LNG carrier tank vaporization gas recovery system

Abstract

The application discloses a LNG ship tank evaporated gas recovery system, which comprises a gas storage tank, a primary heat exchanger connected with the gas storage tank, a secondary heat exchanger connected with the gas storage tank and the primary heat exchanger, a gasifier connected with the secondary heat exchanger, a compressor connected with the secondary heat exchanger, a safety tank installed between the gas storage tank and the compressor, a natural gas generator connected with the safety tank, and a seawater extraction system connected with the safety tank and the primary heat exchanger. The LNG ship tank evaporated gas recovery system is characterized in that the compressed natural gas is converted into a gaseous state with low energy consumption through seawater heat exchange and a lifting mechanism arranged in the safety tank, so as to be used for secondary tank filling or natural gas generator power generation; and the first connecting mechanism and the second connecting mechanism of the safety tank are optimized and designed, the safety tank is conveniently disassembled and assembled as a whole, and the safety tank is conveniently transferred on the ship and flexibly used between secondary tank filling and natural gas generation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LNG boil-off gas treatment, in particular to a LNG ship tank loading boil-off gas recovery system. BACKGROUND

[0002] When LNG (liquefied natural gas) is stored in a low-temperature storage tank, heat exchange will inevitably occur due to factors such as sunlight, changes in ambient temperature, and the structure of the equipment itself, thus generating boil-off gas. In order to minimize the loss of LNG boil-off gas, the industry has proposed a process design that recovers the boil-off gas into nearby gas storage facilities or domestic pipelines for reuse.

[0003] Among them, for the gas storage facilities on the ship used to recover natural gas boil-off gas, the natural gas stored inside cannot be connected to the nearby domestic pipeline, so it can only be reloaded and returned to the low-temperature storage tank after secondary loading, making the reuse of natural gas boil-off gas on the ship single.

[0004] In addition, the existing ship gas storage facilities store natural gas in a liquid state under high-pressure and low-temperature conditions. When the natural gas in the gas storage facilities needs to be reused, the liquefied natural gas needs to be depressurized or warmed up in advance. The traditional method is to heat the liquid natural gas to form a gas state using a gasifier and use a pressure reducing pump to reduce the pressure. However, there is a problem of excessive energy consumption in the use of the gasifier and the pressure reducing pump, and it is difficult to completely rely on the power supply system of the ship LNG to drive, otherwise it will affect the normal operation of other functions on the ship. SUMMARY

[0005] The purpose of the present application is to provide a LNG ship tank loading boil-off gas recovery system to solve the problems raised in the background art.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] A LNG ship tank loading boil-off gas recovery system, comprising a gas storage tank, a primary heat exchanger connected in communication with the gas storage tank, a secondary heat exchanger connected in communication with the gas storage tank and the primary heat exchanger, a gasifier connected in communication with the secondary heat exchanger, a compressor connected in communication with the secondary heat exchanger, a safety tank installed between the gas storage tank and the compressor, a natural gas generator connected in communication with the safety tank, and a seawater extraction system connected in communication with the safety tank and the primary heat exchanger.

[0008] The safety tank is internally provided with a partition plate which can move up and down, the partition plate separates the inner cavity of the safety tank into a pressure reduction cavity and a gas storage cavity from top to bottom, the gas storage cavity is internally provided with a heat exchange pipe, both ends of the heat exchange pipe are provided with a center pipe, the center pipe comprises a hollow section and a solid section, the hollow section is integrally connected with the heat exchange pipe, the outer walls of both ends of the safety tank are respectively provided with a first connecting mechanism and a second connecting mechanism and are both provided with a rotary motor, the inner walls of both ends of the gas storage cavity are both provided with a guide groove and are both horizontally provided with a rotary pipe;

[0009] One end of the rotary pipe towards the inside of the safety tank is provided with an inner elbow joint, the other end of the inner elbow joint is communicated with the hollow section of the center pipe through a soft pipe, one end of the rotary pipe towards the outside of the safety tank is provided with an outer elbow joint, the other end of the outer elbow joint is communicated with the first connecting mechanism or the second connecting mechanism through an inner through pipe, the rotary pipe is rotatably connected with the inner wall of the safety tank through a mounting bearing, both ends of the rotary pipe are rotatably connected with the outer elbow joint and the inner elbow joint through connecting bearings, the outer lateral wall of the rotary pipe is fixedly sleeved with an upper gear, the upper gear is meshingly connected with a lower gear below, the lower gear is connected with the rotary motor.

[0010] The solid section of the center pipe is connected with a rectangular block, the rectangular block is provided with a sliding column, the sliding column is slidably connected with the guide groove, the outer lateral wall of the rotary pipe is fixedly sleeved with a swing rod, a sliding groove is formed through the swing rod, the rectangular block is slidably connected with the sliding groove.

[0011] Preferably, the partition plate moves up and down through a lifting mechanism, the lifting mechanism comprises a lifting column, a screw rod and a lifting motor, the lifting column is fixedly installed on the upper surface of the partition plate, the lifting column is internally provided with a threaded groove, the lifting motor is installed on the top of the safety tank, one end of the screw rod is inserted into the threaded groove and is threadedly connected with the lifting column, and the other end of the screw rod penetrates out of the safety tank and is connected with the lifting motor, the screw rod is rotatably connected with the top wall of the safety tank through a lifting bearing.

[0012] Preferably, the inner wall of the safety tank below the partition plate is provided with a supporting seat, the upper surface of the supporting seat is provided with a groove, the cross section of the groove is a right trapezoid, the lower surface of the partition plate is fixedly connected with a sealing seat, the sealing seat is positionally corresponding and shape-matched with the groove, the movable insertion between the sealing seat and the supporting seat is realized by moving the partition plate, and the supporting seat and the sealing seat are both rectangular frame bodies.

