Tank suitable for cryogenic service

Abstract

This invention provides a tank suitable for cryogenic service and a method of constructing the tank. The tank includes: an inner tank, a thermal insulation body, and an airtight outer shell, wherein the thermal insulation body is disposed outside the inner tank, and the outer shell is disposed outside the thermal insulation body. It also includes a connector passing through the outer shell, wherein a vacuum pump on the outside of the tank can be connected to draw air and gas from the volume between the inner tank and the outer shell, and includes an opening from the outside of the tank to the inside of the inner tank for loading and unloading fluids, wherein the inner tank in operation contains fluid, and the volume between the inner tank and the outer shell is under vacuum. The tank is characterized in that: the thermal insulation body includes a plurality of block elements arranged side-by-side on the inner tank, with gaps between the block elements; the outer shell includes a plurality of portions already joined together to cover the entire outer surface of the insulation body; wherein the portions of the outer shell covering the insulation block elements have a shape matching the shape of the insulation block elements; and, when viewed in a cross-section along the respective gaps, the portions of the outer shell covering the gaps between the block elements have an inwardly or outwardly oriented curved shape, and are flexible due to contraction or stretching of the curved shape.

Description

Technical Field

[0001] This invention relates to the storage and transport of fluids. More specifically, the invention provides a tank particularly suitable for storing and transporting cryogenic fluids, and a method for manufacturing the tank. Background Technology

[0002] The storage and transport of cryogenic fluids is challenging, especially in the lowest temperature ranges. A wide variety of gases are stored and transported at very low temperatures and are typically kept in insulated containers. One example is liquefied natural gas, which liquefies at -163°C and is usually insulated by an external porous or fibrous non-vacuum insulation layer, although vacuum insulation has also been applied to relatively small and medium-sized tanks.

[0003] In recent years, the interest and demand for storing liquid hydrogen have been increasing, posing unique challenges to insulation. At atmospheric pressure, oxygen liquefies at -183°C, nitrogen at -196°C, and hydrogen at -253°C. When these air components become liquid or solidify at the temperatures of liquefied hydrogen, the insulation performance of traditional thermal insulation based on still air deteriorates due to the liquefaction or even solidification of these air components, leading to increased thermal conductivity and near-complete failure of the thermal insulation.

[0004] There is obviously no universally accepted definition for the low temperature range, but the commonly used definition is absolute zero, which ranges from -150°C to -273°C.

[0005] For thermal insulation at low temperatures and for general enhanced thermal insulation, vacuum insulation is known to be a preferred solution. The absence of matter in a vacuum eliminates heat conduction and convection, which are the mechanisms of heat transfer. While an ideal vacuum may be difficult to achieve in practice, conditions of "near-perfect vacuum" will largely prevent heat transfer. However, significant energy transfer due to radiation will still occur, with this phenomenon depending on the fourth absolute temperature of the surfaces on opposite sides of the vacuum space. Therefore, vacuum spaces are typically filled with radiation-reducing materials such as perlite, glass bulbs, and multilayer insulators. This combination of vacuum and radiation-reducing materials is known to provide better insulation performance than a vacuum alone for most very low-temperature applications, and this is clearly also true for liquid hydrogen at 20 K.

[0006] For relatively small and medium-sized tanks, the principle of a double-shell tank can be applied, where a vacuum exists within the volume between the tank layers. Obviously, without some form of connection between the two tanks, they cannot remain separate, and inevitably, such a connection will provide thermal bridging and heat ingress. While this problem can be controlled, a larger issue is the inevitable and significant shrinkage of the inner tank at cryogenic temperatures; this means that the crucial connection between the two shell layers may fail to maintain its stability and function. For example, the thermal shrinkage rate of an inner tank containing cryogenic fluids can be as high as 7.5 mm per meter of tank; this means that for larger tanks, the problem of inner tank thermal shrinkage becomes even more pronounced. It is important to note that the loss or weakening of the connection is not only related to the spacing, but the outer tank will also be affected by external atmospheric pressure, under which the outer tank may buckle if the supports are not intact. Buckling instability of the outer shell can be a serious problem for large tanks, limiting the applicability of double-shell vacuum tanks to fairly medium-sized tanks.

[0007] Attempts have been made to address this size issue. A more recent prior art publication, in comparison to this invention, is patent US8,807,382 B1, which describes and illustrates a storage system with a flexible vacuum sheath instead of a rigid outer casing. Multiple layers of insulating material support the flexible vacuum sheath.

[0008] Some other examples of prior art include publications JP 3111658U, JP 6435517B, JPH06293290A, JP2007218317A and DE 102004015295B4.

[0009] A highly desirable objective is to provide a tank design that allows for virtually any volume and shape at an affordable cost, permits operating temperatures as low as -253°C, and provides sufficient insulation to prevent excessive internal pressure buildup from the boiling of cryogenic liquids, thus avoiding gas emissions or the need for active cooling and condensation of the vapors to reliquefy the vapors. Another important objective is to provide a vacuum insulation system that is equally effective for both small and very large tanks; that is, a tank with an insulation system that is fully scalable. Multi-dimensional scalability of the inner tank's dimensions and internal pressure can be ensured by using a so-called "lattice pressure vessel," or simply LPV, for the inner tank; particularly as described and illustrated in patent publications WO 2012 / 148154 A2 and WO2015073719 A1.

[0010] The object of this invention is to provide a can that is beneficial in terms of one or more of the above-mentioned technical effects. Invention Overview

[0011] The object of this invention is achieved by providing a tank suitable for storing and transporting fluids at cryogenic temperatures, the tank comprising:

[0012] Inner tank,

[0013] Thermal insulation, and

[0014] The outer casing is airtight.

[0015] The thermal insulation body is located on the outside of the inner tank, and the outer shell is located on the outside of the thermal insulation body.

[0016] It also includes a connector that passes through the outer casing, wherein a vacuum pump on the outside of the tank can be connected to draw air and gas from the volume between the inner pressure tank and the outer casing, and

[0017] It also includes an opening from the outside of the tank to the inside of the inner tank for loading and unloading fluids.

[0018] The inner tank in operation contains fluid, and the volume between the inner tank and the outer shell is in a vacuum state.

[0019] The distinctive feature of this jar is:

[0020] The thermal insulation body comprises several block elements arranged side by side on the inner tank, with gaps between the block elements, preferably located on the outer side of the insulation body.

[0021] The outer shell includes several portions that have been joined together to cover the entire outer surface of the insulator. The portion of the outer shell covering the insulator block element has a shape that matches the shape of the insulator block element, and when viewed in a cross section along the corresponding gap, the portion of the outer shell covering the gap between the block elements has an inward or outward oriented curved shape, and is flexible due to the contraction or stretching of the curved shape.

[0022] The present invention also provides a method for manufacturing the can of the present invention, characterized by the following steps: manufacturing or providing an inner can; manufacturing or providing an insulating block element; manufacturing or providing an opening for filling or draining fluid; manufacturing or providing a coupling for a vacuum pump; manufacturing or providing an outer shell portion; arranging the block element side by side and fastening it to the outer surface of the inner can; arranging the opening and coupling for the vacuum pump; and arranging and joining the outer shell portion together.

[0023] The present invention also provides the use of the tank of the present invention for storing and transporting cryogenic fluids or other fluids that are cold or hot relative to ambient temperature, such as fluids whose temperature differs from ambient temperature by at least 30°C.

[0024] The openings for loading and unloading fluids from the outside of the tank to the inside of the inner tank are either combined inlets and outlets or separate structures. These combined or separate structures represent the only significant thermal bridge through the tank's insulating body.

[0025] Preferred embodiments, such as those defined in the dependent claims, are referred to herein. Further preferred embodiments are described or illustrated herein.

[0026] Preferably, the gap between the insulator block elements is located on the outer side of the elements, i.e., the side of the elements facing the outer shell. The smaller gap should extend from the outer surface to the inner tank surface to avoid overlap of adjacent blocks during thermal shrinkage of the inner tank and to facilitate efficient extraction of air or gas during vacuum processes. Preferably, the inner tank is a pressure tank. Preferably, the block elements are arranged and secured to the inner tank by adhesive and / or mechanical means, with the block elements close together facing the inner tank surface. When installed at ambient temperature, there is no gap between the block elements at the interface between the inner tank and the block elements. The gap below an optional insulator cutout under the curved portion of the outer shell preferably includes the non-parallel side forming a V-shaped or U-shaped gap between the block elements, as viewed in cross-section. The gap is preferably maintained when the tank is in cryogenic service to retain flexibility and maintain a channel for vacuum suction when the temperature inside the insulator drops to a cryogenic temperature.

