An inertable low-temperature caisson device and its piping system

Abstract

The present invention discloses an inertable low-temperature caisson device and its piping system, which relate to the technical field of ship equipment. By setting a caisson assembly, the opening and closing of the upper bottom plate and the lower bottom plate can be controlled by adjusting the screw and the nut, and the caisson shell is isolated from the fuel tank. The trapezoidal sealing cone cooperates with the sealing cone groove to further ensure the isolation and sealing effect. The structure is simple, conducive to processing and production, economical, and has high versatility. The caisson assembly is used to protect the pump body inside it. The caisson assembly includes a caisson shell arranged inside the fuel tank, an upper bottom plate is arranged at one end of the caisson shell, a lower sealing plate is arranged at the other end of the caisson shell, a lower bottom plate is arranged at the bottom of the upper bottom plate, an upper sealing plate for installing an upper component is arranged at the top of the lower sealing plate, and a screw is arranged at the top of the lower bottom plate, the top of which passes through the upper bottom plate, the lower sealing plate and the upper sealing plate in sequence and extends to the top of the upper sealing plate.

Description

Technical Field

[0001] The invention relates to the technical field of ship equipment, in particular to an inertable low-temperature caisson device and a piping system thereof. Background Art

[0002] LPG (liquefied petroleum gas) / LNG (liquefied natural gas) powered ships are also called liquefied petroleum gas powered ships / liquefied natural gas ships. On LPG / LNG powered ships, the fuel is transported from the fuel tank to the main engine by a cryogenic pump. The cryogenic pump is installed in the tank. In order to protect the cryogenic pump, a caisson is installed inside the fuel tank. The cryogenic pump is installed in the caisson, and the suction port is located at the bottom. However, the current caisson device still has the following shortcomings when in use:

[0003] The bottom of a conventional caisson is open and connected to the fuel tank. It can only be maintained after being inerted together with the tank body. The internal space of the caisson is a dead corner. During inerting, LPG / LNG vapor is likely to remain, causing combustion and explosion hazards and potential accidents. It can no longer meet the use requirements. Summary of the invention

[0004] To achieve the above object, the present invention provides the following technical solution: an inertable low-temperature caisson device and a piping system thereof, comprising:

[0005] A caisson assembly is used to protect the pump body inside the caisson assembly, the caisson assembly includes a caisson shell arranged inside the fuel tank, an upper bottom plate is arranged at one end of the caisson shell, a lower sealing plate is arranged at the other end of the caisson shell, a lower bottom plate is arranged at the bottom of the upper bottom plate, an upper sealing plate for mounting an upper component is arranged at the top of the lower sealing plate, a screw rod is arranged at the top of the lower bottom plate, the top end of which sequentially penetrates the upper bottom plate, the lower sealing plate and the upper sealing plate and extends to the top of the upper sealing plate, and the screw rod is used to adjust the distance between the upper bottom plate and the lower bottom plate;

[0006] A trapezoidal sealing cone is provided on the top of the lower base plate, and the top of the trapezoidal sealing cone extends to the interior of the upper base plate to block the connection between the caisson shell and the pump body and the fuel tank. When the lower base plate drives the trapezoidal sealing cone to separate from the interior of the upper base plate, the connection between the caisson shell and the pump body and the fuel tank is achieved. An air inlet cavity connected to the interior of the caisson shell is opened in the interior of the lower sealing plate for receiving the gas inside the inerting caisson shell and the pump body.

[0007] As a preferred technical solution of the present invention, a sealing cone groove matching the trapezoidal sealing cone is provided at the bottom of the lower base plate, the top of the trapezoidal sealing cone extends to the interior of the sealing cone groove, and the sides of the trapezoidal sealing cone and the sealing cone groove are consistent with the horizon angle, and the angle range is between 55° and 65°.

[0008] As a preferred technical solution of the present invention, the surface of the screw rod has threads only at one end located at the upper sealing plate and the threads are connected with a nut, and the screw rod can be lowered or lifted by rotating the nut.

[0009] As a preferred technical solution of the present invention, the pump body is arranged inside the caisson shell, a pump shaft is arranged inside the pump body and a pump impeller is arranged on the surface of the pump shaft.

[0010] As a preferred technical solution of the present invention, the diameter of the screw is between 6mm and 15mm, a through hole is provided inside the upper base plate for sleeve connection with the surface of the screw, and a gap between the through hole and the screw is between 2mm and 6mm.

