A ship for the storage and transport of cryogenic liquid cargo

Abstract

The application relates to the technical field of liquefied gas transport ships, in particular to a low-temperature liquid cargo storage and transport ship which comprises a liquid cargo cabin body, the inner wall of the liquid cargo cabin body is fixedly provided with a film enclosure system, the film enclosure system comprises an adiabatic layer, the adiabatic layer is bonded on the liquid cargo cabin body by a plurality of adiabatic boxes through epoxy mortar, the adiabatic box comprises upper and lower plywood and polyurethane foam blocks, the side wall of the storage tank has first and second wall surface areas, the epoxy mortar coating mode, interval, adiabatic box arrangement and polyurethane foam block density of different areas are different, and the epoxy mortar of the corner area of adjacent wall surface areas is in the form of a round cake. The application provides an adiabatic box structure and bonding method of the low-temperature liquid cargo storage and transport ship, can realize differentiated matching of the adiabatic box and the mortar bonding system and the distribution form of the liquid cargo sloshing impact load, and improves the impact resistance and long-term service reliability of the high-load area.

Description

Technical Field

[0001] This application relates to the field of liquefied gas transport ship technology, and in particular to a vessel for storing and transporting cryogenic liquid cargo. Background Technology

[0002] Liquefied natural gas (LNG) carriers play a vital role in global energy trade, and the cryogenic liquid cargo they transport is crucial for energy supply and economic development. With the continuous development of the shipping industry, higher demands are being placed on the performance and safety of LNG carriers. Membrane containment systems, as an important structure for storing and insulating cryogenic liquid cargo, directly affect the safety and operational efficiency of the vessel. A well-designed containment system can effectively reduce the loss of cryogenic liquid cargo and improve the vessel's transport capacity and economic benefits.

[0003] In existing technologies, liquefied natural gas (LNG) carriers typically employ membrane-type containment systems to address the storage and insulation challenges of cryogenic liquid cargoes. The insulation layer of this system generally consists of multiple insulated boxes bonded to the hull bulkhead using epoxy resin mortar. Each insulated box typically comprises an upper plywood layer, a lower plywood layer, and a polyurethane foam block sandwiched between them. Epoxy resin mortar is applied in discontinuous strips between the lower plywood and the bulkhead, thus securing the insulated box to the hull and providing load-bearing and load-transfer functions. Furthermore, the traditional approach to designing the arrangement of the insulated boxes and epoxy resin mortar involves using uniform insulated box specifications and a uniform mortar application method, i.e., applying mortar strips of the same density to all walls of the tank. There is a lack of systematic design to coordinate the application direction of the mortar strips with the side length direction of the insulated box to address load variations.

[0004] However, this existing technology has significant drawbacks. During ship navigation, wind and waves cause the hull to roll, pitch, and sway, resulting in violent shaking of the cryogenic liquid cargo inside the tank. The resulting impact loads act on the walls of the containment system, exhibiting a significantly non-uniform distribution across the tank walls. The current one-size-fits-all design paradigm leads to a mismatch between the system's structural resistance and the actual load distribution. The safety margin is insufficient in wall areas subjected to larger impact loads, making the lower plywood prone to bending failure, which in turn causes polyurethane foam cracking and a decrease in insulation performance. Simultaneously, uneven stress distribution at the adhesive bonding interface leads to localized stress concentration, causing adhesive cracking and detachment, affecting the long-term reliability of the bonded structure. Conversely, in wall areas subjected to smaller impact loads, there is a waste of material properties. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this application provides an insulation box structure and bonding method for a cryogenic liquid cargo storage and transportation vessel, which can achieve differentiated matching between the insulation box and the putty bonding system and the distribution pattern of liquid cargo sloshing impact load, thereby improving the impact resistance and long-term service reliability of high-load areas.

