KR20210157655A - Insulation structure of tank for storing liquefied gas - Google Patents

Abstract

An insulating structure of a liquefied gas storage tank is disclosed. The insulating structure of a liquefied gas storage tank according to an embodiment of the present invention comprises: a heat insulating layer formed on a body of a tank for ships for storing liquefied gas; a gas impermeable layer laminated on the outer surface of the heat insulating layer and preventing the permeation of a foam gas and an external gas of the heat insulating layer; and a protective layer laminated on the outer surface of the gas impermeable layer to protect the heat insulating layer. Embodiments of the present invention are to provide the insulating structure of a liquefied gas storage tank for ships with excellent insulation performance.

Description

Insulation structure of tank for storing liquefied gas

The present invention relates to an insulating structure of a liquefied gas storage tank for storing liquefied gas. More specifically, it relates to a thermal insulation structure of a liquefied gas storage tank installed on a ship.

As the International Maritime Organization (IMO)'s regulations on the emission of greenhouse gases and various air pollutants have been strengthened, the shipbuilding and shipping industry has recently replaced the existing fuels such as heavy oil and diesel oil, which are clean energy sources. Natural gas (NG) is widely used as fuel gas for ships.

Natural gas has methane as its main component, and is usually stored in a storage tank as liquefied gas (LNG), whose volume is reduced to about 1/600.

Korean Patent Publication No. 10-2019-0036222 (published on April 4, 2019)

Embodiments of the present invention are to provide a thermal insulation structure of a liquefied gas storage tank for ships with excellent thermal insulation performance.

According to one aspect of the present invention, a heat insulating layer formed on the body of a tank for a vessel for storing liquefied gas, and a gas impermeable layer laminated on the outer surface of the heat insulating layer and preventing the penetration of the foam gas and external gas of the heat insulating layer; , A heat insulating structure of the liquefied gas storage tank including a protective layer laminated on the outer surface of the gas impermeable layer to protect the heat insulating layer may be provided.

The gas impermeable layer may include an aluminum foil, and may be adhered to the protective layer.

The gas impermeable layer may include an aluminum foil to which kraft paper is pre-attached to one surface, and the other surface may be adhesively fixed to the outer surface of the insulating layer, and the protective layer may be non-adhesive to the outer surface of the kraft paper.

The heat insulating layer is formed on the outer surface of the body and is formed on the first heat insulating part, the first insulating part comprising a first foaming agent having thermal insulation performance and a second foaming agent having a lower boiling point than that of the first foaming agent; and a second heat insulating portion including the first foaming agent.

The heat-insulating layer is formed on the outer surface of the body and includes a heat-insulating portion comprising a component having heat-insulating performance, and a flame-retardant section formed on the heat-insulating section and comprising a component having heat-insulating performance and a flame-retardant component .

Embodiments of the present invention can prevent the deterioration of the thermal insulation performance of the liquefied gas storage tank over time.

1 is a diagram schematically illustrating an internal structure of a ship according to an embodiment.
2 is a view showing a schematic structure of a liquefied gas storage tank according to an embodiment of the present invention.
3 is a first exemplary view showing various embodiments of a liquefied gas storage tank according to an embodiment of the present invention.
4 is a second exemplary view showing various embodiments of a liquefied gas storage tank according to an embodiment of the present invention.
5 is a view for explaining the insulation structure of the liquefied gas storage tank according to an embodiment of the present invention.
6 is a view for explaining the insulation structure of the liquefied gas storage tank according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided as examples in order to sufficiently convey the spirit of the present invention to those of ordinary skill in the art to which the present invention pertains. The present invention is not limited to the embodiments described below and may be embodied in other forms. In order to clearly explain the present invention, parts irrelevant to the description are omitted from the drawings, and in the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. Like reference numerals refer to like elements throughout.

1 is a diagram schematically illustrating an internal structure of a ship according to an embodiment.

According to FIG. 1 , a ship 10 may include a hull 11 , a fuel tank 20 , a propulsion equipment 21 , a load equipment 23 , and a liquefied gas storage tank 30 .

The ship 10 is floating on the sea, and is to operate the sea. The vessel 10 may be implemented as an LNG-propelled vessel using liquefied natural gas (LNG) as a fuel.

The vessel 10 may be implemented as a vessel that transports people or cargo to a destination on the sea. The vessel 10 may be implemented as, for example, a passenger ship, a cargo carrier, a crude oil carrier, a container ship, etc. It is possible.

However, the present embodiment is not limited thereto. The ship 10 may also be implemented as an offshore structure (or off-shore plant) built on the sea to develop marine resources such as crude oil and natural gas. The vessel 10 may be implemented as, for example, a Floating, Storage and Regasification Unit (FSRU), Floating, Production, Storage and Offloading (FPSO), Floating LNG (FLNG), or the like.