[0011] As a preferred technical solution of the present invention, the bottom of the lower sealing plate is fixedly connected to the top of the fuel tank, a sealing ring is provided inside the lower sealing plate, and the inside of the sealing ring is movably connected to the surface of the screw to achieve sealing between the lower sealing plate and the fuel tank.

[0012] As a preferred technical solution of the present invention, an upper component is provided on the top of the upper sealing plate by bolts for lifting the pump body in cooperation with lifting equipment. One end of the pump body passes through the outside of the upper component and is provided with a pump outlet flange.

[0013] A piping system capable of inerting a cryogenic caisson device comprises a caisson external piping system for inerting a fuel tank and a caisson inlet piping system for inerting a caisson shell and a pump body, wherein the caisson external piping system comprises an exhaust system, an air return system and an air intake system;

[0014] The exhaust system comprises a valve 1, a valve 2 and a ventilating mast which are sequentially connected through a pipeline, and the valve 1 is connected to the pump outlet flange through a flange;

[0015] The air return system comprises valve 3, valve 4 and an air return pipe which are sequentially connected through pipelines, and valve 3 is connected to valve 1 and valve 2 through pipelines;

[0016] The air intake system includes a one-way valve 1, a valve 5, an air intake pipe and a valve 6 which are sequentially connected through pipelines. The one-way valve 1 is connected to valves 3 and 4 through pipelines.

[0017] As a preferred technical solution of the present invention, the valve six is ​​connected to the interior of the fuel tank through a connecting pipe, and the caisson inlet pipeline system includes a valve seven, a one-way valve two, a pressure regulator and a nitrogen bottle which are sequentially connected through pipelines.

[0018] As a preferred technical solution of the present invention, the valve seven is connected to the air inlet cavity through a pipeline. When the nitrogen bottle transports nitrogen into the caisson shell and the inside of the pump body through the air inlet cavity, the pressure regulator regulates the pressure of the flowing nitrogen.

[0019] Compared with the prior art, the present invention provides an inertable cryogenic caisson device and its piping system, which has the following beneficial effects:

[0020] 1. The inertable low-temperature caisson device and its piping system, by setting up the caisson assembly, can control the opening and closing of the upper bottom plate and the lower bottom plate by adjusting the screw and the nut, so as to isolate the caisson shell from the fuel tank. The trapezoidal sealing cone cooperates with the sealing cone groove to further ensure the isolation and sealing effect. The structure is simple, conducive to processing and production, in line with economic benefits, and has high versatility.

[0021] 2. The inertable cryogenic caisson device and its piping system are provided with caisson components, caisson external piping system and caisson inlet piping system. Before inspecting and maintaining the pump body, nitrogen is used to blow out LPG / LNG in the caisson shell through the air inlet cavity, and is released to the safe area of ​​the breathable mast through the caisson external piping system, so as to avoid dead corners inside the caisson shell during the entire fuel tank blowing operation, resulting in LPG / LNG residue. By blowing out the caisson components separately and then opening the caisson shell to carry out pump body maintenance operations, potential safety hazards can be eliminated more thoroughly.

[0022] 3. The inertable low-temperature caisson device and its piping system are provided with a caisson assembly, a caisson external piping system and a caisson inlet piping system. After the pump body is installed in the caisson shell, nitrogen can be used to replace the natural air in the caisson shell and inertate the caisson area through the air intake cavity before the fuel tank is filled with LPG / LNG and the pump body is operated, so as to prevent water vapor in the natural air from freezing after encountering low-temperature LPG / LNG and affecting the operation of the pump body.

[0023] 4. The inertable low-temperature caisson device and its piping system are provided with a caisson assembly, a caisson external piping system and a caisson inlet piping system. Before filling with LPG / LNG and operating the pump body, after nitrogen replacement of the caisson assembly, the low-temperature LPG / LNG evaporated gas can be used through the caisson external piping system to blow out nitrogen and pre-cool the pump body, pump shaft and pump impeller, and gradually cool the upper and lower body temperatures to within an acceptable range, thereby avoiding excessive temperature differences between the upper and lower positions, which may cause shrinkage and deformation of the upper and lower components and inconsistent stresses when the low-temperature medium flows through the pump body during operation, thus causing damage to the pump.

