Pressure vessels for LNG storage, vessels and offshore structures with them

Abstract

A pressure vessel for storing LNG, a ship having the same, and an offshore structure are disclosed. The pressure vessel for storing LNG according to the present invention is a pressure vessel for storing LNG, comprising: an inner shell that stores LNG inside and includes a plurality of layers including a graphene layer; an outer shell provided to surround the outer side of the inner shell; and an insulating layer provided between the inner shell and the outer shell, so as to be able to absorb deformation caused by the pressure of the LNG in the graphene layer of the inner shell.

Description

Technology Field

[0001] The present invention relates to a pressure vessel for LNG storage, a ship and an offshore structure having the same, and more specifically, to a pressure vessel for LNG storage that includes an inner shell comprising a plurality of layers including a graphene layer, an outer shell provided on the outside of the inner shell, and an insulating layer provided between the inner shell and the outer shell, capable of absorbing deformation caused by the pressure of LNG stored inside the vessel in the graphene layer of the inner shell, and a ship and an offshore structure having the same. Background Technology

[0002] Generally, liquefied natural gas (LNG) is a colorless, transparent, ultra-low temperature liquid obtained by cooling natural gas, which is mainly composed of methane, to an ultra-low temperature of -162°C at atmospheric pressure to reduce its volume to one-six hundredth of its original size. It is known to be economical for long-distance transportation because it has better transport efficiency than gaseous gas.

[0003] Liquefied natural gas (LNG) has been applied to large-scale, long-distance transportation to ensure economic feasibility, as the construction costs for production plants and vessels are high; in contrast, pipelines or Compressed Natural Gas (CNG) are known to be more economical for small-scale, short-distance transportation.

[0004] However, transport via pipelines is subject to geographical constraints and can cause environmental damage, and CNG has the disadvantage of low transport efficiency; therefore, it is often transported by vessels such as LNG carriers equipped with storage containers capable of loading cryogenic LNG at atmospheric pressure (1 bar).

[0005] Ships transporting liquefied natural gas are equipped with storage tanks capable of storing liquefied natural gas that has been cooled and liquefied. To safely store and store the liquefied natural gas at cryogenic temperatures, the cargo tanks can be made of materials capable of withstanding cryogenic temperatures, such as aluminum steel, stainless steel, and 35% nickel steel, and are designed with a structure that is resistant to thermal stress and thermal shrinkage and prevents heat intrusion.

[0006] Storage tanks can be classified into independent tanks and membrane types depending on whether the load of the cargo acts directly on the insulation. Representative membrane-type storage tanks include the GTT NO 96 and TGZ Mark III types, while representative independent-type storage tanks include the MOSS and IHI-SPB types.

[0007] The structure of an independent storage tank is described in Korean Patents No. 10-15063, No. 10-305513, No. 10-189306, etc.

[0008] Generally, freestanding storage tanks are constructed by attaching relatively rigid insulation panels, such as polyurethane, to a tank body made of aluminum alloy, and are placed on tank supports arranged on the inner floor of the hull. The problem to be solved

[0009] Among independent storage tanks, the pressure vessel is a storage tank designed to withstand a pressure rise caused by evaporated gas generated from the LNG stored inside the tank. An example of such a pressure vessel is schematically illustrated in Fig. 1.

[0010] As illustrated in FIG. 1, a pressure vessel (10) with a circular cross-section is placed on a support (20) inside the vessel. The pressure vessel can be made of SA543 Gr.B with a thickness of 300t for a 200 bar standard, and can be made of SUS with a thickness of about 50t for a 7 bar standard. In a double-structured vessel including inner and outer shells, a saddle is installed between the inner and outer shells to support thermal deformation of the SUS.

[0011] For pressure vessels to be economical, the storage capacity of LNG must be increased, and to achieve this, they must be able to operate under high pressure conditions of 200 bar or higher. However, LNG, which has a boiling point of around -163°C, is extremely cold and sensitive to temperature changes, causing it to vaporize easily. Therefore, pressure vessels must satisfy these thermal performance, deformation resistance, pressure resistance, and strength requirements. Consequently, there were problems such as high manufacturing costs due to increased thickness, and difficulties in scaling up due to weight and weldability.