[0006] This application is achieved through the following technical solution:

[0007] A vessel for storing and transporting cryogenic liquid cargo includes a liquid cargo hull. A membrane enclosure system is fixed to the inner wall of the liquid cargo hull. The membrane enclosure system includes an insulation layer, which is formed by multiple insulation boxes bonded to the liquid cargo hull with epoxy resin putty. Each insulation box includes an upper plywood, a lower plywood, and a polyurethane foam block sandwiched between the upper and lower plywood. Epoxy resin putty is applied between the lower plywood and the liquid cargo hull. The membrane enclosure system forms a storage tank for containing liquefied gas. The storage tank has two side walls arranged opposite each other along the width of the hull. The side walls have a first wall area arranged vertically and a second wall area arranged inclined. The epoxy resin mortar in the first and second wall areas is applied in a discontinuous strip structure, and the spacing between adjacent epoxy resin mortar pieces in the first wall area is smaller than the spacing between adjacent epoxy resin mortar pieces in the second wall area; the epoxy resin mortar coating direction on the side wall is parallel to the length direction of the hull; the long side of the insulation box in the first wall area is parallel to the epoxy resin mortar coating direction, and the short side of the insulation box in the second wall area is parallel to the epoxy resin mortar coating direction; the density of the polyurethane foam blocks used in the insulation box in the first wall area is greater than the density of the polyurethane foam blocks used in the insulation box in the second wall area.

[0008] By adopting the above technical solution, based on the different stress characteristics of the first wall area in the vertical direction bearing a large horizontal swaying impact load and the second wall area in the inclined direction bearing complex normal and tangential components and uneven thermal stress distribution, different epoxy resin putty coating spacings are set for each. The first wall area, with its smaller spacing, achieves higher bonding strength and load-bearing capacity, effectively preventing the insulation box from detaching or the lower plywood from bending and breaking under swaying loads. Simultaneously, the second wall area, with its larger spacing, retains necessary thermal displacement adjustment capacity, avoiding excessive thermally induced internal stress and cracking within the putty or foam block. The direction of the mortar coating is uniformly set parallel to the ship's length. Combined with the orientation design where the long side of the insulation box in the first wall area is parallel to it, and the short side of the insulation box in the second wall area is parallel to it, the extension direction of the mortar strips always matches the direction of optimal bending stiffness of the plywood under the insulation box and the load transfer path, significantly improving the stress uniformity of the bonding interface between the mortar and the lower plywood. Furthermore, higher-density polyurethane foam blocks are used in the first wall area to enhance the compressive and impact resistance of this area, while lower-density foam blocks are used in the second wall area, reducing material costs and improving insulation performance while meeting load-bearing requirements. The synergistic effect of these multiple technical features achieves a precise match between the structural resistance of the enclosure system and the actual load distribution, eliminating the problem of insufficient safety margin in high-load areas and avoiding material waste in low-load areas.

[0009] Optionally, a corner area is formed between each wall of the tank, and the epoxy resin putty in the corner area is in the shape of a disc.

[0010] By adopting the above technical solution, the epoxy resin putty is set in a disc shape instead of a strip shape at the corner area formed by the intersection of the walls. Since the corner area is often a geometric change and stress concentration location, the disc-shaped putty has isotropic stress characteristics and can evenly bear the load components from different directions. This avoids the edge peeling or shear failure that may occur in the corner area of ​​the strip putty, significantly improves the reliability of the corner bonding structure, and prevents the cascading failure of the enclosure system caused by the corner area being the first to fail.

[0011] Optionally, the thickness of the plywood under the insulation box located in the first wall area is greater than the thickness of the plywood under the insulation box located in the second wall area or corner area.

[0012] Optionally, the spacing between adjacent epoxy resin putty in the first wall area is 80mm~105mm; the diameter of epoxy resin putty in the corner area is greater than or equal to 50mm.

[0013] By adopting the above technical solution, the spacing between adjacent epoxy resin putty in the first wall area is limited to 80mm to 105mm, and the spacing between adjacent putty in the second wall area is larger than that in the first area. Simultaneously, the diameter of the disc-shaped putty in the corner area is set to be no less than 50mm. These specific numerical ranges were optimized through finite element analysis and fatigue testing based on the sway load spectrum of a typical liquefied gas carrier and the dimensions of the insulation box. The smaller spacing in the first area provides sufficient safety margin against debonding, while the larger spacing in the second area releases thermal stress while ensuring reliable adhesion. The diameter of the disc-shaped putty in the corner area, no less than 50mm, ensures that each putty point has sufficient bonding area and load dispersion capability, avoiding local pressure exceeding limits due to excessively small putty size. This achieves an optimal balance between material usage and structural reliability.