[0024] 5. The inertable low-temperature caisson device and its piping system, by setting up the caisson assembly, the caisson external piping system and the caisson inlet piping system, closing the upper bottom plate and the lower bottom plate and valve one, opening valve seven, allowing nitrogen to enter the caisson shell, adjusting the pressure through the pressure regulator, can test the caisson assembly and detect whether there is leakage, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of an inertable cryogenic caisson device and its piping system proposed by the present invention;

[0026] Figure 2 A cross-sectional view of the lower sealing plate structure of an inertable low-temperature caisson device and its piping system proposed by the present invention;

[0027] Figure 3 A cross-sectional view of the lower bottom plate structure of an inertable cryogenic caisson device and its piping system proposed by the present invention;

[0028] Figure 4 A schematic diagram of an inertable cryogenic caisson device and its piping system, a caisson external piping system and a caisson inlet piping system;

[0029] Figure 5 A top view of the structure of a caisson assembly of an inertable low-temperature caisson device and its piping system proposed by the present invention;

[0030] Figure 6 A schematic diagram of the opening of the lower bottom plate and the upper bottom plate of an inertable low-temperature caisson device and its piping system proposed by the present invention;

[0031] Figure 7 This is a schematic diagram of lifting out the pump body of an inertable low-temperature caisson device and its piping system proposed by the present invention.

[0032] In the figure: 1. caisson assembly; 11. caisson shell; 12. upper bottom plate; 121. sealing cone groove; 13. lower sealing plate; 131. air inlet cavity; 132. sealing ring; 14. lower bottom plate; 141. trapezoidal sealing cone; 15. screw; 151. nut; 16. upper sealing plate; 17. upper member; 18. pump outlet flange; 19. pump body; 191. pump shaft; 192. pump impeller; 2. fuel tank; 3. caisson external piping system; 31. valve one; 32. valve two; 321. ventilation mast; 33. valve three; 34. valve four; 341. return air pipe; 35. one-way valve one; 36. valve five; 361. air inlet pipe; 37. valve six; 38. connecting pipe; 4. caisson inlet piping system; 41. valve seven; 42. one-way valve two; 43. pressure regulator; 44. nitrogen bottle. DETAILED DESCRIPTION

[0033] 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 described embodiments 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.

[0034] See also Figure 1-7 , an inertable cryogenic caisson device and its piping system, comprising:

[0035] The caisson assembly 1 is used to protect the pump body 19 inside the caisson assembly 1. The caisson assembly 1 includes a caisson shell 11 arranged inside the fuel tank 2. An upper bottom plate 12 is arranged at one end of the caisson shell 11. A lower sealing plate 13 is arranged at the other end of the caisson shell 11. A lower bottom plate 14 is arranged at the bottom of the upper bottom plate 12. An upper sealing plate 16 for mounting an upper member 17 is arranged at the top of the lower sealing plate 13. A top end of the lower bottom plate 14 sequentially penetrates the upper bottom plate 12, the lower sealing plate 13 and the upper sealing plate 16 and extends to the top of the upper sealing plate 16. The screw 15 is used to adjust the distance between the upper base plate 12 and the lower base plate 14. To ensure that the installation and closing of the upper base plate 12 and the lower base plate 14 can be performed, the total height of the caisson assembly 1 is designed not to exceed 20m. The opening and closing of the upper base plate 12 and the lower base plate 14 can be controlled by adjusting the screw 15 and the nut 151 to isolate the caisson shell 11 from the fuel tank 2. The trapezoidal sealing cone 141 cooperates with the sealing cone groove 121 to further ensure the isolation and sealing effect. The structure is simple, conducive to processing and production, in line with economic benefits, and has high versatility.

[0036] A trapezoidal sealing cone 141 is provided at the top of the lower base plate 14, and the top of the trapezoidal sealing cone 141 extends to the interior of the upper base plate 12, so as to block the connection between the caisson shell 11 and the pump body 19 and the fuel tank 2. When the lower base plate 14 drives the trapezoidal sealing cone 141 to separate from the interior of the upper base plate 12, the connection between the caisson shell 11 and the pump body 19 and the fuel tank 2 is realized. An air inlet cavity 131 connected with the interior of the caisson shell 11 is provided inside the lower sealing plate 13, so as to connect the gas inside the inerting caisson shell 11 and the pump body 19.

[0037] As a specific technical solution of this embodiment, a sealing cone groove 121 matching a trapezoidal sealing cone 141 is provided at the bottom of the lower base plate 14, and the top of the trapezoidal sealing cone 141 extends to the interior of the sealing cone groove 121. The sides of the trapezoidal sealing cone 141 and the sealing cone groove 121 are consistent with the horizon angle, and the angle range is between 55° and 65°.

