1. An inertable cryogenic caisson device and piping system therefor, comprising:

the caisson component (1) is used for protecting a pump body (19) inside the caisson component, the caisson component (1) comprises a caisson shell (11) arranged inside a fuel tank (2), an upper base 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 base plate (14) is arranged at the bottom of the upper base plate (12), an upper sealing plate (16) used for mounting an upper component (17) is arranged at the top of the lower sealing plate (13), a screw rod (15) is arranged at the top of the lower base plate (14), the top end of the screw rod penetrates through the upper base plate (12), the lower sealing plate (13) and the upper sealing plate (16) in sequence and extends to the top of the upper sealing plate (16), and the screw rod (15) is used for adjusting the distance between the upper base plate (12) and the lower base plate (14);

the top of lower plate (14) is provided with trapezoidal sealed awl (141), the inside of the top extension of trapezoidal sealed awl (141) to bottom plate (12), realizes blocking caisson shell (11) and pump body (19) and fuel jar (2) intercommunication, works as when bottom plate (14) drive trapezoidal sealed awl (141) and break away from the inside of upper plate (12), realize caisson shell (11) and pump body (19) and fuel jar (2)'s intercommunication, air inlet chamber (131) that are linked together with caisson shell (11) inside are seted up to the inside of lower shrouding (13) for connect into the inside gas of inerting caisson shell (11) and pump body (19).

2. An inertable cryogenic caisson device and piping system therefor according to claim 1, wherein: the bottom of lower plate (14) is seted up and is sealed awl groove (121) that matches with trapezoidal sealed awl (141), the inside that sealed awl groove (121) was extended to the top of trapezoidal sealed awl (141), the avris of trapezoidal sealed awl (141) and sealed awl groove (121) all is unanimous with the horizon angle, and the angle range is between 55 to 65.

3. An inertable cryogenic caisson device and piping system therefor according to claim 1, wherein: the surface of the screw rod (15) is only located at one end of the upper sealing plate (16) and is provided with a thread and a nut (151), and the nut (151) is rotated to lower or lift the screw rod (15).

4. An inertable cryogenic caisson device and piping system therefor according to claim 1, wherein: the pump body (19) is arranged inside the caisson casing (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. An inertable cryogenic caisson device and piping system therefor according to claim 1, wherein: the diameter of the screw rod (15) is 6-15 mm, a through hole is formed in the upper bottom plate (12) and is sleeved with the surface of the screw rod (15), and the gap between the through hole and the screw rod (15) is 2-6 mm.

6. An inertable cryogenic caisson device and piping system therefor according to claim 1, wherein: the bottom of lower shrouding (13) and the top fixed connection of fuel jar (2), the inside of lower shrouding (13) is provided with sealing ring (132), the inside of sealing ring (132) cup joints with the surface activity of screw rod (15), is used for realizing the sealed between lower shrouding (13) and fuel jar (2).

7. An inertable cryogenic caisson device and piping system therefor according to claim 1, wherein the top of the upper sealing plate (16) is provided with an upper member (17) by bolts for lifting the pump body (19) in cooperation with a lifting device, and 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. Piping system for an inertable cryogenic caisson arrangement according to claims 1 to 7, comprising an external caisson piping system (3) for inerting the fuel tank (2) and an inlet caisson piping system (4) for inerting the caisson casing (11) and the pump body (19), characterised in that the external caisson piping system (3) comprises an exhaust system, a return air system and an intake system;

the exhaust system comprises a first valve (31), a second valve (32) and a ventilating mast (321) which are sequentially connected through a pipeline, wherein the first valve (31) is connected with a pump outlet flange (18) through a flange;

the air return system comprises a valve III (33), a valve IV (34) and an air return pipe (341) which are sequentially connected through a pipeline, wherein the valve III (33) is communicated with a valve I (31) and a valve II (32) through pipelines;

the air inlet system comprises a first check valve (35), a fifth valve (36), an air inlet pipe (361) and a sixth valve (37) which are sequentially connected through pipelines, wherein the first check valve (35) is communicated with the third valve (33) and the fourth valve (34) through pipelines.