[0014] Optionally, each sidewall is composed of a central facade, an upper sloping surface, and a lower sloping surface. The upper sloping surface connects the top of the central facade to the top surface of the tank, and the lower sloping surface connects the bottom of the central facade to the bottom surface of the tank. The central facades of the two sides are the left and right facades, respectively. The left and right facades constitute the first wall area, and the upper and lower sloping surfaces constitute the second wall area. The epoxy resin putty applied to the top and bottom surfaces of the tank is parallel to the ship's length direction. The tank has a front and a back side arranged opposite each other along the ship's length direction. The epoxy resin putty applied to the front and back sides is perpendicular to the ship's length direction and parallel to the ship's height direction.

[0015] By adopting the above technical solution, the sidewall of the storage tank is further defined as consisting of a central vertical surface, an upper inclined surface, and a lower inclined surface. The left and right vertical surfaces are designated as the first wall surface area, and the upper and lower inclined surfaces as the second wall surface area. Simultaneously, the epoxy resin putty coating direction on the top and bottom surfaces of the storage tank is kept parallel to the ship's length direction. On the front and back surfaces, which are positioned opposite each other along the ship's length direction, the putty coating direction is perpendicular to the ship's length direction and parallel to the ship's height direction. This differentiated coating direction design considers the dominant load directions of each wall surface under the ship's roll and pitch motions: on the sidewall and top / bottom surfaces, the main load direction is transverse or vertical; applying the putty along the ship's length direction ensures that the long side of the strip-shaped putty is perpendicular to the shear direction caused by the load, thus obtaining the maximum shear resistance area. On the front and back surfaces, the main load direction is the ship's length direction; applying the putty perpendicular to the ship's length direction and parallel to the ship's height direction also ensures that the putty strips are perpendicular to the shear direction. Therefore, the shear resistance performance of the putty is maximized on all wall surfaces.

[0016] Optionally, the density of the polyurethane foam block in the first wall area is 150 kg / m³ to 200 kg / m³, and the density of the polyurethane foam block in the second wall area is 100 kg / m³ to 150 kg / m³.

[0017] By adopting the above technical solution, the polyurethane foam density of the first wall area is precisely controlled between 150 kg / m³ and 200 kg / m³, and that of the second wall area is controlled between 100 kg / m³ and 150 kg / m³. This optimized range is derived from a quantitative analysis of the load magnitude and insulation requirements of different areas. The vertical first wall area is subjected to significant liquid sloshing impact. Higher density foam has higher compressive strength and elastic modulus, which can effectively resist impact and reduce the bending deflection of the lower plywood. At the same time, its thermal conductivity is slightly higher, but the insulation performance requirements of this area are relatively low. The inclined second wall area has a smaller load and is more dependent on insulation performance. Lower density foam has a lower thermal conductivity, which can reduce heat leakage, and is sufficient to withstand the smaller load in this area, thus achieving an optimal match between structural strength and insulation efficiency.

[0018] Optionally, the epoxy resin putty used in the first wall area is a first-formula putty, and the epoxy resin putty used in the second wall area is a second-formula putty. The elastic modulus of the first-formula putty after curing is higher than that of the second-formula putty after curing, and the elongation at break of the first-formula putty after curing is lower than that of the second-formula putty after curing.

[0019] By adopting the above technical solution, a first-formulation mortar with a high elastic modulus and low elongation at break after curing is used in the first wall area, while a second-formulation mortar with a low elastic modulus and high elongation at break is used in the second wall area. This zonal configuration of material formulations perfectly matches the mechanical environment requirements of different areas. The high-intensity swaying loads borne by the first wall area require the mortar to have high stiffness and high shear resistance to strictly limit the displacement of the insulation box under impact. The high elastic modulus mortar can efficiently transfer the load to the hull structure without excessive deformation. In contrast, the second wall area, due to its inclination and proximity to the upper and lower corners of the tank, experiences large and frequent changes in thermal stress. Using a mortar with a low elastic modulus and high elongation at break can absorb the displacement caused by thermal deformation like a flexible buffer layer, preventing the mortar layer from cracking or detaching from the bulkhead due to rigid bonding. The synergistic use of the two mortar formulations allows different areas of the same enclosure system to operate in both rigid load-bearing and flexible adaptation modes, greatly improving the fatigue life of the system under complex multi-physics coupling effects.

[0020] Optionally, the insulation box in the first wall area has a fiber reinforcement layer embedded inside.

