Liquefied gas transport containers

Abstract

To suppress the occurrence of gas accumulation in a cooling pipe of a thermal shield in a liquefied gas transport container.SOLUTION: The liquefied gas transport container comprises an inner tank, a refrigerant tank, a thermal shield having a shield plate encircling the inner tank and a cooling pipe unit which is arranged on the surface of the shield plate and in which refrigerant cooling the shield plate flows, and an outer tank housing the inner tank and the thermal shield. The cooling pipe unit has: a plurality of cooling pipes formed in such a manner that the plurality of cooling pipes extending along the profile of the cross section of the shield plate in the vertical direction are axially arranged side by side; a refrigerant liquid supply pipe to which the lower ends of the plurality of cooling pipes are connected and which extends in the axial direction; and a refrigerant gas delivery pipe to which the upper ends of the plurality of cooling pipes are connected and which extends in the axial direction. The refrigerant liquid supply pipe has a communication port communicated with the refrigerant tank, and supplied with liquid-phase refrigerant from the refrigerant tank through the communication port, the refrigerant gas delivery pipe has a release port releasing gas-phase refrigerant to the outside.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a liquefied gas transport container used when transporting liquefied gas.

Background Art

[0002] When transporting liquefied gas, a liquefied gas transport container having a heat insulation function is used. The liquefied gas transport container includes an inner tank in which liquefied gas is stored, and an outer tank surrounding the inner tank. A heat shield covering the inner tank is disposed between the inner tank and the outer tank. The heat shield is cooled by an extremely low temperature liquid such as liquid nitrogen. Patent Document 1 discloses this type of liquefied gas transport container.

[0003] The transport container of Patent Document 1 includes an inner container that stores helium, a refrigerant container that stores a refrigerant that is an extremely low temperature liquid, an outer container that stores the inner container and the refrigerant container, a heat shield disposed between the outer container and the inner container, and a heat insulation element disposed between the heat shield and the outer container. The heat shield has a first cooling line through which the liquid-phase refrigerant flows, and the heat insulation element has a second cooling line through which the gas-phase refrigerant flows. The first cooling line includes two vertical portions extending in the gravitational direction and two inclined portions connecting the vertical portions, and a flow path from a distributor that supplies the refrigerant from the refrigerant container to the manifold via the vertical portion and the inclined portion in order, and a flow path from the inclined portion and the vertical portion to the manifold in order are formed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the cooling line for transport containers described in Patent Document 1, the inclined portion has a slight slope relative to the horizontal line, allowing bubbles generated in the inclined portion to rise downstream. However, the inclined portion extends in the longitudinal direction of the transport container, and as bubbles move along this long inclined portion, there is a risk that the bubbles may stagnate due to the tilt of the vehicle carrying the transport container while it is in motion.

[0006] This disclosure is made in view of the above circumstances, and its purpose is to propose a liquefied gas transport container comprising an inner tank, a heat shield, and an outer tank covering the inner tank and the heat shield, wherein the heat shield is cooled by a refrigerant flowing through a cooling pipe, and the generation of gas accumulation in the cooling pipe can be suppressed. [Means for solving the problem]

[0007] To solve the above problems, a liquefied gas transport container according to one aspect of this disclosure is: An inner tank containing liquefied gas, A refrigerant tank for storing refrigerant, A heat shield comprising a shield plate having a cylindrical body portion extending in a substantially horizontal axial direction that surrounds the inner tank, and a cooling pipe unit arranged on the surface of the shield plate through which the refrigerant that cools the shield plate flows, The system comprises the inner tank and the outer tank that houses the heat shield, The aforementioned cooling tube unit is The plurality of cooling tubes are arranged at intervals in the axial direction, each cooling tube extending vertically along the profile of the cross-sectional surface of the shield plate; the lower ends of the plurality of cooling tubes are connected to a refrigerant liquid supply tube that extends in the axial direction; and the upper ends of the plurality of cooling tubes are connected to a refrigerant gas discharge tube that extends in the axial direction. The refrigerant liquid supply pipe has a communication port that communicates with the refrigerant tank and receives the liquid phase of the refrigerant from the refrigerant tank through the communication port, and the refrigerant gas discharge pipe has an outlet that discharges the gaseous phase of the refrigerant to the outside. [Effects of the Invention]

