A sealed and insulated container for transporting liquefied natural gas

Abstract

The present invention relates to a sealed and insulated container for transporting liquefied natural gas. The sealed and insulated container contains liquefied natural gas and is disposed within the hull of a transport vessel as a containment system. The sealed and insulated container comprises two thin film shielding layers and two insulating layers, namely, from the inside out, a first thin film shielding layer, a first insulating layer, a second thin film shielding layer, and a second insulating layer. The first square insulating blocks in the first insulating layer and the second square insulating blocks in the second insulating layer are arranged in a staggered arrangement, such that the inter-plate gaps in the first insulating layer and the inter-plate gaps in the second insulating layer are staggered. Metal connectors at the four corners of each first square insulating block are connected to the center of the second square insulating block. The present invention avoids direct heat conduction between the inter-plate gaps by staggering the insulating layers. The circulating double-layer channels prevent cold leakage. The modular arrangement is convenient and quick to install, and highly safe.

Description

Technical Field

[0001] The present invention relates to the technical field of liquefied natural gas storage and transportation equipment, and in particular to a sealed and insulated container for liquefied natural gas transportation. Background Art

[0002] Liquefied natural gas is stored and transported at ultra-low temperatures, as low as -163°C. Therefore, the type of containment for cargo holds that are in direct contact with liquefied natural gas is extremely important.

[0003] Currently, the liquid cargo containment systems used on large LNG carriers include spherical tanks (MOSS), membranes, and SPBs. Developed by Rosenberg, a Norwegian company, the spherical tank has a spherical shape and no loading level restrictions. The tanks are constructed of A5083 aluminum alloy and covered with polyurethane insulation. These systems are expensive and heavy. Developed by GTT, a French company, the membrane tanks include the NO.96, Mark III, and CS1 types. All three types utilize a 0.7 mm thick metal membrane as the cargo hold lining, along with insulation and a secondary isolation layer. These layers are secured to the hull, but the membrane's ability to withstand liquid cargo sloshing loads is limited, and the complex structure of the cargo hold requires a long construction period. The SPB cargo hold, developed by Ishikawajima-Harima Heavy Industries (IHI) of Japan, features a ribbed plate structure constructed of 9-nickel steel. This structure is complex and expensive. In addition, South Korea has also developed the KC-1 film liquid cargo containment system. The main layer and the secondary layer are both made of 1.5 mm thick metal material, but the two layers of film are the same and have a complex structure, making prefabrication difficult. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of existing technologies by designing a sealed and insulated container for liquefied natural gas transportation. The sealed and insulated container of the present invention is used for liquefied natural gas transportation. A circulating channel is constructed through a first insulating space and a second insulating space, and a specific configuration is employed to effectively reduce cold leakage, forming a novel dual-channel membrane ultra-low-temperature LNG storage vehicle.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A sealed and insulated container for transporting liquefied natural gas, which is arranged inside the hull of a transport ship as a containment system. The sealed and insulated container comprises, from the inside to the outside, a first film shielding layer, a first insulating layer, a second film shielding layer, and a second insulating layer. The first film shielding layer is a continuous, sealed stainless steel corrugated plate welded together, which is in direct contact with the liquefied natural gas. The first insulating layer is a layered structure formed by splicing a plurality of first square insulating panels, with a first inter-panel gap between adjacent first square insulating panels. The stainless steel corrugated plate is fixed to the first square insulating panel. The second film shielding layer includes a layered composite material and a flexible sealing material. The layered composite material is a sandwich-shaped structure formed by two layers of glass cloth sandwiched with a layer of hard aluminum foil. The flexible sealing material is a composite of glass fiber and soft aluminum foil, the second insulating layer is a layered structure formed by splicing second square insulating panels, the layered composite material is fixed on the second square insulating panels, and a second inter-panel gap is left between adjacent second square insulating panels. The flexible sealing material covers the second inter-panel gap and is placed on the adjacent layered composite material. The second insulating layer is fixed to the hull structure by epoxy resin; the first square insulating panels in the first insulating layer and the second square insulating panels in the second insulating layer are arranged in a staggered arrangement, so that the first inter-panel gap in the first insulating layer and the second inter-panel gap in the second insulating layer are staggered with each other, and the metal connectors at the four corners of each first square insulating block pass through the center of the second square insulating block and are fixed to the hull structure.