The hull 11 is to constitute the body of the ship 10 having a deck (deck) on the upper portion. The hull 11 may include a fuel tank 20 , propulsion equipment 21 , load equipment 23 , and the like therein.

The fuel tank 20 is to store fuel used to produce a main power source. The fuel tank 20 may store, for example, liquefied natural gas (LNG). However, the present embodiment is not limited thereto. The fuel tank 20 may store, for example, a liquid fuel such as crude oil, or may store a gaseous fuel such as hydrogen.

At least one fuel tank 20 may be installed in the inner space of the hull 11 . When a plurality of fuel tanks 20 are installed in the inner space of the hull 11 , the plurality of fuel tanks 20 may be sequentially disposed in the longitudinal direction of the hull 11 . However, the present embodiment is not limited thereto. The plurality of fuel tanks 20 may be sequentially disposed in the width direction of the hull 11 , and may be randomly disposed regardless of the longitudinal direction or the width direction of the hull 11 .

On the other hand, when a plurality of fuel tanks 20 are installed on the hull 11 , some may be installed in the inner space of the hull 11 , and some may be installed on the deck. It is also possible that some store liquefied natural gas, and some store liquid fuels such as crude oil or gaseous fuels such as hydrogen.

The propulsion equipment 21 is to generate propulsion so that the navigation of the hull 11 is possible. The propulsion equipment 21 may generate propulsion by using the fuel stored in the fuel tank 20 . The propulsion equipment 21 may be configured to include a main engine 22 to generate propulsion force.

The main engine 22 may include any one of a low pressure gas injection engine, a medium pressure gas injection engine, and a high pressure gas injection engine. The low-pressure gas injection engine uses fuel gas of about 5 bar to 7 bar, and may include a DFDE (Dual Fuel Diesel Electric) engine or the like. Such a low-pressure gas injection engine may be implemented as a dual fuel engine capable of using not only natural gas but also heavy fuel oil (HFO) as fuel. The medium pressure gas injection engine uses fuel gas of about 16 bar to 45 bar. The high-pressure gas injection engine uses fuel gas of approximately 150 bar to 300 bar, and may include an M-type Electronically Controlled Gas Injection (ME-GI) engine.

A device for adjusting the temperature, pressure, state, etc. of the fluid to match the fuel gas supply condition of the main engine 22 may be included in the processing unit (not shown). When the main engine 22 is, for example, a low-pressure gas injection engine, a carburetor for vaporizing the fluid, a pressure valve for regulating the fluid passing through the carburetor to the fuel gas supply pressure of the low-pressure gas injection engine, and a low pressure for the fluid passing through the pressure valve A heater for correcting a temperature according to a required temperature of the gas injection engine may be included in the processing unit. When the main engine 22 is, for example, a medium-pressure gas injection engine, a control valve for regulating the pressure of the fluid, a heater, and the like may be included in the processing unit. When the main engine 22 is, for example, a high-pressure gas injection engine, a high-pressure pump that pressurizes the fluid according to the fuel gas supply pressure of the high-pressure gas injection engine, a high-pressure vaporizer that vaporizes the pressurized fluid, etc. may be included in the processing unit. have.

The load equipment 23 is for onboard maintenance. The load equipment 23 may be provided inside or on the deck of the hull 11 for this purpose, and a pump for drainage equipment, a pump for fuel supply, a blower, an air conditioner, a light, a GPS receiver, a radar device, a ship It may include an automatic identification device, a magnetic compass, a wireless device, a ship location transmitter, and the like.

Meanwhile, the hull 11 may include a generator engine 24 to supply power so that the load equipment 23 can operate smoothly.

Meanwhile, the vessel 10 may be implemented as a hybrid vessel equipped with both a main power source and an auxiliary power source. In this case, the fuel stored in the fuel tank 20 may be used to produce a main power source, a battery room in which a plurality of battery modules are mounted, a plurality of fuel cells, a plurality of A solar panel or the like may be used to produce an auxiliary power source.

When the vessel 10 is implemented as a hybrid vessel, a main power source may be used to operate the propulsion equipment 21 and an auxiliary power source may be used to operate the load equipment 23 . However, the present embodiment is not limited thereto. The vessel 10 uses both a main power source and an auxiliary power source to operate the propulsion equipment 21 , and it is also possible to use an auxiliary power source to operate the load equipment 23 .