[0013] Preferably, the first connecting mechanism is provided with a seawater inlet pipe, a liquid nitrogen inlet pipe and a canned gas outlet pipe, one end of the seawater inlet pipe and the liquid nitrogen inlet pipe is communicated with the heat exchange pipe through an inner through pipe, the other end of the seawater inlet pipe is used for connecting a seawater extraction system, one end of the canned gas outlet pipe is communicated with the inner cavity of the safety tank through an inner through pipe and the other end is used for connecting a gas storage tank.

[0014] The second connecting mechanism is provided with a power generation gas outlet pipe, a seawater outlet pipe, a nitrogen gas outlet pipe and a recovery inlet pipe, one end of the seawater outlet pipe and the nitrogen gas outlet pipe is communicated with the heat exchange pipe through the inner through pipe, one end of the recovery inlet pipe and the power generation gas outlet pipe is communicated with the inner cavity of the safety tank through the inner through pipe, the other end of the recovery inlet pipe is used for connecting the compressor, and the other end of the power generation gas outlet pipe is used for connecting the natural gas generator.

[0015] Preferably, the first connecting mechanism and the second connecting mechanism each include a connecting plate and a cover plate, the connecting plate is fixedly connected to the outer wall of the safety tank, the cover plate is located on the side of the connecting plate away from the safety tank, a cylindrical seat and a sealing block are arranged between the connecting plate and the cover plate, the sealing block is fixedly connected to the cover plate, and the cylindrical seat is fixedly connected to the connecting plate.

[0016] The inside of the cylindrical seat is integrally penetrated, an inner through pipe is connected to the side close to the safety tank, a hollow groove is arranged in the middle, one or two insertion grooves are arranged on the side away from the safety tank, the insertion grooves are circular truncated cone-shaped and have a smaller diameter closer to the safety tank, the sealing block is in position correspondence and shape matching with the insertion grooves, the movable insertion between the sealing block and the insertion grooves is realized by moving the cover plate, the seawater inlet pipe, the liquid nitrogen inlet pipe, the canned gas outlet pipe, the power generation gas outlet pipe, the seawater outlet pipe, the nitrogen gas outlet pipe and the recovery inlet pipe all pass through the cover plate and are respectively inserted into the insertion grooves, and the sealing block is arranged in a ring shape along the outside wall of the insertion end of the seawater inlet pipe, the liquid nitrogen inlet pipe, the canned gas outlet pipe, the power generation gas outlet pipe, the seawater outlet pipe, the nitrogen gas outlet pipe and the recovery inlet pipe.

[0017] Preferably, the outside wall of the seawater inlet pipe, the liquid nitrogen inlet pipe, the canned gas outlet pipe, the power generation gas outlet pipe, the seawater outlet pipe, the nitrogen gas outlet pipe and the recovery inlet pipe is sleeved with a clamp, the middle part of the clamp is welded and fixed to the side of the cover plate away from the connecting plate, and bolts are arranged in the closed ends of the clamp and penetrate the ends.

[0018] Preferably, the cover plate is provided with a plurality of screw holes, the connecting plate is provided with a plurality of adjusting bearings at positions corresponding to the screw holes, a screw rod penetrates the screw holes, one end of the screw rod is rotatably connected to the connecting plate through the adjusting bearing, and the screw rod is threadedly connected to the cover plate through the screw holes, so that the cover plate is moved closer to or away from the connecting plate by rotating the screw rod.

[0019] Preferably, the guide groove is elliptical.

[0020] Preferably, the swing rod and the upper gear are respectively arranged on the two sides of the mounting bearing.

[0021] Preferably, the seawater extraction system comprises a seawater primary filter, the outlet pipe of the seawater primary filter is connected with a reverse osmosis filter, the outlet pipe of the reverse osmosis filter is connected with a refrigerator, a three-way valve is installed on the outlet pipe of the refrigerator, one outlet of the three-way valve is communicated with a seawater inlet pipe, and the other outlet of the three-way valve is communicated with a primary heat exchanger.

[0022] Compared with the prior art, the present application has at least the following beneficial effects:

[0023] 1、The heat exchange pipe and the compressor are arranged, the recovered natural gas evaporation gas is firstly partially compressed by the compressor, at this time, the evaporation gas is pressurized but does not reach the high pressure state in storage, then the pressurized evaporation gas enters the gas storage cavity of the safety tank from the recovery inlet pipe, liquid nitrogen is introduced into the liquid nitrogen inlet pipe, the liquid nitrogen enters the heat exchange pipe and fully contacts with the evaporation gas, so that the condensation cooling treatment of the evaporation gas is realized, and the method of low-cost compression and condensation combination is adopted to recover the natural gas evaporation gas and temporarily store it in the safety tank.

[0024] 2、The lifting mechanism is arranged, the screw rod is driven to rotate by the lifting motor, the screw rod drives the lifting column to rise through the thread groove, the lifting column drives the partition plate to move upward in the safety tank, so that the space of the gas storage cavity is increased, the compressed natural gas stored in the gas storage cavity is depressurized, and normal-temperature seawater is introduced into the seawater inlet pipe through the seawater extraction system, the seawater flows into the heat exchange pipe through the hollow groove, the inner pipe, the rotating pipe, the hose and the center pipe in sequence, the seawater exchanges heat with the compressed natural gas through the heat exchange pipe, the compressed natural gas is converted into gas through the depressurization and temperature rising operation, which is beneficial to subsequent secondary packaging or power generation for the natural gas generator, the safety tank provided by the present application has the functions of natural gas storage, depressurization and temperature rising, and the effect of one tank with multiple uses is achieved, and the energy consumption is effectively reduced.

