KR830000804B1 - Insulated marine container for liquefied gas - Google Patents

Abstract

A cryogenic liquefied gas container for a ship or barge includes a metal tank(13) shaped as a surface of revolution and external thermal insulation including a layer of foamed plastics panels(33,37) each with at least four holes(39) receiving smaller diameter studs(29) fixed to the tank(13), and fibrous insulation(41) filling the holes(39) around the studs(29). Insulating posts(31) are joined to and extend outwardly from the studs(29), and insulation fills the joints between panels(33,37). The posts(31) have end fasteners(49) contacting the outer layer outer surface.

Description

Liquefied gas insulated container

1 is a longitudinal sectional view showing that the heat insulation container according to the present invention is installed in a ship.

2 is an enlarged partial perspective view of a portion of the spherical container with a heat insulation layer installed on it.

3 is an enlarged longitudinal section just below the middle of the container of FIG.

4 is a cross-sectional view taken along line 4-4 of FIG.

5 is a cross-sectional view taken along line 5-5 of FIG.

6 is an enlarged cross-sectional view of the upper portion of FIG.

7 is a schematic view showing the insulation device and the installation procedure similar to that of FIG.

The present invention relates in particular to thermal insulation systems used in conjunction with storage of large marine containers or liquefied gas for ship transport and containers for use in ships, where the system minimizes the flow of ambient heat into the container, It is to enable liquefied gas retention below that.

Several schemes have been developed for sea transport of liquefied gas, for example large containers such as spherical tanks of 100 feet or more in diameter. Several systems have been developed to insulate large marine tanks, to insulate the inside or outside of the metal tank walls and maintain the pressure within the tank at 1-3 atmospheres to maintain the temperature at or below the liquefied gas. However, improved thermal insulation systems are still being developed in large marine tanks, especially older tanks.

The present invention provides an improved thermal insulation system adapted to insulate the exterior of large spherical metal tanks with a high thermal insulation effect that does not deteriorate even after years of use. A system having such an insulating effect can maintain the liquefied gas at a boiling loss of 0.25% or less per day without the need for a separate auxiliary refrigeration system. The present invention provides an improved method for producing spherical thermal insulation tanks for sea transport or storage of liquefied gas. The present invention will be understood in more detail with reference to the drawings.

In FIG. 1 is an example of one of the metal tanks 13 arranged in the vessel 11 and the other tanks are of similar size. Each tank is of similar size. Each tank is spherical and is supported on a ship by a metal skirt 15 and the tank and skirt are connected by a ring of tank caution 17 at the equator of the tank 13.

The lower part of the metal skirt 15 is connected to the appropriate part of the hull 19 by welding. The tank 13 protrudes over the main deck 21 of the ship and is covered with a cover 23 to protect the user from wind or sea water during the voyage. The cover 23 is prevented from leaking air, and the area between the tank and the cover and the area around the tank in the vessel 19 with inert gas can be secured if the liquefied gas is volatile or dangerous.

This general type of ship 11 is widely used to transport things like liquefied natural gas (LNG), which is usually methane with a boiling point of -161 ° C. The thermal insulation system is therefore designed to minimize heat flow between the inner metal tank of aluminum at -161 ° C and the ambient temperature in the range from 0 ° C to 45 ° C.

인치와 7인치 사이의 두께를 가진 알루미늄판으로 용접되어 있으며 탱크위에는 원통형의 돔(27)이 있다. 제 3 도에서 보듯이 용기중간의(적도에 해당하는) 부분(17)은 스커트(15)와 연결될 수 있는 구조의 환형으로 되어 있다. 링(17)의 본체상하 가장자리는 용점으로 용기(25)의 상한 반구형의 반쪽부분에 상호연결되어 있다.The tank 13 has a spherical metal container 25 which is usually

There is a cylindrical dome 27 welded on an aluminum plate with a thickness between inches and 7 inches. As shown in FIG. 3, the portion 17 of the vessel (corresponding to the equator) has an annular structure that can be connected to the skirt 15. The upper and lower edges of the main body of the ring 17 are interconnected to the upper half hemispherical half of the container 25 by melting point.

As shown in FIG. 1, the thermal insulation system outside the metal container 25 is made of a panel of synthetic resin material having a density of about 1.5-2.5 pounds per cubic foot, and foam polyurethane is commonly used. As can be seen in FIG. 6, the panel is welded to the surface of the vessel using a known technique using a Nelson Stud as described below on the outer surface of the spherical metal container 25. Is supported. The stud 29 is about 3 inches long and houses a long threaded rod 31 made of a material having a threaded hole on the outside and having good thermal insulation properties. The rods 31 shown in the figure are each about 7 inches long.

As the heat insulation system, three layers of heat insulation layers are used. As the innermost first layer, a 2 inch thick polyurethane panel 33 is used. The second layer is a 1/2 inch thick fiberglass mat 35 and the third layer consists of a 6 inch thick polyurethane foam in three layers of a 2 inch thick panel 37.