[0007] In a sealed and insulated container for liquefied natural gas transportation of the present invention, the first film shielding layer is made of 304L stainless steel, and a plurality of crisscrossing raised stripes are pressed on the stainless steel. The crossed raised stripes form a corrugated shape to form a stainless steel corrugated plate.

[0008] In a sealed and insulated container for transporting liquefied natural gas according to the present invention, further, each first square insulating panel comprises a polyurethane foam panel and a plywood panel, the plywood panel being bonded and fixed to the upper and lower surfaces of the polyurethane foam panel, the stainless steel corrugated panel being connected and fixed to the plywood panel on the upper surface of the first square insulating panel via anchors, adjacent stainless steel corrugated panels being seamlessly welded to form a sealing layer, and the sealed stainless steel corrugated panels forming a cavity for accommodating the liquefied natural gas.

[0009] In a sealed and insulated container for transporting liquefied natural gas according to the present invention, each second square insulating block comprises a polyurethane foam board and a plywood bonded together, the plywood being bonded and fixed to the upper and lower surfaces of the polyurethane foam board, the layered composite material being arranged in a block shape, each layered composite material being adhered and fixed to the plywood on the upper surface of the second square insulating block, and each layered composite material being equal in size to the plywood, the layered composite material and the flexible sealing material forming a continuous second thin film shielding layer.

[0010] In the sealed and insulated container for liquefied natural gas transportation of the present invention, further, the inter-plate spaces between adjacent square insulating blocks in the first insulating layer are filled with glass wool, and the bottom openings of the inter-plate spaces are also adhered with the layered composite material.

[0011] In a sealed and insulated container for transporting liquefied natural gas (LNG) according to the present invention, a sensing system for detecting natural gas leaks is disposed within the second insulating layer. The sensing system comprises a temperature measurement host and a fiber optic network. The fiber optic network comprises multiple optical fibers arranged vertically and horizontally within the interstices between the second plates. These optical fibers form a distributed detection network and feed back detection optical signals to the temperature measurement host. Multiple distributed temperature measurement hosts are provided, one for each large surface.

[0012] In a sealed and insulated container for transporting liquefied natural gas according to the present invention, the first and second insulating layers are prefabricated into modular groups, each of which includes at least four first square insulating panels and nine second square insulating panels. The four first square insulating panels are spliced ​​together to form a large 2×2 square panel array, and the nine second square insulating panels are spliced ​​together to form a large 3×3 square panel array. The 2×2 square panel array is fixed to the top center of the 3×3 square panel array.

[0013] In a sealed and insulated container for liquefied natural gas transportation according to the present invention, further, a large-area insulation layer is formed on the inner wall of the hull on the module group, and first square insulation panels are filled between adjacent 2×2 square panel arrays. The filled first square insulation panels cover the flexible sealing material in the second film shielding layer. The filled first square insulation panels and the adjacent 2×2 square panel arrays form a full paving, and the first square insulation panels in the full paving serve as the first insulation layer.

[0014] Based on the above technical solution, the sealed and insulated container of the present invention is used in the storage and transportation of liquefied natural gas, and has achieved the following positive beneficial effects:

[0015] 1. The present invention features a simple structure and low cost, effectively solving the problems of LNG storage and leakage prevention. The second membrane barrier effectively prevents leakage from the first membrane barrier. The second membrane barrier also serves to receive cryogenic liquid, preventing brittle cracking of the hull steel plate caused by contact with the cryogenic liquid and ensuring the safety of the vessel.

[0016] 2. The sealed and insulated container of the present invention is used for the storage and transportation of liquefied natural gas. By staggering the first insulating layer space and the second insulating layer space, heat conduction in an upper and lower aligned arrangement is avoided, forming a double barrier wall for the circulating channel, greatly reducing cold leakage and effectively ensuring the integrity of the enclosure system.