[0025] 3、The first connecting mechanism and the second connecting mechanism are arranged, the cover plate is driven to move away from the connecting plate by rotating the screw rod, the cover plate drives the clamp to move, the clamp drives the plurality of pipelines to be pulled out from the slot, at this time, the bolts on the clamp can be loosened, so that the seawater inlet pipe, the liquid nitrogen inlet pipe, the packaging outlet pipe, the power generation outlet pipe, the seawater outlet pipe, the nitrogen outlet pipe and the recovery inlet pipe can be detached from the cover plate, the safety tank is convenient to disassemble and assemble as a whole, the safety tank is convenient to transfer on the ship and is convenient to use flexibly between the secondary packaging and the natural gas generator, and the multipurpose requirement in actual application is met.

[0026] 4、The present application sets up the rotating pipe and its associated structure, when the compressed natural gas is refrigerated by the liquid nitrogen or is heated by the normal temperature seawater, the rotating motor drives the lower gear, the upper gear, the rotating pipe and the swing lever to rotate in turn, the swing lever drives the rectangular block to rotate, the slide column connected with the rectangular block needs to move along the guide groove, so the rectangular block slides in the slide groove while rotating around the rotating pipe, that is, the rectangular block drives the heat exchange pipe to rotate and move along the elliptical track in the gas storage cavity, so that the heat exchange pipe fully contacts with the compressed natural gas in the gas storage cavity, and the heat exchange efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a whole structure schematic view of a LNG ship tank evaporated gas recovery system of the embodiment 1;

[0028] Figure 2 It is a front cut structure schematic view of the safety tank in the embodiment 1;

[0029] Figure 3 It is a side cut structure schematic view of the safety tank at the swing lever position in the embodiment 1;

[0030] Figure 4 It is a connection structure schematic view of the rotating motor and the heat exchange pipe in the embodiment 1;

[0031] Figure 5 It is a front cut structure schematic view of the first connecting mechanism in the embodiment 1;

[0032] Figure 6 It is a three-dimensional structure schematic view of the first connecting mechanism in the embodiment 1;

[0033] Figure 7 It is a front cut structure schematic view of the second connecting mechanism in the embodiment 1;

[0034] Figure 8 It is a split structure schematic view of the second connecting mechanism in the embodiment 1;

[0035] In the figure: 1, gas storage tank; 2, primary heat exchanger; 3, secondary heat exchanger; 4, gasifier; 5, compressor; 6, safety tank; 61, partition; 62, lifting mechanism; 621, lifting column; 622, threaded groove; 623, screw rod; 624, lifting bearing; 625, lifting motor; 63, support seat; 631, groove; 632, sealing seat; 64, pressure reduction cavity; 65, gas storage cavity; 66, heat exchange pipe; 67, rotating pipe; 671, mounting bearing; 672, outer elbow joint; 673, inner elbow joint; 674, connecting bearing; 675, hose; 676, central pipe; 677, upper gear; 678, lower gear; 679, rotating motor; 6710, rectangular block; 6711, sliding column; 6712, swing rod; 6713, sliding groove; 68, first connecting mechanism; 69, second connecting mechanism; 691, connecting plate; 692, cylindrical seat; 693, hollow groove; 694, inner through pipe; 695, insertion slot; 696, cover plate; 697, screw hole; 698, screw rod; 699, adjusting bearing; 6910, clamp; 6911, bolt; 6912, sealing block; 610, guide groove; 611, seawater inlet pipe; 612, liquid nitrogen inlet pipe; 613, canned gas outlet pipe; 614, power generation gas outlet pipe; 615, seawater outlet pipe; 616, nitrogen gas outlet pipe; 617, recovery inlet pipe; 7, natural gas generator; 8, seawater extraction system; 81, seawater primary filter; 82, reverse osmosis filter; 83, refrigerator; 84, three-way valve. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0038] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "connected" and the like should be understood in a broad sense, for example, "connected" can be fixedly connected, or detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] Embodiment 1

[0040] As Figures 1 to 8 shown, the present embodiment provides a LNG ship tank vapor recovery system, comprising a gas storage tank 1, a primary heat exchanger 2 connected with the gas storage tank 1, a secondary heat exchanger 3 connected with the gas storage tank 1 and the primary heat exchanger 2, a gasifier 4 connected with the secondary heat exchanger 3, a compressor 5 connected with the secondary heat exchanger 3, a safety tank 6 installed between the gas storage tank 1 and the compressor 5, a natural gas generator 7 connected with the safety tank 6, and a seawater extraction system 8 connected with the safety tank 6 and the primary heat exchanger 2.

[0041] The safety tank 6 is internally provided with a partition plate 61, the length and width dimensions of the partition plate 61 are adapted to the length and width dimensions of the inner cavity of the safety tank 6, the partition plate 61 divides the inner cavity of the safety tank 6 into a pressure reduction cavity 64 and a gas storage cavity 65, and the partition plate 61 is raised and lowered by a lifting mechanism 62 to adjust the space size of the gas storage cavity 65 and the pressure reduction cavity 64.

[0042] A support seat 63 is installed on the inner wall of the safety tank 6 below the partition plate 61, a heat exchange pipe 66 is arranged inside the gas storage cavity 65, the heat exchange pipe 66 adopts an S-shaped curved structure for contacting the compressed natural gas in the gas storage cavity 65 to realize heat exchange, both ends of the heat exchange pipe 66 are provided with a center pipe 676, the center pipe 676 comprises a hollow section and a solid section, the hollow section is integrally connected with the heat exchange pipe 66, a rotating pipe 67 is installed at the center of the inner wall at both ends of the gas storage cavity 65, and an oval guide groove 610 is also formed on the inner wall at both ends of the gas storage cavity 65.

