Lead-bismuth main pump mechanical seal with zero leakage to the environment and working method

Abstract

The present invention provides a lead-bismuth main pump mechanical seal with zero leakage to the environment and a working method, including: a shaft sleeve, a sealing cavity, a cooling cavity, and a contact sealing assembly; the shaft sleeve is fixedly installed on the main shaft, the contact sealing assembly includes two pairs of friction pairs up and down, each pair of friction pairs is composed of a dynamic ring assembly and a static ring assembly, the sealing cavity is filled with pressurized sealing liquid provided by a liquid storage tank, and a serpentine cooling jacket is arranged in the cooling cavity; in the present invention, the sealing liquid in the sealing cavity does not flow, no complex mechanical seal control system is required, no pump efficiency needs to be set, and the serpentine cooling jacket structure increases the heat exchange area through the serpentine structure, avoiding faults such as overheating and wear; the sealing liquid collected at the upper and lower end sealing leakage outlets enters a special leakage liquid collection tank, preventing inert gas from mixing into the leakage liquid and entering the atmosphere, and preventing the leakage of radioactive media. Even if the sealing surface is damaged, it will not cause the external leakage of radioactive media due to liquid shortage.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical seals, and in particular, to a lead-bismuth main pump mechanical seal with zero leakage to the environment and its working method. Background Art

[0002] The mechanical seal of the lead-bismuth pump is located above the lead-bismuth pump and below the upper bearing. It is used to maintain the sealing function between the pump cavity and the external atmospheric environment.

[0003] The function of the mechanical seal of the lead-bismuth pump is to ensure the sealing between the gas cavity of the pump and the external atmospheric environment during the operation or shutdown of the pump, prevent the leakage of radioactive substances in the pump cavity into the atmospheric environment, and at the same time prevent air from entering the pump cavity. Once the mechanical seal fails to perform the above-mentioned expected functions under the specified working conditions, it will have an extremely serious impact on the nuclear power operation site, and may even lead to unplanned shutdown in severe cases. Currently, the mechanical seal structure adopted in the patented technology is a shaft sleeve, a parking seal ring plus a dry gas seal assembly. The dry gas seal assembly is a face non-contact seal, and its leakage rate is relatively large. This characteristic leads to the need to consume a large amount of gas for the seal to prevent the leakage of radioactive helium gas. At the same time, there is a risk of radioactive gas overflow after the leakage rate increases. Summary of the Invention

[0004] In order to solve the problems in the prior art, the purpose of the present invention is to provide a lead-bismuth main pump mechanical seal with zero leakage to the environment and its working method.

[0005] To achieve the above-mentioned invention purpose, the technical solution of the present invention is as follows:

[0006] A lead-bismuth main pump mechanical seal with zero leakage to the environment includes: a shaft sleeve 12, a sealing cavity outside the shaft sleeve 12, and a cooling cavity 4 outside the sealing cavity; a contact seal assembly inside the sealing cavity;

[0007] The shaft sleeve 12 is fixedly installed on the main shaft, and the main shaft is installed in the lead-bismuth main pump body, and there is radioactive inert gas in the lead-bismuth main pump body;

[0008] The contact seal assembly includes two pairs of friction pairs, upper and lower. Each pair of friction pairs is composed of a moving ring assembly 6 and a stationary ring assembly 7. The lower friction pair is composed of the upper friction surface of the stationary ring assembly 7 and the lower friction surface of the upper moving ring assembly 6, and the upper friction pair is composed of the upper friction surface of the moving ring assembly 6 and the lower friction surface of the upper stationary ring assembly 7. The moving ring assembly 6 is limited up and down on the shaft sleeve 12 by an upper limit ring 15 and a lower limit ring 16 and rotates together with the shaft sleeve 12. The friction surfaces of the stationary ring assembly 7 and the moving ring assembly 6 are closely attached; the sealing cavity is filled with pressurized sealing liquid provided by a liquid storage tank 13. A sealing liquid inlet joint 3 communicating with the sealing cavity is arranged on the lower left side of the sealing cavity, and a sealing cavity exhaust joint 14 communicating with the sealing cavity is arranged on the upper right side; the sealing liquid inlet joint 3 is communicated with the liquid storage tank 13 through a pipeline;

[0009] Inside the cooling cavity 4 are provided: a serpentine cooling jacket 5, the serpentine cooling jacket comprising a plurality of bent sections connected end to end, and the cooling cavity 4 is provided with a coolant; at the upper left side of the cooling cavity 4 is provided a coolant inlet joint 8 communicating with the cooling cavity 4, and at the upper right side is provided a coolant outlet joint 18 communicating with the cooling cavity 4; the coolant inlet joint 8 is connected to the starting end of the serpentine cooling jacket, and the ending end of the serpentine cooling jacket is connected to the coolant outlet joint 18.

