KR20210131481A - Lng strorage tank - Google Patents

Abstract

The present invention relates to an LNG storage tank. The LNG storage tank of the present invention comprises an insulating structure disposed on the outer surface of a tank main body. The insulating structure comprises: a flexible polyurethane foam layer having a specific range of elongation; a rigid polyurethane foam layer; and a high elongation polyurethane layer having the specific range of elongation. An objective of the present invention is to provide the insulating structure with significantly improved crack prevention performance in an environment of rapid temperature change, and the LNG storage tank to which the same is applied.

Description

LNG storage tank {LNG STRORAGE TANK}

The present invention relates to an LNG storage tank.

In general, liquefied natural gas (LNG) refers to a cryogenic liquid in which the volume is reduced by compressing, cooling, and liquefying hydrocarbon-based natural gas to -163° C. for transportation and convenience.

As a clean energy, LNG is attracting attention as an alternative energy to replace petroleum-based energy. Accordingly, LNG demand and trade are gradually increasing.

In line with this trend, research and development of LNG carriers are being conducted. In particular, an LNG carrier necessarily has an LNG storage tank capable of storing cryogenic LNG, and its performance is directly related to the amount of trade in LNG, so research and development of the LNG storage tank is continuously required.

In order to store cryogenic LNG, the LNG storage tank has an outer surface protected by a thermal insulation material. Such a thermal insulation material is required to have a certain level of strength to withstand the load of LNG (eg, sloshing load) as well as excellent thermal insulation performance.

In the case of the prior art, in accordance with the above-mentioned requirements, a rigid polyurethane foam excellent in thermal insulation performance and tensile strength is employed as an insulator of an LNG storage tank. However, the LNG storage tank has a rapid temperature change according to the inflow and outflow of LNG, and the rigid polyurethane foam has a fatal problem that cracks are easily formed in such an environment.

Accordingly, in order to prevent crack formation, a technique of using a flexible polyurethane foam and a rigid polyurethane foam together in a laminated structure has been proposed. However, this also has a problem of insufficient crack prevention performance.

Therefore, it is necessary to develop an insulating structure having excellent crack prevention performance in an environment of rapid temperature change, and an LNG storage tank to which the same is applied.

Republic of Korea Patent Publication No. 10-1273433

An object of the present invention is to provide an insulating structure having significantly improved crack prevention performance in a sudden temperature change environment, and an LNG storage tank to which the same is applied.

The present invention, the tank body for storing LNG; a flexible polyurethane foam layer (A) disposed on the outer surface of the tank body and having an elongation of 100% or more at 25°C; a rigid polyurethane foam layer (B) disposed on the outer surface of the flexible polyurethane foam layer (A); and a high elongation polyurethane layer (C1) disposed on the outer surface of the rigid polyurethane foam layer (B) and having an elongation of 300% or more at 25° C.; it provides an LNG storage tank.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) may have an elongation of 100 to 800% at 25°C, and the high-elongation polyurethane layer (C1) may have an elongation of 600% or more at 25°C.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) may have an elongation of 4% or more at -163 ℃.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) may have a tensile strength of 100 kPa or more at 25 ℃.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) may have a density of 10 to 100 kg/m ³ .

In one embodiment of the present invention, the rigid polyurethane foam layer (B) may have a tensile strength of 200 kPa or more at 25 ℃.

In one embodiment of the present invention, between the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B), it may further include a reinforcing layer.

In one embodiment of the present invention, between the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B), a high elongation polyurethane layer (C2) having an elongation of 300% or more at 25 ° C. can be further included have.

In one embodiment of the present invention, the rigid polyurethane foam layer (B) may have at least one or more reinforcing layers inserted therein.

In one embodiment of the present invention, the high elongation polyurethane layer (C1) may contain a reinforcing material.

In one embodiment of the present invention, the ratio of the thickness of the flexible polyurethane foam layer (A), the rigid polyurethane foam layer (B) and the high elongation polyurethane layer (C1) is 10 to 100: 100 to 400: 1 to 10 days.

In one embodiment of the present invention, the high-elongation polyurethane layer (C1) disposed on the outer surface, it may further include a UV denaturation prevention layer.

The LNG storage tank of the present invention is particularly excellent in thermal insulation performance by introducing a thermal insulation structure with significantly improved crack prevention performance.

1 shows a cross-section of a tank body and a heat insulating structure ((A), (B) and (C1)) of an LNG storage tank according to an embodiment of the present invention.

In this specification, the meaning of a component (eg, layer, etc.) being “disposed on” another component means that a component is disposed directly on another component, or a third component is interposed therebetween. may be placed.