[0043] A first connecting mechanism 68 and a rotating motor 679 are installed on the outer side wall of one end of the safety tank 6, and a second connecting mechanism 69 and a rotating motor 679 are installed on the outer side wall of the other end of the safety tank 6, the first connecting mechanism 68 and the second connecting mechanism 69 are used to realize the in-out of the heat exchange medium in the heat exchange pipe 66 and the in-out of the natural gas vapor in the gas storage cavity 65.

[0044] The rotating pipe 67 is horizontally arranged and rotationally connected with the inner side wall of the safety tank 6 through a mounting bearing 671. One end of the rotating pipe 67 towards the inside of the safety tank 6 is provided with an inner elbow joint 673. The other end of the rotating pipe 67 towards the outside of the safety tank 6 is provided with an outer elbow joint 672. The outer elbow joint 672 and the inner elbow joint 673 are both right-angle-shaped pipes and both communicate with the inner cavity of the rotating pipe 67. The two ends of the rotating pipe 67 are respectively rotationally connected with the outer elbow joint 672 and the inner elbow joint 673 through connecting bearings 674. The mounting bearing 671 and the connecting bearings 674 are both low-temperature-resistant and high-pressure-resistant sealed bearings, which can adapt to the special environment of high pressure and low temperature in the gas storage cavity 65. The other end of the inner elbow joint 673 is connected with a hose 675. The other end of the hose 675 is perpendicularly connected with the outer side wall of the hollow section of a center pipe 676, so as to realize the communication between the rotating pipe 67 and the heat exchange pipe 66. The other end of the outer elbow joint 672 is communicated with the first connecting mechanism 68 or the second connecting mechanism 69 through an inner through pipe 694.

[0045] On the side of the mounting bearing 671 towards the outside of the safety tank 6, the outer side wall of the rotating pipe 67 is fixedly sleeved with an upper gear 677. The lower side of the upper gear 677 is engaged with a lower gear 678. The lower gear 678 is connected with nearby rotating motors 679 in linkage. The two rotating motors 679 are synchronously driven through a circuit

[0046] On the side of the mounting bearing 671 towards the inside of the safety tank 6, the outer side wall of the rotating pipe 67 is fixedly sleeved with a swing rod 6712. The swing rod 6712 is provided with a sliding groove 6713. The solid section of the center pipe 676 is connected with a rectangular block 6710. The rectangular block 6710 is provided with a sliding column 6711. The sliding column 6711 is slidably connected with the guide groove 610. The rectangular block 6710 is slidably connected with the sliding groove 6713. It should be noted that the length of the hose 675 should meet the requirement that the normal communication function of the hose 675 is not affected when the sliding column 6711 moves to the most distant position of the two ends of the guide groove 610.

[0047] Further, the combination of the center pipe 676, the rectangular block 6710 and the sliding column 6711 penetrates the swing rod 6712. One end is slidably connected with the guide groove 610. The other end is connected with the heat exchange pipe 66. When the rotating pipe 67 drives the swing rod 6712 to rotate, the swing rod 6712 simultaneously drives the rectangular block 6710 to rotate. The sliding column 6711 connected with the rectangular block 6710 moves along the guide groove 610. Therefore, the rectangular block 6710 is dragged by the sliding column 6711 to rotate around the rotating pipe 67 and move in the sliding groove 6713. The rectangular block 6710 drives the heat exchange pipe 66 to move in the gas storage cavity 65 along an elliptical track by the center pipe 676. Thus, the heat exchange pipe 66 is fully contacted with the compressed natural gas in the gas storage cavity 65 to quickly perform heat exchange.

[0048] Further, the lifting mechanism 62 comprises lifting columns 621, screw rods 623 and lifting motors 625, the number of the lifting columns 621 is two and they are symmetrically distributed on the upper surface of the partition plate 61, the bottom of the lifting columns 621 is welded and fixed with the partition plate 61, the inside of the lifting columns 621 is provided with screw grooves 622, the number of the lifting motors 625 is two and they are symmetrically installed on the top of the safety tank 6, one end of the screw rod 623 is inserted into the screw groove 622 and threadedly connected with the lifting column 621, and the other end penetrates through the safety tank 6 and is connected with the lifting motor 625, the screw rod 623 is rotatably connected with the top wall of the safety tank 6 through a lifting bearing 624, the lifting bearing 624 uses a sealing bearing resistant to low temperature and high pressure, which can adapt to the special environment of high pressure and low temperature in the safety tank 6, and the two lifting motors 625 are synchronously driven through a circuit.

[0049] Further, the upper surface of the support base 63 is provided with a groove 631, the cross section of the groove 631 is a right trapezoid, the lower surface of the partition plate 61 is fixedly connected with a sealing seat 632, the sealing seat 632 is positionally corresponding and shape-matched with the groove 631, the movable insertion between the sealing seat 632 and the support base 63 is realized by moving the partition plate 61, and the support base 63 and the sealing seat 632 are both rectangular frame bodies. The sealing seat 632 uses a material resistant to low temperature and high pressure, for example, acrylate rubber, which can be used in the range of minus 25-170℃. The shape matching referred to in the present application means that the shapes of the two are the same and the sizes are consistent or the sizes are 0.5-2mm in excess. Specifically, in the present embodiment, the width size of the sealing seat 632 can be equal to or slightly larger than the width size of the groove 631, when the sealing seat 632 is inserted into the groove 631, the sealing seat 632 is extruded and deformed by the inner wall of the groove 631, so that the sealing seat 632 tightly adheres to the groove 631 and the inner wall of the safety tank 6, thereby realizing the sealing of the gap between the partition plate 61 and the inner wall of the safety tank 6.

