Self-drainage system suitable for underground high-pressure gas storage chamber and construction and use method

Abstract

The invention provides a self-drainage system suitable for an underground high-pressure gas storage chamber and a construction and use method. The self-drainage system comprises a steel plugging head, an electric control hydraulic jack used for providing jacking power is arranged under the steel plugging head, and the electric control hydraulic jack is installed in a water collecting tank; a concrete lining is filled between the underground chamber closed cylindrical steel lining and the natural surrounding rock, plugging holes are formed in the positions, where the steel plugging heads are located, of the underground chamber closed cylindrical steel lining and the concrete lining, sealing layers are arranged on the outer surfaces of the plugging holes, and the side face of the bottom of the water collecting tank communicates with a drainage pipeline. The system can effectively discharge condensate water generated by high and low air pressure difference and temperature difference on the premise of ensuring the air tightness of the underground chamber, and is durable, simple to construct and convenient to operate.

Description

Technical Field

[0001] The invention relates to a self-draining system suitable for an underground high-pressure gas storage chamber and a construction and use method thereof, belonging to the technical field of underground high-pressure gas storage chambers. Background Art

[0002] High-pressure gas storage is a new type of energy storage method. Its chamber layout area is usually in the rock layer below 100 meters below the surface. It is subject to extremely high gas pressure, usually 10 to 20 MPa. Therefore, in the work of high-pressure gas storage, particularly high requirements are placed on the sealing of the gas. The deep underground high-pressure gas storage chamber is the core structure of the air compression energy storage system. The airtightness of the underground chamber is the key to the compression system to ensure the energy conversion efficiency of air energy storage. During the operation of the gas storage chamber, the temperature change caused by the high and low air pressure difference in the chamber is between -30℃ and 70℃, so a large amount of condensed water will accumulate in the chamber. However, in the closed and high-pressure environment underground, the condensed water is difficult to flow or evaporate and discharge, and it is also difficult to pump out the condensed water. Summary of the invention

[0003] The purpose of the present invention is to provide a self-draining system suitable for an underground high-pressure gas storage chamber. This system can effectively discharge condensed water generated by high and low pressure differences and temperature differences while ensuring the air tightness of the underground chamber, and is durable, simple to construct, and easy to operate.

[0004] In order to realize the above-mentioned technical features, the purpose of the present invention is achieved as follows: a self-drainage system suitable for an underground high-pressure gas storage chamber, comprising a steel plugging head, an electro-hydraulic jack for providing jacking power is arranged directly below the steel plugging head, and the electro-hydraulic jack is installed and arranged inside the water collection tank; concrete lining is filled between the closed cylindrical steel lining of the underground chamber and the natural surrounding rock, and plugging holes are arranged on the closed cylindrical steel lining of the underground chamber and the concrete lining and at the position of the steel plugging head, and a sealing layer is arranged on the outer surface of the plugging hole, and a drainage pipe is connected to the bottom side of the water collection tank.

[0005] The steel plugging head is prefabricated in a factory using steel materials, and a single piece of the steel plugging head is in a frustum shape.

[0006] Multiple groups of high-performance springs are evenly welded and fixed on the side of the steel plugging head. The high-performance springs are installed inside the spring groove, and the spring groove is arranged inside the concrete lining.

[0007] The axis of the high-performance spring is arranged vertically to the side of the lower truncated cone of the steel plugging head.

[0008] The sealing layer is coated with a high molecular weight butyl rubber material.

[0009] The enclosed cylindrical steel lining of the underground chamber is made of factory prefabricated steel plates spliced ​​on-site, arranged around the chamber, and the steel plates are fully welded.

[0010] The natural surrounding rock is Grade II or Grade I surrounding rock, has no developed cracks, good integrity and high compressive strength.

[0011] The concrete lining is large-area cast-in-place C40 self-compacting concrete.