Hereinafter, the present invention will be described in detail.

In the case of a conventional LNG storage tank, in order to secure thermal insulation, a rigid polyurethane foam has been conventionally employed as an insulator surrounding the outer surface of the LNG storage tank. However, the rigid polyurethane foam has a problem in that cracks are easily formed by the temperature change according to the inflow and outflow of LNG in the LNG storage tank, so that the thermal insulation performance is rapidly reduced.

In order to solve this problem, as a thermal insulation structure disposed on the outer surface of the tank body of the LNG storage tank, a technology of using a flexible polyurethane foam and a rigid polyurethane foam together in a laminated structure has been proposed. However, this also has a problem of insufficient crack prevention performance.

Accordingly, the present inventors have continuously studied to solve the above problems,

a flexible polyurethane foam layer having an elongation greater than or equal to a specific value; Rigid polyurethane foam layer; and a high elongation polyurethane layer having an elongation greater than or equal to a specific value; in the case of the laminated insulating structure, it was found that the crack prevention performance was remarkably excellent even in a temperature change environment.

Specifically, the present invention, a tank body for storing LNG; a flexible polyurethane foam layer (A) disposed on the outer surface of the tank body and having an elongation of 100% or more at 25°C; a rigid polyurethane foam layer (B) disposed on the outer surface of the flexible polyurethane foam layer (A); and a high elongation polyurethane layer (C1) disposed on the outer surface of the rigid polyurethane foam layer (B) and having an elongation of 300% or more at 25° C.; It relates to an LNG storage tank comprising.

That is, the LNG storage tank of the present invention includes a thermal insulation structure disposed on the outer surface of the tank body, the insulation structure is the flexible polyurethane foam layer (A); The rigid polyurethane foam layer (B); and the high elongation polyurethane layer (C1).

The heat insulating structure is a combination of (A), (B) and (C1), crack formation can be significantly prevented even in a cryogenic and rapid temperature change environment. Accordingly, it is possible to effectively prevent a sudden decrease in thermal insulation performance due to the formation of cracks appearing in the thermal insulation material of the conventional LNG storage tank.

In addition, the heat insulating structure is a combination of (A), (B) and (C1), and has sufficient strength to withstand the load of LNG (eg, sloshing load) during LNG transportation.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) may have an elongation of 100 to 800% at 25°C, and the high-elongation polyurethane layer (C1) may have an elongation of 600% or more at 25°C. In this case, the crack prevention performance described above may be more excellent.

As the tank body in the present invention, those already known in the art may be employed, and thus, a detailed description thereof will be omitted in this specification. However, for example, the material of the tank body may be aluminum, stainless steel, nickel steel, high manganese for cryogenic use, or the like.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) may have an elongation of 200 to 600% at 25°C, and the high-elongation polyurethane layer (C1) may have an elongation of 650% or more at 25°C. In this case, the crack prevention performance described above may be particularly excellent.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) may have an elongation of 4% or more at -163 ℃, more preferably 8% or more, even more preferably 12% or more. The flexible polyurethane foam layer (A) is the layer most adjacent to the LNG tank body in which LNG is stored among the components of the insulating structure of the present invention, and it is more advantageous to secure the elongation at low temperature in implementing the crack prevention performance. have.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) may have a tensile strength of 100 kPa or more at 25 ℃. In this case, the heat insulating structure of the present invention is more advantageous to withstand the LNG load (eg, sloshing load) during LNG transportation.

In one embodiment of the present invention, the density of the flexible polyurethane foam layer (A) is not particularly limited, but 5 to 850 kg/m ³ , more preferably 10 to 500 kg/m ³ , and even better It may be 10 to 100 kg/m ^{3 .}

In one embodiment of the present invention, the rigid polyurethane foam layer (B) may have a tensile strength of 100 kPa or more at 25 ℃, more preferably 200 kPa or more. In this case, the heat insulating structure of the present invention is more advantageous to withstand the LNG load (eg, sloshing load) during LNG transportation.

In one embodiment of the present invention, between the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B), it may further include a reinforcing layer. In this case, the reinforcing layer is not particularly limited, but a glass wool mat, a mineral wool mat, an iron mesh mat, and the like may be employed.

In some embodiments, a metal sheet such as an aluminum sheet may be further included on the outer surface of the reinforcing layer. In this case, it is possible to directly discharge the boil-off gas from the inside of the LNG storage tank to the outside, or, conversely, prevent the inflow of water vapor into the LNG storage tank from the outside.