[0050] Further, the first connecting mechanism 68 is provided with a seawater inlet pipe 611, a liquid nitrogen inlet pipe 612 and a tanked gas outlet pipe 613, one end of the seawater inlet pipe 611 and the liquid nitrogen inlet pipe 612 is communicated with the heat exchange pipe 66 through an inner through pipe 694, the other end of the seawater inlet pipe 611 is connected with a seawater extraction system 8, which is used for introducing seawater at normal temperature into the heat exchange pipe 66 to warm the compressed natural gas, the liquid nitrogen inlet pipe 612 is used for introducing liquid nitrogen into the heat exchange pipe 66 to cool the compressed natural gas, one end of the tanked gas outlet pipe 613 is communicated with the gas storage cavity 65 through the inner through pipe 694 and the other end is used for connecting the gas storage tank 1, the compressed natural gas stored in the safety tank 6 is introduced into the gas storage tank 1 through the tanked gas outlet pipe 613 to be used for secondary tanking.

[0051] The second connecting mechanism 69 is provided with a power generation gas outlet pipe 614, a seawater outlet pipe 615, a nitrogen gas outlet pipe 616 and a recovery inlet pipe 617. One end of the seawater outlet pipe 615 and the nitrogen gas outlet pipe 616 is communicated with the heat exchange pipe 66 through the inner through pipe 694. The seawater outlet pipe 615 is used for discharging seawater in the heat exchange pipe 66. The nitrogen gas outlet pipe 616 is used for discharging the vaporized nitrogen after being refrigerated. One end of the recovery inlet pipe 617 and the power generation gas outlet pipe 614 is communicated with the gas storage cavity 65 through the inner through pipe 694. The other end of the recovery inlet pipe 617 is used for connecting the compressor 5. The other end of the power generation gas outlet pipe 614 is used for connecting the natural gas generator 7.

[0052] The first connecting mechanism 68 and the second connecting mechanism 69 both include a connecting plate 691 and a cover plate 696. The connecting plate 691 is fixedly connected to the outer wall of the safety tank 6. The cover plate 696 is located on the side of the connecting plate 691 away from the safety tank 6. A cylindrical seat 692 and a sealing block 6912 are arranged between the connecting plate 691 and the cover plate 696. The sealing block 6912 is fixedly connected with the cover plate 696. The cylindrical seat 692 is fixedly connected with the connecting plate 691 or is integrally formed.

[0053] The inside of the cylindrical seat 692 is through as a whole. The inner through pipe 694 is connected to the side close to the safety tank 6. The hollow groove 693 is arranged in the middle. One or two insertion grooves 695 are arranged on the side away from the safety tank 6. The seawater inlet pipe 611, the liquid nitrogen inlet pipe 612, the canned gas outlet pipe 613, the power generation gas outlet pipe 614, the seawater outlet pipe 615, the nitrogen gas outlet pipe 616 and the recovery inlet pipe 617 correspond to the insertion grooves 695 one by one and are respectively inserted into the corresponding insertion grooves 695 through the cover plate 696. The seawater inlet pipe 611 and the liquid nitrogen inlet pipe 612 correspond to the insertion grooves 695 in the same cylindrical seat 692 and are communicated with the same hollow groove 693. The seawater outlet pipe 615 and the nitrogen gas outlet pipe 616 correspond to the insertion grooves 695 in the same cylindrical seat 692 and are communicated with the same hollow groove 693. The canned gas outlet pipe 613, the power generation gas outlet pipe 614 and the recovery inlet pipe 617 correspond to the cylindrical seats 692 with independent insertion groove structures.

[0054] The slot 695 is a circular truncated cone, and the closer to the safety tank 6, the smaller the diameter. The sealing block 6912 is arranged on the outer side wall of the insertion end of the seawater inlet pipe 611, the liquid nitrogen inlet pipe 612, the tank outlet gas pipe 613, the power generation outlet gas pipe 614, the seawater outlet pipe 615, the nitrogen outlet pipe 616 and the recovery inlet pipe 617 respectively, and the shape of the sealing block 6912 matches the slot 695. The movable insertion between the sealing block 6912 and the slot 695 is realized by moving the cover plate 696. When the sealing block 6912 is inserted into the slot 695, the sealing block 6912 is deformed by being pressed by the inner wall of the slot 695, so that the sealing block 6912 tightly adheres to the slot 695 and the outer wall of the pipe, thereby sealing the gap between the pipe and the cylindrical seat 692. At the same time, the friction between the sealing block 6912 and the inner wall of the slot 695 and the outer side wall of the pipe is increased, thereby achieving reinforcement between the pipe and the cover plate 696. In this embodiment, the material of the sealing block 6912 is ordinary rubber.

[0055] A plurality of screw holes 697 are arranged through the edge of the cover plate 696. A plurality of adjusting bearings 699 are arranged at positions corresponding to the screw holes 697 of the connecting plate 691. A screw rod 698 is arranged through the screw hole 697. One end of the screw rod 698 is rotatably connected to the connecting plate 691 through the adjusting bearing 699. The screw rod 698 is threadedly connected to the cover plate 696 through the screw hole 697. The cover plate 696 is moved close to or away from the connecting plate 691 by rotating the screw rod 698.

