JP2018119634A - Heat insulation structure of liquefied gas storage tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat insulation structure that eliminates deterioration in heat insulation performance due to replacement of ambient air or nitrogen gas or the like with inert gas, has high heat insulation properties and can reduce an installation space.SOLUTION: A heat insulation structure of a liquefied gas storage tank according to several embodiments has a heat insulation layer covering a surface of an outer wall of the liquefied gas storage tank storing liquefied gas. The heat insulation layer includes a first layer of a heat insulator having independent air bubbles, and air non-permeable layers provided on both sides of the first layer, and at least one of the air non-permeable layers provided on both the sides of the first layer includes a vacuum heat insulator formed by covering and sealing a core material with a jacket material having gas barrier properties and reducing the pressure in the jacket material.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a heat insulating structure of a liquefied gas storage tank.

In a carrier ship such as LNG (liquefied natural gas), in order to minimize the generation rate of boil-off gas (BOG) in the LNG tank, it is necessary to cover the outer wall surface of the tank with a heat insulating material having low thermal conductivity. As a heat insulating material with low thermal conductivity, for example, there are heat insulating materials having closed cells such as polyurethane foam (PUF) and beaded polystyrene foam (EPS).
However, if it is attempted to reduce BOG with a single heat insulating material such as PUF, the thickness becomes unrealistic and the installation space may not be secured.
Therefore, Patent Document 1 discloses a heat insulating structure using a vacuum heat insulating material in order to realize high-performance heat insulation.

JP 2010-249174 A

An inert gas such as nitrogen gas may flow between the outer wall of the liquefied gas storage tank and the heat insulating material to absorb moisture in the air / prevent freezing and detect leakage of the liquefied gas.
The heat conductivity of PUF is about 0.02 W / mK at room temperature (20 ° C.), but by substituting the surrounding air or nitrogen gas with a gas with low thermal conductivity, such as alternative chlorofluorocarbon enclosed in closed cells. It is known that the heat insulation performance may deteriorate.

  In the heat insulating structure disclosed in Patent Document 1, a surface material (a laminate of an aluminum sheet and a plastic film) is applied to the outer side surface, so that there is no possibility that the gas in the closed cell is replaced with ambient air. However, when nitrogen gas flows inside, the vacuum heat insulating material has a structure built in a heat insulating material such as PUF, so that the gas in the closed cell may be replaced with nitrogen gas and the heat insulating performance may be deteriorated.

  An object of at least one embodiment is to propose a heat insulating structure that eliminates deterioration of heat insulating performance due to substitution with an inert gas such as ambient air or nitrogen gas, and has high heat insulating performance and can reduce installation space. To do.

(1) The heat insulation structure of the liquefied gas storage tank according to some embodiments is
A heat insulating structure for a liquefied gas storage tank having a heat insulating layer covering a surface of an outer wall of the liquefied gas storage tank for storing the liquefied gas,
The thermal insulation layer is
A first layer which is a heat insulating material having closed cells;
A non-breathable layer provided on both sides of the first layer;
Including
At least one of the non-breathing layers provided on both sides of the first layer includes a vacuum heat insulating material in which the core material is covered with a jacket material having a gas barrier property and sealed to reduce the pressure inside the jacket material.

According to the configuration of (1) above, by providing the non-breathing layer on both sides of the first layer, which is a heat insulating material having closed cells, gas having low thermal conductivity in the closed cells of the first layer can be obtained. Substitution with an inert gas such as ambient air or nitrogen gas can be suppressed, thereby preventing deterioration of the heat insulation performance of the first layer.
In addition, heat insulation performance can be improved by including a vacuum heat insulating material having excellent gas barrier properties and heat insulation performance in at least one of the non-breathing layers, thereby reducing the generation rate of BOG and reducing the installation space. .

