Double-walled lng cryogenic pipe and cooling and drying device thereof

Abstract

The application discloses a double-wall LNG cryogenic pipe and a cooling and drying device thereof, and relates to the field of LNG transportation. The double-wall LNG cryogenic pipe comprises an outer thermal insulation pipe and an inner cryogenic pipe, and the outer thermal insulation pipe is sleeved on the inner cryogenic pipe. Further, the double-wall LNG cryogenic pipe comprises connecting flanges which are symmetrically fixedly installed at two end openings of the outer thermal insulation pipe. Front and rear annular sealing plates are symmetrically fixedly installed at two end openings in the outer thermal insulation pipe, and the inner cryogenic pipe is sealingly inserted between the front and rear annular sealing plates. Compared with the double-wall cryogenic pipe in the prior art, when the inner cryogenic pipe in the double-wall cryogenic pipe needs to be overhauled or replaced after long-time use, the inner cryogenic pipe can be quickly taken out from the outer thermal insulation pipe, so that the inner cryogenic pipe can be quickly maintained, overhauled or replaced by the staff, and the work efficiency is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of LNG transportation technology, specifically, it relates to a double-walled LNG cryogenic pipe and its cooling and drying device. Background Technology

[0002] Liquefied natural gas (LNG) is mainly composed of methane and is widely recognized as the cleanest fossil fuel on Earth. It is colorless, odorless, non-toxic, and non-corrosive. Its volume is approximately 1 / 625th that of the same amount of gaseous natural gas, and its mass is only about 45% of that of the same volume of water. The manufacturing process involves purifying natural gas produced from gas fields, followed by a series of cryogenic liquefaction processes, and then transporting it using LNG carriers. LNG combustion produces very little air pollution and releases a large amount of heat, making it a relatively advanced energy source.

[0003] For cryogenic pipelines used in LNG carriers, traditional technologies typically employ stainless steel insulation materials to transport cryogenic media. However, this makes it difficult to monitor for leaks, and prolonged operation can lead to pipeline aging and poor insulation performance. Therefore, existing technologies often use double-walled pipes for LNG transport. Existing double-walled LNG cryogenic pipes consist of an outer pipe, an inner pipe, and an insulation layer (such as expanded perlite) between them. However, after prolonged use, to ensure stable LNG transport, the inner and outer pipes require maintenance or replacement. When damage to the inner pipe necessitates replacement, the insulation material between the inner and outer pipes must be removed before the inner pipe can be easily retrieved, which is inconvenient and reduces work efficiency. Therefore, this invention is proposed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a double-walled LNG cryogenic pipe and its cooling and drying device that can overcome or at least partially solve the above problems.

[0005] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows: a double-walled LNG cryogenic pipe, comprising an outer insulation pipe and an inner cryogenic pipe, wherein the outer insulation pipe is sleeved on the inner cryogenic pipe, and further comprising: connecting flanges, symmetrically fixedly installed at the two end openings of the outer insulation pipe; a front annular sealing plate and a rear annular sealing plate, symmetrically fixedly installed at the two end openings inside the outer insulation pipe, wherein the inner cryogenic pipe is sealed and inserted between the front annular sealing plate and the rear annular sealing plate; multiple annular partitions, sliding within the insulation cavity formed by the outer insulation pipe, the front annular sealing plate, the rear annular sealing plate, and the inner cryogenic pipe, wherein the annular partitions are sealed and slidingly attached to the outer insulation pipe and the inner cryogenic pipe; every two annular partitions... Connecting ropes are fixedly connected between the plates and between the front annular sealing plate and the adjacent annular partition plate; two vent holes are symmetrically opened on each of the multiple annular partition plates away from the rear annular sealing plate, and a first one-way valve with opposite flow directions is installed in each of the two vent holes on each annular partition plate; a push rod is symmetrically rotatably connected to the side of the annular partition plate near the front annular sealing plate by a torsion spring, and the front annular sealing plate and the annular partition plate are respectively provided with inclined grooves that match the push rod; a pulling assembly for pulling the multiple annular partition plates to move forward annular sealing plate is installed on the outer insulation pipe; a first air supply pipe is installed on the outer insulation pipe near the front annular sealing plate and is connected to the insulation cavity.

