Biogas anaerobic digestion fermentation tank

Abstract

The invention discloses a biogas anaerobic digestion fermentation tank, and relates to the technical field of biogas fermentation. The biogas anaerobic digestion fermentation tank comprises a centrosymmetric tank body assembly, the tank body assembly comprises a main tank mechanism, and the main tank mechanism comprises a main tank; centrosymmetric filtering mechanisms are respectively mounted at two ends of the main tank mechanism; the filtering mechanism comprises a cover tank; the cover tank is covered with a filter frame assembly; one side of the end face of the cover tank is fixedly connected with a pipe sleeve in a penetrating mode. The inner wall of the pipe sleeve is provided with internal threads. An air pipe penetrates through and is fixedly connected to the other side of the end surface of the cover tank; a material pipe mechanism is inserted into the pipe sleeve and comprises a material pipe, and the inner end of the material pipe is inserted into the filter frame assembly at the other end and is opposite to the air pipe at the other end; according to the biogas anaerobic digestion fermentation tank, the tank body assembly is driven by the connecting sleeve to swing at a small angle, the stirring plate assembly arranged in the main tank can be matched to stir organic waste liquid, and the gas production rate is increased.

Description

Technical Field

[0001] This invention relates to the field of biogas fermentation technology, specifically to a biogas anaerobic digestion fermenter. Background Technology

[0002] Biogas, as a clean and renewable energy source, converts organic waste (such as agricultural straw, livestock manure, and food processing waste) into biogas (mainly composed of methane and carbon dioxide) through anaerobic digestion technology. This not only achieves waste reduction and harmless treatment but also provides an effective solution to the energy shortage problem. The anaerobic digester is the core equipment of this technology, and its performance directly affects biogas production, organic matter degradation efficiency, and system operational stability.

[0003] Patent CN103540524A discloses an anaerobic biogas digester, comprising a digester. A first and second air-blocking ring are installed on the cylindrical inner wall of the digester. A first riser is installed at the center of a first baffle, forming an inverted funnel-shaped assembly. A second riser is installed at the center of a second baffle, also forming an inverted funnel-shaped assembly. The lower edge of the first baffle overlaps with the first and second air-blocking rings. The first and second baffles, along with the inner wall of the digester, divide the internal space of the digester into two reaction chambers and a sedimentation chamber. A downcomer is nested within the first riser, which is also nested within the second riser. A water distributor is installed at the bottom of the digester. An elastic fiber anaerobic filter is installed between the water distributor and the first baffle. A fermentation liquid outlet is installed at the top of the digester, a slag outlet at the bottom, an exhaust pipe at the top, and a cover plate at the top of the cylindrical digester. By utilizing the self-stirring effect of biogas, the volumetric gas production rate of the fermenter is increased, and the formation of crusts on the top of the fermenter is reduced when using light feedstocks. This invention is applicable to anaerobic fermentation, and is particularly suitable for the anaerobic digestion of light-density fermentation feedstocks.

[0004] The above-mentioned technical solution utilizes the reflux of organic waste gas and liquid in the downcomer to stir the overall organic waste gas and liquid. This stirring method is not very effective when the liquid level in the fermenter is high. At the same time, there is a chance that the fully reacted organic waste gas and liquid will flow back, which can easily cause ineffective repeated reactions of resources, thereby prolonging the reaction time and reducing the fermentation efficiency. Therefore, there is an urgent need for a biogas anaerobic digestion fermenter to solve the above-mentioned problems. Summary of the Invention

[0005] The purpose of this invention is to provide a biogas anaerobic digester to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a biogas anaerobic digester, comprising a centrally symmetrical tank assembly; The tank assembly includes a main tank mechanism, and the main tank mechanism includes a main tank; The main tank mechanism is equipped with centrally symmetrical filter mechanisms at both ends. The filtration mechanism includes a frustum-shaped shroud, the port of which is connected to the port of the main shroud. The canister is covered with a filter frame assembly; A sleeve is fixedly connected through one side of the end face of the canister, and the inner wall of the sleeve is provided with internal threads. An air pipe is fixedly connected through the other side of the end face of the canister; The sleeve is fitted with a material tube mechanism, which includes a material tube. The inner end of the material tube is inserted into the filter frame assembly at the other end and is opposite to the air tube at the other end. An assembly ring mechanism for connection is fitted on the outer side of the joint between the cover tank and the main tank.

