KR20140006303A - Insulation structure for lng carrier - Google Patents

Abstract

An insulation structure for an LNG carrier is disclosed. The insulation structure for an LNG carrier for the GTT NO 96 type storage tank insulation structure of an LNG carrier for carrying LNG according to the present invention comprises an insulation box having a closed space inside and a circulation hole for circulating inert gas; and a multilayered insulation material which is arranged at a joint inside the insulation box and which is made of an aluminum thin plate and glass fiber.

Description

Insulation Structure For LNG Carrier

The present invention relates to a heat insulating structure of the LNG carrier, and more particularly, to a heat insulating structure of the LNG carrier is improved by including a multi-layer heat insulating material consisting of aluminum sheet and glass fiber.

Natural gas is a fossil fuel containing methane as a main component and a small amount of ethane, propane, and the like, and has recently been regarded as a low-pollution energy source in various technical fields.

Natural gas is transported in a gaseous state through land or sea gas pipelines, or is transported to a remote location where it is stored in an LNG carrier in the form of liquefied natural gas (LNG). Liquefied natural gas is obtained by cooling natural gas to cryogenic temperature (below -163 ℃ or less), and its volume is reduced to approximately 1/600 than natural gas in gas state, so it is very suitable for long distance transportation by sea.

The liquefied natural gas carrier is equipped with a cargo (also referred to as a storage tank) capable of storing and storing liquefied natural gas that has been liquefied by cooling the natural gas. Since the boiling point of liquefied natural gas is about -162 ° C at atmospheric pressure, the liquefied natural gas cargo hold is made of materials that can withstand extremely low temperatures such as aluminum steel, stainless steel and 35% nickel steel to safely store and store liquefied natural gas And is designed to be resistant to thermal stress and heat shrinkage, and to prevent heat penetration.

LNG RV (Regasification Vessel), which transports LNG carrier and LNG for loading and unloading LNG to land demand by loading LNG and landing in natural gas, Floating marine structures such as LNG FPSO (Floating, Production, Storage and Offloading) and LNG FSRU (FSRU) also include storage tanks installed in LNG carriers or LNG RVs.

LNG FPSO is a floating marine structure that is used to liquefy natural gas produced directly from the sea and store it in a storage tank and, if necessary, to transfer the LNG stored in this storage tank to an LNG carrier. In addition, the LNG FSRU is a floating type of floating structure that stores LNG unloaded from LNG carriers in offshore sea, stores it in a storage tank, vaporizes LNG if necessary, and supplies the LNG to the customer.

In this way, a storage tank for storing LNG in a cryogenic condition is installed in a marine structure such as an LNG carrier, LNG RV, LNG FPSO, and LNG FSRU that transports or stores a liquid cargo such as LNG.

Such a storage tank can be classified into an independent tank type and a membrane type depending on whether the load of the cargo directly acts on the heat insulating material. Membrane type storage tanks are divided into GTT NO 96 type and TGZ Mark III type, and independent tank type storage tanks are divided into MOSS type and IHI-SPB type.

The above-described GTT type and TGZ type tank structures are disclosed in U.S. Patent Nos. 6,035,795, 6,378,722, 5,586,513, and U.S. Patent Publication Nos. 2003-0000949 and the like, and Korean Patent Publication Nos. 10-2000-0011347 and 10-2000- 0011346 and the like. In addition, the structure of the independent tank type storage tank is described in Korean Patent Nos. 10-15063 and 10-305513.

The GTT NO 96 type storage tank includes a primary sealing wall and a secondary sealing wall made of Invar steel (36% Ni) having a thickness of 0.5 to 1.5 mm, a plywood box and a perlite. The primary heat insulation wall and the secondary heat insulation wall which consist of) are alternately laminated and installed on the inner surface of a ship body.

In the case of the GTT NO 96 type, the primary sealing wall and the secondary sealing wall have almost the same degree of liquid tightness and strength, so that when the primary sealing wall leaks, the secondary sealing wall alone can safely support the cargo. . In addition, since the membrane of GTT NO 96 type is linear, it is easier to weld than TGZ Mark Ⅲ type corrugated membrane, and the rate of automation is higher than that of TGZ Mark Ⅲ type. However, overall welding length is longer than that of TGZ Mark Ⅲ type. In the case of GTT NO 96 type, a double couple is used to support an insulation box (ie, an insulation wall). French Patent Nos. 2146612, 2629897, 2683786 and the like disclose a configuration and fixing method of a conventional GTT NO 96 type insulation box.

1 is a perspective view of a heat insulation box used in the GTT NO 96 storage tank according to the prior art installed inside the hull (S). In FIG. 1, the conventional heat insulation box is shown with the heat insulation material removed to show its internal structure. The conventional GTT NO 96 type thermal insulation box constituting the primary thermal insulation wall and the secondary thermal insulation wall 20 in FIG. 1 has a substantially rectangular parallelepiped shape.

