Heat insulation structure for reducing heat leakage of horizontal low-temperature liquid storage tank

Abstract

The invention relates to the technical field of liquid storage and transportation, and discloses a heat insulation structure for reducing heat leakage of a horizontal low-temperature liquid storage tank, which comprises end covers respectively arranged at two ends of the liquid storage tank, an inner tank and baffles symmetrically arranged in the inner tank, the baffle is arranged near the end cover, and a gap is formed between the baffle and the inner wall of the end cover; the upper end of the baffle is connected with the top of the inner tank, and a space for liquid circulation exists between the lower end of the baffle and the bottom of the inner tank. According to the invention, the medium environment around the root of the glass fiber reinforced plastic support body can be dynamically changed, and a main medium for exchanging heat with the glass fiber reinforced plastic support body is converted into a gas phase with an extremely low heat conductivity coefficient from a low-temperature liquid with a high heat conductivity coefficient, so that the heat leakage through a'heat bridge 'is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of liquid storage and transportation technology, and to a heat insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks. Specifically, it is applied to an internal baffle device of the storage tank that blocks the heat transfer path of thermal bridges by changing the local flow field and phase distribution. Background Technology

[0002] Clean energy is an internationally recognized important development direction, and the storage of cryogenic liquefied gases (such as liquid hydrogen, liquid helium, and liquid oxygen) is one of the main methods for large-scale storage and transportation in the energy industry. Horizontal cryogenic storage tanks are key equipment for the storage and transportation of cryogenic liquids, and their core requirement is to maintain the medium inside the tank at an extremely low boiling point temperature. Due to the extremely high latent heat of vaporization of these cryogenic liquids, any infiltration of external heat will lead to liquid evaporation and loss. In existing technologies, horizontal storage tanks typically employ a vacuum multi-layered insulated outer tank combined with an internal fiberglass support structure. While the fiberglass support connecting the inner and outer tanks provides some cryogenic insulation performance, it still creates a significant "thermal bridge" effect, becoming the main path for heat leakage.

[0003] Currently, most solutions to this problem focus on optimizing the support material itself, such as using composite materials with lower thermal conductivity or adding an auxiliary insulation layer. While these methods have some effect, they have significant limitations. First, improving material performance faces technical bottlenecks and cost constraints. Second, adding an insulation layer increases structural complexity and may affect support strength. More fundamentally, existing technologies have not changed the properties of the heat transfer medium at the end of the thermal bridge path; the support structure remains in direct contact with the cryogenic liquid, whose thermal conductivity is much higher than that of its gaseous phase. This means that as long as the support remains below the cryogenic liquid surface, the heat introduced through the thermal bridge will continue to be absorbed by the cryogenic liquid and cause evaporation, making it difficult to significantly reduce heat leakage from the cryogenic storage tank.

[0004] Therefore, there is an urgent need in this field for an innovative structure that can change the heat exchange environment at the thermal bridge terminal and effectively block the heat leakage path, which is of great significance for the storage of various low-temperature media. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a thermal insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks. This structure can dynamically change the medium environment around the root of the fiberglass support, changing the main heat exchange medium from a cryogenic liquid with high thermal conductivity to a gas phase with extremely low thermal conductivity, thereby significantly reducing heat leakage through the "thermal bridge".

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A heat insulation structure for reducing heat leakage in a horizontal cryogenic liquid storage tank, the horizontal cryogenic liquid storage tank including end caps and an inner tank respectively disposed at both ends of the horizontal cryogenic liquid storage tank, the heat insulation structure including baffles symmetrically disposed inside the inner tank; the baffles are disposed near the end caps and form a gap with the inner wall of the end caps; the upper end of the baffle is connected to the top of the inner tank, and there is a gap between the lower end of the baffle and the bottom of the inner tank for liquid flow.