[0038] In the present embodiment, the setting of the sealing cone groove 121 is coordinated with the trapezoidal sealing cone 141 and the side of the sealing cone groove 121 are designed to be consistent with the angle of the horizon, so that the trapezoidal sealing cone 141 and the sealing cone groove 121 fit well and maintain good sealing, effectively isolating the connection between the caisson shell 11 and the fuel tank 2, so that the caisson assembly 1 has the function of independent inerting. By blowing out the inerting caisson assembly 1 alone and then opening the caisson assembly 1 after blowing out the inerting to perform maintenance operations on the pump body 19, potential safety hazards can be eliminated more thoroughly and the use is safer.

[0039] As a specific technical solution of this embodiment, only one end of the surface of the screw rod 15 located at the upper sealing plate 16 has threads and is threadedly connected to a nut 151 , and the screw rod 15 can be lowered or lifted by rotating the nut 151 .

[0040] In this embodiment, the nut 151 is rotated clockwise to press downward against the top of the upper sealing plate 16, and the screw 15 moves upward. The screw 15 moves upward and drives the lower base plate 14 upward, so that the lower base plate 14 drives the trapezoidal sealing cone 141 to extend to the inside of the sealing cone groove 121, completing the sealing of the caisson shell 11. The nut 151 is rotated counterclockwise to lower the screw 15, so that the screw 15 drives the lower base plate 14 to disconnect from the upper base plate 12, and at the same time, the trapezoidal sealing cone 141 is disconnected from the inside of the sealing cone groove 121, so that the caisson shell 11 is connected to the fuel tank 2.

[0041] It should be noted that when there are several screw rods 15, during adjustment, it is necessary to make slight adjustments to several nuts 151 in sequence, so that the screw rods 15 can rise slowly in sequence, to prevent the screw rods 15 from getting stuck due to height deviation.

[0042] As a specific technical solution of this embodiment, the pump body 19 is arranged inside the caisson shell 11 , a pump shaft 191 is arranged inside the pump body 19 , and a pump impeller 192 is arranged on the surface of the pump shaft 191 .

[0043] In this embodiment, when the evaporated gas enters the caisson shell 11 through the fuel tank 2, the upper bottom plate 12 and the lower bottom plate 14 are opened, and the evaporated gas is counted into the evaporator through the evaporated gas source station and the air inlet pipe 361, so that the evaporated gas enters the internal channel of the pump impeller 192, moves upward, reaches the pump outlet flange 18, and returns to the evaporated gas source station by opening valve 1 31, valve 3 33, valve 4 34 and the return air pipe 341. The one-way valve 1 35 ensures that the intake air does not enter the pump outlet pipeline. According to this process, the low-temperature LPG / LNG evaporated gas can evenly pre-cool the pump body 19, the pump shaft 191 and the pump impeller 192, and finally achieves a temperature difference between the upper and lower positions within the allowable range.

[0044] When the fuel tank 2 uses LPG medium, the caisson assembly 1 is not cooled separately, but is cooled together with the fuel tank 2. Then, when the lowest temperature at the bottom of the pump body 19 reaches -43°C, the temperature of the pump outlet flange 18 is still at room temperature of 25°C. At this moment, the upper and lower temperature difference is 68°C, which exceeds the allowable amount. Then, a cooling cycle of the separate caisson assembly 1 can be carried out, and valve five 36 and valve six 37 are opened. The air source intake of the evaporating gas source station is adjusted, and air is introduced from the connecting pipe 38. The low-temperature LPG evaporating gas is used for cooling for 2 hours. The temperature of the pump outlet flange 18 drops to -15°C, and the lower bottom plate 14 becomes -40°C. Now the maximum temperature difference between the upper and lower positions becomes 25°C, which does not exceed 60°C. It is qualified after pre-cooling, and the fuel tank 2 can be filled and the pump body 19 can be operated subsequently.

[0045] The minimum temperature of LNG medium is -162℃. If the temperature of the pump outlet flange 18 is 25℃ at room temperature, and the lower bottom plate 14 has been cooled to -162℃ following the fuel tank 2, then the upper and lower temperature difference is 187℃, which exceeds the allowable amount. A separate caisson assembly 1 cooling cycle is used, and valve five 36 and valve six 37 are opened. The gas intake of the evaporating gas source station is adjusted, and air is introduced from the connecting pipe 38. The LNG evaporating gas is used for cooling for 7 hours. The temperature of the pump outlet flange 18 drops to -100℃, and the temperature at the lower bottom plate 14 becomes -162℃. Now the maximum temperature difference becomes 62℃, which does not exceed 150℃. It is qualified after pre-cooling, and the fuel tank 2 can be filled and the pump body 19 can be operated later.