On the other hand, it is also possible for the vessel 10 to selectively use the main power source and the auxiliary power source to operate the propulsion equipment 21 and the load equipment 23 . The vessel 10 uses, for example, one of a main power source and an auxiliary power source to operate the propulsion equipment 21 , and the other power source to operate the load equipment 23 . circles are available.

The liquefied gas storage tank 30 is to store liquefied gas. The liquefied gas storage tank 30 may store liquefied natural gas as liquefied gas. However, the present embodiment is not limited thereto. The liquefied gas storage tank 30 can also store liquefied ethane, liquefied ethylene, liquefied petroleum gas, liquefied propane, liquefied butane, etc. as liquefied gas.

At least one liquefied gas storage tank 30 may be installed on the deck of the hull 11 . That is, the liquefied gas storage tank 30 may be disposed above the fuel tank 20 on the hull 11 . The liquefied gas storage tank 30 is, for example, an International Maritime Organization (IMO) type A (Type A) tank, a B type (Type B) tank, a C type (Type C) independent tank, etc. can be implemented. Hereinafter, a case in which the liquefied gas storage tank 30 is implemented as an IMO C type will be exemplarily described. When the liquefied gas storage tank 30 is implemented as an IMO C type, it may be implemented in a cylindrical shape, for example, as shown in FIG. 2 . 2 is a view showing a schematic structure of a liquefied gas storage tank according to an embodiment of the present invention.

The liquefied gas storage tank 30 may store the liquefied gas at a higher pressure than the fuel tank 20 . The liquefied gas storage tank 30 may store the same liquefied gas as that stored in the fuel tank 20 , but it is also possible to store a different liquefied gas than that stored in the fuel tank 20 .

When the liquefied gas storage tank 30 stores the same liquefied gas (eg, liquefied natural gas) as that stored in the fuel tank 20 , the liquefied gas may be used as a fuel as shown in FIG. 3 . It can be supplied to the fuel tank 20 so that, as shown in FIG. 4 , it is also possible to directly supply the liquefied gas as fuel to the main engine 22 . When the liquefied gas is directly supplied as fuel to the main engine 22 , it is also possible to collect BOG (Boiled Off Gas) generated in the liquefied gas storage tank 30 and supply it to the main engine 22 . 3 is a first exemplary view showing various embodiments of a liquefied gas storage tank according to an embodiment of the present invention, and FIG. 4 is a second exemplary view showing various embodiments of a liquefied gas storage tank according to an embodiment of the present invention. It is an example diagram.

5 is a view for explaining the insulation structure of the liquefied gas storage tank according to an embodiment of the present invention.

The liquefied gas storage tank 30 may have an outer surface insulated. For this purpose, the liquefied gas storage tank 30 has two spray polyurethane foam (SPF) layers, that is, the first SPF layer having sufficient mechanical properties even at low temperature conditions by having a foaming gas with a low boiling point, and thermal insulation performance This superior second SPF layer may be included as an insulating structure.

The heat insulating structure of the liquefied gas storage tank 30 includes an adhesive layer 32 , a heat insulating layer 33 , a gas impermeable layer 36 , and a protective layer 37 .

The adhesive layer 32 is to be installed on the tank body 31 . The adhesive layer 32 may be constructed to increase adhesion between the surface of the tank body 31 and the heat insulating layer 33 , and may be formed using a paint (eg, a primer) as a material.

Meanwhile, the adhesive layer 32 may be installed on the tank body 31 after a tank surface cleaning check is performed on the surface of the tank body 31 .

The heat insulating layer 33 includes a first heat insulating part 34 and a second heat insulating part 35 .

The first heat insulating part 34 is constructed on the adhesive layer 32 . This first heat insulating part 34 may be formed using spray polyurethane foam (SPF) as a material, and in particular, has a low boiling point foaming gas, and is made of spray polyurethane foam having sufficient mechanical properties even under low temperature conditions. can be formed by

When the first heat insulating part 34 is formed using spray polyurethane foam as a material, it may have advantages such as economic feasibility and construction convenience. When the first heat insulating part 34 is formed using spray polyurethane foam as a material, it may have a multi-layered structure due to construction characteristics, and may be designed to have a thickness of at least 13 mm and an insulating thickness of 300 mm or more.

Meanwhile, as described above, the liquefied gas storage tank 30 may be implemented as a C-type LNG storage tank in this embodiment. Since the C-type LNG storage tank shows a temperature difference of up to 208℃ (upper limit 45℃, lower limit 163℃) before and after loading LNG, it must be designed to respond to contraction and expansion.

However, the above contraction and expansion may occur simultaneously in the radial direction as well as the longitudinal direction of the LNG storage tank. Therefore, it is preferable that the first heat insulating part 34 is designed so as not to cause quality problems such as cracks in consideration of this point.

