Mechanical sealing structure for emergency reactor core cooling pump

Abstract

The invention provides a mechanical sealing structure for an emergency reactor core cooling pump. The mechanical sealing structure comprises a shaft sleeve, a spring seat is arranged on the shaft sleeve, a movable ring is arranged in the spring seat, a static ring is arranged on the right side of the movable ring, an anti-rotating pin is installed on the static ring, and the static ring is prevented from rotating through the anti-rotating pin; a gland is arranged outside the shaft sleeve, a static ring sealing ring is arranged between the gland and the outer circle of the static ring, and a leakage channel between the gland and the static ring is blocked. The mechanical sealing device is simple in structure, high in reliability and capable of meeting the mechanical sealing requirement of the safety injection ECC pump for the pressurized water reactor nuclear power technology.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical seals for ECC pumps, and in particular to a mechanical seal structure for an emergency core cooling pump. Background Art

[0002] In heavy water reactor nuclear power technology, the injection ECC pump has the injection function and residual heat removal function of other nuclear power plant technologies.

[0003] In the injection mode, the injection ECC pump takes water from the internal refueling water tank (IRWST) in the containment (the water intake is equipped with a filter) and injects it into the cold section or hot section of the corresponding reactor coolant system (RCP) loop.

[0004] In the waste heat removal mode, the ECC pump draws water from the hot section of the RCP and then injects the water cooled by the heat exchanger into the cold section of the corresponding RCP loop.

[0005] During the normal shutdown process of the power plant, when the temperature and pressure of the primary circuit drop to below 140℃ and 3.0MPa abs, the ECC pumps of the A and B trains can be put into operation to cool the primary circuit. When the temperature of the reactor coolant drops to 100℃, the ECC pumps of the C train are put into operation to speed up the cooling rate of the primary circuit.

[0006] The ECC pump for pressurized water reactor nuclear power technology requires the mechanical seal to have extremely high reliability, and be able to operate under multiple operating conditions, withstand severe earthquakes and thermal shocks, and operate stably for a long time under cooling water outage and accident conditions. At the same time, the medium of the ECC is boric acid water. During the temperature change process, there may be a problem of boric acid crystallization. If the boric acid crystal enters the spring, it will affect the floatability of the mechanical seal and cause the mechanical seal to not work properly.

[0007] At present, conventional mechanical seals cannot meet the requirements of the special working environment of ECC pumps in pressurized water reactor nuclear power plants. Summary of the invention

[0008] The object of the present invention is to provide a mechanical seal structure for an emergency core cooling pump, which solves the problem that the floatability of the existing mechanical seal is easily obstructed.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] A mechanical seal structure for an emergency core cooling pump comprises a shaft sleeve, a spring seat is arranged on the shaft sleeve, a dynamic ring is arranged in the spring seat, a static ring is arranged on the right side of the dynamic ring, an anti-rotation pin is installed on the static ring, and the static ring is prevented from rotating by the anti-rotation pin; a pressure cover is arranged on the outer side of the shaft sleeve, and a static ring sealing ring is arranged between the pressure cover and the outer circle of the static ring to block the leakage channel between the pressure cover and the static ring.

[0011] As an implementable manner, a groove is opened on the inner side of the shaft sleeve, and a shaft sleeve sealing ring is installed in the groove to block the leakage channel between the shaft sleeve and the shaft.

[0012] As an practicable manner, a key is installed between the shaft sleeve and the spring seat, and the spring seat rotates together with the shaft sleeve under the transmission of the key.

[0013] As an implementable manner, the movable ring is arranged in the spring seat, and the lug on the spring seat is inserted into the outer circular groove of the movable ring to drive the movable ring to rotate.

[0014] As an implementable manner, a clamping ring is provided between the moving ring and the spring seat.

[0015] As an implementable manner, a second spring is provided in the spring seat, and the second spring elastically presses the moving ring.

[0016] As an implementable manner, a dynamic ring sealing ring is provided between the inner hole of the dynamic ring and the outer circle of the shaft sleeve to form a sealing point to prevent leakage.

[0017] As an practicable manner, the gland is connected to the pump casing via stud nuts, and a gland sealing ring is arranged between the two to block the leakage channel between the gland and the pump casing.

[0018] As an implementable method, the first spring is arranged between the pressure cover and the push ring. The pressure cover is provided with a spring hole, which can better prevent the spring from shifting due to vibration and the like. The presence of the spring makes the throttling ring floating, thereby increasing the toughness and reliability of leakage control.

[0019] As an implementable manner, a throttle ring is arranged on the outside of the gland. When the mechanical seal fails, the medium leaks out from the mechanical seal. The throttle ring can control the leakage within an acceptable range within a certain period of time.

[0020] Compared with the prior art, the mechanical seal structure for emergency core cooling pump provided by the present invention has the following advantages:

[0021] Beneficial effects:

[0022] The invention has a simple structure and high reliability and can meet the mechanical seal requirements of the injection ECC pump used in pressurized water reactor nuclear power technology.