[0017] 3. The sealed and insulated container of the present invention adopts a two-layer insulation setting to ensure that in the event of leakage in the first film screen, the second insulation layer blocks most of the cold energy conduction, ensuring that the hull steel plate is within the allowable operating temperature range, further improving the safety of the containment system.

[0018] 4. The sealed and insulated container of the present invention allows the insulating layers to move within a certain range by filling glass wool between adjacent insulating layers to absorb the energy of thermal expansion and contraction of the enclosure system, thereby greatly improving the overall safety performance of the enclosure system.

[0019] 5. In order to detect the leakage of cryogenic liquid in the shortest possible time, the sealed and insulated container of the present invention has a DTS (distributed fiber optic detection system) arranged between the first and second insulation layers. The DTS detects temperature changes in real time through the arrangement of optical fibers. If temperature anomalies occur, an alarm is issued in a timely manner to determine the location and scope of the leakage, thereby facilitating subsequent repair measures.

[0020] 6. The sealed and insulated container of the present invention prefabricates the first insulating layer and the second insulating layer into a grouped module group, and finally fixes the 2×2 square plate array at the top middle position of the 3×3 square plate array. The purpose of forming the module group is to ensure that the first square insulating plate in the first insulating layer can cover the inter-plate gaps between the square insulating plates in the second insulating layer, and the combined assembly can better reflect the integrity and aesthetics, fully realize the staggered arrangement, and reduce the risk of heat conduction and cold leakage.

[0021] 7. The sealed and insulated container of the present invention is laid on the inner wall of the hull on the module group to form a large-area insulation layer, and a first square insulation plate is filled between adjacent 2×2 square plates. The filled first square insulation plate covers the flexible sealing material in the first thin film shielding layer, and the filled first square insulation plate and the adjacent 2×2 square plates form a full paving, and a first thin film shielding layer that is continuously welded into one is provided on the fully paved first square insulation plate. Through modular construction, the quality and size requirements of the staggered distribution can be guaranteed, and the construction difficulty can be reduced and the construction efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a schematic diagram of the three-dimensional structure of a module group in a sealed and insulated container for transporting liquefied natural gas.

[0023] Figure 2 The figure is a cross-sectional schematic diagram of a module group in a sealed and insulated container for transporting liquefied natural gas according to the present invention.

[0024] Figure 3 yes Figure 2 A is an enlarged schematic diagram.

[0025] Figure 4 The figure is a schematic diagram of the overall structure of a sealed and insulated container for transporting liquefied natural gas according to the present invention.

[0026] The specific meanings of the numbers in the figure are: 1 is the first film screen layer, 2 is the plywood, 3 is the polyurethane foam board, 4 is the second film screen layer, 5 is the glass wool between the polyurethane foam boards, 6 is the layered composite material, 7 is the flexible sealing material, 8 is the metal connector, and 9 is the optical fiber. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0028] This embodiment is a sealed and insulated container for transporting liquefied natural gas (LNG). The LNG is placed in this sealed and insulated container, which serves as a containment system installed within the hull of a transport vessel. In practice, this system is typically used to load LNG onto large LNG carriers, enabling long-distance, high-capacity transport. As a sealed and insulated container, the containment system must maintain low-temperature insulation for the LNG it contains, preventing cold leaks during transport, minimizing heat exchange, and improving safety.

[0029] like Figure 1 、 Figure 2 and Figure 3 As shown, the sealed and insulated container as a containment system includes two thin film shielding layers and two insulating layers, which are respectively a first thin film shielding layer 1, a first insulating layer, a second thin film shielding layer 4 and a second insulating layer from the inside to the outside. The first thin film shielding layer 1 is a continuous, sealed stainless steel corrugated plate welded together, which is in direct contact with the liquefied natural gas.