The first insulator 34 is required to have minimum mechanical properties capable of withstanding thermal stress resulting from a temperature difference of up to 208° C. as well as thermal insulation performance. However, the mechanical properties of polyurethane foam may vary depending on many factors such as temperature, humidity, and thickness of construction.

When the first heat insulating part 34 is formed using spray polyurethane foam as a material, if the surface temperature of the tank body 31 is too low, the first heat insulating part 34 cannot obtain sufficient mechanical properties, so cracks, Quality problems such as peeling may occur. Therefore, when the first heat insulating part 34 is constructed using spray polyurethane foam as a material on the adhesive layer 32 , the surface temperature of the tank body 31 is 10° C. as the construction temperature of the first heat insulating part 34 . More than that is suitable.

However, in winter, it is difficult to maintain the surface temperature of the tank body 31 at 10 ° C. or higher, and the lower the surface temperature of the tank body 31, the lower the thermal insulation performance and mechanical properties of the spray polyurethane foam, so spray polyurethane A situation in which it becomes impossible to construct the first heat insulating part 34 by using the foam as a material may occur frequently.

The need for a construction temperature condition of 10℃ or higher is due to the material properties of the spray polyurethane foam. Spray polyurethane foam is a spray-type polyurethane foam. MDI (Methylene Di-para-phenylene Isocyanate) and polyol are the main materials, and a foaming agent, a catalyst, a foam stabilizer, and a functional additive are mixed. It is a foamed product that can be obtained by reacting. The constraint on the construction temperature as described above can be found in the construction temperature of the foaming agent.

As a foaming agent satisfying thermal insulation performance, a foaming agent having a boiling point of about 15.3° C. (Chemical formula CF3CH2CHF2, foaming agent HFC-245fa) is widely used. The spray polyurethane foam manages the surface temperature of the tank body 31 at which a smooth mixing reaction can occur by using the foaming agent described above at about 10°C.

Therefore, in this embodiment, by adding a foaming agent having a lower boiling point than the foaming agent in addition to the foaming agent in the spray polyurethane foam, the first heat insulating part 34 is configured to have sufficient mechanical properties even in low temperature conditions can do.

In summary, the first heat insulating part 34 may be formed of spray polyurethane foam as a material, and in this case, the first heat insulating part 34 has a first foaming agent having heat insulation performance and a boiling point of the first foaming agent. A low second blowing agent may further be included.

The first foaming agent may be a foaming agent having a boiling point of 10°C to 40°C while having thermal insulation performance. As described above, the first blowing agent may be, for example, a blowing agent having a boiling point of about 15.3° C. (Formula CF3CH2CHF2, blowing agent HFC-245fa). However, the present embodiment is not limited thereto. The first blowing agent may be a blowing agent having a boiling point of 15° C. to 32° C. (eg, HBA-2), a blowing agent having a boiling point of 15° C. to 30° C. (eg, AFA-L1), and the like.

The second blowing agent may be a blowing gas having a lower saturation temperature (or boiling point) than the first blowing agent. This second blowing agent may be a blowing gas having a saturation temperature of sub-zero. The second blowing agent may be, for example, a blowing agent having a boiling point of -139°C (formula CO2, blowing agent CO2), a blowing agent having a boiling point of -40°C (chlorodifluoromethane, chemical formula CHCIF2, blowing agent HFC-22), and the like.

When the first heat insulating part 34 is formed by using the spray polyurethane foam as a material, the first foaming agent may be mixed in a higher ratio than the second foaming agent. The first heat insulating part 34 may mix the first foaming agent in a higher ratio than the second foaming agent, for example, when the construction temperature exceeds 0°C. However, the present embodiment is not limited thereto. In the first heat insulating part 34, it is also possible to mix the first foaming agent and the second foaming agent in the same ratio, or it is also possible to mix the second foaming agent in a higher ratio than the first foaming agent. The first heat insulator 34 may, for example, mix the first foaming agent and the second foaming agent in the same ratio when the construction temperature is 0°C, and use the second foaming agent than the first foaming agent when the construction temperature is less than 0°C. Higher proportions can be mixed.

As described above, the first heat insulating part 34 is not a single component spray polyurethane foam, but a spray polyurethane foam having a low boiling point foaming gas to have sufficient mechanical properties even under low construction temperature conditions such as winter season. can

Meanwhile, the first heat insulating part 34 may be formed to be thicker than the adhesive layer 32 on the tank body 31 .