[0006] Furthermore, the pulling assembly includes a pull rope and a rope take-up reel assembly. The rope take-up reel assembly is symmetrically installed on the outer insulation pipe near the front annular sealing plate. One end of the pull rope is fixedly connected to the rope take-up reel on the rope take-up reel assembly. The end of the pull rope that extends away from the rope take-up reel assembly and into the insulation cavity is fixedly connected to an annular partition near the rear annular sealing plate. The pull rope passes sequentially through multiple annular partitions away from the rear annular sealing plate. The central shaft on the rope take-up reel assembly is connected to the output end of the external drive unit via a ratchet.

[0007] To extend the service life of the pull ropes and prevent gas leakage in the insulation cavity, furthermore, protective rollers are symmetrically installed on the inner wall of the outer insulation pipe near the front annular sealing plate, and the two pull ropes are respectively wound around the adjacent protective rollers.

[0008] To facilitate sealing of the gaps between the interconnected inner cryogenic tubes, an annular airbag ring is fixedly connected to the side of the rear annular sealing plate away from the annular partition. The annular airbag ring is fitted onto the inner cryogenic tube, and the rear annular sealing plate and the annular airbag ring are respectively provided with interconnecting air supply holes.

[0009] To facilitate automatic cessation of the supply of inert gas into the insulated cavity, a first conductive plate is fixedly installed on the annular partition near the rear annular sealing plate, and a second conductive plate matching the first conductive plate is fixedly installed on the rear annular sealing plate. A first solenoid valve is installed inside the first gas supply pipe, and the second conductive plate is electrically connected to the first solenoid valve.

[0010] To further prevent scratches on the inner cryogenic tube, a protective rubber head is fixedly connected to the end of the abutment that abuts against the inner cryogenic tube.

[0011] To prevent the front annular sealing plate, rear annular sealing plate, and annular partition from transmitting temperature, the front annular sealing plate, rear annular sealing plate, and annular partition are all coated with a heat-insulating coating.

[0012] To ensure that liquefied natural gas remains at a low temperature and in a liquefied state, a cooling and drying device is provided for a double-walled LNG cryogenic pipe, including a heat exchange pipe installed on the inner wall of the inner cryogenic pipe. An annular storage tank is fixedly installed on the outer wall of the outer insulation pipe. The annular storage tank is connected to the heat exchange pipe through a second gas transmission pipe, and a second solenoid valve is installed inside the second gas transmission pipe.

[0013] To further facilitate more thorough heat exchange between liquefied natural gas and cryogenic helium, the heat exchange tube is spirally coiled around the inner wall of the inner cryogenic tube.

[0014] To extend the service life of the annular airbag ring and ensure its sealing effect at the interface, an annular drying plate is further fixedly connected to the side of the connecting flange away from the external insulation pipe, and the annular drying plate is sleeved on the outside of the annular airbag ring.

[0015] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: The present invention, through the combined use of the front and rear annular sealing plates, can form an insulation cavity between the outer insulation pipe and the inner cryogenic pipe. By setting multiple annular baffles and multiple connecting ropes of the same length within the insulation cavity, when inert gas is introduced into the insulation cavity through the first gas supply pipe to insulate the inner cryogenic pipe, the annular baffles can be arranged at equal intervals within the insulation cavity, thus providing support for the inner cryogenic pipe. This prevents excessive stress in the middle of the inner cryogenic pipe due to its length, which could lead to bending and damage, thus effectively improving the service life of the inner cryogenic pipe. Simultaneously, a stop bar is installed on the annular baffle using a torsion spring. When the rope reel assembly pulls the annular baffle to recover helium, the inner cryogenic pipe can be removed from the outer insulation pipe via the stop bar, facilitating quick maintenance, repair, or replacement of the inner cryogenic pipe by workers, effectively improving work efficiency.