[0046] As a specific technical solution of this embodiment, the diameter of the screw 15 is between 6mm and 15mm, the upper base plate 12 is provided with a through hole which is sleeved with the surface of the screw 15, and the gap between the through hole and the screw 15 is between 2mm and 6mm.

[0047] In this embodiment, the gap between the through hole and the screw 15 is between 2mm and 6mm to avoid the screw 15 being stuck in the through hole when the gap is too small, and the upper base plate 12 and the lower base plate 14 being too misaligned when the gap is too large, resulting in the misalignment of the trapezoidal sealing cone 141 and the sealing cone groove 121 and being unable to seal, thereby ensuring the stability of the device.

[0048] As a specific technical solution of this embodiment, the bottom of the lower sealing plate 13 is fixedly connected to the top of the fuel tank 2, and a sealing ring 132 is provided inside the lower sealing plate 13. The inside of the sealing ring 132 is movably connected to the surface of the screw 15 to achieve sealing between the lower sealing plate 13 and the fuel tank 2.

[0049] In this embodiment, the sealing ring 132 is used to ensure the sealing between the screw 15 and the upper sealing plate 16, that is, to ensure that the screw 15 and the fuel tank 2 are always in a relatively sealed state, thereby avoiding gas leakage through the connection between the screw 15 and the lower sealing plate 13, and also ensuring sealing when the screw 15 rotates.

[0050] As a specific technical solution of this embodiment, an upper component 17 is provided on the top of the upper sealing plate 16 by bolts, which is used to cooperate with the lifting equipment to lift the pump body 19. One end of the pump body 19 passes through the outside of the upper component 17 and is provided with a pump outlet flange 18.

[0051] In this embodiment, after the caisson assembly 1 is individually inerted, the potential safety hazard is completely eliminated, and then the caisson assembly 1 is opened for body maintenance. The bolts used to install the upper member 17 are removed, and the pump body 19 can be vertically lifted out through the upper member 17 using the shipyard's crane.

[0052] A piping system capable of inerting a cryogenic caisson device comprises a caisson external piping system 3 for inerting a fuel tank 2 and a caisson inlet piping system 4 for inerting a caisson outer shell 11 and a pump body 19, wherein the caisson external piping system 3 comprises an exhaust system, a return air system and an intake air system;

[0053] The exhaust system includes a valve 1 31, a valve 2 32 and a breathable mast 321 connected in sequence through pipelines, the valve 1 31 is connected to the pump outlet flange 18 through a flange, the return air system includes a valve 3 33, a valve 4 34 and a return air pipe 341 connected in sequence through pipelines, the valve 3 33 is connected to the valve 1 31 and the valve 2 32 through a pipeline, the intake system includes a one-way valve 1 35, a valve 5 36, an intake pipe 361 and a valve 6 37 connected in sequence through pipelines, the The one-way valve 1 35 is connected to the valve 3 33 and the valve 4 34 through the pipeline, the lower bottom plate 14 and the upper bottom plate 12 are closed, so that the caisson shell 11 is isolated from the fuel tank 2, and the nitrogen blowing pressure is adjusted by the pressure regulator 43, and the valve 7 41, the valve 1 31 and the valve 2 32 are opened, and the nitrogen is used to blow the LPG / LNG through the air inlet cavity 131, and the LPG / LNG and the evaporated gas flow from the caisson shell 11 to the suction port at the bottom of the pump body 19, and then along the internal delivery pipeline of the pump shaft 191 to reach The pump outlet flange 18 is located at the pump outlet flange 18, and is released to the safe area of ​​the breathable mast 321 through valve 1 31 and valve 2 32, so as to avoid dead corners inside the caisson shell 11 during the blowing operation of the entire fuel tank 2, making the blowing operation more thorough. After the pump body 19 is installed in the caisson shell 11, the natural air in the caisson shell 11 can be replaced by nitrogen through the air inlet cavity 131 before the fuel tank 2 is filled with LPG / LNG and the pump body 19 is operated, so as to inertate the caisson area and avoid water vapor in the natural air from encountering the low-temperature LPG / LNG. LNG will freeze and affect the operation of the pump body 19. Before filling with LPG / LNG and operating the pump body 19, the caisson assembly 1 should be replaced with nitrogen. The low-temperature LPG / LNG evaporated gas can be used through the caisson external piping system 3 to blow out the nitrogen and pre-cool the pump body 19, pump shaft 191 and pump impeller 192, and gradually cool them until the temperature difference between the upper and lower bodies is within the tolerable temperature difference range, so as to avoid excessive temperature difference between the upper and lower positions. When the pump body 19 is running, the low-temperature medium flows through, causing the upper and lower components to shrink and deform, and the stress is inconsistent, causing damage to the pump.