The second heat insulating part 35 is constructed on the first heat insulating part 34 . The second heat insulating part 35 may be formed using spray polyurethane foam as a material, similar to the first heat insulating part 34 , and may be formed to be thicker than the first heat insulating part 34 in order to increase thermal insulation performance. . On the other hand, the second heat insulating portion 35 may be formed by using a spray polyurethane foam excellent in heat insulating performance as a material.

The second heat insulating part 35 is formed on the first heat insulating part 34 . That is, the second heat insulating portion 35 is formed in the outer layer, which is not greatly affected by the construction temperature. Accordingly, the second heat insulating part 35 may include only the first foaming agent having heat insulating performance. The second heat insulating part 35 may be composed of, for example, a spray polyurethane foam containing a foaming gas such as HFC-245fa having excellent thermal insulation performance, which is not relatively sensitive to the construction temperature.

However, the present embodiment is not limited thereto. Like the first heat insulating part 34 , the second heat insulating part 35 may be formed to have sufficient mechanical properties even under a low temperature condition. In this case, the second heat insulating part 35 may include a first foaming agent having heat insulation performance and a second foaming agent having a lower boiling point than the first foaming agent.

The performance of spray polyurethane foam is affected by the thickness of the application as well as temperature and humidity. If the construction thickness is 13 mm or less during one-time construction, thermal and mechanical properties may be deteriorated. Therefore, in this embodiment, the first heat insulating part 34 and the second heat insulating part 35 can be constructed so that the construction thickness is 15 mm or more during one-time construction. Preferably, the first heat insulating part 34 and the second heat insulating part 35 may be constructed so that the construction thickness is 20 mm to 30 mm during one-time construction.

On the other hand, so that the heat generated inside the spray polyurethane foam after construction can be sufficiently cooled, the construction thickness that can be installed per day may be limited to about 100 mm. In this case, the first heat insulating part 34 and the second heat insulating part 35 may be respectively installed 3 to 5 times per day.

The gas impermeable layer 36 may be installed on the second heat insulating part 35 . The gas impermeable layer 36 blocks the blowing gas foamed in the heat insulating layer 33 from being replaced with an external gas (air or nitrogen). That is, the gas impermeable layer 36 may be formed of a material through which a foaming gas or an external gas cannot permeate.

Specifically, the spray polyurethane foam installed on the heat insulating layer naturally deteriorates as the foaming gas, which has relatively excellent heat insulating performance, is replaced by mass transfer according to the concentration gradient with the external gas over time. That is, the spray polyurethane foam is inversely proportional to the square of the thickness of the heat insulating layer 33, and has a characteristic proportional to time. Although the performance degradation of up to 40% occurs depending on the foaming gas and the elapsed time, it is possible to improve the deterioration of the insulation performance as time passes by the gas impermeable layer 36 being constructed on the second insulation part 35. can

The gas impermeable layer 36 may include aluminum foil and may be adhered to the second heat insulating part 35 .

When one surface of the gas impermeable layer 36 is adhered to the gas impermeable layer 36 , Kraft Paper may be adhered to the other surface opposite to the one surface.

The gas impermeable layer 36 may be installed on the second heat insulating part 35 after kraft paper is first attached to one surface of the aluminum foil.

The protective layer 37 is a surface protection layer and may be applied on the gas impermeable layer 36 . The protective layer 37 may be installed on the gas impermeable layer 36 to protect the first heat insulating part 34 and the second heat insulating part 35 from external impact or moisture.

The protective layer 37 may be formed to have a thickness smaller than that of the first heat insulating part 34 and the second heat insulating part 35 . The protective layer 37 may be formed of a material such as polyurea such as urea resin, fiber reinforced plastic (FRP) resin, glass-fiber reinforced plastics (GRP) resin, etc. and may be constructed in the form of a coating on the outer surface of the gas impermeable layer 36 .

The protective layer 37 may be adhered to the gas impermeable layer 36 , and may be constructed in a non-adhesive manner when kraft paper is adhered to the outer surface of the gas impermeable layer 36 .

When the protective layer 37 is constructed in a non-adhesive manner on the gas impermeable layer 36 , the protective layer 37 is damaged by relieving the stress applied to the protective layer 37 even by thermal deformation of the heat insulating layer 33 . can prevent

6 is a view for explaining the insulation structure of the liquefied gas storage tank according to another embodiment of the present invention.

Referring to FIG. 6 , the heat insulating structure of the liquefied gas storage tank 40 may include an adhesive layer 42 , a heat insulating layer 43 , a gas impermeable layer 46 , and a protective layer 47 .

The adhesive layer 42 is to be installed on the tank body 41 . The adhesive layer 42 may be constructed to increase adhesion between the surface of the tank body 41 and the heat insulating layer 43 , and may be formed using a paint (eg, a primer) as a material.