9. An inertable cryogenic caisson device and piping system therefor according to claim 1, wherein the valve six (37) is connected to the inside of the fuel tank (2) by a connecting pipe (38), and the caisson inlet piping system (4) comprises a valve seven (41), a check valve two (42), a pressure regulator (43), and a nitrogen gas cylinder (44) connected in sequence by piping.

10. An inertable cryogenic caisson device and piping system therefor according to claim 9, wherein said valve seven (41) is connected by piping to the gas inlet chamber (131), and said pressure regulator (43) regulates the flow of nitrogen as said nitrogen cylinder (44) feeds nitrogen through the gas inlet chamber (131) into the caisson casing (11) and into the interior of the pump body (19).

Background

LPG (liquefied petroleum gas)/LNG (liquefied natural gas) powered vessels, also known as LNG powered vessels/LNG powered vessels, on which fuel is transported from a fuel tank to a host by a cryogenic pump, the cryogenic pump being mounted in the tank, a caisson is mounted inside the fuel tank in order to protect the cryogenic pump, the cryogenic pump is mounted in the caisson, and a suction port is located at the bottom, but the current caisson device has the following disadvantages when in use:

conventional caisson bottom is for opening, with fuel jar UNICOM, just can maintain and caisson inner space be the dead angle after need accomplishing with the jar body inertization simultaneously, has LPG/LNG vaporization thing remaining easily during the inertization, causes the burning explosion harm and has the accident hidden danger, can't satisfy the user demand yet.

Disclosure of Invention

In order to achieve the purpose, the invention provides the following technical scheme: an inertable cryogenic caisson device and piping system therefor, comprising:

the caisson component is used for protecting a pump body in the caisson component, the caisson component comprises a caisson shell arranged in a fuel tank, an upper base 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 base plate is arranged at the bottom of the upper base plate, an upper sealing plate used 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 base plate, the top end of the screw rod penetrates through the upper base plate, the lower sealing plate and the upper sealing plate in sequence and extends to the top of the upper sealing plate, and the screw rod is used for adjusting the distance between the upper base plate and the lower base plate;

the top of lower plate is provided with trapezoidal sealed awl, the inside of trapezoidal sealed awl extends to the upper plate realizes blocking the intercommunication of caisson shell and pump body and fuel jar works as when the lower plate drives trapezoidal sealed awl and breaks away from the inside of upper plate, realizes the intercommunication of caisson shell and pump body and fuel jar, the air inlet chamber that is linked together with caisson shell inside is seted up to the inside of lower shrouding for insert the gas of inertization caisson shell and the inside of the pump body.

According to a preferable technical scheme of the invention, the bottom of the lower bottom plate is provided with a sealing cone groove matched with the trapezoidal sealing cone, the top of the trapezoidal sealing cone extends into the sealing cone groove, the edges of the trapezoidal sealing cone and the sealing cone groove are consistent with the ground plane in angle, and the angle range is 55-65 degrees.

As a preferable technical scheme of the invention, the screw is lowered or lifted by rotating the nut, and the screw is threaded at one end of the surface of the screw, which is only positioned at the upper sealing plate, and the nut is connected with the screw in a threaded manner.

As a preferred technical solution of the present invention, the pump body is disposed inside the caisson casing, the pump shaft is disposed inside the pump body, and the pump impeller is disposed on a surface of the pump shaft.

As a preferable technical scheme of the invention, the diameter of the screw is 6-15 mm, a through hole is formed in the upper bottom plate, the inner part of the through hole is sleeved with the surface of the screw, and the gap between the through hole and the screw is 2-6 mm.

As a preferable 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 disposed inside the lower sealing plate, and the inside of the sealing ring is movably sleeved on the surface of the screw rod for sealing the lower sealing plate and the fuel tank.

As a preferred technical scheme of the present invention, the top of the upper sealing plate is provided with an upper member through a bolt for cooperating with a hoisting device to hoist the pump body, and one end of the pump body penetrates through the outer portion of the upper member and is provided with a pump outlet flange.