[0010] As a preferred embodiment, the upper limit ring 15 and the lower limit ring 16 limit the movement of the dynamic ring assembly 6 up and down through steps.

[0011] As a preferred embodiment, at the upper left side of the sealing cavity is provided an upper sealing leakage outlet 9, and at the lower right side is provided a lower sealing leakage outlet 19. The upper sealing leakage outlet 9 communicates with the friction surfaces of the dynamic ring assembly 6 and the static ring assembly 7 of the upper friction pair, and the lower sealing leakage outlet 19 communicates with the friction surfaces of the dynamic ring assembly 6 and the static ring assembly 7 of the lower friction pair.

[0012] As a preferred embodiment, the upper limit ring 15 and the lower limit ring 16 are fixedly connected by screws 17.

[0013] As a preferred embodiment, the sealing liquid in the sealing cavity is selected from deionized water or oil.

[0014] As a preferred embodiment, the pressure of the sealing liquid in the sealing cavity is always higher than the pressure of the inert gas in the lead-bismuth pump, so that the inert gas does not enter the sealing liquid and does not leak into the atmosphere.

[0015] As a preferred embodiment, the cooling cavity 4 and the serpentine cooling jacket 5 are sealed together by welding.

[0016] As a preferred embodiment, a spring 11 is provided above the static ring assembly 7, and the static ring assembly 7 is kept in close contact with the friction surface of the dynamic ring assembly 6 under the spring force of the spring 11.

[0017] The present invention also provides a working method of the lead-bismuth main pump mechanical seal with zero leakage to the environment as described above, which is:

[0018] The sealed liquid with pressure enters the sealing cavity from the liquid storage tank through the sealing liquid inlet joint 3. When filling the liquid, the liquid overflows from the sealing cavity exhaust joint 14, indicating that all the gas in the sealing cavity has been discharged, and then the sealing cavity exhaust joint 14 can be closed. The upper sealing leakage outlet 9 is the sealing liquid leakage outlet of the upper friction pair, and the lower sealing leakage outlet 19 is the sealing liquid leakage outlet of the lower friction pair. The sealing liquid collected by the upper and lower sealing leakage outlets enters a special leakage liquid collection tank to prevent inert gas from mixing into the leakage liquid and entering the atmosphere, thus preventing the leakage of radioactive media. Even if the sealing component is damaged, it will not cause the leakage of radioactive media due to liquid shortage, because the oil storage tank 13 can timely supplement the sealing liquid to keep the sealing liquid in the sealing cavity in a full state.

[0019] The sealing liquid enters the sealing cavity and between the upper and lower pairs of friction pairs composed of the dynamic ring assembly 6 and the static ring assembly 7, ensuring that the pressure of the sealing liquid is always higher than the pressure of the inert gas in the lead-bismuth pump, so that the inert gas will not enter the sealing liquid and will not leak from the sealing liquid to the atmosphere, ensuring the safety of radioactive substances in the lead-bismuth pump. The static ring assembly slides relatively up and down under the action of the sealing liquid and the spring force, keeping the friction surface in close contact with the dynamic ring assembly 6.

[0020] The serpentine cooling jacket structure 5 increases the heat exchange area through the serpentine structure. The cooling water enters the cavity between the cooling cavity 4 and the serpentine cooling jacket structure 5 through the coolant inlet joint 8, circulates in the middle and then flows out through the coolant outlet joint 18. The cooling cavity 4 and the serpentine cooling jacket structure 5 are sealed by welding to prevent the coolant from leaking.