[0012] The present invention aims to solve these problems by proposing an LNG storage pressure vessel that is easy to manufacture and can accommodate deformation caused by temperature and pressure, as well as ships and offshore structures equipped with such a pressure vessel. means of solving the problem

[0013] According to one aspect of the present invention, in a pressure vessel for storing LNG,

[0014] An inner shell comprising a plurality of layers including a graphene layer and storing LNG inside;

[0015] An outer shell provided to surround the outer side of the inner shell; and

[0016] Including an insulating layer provided between the inner shell and the outer shell,

[0017] An LNG storage pressure vessel is provided, characterized in that the graphene layer of the inner shell can absorb deformation caused by the pressure of the LNG.

[0018] Preferably, the inner shell comprises a SUS layer made of SUS and in contact with the LNG contained within the pressure vessel; and the

[0019] It includes a graphene layer arranged to surround the outer side of a SUS layer, and the SUS layer and the graphene layer can be bonded by glue bonding.

[0020] Preferably, the inner shell may include a graphene layer in contact with LNG contained inside the pressure vessel; a SUS layer arranged to surround the outer side of the graphene layer; and a vacuum insulation layer arranged between the graphene layer and the SUS layer.

[0021] Preferably, the outer shell may be made of mild steel.

[0022] According to another aspect of the present invention, a vessel having a pressure vessel for LNG storage as described above is provided.

[0023] According to another aspect of the present invention, an offshore structure having a pressure vessel for LNG storage as described above is provided. Effects of the invention

[0024] In the pressure vessel for LNG storage according to the present invention, by providing an inner shell including a graphene layer, deformation caused by the increase in internal pressure due to the cryogenic temperature of LNG and the generation of boil-off gas can be accommodated in the graphene layer, thereby enabling safe storage and transportation of LNG.

[0025] In addition, by applying flexible and high-strength graphene to pressure vessels, manufacturing is facilitated and the vessel thickness can be reduced. Furthermore, economic efficiency can be enhanced as LNG can be stored and transported economically without the need for separate reliquefaction or boil-off gas exhaust devices.

[0026] By equipping ships or offshore structures with such pressure vessels for LNG storage, it contributes to securing onboard space and enables safer and more effective transportation of LNG. Brief explanation of the drawing

[0027] FIG. 1 schematically illustrates an example of a conventional pressure vessel for storing LNG. FIG. 2 schematically illustrates a cross-sectional view of a pressure vessel for LNG storage according to a first embodiment of the present invention. FIG. 3 schematically illustrates a cross-sectional view of a pressure vessel for LNG storage according to a second embodiment of the present invention. Specific details for implementing the invention

[0028] In order to fully understand the present invention, the operational advantages of the present invention, and the objectives achieved by the implementation of the present invention, reference must be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described therein.

[0029] The present invention will be described in detail below by explaining preferred embodiments of the invention with reference to the attached drawings. Identical reference numerals in each drawing indicate identical components.

[0030] FIG. 2 schematically illustrates a cross-sectional view of a pressure vessel for LNG storage according to a first embodiment of the present invention, and FIG. 3 schematically illustrates a cross-sectional view of a pressure vessel for LNG storage according to a second embodiment of the present invention.

[0031] As illustrated in FIGS. 2 and 3, the pressure vessel for LNG storage of the embodiments is a pressure vessel for storing LNG, comprising an inner shell (100A, 100B) that stores LNG inside and includes a plurality of layers including a graphene layer, an outer shell (200A, 200B) that is arranged to surround the outer side of the inner shell, and an insulating layer (300A, 300B) that is arranged between the inner shell and the outer shell, so as to be able to absorb deformation caused by the pressure of the LNG in the graphene layer (110A, 110B) of the inner shell.

[0032] Graphene is a term created by combining 'graphite' and the suffix '-ene,' which denotes a molecule with carbon double bonds, and refers to a membrane-like material composed of carbon atoms.

[0033] Graphite consists of a structure in which carbon atoms are stacked in layers in a hexagonal honeycomb shape. Graphene is the thinnest single layer peeled off from graphite; as a carbon allotrope, graphene is a nanomaterial composed of carbon, which has atomic number 6, just like carbon nanotubes and fullerenes. In 2004, a research team at the University of Manchester in the UK created graphene with a perfect two-dimensional structure at room temperature by peeling it off from graphite using the adhesive force of Scotch tape.