[0023] The flushing features of the present invention are as follows: the flushing inlet of the mechanical seal for the ECC pump is passed from the pump cavity through the pressure cover to the outer cylindrical surface of the static ring. Compared with the traditional flushing of only the friction pair, the overall heat dissipation area of ​​the static ring can be increased to the maximum extent; the flushing medium is passed through the outer cylindrical surface of the static ring to a sealing cavity that is larger than that of an ordinary mechanical seal, the flushing cycle effect of the entire mechanical seal is enhanced, and the service life of the mechanical seal is improved.

[0024] Furthermore, the sleeve is designed with an air release groove in the friction pair section, which can make the mechanical seal more convenient to install, avoid possible slight extrusion of components, and make the mechanical seal more reliable during operation.

[0025] In addition to the mechanical seal, there is also 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.

[0026] The mechanical seal gland is equipped with an RTD temperature sensor, which can monitor the internal heating of the mechanical seal in real time, detect abnormal working conditions in time and prevent accidents in advance, ensuring that the mechanical seal operates in a good condition. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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.

[0028] Figure 1 This is a schematic diagram of a mechanical seal structure for an emergency core cooling pump provided by the present invention.

[0029] Description of reference numerals:

[0030] 1-sleeve; 2-sleeve sealing ring; 3-key; 4-push ring; 5-dynamic ring sealing ring; 6-dynamic ring; 7-static ring; 8-anti-rotation pin; 9-pressure cover; 10-pressure cover sealing ring; 11-first spring; 12-throttle ring; 13-first positioning block; 14-first bolt; 15-second bolt; 16-tension ring; 17-second positioning ring; 18-locking ring; 19-stud; 20-nut; 21-pressure plate; 22-tension spring; 23-metal sleeve; 24-static ring sealing ring; 25-retaining ring; 26-second spring; 27-spring seat. DETAILED DESCRIPTION

[0031] The following is further explained in detail through specific implementation methods.

[0032] like Figure 1 As shown, the present invention provides a mechanical seal structure for an emergency core cooling pump, comprising a rotating part structure and a stationary part structure.

[0033] The rotating part structure includes a sleeve 1, a sleeve sealing ring 2, a key 3, a push ring 4, a dynamic ring sealing ring 5, a dynamic ring 6, a second bolt 15, a tensioning ring 16, a positioning ring 17, a locking ring 18, a clamping ring 25, a second spring 26, and a spring seat 27.

[0034] The shaft sleeve 1 is fastened to the shaft by a set screw and rotates with the shaft. A groove is provided on the inner side of the shaft sleeve 1, and a shaft sleeve sealing ring 2 is installed in the groove to block the leakage channel between the shaft sleeve 1 and the shaft.

[0035] The shaft sleeve 1 is designed with an air release groove in the friction pair section, which can make the mechanical seal more convenient to install, avoid possible slight extrusion of parts, and make the mechanical seal more reliable during operation.

[0036] The shaft sleeve 1 is positioned by a key, locked by a nut, and the pressure ring is screwed to the nut, so that the mechanical seal has better transmission capacity and axial positioning capacity.

[0037] The spring seat 27 is installed on the shaft sleeve 1, and a key 3 is installed between the shaft sleeve 1 and the spring seat 27. The spring seat 27 rotates with the shaft sleeve 1 under the transmission of the key 3. The dynamic ring 6 is arranged in the spring seat 27, and the lug on the spring seat 27 is inserted into the outer groove of the dynamic ring 6 to drive the dynamic ring 6 to rotate. A clamping ring 25 is arranged between the dynamic ring 6 and the spring seat 27.

[0038] A second spring 26 is provided in the spring seat 27. The second spring 26 elastically squeezes the dynamic ring 6. The second spring 26 is arranged between the spring seat and the push ring. The spring seat has a spring hole, which can better prevent the spring from shifting due to vibration and the like, thereby increasing the reliability of the compensation element.

[0039] The dynamic ring seal 5 is located between the inner hole of the dynamic ring 6 and the outer circle of the shaft sleeve 1 to form a sealing point to prevent leakage.

[0040] The locking ring 18 is connected to the shaft sleeve 1 through threads, and the locking ring 18 is connected to the tensioning ring 16 through the second bolt 15. The mechanical seal is positioned on the shaft by the positioning ring 17, thereby realizing the axial positioning of the mechanical seal on the shaft.

[0041] The structure of the stationary part includes a stationary ring 7, an anti-rotation pin 8, a gland 9, a gland sealing ring 10, a first spring 11, a throttle ring 12, a first positioning block 13, a first bolt 14, a stud 19, a nut 20, a tension spring 22, a metal sleeve 23, and a stationary ring sealing ring 24.

[0042] The gland 9 is arranged outside the shaft sleeve 1. The gland 9 is connected to the pump housing through stud nuts, and a gland sealing ring 10 is arranged between the two to block the leakage channel between the gland 9 and the pump housing.