(2) In one embodiment, in the configuration of (1),
The non-breathing layer includes an outer non-breathing layer provided outside the first layer,
The outer non-breathing layer includes the vacuum heat insulating material.
According to the configuration of (2) above, the outer non-breathing layer provided outside the first layer includes the vacuum heat insulating material having excellent gas barrier properties and heat insulating performance, thereby reducing the low heat in the closed cells of the first layer. It is possible to prevent the conductivity gas from being replaced with the ambient air outside the heat insulating layer. Moreover, the high heat insulating performance of the vacuum heat insulating material enables the heat insulating layer to be thinned, thereby reducing the installation space for the heat insulating layer.

(3) In one embodiment, in the configuration of (1),
The non-breathing layer includes an inner non-breathing layer provided inside the first layer,
The inner non-breathing layer includes the vacuum heat insulating material.
According to the configuration of (3) above, the inner non-venting layer provided on the inner side of the first layer includes the vacuum heat insulating material having excellent gas barrier properties and heat insulating performance, thereby reducing the low heat in the closed cells of the first layer. Replacement of the conductivity gas with an inert gas can be suppressed. Moreover, the high heat insulating performance of the vacuum heat insulating material enables the heat insulating layer to be thinned, thereby reducing the installation space for the heat insulating layer.

(4) In one embodiment, in the configuration of (3),
The thermal insulation layer is
It further includes a second layer which is a heat insulating material having closed cells provided inside the inner non-breathing layer.
According to the configuration of (4) above, when the minimum usable temperature of the vacuum heat insulating material is higher than the temperature of the liquefied gas, the second layer is disposed inside the inner non-venting layer including the vacuum heat insulating material, thereby The region where the non-air-permeable layer is disposed can be set to the minimum usable temperature or higher of the vacuum heat insulating material, thereby preventing the vacuum heat insulating material included in the inner non-air-permeable layer from being deteriorated.

(5) In one embodiment, in the configuration of (4),
The thermal insulation layer is
A non-breathable covering material provided on the inner side of the second layer is further included.
According to the configuration of (5) above, the presence of the non-breathable coating material provided on the inner side of the second layer can suppress the substitution of the gas in the closed cells of the second layer with the inert gas. Therefore, the deterioration of the heat insulation performance of the second layer can be suppressed by providing this non-breathable coating material.

(6) In one embodiment, in any one of the configurations (1) to (5),
The other of the non-breathing layers provided on both sides of the first layer includes the vacuum heat insulating material.
According to the configuration of (6) above, since the non-venting layer provided on both sides of the first layer includes the vacuum heat insulating material having excellent heat insulating performance and gas barrier properties, deterioration of the heat insulating performance of the first layer can be suppressed. At the same time, the heat insulation performance of the heat insulation layer can be further improved.

(7) In one embodiment, in any one of the configurations (1) to (5),
The other of the non-breathing layers provided on both sides of the first layer is a non-breathable coating material.
According to the configuration of (7) above, by using a non-breathable covering material as the non-breathable layer, it is possible to suppress deterioration of the heat insulation performance due to the replacement of the gas in the closed cells of the first layer. Moreover, the installation space of a heat insulation layer can be reduced by using a thin non-breathable covering material.

(8) In one embodiment, in any one of the configurations (1) to (7),
The non-breathable layer includes a plurality of non-breathable covering materials arranged so that the end portions overlap each other.

The heat insulating layer covering the surface of the outer wall of the liquefied gas storage tank is configured by laying a plurality of first layers and vacuum heat insulating materials, and a seam is formed between adjacent first layers and vacuum heat insulating materials. .
According to the configuration of the above (8), by arranging the end portions of the plurality of non-breathable covering materials so as to overlap each other, it is possible to seal these seams, whereby the first layer is surrounded by ambient air and nitrogen gas. Therefore, it is possible to suppress the deterioration of the heat insulation performance due to the replacement of the gas in the closed cells of the first layer.