[0054] As a specific technical solution of this embodiment, the valve six 37 is connected to the interior of the fuel tank 2 through a connecting pipe 38, and the caisson inlet pipeline system 4 includes a valve seven 41, a one-way valve two 42, a pressure regulator 43 and a nitrogen bottle 44 connected in sequence through pipelines. The valve seven 41 is connected to the air inlet cavity 131 through a pipeline. When the nitrogen bottle 44 transports nitrogen into the caisson shell 11 and the inside of the pump body 19 through the air inlet cavity 131, the pressure regulator 43 regulates the pressure of the flowing nitrogen.

[0055] In this embodiment, valve seven 41, one-way valve two 42 and pressure regulator 43 are used to transport and control nitrogen, and the inside of the caisson shell 11 is blown out through the air inlet chamber 131. The pressure regulator 43 is used to reduce the pressure of the nitrogen to avoid excessive pressure and excessive flow rate that may damage equipment and waste gas resources. It is in line with economic benefits and is more energy-saving and environmentally friendly.

[0056] When in use, this solution only takes LPG and LNG as examples. The medium can also be ethane, butane, ethylene and other media that need to be stored in low-temperature liquefied form. The caisson assembly 1 can be used not only in fuel tanks but also in transport storage tanks. In this solution, the height, diameter, upper sealing plate 16 and air inlet cavity 131 type and size, upper bottom plate 12 and lower bottom plate 14 sealing type and size, etc. of the caisson assembly 1 can be configured differently according to needs to meet the needs of various practical applications of ships. The initial state of the upper bottom plate 12 and the lower bottom plate 14 is a closed state. Turn the nut 1 clockwise. 51 moves downward against the top of the upper sealing plate 16, and the screw 15 moves upward. The screw 15 moves upward and drives the lower bottom plate 14 upward, so that the lower bottom plate 14 drives the trapezoidal sealing cone 141 to extend to the inside of the sealing cone groove 121, completing the sealing of the caisson shell 11. The nut 151 is rotated counterclockwise to lower the screw 15, so that the screw 15 drives the lower bottom plate 14 to break away from the connection with the upper bottom plate 12, and at the same time, the trapezoidal sealing cone 141 breaks away from the inside of the sealing cone groove 121, so that the caisson shell 11 is connected with the fuel tank 2. The device has the following usage modes:

[0057] To blow down the inerting caisson assembly 1 separately, refer to Figure 1-3 Before inspecting and maintaining the pump body 19, first close the upper bottom plate 12 and the lower bottom plate 14, adjust the nitrogen blowing pressure through the pressure regulator 43, open valve valve seven 41, valve one 31 and valve two 32, use nitrogen to blow LPG / LNG through the air inlet chamber 131, LPG / LNG and evaporated gas flow from the caisson shell 11 down to the suction port at the bottom of the pump body 19, and then along the internal delivery pipeline of the pump shaft 191 to the pump outlet flange 18, and are released to the safe area of ​​the vent mast 321 through valve valve one 31 and valve two 32 to avoid the entire During the blowing operation of the fuel tank 2, there is a dead corner inside the caisson, resulting in LPG / LNG residue. The nitrogen pressure can be adjusted to 6 bar for blowing operation, and the hydrocarbon concentration can be detected by a portable detector at the pump outlet flange 18. When the concentration is detected to be lower than 25% LEL, it is qualified and the inerting is completed. By blowing the inerting caisson function alone, the potential safety hazard can be eliminated more thoroughly. After blowing, the caisson can be opened to take out the pump for maintenance. The bolts used to install the upper structure 17 can be removed, and the pump body 19 can be vertically lifted out through the upper structure 17 by the crane of the ship repair yard.