[0043] The stationary ring 7 is installed on the gland 9, and the stationary ring 7 is arranged on the right side of the dynamic ring 6 and abuts against the dynamic ring 6. An anti-rotation pin 8 is installed on the stationary ring 7, and the stationary ring 7 is prevented from rotating by the anti-rotation pin 8, and keeps relatively still with the gland 9. The stationary ring sealing ring 24 is located between the gland 9 and the outer circle of the stationary ring 7, blocking the leakage channel between the gland 9 and the stationary ring 7.

[0044] The first spring 11 is arranged between the gland and the push ring. The gland is provided with a spring hole, which can effectively prevent the spring from shifting due to vibration and the like. The presence of the spring makes the throttling ring floatable, thereby increasing the toughness and reliability of leakage control.

[0045] The throttle ring 12 is arranged on the outside of the gland. When the mechanical seal fails, the medium leaks out from the mechanical seal. The throttle ring can control the leakage within an acceptable range within a certain period of time.

[0046] The first bolt 14 and the first positioning block 13 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 part and the stationary part during transportation, ensuring product safety.

[0047] The stud 19 and the nut 20 connect and fix the mechanical seal gland and the pump chamber, so that the mechanical seal, the pump chamber and the gland form a closed cavity.

[0048] The tension spring 22 connects the three-petal throttle ring 12 into a throttle ring as a whole, so that the throttle ring has radial floating property, thereby improving the sealing performance of the throttle ring.

[0049] The metal sleeve 23 is attached to the throttle ring by the elastic force of the spring 23, so that the throttle ring is subjected to uniform spring force.

[0050] The flushing features of the present invention are as follows: the flushing inlet of the mechanical seal for the ECC pump is passed from the pump cavity through the pressure cover to the outer cylindrical surface of the static ring. Compared with the traditional flushing of only the friction pair, the overall heat dissipation area of ​​the static ring can be increased to the maximum extent; the flushing medium is passed through the outer cylindrical surface of the static ring to a sealing cavity that is larger than that of an ordinary mechanical seal, the flushing cycle effect of the entire mechanical seal is enhanced, and the service life of the mechanical seal is improved.

[0051] 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.

[0052] The mechanical seal gland of the present invention is provided with an RTD temperature sensor, which can monitor the heating condition inside the mechanical seal in real time, detect abnormal working conditions in time and prevent the occurrence of accident conditions in advance, and ensure that the mechanical seal operates in a good state.

[0053] 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 an emergency core cooling pump, characterized in that: The invention comprises a shaft sleeve (1), wherein a spring seat (27) is provided on the shaft sleeve (1), a dynamic ring (6) is provided inside the spring seat (27), a static ring (7) is provided on the right side of the dynamic ring (6), an anti-rotation pin (8) is installed on the static ring (7), and the static ring (7) is prevented from rotating by the anti-rotation pin (8); a pressure cover (9) is provided on the outside of the shaft sleeve (1), and a static ring sealing ring (24) is provided between the pressure cover (9) and the outer circle of the static ring (7) to block the leakage channel between the pressure cover (9) and the static ring (7).

2. The mechanical seal structure for emergency core cooling pump according to claim 1, characterized in that: A groove is provided on the inner side of the shaft sleeve (1), and a shaft sleeve sealing ring (2) is installed in the groove to block the leakage channel between the shaft sleeve (1) and the shaft.

3. The mechanical seal structure for emergency core cooling pump according to claim 1, characterized in that: A key (3) is installed between the shaft sleeve (1) and the spring seat (27), and the spring seat (27) rotates together with the shaft sleeve (1) under the transmission of the key (3).

4. The mechanical seal structure for emergency core cooling pump according to claim 1, characterized in that: The movable ring (6) is arranged in the spring seat (27), and the lug on the spring seat (27) is inserted into the outer circular groove of the movable ring (6), thereby driving the movable ring (6) to rotate.

5. The mechanical seal structure for an emergency core cooling pump according to claim 1 or 4, characterized in that: A clamping ring (25) is provided between the moving ring (6) and the spring seat (27).

6. The mechanical seal structure for emergency core cooling pump according to claim 1, characterized in that: A second spring (26) is arranged in the spring seat (27), and the second spring (26) elastically presses the movable ring (6).

7. The mechanical seal structure for an emergency core cooling pump according to claim 1, characterized in that: A dynamic ring sealing ring (5) is provided between the inner hole of the dynamic ring (6) and the outer circle of the shaft sleeve (1) to form a sealing point to prevent leakage.

8. The mechanical seal structure for an emergency core cooling pump according to claim 1, characterized in that: The gland (9) is connected to the pump casing via a stud nut, and a gland sealing ring (10) is arranged between the two to block the leakage channel between the gland (9) and the pump casing.

9. The mechanical seal structure for an emergency core cooling pump according to claim 1, characterized in that: The first spring (11) is arranged between the pressure cover (9) and the push ring (4), and the pressure cover (9) is provided with a spring hole to prevent the spring from shifting due to vibration or the like.

10. The mechanical seal structure for an emergency core cooling pump according to claim 1, characterized in that: The throttle ring (12) is arranged on the outside of the gland (9). When the mechanical seal fails, the medium leaks out from the mechanical seal. The throttle ring can control the leakage within an acceptable range within a certain period of time.

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