[0008] According to one aspect of the present disclosure described above, in a liquefied gas transport container comprising an inner tank, a heat shield, and an outer tank covering the inner tank and the heat shield, the heat shield is cooled by a refrigerant flowing through a cooling pipe, and the occurrence of gas accumulation in the cooling pipe can be suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a diagram showing a schematic configuration of a liquefied gas transport container according to one embodiment of the present disclosure. [Figure 2] Figure 2 shows the configuration of the inner tank and heat shield. [Figure 3] Figure 3 is a cross-sectional view approximately perpendicular to the axial direction of the inner tank and heat shield. [Figure 4] Figure 4 shows the configuration of the inner tank and heat shield. [Figure 5] Figure 5 is a cross-sectional view showing the area near the flow path restriction of the exhaust pipe of the heat shield. [Figure 6] Figure 6 illustrates the internal tank and heat shield when the liquefied gas transport container is tilted in the axial direction. [Modes for carrying out the invention]

[0010] The liquefied gas transport container 1 according to this disclosure will be described below with reference to the drawings. Figure 1 is a diagram showing the schematic configuration of a liquefied gas transport container 1 according to one embodiment of this disclosure, and in this figure the inside of the outer tank 22 is shown as transparent. The liquefied gas transport container 1 shown in Figure 1 is also called a container and is used when transporting liquefied gas by ship and vehicle. Liquefied gas is a liquid at extremely low temperatures, such as liquefied helium, liquefied hydrogen, and liquefied natural gas. The configuration of the liquefied gas transport container 1 will be described below.

[0011] [Outline configuration of liquefied gas transport container 1] The liquefied gas transport container 1 comprises a tank body 11. The tank body 11 has a substantially horizontal central axis C, and the direction of extension of this central axis C is referred to as the "axial direction X". The tank body 11 has a cylindrical shape with the central axis C as its axis, and the longitudinal direction of the tank body 11 is substantially parallel to the axial direction X. The tank body 11 is mounted on a ship or vehicle, for example, while being supported by a frame 12. The frame 12 has support parts located at both ends of the tank body 11 in the axial direction X. By supporting both ends of the tank body 11 in the longitudinal direction with respect to the frame 12, the tank body 11 is held so as not to move relative to the frame 12.

[0012] The liquefied gas transport container 1 is configured to keep the stored liquefied gas at an extremely low temperature in order to suppress vaporization of the liquefied gas during transport. The tank body 11 comprises an inner tank 21, an outer tank 22, a heat shield 24, and a refrigerant tank 46.

[0013] The inner tank 21 is made of a metal such as SUS and has a cylindrical body with a central axis C as its axis, and end plates that close both ends of the body. Liquefied gas is stored in the inner tank 21 in a sealed state. The outer tank 22 covers the entire perimeter of the inner tank 21. The outer tank 22 is made of a metal such as SUS and has a cylindrical body with a central axis C as its axis, and end plates that close both ends of the body. The outer tank 22 is larger than the inner tank 21 in order to house the inner tank 21 inside it, and the outer wall of the inner tank 21 and the inner wall of the outer tank 22 are spaced apart.

[0014] The inner tank 21 is supported by the outer tank 22 via a support 30. The support 30 is a tubular, axial, or block-shaped member extending in the axial direction X, and positioned to overlap with the central axis C. The support 30 has a first connecting portion 31 connected to the inner tank 21 and a second connecting portion 32 connected to the outer tank 22. A portion of the support 30 may penetrate the wall of the inner tank 21 and be positioned inside the inner tank 21.