[0012] A construction method for a self-draining system of an underground high-pressure gas storage chamber comprises the following steps: Step 1: Prefabrication of steel plug and high-performance spring: In the factory, the steel plugging head and the high-performance spring are first processed and formed, and then the steel plugging head and the high-performance spring are welded; Step 2: Prefabrication of the sealed cylindrical steel lining curved steel plate of the underground chamber: In the factory, the steel plates are made into curved steel plates for on-site splicing; one steel plate is reserved as a steel plate for arranging drainage grooves, and the drainage groove holes need to be reserved in this steel plate; Step 3: Excavation of gas storage chamber: A gas storage chamber is excavated in the natural surrounding rock of level II or I, and the chamber is excavated into a tunnel type; after the excavation of the entire chamber is completed, an area for a reserved water collection tank is excavated, and the water collection tank is arranged near the maintenance passage. The water collection tank is first excavated to the depth of the reserved drainage pipe, and is divided into an upper part and a lower part. The upper part of the water collection tank is a truncated cone, and spring grooves are excavated on all four sides after excavation; the pre-buried drainage pipe is located at the bottom of the water collection tank; Step 4: Transportation and installation of the sealed cylindrical steel lining of the underground chamber: Use transportation equipment to transport a single curved steel plate to the site. After all components are transported to the site, first assemble and splice the curved steel plates on site. After multiple curved steel plates are spliced ​​into a cylindrical shape to form the main body of the closed cylindrical steel lining of the underground chamber, full welding is used to fill all the welds between the curved steel plates to ensure the airtightness of the closed cylindrical steel lining of the underground chamber; in the water collection tank layout area, the reserved drainage trough holes of the steel plate must be aligned with the holes drilled in the water collection tank; Step 5: Concrete lining pouring and drainage pipe laying: After the arc-shaped steel plate is welded, a closed cylindrical steel lining of the underground chamber is formed. The self-compacting concrete is poured layer by layer on the outer side of the closed cylindrical steel lining of the underground chamber in the order of lower layer first and upper layer later, so that the steel mesh is buried in the concrete lining, and the space between the closed cylindrical steel lining of the underground chamber and the concrete layer is fully filled, so that the concrete layer can evenly transfer the load; Step 6: Installation of steel plugging head: After the concrete lining is poured, an electric-controlled hydraulic jack is arranged at the bottom of the water collection tank to align the lifting platform of the electric-controlled hydraulic jack with the bottom surface of the steel plugging head. At the same time, plain concrete is poured in the reserved spring groove. The tail of the high-performance spring is buried in the plain concrete before the initial setting of the concrete. After the final setting of the concrete, the high-performance spring is flexibly connected to the natural surrounding rock. Step 7: Setting of sealing layer: After the high-performance springs are installed, epoxy resin primer and butyl rubber sealing strips are used to bond the closed cylindrical steel lining and concrete lining sides of the underground chamber to form a sealing layer to ensure the airtightness of the drainage system when it is not opened.

[0013] A method for using a self-draining system for an underground high-pressure gas storage chamber comprises the following steps: Use of electronically controlled hydraulic jack: The drainage system controls the opening and closing of the plugging hole by lifting and lowering the electric-controlled hydraulic jack. The electric control system of the electric-controlled hydraulic jack is set in the maintenance channel. The maintenance staff controls the electric-controlled hydraulic jack to lift and open the plugging hole. During the opening of the plugging hole, the condensed water will be discharged by itself due to the pressure difference between the air pressure in the gas storage chamber and the outside air pressure. After no water is discharged, the maintenance staff controls the electric-controlled hydraulic jack to lower the steel plugging head and close the plugging hole. Drainage system service life: The drainage system requires maintenance personnel to drain condensate once a month; Drainage system use conditions: During the operation of the underground gas storage chamber, the air pressure in the chamber circulates between 10-20MPa, and the drainage system is opened when the air pressure in the chamber reaches 10~14MPa.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention drains water by itself through the pressure difference between the chamber space and the outside world, effectively solving the drainage problem in the high-pressure environment of the underground gas storage chamber, increasing the actual storage capacity of the chamber, and indirectly improving the energy storage efficiency.

[0015] 2. The present invention effectively ensures the air tightness of the chamber whether in the drainage process or in the non-drainage period by arranging steel plugging heads and polymer materials.

[0016] 3. The present invention uses an electronically controlled hydraulic jack to select the drainage time, which is simple to operate and convenient to use.