(9) In one embodiment, in any one of the configurations (1) to (8),
The liquefied gas storage tank is provided in a liquefied gas carrier ship.
According to the configuration of (9) above, the liquefied gas storage tank eliminates deterioration of the heat insulation performance due to replacement with ambient air or nitrogen gas, and has a high heat insulation performance, and thus can be thinned. Thereby, since the installation space of a heat insulation layer can be reduced, the freedom degree of arrangement | positioning can be expanded also in the liquefied gas carrier ship with which the volume and ship width were limited. Moreover, since the weight increase of a heat insulation layer can be suppressed, the deterioration of the operation performance of a liquefied gas carrier ship can be suppressed.

  According to some embodiments, the heat insulation structure of the liquefied gas storage tank can be prevented from being deteriorated due to replacement with an inert gas such as ambient air or nitrogen gas, and thinned with high heat insulation performance. And the installation space can be reduced.

It is sectional drawing of the liquefied gas storage tank which concerns on one Embodiment provided in the liquefied gas carrier ship. It is sectional drawing of the heat insulation structure of the liquefied gas storage tank which concerns on one Embodiment. It is sectional drawing of the heat insulation structure of the liquefied gas storage tank which concerns on one Embodiment. It is sectional drawing of the heat insulation structure of the liquefied gas storage tank which concerns on one Embodiment. It is sectional drawing of the heat insulation structure of the liquefied gas storage tank which concerns on one Embodiment. It is sectional drawing of the heat insulation structure of the liquefied gas storage tank which concerns on one Embodiment. It is sectional drawing of the heat insulation structure of the liquefied gas storage tank which concerns on one Embodiment.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
In addition, for example, expressions representing shapes such as quadrangular shapes and cylindrical shapes not only represent shapes such as quadrangular shapes and cylindrical shapes in a strict geometric sense, but also within the range where the same effect can be obtained. A shape including a chamfered portion or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

The heat insulation structure of the liquefied gas storage tank according to some embodiments includes a heat insulating layer 20 formed so as to cover the outer wall surface of the liquefied gas storage tank 12, as shown in FIG.
As shown in FIGS. 2 to 7, the heat insulating layer 20 (20 </ b> A, 20 </ b> B, 20 </ b> C, 20 </ b> D, 20 </ b> E, 20 </ b> F) includes a first layer 24 and non-breathing layers 22 and 26 provided on both sides of the first layer 24. Including. The first layer 24 is a heat insulating material having closed cells b, and at least one of the non-air-permeable layers 22 and 26 includes a vacuum heat insulating material 32.
2 to 7 are enlarged cross-sectional views showing a portion A in FIG. 1. In FIGS. 2 to 7, o represents an atmosphere outside the heat insulating layer 20, and i represents the inside of the liquefied gas storage tank 12. A liquefied gas atmosphere is shown.

  The vacuum heat insulating material is obtained by using, for example, an inorganic heat insulating material as a core material, covering the core material with an outer shell material having excellent gas barrier properties, and sealing the inner surface of the outer jacket material. Typical core materials include, for example, foams such as urethane, powder materials such as silica, and fiber materials such as glass wool. As the jacket material, for example, an aluminum sheet, a multilayer laminate film, or the like is used. Since the inside of the jacket material is depressurized, no convection occurs, and the core material has a high heat transfer resistance due to its high porosity, thereby having high heat insulation performance.

In one embodiment, the liquefied gas is, for example, LNG, LPG (liquefied petroleum gas), or the like. Moreover, the 1st layer 24 is PUF, EPS, etc. which have the closed cell b, for example, and has high heat insulation performance by having the closed cell b.
In one embodiment, a gas having a low thermal conductivity, such as alternative chlorofluorocarbon, is enclosed in the closed cells b of the first layer 24. Heat insulation performance can be further improved by enclosing a gas having low thermal conductivity in the closed cell b.