[0027] The curved portions of the outer shell extend outward or inward from the general outer shell surface covering the insulating block elements. As will be explained further, an empty can at ambient temperature will have the largest gap between the insulating block elements and correspondingly the largest width of the curved portions covering the gap. To ensure that all curved portions bend outward or inward along their entire length, thereby avoiding locking and high stress concentration, an initial curvature is preferably provided for all curved portions. When the can is filled with a cryogenic fluid (such as LH2 at -253°C), the inner can thermally shrinks, causing the insulating blocks and curved portions to shrink. The colder the fluid, the greater the shrinkage at the joint area between the blocks.

[0028] The curved portion, in principle, represents a "minimum energy" geometry, which can be derived from the natural buckling function when the gaps between the blocks are compressed. The simplest linear buckling form is a cosine function, the amplitude of which can be amplified to achieve flexible corrugations. Both outward and inward corrugations are feasible. The span of the corrugations and the chosen initial amplitude both depend on the specific circumstances related to the dimensions of the overall cooling and insulation blocks. This concept provides an efficient corrugation shape that minimizes the overall stress level and stress concentration in the corrugations during the thermal contraction of the main tank. Both the assumed ideal cosine function and the buckling shape generated through numerical simulation can be used. Their practical performance (e.g., the stress generated) can be determined through numerical simulation or testing for each detailed embodiment.

[0029] If the shrinkage dimension D per meter of the outer surface of the inner tank is such that, when cooled from ambient temperature to cryogenic temperature, the width of the gaps on the outward sides of the insulating blocks and the curved portions of the covering gaps are preferably significantly greater than the actual thermal shrinkage occurring across the gaps themselves. As those skilled in the art will understand, the value of D depends on the temperature difference between the ambient temperature and the cryogenic temperature at which the cryogenic fluid fills the tank. Typically, for LH2, D is up to about 7.5 mm / m for aluminum inner tanks and up to about 5 mm / m for stainless steel inner tanks. Sufficient width must be selected for the gaps on the outward sides of the insulating blocks, and sufficient width and height must be selected for the curved portions of the covering gaps to avoid unacceptable plastic strain and to obtain stress levels below specified limits according to specifications and standards.

[0030] Preferably, the corrugated shape of the flexible outer shell at the intersection of the two gaps is obtained by superimposing a cosine shape or by employing a shape generated by buckling analysis, as will be explained further.

[0031] The outer shell sections are preferably welded together, or alternatively joined in other ways, such as by brazing or bonding, but always using a joining method that ensures an airtight seal under all operating design conditions throughout the design life. For example, the operating design conditions for liquid hydrogen are +45 to -253°C. The normal target design life for such applications is 30 years. This is considered readily achievable due to low stress concentration and strain, and the fact that there will be very few thermal load cycles. Therefore, fatigue is not a critical design factor, as the inner tank will remain at or near the cryogenic temperature once filled with cryogenic fluid, due to the tank's extreme insulation properties and the fact that the required amount of cryogenic fluid is usually always maintained even when "empty." Heating and expansion of the inner tank will only occur when inspections are required, such as every five years, and possibly during servicing.

[0032] Preferably, when the inner tank in operation contains cryogenic fluid, the entire volume between the inner tank and the outer shell is under vacuum. The inlet and outlet penetrate the inner tank and the outer shell, and are therefore not located directly between the inner tank and the outer shell.

[0033] The can of the present invention preferably comprises a "grid pressure vessel" inner can, meaning that the inner can includes the same or similar internal structure as described and shown in patent publications WO2012 / 148154 A2 and WO 2015073719 A1. Therefore, for the can of the present invention, size and shape limitations are eliminated. More specifically, the "grid pressure vessel" concept eliminates size and shape limitations of the inner can, and the insulator concept of the present invention eliminates size and any shape limitations of the insulator. Furthermore, the present invention can also be applied to other shell shapes, such as cylindrical pressure vessels. Obviously, the size of a cylinder is not scalable.

[0034] The flexible, bent portions of the housing between and on the block elements can be separate portions of the pre-fastened housing portions connected to the insulating blocks. The housing portions can be applied after the insulating block unit is mounted on the inner tank surface, and the flexible, bent areas covering the gaps can be integrated portions of the housing sections. Therefore, the actual joint connections between different portions of the housing can be located away from the block joints. Consequently, potentially weaker joints are located away from the portions of the housing subjected to the highest stress levels.

[0035] The tanks of this invention (such as the specified isolated tanks) can be used to store any fluid or material, particularly if their temperature differs from the ambient temperature outside the tank, being either colder or hotter. The unique advantages offered by this invention increase with the size of the tank and the temperature difference between the contents of the tank and the ambient temperature outside the tank. However, due to the combination of excellent insulation and a design that facilitates practical and economical manufacturing, isolated tanks are, in principle, advantageous for storing and transporting any fluid with a high temperature difference relative to the ambient temperature, and are primarily intended for storing and transporting fluids at low or very cold temperatures, wherein the inner tank in operation contains fluids such as liquid hydrogen at -253°C, LH2, or any other gas or liquid requiring effective thermal insulation, particularly eliminating the liquefaction or solidification of the surrounding air.

[0036] While tanks for storing and transporting liquefied natural gas and liquid hydrogen are specifically mentioned, the invention is equally applicable to a wide variety of other cooling and cryogenic fluids, such as liquid nitrogen, liquid oxygen, liquid carbon dioxide, liquefied petroleum gas, liquid ammonia, and many types of industrial gases. Furthermore, the tanks of the invention can be used to store and / or transport thermal fluids, such as steam and superheated steam, for example in thermal batteries, as described and illustrated in International Patent Publication WO 2020 / 251373 A1. However, polymer-based insulators may need to be replaced with mineral-based insulators, and metallic materials may be replaced with high-temperature stable alloys.

[0037] The flexible, airtight joint between the blocks must possess sufficient elasticity, flexibility, and deformability to accommodate the thermal contraction and / or expansion of the inner tank, and be able to withstand an inner vacuum and at least one atmosphere of pressure from the outside without permanent deformation or damage. The flexible, airtight joint between the blocks can be a single-layer structure, wherein a thin metal layer with the joint geometry is welded to a flat portion of the outer metal layer of the block. Additional sealing can be applied to the welded area by applying a polymer or sealing tape. Other joining methods can also be applied, wherein the joint portion is connected to the flat portion by a combination of welding and sealing materials or fabrics. Alternatively, the flexible geometry of the metal skin between the blocks is formed as part of the outer skin and attached to the blocks. Thus, the joint seams between different sections of the outer skin can be positioned away from the area between the blocks, for example, at the centerline of the blocks.

[0038] The geometry of the outer casing at the flexible joint area or line between the blocks is an important part of the invention. When the inner tank shrinks due to the filling of cold fluid, the joint area or gap between adjacent blocks (also called block elements or components) will shrink significantly, meaning the outer casing will have to deform to accommodate this localized retraction or contraction at the block joint area. It is noteworthy that the flat portion of the outer casing does not undergo significant thermal deformation because the skin remains at the temperature of the surrounding outer air. Therefore, the "channel width" will narrow, and the corrugated outer casing must bend and contract accordingly.

[0039] The most critical part is that these channels meet at the intersection of four adjacent blocks. Clearly, the intersection zone cannot simply be two intersecting channels with a continuous channel geometry, as continuous channels would lock into this mechanism. Obviously, the geometry of the skin at the channel junction must allow for simultaneous contraction in two perpendicular directions. The geometry at the intersecting channels must ensure that only minimal bending energy is activated during the contraction of the inner tank. As will be shown, this principle of adopting a “natural deformation shape” provides low bending stress without high stress concentration and hot spots with significant yielding. The “minimum potential energy” geometry for beam or plate sections subjected to unidirectional contraction is a cosine function (corresponding to the initial cosine buckling form of a fixed beam); therefore, this shape or a similar shape should be applied to the contracting channel sections. The intersecting channel region requires a more complex shape to allow for simultaneous contraction in two directions. The preferred shape of the intersecting channel can be a cosine function superimposed on the cosine geometry of the intersecting channel. This will be explained in more detail later. A subsequent variation of this principle is to numerically generate the geometry of the junction zone by using the buckling shape obtained from the analysis of large displacement structures through the finite element method or similar computer simulation methods.