A pipeline system of a inertable cryogenic caisson device comprises a caisson external pipeline system used for inerting a fuel tank and a caisson inlet pipeline system used for inerting a caisson shell and a pump body, wherein the caisson external pipeline system comprises an exhaust system, an air return system and an air intake system;

the exhaust system comprises a first valve, a second valve and a breathable mast which are sequentially connected through a pipeline, wherein the first valve is connected with an outlet flange of the pump through a flange;

the air return system comprises a valve III, a valve IV and an air return pipe which are sequentially connected through a pipeline, and the valve III is communicated with the valve I and the valve II through pipelines;

the air inlet system comprises a first check valve, a fifth valve, an air inlet pipe and a sixth valve which are sequentially connected through pipelines, and the first check valve is communicated with the third valve and the fourth valve through pipelines.

As a preferable technical scheme of the invention, the valve VI is communicated with the interior of the fuel tank through a connecting pipe, and the caisson inlet pipeline system comprises a valve VII, a one-way valve II, a pressure regulator and a nitrogen cylinder which are sequentially connected through pipelines.

As a preferred technical scheme of the invention, the valve seventh is communicated with the air inlet cavity through a pipeline, and when the nitrogen cylinder conveys nitrogen into the caisson shell and the interior of the pump body through the air inlet cavity, the pressure regulator regulates the pressure of the flowing nitrogen.

Compared with the prior art, the inerting low-temperature caisson device and the pipeline system thereof have the following beneficial effects:

1. this but low temperature caisson device of inertization and pipe-line system thereof through setting up the caisson subassembly, can control opening and closing of upper plate and lower plate promptly through adjusting screw and nut, keeps apart caisson shell and fuel jar, and trapezoidal sealed awl cooperation seals the taper groove, has further guaranteed to keep apart sealed effect, and simple structure does benefit to processing production, accords with economic benefits, has higher commonality.

2. This can inertization low temperature caisson device and pipe-line system thereof, through setting up the caisson subassembly, outside pipe-line system of caisson and caisson import pipe-line system, before overhauing and maintaining the pump body, use nitrogen gas to blow off caisson shell the inside LPG/LNG through the air inlet chamber, and release to ventilative mast safe region through outside pipe-line system of caisson, there is the dead angle at caisson shell inside when avoiding whole fuel jar to blow off the operation, lead to LPG/LNG to remain, blow off the caisson subassembly alone, open the caisson shell again after blowing off and carry out the pump body and maintain the operation, can more thoroughly eliminate accident potential.

3. According to the inertable low-temperature caisson device and the pipeline system thereof, by arranging the caisson component, the caisson external pipeline system and the caisson inlet pipeline system, after the pump body is installed in the caisson shell, before LPG/LNG is filled into the fuel tank and the pump body operates, natural air and an inerting caisson area in the caisson shell can be replaced by nitrogen through the air inlet cavity, and the phenomenon that water vapor in the natural air freezes after encountering low-temperature LPG/LNG and influences the operation of the pump body is avoided.

4. This can inertize low temperature caisson device and pipe-line system thereof, through setting up caisson subassembly, caisson outside pipe-line system and caisson import pipe-line system, before filling LPG/LNG and pump body operation, carry out nitrogen gas replacement to the caisson subassembly after, accessible caisson outside pipe-line system uses low temperature LPG/LNG evaporation gas to blow off nitrogen gas and precool the pump body, pump shaft and pump impeller, gradually cool off to upper part of the body and lower part of the body difference in temperature can bear the difference in temperature scope, avoid upper and lower position difference in temperature too big, the low temperature medium stream process causes upper and lower part shrink deformation and stress nonconformity arouses the pump to be hurt when the pump body moves.

5. This can inertization low temperature caisson device and pipe-line system thereof through setting up caisson subassembly, the outside pipe-line system of caisson and caisson import pipe-line system, closes upper plate and lower plate and valve one, opens valve seven, lets nitrogen gas get into the caisson shell, adjusts good pressure through pressure regulator, can carry out the pressure testing and detect the caisson subassembly and whether have the leakage, has wide application prospect.