[0015] Both end portions of the inner tank 21 in the axial direction X are supported by the outer tank 22 via a plurality of suspension rods 33. The base end portion of each suspension rod 33 is coupled to the longitudinal end portion of the inner tank 21, and the tip end portion of each suspension rod 33 is coupled to the outer tank 22. The plurality of suspension rods 33 are arranged to extend radially about the central axis C. Thus, by the support body 30 and the plurality of suspension rods 33, the inner tank 21 is supported by the outer tank 22 inside the outer tank 22 in a state separated from the inner wall of the outer tank 22, in other words, in a floating state inside the outer tank 22.

[0016] A hollow inter-tank 25 is formed between the inner tank 21 and the outer tank 22. The inter-tank 25 may be in a vacuum state in order to suppress convective heat transfer. Also, the inter-tank 25 may be filled with a heat insulating material.

[0017] A heat shield 24 is disposed in the inter-tank space between the inner tank 21 and the outer tank 22. The heat shield 24 absorbs a part of the radiant heat from the outer tank 22 and blocks the heat input to the inner tank 21. The heat shield 24 has a shield plate 23 that covers the inner tank 21 and a cooling pipe unit 35 in which a refrigerant 44 flows and is disposed on the surface of the shield plate 23. The refrigerant tank 46 is disposed between the end portion of the inner tank 21 in the axial direction X and the outer tank 22, and the support body 30 penetrates the refrigerant tank 46 in the axial direction X. The refrigerant 44 is stored in the refrigerant tank 46. The refrigerant 44 is, for example, a low-temperature liquid such as liquid nitrogen. The type of the refrigerant 44 may be selected according to the type of the liquefied gas stored in the inner tank 21. The refrigerant 4 supplied from the refrigerant tank 46 flows through the cooling pipe unit 35, and by the refrigerant 44 exchanging heat with the shield plate 23, the surface temperature of the shield plate 23 is maintained at an extremely low temperature. By covering the inner tank 21 with the shield plate 23 thus maintained at an extremely low temperature, the heat input to the inner tank 21 is suppressed.

[0018] 〔Configuration of Heat Shield 24〕 Here, the configuration of the heat shield 24 in the liquefied gas transport container 1 will be described in detail. FIG. 2 is a diagram showing the configuration of the inner tank 21 and the heat shield 24, and FIG. 3 is a cross-sectional view orthogonal to the axial direction X of the inner tank 21 and the heat shield 24.

[0019] As shown in Figures 2 and 3, the heat shield 24 comprises a shield plate 23 and a cooling tube unit 35 arranged along the surface of the shield plate 23. The shield plate 23 is made of a metal panel material such as aluminum and has a cylindrical shape extending in the axial direction X with a central axis C as its axis.

[0020] The cooling tube unit 35 has a plurality of cooling tubes 41 arranged along the surface of the shield plate 23. More specifically, the cooling tube unit 35 has a refrigerant liquid supply pipe 40, a refrigerant gas discharge pipe 42, and a plurality of cooling tubes 41. The number of cooling tubes 41 is not particularly limited and depends on the size of the shield plate 23 and the degree of cooling of the shield plate 23. Each of the plurality of cooling tubes 41 has an arc shape that extends vertically along the profile of the cross-section of the shield plate 23. Here, "extending vertically" means that the cooling tube 41 has a lower end and an upper end, and that the lower end and upper end are separated in the vertical direction, and is not limited to the cooling tube 41 extending in a straight line vertically. The cooling tube 41 extends continuously upward from the lower end to the upper end and does not bend in a U-shape or L-shape or turn downward along the way. The axial X position of the lower end and upper end of the cooling tube 41 is substantially the same. However, the axial positions X of the lower and upper ends of the cooling tube 41 may be slightly separated.

[0021] Multiple cooling pipes 41 are arranged at intervals in the axial direction X. The lower ends of the multiple cooling pipes 41 are connected to a refrigerant liquid supply pipe 40. The refrigerant liquid supply pipe 40 is a pipe that extends in the axial direction X at the lower part of the shield plate 23 and has a larger pipe diameter than the cooling pipes 41. The refrigerant liquid supply pipe 40 is a "header pipe" that bundles the multiple cooling pipes 41 and distributes refrigerant 44 to each cooling pipe 41. The refrigerant liquid supply pipe 40 has a communication port 45 that communicates with a refrigerant tank 46. Refrigerant 44 flows from the refrigerant tank 46 to the refrigerant liquid supply pipe 40 through this communication port 45.