[0040] The channel geometry of the outer skin layer can point inward toward the inner tank, or it can point outward away from the tank. Both options are feasible and are included in this invention. When the channels point inward, the atmospheric pressure on the skin layer, which is below vacuum, largely causes membrane tension in the channel region. Alternatively, when this type of corrugation points outward, the pressure difference largely causes membrane compression in the channel region. Structurally, the first may be preferred; however, when it comes to actual production, including welding the skin layer regions together, outward-pointing corrugations may also have some advantages.

[0041] It should also be noted that the proposed “smooth” cosine-type geometry of the corrugations implies moderate plastic deformation during the initial forming of the flat sheet metal. The smoothness of the buckling function also implies smooth plastic bending deformation without “knots” exhibiting extreme plastic strain. The proposed corrugation geometry is clearly advantageous compared to the current corrugation geometries used in LNG membrane tanks, where the corrugations exhibit sharp bends, wrinkles, and knots. In this case, the plastic strain during the initial forming of the corrugations would be very significant, and equally problematic is the thermal deformation, strain, and further significant plasticization that occurs during operation due to temperature variations. These geometry-dependent mechanisms present in membrane tanks currently used in the maritime industry can lead to significant localized weakening of the skin material, posing a risk of cracking and gas leakage. Figure 1 The diagram illustrates prior art, showing a typical corrugated membrane used in LNG cargo tanks. Note the extensive deformation zone at the intersection of the two corrugations, resulting in extreme plastic strain and "knots," which in turn lead to very high stress concentrations during thermal shrinkage.

[0042] The present invention aims to greatly reduce these problems by using a smooth shape of corrugations that adapts to the compression of the outer skin caused by the shrinkage of the inner can.

[0043] The inner tank is preferably a pressure tank, meaning that the pressure inside the tank can be significantly higher than atmospheric pressure, for example, up to 20 times or even higher. An inner tank with overpressure capability allows the increased gas pressure to balance the increased temperature from the heat intake, thus avoiding the need to regulate gas pressure by releasing gas from the tank and / or by having to reliquefy the evaporated gas. This method of containing gas by compensating for pressure is particularly useful for liquid hydrogen, a lightweight and cost-effective energy carrier.

[0044] The inner tank and materials adjacent to it must be made of materials that can withstand operating temperatures (such as cryogenic temperatures) without becoming brittle. Austenitic stainless steel alloys maintain toughness at extremely low temperatures, while other weldable metals (such as many aluminum alloys) are suitable for use at very low temperatures. The outer shell or skin is generally not affected by cryogenic temperatures; however, stainless steel and aluminum may still be preferred due to their reflective properties and resistance to degradation. These materials also help prevent brittle cracking should cryogenic fluids accidentally leak from the inner tank.

[0045] The volume between the pressure vessel and the outer shell is a vacuum, meaning the pressure is lower than atmospheric pressure, preferably much lower, such as 0.01:0.001 or 0.0001 atmospheres or lower. Clearly, the lower the pressure, the better the thermal insulation.

[0046] Unlike vacuum insulated tanks with rigid outer shells, the layout and geometry of the vacuum insulated system of this invention can be used with tanks of any size and shape. The size of the insulated blocks, and therefore the size of the corrugated grid pattern, depends primarily on the extent to which the inner tank shrinks with cooling and pressurization, rather than on the size of the tank itself. As will be understood, this independence of tank size arises from the fact that compensation for the shrinkage of the inner tank should be applied at the local level rather than the overall tank size level. The typical size of each insulated block and the corresponding corrugation distance in either of the two surface directions can range from 0.25 meters to 2 meters. For example, a 6 mm shrinkage per meter of the inner tank means that the corrugations around a 1-meter block will have to accommodate a shrinkage of approximately 6 mm across the corrugations and in both directions at the corrugation intersections. It is understood that the ability to meet specific shrinkage requirements depends on key design parameters, such as the size of the gap at the outer plane between the blocks that determines the width of the corrugations, the amplitude of the corrugations, and the thickness of the corrugated skin. The uniqueness of the current vacuum insulated concept stems from the fact that it functions equally well independent of tank size, and that the cost and amount of installation work are proportional to the total surface area of ​​the tank. This is mainly different from the double-shell type vacuum insulator mentioned earlier. For the double-shell type vacuum insulator, due to strength requirements, the strength of the outer shell (sheath) increases significantly with size.

[0047] The can of the present invention includes a novel method for arranging vacuum insulators based on the principle of connecting a flexible outer barrier to a load-bearing porous insulator using a block-type insulator geometry, wherein the blocks are arranged together with gaps between them, and contraction and expansion are addressed through flexible joints between outer skin layers on the outer surfaces of the insulator block elements. The can can virtually have any shape and size because the shrinkage problem is locally addressed by an insulator layer adapted to the geometry of the inner can without introducing discrete thermal bridges. The block elements cover the entire outer surface of the inner can with only small gaps between them, wherein each block on the inner side has a shape or curvature perfectly consistent with the surface geometry of the inner can, and the shape on the outer side conforms to the inner side and selected thickness of the insulator layer.

[0048] The specific material chosen for the insulation block may depend on the application, taking into account internal and external temperatures, insulation requirements, shrinkage flexibility, and the ability to easily vent air or gas from the inside of the insulation body. Another requirement is that the vacuum insulation block must be able to transfer the pressure of the outside air to the inner tank. Further material requirements may relate to creep resistance under sustained pressure, mechanical and chemical stability, and consistency in adhesion or various forms of mechanical attachment. Several fibrous and porous materials exist that can meet these requirements, such as those used for LNG tank insulation. Commonly used materials in this category include PUF (polyurethane foam) and R-PUF (reinforced PUF).

[0049] The bulk geometry of the vacuum insulation layer can be produced in either of two ways. First, the insulation block can be entirely prefabricated, its shape conforming to its position on the surface of the inner tank. This shape can be obtained by casting in a mold or by shaping and grinding the insulation block into the specific geometry of the intended location. Attachment to the surface can be achieved by mechanical attachment methods and / or adhesive bonding. Prefabricated insulation blocks can be produced with the surface skin fully attached to the block. In this case, the gap area between the blocks must be covered with additional corrugated skin strips, which are welded and / or adhesively bonded to the prefabricated surface skin of the block. Importantly, the corrugated connection and weld between the block and its outer skin must have sufficient strength to withstand the pressure and forces generated by the shrinkage of the inner tank and to be leak-proof. Alternatively, the surface skin can be produced directly as a corrugated plate and applied to the insulation block (initially without a skin), wherein the seam between adjacent plates is preferably located at the centerline of the block's surface. This typically results in a reduction in weld length and thus offers several advantages. Special measures can be taken to protect the insulating material from the heat generated during welding.

[0050] An alternative to using prefabricated insulator blocks with foam-type insulators is to directly spray the insulator layer by layer onto the outer surface of the inner tank. This is a known and accepted method for applications such as LNG. However, the use of a block design remains necessary because it is necessary to effectively vent the insulator layers and to reduce insulator stress due to inner tank shrinkage. This can be best accomplished by carving, grinding, or sawing regular deep channels, preferably down to the surface of the inner tank, so that a continuous system of air venting channels spans the entire surface area of ​​the inner tank. Clearly, this approach provides a block insulator geometry consistent with the present invention; the main difference from prefabricated blocks is that the blocks are formed after the insulator has been applied to the tank. Porous insulators (such as various forms of PUF) have a higher coefficient of thermal expansion than steel or aluminum. For this reason, it is preferable that the gaps between the blocks are wide enough so that the gaps do not close when the inner tank shrinks due to cooling. However, since open gaps provide heat transfer through radiation of the open space, it is also desirable not to make the initial gaps wider than necessary to prevent contact or closure between the blocks under the outer shell. When the corrugations are oriented inward, the formation of these gaps should also take into account the space required by the corrugations.

[0051] As described here, spraying onto the insulating layer does not produce a perfectly smooth external polished surface. Therefore, it is necessary to flatten and smooth the outer surface of the insulating body before the corrugated surface skin is applied. This can be accomplished by grinding and / or applying a refill material to the surface. After this process, the corrugated surface skin sheet can be attached to the insulating block and welded together, as described for prefabricated insulating blocks without a pre-attached surface skin.