Drawings

FIG. 1 is a schematic structural view of an inertable cryogenic caisson device and piping system therefor according to the present invention;

FIG. 2 is a cross-sectional view of the lower closure plate structure of the inertable cryogenic caisson device and piping system thereof according to the present invention;

FIG. 3 is a cross-sectional view of a lower plate structure of an inertable low temperature caisson apparatus and piping system thereof according to the present invention;

FIG. 4 is a schematic view of the external caisson piping system and the caisson inlet piping system of a inertable cryogenic caisson device and piping system thereof according to the present invention;

FIG. 5 is a top view of a caisson component structure of an inertable cryogenic caisson device and piping system therefor, according to the invention;

FIG. 6 is a schematic view of the opening of the lower plate and the upper plate of the inertable low temperature caisson device and the piping system thereof according to the present invention;

fig. 7 is a schematic diagram of the pump body of the inerting cryogenic caisson device and the piping system thereof according to the present invention.

In the figure: 1. a caisson component; 11. a caisson shell; 12. an upper base plate; 121. sealing the conical groove; 13. a lower sealing plate; 131. an air inlet cavity; 132. a seal ring; 14. a lower base plate; 141. a trapezoidal sealing cone; 15. a screw; 151. a nut; 16. an upper sealing plate; 17. an upper member; 18. an outlet flange of the pump; 19. a pump body; 191. a pump shaft; 192. a pump impeller; 2. a fuel tank; 3. a caisson external piping system; 31. a first valve; 32. a second valve; 321. a breathable mast; 33. a third valve; 34. a fourth valve; 341. an air return pipe; 35. a one-way valve I; 36. a fifth valve; 361. an air inlet pipe; 37. a sixth valve; 38. a connecting pipe; 4. a caisson inlet piping system; 41. a valve seventh; 42. a second one-way valve; 43. a pressure regulator; 44. a nitrogen cylinder.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-7, an inertable cryogenic caisson apparatus and piping system therefor, comprising:

the caisson component 1 is used for protecting a pump body 19 in the caisson component 1, the caisson component 1 comprises a caisson shell 11 arranged in a fuel tank 2, an upper base 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 base plate 14 is arranged at the bottom of the upper base plate 12, an upper sealing plate 16 used for installing an upper component 17 is arranged at the top of the lower sealing plate 13, a screw rod 15 is arranged at the top of the lower base plate 14, the top end of the screw rod penetrates through the upper base plate 12, the lower sealing plate 13 and the upper sealing plate 16 in sequence and extends to the top of the upper sealing plate 16, the screw rod 15 is used for adjusting the distance between the upper base plate 12 and the lower base plate 14, the installation and the closing of the upper base plate 12 and the lower base plate 14 can be carried out, the total height of the caisson component 1 is not more than 20m, and the opening and closing of the upper base plate 12 and the lower base plate 14 can be controlled by adjusting the screw rod 15 and a nut 151, isolate caisson shell 11 and fuel jar 2, trapezoidal sealed awl 141 cooperation sealed awl groove 121 has further guaranteed to keep apart sealed effect, and simple structure does benefit to processing production, accords with economic benefits, has higher commonality.

The top of lower plate 14 is provided with trapezoidal sealed awl 141, the inside of trapezoidal sealed awl 141 extends to bottom plate 12 realizes blocking caisson shell 11 and pump body 19 and fuel jar 2's intercommunication, works as lower plate 14 drives trapezoidal sealed awl 141 and breaks away from the inside of upper plate 12, realizes caisson shell 11 and pump body 19 and fuel jar 2's intercommunication, the intake chamber 131 that is linked together with caisson shell 11 is seted up to the inside of lower shrouding 13 for insert the inside gas of inerting caisson shell 11 and pump body 19.

As a specific technical solution of this embodiment, 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, the edges of the trapezoidal sealing cone 141 and the sealing cone groove 121 are both consistent with the horizontal line angle, and the angle range is 55 ° to 65 °.