Meanwhile, the adhesive layer 42 may be installed on the tank body 41 after a tank surface cleaning check is performed on the surface of the tank body 41 .

The heat insulating layer 43 includes a heat insulating part 44 and a heat-resistant part 45 .

The heat insulating part 44 is constructed on the adhesive layer 42 . The heat insulating part 44 may be formed using spray polyurethane foam (SPF) as a material, and in particular, it may be formed using spray polyurethane foam optimized for heat insulation while having minimal mechanical properties.

Spray polyurethane foam is a polyurethane foam (polyurethane foam) of the spray type (spray type). This spray polyurethane foam consists of an isocyanate compound (eg, Methylene Di-para-phenylene Isocyanate (MDI)) and a polyol compound having a hydroxyl group, and a foaming agent, a flame retardant, a catalyst, and a crosslinking agent in the polyol compound. and the like may be mixed and reacted to form a foamed product.

When the heat insulating portion 44 is formed using spray polyurethane foam as a material, it may have advantages such as economic feasibility and construction convenience. In addition, when the heat insulating portion 44 is formed using spray polyurethane foam as a material, it may have a layered structure due to the nature of construction, and is constructed to have a thickness of about 20 mm to 30 mm at one time of spraying, depending on the insulation requirements. It can be designed to have an insulation thickness of 300mm or more.

The performance of spray polyurethane foam is affected by the thickness of the application as well as temperature and humidity. If the construction thickness is 13 mm or less during one-time construction, thermal and mechanical properties may be deteriorated. Therefore, in the present embodiment, the heat insulating portion 44 can be constructed so that the construction thickness is 15 mm or more during one-time construction. Preferably, the heat insulating portion 44 may be constructed so that the construction thickness is 20 mm to 30 mm during one-time construction.

On the other hand, so that the heat generated inside the spray polyurethane foam after construction can be sufficiently cooled, the construction thickness that can be installed per day may be limited to about 100 mm. In this case, the heat insulating part 44 may be installed 3 to 5 times per day, respectively.

On the other hand, the heat insulation portion 44 may be pre-constructed from the surface of the tank body 41 by a predetermined thickness for the purpose of heat insulation, and in this case, it may be constructed except for 20mm to 50mm of the total insulation thickness.

The heat insulating part 44 may be formed to be thicker than the flame retardant part 45 on the tank body 41 in order to increase thermal insulation performance. The heat insulating portion 44 may be formed to be thicker than the adhesive layer 42 and the protective layer 47 .

The heat insulating part 44 may include a foaming agent (hereinafter, referred to as a first foaming agent) having heat insulation performance. In this case, the heat insulating portion 44 may be composed of, for example, a spray polyurethane foam containing a foaming gas such as HFC-245fa, which is not relatively sensitive to the construction temperature and has excellent thermal insulation performance.

The first foaming agent may be a foaming agent having a thermal insulation performance and a boiling point of 10°C to 40°C. The first blowing agent may be, for example, a blowing agent having a boiling point of about 15.3°C (formula CF3CH2CHF2, blowing agent HFC-245fa). However, the present embodiment is not limited thereto. The first blowing agent may be a blowing agent having a boiling point of 15° C. to 32° C. (eg, HBA-2), a blowing agent having a boiling point of 15° C. to 30° C. (eg, AFA-L1), and the like.

On the other hand, when the heat insulating portion 44 is formed by using the spray polyurethane foam as a material, various physical properties such as thermal properties, mechanical properties, and other flame retardant properties may vary depending on the formulation of each material.

The heat insulating part 44 basically needs heat insulating performance and mechanical properties. In the above, the thermal insulation performance is required to minimize the vaporization of the liquefied gas stored in the liquefied gas storage tank (40). In addition, mechanical properties are required to withstand thermal stress generated in the tank body 41 due to a temperature difference (up to 208 degrees) between the tank body 41 as the outside air and the liquefied gas as the cargo.

On the other hand, the insulation 44 may be required to have fire resistance in consideration of the occurrence of a fire in a ship according to the IGC code and each classification rule. The standard for the fire resistance properties of the insulating part 44 is generally required to be at least B2 or more according to the classification defined in DIN 4201-1.

However, since there are frequent cases in which the thermal insulation part 44 is damaged or the liquefied gas storage tank 40 in which the thermal insulation part 44 is constructed is damaged due to a fire occurring during the construction of a ship, recently B1 The market demand for more flame retardant performance is gradually increasing.

The flame-retardant properties of the heat insulating portion 44 can be improved by increasing the amount of the flame-retardant additive. However, if the flame retardant additive component is increased in the spray polyurethane foam, there is a problem in that the thermal and mechanical properties of the spray polyurethane foam are rapidly reduced.