[0052] As mentioned above, it is important that the gaps between the insulation blocks do not close due to the thermal contraction of the inner can. Furthermore, when the corrugations point inward, these gaps must be widened by grooves near the location of the surface corrugations; this is to ensure that the shrinking corrugations never cause adjacent insulation blocks to come into direct contact. The actual geometry of the grooves in the insulation layer may not be very important, as long as the gap does not close during contraction; for example, U-shaped, V-shaped, or other shapes can be used for the initial gaps between the blocks. When the corrugations point outward from the surface of the flexible shell, corrugated grooves may not be necessary.

[0053] As previously stated, the outer shell panels must be connected to their adjacent bodies by welding, or alternatively by other means, to ensure a completely hermetically tight outer shell layer. When this means welding, a problem arises because the high-temperature heat generated during welding will be locally generated within the skin, and this heating may damage the underlying insulating material. Two simple methods can be used to address this problem. First, the insulating blocks can be protected with material strips that are themselves heat-resistant and significantly reduce heat transfer to the underlying insulating blocks at the weld location. An alternative method is to carve small grooves into the insulating blocks at the weld location so that there is no direct contact between the heated metal and the insulating material. These grooves must be wide enough to prevent welding heat damage through heat conduction through the skin, and not wider than the area across which the skin can cross the groove without excessive stress. Therefore, two types of grooves can be applied to the vacuum insulating system of this invention: (1) corrugated grooves to accommodate inward corrugation; and (2) welded grooves to prevent damage to the insulating blocks from the heat generated during welding. Thermal protection strips are an alternative to the second type of groove.

[0054] A very beneficial effect of the can insulation concept of the present invention is that the problem of thermal shrinkage as the can size increases is solved, there is no significant thermal bridging, and the only source of heat conduction is the porous insulation block itself.

[0055] The insulator is made of a porous material. Preferably, all pores (meaning all volumes filled with air or gas) are interconnected. Because the porous material is not airtight, vacuum purging removes trapped air or gas from the pores within the insulator, leaving no significant amount of trapped air or gas inside; this ensures very good insulation performance. Effective purging of air or gas prevents the gas within the pores from solidifying under extremely low temperatures in the inner tank (e.g., when filled with a fluid such as liquid hydrogen). This porosity is commonly referred to as open porosity.

[0056] The can of the present invention includes channel-like corrugations in the outer skin layer, which are arranged in places where gaps and grooves between isolating block elements form shrinkage spaces, including a special corrugation geometry at the locations where the corrugations intersect, wherein the channel-like corrugations are shaped to maintain and accommodate shrinkage between isolating block elements caused by thermal shrinkage of the inner can containing cold or cryogenic fluid, and wherein the corrugations of the outer flexible shell always maintain their airtightness, acting as a barrier between external air pressure and the vacuum space between the outer shell and the inner can.

[0057] Typical bulk dimensions can range from 0.25 meters to 2.5 meters in any direction along the shell surface. The chosen size depends on specific thermal and mechanical conditions and, to some extent, on the size of the tank. In specialized applications, the dimensions of the bulk elements, and therefore the distances between the corrugations, may even exceed these limitations. In short, the size and geometry of the bulk elements, as well as the dimensions of the corrugations, can depend on the geometry of the inner tank, the properties of the materials used, temperature variations, tank support conditions, and other practical considerations. The efficiency of the evacuation or vacuuming process may also be another consideration, as very large bulk elements may require a longer time to reach the required vacuum conditions compared to smaller bulk elements.

[0058] Preferably, the gaps between the block components form open spaces between the blocks that do not close during cooling and prevent the blocks from interfering with the corrugations at any time during operation.

[0059] The block components must be securely attached to the inner tank in a safe and consistent manner; this can be achieved in several ways. Adhesive insulation materials and direct spraying of insulation materials can be used. However, mechanical attachment can also be chosen to firmly hold the insulation block against the inner tank. One such method is to first attach or weld guide rails to the surface of the inner tank in a pattern that perfectly corresponds to the coverage area of ​​the insulation block against the inner tank. With such guide rails in place, the insulation block can be correctly positioned on the surface of the inner tank, and the insulation block can be held in place by a connector between the guide rails and the insulation block, for example, by inserting connecting pins or other attachment devices into the insulation material. This mechanical fastening device can be made of a material with low thermal conductivity. It is worth noting that when a vacuum is applied, the insulation block will also be firmly pressed against the inner tank by the external air pressure. Thus, the external air pressure is transmitted to the inner tank through the insulation block across the vacuum layer.

[0060] The tank insulators are arranged together as block elements under the airtight outer skin and above / outside the inner tank. They must have a permissible compressive strength of at least 0.1 MPa (corresponding to one atmosphere) and sufficient elastic stiffness to ensure that stress and deformation remain within acceptable ranges throughout the entire operating temperature range (e.g., +45°C to -253°C).

[0061] The flexible corrugations have a defined shape that minimizes stress within the corrugated skin and allows for actual contraction and expansion of the gaps between the blocks during operation. The skin temperature is always very similar to the ambient temperature; however, the inner tank may be subjected to extreme cooling, such as -253°C from liquid hydrogen.

[0062] The primary objective of this invention is to provide a monolithic isolation tank solution capable of containing extremely cold fluids such as liquid hydrogen and liquid nitrogen. It is also clear that current modular, block-type isolation systems offer an attractive alternative for the thermal isolation of tanks containing other types of fluids requiring thermal isolation, such as liquefied natural gas, liquefied petroleum gas, cooled and pressurized carbon dioxide, etc.

[0063] The tanks of the present invention can also be mobile tanks, such as fuel tanks for drones, airplanes, vehicles, trains, or ships; in such applications, the flexibility and low weight of the vacuum-insulated tanks of the present invention in terms of shape and size are very important. When storing fluids such as liquid hydrogen, the modular scalability of the present invention and the fact that the tank shape can be, but does not include, cylindrical or spherical shapes are particularly important, because the overall volumetric efficiency of storage within one or more tanks becomes extremely important due to the very low energy density of liquid hydrogen per unit volume. Brief description of the attached diagram

[0064] Figure 1 The corrugated pattern used in many current thermal insulation membrane tanks is shown.

[0065] Figure 2 A conventional method for vacuum isolation of pressure vessels with a double-shell design is shown.

[0066] Figure 3 A vacuum isolation canister system according to the present invention is shown.

[0067] Figure 4 The concept of the block element is shown in more detail.

[0068] Figure 5 This demonstrates how the tank system contracts during cooling, and how this contraction is compensated for in the corrugated area of ​​the outer membrane.

[0069] Figure 6 This illustrates how bulk elements can be positioned and attached to the surface of a can using mechanical means.

[0070] Figure 7 The development of corrugated geometry is shown, which can be derived from the buckling patterns of beams and plates.

[0071] Figure 8 The evolution of the corrugated geometry at the intersection between the intersecting corrugated lines is shown.

[0072] Figure 9 An example of a wavy geometry generated by computer simulation and computer graphics is shown.

[0073] Figure 10 An example of the application of the present invention in a low-temperature grid pressure vessel is shown. Detailed description of the invention

[0074] Addressing the issue of thermal contraction or expansion in multi-barrier insulation systems typically employs some form of geometric corrugation. This corrugation allows the flexible membrane barrier to deform due to temperature variations on different sides of the insulation. A typical example of addressing different thermal conditions and deformation is the current design concept for thermally insulated tanks used to store cooled or cryogenic fluids, such as liquefied natural gas (LNG). In the case of membrane cargo tanks used for transporting LNG on ships, the ship structure itself provides the load-bearing support structure, while the cryogenic fluid is kept isolated and separated from this structure by a thermally insulating layer with sufficient thermal insulation capacity and strength, as well as a leak-proof membrane that resists the internal fluids. For safety reasons, regulations may also require a secondary leak-proof barrier inside the insulation layer. A fundamental problem arises when the membrane barrier resisting the cold fluid undergoes significant thermal contraction, while the tank structure, as an integrated part of the ship, does not. In cases of significant thermal contraction, the flat membrane can rupture noticeably due to thermal contraction and tension. This problem is typically addressed by providing an initially flat membrane with geometric corrugations, so that the corrugated areas cope with contraction through bending within the corrugations. What makes this problem difficult is that thermal shrinkage naturally occurs in both directions of the membrane, which requires the corrugations to also be oriented in both directions. Inevitably, there will be intersections of corrugations, meaning that the corrugations cannot be continuous but must "break" at these intersections to fully accommodate two-dimensional shrinkage. Figure 1 This illustrates a typical example of how current practices address the problem of corrugation convergence. In addition to the basic membrane plane 10, there are corrugations 11 in one direction and slightly larger corrugations 12 in the perpendicular direction. The “break” of the converging corrugations is accomplished by providing additional folds or “knots” 13 and 14 perpendicular to the length directions of the two corrugations, such that each of the folds or “knots” 13 and 14 can also contract in its own length direction. It can be seen that the corrugations have several rather sharp bends, implying significant localized plastic strain during the geometry formation process of the corrugation pattern. Clearly, additional thermally generated stresses will occur during operation due to the actual thermal contraction of the membrane. The dual-channel geometry with double-folded knots implies very rigid structural regions, which often generate strong stress concentrations or “hot spots” that may exceed the normal acceptable stress levels of the particular material used. This invention defines a significantly different corrugation and convergence geometry that greatly reduces plastic strain during geometry formation and ensures acceptable stresses due to thermal deformation during operation.