[0021] By adopting the above technical solution, the thickness of the plywood under the insulation box in the first wall area is greater than that in the second wall area, and a fiber reinforcement layer is embedded inside the insulation box in this area. This is a dual reinforcement measure for the structural strength of the insulation box in high-load areas. Increasing the thickness of the lower plywood directly improves its flexural section modulus, enabling it to more effectively resist bending stress caused by liquid sloshing impact; while the embedded fiber reinforcement layer, such as glass fiber or carbon fiber mesh, can significantly improve the in-plane shear strength and interlaminar peel strength of the plywood, preventing plywood delamination failure under high stress cycling. The second wall area has a smaller load and therefore does not require these reinforcement measures, thus ensuring the safety of critical areas while controlling the overall manufacturing cost.

[0022] Optionally, the total bonding area between the epoxy resin putty and the plywood under the insulation box is not less than 25% of the bonding surface of the plywood under the insulation box.

[0023] By adopting the above technical solution, the total bonding area between the epoxy resin mortar and the plywood under the insulation box is limited to no less than 25% of the total bonding area of ​​the plywood under the insulation box. This proportion is the minimum effective bonding area threshold obtained based on the mechanical analysis of the bonding interface and a large number of bonding strength tests. When the bonding area ratio is less than 25%, the shear stress borne by a single strip of mortar will exceed the shear strength of the mortar itself or the peel strength of the wood fibers on the surface of the plywood, and fatigue failure of the bonding interface is likely to occur under long-term alternating loads. However, when the ratio reaches or exceeds 25%, the bonding stress distribution generated by the mortar strip can make the stress in each area of ​​the plywood tend to be uniform, avoiding local stress peaks, thereby ensuring that the first wall area can still maintain a reliable bonding state after experiencing all shaking conditions within the design life.

[0024] Optionally, the bulkhead of the liquid cargo tank is provided with wedges or positioning holes for positioning the insulation boxes; the epoxy resin putty is arranged to avoid the wedges or positioning holes; and the gap between the two insulation boxes is filled with epoxy resin putty sealant.

[0025] By adopting the above technical solution, the insulation boxes are installed and positioned using pre-set wedges or positioning holes on the bulkhead of the liquid cargo tank. During the application of epoxy resin putty, these positioning structures are actively avoided, preventing the putty from contaminating the positioning surface or filling the positioning holes, which could lead to the insulation boxes not being accurately positioned. This ensures the installation accuracy and consistency of repeated positioning of the insulation boxes. At the same time, epoxy resin putty is also filled into the gap between two adjacent insulation boxes to seal the gap. This measure not only seals the gap to prevent the risk of cold brittleness caused by the leakage of cryogenic liquefied gas into the hull structure, but also allows adjacent insulation boxes to form a limited connection through the putty, enhancing the overall cohesive stress capacity of the insulation layer in the plane. This prevents a single insulation box from independently shifting or rotating due to swaying, further improving the structural integrity and sealing reliability of the enclosure system.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. This application sets different epoxy resin putty coating spacing, orientation and foam density according to the stress characteristics of different wall areas, so as to achieve precise matching between the structural resistance of the enclosure system and the actual load distribution, which not only eliminates the problem of insufficient safety margin in high load areas, but also avoids the waste of material properties in low load areas.

[0028] 2. This application maximizes the shear resistance of the putty by designing a differentiated putty coating direction so that the putty strip is perpendicular to the shear direction caused by the load;

[0029] 3. This application uses epoxy resin mortar with different formulations to enable different wall areas to work in two modes: rigid load-bearing and flexible adaptation, thereby improving the fatigue life of the system under complex multi-physics coupling. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the liquid cargo tank of the cryogenic liquid cargo ship described in Embodiment 1 of this application;

[0031] Figure 2 This is a schematic diagram of the arrangement structure of the side wall and epoxy resin putty described in Embodiment 1 of this application;

[0032] Figure 3 This is a schematic diagram of the corner area arrangement structure described in Embodiment 1 of this application;

[0033] Figure 4 This is a schematic diagram of the arrangement structure of epoxy resin putty in the side wall surface as described in Embodiment 1 of this application;

[0034] Figure 5 This is a schematic diagram of the arrangement structure of the epoxy resin putty on the front side as described in Embodiment 1 of this application;

[0035] Figure 6 This is a schematic diagram of the arrangement structure of the epoxy resin putty sealant described in Embodiment 1 of this application;

[0036] Figure 7 This is a schematic diagram of the arrangement structure of the fiber reinforcement layer described in Embodiment 2 of this application.