[0030] The first thin film shielding layer 1 is typically made of 304L stainless steel. Multiple crisscrossing raised stripes are pressed into the flat stainless steel surface. These intersecting raised stripes form a corrugated pattern, creating a stainless steel corrugated plate. Since LNG is an ultra-cold liquid at -163°C, the film shielding material in direct contact with the LNG liquid must meet low-temperature plasticity requirements and be able to overcome expansion and contraction when cooled from room temperature to low temperatures. The choice of insulation material must also take into account factors such as the cargo hold structure and the required evaporation rate. In this embodiment, the first thin film shielding layer 1 is made of 304L stainless steel and pre-formed into a corrugated shape, enhancing its ability to overcome expansion and contraction.

[0031] The above-mentioned stainless steel corrugated plates are tightly attached to the plywood of the first insulating layer and are connected and fixed by anchors. The adjacent stainless steel corrugated plates are seamlessly welded to form a sealing layer, which becomes the first thin film shielding layer. Usually, the first thin film shielding layer is made into a large octagonal columnar chamber, and the sealed stainless steel corrugated plates form a cavity to accommodate liquefied natural gas.

[0032] The first insulating layer is a layered structure formed by splicing a plurality of first square insulating panels. Each first square insulating panel includes a polyurethane foam panel 3 and a plywood 2 bonded together. The upper and lower surfaces of the polyurethane foam panel 3 are bonded and fixed with the plywood 2. Anchors are provided on the plywood 2 of each first square insulating panel. The stainless steel corrugated plate is welded to the anchors of the plywood 2 on the upper surface of the polyurethane foam panel 3. A first inter-panel gap is left between adjacent first square insulating panels. The first inter-panel gap is filled with glass wool, that is, the adjacent polyurethane foam panels 3 are filled with polyurethane foam inter-panel glass wool 5.

[0033] The second thin film shielding layer 4 is bonded and fixed to the second insulating layer. The second thin film shielding layer 4 is composed of a layered composite material 6 and a flexible sealing material 7. The layered composite material 6 is a sandwich structure formed by two layers of glass cloth sandwiched with a layer of hard aluminum foil. The flexible sealing material 7 is a composite of glass fiber and soft aluminum foil. Although both contain aluminum foil to achieve sealing, the material requirements vary depending on the location. The hard aluminum foil is used to enhance support performance, while the soft aluminum foil is used to enhance elastic deformation performance. The second insulating layer is a layered structure composed of multiple second square insulating panels. Each second square insulating panel includes a polyurethane foam board 3 and a plywood 2 bonded together. The plywood 2 is bonded and fixed to the upper and lower surfaces of the polyurethane foam board 3. The layered composite material 6 is fixed to the plywood 2 on the upper surface of each second square insulating panel. The second inter-panel gaps between adjacent second square insulating panels are filled with glass wool, namely, glass wool 5 between the polyurethane foam panels. The flexible sealing material 7 covers the second inter-panel gaps and rests on the adjacent layered composite material 6. The second thin-film shielding layer 4 is composed of multiple blocks of laminated composite material 6 connected by flexible sealing material 7 between the laminated composite materials 6. If a leak occurs in the first thin-film shielding layer 1, the second thin-film shielding layer 4 prevents further leakage of cryogenic liquid or gas into the hull until the vessel is repaired or brought to a port for specialized repairs. This second thin-film shielding layer 4, unlike the first thin-film shielding layer 1, offers improved safety and ease of construction.

[0034] Furthermore, because glass wool is filled between adjacent second square insulation panels in the second insulation layer, the elasticity of the glass wool allows the second insulation layer to move within a certain range when the enclosure system expands or contracts, ensuring the safety and reliability of the enclosure system. The second insulation layer is fixed to the hull structure using epoxy resin. Specifically, the second insulation layer is close to the inner wall of the hull, and epoxy resin is poured into the gaps to achieve bonding and fixation.