[0058] The natural air in the caisson assembly 1 is replaced by nitrogen. After the pump body 19 is installed in the caisson shell 11, the caisson shell 11 is filled with natural air. The upper bottom plate 12 and the lower bottom plate 14 are closed and in a sealed state. Before the fuel tank 2 is filled with LPG / LNG and the pump body 19 is operated, the valve can be opened through the air inlet cavity 131 to adjust the pressure of the pressure regulator 43, and the natural air in the caisson is replaced by nitrogen. The air is blown out to the safe area of ​​the breathable mast 321 by opening valve 1 31 and valve 2 32. By inerting the caisson shell 11 area with nitrogen, water vapor in the natural air is prevented from encountering the low-temperature LPG / LNG. G / LNG will freeze after freezing, which will affect the operation of the pump body 19. The nitrogen needs to be dried. When the fuel medium is LPG, the dew point is lower than -8°C. When the fuel medium is LNG, the dew point is lower than -60°C. After a period of nitrogen replacement, the O2 content in the caisson shell 11 is measured by a portable instrument and is lower than 2%. The replacement is completed. The process is similar to the previous step of blowing off the LPG / LNG evaporated gas for inerting, but the timing of use is different. One is before the maintenance of the pump body 19, and the other is before the pump body 19 is installed and filled with LPG / LNG. When operating in this mode, valve three 33 remains closed;

[0059] Precool the pump body 19, see Figure 4 The external piping system 3 of the caisson is composed of valve 1 31, valve 2 32, air mast 321, valve 3 33, valve 4 34, return pipe 341, check valve 1 35, valve 5 36, air intake pipe 361, valve 6 37 and connecting pipe 38. Valve 1 31 is connected to the pump outlet flange 18. The air intake enters the interior of the fuel tank 2 through the air intake pipe 361, valve 5 36, valve 6 37 and connecting pipe 38. Before filling LPG / LNG and pump body 19, after nitrogen replacement of the caisson assembly 1, the low-temperature LPG / LNG evaporated gas can be used through the external piping system 3 of the caisson to blow away the nitrogen and pre-cool the pump body 19, the pump shaft 191 and the pump impeller 192, and gradually cool the temperature difference between the upper body and the lower body to within the tolerable temperature difference range. To avoid too large a temperature difference between the upper and lower positions, which may cause cold shrinkage deformation and inconsistent stress and cause damage to the pump, the low-temperature LPG / LNG evaporated gas comes from the external gas source station. By opening valve five 36 and valve six 37, it is connected to the inside of the fuel tank 2 from the connecting pipe 38, and the upper bottom plate 12 and the lower bottom plate 14 are opened to allow the evaporated gas to enter the internal channel of the pump impeller 192, move upward, reach the pump outlet flange 18, and return to the evaporated gas source station by opening valve one 31, valve three 33, valve four 34 and return pipe 341. The one-way valve one 35 ensures that the intake air will not enter the pump outlet pipeline. According to this process, the low-temperature LPG / LNG evaporated gas can evenly pre-cool the pump body 19, the pump shaft 191 and the pump impeller 192, and finally achieve a temperature difference between the upper and lower positions within the allowable range;

[0060] The pressure test is similar to the nitrogen replacement process, except that valve 131, the upper bottom plate 12 and the lower bottom plate 14 are closed, the pump outlet valve 131 is further closed, and valve 7 41 is opened to allow nitrogen to enter the caisson shell 11. The pressure regulator 43V6 adjusts the pressure to the test pressure, such as 6 bar, and maintains the pressure for 15 minutes. If there is no pressure drop, the sealing and strength test of the caisson shell 11 are verified to be qualified.

[0061] In summary, the inertable low-temperature caisson device and its piping system, by setting up the caisson assembly 1, can control the opening and closing of the upper base plate 12 and the lower base plate 14 by adjusting the screw 15 and the nut 151, so as to isolate the caisson shell 11 from the fuel tank 2. The trapezoidal sealing cone 141 cooperates with the sealing cone groove 121 to further ensure the isolation and sealing effect. The structure is simple, conducive to processing and production, in line with economic benefits, and has high versatility.