[0008] Preferably, the end cap is an ellipsoidal end cap; the baffle is vertically arranged; the upper end of the baffle is fixedly connected to the top of the inner tank by welding; the material of the baffle is stainless steel.

[0009] The vertical baffle and the inner wall of the adjacent lateral ellipsoidal end cap form a relatively very narrow gap channel from top to bottom.

[0010] Furthermore, the heat insulation structure of the present invention also includes an outer tank disposed around the inner tank and a fiberglass support body disposed between the outer tank and the inner tank, wherein one end of the fiberglass support body is connected to the inner tank and the other end extends out from the outer tank.

[0011] A fiberglass support is a structural component made of fiberglass material. In liquid storage tanks, it is used to connect and support the inner tank and the outer tank. One end is fixed to the inner tank and the other end is fixed to the outer tank. In the structure of a typical horizontal liquid storage tank, fiberglass supports are installed at both ends of the tank body. Their functions are twofold: first, to provide mechanical support and prevent the inner tank from shaking or collapsing inside the outer tank; and second, because of the low thermal conductivity of the material, to minimize the transfer of external heat.

[0012] Furthermore, the maximum distance between the gap and the center of the end cap radius of the inner tank The following relationship must be satisfied:

[0013] ;

[0014] in, This is an empirical coefficient; furthermore, Preferred .

[0015] The principle of this invention is that within the gap between the baffle and the end cap, the gas phase generated by the heating and evaporation of the low-temperature liquid cannot diffuse rapidly, leading to a local pressure increase, thereby pushing down the liquid level. If If the pressure is too large and the gap is too wide, the generated gas phase can easily diffuse, and the local pressure cannot effectively accumulate, or the accumulated pressure is too small to overcome the static pressure difference and push the liquid level down. Therefore, The above relationship must be satisfied for the gap to significantly impede gas flow and diffusion, producing a gas jam effect. The gas phase generated by evaporation is confined within the gap, enabling the rapid and effective establishment of sufficient local pressure. This pressure is the direct driving force for achieving the liquid level differential and altering the environment at the support root.

[0016] Furthermore, the distance between the lower end of the baffle and the bottom of the inner tank... Not less than 50mm.

[0017] Regarding the distance between the lower end of the baffle and the bottom of the inner tank Not less than 50mm, based on the following considerations:

[0018] First, sufficient flow cross-section must be provided between the lower end of the baffle and the bottom of the inner tank to prevent local blockage or airlock caused by trace impurities or gas generated by evaporation. Second, it must accommodate dimensional deviations caused by thermal deformation of the storage tank during manufacturing, installation, and cryogenic operation. Considering the above factors, an integer of 50mm, which is easy to process and inspect, is selected to ensure the reliability of ensuring smooth liquid flow and the evacuability of the storage tank when the value is not less than this.

[0019] Furthermore, the working method of the baffle includes the following process: In the initial state, the cryogenic liquid surface submerges the connection root between the FRP support and the inner tank; when heat leakage occurs, the cryogenic liquid in the gap evaporates to generate a gas phase, resulting in an increase in local pressure within the gap; the increased pressure pushes down the liquid surface in the gap, exposing the connection root between the FRP support and the inner tank to the gas phase environment. The advantage of being exposed to the gas phase environment is that it changes the medium environment around the root of the FRP support, changing the main heat exchange medium from the cryogenic liquid with high thermal conductivity to the gas phase with extremely low thermal conductivity, thereby significantly reducing the heat leakage through the "thermal bridge".

[0020] Furthermore, the calculation of the increase in pressure within the gap is based on the ideal body state equation:

[0021] ;

[0022] in, For gas phase pressure, The volume of the gas phase space within the gap. For hydrogen mass, The gas constant is The temperature is the gas temperature.