[0022] The upper ends of the multiple cooling pipes 41 are connected to a refrigerant gas discharge pipe 42. The refrigerant gas discharge pipe 42 is a pipe that extends axially X in the upper part of the shield plate 23 and has a larger diameter than the cooling pipes 41. The refrigerant gas discharge pipe 42 is a "header pipe" that bundles the multiple cooling pipes 41 and collects refrigerant 44 from the multiple cooling pipes 41. The refrigerant gas discharge pipe 42 has an outlet 48 at its downstream end. An exhaust pipe 43 is connected to the outlet 48, and the refrigerant 44 in the refrigerant gas discharge pipe 42 is exhausted to the outside through the exhaust pipe 43 from the outlet 48. A flow restriction 63 is provided in the exhaust pipe 43. Normally, gaseous refrigerant 44 flows into the exhaust pipe 43 from the refrigerant gas discharge pipe 42, but if there is a possibility that liquid refrigerant 44 will flow into the exhaust pipe 43, a gas-liquid separator 64 may be provided upstream of the flow restriction 63. The gas-liquid separator 64 removes the liquid phase refrigerant 44 from the refrigerant 44 flowing into the exhaust pipe 43 and allows the gaseous phase refrigerant to pass through. For example, it may be a gas-liquid separation valve.

[0023] The refrigerant liquid supply pipe 40 and the refrigerant gas discharge pipe 42 are spaced apart vertically, with multiple cooling pipes 41 in between. It is desirable that the refrigerant gas discharge pipe 42 be positioned above the maximum liquid level height specified for the inner tank 21. Note that the maximum liquid level height is a design value given to the inner tank 21, and it is not permitted to contain liquefied gas in the inner tank 21 at a level exceeding the maximum liquid level height.

[0024] The length of each cooling tube 41 is, in principle, less than half the circumference of the cylindrical shield plate 23. The cooling tube units 35 in the above configuration are arranged on both sides of the shield plate 23 via the central axis C. In this case, the cooling tube units 35 may be arranged on both sides of the shield plate 23 so as to be symmetrical with respect to a vertical plane passing through the central axis C.

[0025] In the cooling pipe unit 35, the refrigerant liquid supply pipe 40 is connected to the refrigerant tank 46, and liquid-phase refrigerant 44 is supplied from the refrigerant tank 46 to the refrigerant liquid supply pipe 40. Liquid-phase refrigerant 44 has higher cooling efficiency than gaseous refrigerant 44. Therefore, it is desirable that the liquid level of refrigerant 44 in the cooling pipe unit 35 be within the vertical height of the cooling pipes 41 and closer to the upper end of the cooling pipes 41 (see Figure 2), or within the vertical height of the refrigerant gas discharge pipe 42 and at a position where a gas layer is formed above the refrigerant gas discharge pipe 42 (see Figure 4). Accordingly, a flow restriction (orifice) 63 is positioned downstream of the connection point of the multiple cooling pipes 41 in the refrigerant gas discharge pipe 42, and the pressure in the refrigerant tank 46 is adjusted by a pressure control device 47 connected to the refrigerant tank 46, thereby controlling the liquid level of refrigerant 44 in the cooling pipe unit 35 to a predetermined set liquid level. Here, the "set liquid level" is pre-set in the pressure control device 47. The set liquid level height may be any height within the vertical range of the multiple cooling pipes 41 or within the vertical range of the refrigerant gas discharge pipe 42.