[0037] In the diagram: 1. Liquid cargo tank; 2. Insulation box; 21. Upper plywood; 22. Lower plywood; 23. Polyurethane foam block; 24. Fiber reinforcement layer; 3. Epoxy resin sealant; 4. Storage tank; 41. Side wall; 411. First wall area; 412. Second wall area; 413. Corner area; 42. Top surface; 43. Bottom surface; 44. Front; 45. Back; 5. Wedge block; 6. Epoxy resin sealant. Detailed Implementation

[0038] The technical solutions of various embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Example 1

[0040] Reference Figures 1 to 3 This embodiment discloses a cryogenic liquid cargo storage and transportation vessel. The vessel includes a liquid cargo tank 1, and a membrane enclosure system is fixed to the inner wall of the liquid cargo tank 1. The membrane enclosure system includes an insulation layer, which is formed by multiple insulation boxes 2 bonded to the liquid cargo tank 1 with epoxy resin putty 3. The insulation box 2 includes an upper plywood 21, a lower plywood 22, and a polyurethane foam block 23 sandwiched between the upper plywood 21 and the lower plywood 22. Epoxy resin putty 3 is applied between the lower plywood 22 and the liquid cargo tank 1. The membrane enclosure system forms a storage tank 4 for containing liquefied gas. The storage tank 4 has two side walls 41 arranged opposite each other along the width direction of the hull. The side walls 41 have a first wall area 411 arranged vertically and a second wall area 412 arranged inclinedly. The adjacent epoxy resin mortar 3 in the first wall area 411 and the second wall area 412 are in a discontinuous strip structure, and the spacing between adjacent epoxy resin mortar 3 in the first wall area 411 is smaller than the spacing between adjacent epoxy resin mortar 3 in the second wall area 412; the coating direction of the epoxy resin mortar 3 on the side wall 41 is parallel to the length direction of the hull; the long side of the insulation box 2 in the first wall area 411 is parallel to the coating direction of the epoxy resin mortar 3, and the short side of the insulation box 2 in the second wall area 412 is parallel to the coating direction of the epoxy resin mortar 3; the density of the polyurethane foam block 23 used in the insulation box 2 in the first wall area 411 is greater than the density of the polyurethane foam block 23 used in the insulation box 2 in the second wall area 412.

[0041] Reference Figures 1 to 3Specifically, the insulation box 2 includes an upper plywood 21, a lower plywood 22, and a polyurethane foam block 23 sandwiched between the upper plywood 21 and the lower plywood 22. The upper plywood 21 is usually made of wood, such as birch plywood, which has good strength and surface smoothness. Of course, other boards with similar properties, such as poplar plywood, can also be used. The lower plywood 22 can also be made of wood, and its function is to bond it with epoxy resin putty 3 to fix the insulation box 2 to the liquid cargo tank 1. The polyurethane foam block 23 has good thermal insulation properties. It is sandwiched between the upper plywood 21 and the lower plywood 22 to play a role in heat insulation. In some special cases, other thermal insulation materials can be used to replace the polyurethane foam block 23, such as polystyrene foam board, but the performance of polyurethane foam block 23 is more stable in low-temperature environments.

[0042] Reference Figures 1 to 3 The side walls 41 are all composed of a central elevation, an upper sloping surface, and a lower sloping surface. The upper sloping surface connects the top of the central elevation to the top surface 42 of the storage tank 4, and the lower sloping surface connects the bottom of the central elevation to the bottom surface 43 of the storage tank 4. The central elevations of the two sides are the left elevation and the right elevation, respectively. The left elevation and the right elevation are the first wall area 411, and the upper sloping surface and the lower sloping surface are the second wall area 412.

[0043] Reference Figures 1 to 3 Epoxy resin putty 3 is applied between the lower plywood 22 and the liquid cargo tank 1, serving as an adhesive and load-bearing agent. In the first wall region 411 and the second wall region 412, adjacent epoxy resin putty 3s are applied in a discontinuous strip structure. In the first wall region 411, the spacing between adjacent epoxy resin putty 3s is smaller than that in the second wall region 412. This is because the first wall region 411 bears a larger impact load from the sloshing of the liquid cargo, and a smaller spacing can provide higher bonding strength and load-bearing capacity. For example, the spacing between adjacent epoxy resin putty 3s in the first wall region 411 can be set to 80mm~105mm, while the spacing between adjacent epoxy resin putty 3s in the second wall region 412 can be set to be slightly larger, greater than the spacing in the first wall region 411.