[0017] 4. The present invention ensures its structural strength and stability through the above-mentioned steel plugging head.

[0018] 5. Multiple sets of high-performance springs can be used to provide elastic support for the steel plugging head.

[0019] 6. Due to the large area of ​​the underground chamber, it is necessary to pour it in batches and sections to prevent local void areas from occurring in the concrete lining. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below.

[0021] Figure 1 It is a schematic diagram of the overall structure of the high-pressure gas storage chamber of the present invention.

[0022] Figure 2 The present invention Figure 1 Medium AA view.

[0023] Figure 3 The present invention Figure 1 Medium BB view.

[0024] In the figure: high-performance spring 1, electric-controlled hydraulic jack 2, steel plugging head 3, underground chamber closed cylindrical steel lining 4, concrete lining 5, spring groove 6, sealing layer 7, natural surrounding rock 8, drainage pipe 9, plugging hole 10, and water collection tank 11. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Embodiment 1: See also Figure 1-3, a self-drainage system for underground high-pressure gas storage chambers, including a steel plugging head 3, an electric-controlled hydraulic jack 2 for providing jacking power is arranged directly below the steel plugging head 3, and the inside of the water collection tank 11 where the electric-controlled hydraulic jack 2 is installed; a concrete lining 5 is filled between the closed cylindrical steel lining 4 of the underground chamber and the natural surrounding rock 8, and a plugging hole 10 is arranged on the closed cylindrical steel lining 4 and the concrete lining 5 of the underground chamber and located at the position of the steel plugging head 3, and a sealing layer 7 is arranged on the outer surface of the plugging hole 10, and a drainage pipe 9 is connected to the bottom side of the water collection tank 11. This system can effectively discharge condensed water generated by high and low pressure differences and temperature differences while ensuring the airtightness of the underground chamber, and is durable, simple to construct, and convenient to operate. During specific use, when condensed water needs to be discharged, the opening or closing of the steel plugging head 3 is controlled by the electrically controlled hydraulic jack 2 to discharge the collected water inside the closed cylindrical steel lining 4 of the underground chamber from the plugging hole 10 to the water collecting tank 11, and then discharged from the water collecting tank 11 and the drainage pipe 9.

[0027] Furthermore, the steel plugging head 3 is prefabricated in a factory using steel materials, and a single steel plugging head 3 is in a truncated cone shape. The steel plugging head 3 ensures its structural strength and stability.

[0028] Preferably, the steel plugging head 3 has an upper bottom surface diameter of 1000 mm, a lower bottom surface diameter of 500 mm, and a height of 350 mm.

[0029] Furthermore, multiple groups of high-performance springs 1 are uniformly welded and fixed to the side of the steel plugging head 3, and the high-performance springs 1 are installed inside the spring groove 6, and the spring groove 6 is arranged inside the concrete lining 5. The multiple groups of high-performance springs 1 can be used to elastically support the steel plugging head 3.

[0030] Preferably, the high performance spring 1 is 300 mm long.

[0031] Furthermore, the axis of the high-performance spring 1 is arranged vertically to the side of the lower cone of the steel plugging head 3 .

[0032] Preferably, the specification of the electronically controlled hydraulic jack 2 is an 80t small hydraulic jack.

[0033] Furthermore, the sealing layer 7 is coated with a high molecular weight butyl rubber material. The sealing strip is glued to the side of the closed cylindrical steel lining 4 and the concrete lining 5 of the underground chamber with an epoxy resin primer, and the thickness is 25 mm.

[0034] Furthermore, the enclosed cylindrical steel lining 4 of the underground chamber is formed by on-site splicing of prefabricated steel plates in the factory, arranged around the chamber, and the steel plates are fully welded.

[0035] Preferably, an arc-shaped steel plate with a length of 7 meters, a width of 3 meters and a thickness of 15 millimeters is used to make a closed cylindrical steel lining 4 of the underground chamber.

[0036] Furthermore, the natural surrounding rock 8 is Grade II or I surrounding rock, has no developed cracks, good integrity and high compressive strength.

[0037] Furthermore, the concrete lining 5 is a large area cast-in-place C40 self-compacting concrete, and uses pozzolan cement with good air tightness.