[0021] The beneficial effects of the present invention are as follows: The present invention uses a double-end face contact type seal to seal the inert gas in the lead-bismuth pump. Since the sealing liquid in the sealing cavity does not flow, a complex mechanical seal control system is not required. Only an external liquid storage tank that can provide sealed liquid with pressure needs to be hung, and a pump efficiency ring does not need to be set. The serpentine cooling jacket structure is designed in the mechanical seal, which increases the heat exchange area through the serpentine structure. Cooling water is introduced into the serpentine cooling jacket for heat exchange to reduce the heat of the end face in the sealing cavity, ensure good sealing operation conditions, and avoid faults such as overheating and wear. The cooling cavity and the serpentine cooling jacket are sealed by welding, eliminating the leakage of cooling water caused by seal failure between the cooling cavity and the serpentine cooling jacket. Even if the sealing component is damaged, it will not cause the leakage of radioactive media due to liquid shortage, because the external oil storage tank can timely supplement the sealing liquid to keep the sealing liquid in the sealing cavity in a full state. Even if the sealing component is damaged and a large amount of sealing liquid leaks, the leaked sealing liquid can smoothly flow into the leakage collection tank through the upper and lower sealing leakage outlets, preventing inert gas from mixing into the leakage liquid and entering the atmosphere, and will not enter the pump cavity, fundamentally avoiding the risk of radioactive gas overflow or internal leakage. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the mechanical seal structure of the lead-bismuth main pump with zero leakage to the environment in the present invention;

[0023] 1 is the parking seal cavity, 2 is the lower end cover, 3 is the sealing liquid inlet joint, 4 is the cooling cavity, 5 is the serpentine cooling jacket, 6 is the dynamic ring assembly, 7 is the static ring assembly, 8 is the coolant inlet joint, 9 is the upper seal leakage outlet, 10 is the shaft sleeve O-ring, 11 is the spring, 12 is the shaft sleeve, 13 is the liquid storage tank, 14 is the seal cavity exhaust joint, 15 is the upper limit ring, 16 is the lower limit ring, 17 is the screw, 18 is the coolant outlet joint, 19 is the lower seal leakage outlet. Specific embodiments

[0024] The following uses specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0025] As Figure 1 shown, this embodiment provides a mechanical seal for a lead-bismuth main pump with zero leakage to the environment, including: a shaft sleeve 12, a seal cavity outside the shaft sleeve 12, and a cooling cavity 4 outside the seal cavity; a contact seal assembly in the seal cavity;

[0026] The shaft sleeve 12 is fixedly installed on the main shaft, and the main shaft is installed in the lead-bismuth main pump body, and there is radioactive inert gas in the lead-bismuth main pump body;

[0027] The contact seal assembly includes two pairs of friction pairs up and down. Each pair of friction pairs is composed of a dynamic ring assembly 6 and a static ring assembly 7. The lower friction pair is composed of the upper friction surface of the static ring assembly 7 and the lower friction surface of the upper dynamic ring assembly 6, and the upper friction pair is composed of the upper friction surface of the dynamic ring assembly 6 and the lower friction surface of the upper static ring assembly 7. The dynamic ring assembly 6 is limited up and down on the shaft sleeve 12 by the upper limit ring 15 and the lower limit ring 16 and rotates together with the shaft sleeve 12. The friction surfaces of the static ring assembly 7 and the dynamic ring assembly 6 are closely attached; the seal cavity is filled with pressurized sealing liquid provided by the liquid storage tank 13. A sealing liquid inlet joint 3 communicating with the seal cavity is arranged on the lower left side of the seal cavity, and a seal cavity exhaust joint 14 communicating with the seal cavity is arranged on the upper right side; the sealing liquid inlet joint 3 is communicated with the liquid storage tank 13 through a pipeline;

[0028] Inside the cooling cavity 4 are provided: a serpentine cooling jacket 5, the serpentine cooling jacket comprising a plurality of bent segments connected end to end, and the cooling cavity 4 is provided with a coolant; at the upper left side of the cooling cavity 4 is provided a coolant inlet joint 8 communicating with the cooling cavity 4, and at the upper right side is provided a coolant outlet joint 18 communicating with the cooling cavity 4; the coolant inlet joint 8 is connected to the starting end of the serpentine cooling jacket, and the ending end of the serpentine cooling jacket is connected to the coolant outlet joint 18.

[0029] In some embodiments, the upper limit ring 15 and the lower limit ring 16 limit the movement of the moving ring assembly 6 up and down through steps.

[0030] In some embodiments, at the upper left side of the sealing cavity is provided an upper end sealing leakage outlet 9, and at the lower right side is provided a lower end sealing leakage outlet 19. The upper end sealing leakage outlet 9 communicates with the friction surfaces of the moving ring assembly 6 and the stationary ring assembly 7 of the upper friction pair, and the lower end sealing leakage outlet 19 communicates with the friction surfaces of the moving ring assembly 6 and the stationary ring assembly 7 of the lower friction pair.

[0031] In some embodiments, the upper limit ring 15 and the lower limit ring 16 are fixedly connected by screws 17.

[0032] In some embodiments, the sealing liquid of the sealing cavity is selected from deionized water or oil.