[0044] Reference Figures 1 to 3 The epoxy resin putty 3 on the side wall 41 is coated in a direction parallel to the length of the hull; the long side of the insulation box 2 located in the first wall area 411 is parallel to the coating direction of the epoxy resin putty 3, and the short side of the insulation box 2 located in the second wall area 412 is parallel to the coating direction of the epoxy resin putty 3. This design ensures that the extension direction of the putty strip is always matched with the direction of the optimal bending stiffness of the plywood 22 under the insulation box 2 and the load transfer path, significantly improving the uniformity of stress at the bonding interface between the putty and the lower plywood 22.

[0045] Reference Figures 1 to 3The density of the polyurethane foam blocks 23 used in the insulation box 2 in the first wall area 411 is greater than that used in the insulation box 2 in the second wall area 412. The density of the polyurethane foam blocks 23 in the first wall area 411 is 150 kg / m³ to 200 kg / m³, while the density of the polyurethane foam blocks 23 in the second wall area 412 is 100 kg / m³ to 150 kg / m³. This is because the first wall area 411 bears a larger impact load, and the higher density foam has higher compressive strength and elastic modulus, which can effectively resist impact and reduce the bending deflection of the lower plywood 22. On the other hand, the second wall area 412 has a smaller load and is more dependent on insulation performance, so the lower density foam has a lower thermal conductivity, which can reduce heat loss.

[0046] Reference Figures 2 to 4 Corner zones 413 are formed between each wall of the storage tank 4. The epoxy resin putty 3 in the corner zone 413 is in the shape of a disc. Corner zones 413 are often the locations of geometric abrupt changes and stress concentrations. The disc-shaped putty has isotropic stress characteristics and can evenly bear load components from different directions, avoiding edge peeling or shear failure that may occur in the corner zone 413 of the strip-shaped putty, and significantly improving the reliability of the bonding structure in the corner zone 413.

[0047] Reference Figures 1 to 3 The epoxy resin mortar 3 used in the first wall area 411 is the first formulation mortar, and the epoxy resin mortar 3 used in the second wall area 412 is the second formulation mortar. The elastic modulus of the first formulation mortar after curing is higher than that of the second formulation mortar after curing, and the elongation at break of the first formulation mortar after curing is lower than that of the second formulation mortar after curing. The high-intensity swaying load borne by the first wall area 411 requires the mortar to have high stiffness and high shear resistance to strictly limit the displacement of the insulation box 2 under impact. The high elastic modulus mortar can efficiently transfer the load to the hull structure without excessive deformation; while the second Because the wall area 412 is inclined and close to the upper and lower corner areas 413 of the storage tank 4, the thermal stress changes are large and frequent. Using a putty with low elastic modulus and high elongation at break can absorb the displacement caused by thermal deformation like a flexible buffer layer, avoiding the putty layer itself from cracking or detaching from the tank wall due to rigid bonding. In a preferred example, the first formula putty contains 100 parts by weight of epoxy resin, 30 parts by weight of curing agent, and 150 parts by weight of rigid filler (such as quartz powder); the second formula putty contains 100 parts by weight of epoxy resin, 35 parts by weight of flexible curing agent, and 10 parts by weight of toughening agent, thereby obtaining different elastic modulus and elongation at break.

[0048] Reference Figures 1 to 3The total bonding area between the epoxy resin putty 3 and the plywood 22 under the insulation box 2 shall not be less than 25% of the bonding surface of the plywood 22 under the insulation box 2. This ratio is the minimum effective bonding area threshold obtained based on the mechanical analysis of the bonding interface and a large number of bonding strength tests. When the bonding area ratio is less than 25%, the shear stress borne by a single strip of putty will exceed the shear strength of the putty itself or the peeling strength of the wood fibers on the surface of the plywood 22. Under long-term alternating loads, the bonding interface is prone to fatigue failure. When it reaches or exceeds 25%, the bonding stress distribution generated by the putty strip can make the stress in each area of ​​the plywood 22 tend to be uniform, avoiding local stress peaks, thereby ensuring that the first wall area 411 can still maintain a reliable bonding state after experiencing all shaking conditions within the design life.