A plurality of horizontal members 11 extending in the horizontal direction for reinforcement are installed in the conventional heat insulation box 10, and a fixing member protruding from the heat insulation box to fix the heat insulation box to the inner surface of the hull. do.

In the conventional thermal insulation box, since the horizontal member for reinforcement made of plywood, which is an expensive material, is densely arranged inside the thermal insulation box to satisfy the strength required for the thermal insulation box, the proportion of pearlite, which is a relatively primary thermal insulation material, is reduced. Rather, it may result in poor insulation performance. Therefore, there is a need for a solution that meets structural stiffness and can compensate for the degradation of insulation performance due to the installation of multiple plywood horizontal members.

The present invention is to solve the conventional problems as described above, by including a multi-layer heat insulating material made of aluminum sheet and glass fiber in the GTT NO 96 cargo hold insulation structure of LNG carriers carrying liquefied natural gas, plywood By maintaining the structural stiffness to compensate for the resulting thermal degradation.

According to an aspect of the present invention, in the GTT NO 96 type cargo hold insulation structure of the LNG carrier carrying liquefied natural gas,

A heat insulation box having a closed space formed therein and having a circulation hole for circulating inert gas; And

The insulation structure of the LNG carrier is provided at the seam inside the insulation box and includes a multilayer insulation made of aluminum sheet and glass fiber.

The multi-layer heat insulating material is characterized in that the sandwich structure consisting of a plurality of glass fiber plates are laminated between the aluminum thin plate.

The insulation box may include a primary insulation box that primarily insulates the liquefied natural gas, and a secondary insulation box that is disposed between the primary insulation box and an inner wall of the hull to insulate the liquefied natural gas secondaryly. Can be.

The insulating box is a top and bottom plate made of plywood (plywood), a plurality of vertical members arranged to extend in the horizontal direction between the top and bottom plates for structural rigidity of the heat insulation box, and the heat insulation box is the inner surface of the hull It may include a fixing member for fixing to.

The multi-layered insulating material may be stapled and fixed to the entirety of at least one of the upper and lower plates to be in contact with the plurality of vertical members.

The multilayer insulating material may be manufactured in plural to extend in the horizontal direction along the plurality of vertical members, and may be interposed in a contact portion of at least one of the plurality of vertical members and the upper and lower plates.

According to another aspect of the present invention, there is provided a ship or offshore structure provided with an LNG storage tank including an insulating structure of the LNG carrier.

The insulation structure of the LNG carrier of the present invention is to include a multi-layer insulation made of aluminum sheet and glass fiber in the GTT NO 96 cargo hold insulation structure of LNG carriers carrying liquefied natural gas, while maintaining the structural rigidity by the plywood As a result, the deterioration of insulation performance can be compensated for.

Figure 1 schematically shows the internal structure of the insulation box in a state in which the cargo hold and the insulation of the vessel equipped with a conventional GTT NO 96 type insulation box.
Figure 2 schematically shows the heat insulation structure of the LNG carrier according to an embodiment of the present invention.
3 is a cross-sectional view taken along the line C of FIG. 2.
Figure 4 schematically shows an insulating structure of the LNG carrier according to another embodiment of the present invention.
5 is a cross-sectional view taken along the line C of FIG. 4.
6 is a photograph and a schematic cross-sectional view of a mock-up produced for experiments in accordance with embodiments of the present invention.
7 is a graph tracking the temperature change of Comparative Example 1 in the experiment.
8 is a graph tracking the temperature change of Example 2 in the experiment.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings.

2 and 3 schematically show the heat insulation structure of the LNG carrier according to an embodiment of the present invention.

As shown in Figure 2, the insulation structure of the LNG carrier according to an embodiment of the present invention, in the GTT NO 96 cargo hold insulation structure of the LNG carrier carrying a liquefied natural gas, a closed space is formed therein The insulation box 100 is provided with a circulation hole for circulating the inert gas, and is provided in the seam of the interior of the insulation box 100 and includes a multilayer insulation material 200 made of aluminum sheet and glass fiber.

The multilayer insulation 200 is a sandwich structure in which a plurality of glass cloth plates are stacked between aluminum foils.

Given that the temperature of the LNG is a cryogenic temperature of -163 ℃ or less, the multilayer insulation 200 should be made of a material having physical stability at such a low temperature. In addition, as used for insulation in the insulation structure, the thermal conductivity must be low and must be able to be fixed to the insulation box (100). As such a material, this embodiment adopts a thin aluminum sheet and glass fiber, and proposes a multilayer heat insulating material 200 made of them.