[0007] As a preferred embodiment of the present invention, the outer sides of both ends of the main tank are respectively provided with first threaded grooves; The inner wall of the main tank is provided with inclined stirring plate assemblies in an alternating manner. Each stirring plate assembly includes a stirring plate that is fixedly connected to the main tank. The stirring plate has equidistant and uniformly spaced grooves on its surface near the main tank. The stirring plate assembly is distributed around the feed tube mechanism.

[0008] As a preferred technical solution of the present invention, the tank assembly is externally connected to a rotating frame mechanism, the rotating frame mechanism includes a base plate, a column is fixedly connected to one side of the upper surface of the base plate, a motor is fixedly embedded on the column, and an annular sleeve is fixedly connected to the output end of the motor. The outer middle part of the main tank is fixedly connected to the sleeve.

[0009] As a preferred embodiment of the present invention, the filter frame assembly includes a first fiber layer fixedly attached to the inner side of the cover tank, a second fiber layer adapted to be inserted into the main tank port is attached to the port of the first fiber layer, and insertion posts for connection are evenly and equidistantly inserted at the junction of the first fiber layer and the second fiber layer. Two tubes are fixedly attached to the surface of the second fiber layer, one tube corresponding to the sleeve at the same end and the other tube corresponding to the air tube at the same end. The sleeve extends through the first fiber layer.

[0010] The inner end of the air pipe is inserted into the filter frame assembly at the same end, and a second threaded groove is provided on the air pipe on the outside of the cover. The air tube is screwed to a sleeve through a second threaded groove. A receiving plate is provided on the outer end of the air tube, facing the sleeve. A connecting rod located outside the air tube is fixedly connected between the receiving plate and the sleeve at equal and uniform intervals. A connecting rod for coaxially inserting an air tube is fixedly connected to the center of the surface of the receiving plate, and a tube plug adapted to seal the air tube is fixedly connected to the end of the connecting rod.

[0011] The material tube corresponds to the insertion fitting; The material tube is fixedly wound with a first threaded protrusion that is adapted to the internal thread of the screw connection, and the two ends of the first threaded protrusion are respectively provided with a retaining plate for fixing the material tube.

[0012] As a preferred embodiment of the present invention, the assembly ring mechanism includes an assembly ring, one end of which is fixedly fitted with a cover, and the other end of which is fixedly connected with a second threaded protrusion adapted to be screwed into the first threaded groove.

[0013] Compared with the prior art, the beneficial effects of the present invention are: (1) A biogas anaerobic digestion fermenter, in which organic waste liquid is poured in from top to bottom through a feed pipe, and the organic waste liquid is automatically introduced into the filter frame assembly at the bottom under the action of gravity. The newly introduced organic waste liquid is wrapped by the filter frame assembly, thereby reducing the use of pumps in the process of pouring in organic waste liquid and improving the energy efficiency of operation.

[0014] (2) A biogas anaerobic digestion fermenter, wherein organic waste liquid is directly introduced into the filter frame assembly at the lower end through the feed pipe, and the microbial community in the tank assembly gathers in the lower layer of the tank. The organic waste liquid and microbial community are selected together by the filter frame assembly at the lower end, so that the two can fully react and improve the reaction rate.

[0015] (3) A biogas anaerobic digestion fermenter, wherein after the organic waste liquid is continuously introduced, the hydraulic pressure in the filter frame assembly at the lower end increases continuously, thereby filtering out the reacted organic waste gas from the second fiber layer of the filter frame assembly at the lower end, so that it gradually flows into the main tank, thereby retaining large particulate impurities in the organic waste liquid in the filter frame assembly at the lower end, and finally the gas discharged through the gas pipe at the upper end is filtered by the second fiber layer of the filter frame assembly at both ends, thereby improving the purity of the output.

[0016] (4) A biogas anaerobic digestion fermenter, which is centrally symmetrically arranged with tank components, so that shell-like material can be transferred to the lower end of the tank components through a rotating frame mechanism. Through the reaction process of the lower layer of bacteria and organic waste liquid, the shell-like material on the inner wall of the tank components is removed simultaneously, thus removing the shell-like material in a timely and effective manner and reducing the impact of shell formation on the reaction.