인치이다. 이러한 배열로 하여 대형 금속제 탱크에 단열계를 설치하는데 있어서 제 1층의 판넬(33)을 스터드(29)를 설치하고 고정시키기 위한 형판으로 사용하여 쉽게된다. 제 7 도에서와 같이 판넬(33)은 금속제 용기(25)의 외부표면의 요구되는 자리에 위치되며 스터드 용접기(40)의 머리부분이 확대된 구멍(39a)에 수용되며 여기에서 구멍(39a)이 있는 금속제 탱크벽에 스터드(29)를 고정시키도록 구명의 벽에의해 안내가 된다. 스터드(29)를 설치한 후 각 구멍(39a)의 빈공간은 화이버글라스(41)로 채워진다.As shown in FIG. 2, each of the panels 33 and 37 has six holes 39 in a unique form, and four holes may be used even though six holes are provided. In FIG. 6 the hole 39a of the first layer of panel 33 is much larger than the stud, with the stud being 5/8 inch in diameter and the hole 39 being

Inches. This arrangement makes it easy to use the panel 33 of the first layer as a template for installing and fixing the studs 29 in installing an insulation system in a large metal tank. As in FIG. 7, the panel 33 is located at the required position on the outer surface of the metal container 25 and the head of the stud welder 40 is received in the enlarged hole 39a where the hole 39a is located. It is guided by the wall of the lifejacket to fix the stud 29 to the metal tank wall. After the stud 29 is installed, the empty space of each hole 39a is filled with the fiberglass 41.

If panels 33 and 35 are preferably foamed with an aluminum foil stack on kraft paper, there is a urethane foam that gives good adhesion to the kraft paper surface and such an integrated layer can be applied to the opposite surface of the panel. By treating the panel 33 with a layer of foil adjacent to the surface of the aluminum container 25, relative movement between them is possible. Attaching such integrated layers to one or both surfaces of the panel provides reinforcement and preserves the unit's integrity even if the foam cracks later. Panel 33 is positioned so that a gap 43 of about 1.5 inches is formed around the entire circumference of each panel and the gap 43 is filled with fiberglass 45 having a density of about 2-3 pounds per cubic foot. .

As shown in FIGS. 6 and 7, the length of the welded stud 29 is sufficient to protrude out of the surface of the panel 33 of FIG. 1 and to support the second layer of fiberglass 35. The first layer 35 is continuous and is made of fiberglass having a thickness of about 1/2 inch and a density of about 2 pounds per cubic foot. The fiberglass layer 35 provides a continuous, thin hemispherical region outside the upper and lower halves of the aluminum container 25.

Furthermore, each of the urethane panels 33 of the first layer is surrounded by fiberglass at four corners and at the boundary of six holes 39a at the outer surface. With this arrangement, the inner layer of the panel 33 can move freely with respect to the outer surface of the metal container 25.

When the low temperature liquid is filled in the tank 13, the aluminum wall of the container 25 is thermally reduced and its shrinkage is different from that of the polyurethane panel 33 which has a higher coefficient of thermal expansion than the aluminum plate. Therefore, since the first layer panel 33 is contracted relative to the surface of the metal sphere 25, sliding occurs on the proximal surface, and the hole 39a with a large hole does not generate structural stress caused as a result of the thermal contraction or expansion in the panel. And move relative to the welded stud 29.

The long insulation rod 31 is screwed into the stud 29 to support the third layer of foam polyurethane 6 inches thick. This six inch layer consists of three two inch thick polyurethane panels 37 having the same characteristics as the panel 33 used in the first layer. The same panel of 6 inches thick can also be used respectively. In FIG. 2, each of the panels 37 has a six-hole shape, but the holes 39 are not only smaller in diameter than the holes 39a of the panel 33 in the first layer (see FIG. 6), respectively. Will be in position.

As a result, the gap 47 between the circumferential edges of the panel 37 of the third layer is staggered with the gap between the panel 33 of the first layer, which opens between the wall of the metal sphere 25 and the outer surface of the thermal insulation system. To minimize the passage.

After each group of three 2-inch panels covering a third layer of insulation is installed on the threaded rod 31, an appropriate anchor 49 is applied to the outer end of the rod to secure the panel in place.

The described fastener 49 has a center hole that is a screw plate to fit into the threaded portion of the end of the metal rod 31 as a flat nut or torque washer. The fixture 49 is cast from a suitable plastic material, such as acetyl resin, and as shown in FIG. 6, the fixture 49 has several passageways 51 between each metal rod 31 and the side wall of the hole 39 of the panel 37. Connect the empty spaces. Polyurethane is filled through this passageway 51 into this zone and filled to fill this zone with insulating material or foamed to better adhere the panels to the metal rods. After the three-ply panel layer is attached to the spherical surface portion, the gaps 47 between the circumferences of the panel 37 are filled with foamed polyurethane 48 to seal the entire 6 inch thick thermal barrier in the second insulating layer 35. Will be provided.