[0023] Furthermore, the distance between the gap and the center of the end cap The dimensional design method is as follows:

[0024] The rate of increase in gas phase pressure due to liquid evaporation within the gap for:

[0025] (1);

[0026] For the main body of the storage tank, the gas is supplied by total heat leakage. Generated and distributed in the total volume In the middle, the pressure increase rate of the main space of the storage tank. for:

[0027] (2);

[0028] To achieve the desired functionality, the following must be met: Substituting and simplifying formulas (1) and (2), we get:

[0029] (3);

[0030] Obtain the interstitial volume Design ceiling:

[0031] (4);

[0032] (5);

[0033] To simplify and conservatively design, ,Right now Substitute this equation into equation (4):

[0034] ;

[0035] Total volume of the inner tank of a horizontal storage tank Substitute into the above formula:

[0036] ;

[0037] After simplification, the distance between the gap and the center of the end cap is obtained. The final design expression:

[0038] (6);

[0039] in, The molar mass of the gas; Latent heat of vaporization; The radius of the cylindrical section of the inner tank, in meters (m). The length of the cylindrical section of the inner tank, in meters (m). This refers to the total volume of the inner tank, in m³. ; The heat leakage power through a single fiberglass support, in W; The total heat leakage power of the storage tank, in W, includes And heat leakage from the outer shell; The width of the gap formed between the baffle and the inner wall of the end cap, in meters; The distance between the lower edge of the baffle and the inner wall of the bottom of the inner tank, in meters; The gas temperature; For gap volume; It is the number of moles of low-temperature gas generated by liquid evaporation in the gap between the baffle and the inner wall of the end cap per unit time. The pressure of the gas phase space inside the gap; This refers to the gas phase pressure within the main space of the storage tank.

[0040] Furthermore, the distance between the lower end of the baffle and the bottom of the inner tank... Size design methods include:

[0041] spacing minimum value :

[0042] ;

[0043] spacing maximum value :

[0044] ;

[0045] in, This is an empirical coefficient, ranging from 0.2 to 0.5; This is the distance between the gap and the center of the end cap;

[0046] Then by ,get:

[0047] .

[0048] Furthermore, the rate of increase in gas phase pressure within the gap due to liquid evaporation Pressure growth rate of the main tank space The ratio of their volumes is proportional to the reciprocal of the ratio of their volumes, which satisfies the following equation:

[0049] ;

[0050] in, For gap volume; This refers to the total volume of the inner tank; The pressure of the gas phase space inside the gap; This refers to the gas phase pressure within the main space of the storage tank.

[0051] Compared with the prior art, the present invention provides a heat insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks, which has the following beneficial effects:

[0052] (1) By changing the heat exchange medium of the thermal bridge terminal from liquid to gas, the present invention utilizes the extremely low thermal conductivity of gas to suppress heat conduction, effectively reducing heat leakage caused by the support structure and reducing the evaporation loss of the low temperature medium.

[0053] (2) The structure of the present invention does not require changes to the main structure and supporting materials of the existing storage tank. The effect can be achieved simply by adding internal components. The structure is simple, easy to implement, highly reliable, and will not affect the structural strength of the support.

[0054] (3) The mechanism of the present invention is a passive adaptive process. The occurrence of heat leakage itself will drive local pressure changes and thus change the liquid level. It can automatically maintain its heat leakage reduction effect without external intervention.

[0055] (4) This invention avoids the use of expensive composite insulation materials or complex auxiliary cooling systems, has low manufacturing costs, and has extremely high economic value and promotion value.

[0056] (5) The present invention has a simple structure, requires no additional energy consumption, and has high reliability. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the structure of the horizontal cryogenic liquid storage tank in Embodiment 1 of the present invention;

[0058] Figure 2 for Figure 1 Enlarged view of a narrow gap in the middle;

[0059] Figure 3 This is a schematic diagram of the initial liquid filling state (high liquid level) of the present invention;

[0060] Figure 4 This is a schematic diagram of the working state of the present invention (low liquid level, gas phase accumulation).