[0033] In some embodiments, the pressure of the sealing liquid in the sealing cavity is always higher than the pressure of the inert gas in the lead-bismuth pump, so that the inert gas does not enter the sealing liquid and does not leak into the atmosphere.

[0034] In some embodiments, the cooling cavity 4 and the serpentine cooling jacket 5 are sealed together by welding.

[0035] In some embodiments, a spring 11 is provided above the stationary ring assembly 7, and the stationary ring assembly 7 is kept in close contact with the friction surface of the moving ring assembly 6 under the spring force of the spring 11.

[0036] The sealing liquid inlet joint 3 is connected to the lower end cover 2, and below is the parking sealing cavity 1.

[0037] This embodiment provides a working method of the lead-bismuth main pump mechanical seal with zero leakage to the environment, which is as follows:

[0038] A contact sealing assembly composed of upper and lower pairs of friction pairs of the moving ring assembly 6 and the stationary ring assembly 7 is used to seal the inert gas in the lead-bismuth pump;

[0039] The sealed liquid with pressure enters the sealing cavity from the liquid storage tank 13 through the sealing liquid inlet joint 3. When filling the liquid, the overflow of the liquid from the sealing cavity exhaust joint 14 indicates that all the gas in the sealing cavity has been discharged, and then the sealing cavity exhaust joint 14 can be closed. The upper sealing leakage outlet 9 is the leakage outlet of the sealing liquid for the upper friction pair, and the lower sealing leakage outlet 19 is the leakage outlet of the sealing liquid for the lower friction pair. The sealing liquid collected by the upper and lower sealing leakage outlets enters a special leakage liquid collection tank to prevent inert gas from mixing into the leakage liquid and entering the atmosphere, and to prevent the leakage of radioactive media. Even if the sealing component is damaged, it will not cause the leakage of radioactive media due to the lack of liquid, because the oil storage tank 13 can timely supplement the sealing liquid to keep the sealing liquid in the sealing cavity in a full state.

[0040] The sealing liquid enters the sealing cavity and between the upper and lower pairs of friction pairs composed of the dynamic ring assembly 6 and the static ring assembly 7, ensuring that the pressure of the sealing liquid is always higher than the pressure of the inert gas in the lead-bismuth pump, so that the inert gas will not enter the sealing liquid and will not leak into the atmosphere from the sealing liquid, ensuring the safety of the radioactive substances in the lead-bismuth pump. The static ring assembly slides relatively up and down under the action of the sealing liquid and the spring force, keeping the friction surface in close contact with the dynamic ring assembly 6.

[0041] The serpentine cooling jacket structure 5 increases the heat exchange area through the serpentine structure. The cooling water enters the cavity between the cooling cavity 4 and the serpentine cooling jacket structure 5 through the coolant inlet joint 8, circulates in the middle and then flows out through the coolant outlet joint 18. The cooling cavity 4 and the serpentine cooling jacket structure 5 are sealed by welding to prevent the leakage of the coolant.

[0042] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A mechanical seal for a lead-bismuth main pump with zero leakage to the environment, characterized in that, Comprising: A shaft sleeve (12), a sealing cavity outside the shaft sleeve (12), and a cooling cavity (4) outside the sealing cavity; a contact sealing assembly inside the sealing cavity; The shaft sleeve (12) is fixedly installed on the main shaft, the main shaft is installed in the lead-bismuth main pump body, and there is radioactive inert gas in the lead-bismuth main pump body; The contact sealing assembly includes two pairs of upper and lower friction pairs, each friction pair is composed of a dynamic ring assembly (6) and a static ring assembly (7). The lower friction pair is composed of the upper friction surface of the static ring assembly (7) and the lower friction surface of the upper dynamic ring assembly (6). The upper friction pair is composed of the upper friction surface of the dynamic ring assembly (6) and the lower friction surface of the upper static ring assembly (7). The dynamic ring assembly (6) is vertically limited on the shaft sleeve (12) by an upper limit ring (15) and a lower limit ring (16) and rotates together with the shaft sleeve (12). The friction surfaces of the static ring assembly (7) and the dynamic ring assembly (6) are closely attached; the sealing cavity is filled with pressurized sealing liquid provided by a liquid storage tank (13). A sealing liquid inlet joint (3) communicating with the sealing cavity is arranged on the lower left side of the sealing cavity, and a sealing cavity exhaust joint (14) communicating with the sealing cavity is arranged on the upper right side; the sealing liquid inlet joint (3) is communicated with the liquid storage tank (13) through a pipeline; A serpentine cooling jacket (5) is arranged inside the cooling cavity (4). The serpentine cooling jacket includes a plurality of bent sections connected end to end. The cooling cavity (4) is provided with cooling liquid; a cooling liquid inlet joint (8) communicating with the cooling cavity (4) is arranged on the upper left side of the cooling cavity (4), and a cooling liquid outlet joint (18) communicating with the cooling cavity (4) is arranged on the upper right side; the cooling liquid inlet joint (8) is connected to the starting end of the serpentine cooling jacket, and the end of the serpentine cooling jacket is connected to the cooling liquid outlet joint (18); The pressure of the sealing liquid in the sealing cavity is always higher than the pressure of the inert gas in the lead-bismuth pump, and the inert gas does not enter the sealing liquid and does not leak into the atmosphere; A spring (11) is arranged above the static ring assembly (7), and the static ring assembly (7) maintains close contact with the friction surface of the dynamic ring assembly (6) under the spring force of the spring (11).