[0017] (5) A biogas anaerobic digester, which can switch the opening and closing of the gas pipe and the feed pipe by means of a screw sleeve and a pipe plug connected to the outside of the gas pipe, thereby improving the flexibility of use.

[0018] (6) A biogas anaerobic digestion fermenter, by installing filter mechanisms at both ends of the main tank mechanism, and the filter mechanisms are screwed to the main tank mechanism through the assembly ring mechanism, so that after slag is collected in the filter frame assembly, the filter mechanism can be unscrewed from the main tank mechanism, and then the obliquely inserted column can be pulled out to separate the second fiber layer and the first fiber layer, thereby enabling the filter frame assembly to be thoroughly cleaned, facilitating slag discharge and improving maintenance convenience.

[0019] (7) A biogas anaerobic digestion fermenter, wherein the feed pipe is screwed to the sleeve through the first thread protrusion and the internal thread. Under normal working conditions of the tank assembly, the feed pipe passes through the filter frame assembly at both ends through the pipe fitting. At this time, the feed pipe completes the self-locking of the connection between the main tank mechanism and the filter mechanism, thereby improving the connection stability during operation.

[0020] (8) A biogas anaerobic digestion fermenter, which is driven to rotate by an external rotating frame mechanism of the tank assembly. When the organic waste gas liquid flows into the main tank through the second fiber layer of the filter frame assembly at the lower end, the motor is started and the tank assembly is driven to swing at a small angle through the sleeve. Therefore, it can cooperate with the stirring plate assembly set in the main tank to stir the organic waste liquid, so that it can react fully and improve the gas production rate. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the rotating frame mechanism of the present invention; Figure 3 This is a schematic diagram of the main tank mechanism of the present invention; Figure 4 This is a schematic diagram of the interior of the tank assembly of the present invention; Figure 5 This is a schematic diagram of the filtration mechanism of the present invention; Figure 6 This is a schematic diagram of the trachea of ​​the present invention; Figure 7 This is a schematic diagram of the material tube mechanism of the present invention; Figure 8 This is a schematic diagram of the assembly ring mechanism of the present invention.

[0022] In the diagram: 1. Rotating frame mechanism; 101. Base plate; 102. Column; 103. Motor; 104. Connecting sleeve; 2. Main tank mechanism; 201. Main tank; 202. First threaded groove; 203. Stirring plate; 204. Leakage groove; 3. Filtering mechanism; 301. Cover tank; 302. Tube sleeve; 303. First fiber layer; 304. Second fiber layer; 305. Insert post; 306. Pipe fitting; 307. Internal thread; 308. Air pipe; 309. Second threaded groove; 310. Rotating sleeve; 311. Connecting plate; 312. Connecting rod; 313. Connecting rod; 314. Pipe plug; 4. Material pipe mechanism; 401. Material pipe; 402. First threaded protrusion; 403. Baffle plate; 5. Assembly ring mechanism; 501. Assembly ring; 502. Second threaded protrusion. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example: Please refer to Figure 1 , Figure 3 , Figure 4 , Figure 5 , Figure 7 A biogas anaerobic digester includes a centrally symmetrical tank assembly that can be flipped for use. The tank assembly includes a main tank mechanism 2, and the main tank mechanism 2 includes a main tank 201; The main tank mechanism 2 is equipped with centrally symmetrical filter mechanisms 3 at both ends; The filtration mechanism 3 includes a frustum-shaped cover tank 301, the port of the cover tank 301 being connected to the port of the main tank 201; The 301 tank is covered with a filter frame assembly; A sleeve 302 is fixedly connected through one end face of the cover tank 301, and the inner wall of the sleeve 302 is provided with an internal thread 307. A gas pipe 308 is fixedly connected through the other side of the end face of the canister 301; The sleeve 302 is fitted with a feed tube mechanism 4, which includes a feed tube 401. The inner end of the feed tube 401 is inserted into the filter frame assembly at the other end and is opposite to the air tube 308 at the other end. An assembly ring mechanism 5 for connection is fitted on the outer side of the mating joint between the cover tank 301 and the main tank 201.