[0038] Preferably, the concrete lining 5 needs to be provided with transverse and longitudinal steel bars, and when pouring, it is necessary to ensure that the space between the closed cylindrical steel lining 4 of the underground chamber and the natural surrounding rock 8 is fully filled to ensure that the concrete lining 5 can evenly transfer the load, thereby well ensuring the structural stability of the closed cylindrical steel lining 4 of the underground chamber. Furthermore, due to the large area of ​​the underground chamber, it is necessary to pour in batches and sections to prevent the occurrence of local empty areas in the concrete lining 5.

[0039] Preferably, the longitudinal reinforcement and the transverse reinforcement inside the concrete lining 5 are arranged in φ18@250.

[0040] Preferably, a water collection trough needs to be arranged at the bottom of the concrete lining 5. The water collection trough is arranged at the outermost part of the underground chamber, a closed cylindrical steel lining 4 of the underground chamber, and is close to the bottom in the direction of the construction access road. The water collection trough holes of the arc-shaped steel plate are reserved during prefabrication in the factory.

[0041] Preferably, the drainage pipe 9 is embedded in the concrete lining 5 before concrete pouring, and the diameter of the drainage pipe 9 is 50 mm.

[0042] Embodiment 2: A construction method for a self-draining system of an underground high-pressure gas storage chamber comprises the following steps: Step 1: Prefabrication of the steel plug 3 and the high-performance spring 1: In the factory, the steel plugging head 3 and the high-performance spring 1 are first processed and formed, and then the steel plugging head 3 and the high-performance spring 1 are welded; Step 2: Prefabrication of the sealed cylindrical steel lining and 4 curved steel plates of the underground chamber: In the factory, the steel plates are made into curved steel plates for on-site splicing; one steel plate is reserved as a steel plate for arranging drainage grooves, and the drainage groove holes need to be reserved in this steel plate; Step 3: Excavation of gas storage chamber: A gas storage chamber is excavated in the natural surrounding rock 8 of level II or I, and the chamber is excavated into a tunnel type; after the excavation of the entire chamber is completed, an area for a reserved water collection tank 11 is excavated, and the water collection tank 11 is arranged near the maintenance passage. The water collection tank is first excavated to the depth of the reserved drainage pipe 9, and is divided into an upper part and a lower part. The upper part of the water collection tank is a truncated cone, and after excavation, spring grooves 6 are continuously excavated on all sides; the pre-buried drainage pipe 9 is located at the bottom of the water collection tank 11; Step 4: Transportation and installation of the closed cylindrical steel lining 4 of the underground chamber: A single curved steel plate is transported to the site by transport equipment. After all components are transported to the site, the curved steel plates are first assembled and spliced ​​on site. After multiple curved steel plates are spliced ​​into a cylindrical shape to form the main body of the closed cylindrical steel lining 4 of the underground chamber, the welds between the curved steel plates are fully welded to ensure the air tightness of the closed cylindrical steel lining 4 of the underground chamber; in the area where the water collection tank 11 is laid, the reserved drainage trough holes of the steel plate need to be aligned with the holes drilled in the water collection tank; Step 5: pouring of concrete lining 5 and laying of drainage pipes: After the arc-shaped steel plate is welded, the closed cylindrical steel lining 4 of the underground chamber is formed. The self-compacting concrete is poured layer by layer on the outer side of the closed cylindrical steel lining 4 of the underground chamber in the order of the lower layer first and the upper layer later, so that the steel mesh is buried in the concrete lining 5, and it is ensured that the space between the closed cylindrical steel lining 4 of the underground chamber and the concrete layer is fully filled, so that the concrete layer can evenly transfer the load; Step 6: Installation of steel plugging head 3: After the concrete lining 5 is poured, the electric-controlled hydraulic jack 2 is arranged at the bottom of the water collection tank 11, so that the lifting platform of the electric-controlled hydraulic jack 2 is aligned with the lower bottom surface of the steel plugging head 3, and at the same time, plain concrete is poured in the reserved spring groove 6, and the tail of the high-performance spring 1 is buried in the plain concrete before the concrete is initially set, and the high-performance spring 1 is flexibly connected to the natural surrounding rock 8 after the concrete is finally set; Step 7: Setting of sealing layer 7: After the high-performance spring 1 is installed, epoxy resin primer and butyl rubber sealing strip are used to bond the closed cylindrical steel lining 4 and the concrete lining 5 of the underground chamber to form a sealing layer 7 to ensure the airtightness of the drainage system when it is not opened.