[0049] Reference Figures 4 to 5 The epoxy resin putty 3 on the top surface 42 and bottom surface 43 of the storage tank 4 is coated in a direction parallel to the length of the ship. The storage tank 4 has a front surface 44 and a back surface 45 that are arranged opposite each other along the length of the ship. The epoxy resin putty 3 on the front surface 44 and the back surface 45 is coated in a direction perpendicular to the length of the ship and parallel to the height of the ship. This differentiated coating direction design takes into account the dominant load direction of each wall surface of the storage tank 4 under the rolling and pitching motion of the ship, and maximizes the shear resistance of the putty on all walls.

[0050] Reference Figures 4 to 6 The bulkhead of the liquid cargo tank 1 is provided with wedges 5 or positioning holes for positioning the insulation box 2. Epoxy resin putty 3 is arranged to avoid the wedges 5 or positioning holes, and the gap between two insulation boxes 2 is filled with epoxy resin putty sealant 6. The insulation box 2 is installed and positioned by using wedges 5 or positioning holes. The epoxy resin putty 3 avoids the positioning structure, which prevents the putty from contaminating the positioning surface or filling the positioning holes, thus avoiding the subsequent inaccurate positioning of the insulation box 2. This ensures the installation accuracy and consistency of repeated positioning of the insulation box 2. At the same time, the epoxy resin putty sealant 6 is filled in the gap between two adjacent insulation boxes 2 to seal the gap and prevent the risk of cold brittleness caused by the leakage of low-temperature liquefied gas contacting the hull structure. Moreover, the putty forms a limited connection between adjacent insulation boxes 2, which enhances the overall cohesive force-bearing capacity of the insulation layer in the plane and prevents a single insulation box 2 from moving or rotating independently due to swaying. This further improves the structural integrity and sealing reliability of the enclosure system.

[0051] The implementation principle of this embodiment is as follows: By differentiating the layout and materials of the insulation box 2 and epoxy resin mortar 3, this embodiment fully considers the non-uniform distribution of liquid cargo sloshing impact loads on the walls of the storage tank 4. Different mortar spacing, coating direction, foam density, mortar formulation, and plywood thickness are used in different areas to achieve a precise match between structural resistance and load distribution. In high-load areas, the impact resistance and load-bearing capacity are enhanced, avoiding the problem of insufficient safety margin; in low-load areas, the waste of material performance is avoided, while the insulation performance and long-term service reliability are improved, representing a significant improvement and enhancement compared to existing technologies.

[0052] Example 2

[0053] Reference Figure 7 The difference between this embodiment and embodiment one is that the thickness of the lower plywood 22 of the insulation box 2 in the first wall area 411 is greater than the thickness of the lower plywood 22 of the insulation box 2 in the second wall area 412 or corner area 413, and the insulation box 2 in the first wall area 411 is internally embedded with a fiber reinforcement layer 24; and the embedded fiber reinforcement layer 24 can be made of materials such as glass fiber or carbon fiber mesh.

[0054] The implementation principle of this embodiment is as follows: the thickness of the lower plywood 22 in the insulation box 2 within the first wall region 411 is greater than the thickness of the lower plywood 22 in the second wall region 412 or corner region 413. Furthermore, a fiber reinforcement layer 24 is embedded inside the insulation box 2 in the first wall region 411. This is a dual reinforcement measure for the structural strength of the insulation box 2 in high-load areas. Increasing the thickness of the lower plywood 22 directly improves its flexural section modulus, enabling it to more effectively resist bending stress caused by liquid sloshing impact. The embedded fiber reinforcement layer 24, such as glass fiber or carbon fiber mesh, significantly improves the in-plane shear strength and interlaminar peel strength of the plywood, preventing plywood delamination failure under high stress cycles. Since the load on the second wall region 412 is smaller, these reinforcement measures are unnecessary, thus controlling the overall manufacturing cost while ensuring the safety of critical areas.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of this application.