[0016] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a front-view three-dimensional structural diagram of a double-walled LNG cryogenic pipe and its cooling and drying device proposed in this invention;

[0018] Figure 2 This is a rear-view three-dimensional structural diagram of a double-walled LNG cryogenic pipe and its cooling and drying device proposed in this invention;

[0019] Figure 3 This invention provides a cross-sectional perspective view of the outer insulation pipe, inner cryogenic pipe, annular partition, heat exchange pipe, front annular sealing plate, rear annular sealing plate, and annular storage tank in a double-walled LNG cryogenic pipe and its cooling and drying device. Figure 1 ;

[0020] Figure 4 This invention provides a cross-sectional perspective view of the outer insulation pipe, inner cryogenic pipe, annular partition, heat exchange pipe, front annular sealing plate, rear annular sealing plate, and annular storage tank in a double-walled LNG cryogenic pipe and its cooling and drying device. Figure 2 ;

[0021] Figure 5 This is a three-dimensional structural diagram of the inner cryogenic pipe, front annular sealing plate, rear annular sealing plate, annular partition, connecting rope, pull rope, protective roller and annular airbag ring in a double-walled LNG cryogenic pipe and its cooling and drying device proposed in this invention.

[0022] Figure 6This is a three-dimensional structural diagram of the annular partition, pull rope, connecting rope, first one-way valve, and push rod in a double-walled LNG cryogenic pipe and its cooling and drying device proposed in this invention.

[0023] Figure 7 This invention proposes a double-walled LNG cryogenic pipe and its cooling and drying device. Figure 6 A schematic diagram of the structure of part A;

[0024] Figure 8 This is a three-dimensional structural diagram of the annular airbag ring, the rear annular sealing plate, the annular partition plate, and the first conductive sheet in a double-walled LNG cryogenic pipe and its cooling and drying device proposed in this invention.

[0025] Figure 9 This is a three-dimensional structural diagram of the annular airbag ring, the rear annular sealing plate, the annular partition plate, and the second conductive sheet in a double-walled LNG cryogenic pipe and its cooling and drying device proposed in this invention.

[0026] In the diagram: 1. External insulation pipe; 101. Connecting flange; 102. Front annular sealing plate; 103. Rear annular sealing plate; 1031. Second conductive sheet; 104. Annular drying plate; 105. Protective roller; 2. Inner low-temperature pipe; 3. Annular partition; 301. Vent hole; 302. First conductive sheet; 303. Support rod; 3031. Protective rubber head; 4. Pull rope; 5. Connecting rope; 6. Rope winding reel; 7. Annular airbag ring; 8. Annular storage box; 801. First gas supply pipe; 802. Second gas supply pipe; 803. Heat exchange pipe; 804. Recovery pipe; 805. Refrigeration compressor. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0028] Example 1: Refer to Figures 1-9A double-walled LNG cryogenic pipe includes an outer insulation pipe 1 and an inner cryogenic pipe 2, with the outer insulation pipe 1 sleeved on the inner cryogenic pipe 2. It also includes: connecting flanges 101, symmetrically fixedly installed at both ends of the outer insulation pipe 1; a front annular sealing plate 102 and a rear annular sealing plate 103, symmetrically fixedly installed at both ends of the outer insulation pipe 1; and the inner cryogenic pipe 2 is sealed and inserted between the front annular sealing plate 102 and the rear annular sealing plate 103. Multiple annular partitions 3 slide within the insulation cavity formed by the outer insulation pipe 1, the front annular sealing plate 102, the rear annular sealing plate 103, and the inner low-temperature pipe 2. The annular partitions 3 are sealed and slide in contact with the outer insulation pipe 1 and the inner low-temperature pipe 2. Connecting ropes 5 are fixedly connected between every two annular partitions 3 and between the front annular sealing plate 102 and the adjacent annular partitions 3. Two vent holes 301 are symmetrically opened on each of the multiple annular partitions 3 away from the rear annular sealing plate 103. A first one-way valve with the opposite flow direction is installed in each of the two vent holes 301 on each annular partition 3. The abutment rod 303 is symmetrically connected to the side of the annular partition 3 near the front annular sealing plate 102 by a torsion spring. The front annular sealing plate 102 and the annular partition 3 are respectively provided with inclined grooves that match the abutment rod 303. The pulling assembly for pulling multiple annular partitions 3 to move forward to the annular sealing plate 102 is installed on the outer insulation pipe 1. The first air supply pipe 801 is installed on the outer insulation pipe 1 near the front annular sealing plate 102 and is connected to the insulation cavity.