[0026] Figure 5 is a cross-sectional view showing the vicinity of the flow path restriction 63 in the exhaust pipe 43 of the heat shield 24. As shown in Figure 5, a throttling member 38 is positioned inside the exhaust pipe 43 to close the flow path cross-section. The throttling member 38 has a through hole 38a that penetrates the throttling member 38 in the flow path direction. This through hole 38a has a smaller flow path cross-sectional area compared to other parts of the exhaust pipe 43 and functions as a flow path restriction 63. The flow path restriction 63 positioned in the exhaust pipe 43 increases the flow resistance of the exhaust pipe 43 compared to the refrigerant gas discharge pipe 42. As a result, the discharge of refrigerant 44 through the exhaust pipe 43 is restricted, the consumption rate of refrigerant 44 is suppressed, and the pressure inside the cooling pipe unit 35 can be controlled as described above. Furthermore, vaporization of refrigerant 44 upstream of the flow path restriction 63 (or the flow path restriction 63 and gas-liquid separator 64) can be promoted. The diameter d of the flow path restriction 63 should be set appropriately so as to prevent the passage of liquid-phase refrigerant 44, while allowing the passage of an appropriate amount of gas-phase refrigerant 44 so as to maintain proper cooling of the shield plate 23.

[0027] When the pressure at the top of the refrigerant tank 46 (i.e., the gas phase) is defined as the upper pressure P1 and the pressure at the bottom of the refrigerant tank 46 (i.e., the liquid phase) is defined as the bottom pressure P2, the bottom pressure P2 is the upper pressure P1 plus the head pressure (hydrostatic pressure) of the liquid-phase refrigerant 44 stored in the refrigerant tank 46. As the liquid-phase refrigerant 44 in the refrigerant tank 46 decreases moment by moment as it flows out into the cooling pipe unit 35, the head pressure of the refrigerant 44 in the refrigerant tank 46 changes. Therefore, the pressure management device 47 controls the upper pressure P1 so that the bottom pressure P2 becomes a predetermined set pressure corresponding to the set liquid level height of the aforementioned cooling pipe unit 35. This allows the liquid level of the refrigerant 44 in the cooling pipe 41 to be maintained at the set liquid level height. The set pressure corresponding to the set liquid level height differs for each liquefied gas transport container 1 and can be determined by simulation or experiment.

[0028] Returning to Figure 2, the pressure control device 47 has a back pressure valve 471 connected to the gas phase portion of the refrigerant tank 46. The back pressure valve 471 opens when the bottom pressure P2 exceeds the predetermined set pressure mentioned above, allowing the refrigerant 44 in the gas phase of the refrigerant tank 46 to escape to the outside, and closes when the bottom pressure P2 is below the predetermined set pressure mentioned above. The opening of the back pressure valve 471 reduces the upper pressure P1 of the refrigerant tank 46, and as a result, the bottom pressure P2 decreases. It is desirable that the back pressure valve 471 is constructed without using any electrical components that could be an ignition source. A pressure control device 47 equipped with such a back pressure valve 471 can be realized, for example, by applying the technology disclosed in Japanese Patent No. 6009929. However, the structure of the pressure control device 47 is not limited thereto.

[0029] The pressure control device 47 maintains a constant bottom pressure P2 in the refrigerant tank 46, thereby supplying refrigerant 44 from the refrigerant tank 46 to the refrigerant liquid supply pipe 40 to compensate for any drop in the liquid level. In other words, by adjusting the pressure in the refrigerant tank 46, the liquid level of the refrigerant 44 in the cooling pipe unit 35 is maintained at the set liquid level. As a result, the pressure conditions of the refrigerant 44 in the cooling pipe 41 are kept approximately constant, the shield plate 23 continues to be cooled effectively, and heat input to the inner tank 21 is suppressed.