In order to solve this problem, first, the insulating part 44 is constructed on the liquefied gas storage tank 40 to have thermal insulation performance, and then the flame retardant part 45 on the insulating part 44 to additionally have flame retardant performance. ) can be constructed.

The flame-retardant part 45 is a thing of which flame-retardant performance is reinforced. This flame-retardant part 45 may be constructed on the heat insulating part 44 , and similarly to the heat insulating part 44 may be formed by using spray polyurethane foam as a material.

The flame-retardant part 45 may add a flame retardant to enhance flame-retardant performance. The flame-retardant part 45 may include at least one component among brominated flame retardants (BFRs) (or halogen-based flame retardants), phosphorus-based flame retardants, inorganic flame retardants, and the like as flame retardant additives. Meanwhile, the flame retardant additive may be in the form of a powder, but is not necessarily limited thereto.

When the flame retardant part 45 includes a brominated flame retardant as a flame retardant additive, poly bromo biphenyls (PBBs; Poly Brominated Biphenyls), poly bromo diphenyl ethers (PBDEs; Poly Bromo Diphenyl Ethers), tetrabromobisphenol A (TBBP A; Tetra Bromobis Phenol A), Deca-BDE; Deca Bromo Diphenyl Ether), Hexa Bromo Cyclo Dodecane (HBCD; Hexa Bromo Cyclo Dodecane), Tribromophenol (TBP; Tri Bromo Phenol) and the like may include at least one component.

When the flame retardant portion 45 includes a phosphorus-based flame retardant as a flame retardant additive, triphenyl phosphate (TPP; Tri Phenyl Phosphate), tri aryl phosphate (TAP; Tri Aryl Phosphate), tri cresyl phosphate (TCP; Tri Cresyl Phosphate), At least one component of chloro ethyl phosphate (CEP; Chloro Ethyl Phosphate), a halogen-containing condensed phosphoric acid ester, and the like may be included.

When the flame retardant part 45 includes an inorganic flame retardant as a flame retardant additive, antimony trioxide (Sb2O3), aluminum hydroxide (Al(OH)3), magnesium hydroxide (magnesium hydroxide, Mg(OH)2) , calcium carbonate (CaCO3), magnesium carbonate (MgHCO3), talc, etc. may include at least one component.

The flame-retardant portion 45 may include an appropriate amount of a flame-retardant additive to prevent deterioration of thermal and mechanical properties of the spray polyurethane foam while improving flame-retardant performance.

In the case of spray polyurethane foam, the mixing ratio of isocyanate (MDI) liquid and polyol liquid, which are the main materials, is preferably 100/110 by weight. In this embodiment, it may be necessary to add 10% or more (preferably 10% to 20%) of the flame retardant based on the weight of the main material in order to satisfy the B1 grade.

The flame-retardant portion 45 may be constructed to have a thickness of about 20 mm to 30 mm at the time of one injection, like the heat insulating portion 44 . The flame-retardant portion 45 may be constructed to have one layer or two layers on the heat insulating portion 44 . Here, one layer refers to a layer formed with a thickness of 20mm to 30mm when spraying once. The flame-retardant part 45 can improve the flame-retardant performance of the heat insulating structure constructed on the liquefied gas storage tank 40 through this.

The flame-retardant portion 45 may be formed thinner than the heat insulating portion 44 . The flame-retardant portion 45 may be formed to be thicker than the adhesive layer 42 and the protective layer 47 .

The gas impermeable layer 46 may be installed on the flame retardant portion 45 . The gas impermeable layer 46 blocks the foaming gas foamed in the heat insulating layer 43 from being substituted with an external gas (air or nitrogen). That is, the gas impermeable layer 46 may be formed of a material through which the foaming gas or external gas cannot permeate.

Specifically, the spray polyurethane foam installed on the heat insulating layer naturally deteriorates as the foaming gas, which has relatively excellent heat insulating performance, is replaced by mass transfer according to the concentration gradient with the external gas over time. That is, the spray polyurethane foam is inversely proportional to the square of the thickness of the heat insulating layer 43, and has a characteristic proportional to time. Performance degradation of up to 40% occurs depending on the foaming gas and the elapsed time, but it can be improved that the thermal insulation performance deteriorates over time by constructing the gas impermeable layer 46 on the flame-retardant portion 45 .

The gas impermeable layer 46 may include aluminum foil and may be adhered to the flame-retardant portion 45 .

When one surface of the gas impermeable layer 46 is adhered to the gas impermeable layer 46 , Kraft Paper may be adhered to the other surface opposite to the one surface.