In one embodiment, a gap s in which an inert gas such as nitrogen gas is supplied is formed between the outer wall 28 of the liquefied gas storage tank 12 and the heat insulating layer 20. By flowing an inert gas such as nitrogen gas through the gap s, moisture absorption / freezing of moisture in the air can be prevented, and by sampling the gas in the gap s, it is possible to detect the presence or absence of leakage of the liquefied gas.
In one embodiment, the liquefied gas storage tank 12 is mounted on a liquefied gas carrier 10 as shown in FIG.

According to the above configuration, by providing the non-breathing layers 22 and 26 on both sides of the first layer 24 which is a heat insulating material having closed cells, the gas having low thermal conductivity in the closed cells b of the first layer 24 can be obtained. Substitution with an inert gas such as ambient air or nitrogen gas can be suppressed, and thereby the deterioration of the heat insulation performance of the first layer 24 can be suppressed.
In addition, since at least one of the non-venting layers 22 and 26 includes the vacuum heat insulating material 32 having excellent gas barrier properties and heat insulating performance, the heat insulating performance can be improved, thereby reducing the generation rate of BOG and the heat insulating layer. 20 can be reduced in thickness, and the installation space can be reduced.
The heat conductivity of PUF is about 0.02 W / mK at room temperature (20 ° C), whereas the general heat conductivity of vacuum heat insulating materials is about 0.002 W / mK. Have.

In one embodiment, as shown in FIGS. 2 to 7, the outer non-venting layer 22 provided on the outer side of the first layer 24 includes a vacuum heat insulating material 32.
Thus, by having the vacuum heat insulating material having excellent gas barrier properties and heat insulating performance outside the first layer 24, the low thermal conductivity gas in the closed cells b of the first layer 24 is separated from the ambient air outside the heat insulating layer. Replacement can be suppressed, and the installation space for the heat insulating layer 20 can be reduced by the high heat insulating performance of the vacuum heat insulating material.

In one embodiment, the heat insulation layer 20 (20A, 20B, 20C, 20D, 20F) shown in FIG. 2 to FIG. 7 excluding FIG. 6 is an inner non-air-permeable layer 26 provided inside the first layer 24. 32.
Thus, by having the vacuum heat insulating material 32 having excellent gas barrier properties and heat insulating performance inside the first layer 24, the low thermal conductivity gas in the closed cell b of the first layer 24 is replaced with an inert gas or the like. The installation space of the heat insulation layer 20 can be reduced by the high heat insulation performance of the vacuum heat insulating material 32.

In one embodiment, the heat insulating layer 20 (20C, 20D) shown in FIGS. 4 and 5 further includes a second layer 30 that is provided inside the inner non-venting layer 26 and is a heat insulating material having closed cells.
In one embodiment, the 2nd layer 30 is PUF, EPS, etc. which have closed cell b like the 1st layer 24, for example, and has high heat insulation performance by having closed cell b. In addition, a gas having a low thermal conductivity such as an alternative chlorofluorocarbon is enclosed in the closed cell b, thereby further improving the heat insulation performance.

  When the minimum usable temperature of the vacuum heat insulating material 32 is higher than the temperature of the liquefied gas, the vacuum heat insulating material 32 is disposed by further disposing the second layer 30 inside the inner non-venting layer 26 including the vacuum heat insulating material 32. The region can be above the minimum usable temperature. Thereby, deterioration of the vacuum heat insulating material contained in the inner non-air-permeable layer 26 can be suppressed. Note that the presence of the inner non-breathing layer 26 including the vacuum heat insulating material 32 suppresses the gas replacement in the closed cells b of the first layer 24 and suppresses the deterioration of the heat insulating performance of the first layer 24. In this embodiment, deterioration of the heat insulation performance of the second layer 30 due to the inert gas is allowed.