[0025] Please see Figure 3 The outer sides of both ends of the main tank 201 are respectively provided with first threaded grooves 202; The inner wall of the main tank 201 is provided with inclined agitator assemblies. Each agitator assembly includes an agitator 203 that is fixedly connected to the main tank 201. The agitator 203 has grooves 204 that are evenly spaced near the surface of the main tank 201. The agitator assembly is distributed around the feed tube mechanism 4.

[0026] Please see Figure 2 The tank assembly is externally connected to a rotating frame mechanism 1. The rotating frame mechanism 1 includes a base plate 101. A column 102 is fixedly connected to one side of the upper surface of the base plate 101. A motor 103 is fixedly embedded on the column 102. An annular sleeve 104 is fixedly connected to the output end of the motor 103. The outer middle part of the main tank 201 is fixedly connected to the sleeve 104.

[0027] Please see Figure 4 , Figure 5 , Figure 6 , Figure 7 The filter frame assembly includes a first fiber layer 303 fixedly attached to the inner side of the cover tank 301, a second fiber layer 304 adapted to be inserted into the port of the main tank 201 at the port of the first fiber layer 303, and insertion posts 305 for connection evenly and at equal intervals at the junction of the first fiber layer 303 and the second fiber layer 304; the insertion posts 305 are inserted obliquely into the second fiber layer 304 and the first fiber layer 303 and are arranged around them, thus forming a connection between the first fiber layer 303 and the second fiber layer 304 during operation, so that the filter frame assembly forms a solid closed space; Two tubes 306 are fixedly attached to the surface of the second fiber layer 304. One tube 306 corresponds to the sleeve 302 at the same end, and the other tube 306 corresponds to the air tube 308 at the same end. The sleeve 302 extends through the first fiber layer 303.

[0028] The inner end of the air tube 308 is inserted into the filter frame assembly at the same end, and a second threaded groove 309 is provided on the air tube 308 on the outside of the cover 301. The air tube 308 is screwed with a sleeve 310 through the second threaded groove 309. A receiving plate 311 is provided on the outer end of the air tube 308, which is directly opposite the sleeve 310. A connecting rod 312 located outside the air tube 308 is fixedly connected between the receiving plate 311 and the sleeve 310 at equal and uniform intervals. A connecting rod 313, which is coaxially inserted into a gas pipe 308, is fixedly connected to the center of the surface of the receiving plate 311. A pipe plug 314 adapted to seal the gas pipe 308 is fixedly connected to the end of the connecting rod 313. During the operation of the tank assembly, the pipe plug 314 of the upper filter mechanism 3 moves out of the gas pipe 308 and simultaneously moves into the corresponding material pipe 401. Thus, it cooperates with the upper gas pipe 308 to exhaust gas while sealing the lower material pipe 401 to prevent leakage. After the tank assembly has fully fermented, the lower gas pipe 308 can be opened by inserting the lower pipe plug 314 into the corresponding material pipe 401. At this time, excess organic waste liquid can be discharged from the lower gas pipe 308.

[0029] Material tube 401 corresponds to connector fitting 306; A first threaded protrusion 402, adapted to a screw thread 307, is fixedly wound around the feed tube 401. Two retaining plates 403, which are fixedly fitted onto the feed tube 401, are respectively provided at both ends of the first threaded protrusion 402. When the outer retaining plate 403 blocks the feed tube 302, the feed tube 401 is inserted into place; when the inner retaining plate 403 blocks the feed tube 302, the feed tube 401 is disassembled. Rotating the feed tube 401, through the screw connection between the first threaded protrusion 402 and the internal thread 307, allows the feed tube 401 to move along the pipe... The sleeve 302 moves up and down, thereby adjusting the depth of the inner port of the material tube 401 inserted into the lower filter frame assembly, as well as the distance between it and the lower air tube 308. When the filter mechanism 3 needs to be disassembled from the main tank mechanism 2, the upper material tube 401 needs to be rotated first so that it moves up to the lower baffle 403 to attach to the sleeve 302. At this time, the lower port of the material tube 401 just moves out of the tube 306 of the lower filter frame assembly, releasing the self-locking, and then the filter mechanism 3 can be rotated freely.