[0056] The outer side walls of the seawater inlet pipe 611, the liquid nitrogen inlet pipe 612, the tank outlet gas pipe 613, the power generation outlet gas pipe 614, the seawater outlet pipe 615, the nitrogen outlet pipe 616 and the recovery inlet pipe 617 are all sleeved with a clamp 6910. The middle part of the clamp 6910 is fixedly welded to the side of the cover plate 696 away from the connecting plate 691. Bolts 6911 are arranged through the closed two ends of the clamp 6910. The two ends of the clamp 6910 can be separated by disassembling the bolts 6911. When the cover plate 696 moves with the clamp 6910, the clamp 6910 simultaneously drives the plurality of pipes to be inserted into the corresponding slots 695, thereby realizing communication with the corresponding hollow grooves 693 and inner through pipes 694, or the clamp 6910 simultaneously drives the plurality of pipes to be extracted from the slots 695. The bolts 6911 on the clamp 6910 are loosened, so that the seawater inlet pipe 611, the liquid nitrogen inlet pipe 612, the tank outlet gas pipe 613, the power generation outlet gas pipe 614, the seawater outlet pipe 615, the nitrogen outlet pipe 616 and the recovery inlet pipe 617 can be quickly disassembled from the cover plate 696. This facilitates overall disassembly of the safety tank 6, facilitates transfer of the safety tank 6 on the ship and facilitates flexible use between the secondary tank and the natural gas generator 7.

[0057] It should be noted that the present application relates to a plurality of inner through pipes 694 and corresponding connection of each pipe, each of which is provided with a valve to ensure the sealing of the safety tank 6 when the safety tank 6 is disassembled. Among them, the seawater inlet pipe 611 and the liquid nitrogen inlet pipe 612 communicate with the same inner through pipe 694, and the seawater outlet pipe 615 and the nitrogen gas outlet pipe 616 also communicate with the same inner through pipe 694. When the compressed natural gas is stored, the liquid nitrogen is introduced into the heat exchange pipe 66 to cool the compressed natural gas, and when the compressed natural gas is used, the seawater at room temperature is introduced into the heat exchange pipe 66 to warm the compressed natural gas. The storage and use of the two states are not simultaneous, and the use of seawater warming and liquid nitrogen cooling does not interfere with each other. In addition, each pipe or the external pipe of each pipe is provided with a valve for internal flow control and liquid flow path control to ensure that seawater enters from the seawater inlet pipe 611 and is discharged from the seawater outlet pipe 615, and that liquid nitrogen enters from the liquid nitrogen inlet pipe 612 and nitrogen gas is discharged from the nitrogen gas outlet pipe 616.

[0058] Further, the seawater extraction system 8 comprises a seawater primary filter 81 for filtering the extracted seawater to remove large particles. The outlet pipe of the seawater primary filter 81 is connected with a reverse osmosis filter 82 for two-stage filtering of the seawater. The outlet pipe of the reverse osmosis filter 82 is connected with a refrigerator 83 for cooling the seawater. The outlet pipe of the refrigerator 83 is provided with a three-way valve 84. One outlet of the three-way valve 84 is connected with the seawater inlet pipe 611, and the other outlet of the three-way valve 84 is connected with the primary heat exchanger 2, so that the cooled seawater is divided by the three-way valve 84 and introduced into the primary heat exchanger 2 for heat exchange. It should be noted that when the seawater is used to warm the compressed natural gas in the gas storage cavity 65, the refrigerator 83 does not work, and the seawater at room temperature is directly introduced. At this time, there is a large temperature difference between the seawater and the compressed natural gas.

[0059] The use process of the LNG ship tank evaporation gas recovery system provided by the embodiment is as follows:

[0060] When it is necessary to recover the evaporated gas of the LNG tank, the seawater is filtered by the seawater primary filter 81, and then is filtered again by the reverse osmosis filter 82. After being refrigerated by the refrigerator 83, the seawater flows into the primary heat exchanger 2. The natural gas in the gas storage tank 1 is cooled by the primary heat exchanger 2 or directly enters the secondary heat exchanger 3. After that, the natural gas is vaporized by the gasifier 4 and is output for use. The evaporated gas generated during the storage and transportation is heated by the secondary heat exchanger 3, and then is partially compressed by the compressor 5. At this time, the evaporated gas is pressurized but has not reached a high pressure state that can be stored. The evaporated gas enters the storage cavity 65 from the recovery inlet pipe 617. At this time, liquid nitrogen is supplied to the liquid nitrogen inlet pipe 612. The liquid nitrogen enters the inner through pipe 694 through the corresponding hollow groove 693 on the first connecting mechanism 68, and then flows into the heat exchange pipe 66 through the outer elbow joint 672, the rotating pipe 67, the inner elbow joint, the hose 675 and the center pipe 676 in sequence, and fully contacts with the evaporated gas to condense and cool the evaporated gas.

[0061] At the same time, the rotating motor 679 drives the lower gear 678 to rotate, the lower gear 678 drives the upper gear 677 to rotate, the upper gear 677 drives the rotating pipe 67 to rotate, the rotating pipe 67 drives the swing rod 6712 to rotate, and the swing rod 6712 drives the rectangular block 6710 to rotate. Since the rectangular block 6710 is limited by the slide column 6711 connected thereto to slide in the guide groove 610, the rectangular block 6710 slides in the sliding groove 6713 while moving along the guide groove 610. The rectangular block 6710 drives the heat exchange pipe 66 to rotate and move along an elliptical trajectory in the storage cavity 65 through the center pipe 676. The trajectory is beneficial to the full contact between the heat exchange pipe 66 and the compressed natural gas in the storage cavity 65, so that rapid heat exchange is realized.