[0043] Embodiment 3: A method for using a self-draining system for an underground high-pressure gas storage chamber comprises the following steps: Use of electronically controlled hydraulic jack 2: The drainage system controls the opening and closing of the plugging hole by lifting and lowering the electric-controlled hydraulic jack 2. The electric control system of the electric-controlled hydraulic jack 2 is set in the maintenance channel. The maintenance staff controls the electric-controlled hydraulic jack 2 to lift and open the plugging hole 10. During the opening of the plugging hole, the condensed water will be discharged by itself due to the difference in air pressure in the gas storage chamber and the outside air pressure. After no water is discharged, the maintenance staff controls the electric-controlled hydraulic jack 2 to lower the steel plugging head 3, and the plugging hole is closed; Drainage system service life: The drainage system requires maintenance personnel to drain condensate once a month; Drainage system use conditions: During the operation of the underground gas storage chamber, the air pressure in the chamber circulates between 10-20MPa, and the drainage system is opened when the air pressure in the chamber reaches 10~14MPa.

[0044] By opening the valve when the air pressure in the chamber is relatively low, the opening pressure is reduced, thereby extending the service life.

[0045] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A self-drainage system for underground high-pressure gas storage chambers, characterized in that: The invention comprises a steel plugging head (3), an electric-controlled hydraulic jack (2) for providing lifting power is arranged directly below the steel plugging head (3), and the electric-controlled hydraulic jack (2) is installed inside a water collecting tank (11); a concrete lining (5) is filled between a closed cylindrical steel lining (4) of the underground chamber and a natural surrounding rock (8); a plugging hole (10) is arranged on the closed cylindrical steel lining (4) of the underground chamber and the concrete lining (5) and located at the position of the steel plugging head (3); a sealing layer (7) is arranged on the outer surface of the plugging hole (10); and a drainage pipe (9) is connected to the bottom side of the water collecting tank (11).

2. A self-drainage system for underground high-pressure gas storage chambers according to claim 1, characterized in that: The steel plugging head (3) is prefabricated in a factory using steel materials, and a single piece of the steel plugging head (3) is in the shape of a truncated cone.

3. A self-drainage system for underground high-pressure gas storage chambers according to claim 2, characterized in that: Multiple groups of high-performance springs (1) are uniformly welded and fixed to the side of the steel plugging head (3); the high-performance springs (1) are installed inside the spring groove (6); and the spring groove (6) is arranged inside the concrete lining (5).

4. A self-drainage system for underground high-pressure gas storage chambers according to claim 3, characterized in that: The axis of the high-performance spring (1) is arranged vertically to the side of the lower truncated cone of the steel plugging head (3).

5. The self-drainage system for underground high-pressure gas storage chamber according to claim 3 is characterized in that: The sealing layer (7) is coated with a high molecular weight butyl rubber material.

6. The self-drainage system for underground high-pressure gas storage chamber according to claim 3, characterized in that: The sealed cylindrical steel lining (4) of the underground chamber is made of factory prefabricated steel plates spliced ​​on site and arranged around the chamber, with the steel plates fully welded.

7. The self-drainage system for underground high-pressure gas storage chamber according to claim 3, characterized in that: The natural surrounding rock (8) is of Class II or Class I, has no developed cracks, good integrity and high compressive strength.

8. The self-drainage system for underground high-pressure gas storage chamber according to claim 3, characterized in that: The concrete lining (5) is large-area cast-in-place C40 self-compacting concrete.