[0030] Please see Figure 8 The assembly ring mechanism 5 includes an assembly ring 501. One end of the assembly ring 501 is fixedly connected to the inner side of the cover 301, and the other end of the assembly ring 501 is fixedly connected to the inner side of the second threaded protrusion 502 that is adapted to the first threaded groove 202.

[0031] The working principle of this invention is as follows: The upper filter mechanism 3 has a material tube mechanism 4 inserted into the sleeve 302. The inner end of the material tube 401 is inserted into the lower filter frame assembly. Therefore, when pouring organic waste liquid, it is poured in from top to bottom through the material tube 401. Under the action of gravity, the organic waste liquid is automatically guided into the lower filter frame assembly. The filter frame assembly wraps the newly introduced organic waste liquid, thereby reducing the use of pumps in pouring organic waste liquid and improving the energy efficiency of operation.

[0032] The organic waste liquid is directly introduced into the filter frame assembly at the lower end through the feed pipe 401. The bacteria in the tank assembly gather in the lower layer of the tank. The filter frame assembly at the lower end selects the organic waste liquid and bacteria together, so that the two can react fully and improve the reaction rate.

[0033] As organic waste liquid is continuously introduced, the hydraulic pressure inside the lower filter frame assembly increases, thereby filtering out the reacted organic waste gas and liquid from the second fiber layer 304 of the lower filter frame assembly, allowing it to gradually flow into the main tank 201. This retains large particulate impurities in the organic waste liquid within the lower filter frame assembly. Finally, the gas discharged through the upper gas pipe 308 is filtered by the second fiber layer 304 of the filter frame assemblies at both ends, improving the purity of the output.

[0034] After the first fermentation, the upper layer of the tank assembly is prone to crust formation. Therefore, by starting the motor 103, the tank assembly is flipped up and down through the sleeve 104. Due to the central symmetrical arrangement of the tank assembly, the crust can be transferred to the lower end of the tank assembly. Through the reaction process of the lower layer of bacteria and organic waste liquid, the crust formed on the inner wall of the tank assembly is removed simultaneously, which removes the crust in a timely and effective manner and reduces the impact of crust formation on the reaction.

[0035] The upper filter mechanism 3 uses a screw-on sleeve 310 and a plug 314 connected to the outside of the air pipe 308. When the upper air pipe 308 is rotated to the inner end of the second threaded groove 309, the plug 314 is directly inserted into the inner end of the lower material pipe 401 to seal it. At this time, the upper air pipe 308 is connected to the inside and outside for exhaust. When the lower filter mechanism 3 air pipe 308 is rotated to the outer end of the second threaded groove 309, the plug 314 is directly inserted into the inner end of the air pipe 308 to seal it. By switching the air pipe 308 open and closed, the on / off state of the air pipe 308 and the material pipe 401 can be flexibly adjusted, improving the flexibility of use.

[0036] By installing filter mechanisms 3 at both ends of the main tank mechanism 2, and by connecting the filter mechanisms 3 to the main tank mechanism 2 via the assembly ring mechanism 5, after slag is collected in the filter frame assembly, the filter mechanism 3 can be unscrewed from the main tank mechanism 2, and the obliquely inserted post 305 can be pulled out to separate the second fiber layer 304 and the first fiber layer 303. This allows for thorough cleaning of the filter frame assembly, facilitates slag discharge, and improves maintenance convenience.

[0037] The feed pipe 401 is screwed to the sleeve 302 via the first threaded protrusion 402 and the internal thread 307. Under normal working conditions of the tank assembly, the feed pipe 401 passes through the filter frame assemblies at both ends via the fitting 306. At this time, the feed pipe 401 completes the self-locking of the connection between the main tank mechanism 2 and the filter mechanism 3, improving the connection stability during operation. When disassembly is required, the self-locking is released by removing the inner end of the feed pipe 401 from the filter frame assembly at the other end.