In one embodiment of the present invention, between the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B), a high elongation polyurethane layer (C2) having an elongation of 300% or more at 25 ° C. can In this case, the crack prevention performance can be further improved. In this case, the high-elongation polyurethane layer (C2) may be the same as the high-elongation polyurethane layer (C1) or different.

In one embodiment of the present invention, the rigid polyurethane foam layer (B) may have at least one or more reinforcing layers inserted therein. That is, the rigid polyurethane foam layer (B) may have a structure in which a rigid polyurethane foam layer and a reinforcing layer are alternately stacked. For a more specific example, it may be a laminated structure of a rigid polyurethane foam layer/reinforcing layer/rigid polyurethane foam layer. In this case, as the reinforcing layer, without particular limitation, a glass wool mat, a mineral wool mat, an iron mesh mat, or the like may be employed.

In one embodiment of the present invention, the high elongation polyurethane layer (C1) may contain a reinforcing material. In this case, as the reinforcing material, for example, reinforcing fibers such as glass fibers and mineral fibers may be employed.

In one embodiment of the present invention, the ratio of the thickness of the flexible polyurethane foam layer (A), the rigid polyurethane foam layer (B) and the high elongation polyurethane layer (C1) is not particularly limited, but 10 to It may be 100: 100 to 400: 1 to 10. In this case, through the combination of (A), (B) and (C1) having the thickness as described above, it is possible to implement better crack prevention performance.

In one embodiment of the present invention, an ultraviolet (UV) denaturation prevention layer disposed on the outer surface of the high elongation polyurethane layer (C1) may be further included. In this case, the high elongation polyurethane layer (C1) can be prevented from being denatured by ultraviolet rays, and durability can be secured. Accordingly, the excellent anti-crack performance can be maintained for a longer period of time. At this time, the UV denaturation prevention layer is, for example, a commercially available TOTALBOAT's gel coat, Fibreglast's 682, Aekyung Chemical's gel coat, etc. applied on the outer surface of the high elongation polyurethane layer (C1), It can be formed by drying.

Hereinafter, the flexible polyurethane foam layer (A), the rigid polyurethane foam layer (B), the high elongation polyurethane layer (C1) and the high elongation polyurethane layer (C2) will be described in detail.

The flexible polyurethane foam layer (A) may be formed by a flexible polyurethane foam manufacturing raw material and manufacturing method known in the art, without any particular limitation. However, the elongation of the formed flexible polyurethane foam layer should be 100% or more, and thus, it is necessary to appropriately select a manufacturing raw material.

For example, the manufacturing raw material may include polyol, diisocyanate (TDI, MDI, modified MDI, etc.), catalyst, foam stabilizer (silicone surfactant, etc.), foaming agent (H ₂ O, etc.). Incidentally, it may further include a crosslinking agent (DEOA, TEOA, glycerin, etc.) and a chain extender (1,4-butanediol, 1,5-pentanediol, etc.). Other additives (eg, flame retardants, cell openers, cell control agents, etc.) may be further included.

An amine polyol may be used instead of the polyol, or a mixture thereof may be used. The molecular weight of the polyol may be 1000 to 7000, and the molecular weight of the amine polyol may be 1000 to 6000, but is not particularly limited thereto.

The polyol is not particularly limited, but may have an OH value (OHV) of 20 to 50 mgKOH/g, more preferably 30 to 45 mgKOH/g.

In addition, the polyol is not particularly limited, but may be an EO-capped polyol. The EO-capping degree may be 5% or more, more preferably 10% or more, and even more preferably 15% or more. In this case, better elongation can be realized.

For more specific examples, KPX's FA703, KE803, FA 103 as the polyol; BASF's L2095, L2090, L2047, GE 226, etc. may be used. In addition, BASF's MP102, MP105, MM-103C, KC6500/B, KC6005/174, etc. may be used as the diisocyanate. In addition, as the antifoaming agent, Momentive's L3002; Evonik's B8870, O-501; Menover's S702 or the like may be used. In addition, Momentive's A-1, PMDETA as the catalyst; Evonik's TEDA-33LV; DBTDL of Songwon Industries, etc. may be used. Of course, the present invention is not limited thereto.

The rigid polyurethane foam layer (B) may be formed by a rigid polyurethane foam manufacturing raw material and manufacturing method known in the art.

For example, the manufacturing raw material may include polyol, diisocyanate (polymeric MDI, etc.), catalyst, foam stabilizer (silicone surfactant, etc.), foaming agent (CFC-11, HCFC-141b, c-Pentane, etc.). Incidentally, it may further include a crosslinking agent (DEOA, TEOA, glycerin, etc.) and a chain extender (1,4-butanediol, 1,5-pentanediol, etc.). Other additives (eg, flame retardants) may be further included.