9. A construction method for a self-drainage system of an underground high-pressure gas storage chamber as claimed in any one of claims 4 to 8, characterized in that: The following steps are involved: Step 1: Prefabrication of the steel plug (3) and the high-performance spring (1): In a factory, the steel plugging head (3) and the high-performance spring (1) are first processed and formed, and then the steel plugging head (3) and the high-performance spring (1) are welded; Step 2: Prefabrication of the arc-shaped steel plate of the sealed cylindrical steel lining (4) of the underground chamber: In the factory, the steel plates are made into curved steel plates for on-site splicing; one steel plate is reserved as a steel plate for arranging drainage grooves, and the drainage groove holes need to be reserved in this steel plate; Step 3: Excavation of gas storage chamber: A gas storage chamber is excavated in the natural surrounding rock (8) of level II or I, and the chamber is excavated into a tunnel type; after the excavation of the entire chamber is completed, an area for a reserved water collection tank (11) is excavated, and the water collection tank (11) is arranged near the maintenance passage. The water collection tank is first excavated to the depth of the reserved drainage pipe (9), and is divided into an upper part and a lower part. The upper part of the water collection tank is in a truncated cone shape. After excavation, spring grooves (6) are further excavated on all four sides; the pre-buried drainage pipe (9) is located at the bottom of the water collection tank (11); Step 4: Transportation and installation of the sealed cylindrical steel lining (4) of the underground chamber: A single curved steel plate is transported to the site using transport equipment. After all components are transported to the site, the curved steel plates are first assembled and spliced ​​on site. After multiple curved steel plates are spliced ​​into a cylindrical shape to form the main body of the sealed cylindrical steel lining (4) of the underground chamber, the welds between the curved steel plates are fully welded to ensure the airtightness of the sealed cylindrical steel lining (4) of the underground chamber. In the area where the water collection tank (11) is arranged, the drainage trough holes reserved in the steel plate need to be aligned with the holes drilled in the water collection tank. Step 5: Casting of concrete lining (5) and laying of drainage pipes: After the arc-shaped steel plate is welded, a closed cylindrical steel lining (4) of the underground chamber is formed. Self-compacting concrete is poured layer by layer on the outer side of the closed cylindrical steel lining (4) of the underground chamber in the order of first the lower layer and then the upper layer, so that the steel mesh is buried in the concrete lining (5), and it is ensured that the space between the closed cylindrical steel lining (4) of the underground chamber and the concrete layer is fully filled, so that the concrete layer can evenly transfer the load; Step 6: Installation of steel plug (3): After the concrete lining (5) is poured, an electric-controlled hydraulic jack (2) is arranged at the bottom of the water collecting tank (11), so that the lifting platform of the electric-controlled hydraulic jack (2) is aligned with the lower bottom surface of the steel plugging head (3), and at the same time, plain concrete is poured in the reserved spring groove (6), and the tail of the high-performance spring (1) is buried in the plain concrete before the concrete is initially set, and after the concrete is finally set, the high-performance spring (1) is flexibly connected to the natural surrounding rock (8); Step 7: Setting of sealing layer (7): After the high-performance spring (1) is installed, an epoxy resin primer and a butyl rubber sealing strip are used to bond the closed cylindrical steel lining (4) and the concrete lining (5) of the underground chamber to form a sealing layer (7) to ensure the airtightness of the drainage system when it is not opened.

10. A method for using a self-draining system for an underground high-pressure gas storage chamber as claimed in any one of claims 4 to 8, characterized in that: The following steps are involved: Use of the electro-hydraulic jack (2): The drainage system controls the opening and closing of the plugging hole by lifting and lowering the electric-controlled hydraulic jack (2). The electric control system of the electric-controlled hydraulic jack (2) is arranged in the maintenance passage. The maintenance staff controls the electric-controlled hydraulic jack (2) to lift and open the plugging hole (10). During the opening of the plugging hole, condensed water will be discharged automatically due to the difference between the air pressure in the gas storage chamber and the air pressure outside. After no water is discharged, the maintenance staff controls the electric-controlled hydraulic jack (2) to lower the steel plugging head (3), and the plugging hole is closed. Drainage system service life: The drainage system requires maintenance personnel to drain condensate once a month; Drainage system use conditions: During the operation of the underground gas storage chamber, the air pressure in the chamber circulates between 10-20MPa, and the drainage system is opened when the air pressure in the chamber reaches 10~14MPa.

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