After all panels 37 of the third layer have been installed and the gaps 47 between the panels 37 and the area around the metal rods 31 are filled with foamed polyurethane, the outer protective cover 53 is supported by the support skirt. Applied to the outside of the heat insulating sphere comprising (15). This protective cover 35 must be airtight and able to withstand the marine environment. Moreover, the protective cover on the other side should be able to prevent the erosion of sea water and the like when the tank 13 is loaded on the ship by the cargo ship. The protective cover 53 should be sprayed with elastomeric material, and should be uniformly sprayed with a layer of butyl rubber on the outer surface of the insulated tank 13 with a thickness of 0.025 inch, and sheathed with a thin urethane elastomer.

For example, a light weight and effective thermal insulation system, such as a spherical tank weighing less than 60 tons, a diameter of 120 feet, and an exhaust system should be provided to prevent leakage of liquefied gas through the walls of the metal container 25. In this regard, the thin, hemispherical cell of the continuous second layer of the fiber glass 35 serves as a passage in the leakage of the liquefied gas, and the fiber glass 41 and the first layer panel (filling the area around the studs 29). The fiberglass 45 filling the gap 43 between 33 connects the outer surface of the aluminum container 25 with this thin, continuous hemispherical cell.

In the lower half of the tank 13 of FIG. 1, a discharge line 57 is provided and extends in the lower portion of the outer cell of the thermal insulation system. The piping connected to this discharge line 57 has a safety valve 59 which opens at a pressure as low as 1.02 atmosphere and discharges the leaked material to the leak collection plate 61 under each tank and at the lower part of the hull 19. do. Line 63 from outlet 57 extends upward through valve 63 to sampling pump 67 to check periodically for leaks.

Accordingly, when the upper valve 65 is opened and the sampling pump 67 is operated, a slight vacuum is applied to the thin hemispherical cell to determine whether there is a leak, and it is possible to know where there is a leak in the lower hemisphere of the metal container.

As shown in Figures 1 and 3, the same device is provided in the upper hemisphere. The outside of the cell 35 filled with thin fiberglass in the upper hemisphere extends into the space portion 66 outside the equatorial ring 17 of the tank. The thin cell 35 thus acts as a passage to this annular space 66. An additional fiberglass layer 68 is provided on the outer side of the skirt 15 as part of the thermal insulation and makes a second space portion 69. The skirt 15 is hardened by a reinforcement ring 71 extending in cross section and horizontally, the reinforcement ring 71 being properly insulated with fiberglass 73 and polyurethane panel 75, as shown in the figure. However, they are properly attached by studs and posts as described for the outer surface of the sphere.

Collecting conduit 81 is installed under the space portion 69 and extends downward through the hole between the reinforcing rings 71 and is bent at 90 ° and connected to the discharge tube 83 extending outward through the protective insulating cover. have. In FIG. 1 the discharge tube 83 is connected to the pipe as described above. One leg 85 in the pipe extends downward through the hole in the skirt to the safety valve 87 on the leak collector plate 61. Another leak 89 extends upward through the valve 91 to the sampling pump 93 and can be checked in the same manner as before. Furthermore, if the liquefied gas leaks, the safety valve opens and the leak collects in the leak collecting plate 61 to be vaporized or removed by another device.

By providing an airtight barrier outside the insulated tank, the area between the protective cover 53 and the cover 23 is slightly pressurized with an inert gas such as nitrogen for safety and the entire insulator system minimizes heat flow to the liquefied gas. It will be effective. In this regard, in tanks containing LNG (boiling point of methane about -161 ° C), the boiling loss of 70 ° F around the tank in the tank is limited to 0.16% per day. This amount is commercially acceptable and can be effectively used as part of the ship's propulsion.

In addition, the polyurethane panel described above has a compressive strength that is sufficient to support the insulated tank and to withstand sea transportation during installation.

Claims (1)

A spherical metal tank 25 for storing the liquefied gas at low temperature, a device for supporting the tank on the vessel and a single barrier surrounding the outer surface of the vessel to maintain the low temperature by minimizing external heat flow into the vessel In a container with a heat insulating barrier, the thermal barrier is formed of three layers, the first layer of which consists of panels 33 of foam material, in which four or more holes 39 are drilled in a constant shape. The diameter of the stud 29 attached to the outer surface of the tank 25 is smaller than the hole of the panel 33 and penetrates through the panel, and the fibrous insulation 41 fills the hole area around the stud, and the post (POST) of the insulation ( 31) is connected to the stud and extends in the axial direction, and the insulator 45 is filled in the outer periphery of the adjacent panels of the first layer, and the second layer is made of fibrous insulator 35.It is inserted into the base studs and the post unit, and surrounds the outer surface of the first layer, and the third layer is panels 37 of foam polymer material, with holes for several posts being drilled in the first layer panel 33. Since the shape is the same, but the position of the panel around the panel is different, the connection part between the third-layer panels is drilled so as to deviate from the first-layer panel, and the fasteners 49 Insulation container for storage of liquefied gas with).

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