[0061] The meanings of the reference numerals in the figure are as follows:

[0062] 1. Outer tank; 2. Inner tank; 3. Fiberglass support; 4. End cap; 5. Baffle; 6. Top of inner tank; 7. Bottom of inner tank; 8. Liquid phase; 9. Cryogenic liquid surface; 10. Connection root; 11. Gap; 12. Gaseous phase. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0065] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0066] Example 1

[0067] like Figures 1 to 4 As shown, this embodiment provides a heat insulation structure for reducing heat leakage in a horizontal cryogenic liquid storage tank. The horizontal cryogenic liquid storage tank includes end caps 4, an inner tank 2, and an outer tank 1 disposed around the inner tank. The heat insulation structure includes baffles 5 symmetrically disposed inside the inner tank 2. The baffles 5 are disposed near the end caps 4 and form a gap 11 between them and the inner wall of the end caps 4. The upper end of the baffles 5 is connected to the top of the inner tank 2, and there is a gap between the lower end of the baffles 5 and the bottom of the inner tank 2 for liquid flow.

[0068] In one specific implementation of this embodiment, the heat insulation structure further includes a fiberglass support 3 disposed between the outer tank 1 and the inner tank 2. One end of the fiberglass support 3 is connected to the inner tank 2, and the other end extends out of the outer tank 1.

[0069] In one specific implementation of this embodiment, the maximum distance between the gap 11 and the center of the end cap 4 is... The radius of the inner tank 2 cylindrical section The following relationship must be satisfied:

[0070] ;

[0071] in, For coefficients. Preferred. .

[0072] In one specific implementation of this embodiment, the distance H between the lower end of the baffle 5 and the bottom of the inner tank 2 is not less than 50mm.

[0073] In one specific implementation of this embodiment, the working method of the baffle 5 includes the following process: In the initial state, the low-temperature liquid surface 9 submerges the connection root 10 between the fiberglass support 3 and the inner tank 2; when heat leakage occurs, the low-temperature liquid in the gap 11 evaporates to generate a gas phase, resulting in an increase in local pressure in the gap 11; the increased pressure presses down the low-temperature liquid surface 9 in the gap 11, exposing the connection root 10 between the fiberglass support 3 and the inner tank 2 to the gas phase environment.

[0074] Example 2

[0075] This implementation further describes the thermal insulation structure in Example 1 with specific dimensions, as follows:

[0076] In this embodiment, the horizontal cryogenic liquid storage tank is a horizontal liquid hydrogen storage tank. The inner tank 2 of the horizontal liquid hydrogen storage tank has a diameter of 3.2m, a length of 12m, an initial filling rate of 90%, and a working pressure of 0.8MPa.

[0077] In this embodiment, the structural design and installation of the baffle 5 are as follows: Inside the inner tank 2 of the horizontal liquid hydrogen storage tank, two 10mm thick 304 stainless steel baffles 5 are symmetrically and vertically installed 150mm from the inner wall of the ellipsoidal end cap 4 on the side. The upper end of the baffle 5 is fixedly connected to the top 6 of the inner tank by welding, and the lower end maintains a distance H of 400mm from the bottom 7 of the inner tank. This distance ensures the normal flow of liquid hydrogen in the tank. The height of the baffle 5 is 2.8m, forming a narrow annular gap 11 with the inner wall of the end cap 4, and the width G of the gap 11 is 150mm.

[0078] In this embodiment, the heat transfer process is calculated as follows:

[0079] The heat transfer process of the fiberglass support 3 is calculated using Fourier's law of thermal conductivity:

[0080] ;

[0081] in, The thermal conductivity of the fiberglass support 3 is taken as 0.25 W / (m·K); Let be the cross-sectional area of ​​the fiberglass support 3, taken as 0.05m². 2 ; The temperature difference between the inner and outer tanks is taken as 253K; The length of the fiberglass support 3 is taken as 0.8 m. The calculated heat leakage power of a single fiberglass support 3 is... It is approximately 3.95W.