[0038] The tank assembly is rotated by an external rotating frame mechanism 1. When the organic waste gas liquid flows into the main tank 201 through the second fiber layer 304 of the filter frame assembly at the lower end, the tank assembly is swung at a small angle by starting the motor 103 and the connecting sleeve 104. This allows it to work with the stirring plate assembly set inside the main tank 201 to stir the organic waste liquid, so that it can react fully and increase the gas production rate.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A biogas anaerobic digester, comprising a centrally symmetrical tank assembly; The tank assembly includes a main tank mechanism (2), and the main tank mechanism (2) includes a main tank (201). The main tank mechanism (2) is equipped with a centrally symmetrical filter mechanism (3) at both ends. Its features are: The filtration mechanism (3) includes a frustum-shaped shroud (301), the port of which is connected to the port of the main shroud (201); The canister (301) is covered with a filter frame assembly; A sleeve (302) is fixedly connected through one end face of the cover (301), and the inner wall of the sleeve (302) is provided with an internal thread (307). An air pipe (308) is fixedly connected to the other side of the end face of the canister (301). The sleeve (302) is fitted with a feed tube mechanism (4), which includes a feed tube (401). The inner end of the feed tube (401) is inserted into the filter frame assembly at the other end and is opposite to the air tube (308) at the other end. An assembly ring mechanism (5) for connection is fitted on the outside of the mating point between the cover tank (301) and the main tank (201).

2. The biogas anaerobic digester according to claim 1, characterized in that: The main tank (201) has first threaded grooves (202) on the outer sides of both ends respectively; The inner wall of the main tank (201) is provided with inclined stirring plate assemblies in an alternating manner. Each stirring plate assembly includes a stirring plate (203) that is fixedly connected to the main tank (201). The stirring plate (203) has grooves (204) evenly spaced near the surface of the main tank (201). The stirring plate assembly is distributed around the feed tube mechanism (4).

3. The biogas anaerobic digester according to claim 1, characterized in that: The tank assembly is externally connected to a rotating frame mechanism (1). The rotating frame mechanism (1) includes a base plate (101). A column (102) is fixedly connected to one side of the upper surface of the base plate (101). A motor (103) is fixedly embedded on the column (102). An annular sleeve (104) is fixedly connected to the output end of the motor (103). The outer middle part of the main tank (201) is fixedly connected to the sleeve (104).

4. The biogas anaerobic digester according to claim 1, characterized in that: The filter frame assembly includes a first fiber layer (303) fixedly attached to the inside of the cover tank (301), a second fiber layer (304) adapted to be inserted into the port of the main tank (201) attached to the port of the first fiber layer (303), and insertion posts (305) for connection are evenly and equidistantly inserted at the junction of the first fiber layer (303) and the second fiber layer (304). Two tubes (306) are fixedly attached to the surface of the second fiber layer (304), one of the tubes (306) corresponds to the sleeve (302) at the same end, and the other tube (306) corresponds to the air tube (308) at the same end. The sleeve (302) extends through the first fiber layer (303).

5. The biogas anaerobic digester according to claim 4, characterized in that: The inner end of the air pipe (308) is inserted into the filter frame assembly at the same end, and a second threaded groove (309) is provided on the air pipe (308) on the outside of the cover (301). The air tube (308) is screwed with a sleeve (310) through a second threaded groove (309). A receiving plate (311) is provided on the outer end of the air tube (308) facing the sleeve (310). A connecting rod (312) located outside the air tube (308) is fixedly connected between the receiving plate (311) and the sleeve (310) at equal and uniform intervals. A connecting rod (313) for coaxial insertion of an air tube (308) is fixedly connected to the center of the surface of the receiving plate (311), and a tube plug (314) adapted to seal the air tube (308) is fixedly connected to the end of the connecting rod (313).

6. A biogas anaerobic digester according to claim 5, characterized in that: The feed tube (401) corresponds to the insertion fitting (306); The material tube (401) is fixedly wound with a first threaded protrusion (402) adapted to the screw thread (307), and the two ends of the first threaded protrusion (402) are respectively provided with a baffle (403) for fixing the material tube (401).

7. The biogas anaerobic digester according to claim 2, characterized in that: The assembly ring mechanism (5) includes an assembly ring (501), one end of which is fixedly connected to a cover (301), and the other end of which is fixedly connected to a second threaded protrusion (502) adapted to the first threaded groove (202).

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