2. The mechanical seal of the lead-bismuth main pump with zero leakage to the environment according to claim 1, characterized in that: The upper limit ring (15) and the lower limit ring (16) limit the dynamic ring assembly (6) vertically through steps.

3. The mechanical seal of the lead-bismuth main pump with zero leakage to the environment according to claim 1, characterized in that: An upper end sealing leakage outlet (9) is arranged on the upper left side of the sealing cavity, and a lower end sealing leakage outlet (19) is arranged on the lower right side. The upper end sealing leakage outlet (9) communicates with the friction surfaces of the dynamic ring assembly (6) and the static ring assembly (7) of the upper friction pair, and the lower end sealing leakage outlet (19) communicates with the friction surfaces of the dynamic ring assembly (6) and the static ring assembly (7) of the lower friction pair.

4. A mechanical seal for a lead-bismuth main pump with zero leakage to the environment according to claim 1, characterized in that: The upper limit ring (15) and the lower limit ring (16) are fixedly connected by screws (17).

5. A mechanical seal for a lead-bismuth main pump with zero leakage to the environment according to claim 1, characterized in that: The sealing liquid in the sealing cavity is selected from deionized water or oil.

6. The mechanical seal of the lead-bismuth main pump with zero leakage to the environment according to claim 1, characterized in that: The cooling cavity (4) and the serpentine cooling jacket (5) are sealed together by welding.

7. The working method of the lead-bismuth main pump mechanical seal with zero leakage to the environment according to any one of claims 1 to 6, characterized in that: A contact sealing assembly with two pairs of upper and lower friction pairs composed of a dynamic ring assembly (6) and a static ring assembly (7) is used to seal the inert gas in the lead-bismuth pump; The sealed liquid with pressure enters the sealing cavity from the liquid storage tank through the sealing liquid inlet joint (3). When filling the liquid, the overflow of the liquid from the sealing cavity exhaust joint (14) indicates that all the gas in the sealing cavity has been discharged, and then the sealing cavity exhaust joint (14) can be closed; the upper sealing leakage outlet (9) is the sealing liquid leakage outlet of the upper friction pair, and the lower sealing leakage outlet (19) is the sealing liquid leakage outlet of the lower friction pair. The sealing liquid collected by the upper and lower sealing leakage outlets enters a special leakage liquid collection tank to prevent inert gas from mixing into the leakage liquid and entering the atmosphere, and to prevent the leakage of radioactive media; even if the sealing component is damaged, it will not cause the leakage of radioactive media due to the lack of liquid. The liquid storage tank (13) can replenish the sealing liquid in time to keep the sealing liquid in the sealing cavity in a full state; The sealing liquid enters the sealing cavity and between the upper and lower pairs of friction pairs composed of the dynamic ring assembly (6) and the static ring assembly (7), ensuring that the pressure of the sealing liquid is always higher than the pressure of the inert gas in the lead-bismuth pump, so that the inert gas will not enter the sealing liquid and will not leak from the sealing liquid to the atmosphere, ensuring the safety of radioactive substances in the lead-bismuth pump; the static ring assembly slides relatively up and down under the action of the sealing liquid and the spring force, keeping the friction surface in close contact with the dynamic ring assembly (6); The serpentine cooling jacket (5) increases the heat exchange area through the serpentine structure. The cooling water enters the cavity between the cooling cavity (4) and the serpentine cooling jacket (5) through the coolant inlet joint (8), circulates in the middle and then flows out through the coolant outlet joint (18). The cooling cavity (4) and the serpentine cooling jacket (5) are sealed by welding to prevent the leakage of the coolant.

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