[0062] When it is necessary to use the stored compressed natural gas, the screw rod 623 is driven to rotate by the lifting motor 625, the screw rod 623 drives the lifting column 621 to rise through the threaded groove 622, and the lifting column 621 drives the partition plate 61 to move upwards in the safety tank 6, so that the space of the storage cavity 65 is increased. At this time, the pressure of the compressed natural gas stored in the storage cavity 65 is reduced. At the same time, the seawater is treated by the seawater primary filter 81 and the reverse osmosis filter 82, and then is supplied to the seawater inlet pipe 611 without being refrigerated. The seawater at normal temperature enters the inner through pipe 694 through the corresponding hollow groove 693 on the first connecting mechanism 68, and then flows into the heat exchange pipe 66 through the outer elbow joint 672, the rotating pipe 67, the inner elbow joint, the hose 675 and the center pipe 676 in sequence, and exchanges heat with the low-temperature compressed natural gas. The compressed natural gas is vaporized into gas after being depressurized and warmed up. Finally, the compressed natural gas is supplied to the gas storage tank 1 through the tank outlet pipe 613 for secondary tank storage, or is supplied to the natural gas generator 7 through the power generation outlet pipe 614 to generate electricity in combination with the recovered natural gas, so as to meet the power supply demand on the ship.

[0063] In the above process of using the compressed natural gas stored in the storage tank 1, the safety tank 6 needs to be moved to the side of the storage tank 1 or the natural gas generator 7, so the safety tank 6 needs to be disassembled for transfer. First, close the valve on each inner pipe 694, then rotate the screw rod 698, which rotates in the screw hole 697 to drive the cover plate 696 away from the connecting plate 691. The cover plate 696 moves the clamp 6910, which moves the multiple pipes out of the slot 695. Loosen the bolts 6911 on the clamp 6910, so that the seawater inlet pipe 611, the liquid nitrogen inlet pipe 612, the tank outlet gas pipe 613, the power generation outlet gas pipe 614, the seawater outlet pipe 615, the nitrogen gas outlet pipe 616 and the recovery inlet pipe 617 can be disassembled from the cover plate 696. This facilitates the overall disassembly of the safety tank 6 and facilitates the transfer on the ship.

[0064] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for limiting the present application, although the foregoing detailed description of the present application is made with reference to the foregoing embodiments, for those skilled in the art, it still can be modified, or part of the technical features of the equivalent replacement. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. An LNG carrier tank-primed boil-off gas recovery system characterized by: The application relates to a natural gas storage and utilization system, which comprises a gas storage tank (1), a primary heat exchanger (2) connected with the gas storage tank (1), a secondary heat exchanger (3) connected with the gas storage tank (1) and the primary heat exchanger (2), a gasifier (4) connected with the secondary heat exchanger (3), a compressor (5) connected with the secondary heat exchanger (3), a safety tank (6) installed between the gas storage tank (1) and the compressor (5), a natural gas generator (7) connected with the safety tank (6), and a seawater extraction system (8) connected with the safety tank (6) and the primary heat exchanger (2). The safety tank (6) is internally provided with a movable partition plate (61), which divides the safety tank (6) into a pressure reduction cavity (64) and a gas storage cavity (65) from top to bottom; the gas storage cavity (65) is internally provided with heat exchange pipes (66); the two ends of each heat exchange pipe (66) are provided with central pipes (676); the central pipes (676) comprise hollow sections and solid sections; the hollow sections are integrally connected with the heat exchange pipes (66); the outer walls of the two ends of the safety tank (6) are respectively provided with first connecting mechanisms (68) and second connecting mechanisms (69) and are provided with rotary motors (679); the inner walls of the two ends of the gas storage cavity (65) are respectively provided with guide grooves (610) and are horizontally provided with rotary pipes (67). One end of each rotary pipe (67) towards the inside of the safety tank (6) is provided with an inner elbow pipe joint (673); the other end of each inner elbow pipe joint (673) is connected with the hollow sections of the central pipes (676) through a hose (675); one end of each rotary pipe (67) towards the outside of the safety tank (6) is provided with an outer elbow pipe joint (672); the other end of each outer elbow pipe joint (672) is connected with the first connecting mechanisms (68) or the second connecting mechanisms (69) through an inner through pipe (694); each rotary pipe (67) is rotatably connected with the inner wall of the safety tank (6) through a mounting bearing (671); the two ends of each rotary pipe (67) are rotatably connected with the outer elbow pipe joints (672) and the inner elbow pipe joints (673) through connecting bearings (674); the outer lateral walls of the rotary pipes (67) are fixedly sleeved with upper gears (677); the lower gears (678) are connected with the upper gears (677) in a meshing mode; the lower gears (678) are connected with the rotary motors (679) in a linkage mode. The solid sections of the central pipes (676) are connected with rectangular blocks (6710); the rectangular blocks (6710) are provided with slide columns (6711); the slide columns (6711) are slidably connected with the guide grooves (610); the outer lateral walls of the rotary pipes (67) are fixedly sleeved with swing rods (6712); the swing rods (6712) are provided with slide grooves (6713) penetratingly formed in the swing rods (6712); the rectangular blocks (6710) are slidably connected with the slide grooves (6713).

2. The LNG carrier tank vaporization gas recovery system of claim 1, wherein: The partition plate (61) moves up and down through a lifting mechanism (62), the lifting mechanism (62) comprises a lifting column (621), a screw rod (623) and a lifting motor (625), the lifting column (621) is fixedly installed on the upper surface of the partition plate (61), the lifting column (621) is internally provided with a threaded groove (622), the lifting motor (625) is installed on the top of the safety tank (6), one end of the screw rod (623) is inserted into the threaded groove (622) and threadedly connected with the lifting column (621), and the other end penetrates out of the safety tank (6) and is connected with the lifting motor (625) in a linkage mode, and the screw rod (623) is rotatably connected with the top wall of the safety tank (6) through a lifting bearing (624).