[0062] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0063] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An inertable cryogenic caisson device, characterized in that: include: A caisson assembly (1) is used to protect a pump body (19) inside the caisson assembly (1), the caisson assembly (1) comprising a caisson shell (11) arranged inside a fuel tank (2), an upper bottom plate (12) being arranged at one end of the caisson shell (11), a lower sealing plate (13) being arranged at the other end of the caisson shell (11), a lower bottom plate (14) being arranged at the bottom of the upper bottom plate (12), an upper sealing plate (16) for mounting an upper component (17) being arranged at the top of the lower sealing plate (13), a screw rod (15) being arranged at the top of the lower bottom plate (14), the top end of which sequentially penetrates the upper bottom plate (12), the lower sealing plate (13) and the upper sealing plate (16) and extends to the top of the upper sealing plate (16), the screw rod (15) being used to adjust the distance between the upper bottom plate (12) and the lower bottom plate (14); A trapezoidal sealing cone (141) is provided at the top of the lower bottom plate (14), and the top of the trapezoidal sealing cone (141) extends to the interior of the upper bottom plate (12), so as to block the connection between the caisson shell (11) and the pump body (19) and the fuel tank (2). When the lower bottom plate (14) drives the trapezoidal sealing cone (141) to separate from the interior of the upper bottom plate (12), the connection between the caisson shell (11) and the pump body (19) and the fuel tank (2) is achieved. An air inlet cavity (131) connected to the interior of the caisson shell (11) is provided inside the lower sealing plate (13), so as to be connected to the gas inside the inerting caisson shell (11) and the pump body (19).

2. The inertable cryogenic caisson device according to claim 1, characterized in that: The bottom of the lower base plate (14) is provided with a sealing cone groove (121) matched with the trapezoidal sealing cone (141), the top of the trapezoidal sealing cone (141) extends to the inside of the sealing cone groove (121), and the sides of the trapezoidal sealing cone (141) and the sealing cone groove (121) are consistent with the horizon angle, and the angle range is between 55° and 65°.

3. The inertable cryogenic caisson device according to claim 1, characterized in that: The surface of the screw rod (15) is threaded only at one end located at the upper sealing plate (16) and is threadedly connected to a nut (151). The screw rod (15) can be lowered or raised by rotating the nut (151).

4. The inertable cryogenic caisson device according to claim 1, characterized in that: The pump body (19) is arranged inside the caisson shell (11), a pump shaft (191) is arranged inside the pump body (19), and a pump impeller (192) is arranged on the surface of the pump shaft (191).

5. The inertable cryogenic caisson device according to claim 1, characterized in that: The diameter of the screw (15) is between 6 mm and 15 mm. A through hole is provided inside the upper base plate (12) and is sleeved with the surface of the screw (15). The gap between the through hole and the screw (15) is between 2 mm and 6 mm.

6. The inertable cryogenic caisson device according to claim 1, characterized in that: The bottom of the lower sealing plate (13) is fixedly connected to the top of the fuel tank (2), and a sealing ring (132) is provided inside the lower sealing plate (13). The inside of the sealing ring (132) is movably sleeved with the surface of the screw (15) to achieve sealing between the lower sealing plate (13) and the fuel tank (2).

7. The inertable cryogenic caisson device according to claim 1, characterized in that The top of the upper sealing plate (16) is provided with an upper member (17) by means of bolts, and is used to cooperate with a lifting device to lift the pump body (19); one end of the pump body (19) penetrates the outside of the upper member (17) and is provided with a pump outlet flange (18).

8. A piping system for an inertable cryogenic caisson device according to any one of claims 1 to 7, comprising a caisson external piping system (3) for inerting a fuel tank (2) and a caisson inlet piping system (4) for inerting a caisson outer shell (11) and a pump body (19), characterized in that : The caisson external piping system (3) includes an exhaust system, a return air system and an intake air system; The exhaust system comprises a valve 1 (31), a valve 2 (32) and a ventilation mast (321) which are sequentially connected through a pipeline, and the valve 1 (31) is connected to a pump outlet flange (18) through a flange; The air return system comprises a valve three (33), a valve four (34) and an air return pipe (341) which are sequentially connected through pipelines, and the valve three (33) is connected to the valve one (31) and the valve two (32) through the pipeline; The air intake system comprises a one-way valve (35), a valve (36), an air intake pipe (361) and a valve (37) which are sequentially connected via pipelines. The one-way valve (35) is connected to valves (33) and (4) via pipelines.

9. The piping system of the cryogenic caisson device capable of being inerted according to claim 8, characterized in that The valve six (37) is connected to the interior of the fuel tank (2) through a connecting pipe (38), and the caisson inlet pipeline system (4) includes a valve seven (41), a check valve two (42), a pressure regulator (43) and a nitrogen bottle (44) which are sequentially connected through pipelines.

10. The piping system for inerting a cryogenic caisson device according to claim 9, characterized in that The valve seven (41) is connected to the air inlet chamber (131) through a pipeline. When the nitrogen bottle (44) delivers nitrogen through the air inlet chamber (131) into the caisson shell (11) and the pump body (19), the pressure regulator (43) regulates the pressure of the flowing nitrogen.

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