Through the following examples and the thermal insulation experiment was examined the configuration of the optimal multilayer insulation (200).

For optimal multilayer insulation Examples and  Adiabatic test

1) Embodiment

The thickness of the aluminum sheet used in the examples is 0.15 mm, the thickness of the glass fiber is 0.18 mm.

No. Composition of Insulation Placement range Comparative Example 1 none Comparative Example 2 Standard Thermal Protection part Example 1 Aluminum sheet + 10 glass fibers Front Example 2 Aluminum Lamination + 10 Glass Fiber + Aluminum Lamination Front Example 3 Aluminum sheet + 5 sheets of glass fiber (thickness 0.64㎜) + aluminum sheet Front Comparative Example 3 Aluminum Lamination + Two Ceramic Fibers + Aluminum Lamination Front

2) Experimental results

Insulation test is to produce a mock-up (Mock-up) each equipped with a multi-layer insulation 200 in the insulation box 100 and placed in the room at room temperature to achieve thermal equilibrium, then set the cryogenic state at the top and the multilayer insulation is The change in temperature at the bottom of the mockup was observed. A photograph and a schematic cross section of the manufactured mock-up are shown in FIG. 6.

To obtain the average temperature change data, three temperature sensors were attached to the bottom of the model to calculate the average value. Temperature changes were tracked for 46 hours after cryogenic setting. Among them, graphs tracking the temperature change of Comparative Example 1 and Example 2 are shown in FIGS. 7 and 8.

Each temperature data after 46 hours is shown in the following table.

No. Weight of insulation Temperature value measured at each sensor (℃) Temperature average value (℃) Comparative Example 1 - -103.4, -115.4, -112.5 -110.5 Comparative Example 2 1.6t -82.1, -76.2, -100 -86.1 Example 1 1.95 t -56.5, -48.8, -58.2 -54.5 Example 2 2.1t -41, -56.2, -63.4 -53.5 Example 3 1.9t -56.2, -61, -70 -62.4 Comparative Example 3 2.3t -75.8, -73.7, -64.6 -71.4

Through the data in Table 2, when comparing Examples 1, 2, 3, it can be seen that the more the number of laminated glass fibers than the weight of the heat insulating material, the better the heat insulating effect. In other words, even if similar weight, rather than thick glass fiber, it is effective to insulate a plurality of layers and lamination in multiple layers. Comparing Comparative Example 3 and Examples, it can be seen that the weight of Comparative Example 3 is rather heavy, but the heat insulating effect is inferior to the Examples. In addition, by attaching to the exposed both sides of the glass fibers laminated in a thin aluminum plate, radiant heat transfer and convective heat transfer can be minimized. It can be seen that the multilayer insulation produced through the lamination of the insulation members exhibits sufficient insulation effect even in a non-vacuum environment.

Putting these results together, lighter insulation can be made by stacking multiple layers of thin glass fibers instead of thick glass fibers to achieve a similar thermal insulation effect. Light insulation is easy to handle and can reduce the load on the ship when applied to the cargo hold of the ship.

In conclusion, in this embodiment, the thickness of the aluminum sheet may be 0.05 mm to 0.50 mm, and the thickness of the glass fiber may be 0.05 mm to 0.8 mm. Preferably, the thickness of the aluminum sheet is 0.15 mm, the thickness of the glass fiber is 0.18 mm, it was confirmed that the multi-layer heat insulating material laminated 10 sheets of glass fibers and wrapped in aluminum foil like sandwiches on both exposed surfaces is the best in terms of thermal insulation effect.

The insulation box 100 may include a primary insulation box that primarily insulates the liquefied natural gas, and a secondary insulation box that is disposed between the primary insulation box and the inner wall of the hull to insulate the liquefied natural gas secondaryly. have.

The insulation box 100 may include a heat insulator filled in the internal space, and a representative example of the heat insulator may be perlite.

The insulation box 100 includes a plurality of vertical members arranged horizontally between the upper and lower plates 110 and the upper and lower plates 110 for structural stiffness of the insulation box 100. 120 and a fixing member 130 for fixing the heat insulation box 100 to the inner surface of the hull.

A circular circulation hole is formed in the vertical member 120 including the front and rear wall members of the insulation box 100 to circulate the inert gas (for example, nitrogen) in preparation for the leakage of LNG.

2 and 3, in this embodiment, the multilayer insulation 200 is stapled and fixed to the entirety of at least one of the upper and lower plates 110 to be in contact with the plurality of vertical members 120. have.

That is, the multi-layer heat insulating material 200 is fixed by stapling to either or both of the top and bottom plates 110, the plurality of vertical members 120, or between the multi-layer heat insulating material 200, or a multi-layer heat insulating material is not provided It is fixed in a suitable manner, such as stapling, bonding, fitting between the upper and lower plates 110 and the multilayer insulation (200).