[0029] The pulling assembly includes a pull rope 4 and a rope take-up reel assembly 6, which is symmetrically installed on the outer insulation pipe 1 near the front annular sealing plate 102. One end of the pull rope 4 is fixedly connected to the rope take-up reel on the rope take-up reel assembly 6. The end of the pull rope 4, away from the rope take-up reel assembly 6 and extending into the insulation cavity, is fixedly connected to the annular partition 3 near the rear annular sealing plate 103. The pull rope 4 passes sequentially through multiple annular partitions 3 away from the rear annular sealing plate 103. The central shaft on the rope take-up reel assembly 6 is connected to the output end of the external drive unit via a ratchet.

[0030] When assembling the double-walled cryogenic pipes for liquefied natural gas, the workers first move the inner cryogenic pipe 2 from the side near the front annular sealing plate 102 into the outer insulation pipe 1. Once the inner cryogenic pipe 2 is in place, multiple outer insulation pipes 1, each containing an inner cryogenic pipe 2, can be spliced ​​together using connecting flanges 101. After every two outer insulation pipes 1 are assembled together, the inner cryogenic pipes 2 will be tightly fitted together. After multiple sets of double-walled cryogenic pipes are installed, inert gas can then be supplied through the first gas transmission pipe 801 into the insulation cavity formed by the outer insulation pipe 1, the front annular sealing plate 102, the rear annular sealing plate 103, and the inner cryogenic pipe 2. The inert gas filled inside the double-walled cryogenic tube can be helium. By filling the insulation cavity with helium, which is less dense than air and has stable properties, it can not only act as a cryogenic refrigerant to keep liquefied natural gas cold, thus improving the insulation effect, but also support the inner cryogenic tube 2, improving its overall stability. This prevents excessive stress in the middle of the inner cryogenic tube 2 due to its length, which could lead to bending and damage, thus effectively extending the service life of the inner cryogenic tube 2.

[0031] When the first gas supply pipe 801 delivers helium into the insulated cavity, the helium first enters the cavity between the front annular sealing plate 102 and the adjacent annular partition 3. As the helium pressure increases, the annular partition 3 gradually moves to one side of the rear annular sealing plate 103. Since the central shaft on the rope winding reel 6 is connected to the output end of the external drive unit via a ratchet, when the annular partition 3 moves away from the rope winding reel 6, the rope winding reel 6 will idle and release the rope. When the connecting rope 5 between the annular partition 3 near the front annular sealing plate 102 and the front annular sealing plate 102 is tightened, this annular partition 3 will be limited and fixed. As the helium pressure increases, when the pressure exceeds the opening pressure of the first one-way valve in the vent 301, the helium will pass through the vent 301 and enter between the next annular partition 3 and the limited and fixed annular partition 3, thereby driving the next annular partition 3 to move. Since the multiple connecting ropes 5 are of the same length, when each connecting rope 5 is taut, the multiple annular partitions 3 will be arranged at equal intervals in the insulation cavity, which can further support the inner low-temperature tube 2 and improve the overall strength of the inner low-temperature tube 2.

[0032] When the inner cryogenic pipe 2 is damaged or needs to be repaired to ensure the stability of liquefied natural gas transportation, the section of the double-wall cryogenic pipe that needs to be replaced or repaired is first separated from the double-wall cryogenic pipes connected at both ends. Then, the first solenoid valve in the first gas transmission pipe 801 can be opened again. Then, the external drive unit controls the rope winding reel group 6 to reverse and wind up the pull rope 4. The rope winding reel group 6 will then pull multiple sets of annular partitions 3 sequentially towards the side closer to the front annular sealing plate 102 through the pull rope 4. Then, the helium in the insulation cavity will flow towards the position closer to the front annular sealing plate 102 through another set of first one-way valves. Thus, the helium can be recovered again through the first gas transmission pipe 801, effectively reducing the waste of helium and saving operating costs.

