: The shaft sleeve (1) is provided with a rectangular groove, in which a rectangular key is installed. The shaft sleeve (1) is fastened to the shaft by means of a set screw and the rectangular key, and rotates together with the shaft.

3. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: A groove is provided in the shaft sleeve (1), and a shaft sleeve sealing ring (2) is arranged in the groove to block a leakage channel between the shaft sleeve (1) and the shaft.

4. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: A first key (3) is arranged between the shaft sleeve (1) and the first spring seat (4), and the first spring seat (4) rotates together with the shaft sleeve (1) under the transmission of the first key (3).

5. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: The lug on the first spring seat (4) is inserted into the outer circular groove of the first movable ring (7), and the first spring seat (4) drives the first movable ring (7) to rotate.

6. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: A first spring (5) is provided in the first spring seat (4), and the first spring (5) is arranged between the first spring seat (4) and the first moving ring (7).

7. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: A push ring (6) is provided on the left side of the first moving ring (7), and the push ring (6) is interposed between the first spring (5) and the first moving ring (7).

8. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: A first clamping ring (8) is provided between the first spring seat (4) and the first moving ring (7).

9. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: A stationary ring sealing groove is provided on the outer side of the first stationary ring (9), a stationary ring sealing ring (10) is arranged in the stationary ring sealing groove, and a first anti-rotation pin (11) is provided on the stationary ring sealing ring (10).

10. The mechanical seal structure for the main moderator pump according to claim 1, characterized in that: Two sealing structures are arranged on the main moderator pump shaft, and the two sealing structures form a series sealing structure; the first sealing structure comprises the first spring seat (4), the first dynamic ring (7), the first static ring (9), and the static ring sealing ring (10); the second sealing structure comprises a second spring seat (13), a second dynamic ring (17), a second static ring (19), and a second static ring sealing ring (20).

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