For example, prior to fixing to the plate 110 to temporarily seal the aluminum sheet and glass fiber layers to form a multi-layer insulation (200), temporarily fixed to the plate 110 to be fixed with an adhesive and a vertical member After arranging 120, the joining is finished by stapling.

The plywood has a higher thermal conductivity than the pearlite filled for the insulation, and the portion in which the vertical member 120 made of the plywood is arranged is inferior in insulation to the place where the pearlite is filled. Therefore, in this embodiment, the heat insulating property is increased through the multi-layer heat insulating material 200 interposed between the vertical member 120 made of plywood and the upper and lower plates 110.

4 and 5, in another embodiment of the present invention, the multilayer insulation 200 is formed in plural to extend in a horizontal direction along the plurality of vertical members 120 and the plurality of vertical members 120. It may be interposed in the contact portion of at least one of the upper and lower plates 110.

Since the pearlite filled in the heat insulation box 100 has sufficient heat insulating property, the multilayer heat insulating material 200 is interposed only on the vertical member 120 having a relatively low heat insulation effect. Through this, while supplementing the thermal insulation of the vertical plywood member 120, it is possible to reduce the cost by reducing the installation area of the multi-layer heat insulating material 200 compared to when installing the multi-layer heat insulating material 200 on the upper and lower plates 110.

According to another aspect of the present invention, there is provided a ship or offshore structure provided with an LNG storage tank including an insulating structure of the LNG carrier.

For example, such vessels or offshore structures may be floating offshore structures such as LNG carriers, LNG Regasification Vessels, LNG Floating, Production, Storage and Offloading (FPSO) or LNG Floating Storage and Regasification Units (FSRUs).

As described above, the insulation structure of the LNG carrier of this embodiment is to include a multi-layer insulation 200 made of aluminum sheet and glass fiber in the GTT NO 96 cargo hold insulation structure of the LNG carrier carrying liquefied natural gas, While maintaining the structural rigidity caused by plywood, it is possible to compensate for the deterioration of thermal insulation.

In this embodiment, since the insulation performance of the LNG cargo hold is improved, it is possible to reduce the occurrence of Boil-Off Gas (BOG) in the LNG storage tank due to the cargo hold temperature rise when the insulation performance is lowered. Since natural gas is liquefied at cryogenic temperature of -163 ℃, LNG is easily vaporized by temperature change, and evaporation gas generated from storage tank is about 0.05 vol% / day, and it is 4 to 6 tons per hour when operating conventional LNG carrier. (t) A significant amount of liquefied natural gas, once operated, has been vaporized. The BOG is bulky and has a high risk of explosion, thereby reliquefying it. In this embodiment, the BOG may be reduced and the burden of reliquefaction may be reduced by increasing the insulation performance of the cargo hold.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Accordingly, such modifications or variations are intended to fall within the scope of the appended claims.

100: insulation box
110: top and bottom plate
120: vertical member
130: Fixing member
200: multilayer insulation

Claims (7)

In the insulation structure of GTT NO 96 type cargo hold of LNG carriers carrying liquefied natural gas,
A heat insulation box having a closed space formed therein and having a circulation hole for circulating inert gas; And
The insulation structure of the LNG carrier ship is provided in the seam of the insulation box and includes a multilayer insulation made of aluminum sheet and glass fiber. The method of claim 1, wherein the multilayer insulation
An insulating structure of a LNG carrier, characterized in that the sandwich structure is formed by laminating a plurality of glass fiber plates between the aluminum thin plate. According to claim 1, wherein the insulating box
A primary insulation box for insulating the liquefied natural gas primarily; And
The insulation structure of the LNG carrier, characterized in that it comprises a secondary insulation box disposed between the primary insulation box and the inner wall of the hull secondary insulation of the liquefied natural gas. The method of claim 3, wherein the insulating box
Upper and lower plates made of plywood;
A plurality of vertical members arranged in a horizontal direction between the upper and lower plates for structural rigidity of the insulating box; And
The insulation structure of the LNG carrier, characterized in that it comprises a fixing member for fixing the insulation box to the inner surface of the hull. 5. The method of claim 4,
The multi-layer heat insulating material is a stapling (stapling) fixed to the whole of at least one of the upper and lower plates insulated structure of the LNG carrier, characterized in that the contact with the plurality of vertical members. 5. The method of claim 4,
The multi-layered heat insulating material is a plurality of manufactured so as to extend in the horizontal direction along the plurality of horizontal members and the insulating structure of the LNG carrier, characterized in that interposed in the contact portion of at least one of the plurality of vertical members and the upper and lower plates. The ship or offshore structure provided with the LNG storage tank containing the heat insulation structure of the LNG carrier in any one of Claims 1-6.

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