[0033] Meanwhile, when the annular baffle 3 is pulled by the rope 4, since the abutment rod 303 does not initially abut against the inner cryogenic tube 2, the helium gas in the insulation cavity will be squeezed and recovered when the annular baffle 3 moves the abutment rod 303. When the abutment rod 303 moves into the matching inclined groove, it will abut against the inner cryogenic tube 2 under the action of the inclined groove. Thus, while the annular baffle 3 is being pulled to recover the helium gas, the inner cryogenic tube 2 can be removed from the outer insulation tube 1. Then, the staff can maintain, repair, and replace the inner cryogenic tube 2, effectively improving the work efficiency of the staff, so that the double-walled cryogenic tube can be quickly put back into use.

[0034] Example 2: Refer to Figures 1-9 A double-walled LNG cryogenic pipe, basically the same as in Example 1, but with a further improvement: protective rollers 105 are symmetrically installed on the inner wall of the outer insulation pipe 1 near the front annular sealing plate 102. Two pull ropes 4 are respectively wound around the adjacent protective rollers 105. The protective rollers 105 protect the pull ropes 4 and the outer insulation pipe 1, preventing wear between the pull ropes 4 and the outer insulation pipe 1 during movement, thus avoiding breakage of the pull ropes 4 and expansion of the through holes on the outer insulation pipe 1. This effectively extends the service life of the pull ropes 4 and prevents leakage of inert gas in the insulation cavity.

[0035] An annular gasket ring 7 is fixedly connected to the side of the rear annular sealing plate 103 away from the annular partition 3, and the annular gasket ring 7 is sleeved on the inner cryogenic tube 2. The rear annular sealing plate 103 and the annular gasket ring 7 are respectively provided with interconnecting air inlets. When inert gas is introduced into the insulation cavity to move the annular partition 3, the gas in the insulation cavity between the rear annular sealing plate 103 and the annular partition 3 will be squeezed by the annular partition 3 and enter the annular gasket ring 7 through the air inlets. As the distance between the rear annular sealing plate 103 and the annular partition 3 continuously decreases, the air pressure inside the annular gasket ring 7 will continuously increase, and then the annular gasket ring 7 will be tightly pressed against the rear annular sealing plate 103 and the inner cryogenic tube 2 under the action of air pressure. This allows for a tighter seal between the interconnected inner cryogenic pipes 2, effectively improving the sealing performance between multiple interconnected double-wall cryogenic pipes, avoiding the risk of accidents caused by liquefied natural gas leaks, and effectively improving the safety of liquefied natural gas transportation.

[0036] A first conductive plate 302 is fixedly installed on the annular partition 3 near the rear annular sealing plate 103. The first conductive plate 302 is electrically connected to an external controller. A second conductive plate 1031, matching the first conductive plate 302, is fixedly installed on the rear annular sealing plate 103. A first solenoid valve is installed inside the first gas supply pipe 801, and the second conductive plate 1031 is electrically connected to the first solenoid valve. When inert gas is introduced into the insulation cavity, causing the annular partition 3 to move, when the annular partition 3 near the rear annular sealing plate 103 comes into contact with the rear annular sealing plate 103, the first conductive plate 302 will come into contact with the second conductive plate 1031. Then, the circuit between the external controller and the first solenoid valve will be connected, and the external controller can then control the first solenoid valve to close, thereby automatically controlling the first solenoid valve to close and stopping the supply of inert gas into the insulation cavity, effectively improving the automation of the double-walled cryogenic pipe.

[0037] A protective rubber nozzle 3031 is fixedly connected to the end of the abutment rod 303 that abuts against the inner cryogenic pipe 2. By setting the protective rubber nozzle 3031 at the end of the abutment rod 303 that abuts against the inner cryogenic pipe 2, when the annular baffle 3 removes the inner cryogenic pipe 2 from the outer insulation pipe 1 for maintenance via the abutment rod 303, it can avoid scratching the inner cryogenic pipe 2, thereby affecting the subsequent cooling effect of the inner cryogenic pipe 2 on liquefied natural gas.

[0038] The front annular sealing plate 102, the rear annular sealing plate 103, and the annular partition 3 are all coated with a heat-insulating coating. This coating prevents the temperature inside the inner cryogenic pipe 2 from being transferred out through the front annular sealing plate 102, the rear annular sealing plate 103, and the annular partition 3, thus affecting the cryogenic transport of liquefied natural gas. This effectively ensures that the liquefied natural gas can be transported at the specified temperature, preventing the vaporization of the liquefied natural gas.