An amine polyol may be used instead of the polyol, or a mixture thereof may be used, but is not particularly limited thereto.

The diisocyanate is not particularly limited, but NCO% may be 20% or more, or 30% or more.

The polyol is not particularly limited, but may have an OH value (OHV) of 150 mgKOH/g or more, more preferably 200 mgKOH/g or more.

For a more specific example, HS209, KR500 of KPX as the polyol; BASF's RP-709, TA360, L3700, etc. may be used. In addition, as the diisocyanate, M20S manufactured by BASF may be used. In addition, Evonik's B8409, LK443, etc. may be used as the foam stabilizer. In addition, Momentive's A-1 as the catalyst; Evonik's TEDA-33LV, PC-9; DBTDL of Songwon Industries, etc. may be used. Of course, the present invention is not limited thereto.

In one embodiment of the present invention, the flexible polyurethane foam layer (A) and/or the rigid polyurethane foam layer (B) may be a spray foam layer formed by a spray method. Specifically, it is possible to form the flexible polyurethane foam layer (A) and/or the rigid polyurethane foam layer (B) by injecting a polyurethane manufacturing raw material into the spray equipment, and spraying it directly on the target target surface. Conventionally, in the case of the insulating structure of the LNG storage tank, a method of separately manufacturing a polyurethane foam molded body through a slab, molding molding, etc., and then attaching it on the outer surface of the tank body has been mainly employed. In the case of the prior art, there was a problem that the process is rather complicated and the working time is required for a long time, but the present invention can solve this problem.

The high-elongation polyurethane layer (C1) and the high-elongation polyurethane layer (C2) can be formed, for example, by coating and drying a polyurethane elastomer on the outer surface of the rigid polyurethane foam layer (B). The polyurethane elastomer used to form the high elongation polyurethane layer (C1) and the high elongation polyurethane layer (C2) may be the same or different. However, it should have an elongation of 300% or more.

At this time, as the polyurethane elastomer, if it has an elongation of 300% or more, there is no particular limitation, and those known in the art may be employed. For example, commercially available POLYDOKP 300A/B of Kukdo Chemical Company, UE 9001A/B of Yuwon Platform Company, etc. may be employed.

As a method of forming the high-elongation polyurethane layer (C1) and/or the high-elongation polyurethane layer (C2), a reaction injection molding (RIM) method may be employed. However, the present invention is not limited thereto.

Hereinafter, Examples and Comparative Examples of the present invention will be described.

The elongation at 25° C. was measured perpendicular to the cell direction of the polyurethane foam according to DIN 53 504.

In addition, the elongation at -163°C was measured perpendicular to the cell direction of the polyurethane foam in accordance with DIN 54 504 in a liquid nitrogen chamber.

Tensile strength was also measured according to DIN 53 504.

Density was measured according to DIN 53 479.

[Example 1]

(1) Formation of flexible polyurethane foam layer (A)

A flexible polyurethane foam layer (thickness: about 30 to 40 mm) was formed on the surface of a high manganese steel container through a spray method.

The raw materials used to form the flexible polyurethane foam layer are as follows. With respect to 100 parts by weight of a polyol mixed with 80 parts by weight of KPX's FA703 and 20 parts by weight of BASF's L2095, 1 part by weight of a silicone-based foam stabilizer (Momentive, L3002), 4 parts by weight of a catalyst (Momentive, A-1) After mixing 10 parts by weight of tris(1-chloro-2-propyl) phosphate as a flame retardant and 3.2 parts by weight of water as a foaming agent, a modified MDI curing agent (BASF's KC6005/® NCO 18.4%) was added to the polyol It was used by adding the NCO / OH equivalent of 1.20.

As a result of preparing a specimen and measuring the physical properties, the tensile strength was 225 kPa, the elongation was 245%, the cryogenic (-163°C) elongation was 4.5%, and the density was 57 kg/m ³ .

(2) Formation of the rigid polyurethane foam layer (B)

A rigid polyurethane foam layer (thickness: about 350 to 400 mm) was formed on the surface of the flexible polyurethane foam layer through a spray method.

The raw materials used to form the rigid polyurethane foam layer are as follows. Based on 100 parts by weight of a polyol mixed with 30 parts by weight of KPX's HS 209, 40 parts by weight of BASF's RP-709 and 30 parts by weight of TA360, 10 parts by weight of triethanolamine, 1.5 parts by weight of a silicone foam stabilizer (Evonik, B8409) 1 part by weight of Momentive's A-1 as a catalyst and 3.5 parts by weight of Evonik's TEDA-33LV as a catalyst, 40 parts by weight of tris(1-chloro-2-propyl) phosphate as a flame retardant, 1.5 parts by weight of water as a blowing agent, and After mixing 35 parts by weight of HFCs (HFC245fa from honeywell and HFC365 mfc from Solvay in a 7:3 weight ratio), a polymeric MDI curing agent (M20S from BASF) was added to the polyol with an NCO/OH equivalent of 1.25 It was used by inputting so as to become .