In this embodiment, sealed awl groove 121 set up the design that trapezoidal sealed awl 141 of cooperation and sealed awl groove 121's avris all is unanimous with the horizon line angle, make trapezoidal sealed awl 141 with sealed awl groove 121 laminate and keep good leakproofness, effectively cut off caisson shell 11 and fuel jar 2's intercommunication, make caisson subassembly 1 have the function of inertization alone, through blowing inertization caisson subassembly 1 alone, open caisson subassembly 1 again after the inertization and carry out pump body 19 maintenance operation, accident potential can more thoroughly be eliminated, it is safer to use.

As a specific technical solution of this embodiment, only one end of the surface of the screw 15 located at the upper sealing plate 16 is threaded and is connected with a nut 151, and the screw 15 is lowered or lifted by rotating the nut 151.

In this embodiment, clockwise rotation nut 151 is at the top of 16 shroudings of conflicting down, screw rod 15 is the upward movement promptly, screw rod 15 drives lower plate 14 upward movement in the upward movement, thereby make lower plate 14 drive trapezoidal sealed awl 141 extend to the inside of sealed awl groove 121, accomplish the sealed to caisson shell 11, screw rod 15 is transferred to anticlockwise rotation nut 151, make screw rod 15 drive lower plate 14 break away from the connection to upper plate 12, trapezoidal sealed awl 141 breaks away from the inside of sealed awl groove 121 simultaneously, make caisson shell 11 be linked together with fuel jar 2.

When needing to be noticed, when having a plurality of screw rod 15, during the regulation, need carry out the micro-adjustment to a plurality of nut 151 in proper order, let screw rod 15 slowly rise in proper order, avoid screw rod 15 to block because of the discrepancy of height.

As a specific solution of this embodiment, the pump body 19 is disposed inside the caisson casing 11, the pump shaft 191 is disposed inside the pump body 19, and the pump impeller 192 is disposed on the surface of the pump shaft 191.

In this embodiment, when the boil-off gas enters the caisson shell 11 through the fuel tank 2, the upper base plate 12 and the lower base plate 14 are opened, the vaporizer is counted in the boil-off gas source station and the air inlet pipe 361, the boil-off gas enters the internal channel of the pump impeller 192 and moves upwards to reach the pump outlet flange 18, and returns to the boil-off gas source station by opening the first valve 31, the third valve 33, the fourth valve 34 and the air return pipe 341, and the first check valve 35 ensures that the inlet air does not enter the pump outlet pipeline, according to this flow, the low-temperature LPG/LNG boil-off gas can uniformly pre-cool the pump body 19, the pump shaft 191 and the pump impeller 192, and finally the temperature difference between the upper position and the lower position is within the allowable range.

When the fuel tank 2 uses LPG medium, the caisson component 1 is not cooled separately but is cooled together with the fuel tank 2, when the lowest temperature at the bottom of the pump body 19 reaches-43 ℃, the temperature of the pump outlet flange 18 is 25 ℃ at normal temperature, the temperature difference between the upper part and the lower part is 68 ℃, the temperature exceeds the allowable amount, the cooling circulation of the separate caisson component 1 can be carried out, the valve five 36 and the valve six 37 are opened, the air source air inflow of the evaporation gas source station is adjusted, air is fed from the connecting pipe 38, the temperature of the pump outlet flange 18 is reduced to-15 ℃, the temperature of the lower bottom plate 14 is changed to-40 ℃, the maximum temperature difference between the upper part and the lower part is changed to 25 ℃ at present, the temperature does not exceed 60 ℃, the temperature is qualified after precooling, and the filling operation to the.

The lowest temperature of the LNG medium is-162 ℃, if the temperature of the pump outlet flange 18 is 25 ℃ at normal temperature, and the position of the lower bottom plate 14 is cooled to-162 ℃ along with the fuel tank 2, the temperature difference between the upper part and the lower part is 187 ℃ and exceeds the allowable amount, a single caisson component 1 is adopted for cooling circulation, the five valve 36 and the six valve 37 are opened, the air source air inflow of the boil-off gas source station is adjusted, the air is fed from the connecting pipe 38, the LNG boil-off gas is used for cooling for 7 hours, the temperature of the pump outlet flange 18 is reduced to-100 ℃, the temperature of the lower bottom plate 14 is changed to-162 ℃, the maximum temperature difference is changed to 62 ℃ now and is not more than 150 ℃, the LNG medium is qualified after precooling, and then the LNG medium can be filled into the fuel tank 2 and the pump body 19 can be operated.