The protective layer 47 is a surface protection layer and may be installed on the flame-retardant portion 45 . This protective layer 47 prevents the heat insulation layer 43 from being damaged from external impact, and rainwater, waves, moisture, etc., intrudes into the inside of the insulation layer 43 due to the nature of the liquefied gas storage tank 40 exposed to the outside air. In order to prevent it, it may be constructed on the flame-retardant portion 45 .

The protective layer 47 may be formed to have a thickness thinner than that of the heat insulating portion 44 and the flame-retardant portion 45 , and may be applied in the form of a coating on the outer surface of the flame-retardant portion 45 .

The protective layer 47 may be formed of a glass-fiber reinforced plastic (GRP) resin, a polymeric coating, or the like as a material. However, the present embodiment is not limited thereto. The protective layer 47 may be formed using polyurea such as urea resin, fiber reinforced plastic (FRP) resin, or the like as a material.

Meanwhile, in addition to the first foaming agent having thermal insulation performance, the heat insulating unit 44 may further include a second foaming agent having a lower boiling point than the first foaming agent.

The second blowing agent may be a blowing gas having a lower saturation temperature (or boiling point) than the first blowing agent. This second blowing agent may be a blowing gas having a saturation temperature of sub-zero. The second blowing agent may be, for example, a blowing agent having a boiling point of -139°C (formula CO2, blowing agent CO2), a blowing agent having a boiling point of -40°C (chlorodifluoromethane, chemical formula CHCIF2, blowing agent HFC-22), and the like.

When the heat insulating part 44 is formed by using the spray polyurethane foam as a material, the first foaming agent may be mixed in a higher ratio than the second foaming agent. The heat insulating part 44 may mix the first foaming agent in a higher ratio than the second foaming agent, for example, when the construction temperature exceeds 0°C. However, the present embodiment is not limited thereto. In the heat insulating part 44, it is also possible to mix the first foaming agent and the second foaming agent in the same ratio, or the second foaming agent in a higher ratio than the first foaming agent. The heat insulating unit 44 may, for example, mix the first foaming agent and the second foaming agent in the same ratio when the construction temperature is 0° C., and use the second foaming agent higher than the first foaming agent when the construction temperature is less than 0° C. It can be mixed in proportion.

As described above, the heat insulating part 44 is not a single component spray polyurethane foam, but a spray polyurethane foam having a low boiling point foaming gas, so that it can have sufficient mechanical properties even under low construction temperature conditions such as winter season. .

In the above, specific embodiments have been shown and described. However, it is not limited to the above-described embodiment, and a person of ordinary skill in the art to which the invention pertains will be able to make various changes without departing from the spirit of the invention described in the claims below.

10: ship, 11: hull,
20: fuel tank, 30, 40: liquefied gas storage tank;
31,41: tank body, 32,42: adhesive layer,
33, 43: a heat insulating layer, 34: a first heat insulating portion,
35: a second heat insulating part, 36, 46: a gas impermeable layer,
37, 47: a protective layer, 44: a heat insulating part,
45: heating part.

Claims (5)

Insulation layer formed on the body of the tank for ships for storing liquefied gas;
a gas impermeable layer laminated on the outer surface of the heat-insulating layer and preventing penetration of the foam gas and external gas of the heat-insulating layer;
Insulation structure of a liquefied gas storage tank comprising a; a protective layer laminated on the outer surface of the gas impermeable layer to protect the heat insulating layer. The method of claim 1,
The gas impermeable layer includes an aluminum foil, and the insulating structure of the liquefied gas storage tank is adhesively constructed on the protective layer. The method of claim 1,
The gas impermeable layer includes an aluminum foil to which kraft paper is pre-attached on one surface, and the other surface is adhesively fixed to the outer surface of the insulation layer, and the protective layer is non-adhesive to the outer surface of the kraft paper. Insulation structure of a liquefied gas storage tank. 4. The method according to any one of claims 1 to 3,
The heat insulating layer is formed on the outer surface of the body and is formed on a first heat insulating part comprising a first foaming agent having heat insulation performance and a second foaming agent having a lower boiling point than the first foaming agent, and the first heat insulating part, A thermal insulation structure of a liquefied gas storage tank including a second thermal insulation portion comprising a first foaming agent. 4. The method according to any one of claims 1 to 3,
The heat-insulating layer is formed on the outer surface of the body and comprises a heat-insulating part comprising a component having a heat-insulating performance, and a flame-retardant section formed on the heat-insulating section and comprising a component having a heat-insulating performance and a component having a flame-retardant performance Thermal insulation structure of liquefied gas storage tank.

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