(3) Formation of high elongation polyurethane layer (C1)

A high elongation polyurethane layer (thickness: 3 to 5 mm) was formed on the surface of the rigid polyurethane foam layer through the RIM method.

The raw materials used to form the high elongation polyurethane layer are as follows.

72 parts by weight of polyamine (Jeffamine D2000, Huntsman), 100 parts by weight of a curing agent (SUPRASEC 2054, Huntsman), and 28 parts by weight of a crosslinking agent (Ethyl Corporation, DETDA) were mixed and used.

As a result of preparing a specimen and measuring the physical properties, the elongation was measured to be 349%.

[Example 2]

It was carried out in the same manner as in Example 1, except that a glass wool mat reinforcing layer (20 to 30 mm) was additionally formed between the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B).

[Example 3]

It was carried out in the same manner as in Example 1, except that a high elongation polyurethane layer (C2) having a thickness of 3 to 5 mm was additionally formed between the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B).

The high-elongation polyurethane layer (C2) was formed through the same raw materials and method as the high-elongation polyurethane layer (C1) of Example 1.

[Comparative Example 1]

Except that only the rigid polyurethane foam layer (A) was formed, it was carried out in the same manner as in Example 1.

[Comparative Example 2]

Except that only the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B) were formed, it was carried out in the same manner as in Example 1.

[Evaluation] Crack prevention performance evaluation

Liquid nitrogen was put into the high manganese steel containers of Examples and Comparative Examples, and left at room temperature for 1 week. Then, after removing the liquid nitrogen, it was left at room temperature again for 1 week. This was repeated once, and it was checked whether cracks occurred on the surface of the outermost layer of Examples and Comparative Examples.

The number of trials when cracks first occurred was confirmed and shown in Table 1.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 number 8 10 13 3 5

Referring to Table 1, it can be seen that, in the case of Examples of the present invention, crack prevention performance is superior to those of Comparative Examples.

In particular, in the case of Example 3, it can be seen that the crack prevention performance is significantly superior to that of Comparative Example.

Claims (12)

Tank body for storing LNG;
a flexible polyurethane foam layer (A) disposed on the outer surface of the tank body and having an elongation of 100% or more at 25°C;
disposed on the outer surface of the flexible polyurethane foam layer (A), a rigid polyurethane foam layer (B); and
An LNG storage tank comprising a; disposed on the outer surface of the rigid polyurethane foam layer (B), the elongation at 25 ° C. of 300% or more, the high elongation polyurethane layer (C1). The method of claim 1,
The flexible polyurethane foam layer (A) has an elongation of 100 to 800% at 25°C, and the high-elongation polyurethane layer (C1) has an elongation of 600% or more at 25°C, LNG storage tank. The method of claim 1,
The flexible polyurethane foam layer (A) has an elongation of 4% or more at -163 ℃, LNG storage tank. The method of claim 1,
The flexible polyurethane foam layer (A) has a tensile strength of 100 kPa or more at 25 ℃, LNG storage tank. The method of claim 1,
The flexible polyurethane foam layer (A) has a density of 10 to 100 kg/m ³ , an LNG storage tank. The method of claim 1,
The rigid polyurethane foam layer (B) has a tensile strength of 200 kPa or more at 25 ℃, LNG storage tank. The method of claim 1,
Between the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B), further comprising a reinforcing layer, LNG storage tank. The method of claim 1,
Between the flexible polyurethane foam layer (A) and the rigid polyurethane foam layer (B), the LNG storage tank further comprising a high elongation polyurethane layer (C2) having an elongation of 300% or more at 25°C. The method of claim 1,
The rigid polyurethane foam layer (B) is that at least one reinforcing layer is inserted, the LNG storage tank. The method of claim 1,
The high elongation polyurethane layer (C1) contains a reinforcement material, LNG storage tank. The method of claim 1,
The ratio of the thickness of the flexible polyurethane foam layer (A), the rigid polyurethane foam layer (B) and the high elongation polyurethane layer (C1) is 10 to 100: 100 to 400: 1 to 10, LNG storage tank. The method of claim 1,
Arranged on the outer surface of the high elongation polyurethane layer (C1), further comprising a UV denaturation prevention layer, LNG storage tank

Images