[0082] In this embodiment, the gas phase space pressure is calculated as follows:

[0083] When the liquid hydrogen in gap 11 evaporates due to heat, the local pressure change (i.e., the pressure change within the gap) is calculated using the ideal gas law:

[0084] ;

[0085] in, The pressure is the gas phase pressure (Pa). The volume of the gas phase space within the narrow gap 11 (m³). This represents the amount of hydrogen gas (mol). The ideal gas constant is 8.314 J / (mol·K) The gas temperature is 20 K. In the initial state, within gap 11... , When heat leakage causes the generation of 0.1 mol of hydrogen gas, the pressure inside the gap can rise to approximately 0.86 MPa.

[0086] This embodiment uses a thermodynamic three-zone model to analyze the phase change heat and mass transfer process within the gap formed by baffle 5, as detailed below:

[0087] Liquid phase region: The main liquid hydrogen region below the lower end of baffle 5, with the temperature maintained at 20 K.

[0088] The gas-liquid interface region: the evaporation interface within gap 11, the evaporation rate is calculated using the following formula:

[0089] ;

[0090] in, The evaporation rate is expressed as mass evaporation rate (kg / s). is the mass transfer coefficient (m / s). The interface area (m²) This represents the actual steam density (kg / m³). The density is the saturated steam density (kg / m³).

[0091] Gas phase region: The region where hydrogen gas accumulates in the upper part of the gap, with a temperature of approximately 22 K.

[0092] The working process of the thermal insulation structure in this embodiment is as follows:

[0093] Initially, the liquid hydrogen level is 2.5m, submerging the connection root 10 between the fiberglass support 3 and the inner tank 2. When ambient heat is transferred through the fiberglass support 3, the liquid hydrogen within the narrow gap 11 is heated first. Due to the limited space, the generated hydrogen cannot diffuse quickly, leading to a local (within the gap) pressure increase. According to the ideal gas law, when the temperature rises from 20K to 22K, the pressure increases by 0.2MPa accordingly.

[0094] The increased pressure forces the gas-liquid interface downwards, causing the liquid level to drop below the connection root 10 of the FRP support, approximately 100 mm. At this point, the connection root 10 of the FRP support 3 is completely exposed to the hydrogen environment. Because the thermal conductivity of hydrogen (0.017 W / (m·K)) is much lower than that of liquid hydrogen (0.12 W / (m·K)) under increased local pressure, the actual heat loss through the FRP support 3 is reduced as follows:

[0095] ;

[0096] in, The thermal conductivity of hydrogen under increased local pressure is taken as 0.017 W / (m·K); the actual heat loss of a single FRP support 3 is calculated. It is approximately 0.27W.

[0097] The total thermal resistance of the fiberglass support 3 is composed of the fiberglass and the surrounding medium connected in series. However, the thermal resistance of the surrounding medium is much greater than that of the fiberglass, so the total thermal resistance can be approximated as depending on the medium environment.

[0098] Assuming the dimensions of fiberglass support 3 , and temperature difference If the medium remains constant before and after the change, then the change in heat loss depends only on the thermal conductivity of the medium. The changes.

[0099] ;

[0100] in, Let be the thermal conductivity of liquid hydrogen, taken as 0.12 W / (m·K).

[0101] In summary, the liquid storage tank using the insulation structure in this embodiment has reduced heat leakage by 85.8% compared to the original.