As a specific technical solution of this embodiment, the diameter of the screw 15 is between 6mm and 15mm, a through hole whose inside is sleeved with the surface of the screw 15 is formed inside the upper base plate 12, and a gap between the through hole and the screw 15 is between 2mm and 6 mm.

In the embodiment, the clearance between the through hole and the screw rod 15 is 2mm-6mm, so that the situation that the screw rod 15 is clamped with the through hole when the clearance is too small and the trapezoidal sealing cone 141 and the sealing cone groove 121 cannot be sealed due to too large dislocation of the upper base plate 12 and the lower base plate 14 when the clearance is too large is avoided, and the stability of the device is ensured.

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, a sealing ring 132 is disposed inside the lower sealing plate 13, and the inside of the sealing ring 132 is movably sleeved on the surface of the screw 15 for sealing the lower sealing plate 13 and the fuel tank 2.

In this embodiment, the sealing ring 132 is used to ensure the sealing between the screw 15 and the upper sealing plate 16, i.e. to ensure that the screw 15 and the fuel tank 2 are always in a relative sealing state, so as to prevent the gas from leaking through the joint between the screw 15 and the lower sealing plate 13, and to ensure the sealing when the screw 15 rotates.

As a specific technical solution of this embodiment, the top of the upper sealing plate 16 is provided with an upper member 17 through bolts for matching with a hoisting device to hoist the pump body 19, and one end of the pump body 19 penetrates through the outside of the upper member 17 and is provided with a pump outlet flange 18.

In this embodiment, after caisson component 1 is inerted alone, accident potential is eliminated thoroughly, and caisson component 1 is opened again to perform body maintenance work, and the bolt for installing upper member 17 is disassembled, and pump body 19 can be vertically lifted out through upper member 17 by using the crane in the shipyard.

A piping system of a inertable cryogenic caisson arrangement, comprising a caisson external piping system 3 for inerting a fuel tank 2 and a caisson inlet piping system 4 for inerting a caisson shell 11 and a pump body 19, said caisson external piping system 3 comprising an exhaust system, a return air system and an intake system;

the exhaust system comprises a first valve 31, a second valve 32 and a breathable mast 321 which are sequentially connected through a pipeline, the first valve 31 is connected with a pump outlet flange 18 through a flange, the air return system comprises a third valve 33, a fourth valve 34 and an air return pipe 341 which are sequentially connected through a pipeline, the third valve 33 is communicated with the first valve 31 and the second valve 32 through a pipeline, the air inlet system comprises a first check valve 35, a fifth valve 36, an air inlet pipe 361 and a sixth valve 37 which are sequentially connected through a pipeline, the first check valve 35 is communicated with the third valve 33 and the fourth valve 34 through a pipeline, the lower bottom plate 14 and the upper bottom plate 12 are closed, the caisson shell 11 is isolated from the fuel tank 2, the pressure regulator 43 is used for regulating the blowing pressure of nitrogen, the seventh valve 41, the first valve 31 and the second valve 32 are opened, and the nitrogen is used for blowing off/LPG through the air inlet cavity 131, LPG/LNG and boil-off gas go down from the caisson shell 11 to the suction inlet at the bottom end of the pump body 19, then reach the pump outlet flange 18 along the inner conveying pipeline of the pump shaft 191, and are released to the safe area of the ventilating mast 321 through the first valve 31 and the second valve 32, so as to avoid dead corners in the caisson shell 11 during the whole blowing operation of the fuel tank 2, so that the blowing operation is more thorough, after the pump body 19 is installed in the caisson shell 11, before the LPG filling/LNG and the pump body 19 of the fuel tank 2 are operated, natural air in the caisson shell 11 can be replaced by nitrogen through the air inlet cavity 131, the caisson area is inerted, water vapor in the natural air is prevented from freezing after encountering the LPG/LNG, so as to influence the operation of the pump body 19, before the LPG/LNG and the pump body 19 are operated, after the nitrogen replacement is performed on the caisson component 1, the low-temperature LPG/LNG pre-cooling boil-off gas can be used by the caisson external pipeline system 3 to blow off the nitrogen and the pump body 19, The pump shaft 191 and the pump impeller 192 are gradually cooled to a temperature difference between the upper body and the lower body within a tolerable temperature difference range, so that the pump is prevented from being damaged due to contraction deformation and stress inconsistency of the upper and lower parts caused by the fact that the temperature difference between the upper and lower positions is too large and the low-temperature medium flows through when the pump body 19 operates.