[0034] Graphene is a two-dimensional planar material with a thickness of 0.2 nm (approximately 2 ten-billionths of a meter), making it thin and highly stable in terms of physical and chemical properties. It conducts electricity more than 100 times better than copper and can move electrons more than 100 times faster than single-crystal silicon, which is primarily used as a semiconductor. It is more than 200 times stronger than steel and has more than twice the thermal conductivity of diamond. Furthermore, due to its excellent elasticity, it retains its electrical properties even when stretched or bent.

[0035] Due to these characteristics, graphene is evaluated as a material that surpasses carbon nanotubes, which are currently in the spotlight as next-generation new materials, and is called the "dream nanomaterial." Although graphene and carbon nanotubes have very similar chemical properties, graphene has greater potential for industrial applications because it possesses more uniform metallic properties than carbon nanotubes.

[0036] Graphene is attracting attention as a future new material in the electronic information industry that can be used to make bendable displays, electronic paper, wearable computers, etc. In these embodiments, focusing on these characteristics of graphene, a graphene layer was provided on the inner shell of a pressure vessel capable of storing LNG.

[0037] First, as shown in FIG. 2, in the pressure vessel of the first embodiment, the inner shell (100A) is made of SUS and includes a SUS layer (120A) in contact with LNG contained inside the pressure vessel and a graphene layer (110A) arranged to surround the outer side of the SUS layer.

[0038] The SUS layer and the graphene layer are bonded together by glue bonding (130A).

[0039] In the pressure vessel of this first embodiment, even if the SUS layer (120A) expands and deforms due to the rise in internal pressure of the vessel caused by evaporated gas and the cryogenic temperature of the LNG, the glue-bonded graphene layer (110A) accommodates and prevents such deformation, thereby allowing the LNG to be stored safely.

[0040] As illustrated in FIG. 3, in the pressure vessel of the second embodiment, the inner shell (100B) comprises a graphene layer (110B) in contact with the LNG contained inside the pressure vessel, a SUS layer (120B) arranged to surround the outer side of the graphene layer, and a vacuum insulation layer (130B) arranged between the graphene layer and the SUS layer. In the pressure vessel of the second embodiment, the graphene layer (110B) itself serves as the innermost vessel for storing LNG. Since the graphene layer has high strength and can withstand expansion due to pressure rise when in contact with cryogenic LNG, once the expanded shape is formed to some extent, the SUS layer (120B) merely holds the position of the graphene layer. The vacuum insulation layer (130B) between the graphene layer and the SUS layer performs a primary insulation function, and the insulation layer portion (300B) between the inner shell and the outer shell performs a secondary insulation function.

[0041] Meanwhile, in the first and second embodiments, the outer shell (200A, 200B) is made of mild steel.

[0042] When the pressure vessels of these embodiments are applied to ships, etc., the deformation caused by the pressure rise due to the boil-off gas generated during LNG storage in the inner shell containing the graphene layer can be accommodated up to 200 bar, so a reliquefaction device for reliquefying and storing the boil-off gas may not be required, making it economical.

[0043] Table 1 below compares the graphene layer applied to the inner shell of the embodiments required to manufacture a pressure vessel capable of withstanding a pressure of 200 bar with the required thickness and price when using SA543 Gr.B material. Explanation of the symbols

[0044] 100A, 100B: Inner shell 110A, 110B: Graphene layer 120A, 120B: SUS layer 130A: Glue bonding layer 130B: Vacuum insulation layer 200A, 200B: External shell 300A, 300B: Insulation layer

Claims

Claim 1 A pressure vessel for storing LNG, comprising: an inner shell that stores LNG and includes a plurality of layers including a graphene layer; an outer shell provided to surround the outer side of the inner shell; and an insulating layer provided between the inner shell and the outer shell, wherein the graphene layer of the inner shell can absorb deformation caused by the pressure of the LNG. Claim 2 A pressure vessel for LNG storage according to claim 1, wherein the inner shell is made of SUS and includes a SUS layer in contact with LNG contained inside the pressure vessel; and a graphene layer provided to surround the outer side of the SUS layer, wherein the SUS layer and the graphene layer are bonded by glue bonding. Claim 3 In claim 1, the pressure vessel for LNG storage comprises: an inner shell in contact with LNG contained within the pressure vessel; a SUS layer provided to surround the outer side of the graphene layer; and a vacuum insulation layer provided between the graphene layer and the SUS layer.

Images