[0039] Example 3: Reference Figures 1-9 A cooling and drying device is used for a double-walled LNG cryogenic pipe. More specifically, it includes a heat exchange tube 803 installed on the inner wall of an inner cryogenic pipe 2. An annular storage tank 8 is fixedly installed on the outer wall of an outer insulation pipe 1. The annular storage tank 8 and the heat exchange tube 803 are connected via a second gas supply pipe 802. A second solenoid valve is installed in the second gas supply pipe 802. When the temperature inside the inner cryogenic pipe 2 rises and cooling is required, the second solenoid valve in the second gas supply pipe 802 can be opened. Because the liquid helium pressure in the annular storage tank 8 is higher than the pressure in the heat exchange tube 803, the liquid helium will vaporize and absorb heat as it flows into the lower-pressure heat exchange tube 803. The helium flowing in the heat exchange tube 803 then cools the inner cryogenic pipe 2, thus ensuring that the liquefied natural gas remains at a low temperature and in a liquefied state, effectively improving the stability of liquefied natural gas transportation.

[0040] The heat exchange tube 803 is spirally coiled on the inner wall of the inner cryogenic tube 2. By making the heat exchange tube 803 spirally coiled on the inner wall of the inner cryogenic tube 2, when hydraulic natural gas is transported through the inner cryogenic tube 2, helium can be used to cool the inner cryogenic tube 2, ensuring that the hydraulic natural gas is always kept within the specified temperature range, avoiding vaporization problems, and further improving the stability of liquefied natural gas transportation.

[0041] An annular drying plate 104 is fixedly connected to the side of the connecting flange 101 away from the outer insulation pipe 1. The annular drying plate 104 is sleeved on the outside of the annular airbag ring 7. Annular drying plates 104 are installed on both sides of the outer insulation pipe 1. The annular drying plate 104 is made of diatomaceous earth. Since diatomaceous earth absorbs moisture quickly and dries quickly, it can quickly dry the annular airbag ring 7. When multiple double-walled cryogenic pipes are assembled, it can limit the position of the annular airbag ring 7, thereby improving the sealing effect of the annular airbag ring 7 on the gap between the two inner cryogenic pipes 2. Meanwhile, since the annular gasbag ring 7 lacks insulation material, frost will form on the outer wall of the annular gasbag ring 7 when hydraulic natural gas passes through this area. The annular drying plate 104 can dry the annular gasbag ring 7, preventing the frost on the outer wall of the annular gasbag ring 7 from turning into water and then freezing again, thus affecting the service life of the annular gasbag ring 7 and effectively ensuring the sealing effect of the annular gasbag ring 7 at the interface of each pair of inner cryogenic pipes 2.

[0042] Example 4: Reference Figures 1-9 A cooling and drying device is used for a double-walled LNG cryogenic pipe. More specifically, the end of a heat exchange tube 803 furthest from the second gas supply pipe 802 passes through the inner cryogenic pipe 2 and is connected to an insulated cavity. A recovery pipe 804 is fixedly connected to the insulated cavity near the second gas supply pipe 802. The recovery pipe 804 is connected to an annular storage tank 8, and a second one-way valve is installed inside the recovery pipe 804. A refrigeration compressor 805 is installed inside the annular storage tank 8. After the helium gas transported in the heat exchange tube 803 cools the cryogenic pipe 2, it is then transported into the insulated cavity through the outlet of the heat exchange tube 803. This facilitates the replenishment of helium into the insulated cavity, preventing helium loss due to prolonged storage and thus ensuring the insulation effect on the liquefied natural gas in the inner cryogenic pipe 2. This effectively guarantees that the insulated cavity is always filled with helium. When there is a large amount of helium in the insulation cavity and the pressure is greater than that of the second one-way valve, the excess helium will flow back into the annular storage tank 8 through the recovery pipe 804. Then, the helium can be repressurized and cooled into a liquid state by the refrigeration compressor 805. This allows for stable heat exchange and cooling of the transported liquefied natural gas to keep it in a liquid state, effectively ensuring the stable transport of hydraulic natural gas.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention.