As a specific technical solution of this embodiment, the valve six 37 is communicated with the inside of the fuel tank 2 through a connecting pipe 38, the caisson inlet piping system 4 includes a valve seven 41, a check valve two 42, a pressure regulator 43 and a nitrogen gas cylinder 44 which are sequentially connected through a pipeline, the valve seven 41 is communicated with the air inlet chamber 131 through a pipeline, and when the nitrogen gas cylinder 44 delivers nitrogen gas into the caisson casing 11 and the inside of the pump body 19 through the air inlet chamber 131, the pressure regulator 43 regulates the pressure of the flowing nitrogen gas.

In this embodiment, valve seven 41, check valve two 42 and pressure regulator 43 are used for carrying and control nitrogen gas, blow off the caisson shell 11 inside through air inlet chamber 131, and pressure regulator 43 is used for giving the nitrogen gas decompression, avoids the pressure too high, and the velocity of flow is too fast harms equipment and extravagant air supply, accords with economic benefits, uses energy-concerving and environment-protective more.

In use, in the present scheme, only LPG and LNG media are taken as examples, the media may also be ethane, butane, ethylene and other media that need to be liquefied and stored at low temperature, the caisson component 1 can be used not only in a fuel tank but also in a transportation and storage tank, in the present scheme, the height and diameter of the caisson component 1, the type and size of the upper sealing plate 16 and the air inlet cavity 131, the sealing type and size of the upper base plate 12 and the lower base plate 14, and the like, all of which can be configured differently according to requirements, so as to meet the requirements of various ships in practical use, the initial state of the upper base plate 12 and the lower base plate 14 is a closed state, the nut 151 is rotated clockwise to abut against the top of the upper sealing plate 16, the screw 15 moves upward while driving the lower base plate 14 to move upward, so that the lower base plate 14 drives the trapezoidal sealing cone 141 to extend into the sealing cone groove 121, thereby 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 separate from the connection with the upper base plate 12, and the trapezoidal sealing cone 141 separates from the inside of the sealing cone groove 121, so that the caisson shell 11 is communicated with the fuel tank 2, and the device has the following use modes:

before the pump body 19 is overhauled and maintained, the upper base plate 12 and the lower base plate 14 are closed, the blowing pressure of nitrogen is adjusted through the pressure regulator 43, the valve seven 41, the valve one 31 and the valve two 32 are opened, the nitrogen is used for blowing LPG/LNG through the air inlet cavity 131, the LPG/LNG and the boil-off gas are blown from the interior of the caisson shell 11 to the suction port at the bottom end of the pump body 19, then the pipeline is conveyed along the interior of the pump shaft 191 to the pump outlet flange 18 and are released to the safe area of the ventilation mast 321 through the valve one 31 and the valve two 32, the phenomenon that the whole fuel tank 2 has a dead angle in the interior of the caisson during blowing operation to cause residue of the LPG/LNG is avoided, the blowing operation can be carried out by adjusting the nitrogen pressure to 6bar, and the hydrocarbon concentration detection is carried out by the portable detector at the pump outlet flange 18, and the detection of the concentration lower than 25 percent LEL is qualified, after inerting is finished, the inerting caisson function is blown off independently, accident potential can be eliminated more thoroughly, the caisson is opened again after blowing off, the pump is taken out for maintenance, the bolt for installing the upper component 17 is disassembled, and the pump body 19 can be vertically lifted out through the upper component 17 by using a crane of a shipyard;