Claims

1. A vessel for storing and transporting cryogenic liquid cargo, the vessel comprising a liquid cargo tank (1), the inner wall of the liquid cargo tank (1) being fixedly provided with a membrane enclosure system, the membrane enclosure system comprising an insulation layer, the insulation layer being formed by bonding multiple insulation boxes (2) to the liquid cargo tank (1) with epoxy resin putty (3), the insulation box (2) comprising an upper plywood (21), a lower plywood (22) and a polyurethane foam block (23) sandwiched between the upper plywood (21) and the lower plywood (22), the epoxy resin putty (3) being applied between the lower plywood (22) and the liquid cargo tank (1), the membrane enclosure system forming a storage tank (4) for containing liquefied gas, characterized in that, The storage tank (4) has two side walls (41) arranged opposite each other along the width of the hull. The side walls (41) have a first wall area (411) arranged vertically and a second wall area (412) arranged at an angle. The epoxy resin putty (3) in the first wall area (411) and the second wall area (412) is a discontinuous strip structure, and the spacing between adjacent epoxy resin putty (3) in the first wall area (411) is smaller than the spacing between adjacent epoxy resin putty (3) in the second wall area (412). The spacing; the epoxy resin putty (3) on the side wall (41) is coated in a direction parallel to the length of the hull; the long side of the insulation box (2) located in the first wall area (411) is parallel to the coating direction of the epoxy resin putty (3), and the short side of the insulation box (2) located in the second wall area (412) is parallel to the coating direction of the epoxy resin putty (3); the density of the polyurethane foam block (23) used in the insulation box (2) in the first wall area (411) is greater than the density of the polyurethane foam block (23) used in the insulation box (2) in the second wall area (412).

2. The cryogenic liquid cargo storage and transportation vessel according to claim 1, characterized in that, A corner area (413) is formed between each wall of the storage tank (4), and the epoxy resin putty (3) in the corner area (413) is in the shape of a disc.

3. The cryogenic liquid cargo storage and transportation vessel according to claim 1, characterized in that, The thickness of the plywood (22) under the insulation box (2) located in the first wall area (411) is greater than the thickness of the plywood (22) under the insulation box (2) located in the second wall area (412) or corner area (413).

4. The cryogenic liquid cargo storage and transportation vessel according to claim 3, characterized in that, The spacing between adjacent epoxy resin putty (3) in the first wall area (411) is 80mm~105mm; the diameter of epoxy resin putty (3) in the corner area (413) is greater than or equal to 50mm.

5. The cryogenic liquid cargo storage and transportation vessel according to claim 1, characterized in that, Each of the sidewalls (41) is composed of a central elevation, an upper slope and a lower slope. The upper slope connects the top of the central elevation to the top surface (42) of the tank (4), and the lower slope connects the bottom of the central elevation to the bottom surface (43) of the tank (4). The central elevations of the two sidewalls (41) are the left elevation and the right elevation, respectively. The left elevation and the right elevation are the first wall area (411), and the upper slope and the lower slope are the second wall area (412). The epoxy resin putty (3) on the top surface (42) and bottom surface (43) of the tank (4) is coated in a direction parallel to the length of the ship. The tank (4) has a front (44) and a back (45) arranged opposite to each other along the length of the ship. The epoxy resin putty (3) on the front (44) and the back (45) is coated in a direction perpendicular to the length of the ship and parallel to the height of the ship.

6. The cryogenic liquid cargo storage and transportation vessel according to claim 1, characterized in that, The density of the polyurethane foam block (23) in the first wall area (411) is 150kg / m³~200kg / m³, and the density of the polyurethane foam block (23) in the second wall area (412) is 100kg / m³~150kg / m³.

7. The cryogenic liquid cargo storage and transportation vessel according to claim 1, characterized in that, The epoxy resin putty (3) used in the first wall area (411) is the first formulation putty, and the epoxy resin putty (3) used in the second wall area (412) is the second formulation putty. The elastic modulus of the first formulation putty after curing is higher than that of the second formulation putty after curing, and the elongation at break of the first formulation putty after curing is lower than that of the second formulation putty after curing.

8. The cryogenic liquid cargo storage and transportation vessel according to claim 1, characterized in that, The insulation box (2) in the first wall area (411) is embedded with a fiber reinforcement layer (24).

9. The cryogenic liquid cargo storage and transportation vessel according to claim 1, characterized in that, The total bonding area between the epoxy resin putty (3) and the plywood (22) under the insulation box (2) is not less than 25% of the bonding surface of the plywood (22) under the insulation box (2).

10. The cryogenic liquid cargo storage and transportation vessel according to claim 1, characterized in that, The bulkhead of the liquid cargo tank (1) is provided with wedges (5) or positioning holes for positioning the insulation box (2); the epoxy resin putty (3) is arranged to avoid the wedges (5) or positioning holes; and the gap between the two insulation boxes (2) is filled with epoxy resin putty sealant (6).

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