In one embodiment, the heat insulating layer 20 (20 </ b> D) shown in FIG. 5 further includes a non-breathable covering material 34 provided inside the second layer 30.
In one embodiment, the non-breathable covering material 34 is a laminate of an aluminum sheet and a plastic film.
Due to the presence of the non-breathable covering material 34, in addition to the effect of obtaining the heat insulating layer 20 (20C) shown in FIG. 4, it is possible to suppress the gas in the closed cells of the second layer 30 from being replaced with an inert gas, Thereby, deterioration of the heat insulation performance of the second layer 30 can be suppressed.

In one embodiment, the heat insulating layer 20 (20A, 20B, 20C, 20D, 20F) shown in FIGS. 2 to 7 except for FIG. 6 is used for the non-breathing layers 22 and 26 provided on both sides of the first layer 24. Insulating material 32 is included.
As described above, since the vacuum heat insulating material 32 having excellent heat insulating performance and gas barrier property is arranged on both sides of the first layer 24, the gas having low thermal conductivity in the closed cell b of the first layer 24 and the outer periphery The replacement with air and an inert gas inside can be suppressed, the deterioration of the heat insulation performance of the first layer 24 can be suppressed, and the heat insulation performance of the heat insulation layer 20 can be further improved.

In one embodiment, the heat insulating layer 20 (20B, 20D, 20E) shown in FIGS. 3, 5, and 6 is provided with a vacuum heat insulating material 32 on at least one of the non-breathing layers 22, 26 outside and inside the first layer 24. And a non-breathable covering material 34 is provided on at least the other non-breathable layers 22 and 26.
Thus, by using the non-breathable coating material 34 having a small thickness for the non-breathing layer 22 or 26, it is possible to suppress the deterioration of the heat insulation performance due to the replacement of the gas in the closed cells of the first layer 24, and It is possible to reduce the installation space.

In one embodiment, the thermal insulation layer 20 (20B, 20D, 20E) shown in FIGS. 3, 5, and 6 has a non-breathable coating 34 on the outermost and innermost sides of the thermal insulation layer.
According to the above configuration, by using the non-breathable covering material 34 having a small thickness on both sides of the first layer 24, it is possible to prevent deterioration of the heat insulating performance due to the replacement of the gas in the closed cells of the first layer 24, and The heat insulation layer can be made thinner and the installation space can be further reduced.

In one embodiment, the thermal insulation layer 20 (20B, 20D, 20E) shown in FIGS. 3, 5 and 6 is such that at least one of the non-breathing layers 22 and 26 disposed outside and inside the first layer 24 is a vacuum. A heat insulating material 32 and a non-breathable coating material 34 are laminated.
According to the embodiment, at least one of the non-air-permeable layers 22 and 26 is configured by laminating the vacuum heat insulating material 32 and the non-air-permeable covering material 34, so that the heat insulating performance and the gas barrier property can be further improved.

In one embodiment, the heat-insulating layer 20 (20B) shown in FIG. 3 has a non-air-permeable layer 22 and 26 disposed outside and inside the first layer 24, and a vacuum heat-insulating material 32 and a non-air-permeable covering material 34 are laminated. Configured.
According to the above embodiment, the non-air-permeable layers 22 and 26 are configured by laminating the vacuum heat insulating material 32 and the non-air-permeable covering material 34, whereby the heat insulating performance and gas barrier properties can be further improved.

  In one embodiment, as shown in FIG. 7, the non-breathable layers 22 and 26 include a plurality of non-breathable dressings 34 (34a, 34b), and the ends of the non-breathable dressings 34 (34a, 34b). Are arranged so as to overlap each other.

The heat insulating layer covering the surface of the outer wall 28 of the liquefied gas storage tank 12 is configured by laying a plurality of first layers 24, and a seam 36 is formed between adjacent first layers 24.
According to the embodiment, the seams 36 of the first layer 24 can be hermetically sealed by arranging the ends of the plurality of non-breathable covering materials 34 (34a, 34b) so as to overlap each other. It is possible to prevent the heat insulation performance from being deteriorated due to the replacement of the gas in the closed cells of the layer 24.