the natural air in the caisson component 1 is replaced by nitrogen, after the pump body 19 is installed in the caisson shell 11, the natural air is in the caisson shell 11, the upper bottom plate 12 and the lower bottom plate 14 are closed and are in a sealed state, LPG/LNG is filled into the fuel tank 2 and the pump body 19 runs, the natural air in the caisson shell 11 can be opened through the air inlet cavity 131 and is flooded, the pressure of the pressure regulator 43 is regulated, the natural air in the caisson is replaced by nitrogen, the air is blown to the safe area of the ventilating mast 321 through the opening valve I31 and the valve II 32, the area of the caisson shell 11 is inerted by nitrogen, the phenomenon that water vapor in the natural air freezes after encountering low-temperature LPG/LNG and influences the running of the pump body 19 is avoided, the nitrogen needs to be dried, the dew point is lower than-8 ℃ when the fuel medium is LPG, the dew point is lower than-60 ℃, the content of O2 in the caisson shell 11 is measured by a portable instrument after the nitrogen replacement is carried out for a period of time, the replacement is completed, the process is similar to the process of blowing off the LPG/LNG vaporized gas for inerting in the previous step, only the use time is different, one is before the operation of maintaining the pump body 19, the other is before the operation of filling the LPG/LNG into the pump body 19, and in the operation of the mode, the valve III 33 is kept closed;

precooling the pump body 19, referring to fig. 4, the caisson external piping system 3 is composed of a first valve 31, a second valve 32, a ventilating mast 321, a third valve 33, a fourth valve 34, a gas return pipe 341, a first check valve 35, a fifth valve 36, a gas inlet pipe 361, a sixth valve 37 and a connecting pipe 38, the first valve 31 is connected with the pump outlet flange 18, the inlet gas enters the interior of the fuel tank 2 through the gas inlet pipe 361, the fifth valve 36, the sixth valve 37 and the connecting pipe 38, before the filling of LPG/LNG and the operation of the pump body 19, after the caisson module 1 is replaced with nitrogen, the caisson external piping system 3 can use the low temperature LPG/LNG boil-off gas to blow off nitrogen and precool the pump body 19, the pump shaft 191 and the pump impeller 192, and the temperature difference between the upper body and the lower body is gradually cooled within a tolerable temperature difference range, thereby avoiding the damage to the pump caused by the too large temperature difference between the upper position and the lower position, the low-temperature LPG/LNG evaporated gas comes from an external gas source station, is connected into the fuel tank 2 from a connecting pipe 38 by opening a valve five 36 and a valve six 37, an upper bottom plate 12 and a lower bottom plate 14 are opened, the evaporated gas enters an internal channel of the pump impeller 192 and moves upwards to reach a pump outlet flange 18, and returns to the evaporated gas source station by opening a valve one 31, a valve three 33, a valve four 34 and a gas return pipe 341, and a check valve one 35 ensures that the inlet gas does not enter a pump outlet pipeline, so that according to the flow, the low-temperature LPG/LNG evaporated gas can uniformly pre-cool the pump body 19, the pump shaft 191 and the pump impeller 192, and finally the temperature difference between the upper position and the lower position is within an allowable range;

the pressure test is similar to the nitrogen replacement process, except that the first valve 31 is closed, the upper base plate 12 and the lower base plate 14 are closed, the first pump outlet valve 31 is further closed, the seventh valve 41 is opened, nitrogen enters the caisson shell 11, the pressure regulator 43V6 is regulated to the test pressure, such as 6bar, the pressure is maintained for 15 minutes, and if no pressure drop exists, the tightness and strength of the caisson shell 11 are verified to be qualified through test.

In conclusion, according to the inertable low-temperature caisson device and the pipeline system thereof, by arranging the caisson component 1, the opening and closing of the upper base plate 12 and the lower base plate 14 can be controlled through the adjusting screw rod 15 and the nut 151, the caisson shell 11 is isolated from the fuel tank 2, the trapezoidal sealing cone 141 is matched with the sealing cone groove 121, the isolation sealing effect is further ensured, the structure is simple, the processing and production are facilitated, the economic benefit is met, and the inertable low-temperature caisson device and the pipeline system thereof have high universality.

It should be noted that, in this document, terms such as "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

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