3. The LNG carrier tank vaporization gas recovery system of claim 1, wherein: A supporting seat (63) is installed on the inner wall of the safety tank (6) below the partition plate (61), the upper surface of the supporting seat (63) is provided with a groove (631), the cross section of the groove (631) is a right trapezoid, the lower surface of the partition plate (61) is fixedly connected with a sealing seat (632), the sealing seat (632) is in position correspondence with the groove (631) and is shape-matched, the movable insertion between the sealing seat (632) and the supporting seat (63) is realized by moving the partition plate (61), and the supporting seat (63) and the sealing seat (632) are both rectangular frame bodies.

4. The LNG carrier tank vaporization gas recovery system of claim 1, wherein: The first connecting mechanism (68) is provided with a seawater inlet pipe (611), a liquid nitrogen inlet pipe (612) and a canned gas outlet pipe (613), one end of the seawater inlet pipe (611) and the liquid nitrogen inlet pipe (612) is communicated with the heat exchange pipe (66) through an inner through pipe (694), the other end of the seawater inlet pipe (611) is used for connecting a seawater extraction system (8), and one end of the canned gas outlet pipe (613) is communicated with the inner cavity of the safety tank (6) through the inner through pipe (694) and the other end is used for connecting a gas storage tank (1). The second connecting mechanism (69) is provided with a power generation gas outlet pipe (614), a seawater outlet pipe (615), a nitrogen gas outlet pipe (616) and a recovery gas inlet pipe (617), one end of the seawater outlet pipe (615) and the nitrogen gas outlet pipe (616) is communicated with the heat exchange pipe (66) through the inner through pipe (694), one end of the recovery gas inlet pipe (617) and the power generation gas outlet pipe (614) is communicated with the inner cavity of the safety tank (6) through the inner through pipe (694), the other end of the recovery gas inlet pipe (617) is used for connecting a compressor (5), and the other end of the power generation gas outlet pipe (614) is used for connecting a natural gas generator (7).

5. The LNG carrier tank vapor recovery system of claim 4, wherein: The first connecting mechanism (68) and the second connecting mechanism (69) each comprise a connecting plate (691) fixedly connected to the outer wall of the safety tank (6) and a cover plate (696) located on the side of the connecting plate (691) away from the safety tank (6), and a cylindrical seat (692) and a sealing block (6912) are arranged between the connecting plate (691) and the cover plate (696), the sealing block (6912) is fixedly connected to the cover plate (696), and the cylindrical seat (692) is fixedly connected to the connecting plate (691); The inside of the cylindrical seat (692) is entirely through, an inner through pipe (694) is connected to the side close to the safety tank (6), a hollow groove (693) is arranged in the middle, and one or two insertion grooves (695) are arranged on the side away from the safety tank (6), the insertion grooves (695) are circular truncated cone-shaped and become smaller in diameter as they are closer to the safety tank (6), the sealing block (6912) is in position correspondence and shape matching with the insertion grooves (695), the movable insertion between the sealing block (6912) and the insertion grooves (695) is realized by moving the cover plate (696), the seawater inlet pipe (611), the liquid nitrogen inlet pipe (612), the tank outlet gas pipe (613), the power generation outlet gas pipe (614), the seawater outlet pipe (615), the nitrogen gas outlet pipe (616) and the recovery inlet pipe (617) all pass through the cover plate (696) and are respectively inserted into the insertion grooves (695), and the sealing block (6912) is arranged annularly on the outer side wall of the insertion end of the seawater inlet pipe (611), the liquid nitrogen inlet pipe (612), the tank outlet gas pipe (613), the power generation outlet gas pipe (614), the seawater outlet pipe (615), the nitrogen gas outlet pipe (616) and the recovery inlet pipe (617).

6. The LNG carrier tank vaporization gas recovery system of claim 5, wherein: The outer side walls of the seawater inlet pipe (611), the liquid nitrogen inlet pipe (612), the tank outlet gas pipe (613), the power generation outlet gas pipe (614), the seawater outlet pipe (615), the nitrogen gas outlet pipe (616) and the recovery inlet pipe (617) are all sleeved with a clamp (6910), the middle part of the clamp (6910) is welded and fixed to the side of the cover plate (696) away from the connecting plate (691), and bolts (6911) are arranged in the closed ends of the clamp (6910) in a penetrating manner, so that the separation of the two ends of the clamp (6910) is realized by disassembling the bolts (6911).

7. The LNG carrier tank vapor recovery system of claim 5, wherein: The cover plate (696) is provided with a plurality of screw holes (697), the connecting plate (691) is provided with a plurality of adjusting bearings (699) at positions corresponding to the screw holes (697), a screw rod (698) is arranged in the screw holes (697) in a penetrating manner, one end of the screw rod (698) is rotatably connected to the connecting plate (691) through the adjusting bearing (699), and the screw rod (698) is threadedly connected to the cover plate (696) through the screw holes (697), so that the cover plate (696) is moved closer to or away from the connecting plate (691) by rotating the screw rod (698).

8. The LNG carrier tank vaporization gas recovery system of claim 1, wherein: The guide groove (610) is elliptical.

9. The LNG carrier tank vaporization gas recovery system of claim 1, wherein: The swing lever (6712) and the upper gear (677) are arranged on both sides of the mounting bearing (671) respectively.

10. The LNG carrier tank vaporization gas recovery system of claim 4, wherein: The seawater extraction system (8) comprises a seawater primary filter (81), a reverse osmosis filter (82) connected to a water outlet pipe of the seawater primary filter (81), a refrigerator (83) connected to a water outlet pipe of the reverse osmosis filter (82), and a triangular valve (84) installed on a water outlet pipe of the refrigerator (83), wherein one water outlet of the triangular valve (84) is communicated with a seawater inlet pipe (611), and another water outlet of the triangular valve (84) is communicated with a primary heat exchanger (2).

Images