[0075] When a vacuum is used to isolate a hot vessel, special requirements arise for the connections. For example... Figure 2As shown in diagram a, a common method for vacuum-insulated containers not according to the invention is to provide an external, airtight, rigid "shroud" or shell 21 for the inner housing 20, such that the space 22 between the two shells can be emptied for thermal insulation purposes. There are typically some structural connections 23 between the inner shell 20 and the outer shell 21; these connections 23 can have various shapes and stiffnesses and are shown only in principle here. The container 20 for cooled, liquid fluid must be designed as a pressure vessel because heat ingress is unavoidable, and the internal pressure will increase accordingly due to the transition from liquid 24 to gas 25. The outer shell is subjected to external pressure due to atmospheric pressure on one side and a near-perfect vacuum on the other side 22, and these must be taken into account in the design. The external pressure on the shell also means that it may be susceptible to structural instability and buckling. As shown, the outer shell 21 can be partially supported to the inner shell by some kind of connection 23 that ensures the distance between the shells and a certain degree of structural support for the outer shell. It should also be noted that the connection 23 between the two shells will inherently result in thermal bridging. Unfortunately, structural compatibility and cross-support between the shells become challenging when the containment tank shrinks significantly due to the filling of cold fluid 24 and the inner shell 20 shrinks accordingly due to cooling. In practice, this means that buckling or stability problems increase with the actual size of the vacuum isolation tank, as buckling is highly dependent on the overall tank size, and the distance difference or incompatibility between the two layers is proportional to the actual tank size. To some extent, this problem can be addressed by constructing a very robust and rigid outer shell that can withstand external pressure and the shrinkage of the inner tank, while stability and buckling problems increase significantly with increasing shell size. Instability and buckling problems are, in principle, on the right side. Figure 2 As shown in b, the outer shell is partially forced to follow the contraction of the inner shell, and the outer shell buckles due to external pressure. Alternatively, the connector 23 can be flexible, while the outer shell may suffer from an overall buckling mode. For the reasons described above, the size of double-shell vacuum insulation vessels has been limited to a few hundred cubic meters until now. The present invention proposes a different method of vacuum insulation in which the outer shell is replaced by a modular block concept having a corrugated, highly flexible membrane or "skin" on the outside supported by a porous insulator in the block within the vacuum space.

[0076] Figure 3The concept of the invention is illustrated. 30 represents any type of container system, such as cylindrical, spherical, gridded pressure vessels, or any type of pressurized or unpressurized prismatic or other shaped container. The modular vacuum isolation system consists of isolation blocks 31 covering the entire surface of the canister. Thin, leak-proof corrugated membranes 32 and 33 are present, which, together with the isolation blocks, cover the entire outer surface of the canister, thus forming a secondary shell. Corrugations 33 are an important part of the concept because the main canister 30 will significantly shrink when filled with cryogenic fluid. Also significant is that the isolation blocks are separated by open spaces 34, which serve two main purposes: (1) they prevent the isolation blocks from squeezing against each other when the main canister shrinks due to cooling, and (2) during vacuum processes, they serve as air venting channels for the entire isolation layer covering the top of the canister. Obviously, the pattern of these gaps corresponds to the pattern of the isolation blocks. Figure 3 The diagram also shows a cold liquid 35 inside the tank and a gaseous portion 36 on top of the cold liquid 35. Piping systems 37 and 38 are also present, enabling controlled fluid filling and venting from the outside. Pipe 39 represents the connection between the air venting channel 34 within the insulator and an external vacuum pump system. The internal pressure within the tank 30 corresponds to the vapor pressure, which in turn depends on the degree of filling and the actual fluid temperature. Additionally, there are gravitational and dynamic pressure components. The most important aspect is achieving the best possible thermal insulation to keep the accumulated temperature and pressure within acceptable limits. Therefore, the purpose of a vacuum insulator is to achieve the best possible thermal insulation.

[0077] The corrugated membrane covering the entire outer surface of the covered tank system is similar to that of cryogenic membrane tanks, which are commonly used in LNG containers and combined with... Figure 1 An overview has been provided. The membrane in this laterally supported tank provides a direct barrier against leakage of the cryogenic fluid inside, and it is this membrane barrier that will thermally contract due to the cooling of the cryogenic fluid inside. This contraction of the metallic membrane results in stretching of the membrane, particularly across the corrugations. In this invention, the principle is "opposite," because the fluid is held in place, the structural vessel contracts, and the membrane maintains a relatively constant temperature of the surrounding air or gas. The contraction of the robust inner tank (typically a pressure vessel) forces the insulator and membrane together, causing the corrugations to be compressed rather than stretched, as in the case of an inner membrane tank. As will be outlined later, a major contribution of this current innovation also lies in the special geometry developed for the corrugations, which results in a significant reduction in the plastic strain forming of the corrugated membrane and a significant reduction in the elastic stress during thermal deformation.

[0078] Figure 4 a and Figure 4 b provides a more detailed explanation of two versions of the current bulk vacuum isolation concept. 30 is as follows: Figure 3The outer shell surface of the fluid container. Assuming significant cooling of the tank with fluid inside, the tank surface will shrink accordingly, consistent with the thermal properties of the tank material and the forced temperature reduction. For austenitic stainless steel, with liquid hydrogen inside the tank at -253°C, the shrinkage is approximately 4.7 mm / m in length from +20 to -253°C. As shown in more detail, the load-bearing element of the isolation system consists of porous or fibrous lightweight isolation blocks 31, which are fixed to the surface of the container 30 by mechanical attachment and / or adhesive attachment; this arrangement will be described later. The block material must be sufficiently open and porous so that air or gas initially trapped in the isolation can be completely evacuated as part of a vacuuming procedure. These blocks are separated by initial gaps 34. The shape and width of these gaps must ensure that they do not close during the cooling and thermal shrinkage of the fluid container 30 to avoid overlap, but rather remain open channels to achieve and maintain a vacuum around the entire tank. Therefore, the size and shape of these gaps depend not only on the degree of container shrinkage but also on the actual size of the block. Examples of block sizes can range from 0.5 meters to 2.5 meters, while other sizes are also feasible. Typical thicknesses of the insulating blocks can be 0.1 to 0.5 meters or even 1 meter, while other thicknesses are also possible. Note that the insulating blocks are flexible and can accommodate the same shrinkage at the can surface as the container, while the outer portion of the block remains relatively undeformed, undergoing only minor changes due to thermal variations in the surrounding gas or air.

[0079] Achieving a vacuum requires a completely sealed vacuum space, with the outer flexible shell remaining intact and undamaged during operation. This is achieved by applying a sealing membrane to the outside of the insulating blocks, which accommodates the overall thermal contraction of the inner tank. Corrugations across the open gaps between the blocks are crucial for handling tank shrinkage. Figure 4 a shows the outward ripples in more detail, while Figure 4b illustrates an alternative inward corrugation 40. Both solutions are perfectly feasible and function in essentially the same way during tank shrinkage. The membrane is also subjected to external pressure caused by atmospheric pressure on the outside and vacuum within the insulating layer; here, it is approximately 1 bar or 0.1 MPa. In case 4a, the pressure acts on the outward arched geometry 33, which results in a small "push" across the gap by the membrane stress component during compression. For case 4b, the difference is that the pressure acts on the inward "hammock" geometry 40, which results in a small "pull" across the gap by the membrane stress component during tension. Both principles work. The advantage of outward corrugation is that it makes the necessary welding of the membrane sections easier and more readily achievable compared to the inward case. Inward corrugation requires less space and is less susceptible to mechanical damage from external sources. Inward corrugation may also require modification of the geometry of the gap between the blocks with additional grooves 41 to provide space for the corrugation, thereby avoiding direct contact with the insulating blocks.