[0035] A key feature of this invention is the staggered arrangement of the first square insulating blocks in the first insulating layer and the second square insulating blocks in the second insulating layer, resulting in the first inter-plate gaps in the first insulating layer and the second inter-plate gaps in the second insulating layer being offset from each other. Furthermore, metal connectors 8 at the four corners of each first square insulating block on the first insulating layer are connected to the center of the second square insulating block in the second insulating layer. The bottom of these metal connectors 8 is fixed to the hull, passing through the center of each second square insulating block and extending to secure the four corners of the first square insulating block in the first insulating layer. Because the upper portion of the glass wool filling the second inter-plate gaps in the second insulating layer is sealed with a flexible composite material 7, in the event of a leak in the first thin film shielding layer 1, the second thin film shielding layer 2 can be used for temporary sealing, ensuring the integrity and tightness of the system. The first insulating layer is fixed to the second insulating layer via the metal connectors 8, effectively and evenly transferring the impact force of liquid cargo sloshing to the hull structure below the second insulating layer, avoiding stress concentration and ensuring system safety.

[0036] In order to ensure the precise implementation of staggered distribution, the sealed and insulated container of the present invention prefabricates the first insulating layer and the second insulating layer into grouped module groups, and finally fixes the 2×2 square plate array at the top middle position of the 3×3 square plate array. The purpose of forming the module group is to ensure that the first square insulating plate in the first insulating layer can cover the inter-plate gaps between the square insulating plates in the second insulating layer, and the combined assembly can better reflect the integrity and aesthetics, fully realize the staggered arrangement, and reduce the risk of heat conduction and cold leakage.

[0037] In addition, multiple factory-prefabricated modular panels are transported aboard and laid on the hull's inner wall to form a large-area insulation layer. After the modular panels are laid, first square insulation panels are added to the gaps between adjacent 2×2 square panels as a supplement. These first square insulation panels cover the flexible sealing material in the first thin-film shielding layer. Furthermore, these first square insulation panels and the adjacent 2×2 square panels form a fully covered first insulation layer. After the first insulation layer is completed, continuously welded corrugated stainless steel is laid on top of the fully covered first square insulation panels to form the first thin-film shielding layer. Modular construction ensures both the quality and dimensional requirements of the staggered distribution are met while reducing construction difficulty and improving efficiency.

[0038] In order to detect liquid leakage, a sensor for detecting natural gas leakage is arranged in the gap between the second plates. The sensor is an optical fiber network with multiple optical fibers 9 arranged vertically and horizontally on the optical fiber network. The optical fibers 9 form a distributed detection network and feed back the detection light signal to the distributed temperature measurement host. Specifically, the optical fiber 9 is zigzag through the gap between the second plates and close to the flexible sealing material 7, such as Figure 3 Placing the optical fiber 9 of the optical fiber sensing system in the gap between the second plates can ensure sufficient safety and construction convenience. At the same time, since the temperature of the leaked liquefied natural gas changes significantly, it can also accurately detect the temperature change, thereby achieving leakage warning.

[0039] Furthermore, the distributed temperature measurement host is provided in multiple units, with one distributed temperature measurement host corresponding to each large surface. Figure 4 As shown in the figure, the completed containment system takes on the shape of an octagonal prism. The optical fibers of the fiber optic sensors are placed through the gaps between the second panels. The plane between the two prisms forms a large surface, with a total of eight large surfaces. Placing a distributed temperature measurement host on each large surface allows for more accurate temperature detection, thereby determining whether a cooling leak has occurred and locating the exact location of the leak. The distributed fiber optic sensing system uses optical fibers in the gaps between the second panels to detect temperature changes in real time. If a temperature anomaly occurs, an alarm is triggered, confirming the location and scope of the leak and assisting in subsequent repairs.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions for which protection is sought in the present invention.

