KR20210157232A - Insulation structure of tank for storing liquefied gas - Google Patents

Abstract

Disclosed is a thermal insulation structure of a liquefied gas storage tank for ships having excellent thermal insulation performance. According to an embodiment of the present invention, a thermal insulation structure of a liquefied gas storage tank comprises: an insulation layer formed on a body of a tank for a ship for storing liquefied gas; a non-combustible layer coated on an outer surface of the insulation layer; and a protective layer formed on the non-combustible layer and protecting the insulation layer and the non-combustible layer.

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 ships for storing liquefied gas, and a non-combustible layer laminated on the outer surface of the heat-insulating layer to prevent penetration of the foam gas and external gas of the heat-insulating layer; A thermal insulation structure of the liquefied gas storage tank including a protective layer laminated on the outer surface of the non-combustible layer to protect the upper insulation layer may be provided.

The non-combustible layer includes an aluminum foil having a kraft paper attached to one surface facing the protective layer.

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.

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 40 .

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, for example, store a liquid fuel such as crude oil, or 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 40 is to store liquefied gas. The liquefied gas storage tank 40 may store liquefied natural gas as liquefied gas. However, the present embodiment is not limited thereto. The liquefied gas storage tank 40 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 40 may be installed on the deck of the hull 11 . That is, the liquefied gas storage tank 40 may be disposed above the fuel tank 20 on the hull 11 . The liquefied gas storage tank 40 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 40 is implemented as an IMO C type will be exemplarily described. When the liquefied gas storage tank 40 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 40 may store the liquefied gas at a pressure higher than that of the fuel tank 20 . The liquefied gas storage tank 40 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 40 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 to the main engine 22 as fuel, it is also possible to collect BOG (Boiled Off Gas) generated in the liquefied gas storage tank 40 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.

Referring to FIG. 5 , the heat insulating structure of the liquefied gas storage tank 40 may include an adhesive layer 42 , a heat insulating layer 43 , a non-combustible layer 44 , and a protective layer 45 .

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 is to be constructed on the adhesive layer 42 . The heat insulating layer 43 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 minimum 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 layer 43 is formed by using the spray polyurethane foam as a material, it may have advantages such as economic feasibility and construction convenience. In addition, when the heat insulating layer 43 is formed by 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, 300 mm according to the insulation requirements Or it may be designed to have a higher insulating thickness.

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 heat insulating layer 43 can be constructed so that the construction thickness is 15 mm or more during one-time construction. Preferably, the heat insulation layer 43 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 layer 43 may be installed 3 to 5 times per day, respectively.

On the other hand, the heat insulation layer 43 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 20 mm to 50 mm of the total insulation thickness.

The heat insulating layer 43 may be formed thicker than the non-combustible portion 44 on the tank body 41 in order to increase the heat insulating performance. The heat insulating layer 43 may be formed to be thicker than the adhesive layer 42 and the protective layer 45 .

The heat insulating layer 43 may include a foaming agent (hereinafter, referred to as a first foaming agent) having heat insulation performance. In this case, the heat insulating layer 43 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 heat insulating 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 layer 43 is formed of a 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 formula of each material.

The heat insulating layer 43 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 heat insulation layer 43 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. Standards for the fire resistance properties of the heat insulating layer 43 are generally required at least B2 or more according to the classification defined in DIN 4201-1.

However, since there are frequent cases in which the heat insulation layer 43 is damaged or the liquefied gas storage tank 40 on which the heat insulation layer 43 is constructed is damaged due to a fire occurring during the construction of a ship, recently B1, B2 The market demand for non-flammability beyond the flame-retardant grade of

The flame retardant properties of the heat insulating layer 43 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, a heat insulating layer 43 is constructed on the liquefied gas storage tank 40 to have heat insulation performance, and then a non-combustible layer 44 is formed on the heat insulation layer 43 to additionally have non-combustible performance. can be constructed.

The non-combustible layer 44 has reinforced non-combustible performance. The non-combustible layer 44 may be formed of a non-combustible material having a non-combustible property. Non-combustible materials include materials whose temperature does not rise above 50 degrees when heated at 750 degrees for 20 minutes, and there is no residual flame for more than 30 seconds after heating at 305 degrees for 10 minutes.

Mineral wool, glass wool, etc. can be used as such non-combustible materials, but in this embodiment, Duitex (product name), which is a mixture of airgel powder and ceramic, which is a nano-structure with excellent workability and non-combustibility, can be used, However, the present invention is not limited thereto. The non-combustible layer 44 made of the airgel and ceramic mixed layer has a low thermal conductivity (0.022 ~ 0.025 W/m.k) to provide non-combustibility and heat insulation to block the transfer of flames in case of fire.

The non-combustible layer 44 to be installed on the outer surface of the heat insulating layer 43 may be a Mineral Wool + Al Foil construction method or a Mineral Wool + Binder construction method may be used, but the non-combustible layer 44 of this embodiment is the insulating layer 43 It can be coated on the outer surface by spraying. The non-combustible layer 44 formed by the coating method has excellent workability and may improve visibility due to a reduction in the overall thickness of the liquefied gas storage tank 40 .

The non-combustible layer 44 may be constructed to have a thickness of about 20 mm to 30 mm when sprayed once, similarly to the heat insulating layer 43 . The incombustible layer 44 may be constructed to have one layer or two layers on the heat insulating layer 43 . Here, one layer refers to a layer formed with a thickness of 20mm to 30mm when spraying once.

The non-combustible layer 44 may be formed thinner than the heat insulating layer 43 . The incombustible layer 44 may be formed to be thicker than the adhesive layer 42 and the protective layer 45 .

The protective layer 45 is a surface protection layer and may be installed on the non-combustible layer 44 . This protective layer 45 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 this, it may be installed on the non-combustible layer 44 .

The protective layer 45 may be formed to have a thickness thinner than that of the heat insulating layer 43 and the non-combustible layer 44 , and may be applied in the form of a coating on the outer surface of the non-combustible layer 44 .

The protective layer 45 may be formed using 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 45 may be formed using polyurea such as urea resin, fiber reinforced plastics (FRP) resin, or the like as a material.

On the other hand, the heat insulation layer 43 may further include a second foaming agent having a lower boiling point than the first foaming agent in addition to the first foaming agent having heat insulation performance.

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 insulation layer 43 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 insulation layer 43 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 layer 43, 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 layer 43 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 at a higher ratio than the first foaming agent when the construction temperature is less than 0° C. can be mixed with

The heat insulating layer 43 may have sufficient mechanical properties even under low construction temperature conditions, such as winter, by applying a spray polyurethane foam having a low boiling point, rather than a single component spray polyurethane foam, as described above.

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, 40: liquefied gas storage tank;
41: tank body, 42: adhesive layer,
43: heat insulating layer, 44: non-combustible layer,
45: protective layer.

Claims (3)

Insulation layer formed on the body of the tank for ships for storing liquefied gas;
a non-combustible layer coated on the outer surface of the heat insulating layer;
Formed on the incombustible layer, the insulating layer and the protective layer for protecting the incombustible layer; insulation structure of the liquefied gas storage tank comprising a. According to claim 1,
The non-combustible layer is an insulating structure of a liquefied gas storage tank formed by spraying a non-combustible material (Duitex) mixed with airgel powder and ceramic. 3. The method of claim 2,
The non-combustible layer has a thermal conductivity (0.022 ~ 0.025 W / mk), and has a relatively larger thickness than the protective layer insulated structure of the liquefied gas storage tank.

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