[0080] Figure 5 The purpose is to explain in more detail how the invention works. Figure 5 Figure a shows an outer view of a surface cross-section with a 3×3 insulating block pattern before cooling occurs in the main tank. Line 50 can be considered as a system line marked on the surface of the inner container before cooling. The distance between the system lines is a in one direction and b in the other. The figure also shows the film region 51 between the corrugations and the corrugated pattern 52 (oriented inward or outward) between the blocks before cooling. The size of the contact area is c in one direction and d in the other. Therefore, the span of the corrugations is e=ac in one direction and f=bd in the other. Figure 5 b shows the situation after thermal cooling, where the distance between the system lines 50 on the inner tank has been reduced to that in a. T and b T The actual shrinkage depends on the temperature change after the tank cools down. And the secant modulus of thermal expansion of the can, therefore

[0081]

[0082] It should be noted that this is relative to the initial temperature of 20°C before cooling; for example, for liquid hydrogen, the cooling temperature is -273°C. The value is negative. The outer membrane will not experience significant self-thermal shrinkage because it remains at its current external temperature. This means that the thermal shrinkage of the inner tank must be regulated by the mechanical shrinkage within the corrugated area shown in the shaded region of the diagram. Therefore, the span e of the corrugated area after cooling... T and f T become:

[0083]

[0084] The actual mechanical contraction experienced by the corrugations is:

[0085]

[0086] The contraction caused by the corrugations is proportional to the distances a and b between the system lines 50. The sizes of the corrugation spans e and f must be chosen based on mechanical feasibility, which in turn depends primarily on the actual corrugation design. Choosing larger distances a and b means fewer corrugations and welding, and a cheaper solution. Numerical simulations show that a distance of approximately 2 meters between corrugations is feasible for this invention; this is more than... Figure 1 The corrugated design of the current type shown is approximately ten times larger. The side dimensions of the typical block size, represented by a and b, are preferably in the range of 0.25 to 2 meters, but smaller sizes are possible, and larger sizes are also possible, especially for applications with requirements lower than LH2. The corresponding gap sizes are preferably wide enough to always maintain an open gap, meaning that the span of the curved section or the gap sizes e and f are preferably greater than the corresponding strain. and ,in and Both are negative. The gap g and the corrugation span are not necessarily the same. However, if g a and g b This represents the initial gap in two directions. The condition for the gap to be non-closed is:

[0087]

[0088] As for the curved portion and its width, the increment is negative.

[0089] Regarding the width of the curved section, and taking into consideration... and The absolute value of e is preferably at least 2. or even more preferably at least 3 Or 5 However, preferably not wider than 8 Or 10 Or 15 Similarly, f is preferably at least 2. More preferably at least 3 Or 5 However, preferably not wider than 8 Or 10 Or 15 The curved portion preferably has an initial height of at least 0.5. and 0.5 To ensure a consistent bending direction. Since the outer shell will essentially remain stationary for years, and the inner tank will be kept at low temperatures, there are no specific restrictions on the minimum or maximum width of the gaps and / or bends, as even plastically strained or very wide bends will be airtight. Maintaining open gaps is preferred to facilitate the creation of a vacuum within the insulation and to prevent plastic strain in the bends, while avoiding very wide gaps is preferred to reduce the ingress of radiated heat and to avoid questions about the robustness of the outer shell.

[0090] There are two main ways to implement the current barrier block system. First, the block can be completely prefabricated, with or without an outer membrane layer. The barrier block can be made as a single layer or by bonding multiple barrier layers together. The external geometry must be dimensionally precise, which may require precise cutting or grinding of the surfaces. Attachment to the surface of container 30 can be achieved through a combination of mechanical fastening and adhesive bonding. Figure 6 Example a is shown in which a prefabricated insulating block 60 is attached to the inner housing by a mechanical fastening device 62 connected to a guide rail 61, which is already in place. Figure 5 The system line 50 shown is welded to the surface of the container 30 at precise locations. These protruding guide rails or guide rail segments can thus be used for the precise positioning of the insulating block 60. Equally important, as shown, the guide rail 61 also provides a mechanical attachment point between the insulating block and the surface of the container 30. In the case shown, there is an extension 63 on the guide rail 61, and a connection exists between the end of this extension and the nail 62 inserted into the insulating block. Fastening is accomplished by securely attaching the extension 63 to the top of the nail 62 and the guide rail 61, thereby ensuring that the block will be mechanically locked in place. The material used for the attachment should meet acceptable thermal properties and strength requirements. Other block fastening solutions are also feasible.

[0091] Another alternative to using prefabricated blocks is to continuously spray the entire surface of the container layer by layer. Insulation body 64 has the required properties, see [link to relevant documentation]. Figure 6 b. In addition, in this case, besides the chemical bonding that occurs between the container surface and the sprayed insulator, there may be mechanical attachments or anchors 65 fastened to the container surface to ensure mechanical anchoring. After the insulator is laid, the required gaps between the blocks 66 can be sculpted, cut, or sawn. Figure 6 b illustrates the situation where this is done, including the additional space 67 that can accommodate the inward corrugations.

[0092] As mentioned above, the mechanical contraction of the outer membrane caused by the cooling of the containment tank must be absorbed by the membrane corrugations covering the gaps between the blocks. The basis for the optimal possible shape of the corrugations can be found in the geometry that generates the least possible potential energy during contraction, which implies the minimum possible deformation stress. It will be recognized that a fixed beam subjected to axial load or equivalent forced shortening will buckle into a geometry defined by a mathematical cosine function. For stability problems, this solution can be derived from the beam equations using the principle of minimum potential energy. Therefore, the cosine function is the shape that causes the least possible accumulation of stress within the fixed beam during buckling. This fact leads to the conclusion that the cosine function may also be a very good geometry for membrane corrugations, as it represents the minimum energy condition for buckling or compression of a thin plate spanning the gaps between the blocks. Figure 7 a shows a thin, elastic plate 70 having a fixed support side 71 that bears an end load 72. Figure 7 b also correspondingly shows the finite displacement at end 74. The resulting elastic buckling shape 73. In the case of only small displacements, the buckling shape is an exact cosine function in both cases. Although the cosine function is only applicable to infinitesimal deformations, it can be easily scaled to any span 75 and amplitude 76 chosen for the corrugation. Numerical stress calculations of the membrane deformation also confirm that the amplified cosine function is very well-defined as the initial corrugation shape. Furthermore, the principle of using buckling shapes for corrugations can be easily extended by utilizing more advanced buckling shapes that consider large displacement effects. Instead of using simple cosine functions, preferred shapes can be generated through structural computer simulations considering large displacement effects; such shapes have been shown to perform better than small-deformation cosines. Large-displacement buckling shapes can also be scaled according to the desired span 75 and amplitude 76 of the corrugation. Therefore, Figure 7 b can also represent the so-called nonlinear buckling shape. Figure 7 c indicates that, considering the geometric changes caused by the lateral pressure 77 in addition to the large displacement effect, it is also feasible to generate a corrugated shape 78. The figure shows the case of inward corrugation 78; however, the method defined here is equally applicable to both inward and outward corrugations.