In one embodiment, as shown in FIG. 7, the non-breathing layers 22 and 26 include a vacuum insulation 32, and a plurality of vacuum insulations 32 are laid down. The joint 38 of the vacuum heat insulating material 32 is disposed at a position shifted from the joint 36 of the first layer 24.
Accordingly, it is possible to suppress a decrease in the heat insulation performance of the joint due to the overlap of the joint 36 and the joint 38.

In one embodiment, as shown in FIG. 1, the liquefied gas storage tank 12 is provided in the liquefied gas carrier ship 10.
The heat insulation layer 20 according to some of the above embodiments eliminates deterioration of heat insulation performance due to replacement with ambient air or an inert gas such as nitrogen gas, and has high heat insulation performance and can be thinned, so that the installation space can be reduced. Therefore, the degree of freedom of arrangement can be expanded even in a liquefied gas carrier ship having a space with limited ship width and ship volume. Moreover, since the weight increase of the heat insulation layer 20 can be suppressed, the deterioration of the operation performance of a liquefied gas carrier ship can be suppressed.

  According to some embodiments, the deterioration of thermal insulation performance due to replacement with ambient air or nitrogen gas is eliminated, and the high thermal insulation performance can be reduced in weight and installation space. Even if it is provided, it can be effectively applied.

DESCRIPTION OF SYMBOLS 10 Liquefied gas carrier 12 Liquefied gas storage tank 20 (20A, 10B, 10C, 10D, 20E, 20F) Thermal insulation layer 22 Outer non-venting layer 24 First layer 26 Inner non-venting layer 28 Outer wall 30 Second layer 32 Vacuum insulating material 34 (34a, 34b) Non-breathable coating material 36, 38 Seam b Closed cell s Gap

Claims (9)

A heat insulating structure for a liquefied gas storage tank having a heat insulating layer covering a surface of an outer wall of the liquefied gas storage tank for storing the liquefied gas,
The thermal insulation layer is
A first layer which is a heat insulating material having closed cells;
A non-breathable layer provided on both sides of the first layer;
Including
At least one of the non-breathing layers provided on both sides of the first layer includes a vacuum heat insulating material in which a core material is covered and sealed with a jacket material having a gas barrier property, and the inside of the jacket material is decompressed. Insulating structure of liquefied gas storage tank. The non-breathing layer includes an outer non-breathing layer provided outside the first layer,
The heat insulation structure of a liquefied gas storage tank according to claim 1, wherein the outer non-venting layer includes the vacuum heat insulating material. The non-breathing layer includes an inner non-breathing layer provided inside the first layer,
The heat insulation structure of a liquefied gas storage tank according to claim 1, wherein the inner non-venting layer includes the vacuum heat insulating material. The thermal insulation layer is
The heat insulation structure for a liquefied gas storage tank according to claim 3, further comprising a second layer, which is a heat insulating material having closed cells, provided inside the inner non-venting layer. The thermal insulation layer is
The heat insulation structure for a liquefied gas storage tank according to claim 4, further comprising a non-breathable covering material provided inside the second layer.   The heat insulation structure for a liquefied gas storage tank according to any one of claims 1 to 5, wherein the other of the non-venting layers provided on both sides of the first layer includes the vacuum heat insulating material.   The heat insulation structure for a liquefied gas storage tank according to any one of claims 1 to 5, wherein the other of the non-breathing layers provided on both sides of the first layer is a non-breathable covering material.   The heat insulation structure for a liquefied gas storage tank according to any one of claims 1 to 7, wherein the non-breathing layer includes a plurality of non-breathable coating materials arranged such that end portions thereof overlap each other. .   The said liquefied gas storage tank is provided in the liquefied gas carrier ship, The heat insulation structure of the liquefied gas storage tank as described in any one of Claim 1 to 8 characterized by the above-mentioned.

Images