Claims

1. A sealed and insulated container for transporting liquefied natural gas, the sealed and insulated container being installed inside the hull of a transport vessel as a containment system. The sealed and insulated container comprises, from the inside to the outside, a first film shielding layer, a first insulating layer, a second film shielding layer, and a second insulating layer. The first film shielding layer is a continuous, sealed stainless steel corrugated plate welded together, which is in direct contact with the liquefied natural gas. The container is characterized in that: The first insulating layer is a layered structure formed by splicing together a plurality of first square insulating panels, with first inter-panel gaps being left between adjacent first square insulating panels. The corrugated stainless steel sheet is fixed to the first square insulating panels. The second thin film shielding layer comprises a layered composite material and a flexible sealing material. The layered composite material is a sandwich structure formed by two layers of glass cloth sandwiching a layer of hard aluminum foil. The flexible sealing material is a composite of glass fiber and soft aluminum foil. The second insulating layer is a layered structure formed by splicing together second square insulating panels. The layered composite material is fixed to the second square insulating panels, with second inter-panel gaps being left between adjacent second square insulating panels. The flexible sealing material covers the second inter-panel gaps and rests on adjacent layered composite materials. The second insulating layer is fixed to the hull structure using epoxy resin. The first square insulating panels in the first insulating layer and the second square insulating panels in the second insulating layer are arranged in a staggered arrangement, such that the first inter-panel gaps in the first insulating layer and the second inter-panel gaps in the second insulating layer are staggered with each other, and the metal connectors at the four corners of each first square insulating panel pass through the center of the second square insulating panel and are fixed to the hull structure; the first insulating layer and the second insulating layer are prefabricated into modular groups, each modular group including four first square insulating panels and nine second square insulating panels, the four first square insulating panels being spliced ​​together to form a large 2×2 square panel array, and the nine second square insulating panels being spliced ​​together to form a large 3×3 square panel array, the 2×2 square panel array being fixed at the top center of the 3×3 square panel array; The module group is laid on the inner wall of the hull to form a large-area insulation layer. A first square insulation plate is filled between adjacent 2×2 square plate arrays. The filled first square insulation plate covers the flexible sealing material in the second thin film shielding layer. The filled first square insulation plate and the adjacent 2×2 square plate array form a full paving, and the fully paved first square insulation plate serves as the first insulation layer.

2. A sealed and insulated container for liquefied natural gas transportation according to claim 1, characterized in that: The first film shielding layer is made of 304L stainless steel, and a plurality of crisscross raised stripes are pressed on the stainless steel. The crossed raised stripes form a corrugated shape to form a stainless steel corrugated plate.

3. A sealed and insulated container for liquefied natural gas transportation according to claim 2, characterized in that: Each first square insulating panel includes a polyurethane foam panel and a plywood panel. The plywood panel is bonded and fixed to the upper and lower surfaces of the polyurethane foam panel. The stainless steel corrugated panel is connected and fixed to the plywood panel on the upper surface of the first square insulating panel via anchors. Adjacent stainless steel corrugated panels are seamlessly welded to form a sealing layer. The sealed stainless steel corrugated panels form a cavity for accommodating liquefied natural gas.

4. A sealed and insulated container for liquefied natural gas transportation according to claim 1, characterized in that: Each second square insulating panel includes a polyurethane foam board and a plywood bonded together, the plywood being bonded and fixed to the upper and lower surfaces of the polyurethane foam board. The layered composite material is arranged in a block shape, and each layered composite material is adhered and fixed to the plywood on the upper surface of the second square insulating panel. The size of each layered composite material is equal to that of the plywood. The layered composite material and the flexible sealing material form a continuous second thin film shielding layer.

5. A sealed and insulated container for liquefied natural gas transportation according to claim 1, characterized in that: The first inter-plate gaps between adjacent first square insulation plates in the first insulation layer are filled with glass wool, and the second inter-plate gaps between adjacent second square insulation plates in the second insulation layer are also filled with glass wool.

6. A sealed and insulated container for liquefied natural gas transportation according to claim 1, characterized in that: A sensing system for detecting natural gas leakage is arranged in the second insulating layer. The sensing system includes a temperature measuring host and an optical fiber network. The optical fiber network includes multiple optical fibers arranged vertically and horizontally in the gaps between the second plates. The optical fibers form a distributed detection network and feed back the detection light signal to the temperature measuring host.

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