[0093] Although the method for deriving the corrugated shape for the membrane-side junctions between blocks is straight, extending these channel shapes forward to the cross corrugations will not work because the cross corrugations will be completely locked at these points for contraction. See also Figure 5 This problem is solved by a further extension of the present invention’s current buckling shape method. Figure 8 The area between the two intersecting corrugations 80 and 81 is shown. Specifically, Figure 8 a shows from the outside according to Figure 5The system line 50 shown has two intersecting corrugations. The key to generating the lowest possible stress is to avoid geometric knots or hard spots, so the corners at the intersecting corrugations are rounded with a radius of curvature R of 82. Figure 8 Figure b shows the initial buckling cross-sectional geometry 83 of the corrugated membrane at a location far from the junction area, for example at cross-sectional cuts AA and BB. The figure also shows the corrugation span 84, the initial corrugation height h1 as shown in 85, the bottom support from the insulating block 86, and the span e1 of the corrugations between the insulating blocks, as shown in 87. Figure 88 shows the apex line of the straight corrugations located above the system line 50. Figure 8 c and Figure 8 Figure d illustrates the key to avoiding commencing corrugation locking. Instead of a direct continuation of the top of corrugation 88 as shown by dashed line 89, an "additional buckling" 90 with an additional height h2 as shown by 91 is superimposed at the system line of the commencing section. The flexibility provided by this superimposed buckling with a length e2 as shown by 92 allows the commencing section to... Figure 5 The system shown in b contracts along the line direction and diagonally. Figure 8 Figure d shows further definition of the geometry of the junction. Figure 8 Figure d shows the membrane geometry 93 along the diagonal cuts EE and FF, where the span 95 is e3 and the corrugation height 94 is the sum of h1 and h2. Note that e2 and e3 are direct functions of the choices e1 and R. Figure 8 b、 Figure 8 c. Figure 8 The ripple geometry of the membrane ripples between the lines shown in d can be easily generated by a function smoothing procedure, which is readily available and used in computer-aided design and computer graphics.

[0094] Figure 8 The corrugated geometry shown can be based on a simple cosine function, or by using more advanced large-displacement buckling functions, including applying lateral pressure during geometry generation. Further advancements include generating two-dimensional plate buckling shapes through numerical, linear, or nonlinear plate buckling simulations (e.g., using the finite element method). The loading conditions in such simulations correspond to… Figure 5 The contraction and buckling shown in figure b. Numerical simulations and tests demonstrate that the proposed method is effective.

[0095] Figure 9 An example of a membrane corrugation geometry generated using the method described herein is shown. The excellent performance of this corrugation has been confirmed by extensive nonlinear finite element analysis, demonstrating a good ability to absorb shrinkage between insulating blocks and a smooth stress level without severe “hot spots.”

[0096] Clearly, pressure vessels always include single-curved or double-curved surface areas to complete a full three-dimensional outer shell. Figure 4 and Figure 5 The block elements shown can be readily adopted with curved geometries, either by prefabricating blocks with curved geometries or, more simply, by spraying the insulator and then carving gaps between the block elements. In particular, the current modular vacuum insulator solution offers opportunities for vacuum insulators of ultra-large-sized containers; this is significant because such technology did not exist previously. As previously mentioned, grid pressure vessels (LPVs) are uniquely scalable in size, and the combination of LPVs with the block-type vacuum insulator solution of this invention opens doors to very important applications. Figure 10 The combination of the main prismatic LPV with rounded corners 100 and the isolation system of the present invention is shown in three side views. Dividing the system into isolation blocks for the flat sides of cans 101, 102, and 103 is straightforward and consistent with the principles described previously. Note that the shape and size of the blocks can vary on different sides to precisely fit the geometry of the cans. The transition areas between the flat sides are defined by cylindrical surfaces 104. Cylindrical blocks can be applied at the junctions of these rounded sides. In the case shown, strips with a single element are used in these areas, while multiple elements can obviously be used when the rounded corner radius is larger. The corners where the three planar sides intersect require double-bent blocks 105. In this example, consistent with the single row of blocks at the junctions of the curved sides, there is only one double-bent block element at each of the eight corners. These block elements are triangular in shape, with each triangular corner having a 90-degree angle; this is practically feasible for a 1 / 8 section of a sphere. By implementing the triangular block elements and T-shaped corrugated joints, it is also feasible to construct larger spherical regions with numerous block elements. Therefore, the invention can also be applied to spherical shells and cylindrical shells with rounded end caps.

[0097] Further description of the design, principles, and implementation methods of the present invention

[0098] This invention relates to a novel solution for vacuum insulation of tanks containing fluids at sub-zero and cryogenic temperatures, enabling the application of vacuum insulation to ultra-large tanks of any size and shape for which no such insulation system was previously available. The provided solution can be used for tanks subjected to extremely low temperatures, such as containers for liquid hydrogen, where the total cumulative thermal shrinkage of the tank itself can be very large. The invention is also applicable to thermal insulation of pressure vessels with single-curved and double-curved surfaces. Double-layered vacuum insulation can also be used for tanks containing fluids at very high temperatures, accompanied by significant thermal expansion of the inner tank and stretching across the block joints.

[0099] The basic concept of this invention is that the vacuum insulation body of a cryogenic tank can be prefabricated into nearly identical block components that are securely and safely attached to the outer surface of the inner tank. The specific dimensions of these insulation blocks depend on the geometry of the tank, allowing the components to fit the dimensions and shapes of various portions of the tank surface. Typical base dimensions of the block components can range from 0.25 to 2.5 meters or larger, depending on the specific thermal range, material properties, and tank shape. For example, assuming a 6 mm shrinkage per meter of cryogenic tank, the gap between adjacent block components at the skin layer would shrink by 3 to 15 mm for the aforementioned block dimensions. This shrinkage at the sealing joints between the block components is feasible in this invention.

[0100] The thickness of the insulator inside each block can vary depending on the type of insulator material used. Polyurethane foam (PUF) is widely used as an insulator material for cryogenic industrial applications. This material can also be reinforced and hardened with glass fiber or other types of fiber reinforcement, and is called reinforced polyurethane foam (R-PUF). For example, this material is widely used for the insulators of large LNG transport tanks. The tensile strength of these materials is typically higher than their compressive strength, with the compressive strength being more valuable in current applications; and generally, the strength increases as the temperature decreases. Normal long-term compressive strength can be in the range of 1 to 2 MPa, which is significantly greater than the actual load after vacuuming (approximately 1 atm or 0.1 MPa). Good references on this type of insulator can be found at the following link:

[0101] http: / / www.ivt.ntnu.no / ept / fag / tep4215 / innhold / LNG%20Conferences / 2007 / fscommand / PO_11_Y_Lee_s.pdf

[0102] The type of insulating material used may vary depending on the block. For example, a block that is part of an integrated tank support system may be selected to have higher stiffness and strength than a block that only withstands atmospheric pressure.

[0103] Insulation materials primarily serve as supports to maintain the distance between the outer shell and the cryogenic vessel. An ideal vacuum does not transfer heat through conduction or convection; therefore, conductive heat intrusion is mainly caused by the insulation material. The insulation also significantly reduces heat transfer via radiation. Therefore, a thicker insulation layer reduces overall heat transfer (heat intrusion). Thermal stress will also develop within the insulation layer according to its thickness; thermal stress within the insulation material itself is minimal due to its low stiffness. Considering insulation performance and cost, the optimal insulation thickness should be determined based on the specific application.

[0104] This invention provides a tank with an isolation system that utilizes a vacuum applied to a closed, refrigerated container. A particularly interesting feature is an isolation layer constructed from preferably prefabricated modular isolation block elements attached to the tank, wherein the connection between the block elements and the blocks preferably has the following characteristics:

[0105] - The size and shape of the block are determined based on the overall geometry of the tank and the surface shape at the installation location of the block, such as flat, single-curved, or double-curved;

[0106] - Each block has an external airtight skin that forms an airtight barrier against the supporting insulation material underneath;

[0107] - The outer surface skin is smaller than the area covered by the protrusions on the container to provide an open gap between adjacent blocks, which remain separated during the heat shrinkage of the inner tank;

[0108] - Attach an airtight and retractable seal to the surface opening of the gap;

[0109] - The outer sealing layer is attached to the supporting insulation material by adhesive and / or mechanical means;

[0110] - A porous insulating material located below and connected to the outer skin layer. For the spacer material of the porous insulating material, all air can be extracted, and after the air is evacuated (vacuumed), the strength can fully maintain and support the external pressure on the outer skin layer.

[0111] - A device for positioning and securing insulating blocks to the surface of a container, the device may include guide rails, adhesive and mechanical fastening devices;

[0112] - A continuous membrane sealing system, attached between and to adjacent blocks, consists of airtight connector strips attached to the outer skin of the blocks. The material and corrugated shape of the connecting seal allow for changes in the relative distance between the top skins of adjacent blocks caused by the thermal contraction of the inner tank. Simultaneously, the sealing system also bears the load provided by the pressure difference between the outside air and near-vacuum. This complete system of attached isolation blocks and the seal between blocks provides a complete airtight seal and isolation system around the entire outer surface of the isolation tank, achieving an airtight, vacuum-like isolation that allows for very large temperature differences (e.g., up to 300°C or higher) between the container and the surrounding environment.