[0030] [Summary] As described above, the liquefied gas transport container 1 according to one aspect of this disclosure is An inner tank 21 containing liquefied gas, A refrigerant tank 46 for storing refrigerant 44, A heat shield 24 having a shield plate 23 having a cylindrical body portion that extends in a substantially horizontal axial direction X surrounding the inner tank 21, and a cooling pipe unit 35 arranged on the surface of the shield plate 23 through which a refrigerant 44 that cools the shield plate 23 flows, It comprises an inner tank 21 and an outer tank 22 that houses a heat shield 24. The cooling tube unit 35 comprises a plurality of cooling tubes 41 arranged at intervals in the axial direction X, each cooling tube 41 extending vertically along the profile of the cross-sectional surface of the shield plate 23, a refrigerant liquid supply pipe 40 to which the lower ends of the plurality of cooling tubes 41 are connected and which extends in the axial direction X, and a refrigerant gas discharge pipe 42 to which the upper ends of the plurality of cooling tubes 41 are connected and which extends in the axial direction X. The refrigerant liquid supply pipe 40 has a communication port 45 that communicates with the refrigerant tank 46 and receives liquid phase refrigerant 44 from the refrigerant tank 46 through the communication port 45, and the refrigerant gas discharge pipe 42 has an outlet 48 that discharges gas phase refrigerant 44 to the outside.

[0031] In the liquefied gas transport container 1 with the above configuration, the refrigerant liquid supply pipe 40 is filled with liquid-phase refrigerant 44, and the multiple cooling pipes 41 contain both liquid-phase refrigerant 44 that flows in from the refrigerant liquid supply pipe 40 and gaseous refrigerant 44 that has been heated and vaporized by heat exchange with the shield plate 23. Since the refrigerant 44 in the refrigerant liquid supply pipe 40 is in single-phase flow, it flows without stagnation due to pressure. Although bubbles are generated in the cooling pipes 41, since the cooling pipes 41 extend vertically, the bubbles generated in the cooling pipes 41 quickly rise and flow into the refrigerant gas discharge pipe 42. In this way, the occurrence of gas accumulation in the cooling pipes 41 is suppressed. Therefore, the occurrence of problems such as uneven cooling of the shield plate 23 and stagnation of the flow of refrigerant 44 in the cooling pipes 41, which are caused by gas accumulation in the cooling pipes 41, is suppressed.

[0032] In the liquefied gas transport container 1 with the above configuration, the inner tank 21 has a specified maximum liquid level, and the refrigerant gas discharge pipe 42 of the cooling pipe unit 35 may be positioned above the maximum liquid level of the inner tank 21.

[0033] The fact that the refrigerant gas discharge pipe 42 is positioned above the highest liquid level of the inner tank 21 means that the upper end of the cooling pipe 41 is positioned at or above the highest liquid level of the inner tank 21. Therefore, the liquefied gas in the liquid phase of the inner tank 21 falls within the range cooled by the cooling pipe 41 and can be sufficiently cooled.

[0034] In the liquefied gas transport container 1 with the above configuration, the cooling pipe unit 35 has an exhaust pipe 43 connected to the portion of the refrigerant gas discharge pipe 42 downstream of the connection point with the plurality of cooling pipes 41, and a flow path restrictor 63 located in the exhaust pipe 43. The refrigerant tank 46 may have a pressure control device 47 that adjusts the pressure inside the refrigerant tank 46 so that the liquid level of the refrigerant 44 in the cooling pipe unit 35 reaches a predetermined set liquid level. Here, the set liquid level may be within the vertical range of the plurality of cooling pipes 41 or within the vertical range of the refrigerant gas discharge pipe 42. The cooling pipe unit 35 may also have a gas-liquid separator 64 located upstream of the flow path restrictor 63 in the exhaust pipe 43.

[0035] As shown in Figure 2, the liquid level of the refrigerant 44 in the cooling tube unit 35 is maintained within the vertical range of the multiple cooling tubes 41, thereby forming a continuous gas layer in the axial direction X across the entire refrigerant gas discharge pipe 42. In this case, even if the liquefied gas transport container 1 is tilted slightly in the axial direction X, the liquid level of the refrigerant 44 in the cooling tube unit 35 is maintained within the vertical range of the multiple cooling tubes 41, and the continuous gas layer in the axial direction X across the refrigerant gas discharge pipe 42 is maintained, preventing gas buildup in the cooling tubes 41.