Claims

1. A double-walled LNG cryogenic pipe, characterized in that, The double-wall LNG cryogenic pipe comprises an outer thermal insulation pipe and an inner cryogenic pipe, the outer thermal insulation pipe is sleeved on the inner cryogenic pipe, and the double-wall LNG cryogenic pipe further comprises: a connecting flange symmetrically fixedly installed at the opening of the outer thermal insulation pipe; a front annular sealing plate and a rear annular sealing plate symmetrically fixedly installed at the openings of the outer thermal insulation pipe; a plurality of annular partition plates slidably arranged in a thermal insulation cavity formed by the outer thermal insulation pipe, the front annular sealing plate, the rear annular sealing plate and the inner cryogenic pipe; a connecting rope fixedly connected between every two annular partition plates and between the front annular sealing plate and the adjacent annular partition plate; two air holes symmetrically formed in the annular partition plate away from the rear annular sealing plate, and a first one-way valve installed in each air hole and having a reverse flow direction; a stopper symmetrically connected to the annular partition plate near the front annular sealing plate by a torsional spring, and an inclined slot formed in the front annular sealing plate and the annular partition plate and matched with the stopper; a pulling assembly for pulling the plurality of annular partition plates to move towards the front annular sealing plate, and the pulling assembly is installed on the outer thermal insulation pipe; a first gas pipe installed on the outer thermal insulation pipe near the front annular sealing plate and connected with the thermal insulation cavity.

2. A double-walled LNG cryogenic pipe according to claim 1, characterized in that The pulling assembly comprises a pulling rope and a winding disc set, the winding disc set is symmetrically installed on the outer thermal insulation pipe near the front annular sealing plate, one end of the pulling rope is fixedly connected with a winding disc of the winding disc set, the other end of the pulling rope away from the winding disc set and extending into the thermal insulation cavity is fixedly connected with the annular partition plate near the rear annular sealing plate, the pulling rope sequentially penetrates through the plurality of annular partition plates away from the rear annular sealing plate, and a central shaft of the winding disc set is connected with an output end of an external driving part through a ratchet wheel.

3. A double-walled LNG cryogenic pipe according to claim 2, characterized in that The inner wall of the outer thermal insulation pipe near the front annular sealing plate is symmetrically provided with a protection roller, and the two pulling ropes are respectively wound on the adjacent protection rollers.

4. A double-walled LNG cryogenic pipe according to claim 1, characterized in that The rear annular sealing plate away from the annular partition plate is fixedly connected with an annular air bag ring, the annular air bag ring is sleeved on the inner cryogenic pipe, and the rear annular sealing plate and the annular air bag ring are respectively provided with a gas inlet hole penetrating each other.

5. A double-walled LNG cryogenic pipe according to claim 1, characterized in that, A first conductive sheet is fixedly installed on the annular partition plate near the rear annular sealing plate, a second conductive sheet matched with the first conductive sheet is fixedly installed on the rear annular sealing plate, a first electromagnetic valve is installed in the first gas pipe, and the second conductive sheet is electrically connected with the first electromagnetic valve.

6. A double-walled LNG cryogenic pipe according to claim 1, characterized in that, The end of the stopper abutting against the inner cryogenic pipe is fixedly connected with a protection rubber head.

7. A double-walled LNG cryogenic pipe according to claim 1, characterized in that, The front annular sealing plate, the rear annular sealing plate and the annular partition plate are all coated with a thermal insulation coating.

8. A cooling and drying device for a double-walled LNG cryogenic pipe according to claim 4, characterized in that, The double-wall LNG cryogenic pipe further comprises a heat exchange pipe installed on the inner wall of the inner cryogenic pipe, an annular storage box fixedly installed on the outer wall of the outer thermal insulation pipe, and a second gas pipe connected between the annular storage box and the heat exchange pipe, and a second electromagnetic valve is installed in the second gas pipe.

9. A cooling drying apparatus according to claim 8, wherein The heat exchange pipe is threadedly wound on the inner wall of the inner cryogenic pipe.

10. A cooling drying apparatus according to claim 8, wherein The connecting flange away from the outer thermal insulation pipe is fixedly connected with an annular drying plate, and the annular drying plate is sleeved on the outer side of the annular air bag ring.

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