[0113] - An important part of the invention is the specific definition of the geometry of the corrugated skin that spans the open space between the blocks, thereby the shape and its deformability are based on the principle of minimum potential energy, and by this the skin allows the inner tank to shrink without generating high stress concentrations and "hot spots" in the corrugations, and in particular, avoids high stress at the points where the corrugations meet at the intersections.

[0114] As an alternative to the aforementioned prefabricated block concept, the blocks can be formed by spraying insulating material layer by layer onto the inner tank, and then shaping the blocks by carving, grinding, or sawing the gaps to create non-closed gaps between them. Anchoring devices can be attached to the tank surface before spraying to ensure good contact between the insulating material and the tank at all times. When applying the planar and corrugated portions of the outer skin, the outer surface can be smoothed to ensure good contact. In other respects, this method has the same performance as listed above.

[0115] In some preferred embodiments, the can and the method of manufacturing the can also include complete prefabrication of the vacuum can and rapid and efficient installation in a ship or vessel. Specific methods for lifting, transporting, installing, and supporting cans of the type described herein are also feasible, and these features are described in a separate invention. Notably, the described solution makes it feasible to avoid the use of wooden block supports and associated thermal bridges with the can, as the insulator is used for support, including at least one soft support structure. The advantages of this feasibility include the ability to complete and fully test the pressure of the can and check for leaks in the insulator on-site prior to transport and installation. Lifting, transporting, and installation can be carried out without disturbing or damaging the insulator system. Further details can be found in Patent Application No. 20200965 and the international patent application claiming priority thereto, both of which are incorporated herein by reference.

[0116] A general embodiment of the can of the present invention includes an inner tank and an outer airtight corrugated flexible shell, with block elements of an insulating body arranged together between the inner tank and the outer shell. When the can is in operation, a vacuum is maintained in the volume between the inner tank and the outer shell. The insulating elements include an airtight outer side and are arranged at intervals to ensure that open gaps between the block elements are maintained after cooling, and the stress in the corrugated outer membrane shell remains within acceptable limits. A general embodiment of the can may include any feature or step described or shown in any effective combination.

Claims

1. A tank suitable for storing and transporting fluids at cryogenic temperatures, the tank comprising: - an inner pressure tank, - a thermal insulation, - an outer shell, the outer shell being airtight, - wherein the thermal insulation is arranged outside the inner pressure tank and the outer shell is arranged outside the thermal insulation, - further comprising a coupling through the outer shell, wherein a vacuum pump outside the tank can be coupled to suck air and gas from the volume between the inner pressure tank and the outer shell, and - further comprising an opening from outside the tank to inside the inner pressure tank for loading and unloading fluids, - wherein the inner pressure tank contains fluids in operation and the volume between the inner pressure tank and the outer shell is in vacuum, - characterized in that - the thermal insulation comprises a plurality of block elements arranged side by side on the inner pressure tank with gaps between the block elements, - wherein the outer shell comprises a plurality of parts that have been joined together to cover the entire outer surface of the insulation, wherein the parts of the outer shell covering the insulated block elements have a shape matching the shape of the insulated block elements and the curved parts of the outer shell covering the gaps between the block elements have an inwardly or outwardly oriented curved shape when seen in cross section along the respective gap and are flexible due to the contraction or stretching of the curved shape.

2. The can according to claim 1, wherein, The gaps between the block elements comprise V-shaped or U-shaped gaps.

3. The can according to claim 1, wherein, The curved parts of the outer shell have a cosine shape, a cosine-like shape, or another smooth corrugation shape when seen in cross section along the gap.

4. The can according to any one of claims 1-3, wherein, The curved parts have superimposed cosine shapes or superimposed smooth corrugation shapes at locations where two curved parts cross.

5. The can according to claim 1 or 2, wherein, The initial curved shape across the gaps is generated by taking and scaling a shape resulting from a computer simulation of buckling of a thin sheet across the gaps between blocks, the computer simulation taking into account compression and also normal pressure.

6. The can according to claim 1 or 2, wherein, The initial curved shape at the crossings between gaps is generated by taking and scaling a shape resulting from a computer simulation of buckling of a thin sheet across the open area between adjacent blocks at the crossings, the computer simulation taking into account bilateral compression and also normal pressure.

7. The can according to claim 4, wherein, The initial curved shape at the crossings between gaps is generated by taking and scaling a shape resulting from a computer simulation of buckling of a thin sheet across the open area between adjacent blocks at the crossings, the computer simulation taking into account bilateral compression and also normal pressure.

8. The can according to any one of claims 1-3 and 7, wherein, The curved parts of the outer shell covering the gaps are not shape stable but contract when the inner pressure tank cools and contracts and stretch when the inner pressure tank warms and expands, whereas the parts of the outer shell on the block elements are shape stable and fastened to the block elements by adhesion and / or mechanical means and do not deform relative to the respective block elements.

9. The can according to claim 4, wherein, The curved portion of the outer shell covering the gap is not shape stable but shrinks when the inner pressure tank cools and shrinks and stretches when the inner pressure tank warms and expands, while the portion of the outer shell on the block elements is shape stable and fastened to the block elements by adhesive and / or mechanical means and does not deform relative to the respective block element.

10. The can according to claim 5, wherein, The curved portion of the outer shell covering the gap is not shape stable but shrinks when the inner pressure tank cools and shrinks and stretches when the inner pressure tank warms and expands, while the portion of the outer shell on the block elements is shape stable and fastened to the block elements by adhesive and / or mechanical means and does not deform relative to the respective block element.

11. The can according to claim 6, wherein, The curved portion of the outer shell covering the gap is not shape stable but shrinks when the inner pressure tank cools and shrinks and stretches when the inner pressure tank warms and expands, while the portion of the outer shell on the block elements is shape stable and fastened to the block elements by adhesive and / or mechanical means and does not deform relative to the respective block element.

12. The can according to any one of claims 1-3 and 7, wherein, The tank comprises outer shell portions with superimposed curved shapes, wherein two curved portions cross at the area center of the portion, wherein the superimposed curved shapes are free of joints and the joints between the outer shell portions are located at positions of minimum stress, whereby the curved shapes are arranged along the center line of the outer shell portions.

13. The can according to claim 4, wherein, The tank comprises outer shell portions with superimposed curved shapes, wherein two curved portions cross at the area center of the portion, wherein the superimposed curved shapes are free of joints and the joints between the outer shell portions are located at positions of minimum stress, whereby the curved shapes are arranged along the center line of the outer shell portions.

14. The can of claim 5, wherein, The tank comprises outer shell portions with superimposed curved shapes, wherein two curved portions cross at the area center of the portion, wherein the superimposed curved shapes are free of joints and the joints between the outer shell portions are located at positions of minimum stress, whereby the curved shapes are arranged along the center line of the outer shell portions.

15. The can of claim 6, wherein, The tank comprises outer shell portions with superimposed curved shapes, wherein two curved portions cross at the area center of the portion, wherein the superimposed curved shapes are free of joints and the joints between the outer shell portions are located at positions of minimum stress, whereby the curved shapes are arranged along the center line of the outer shell portions.

16. A method for manufacturing a tank according to any one of claims 1-15, characterized by the following steps: manufacturing or providing the inner pressure tank, manufacturing or providing insulating block elements, manufacturing or providing an opening for filling or emptying fluid, manufacturing or providing a coupling for a vacuum pump, manufacturing or providing outer shell portions, arranging and fastening the block elements side by side on the outer surface of the inner pressure tank, arranging the opening and the coupling for a vacuum pump, arranging and joining the outer shell portions together.

17. The method of claim 16, wherein, The insulation is formed by a spraying step, followed by a step of carving out the insulation blocks.

18. The method of claim 17, wherein, The outer shell part is manufactured by stamping and die drawing, deep drawing or bulging of a sheet element of austenitic stainless steel or aluminium or other material suitable for this purpose, the bent portion being at the centre line and the superposed portion being at the centre of the sheet element.

19. Use of a tank according to any one of claims 1-15 for storing and transporting cryogenic fluids or other cold or hot fluids having a temperature differing more than 30°C from ambient temperature.

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