[0036] Furthermore, as shown in Figure 4, by maintaining the liquid level of the refrigerant 44 in the cooling pipe unit 35 within the upper and lower range of the refrigerant gas discharge pipe 42, a gas layer continuous in the axial direction X is formed above the refrigerant gas discharge pipe 42. In this gas layer of the refrigerant gas discharge pipe 42, the gaseous refrigerant 44 flows smoothly to the outlet 48. Here, for example, as shown in Figure 6, if the liquefied gas transport container 1 is temporarily tilted significantly in the axial direction X, the liquid phase refrigerant 44 in the refrigerant gas discharge pipe 42 may temporarily block the refrigerant gas discharge pipe 42, causing a temporary gas accumulation in the cooling pipe 41. However, once the liquefied gas transport container 1 returns to a steady position (i.e., the position where the axial direction X is approximately horizontal as shown in Figure 4), the liquid phase refrigerant 44 in the refrigerant gas discharge pipe 42 flows down into the cooling pipe 41, restoring the gas layer continuous in the axial direction X above the refrigerant gas discharge pipe 42, and the gas accumulation is automatically resolved.

[0037] The discussions of this disclosure described above are presented for illustrative and explanatory purposes only and are not intended to limit the disclosure to the forms disclosed herein. For example, in the detailed description above, various features of the disclosure are grouped into a single embodiment for the purpose of streamlining the disclosure. However, some of the features contained herein can be combined into alternative embodiments, configurations, or aspects other than those discussed above. [Explanation of Symbols]

[0038] 1: Liquefied gas transport container 21: Inner tank 22: Outer tank 23: Shielding plate 24: Heat Shield 35: Cooling pipe unit 40: Refrigerant liquid supply pipe 41: Cooling pipe 42: Refrigerant gas discharge pipe 43: Exhaust pipe 44: Refrigerant 45: Connecting port 48: Exhaust vent 46: Refrigerant tank 47: Pressure control device 63: Flow channel restriction 64: Gas-liquid separator X: Axis direction

Claims

1. An inner tank containing liquefied gas, A refrigerant tank for storing refrigerant, A heat shield comprising a shield plate having a cylindrical body extending in the horizontal axial direction that surrounds the inner tank, and a cooling pipe unit arranged on the surface of the shield plate through which the refrigerant that cools the shield plate flows, The system comprises the inner tank and the outer tank that houses the heat shield, The aforementioned cooling tube unit is The plurality of cooling tubes are arranged at intervals in the axial direction, each cooling tube extending vertically along the profile of the cross-sectional surface of the shield plate; the lower ends of the plurality of cooling tubes are connected to a refrigerant liquid supply tube that extends in the axial direction; and the upper ends of the plurality of cooling tubes are connected to a refrigerant gas discharge tube that extends in the axial direction. The refrigerant liquid supply pipe has a communication port that communicates with the refrigerant tank and receives the liquid phase of the refrigerant from the refrigerant tank through the communication port, and the refrigerant gas discharge pipe has an outlet that discharges the gas phase of the refrigerant to the outside. Container for transporting liquefied gas.

2. The inner tank has a defined maximum liquid level height. The refrigerant gas discharge pipe of the cooling pipe unit is positioned above the highest liquid level of the inner tank. A liquefied gas transport container according to claim 1.

3. The cooling pipe unit includes an exhaust pipe connected to the portion of the refrigerant gas discharge pipe downstream of the connection point with the plurality of cooling pipes, and a flow restriction positioned in the exhaust pipe. The refrigerant tank has a pressure control device that adjusts the pressure inside the refrigerant tank so that the liquid level of the refrigerant in the cooling pipe unit reaches a predetermined set liquid level. The set liquid level is within the vertical range of the plurality of cooling pipes or within the vertical range of the refrigerant gas discharge pipe. A liquefied gas transport container according to claim 1 or 2.

4. The cooling pipe unit has a gas-liquid separator located upstream of the flow path restriction in the exhaust pipe. A liquefied gas transport container according to claim 3.

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