[0102] Example 3

[0103] This implementation further discloses the design of key geometric parameters for the gap, as follows:

[0104] The core of the insulation structure of this invention is that at both ends of the inner tank 2, adjacent to the end cap 4, there is a flat baffle 5 perpendicular to the horizontal axis of the tank, forming a gap 11 (control body) between the baffle surface and the inner wall of the end cap 4. By scientifically designing the geometry of this gap, the rate of increase in gas phase pressure due to liquid evaporation within the gap 11 is controlled when heat leakage occurs. The pressure growth rate was significantly higher than that of the main tank space. The resulting pressure difference pushes down the liquid level within gap 11, exposing the connecting root 10 of the fiberglass support 3 from the high thermal conductivity cryogenic liquid environment to the extremely low thermal conductivity gas phase environment, thereby significantly reducing heat loss through the "thermal bridge". Therefore, the effectiveness of the insulation structure of this invention depends on whether a pressure higher than that of the main tank space can be quickly established within the gap 11 formed between the baffle 5 and the inner wall of the end cap 4. For this purpose, the key geometric parameters of this gap 11 need to be designed. A design method based on thermodynamic principles is provided below.

[0105] 1) Distance between gap 11 and the center of end cap 4 The design method is as follows:

[0106] Ensure that when heat leakage occurs, the pressure increase rate within gap 11 is much higher than the pressure increase rate in the main space of the storage tank.

[0107] Pressure growth rate analysis: According to the ideal gas law, the pressure growth rate within a fixed volume is expressed as:

[0108] ;

[0109] in, denoted as the molar formation rate of the gas.

[0110] For gap 11, the gas mainly loses heat due to the heat leakage from the fiberglass support 3. This leads to evaporation, therefore The rate of increase in gas phase pressure within gap 11 due to liquid evaporation is then determined. for:

[0111] (1);

[0112] in, The molar mass of the gas; Latent heat of vaporization; Radius of the cylindrical section of inner tank 2, in meters (m). The length of the cylindrical section of inner tank 2 is given in meters. The total volume of inner tank 2, in m³, can be approximated as: ; The heat leakage power through a single fiberglass support 3, in W; The total heat leakage power of the storage tank, in W, includes And heat leakage from the outer shell of the outer tank 1; The width of the gap 11 formed between the baffle 5 and the inner wall of the end cap 4, in meters (m). The distance between the lower edge of baffle 5 and the bottom inner wall of inner tank 2, in meters; The gas temperature; For gap volume; The moles of low-temperature gas generated by liquid evaporation within the gap 11 between the baffle 5 and the inner wall of the end cap 4 per unit time. The pressure of the gas phase space inside gap 11.

[0113] For the main body of the storage tank, the gas is supplied by total heat leakage. Generated and distributed in the total volume In the middle, the pressure increase rate of the main space of the storage tank. for:

[0114] (2);

[0115] in,

[0116] To achieve the desired functionality, the following must be met: Substituting and simplifying formulas (1) and (2), we get:

[0117] (3);

[0118] After recombination, the interstitial volume is obtained. Design ceiling:

[0119] (4);

[0120] Geometric model conversion:

[0121] Interstitial volume It is a function of its geometric dimensions. In this invention, gap 11 is an irregular curved surface located between the flat baffle 5 and the arc-shaped end cap 4. Its volume can be approximated with high precision as the gap width. With end cap 4 inner surface area The product of . For a standard ellipsoidal end cap, its inner surface area The radius of the cylindrical section of inner tank 2 Related, can be estimated as ( For the common 2:1 ellipsoidal end cap, the coefficient related to the shape of the end cap is 4. Therefore:

[0122] (5);

[0123] To simplify and conservatively design, it is advisable to... ,Right now Substituting this equation into equation (4):

[0124] ;

[0125] Typically, the total volume of the inner tank 2 of a horizontal storage tank is... Substitute into the above formula:

[0126] ;

[0127] After simplification, the final design expression for the gap width G is obtained:

[0128] (6);

[0129] Formula (6) shows that the gap width It must be less than the length of the storage tank. The heat leakage ratio of the fiberglass support body 3 ( The product of () is the decisive condition for ensuring that overpressure can be quickly established within gap 11. In practical design, a smaller value should be selected as much as possible while meeting manufacturing process requirements. value.

[0130] 2) Bottom spacing The design method is as follows:

[0131] spacing The design must simultaneously meet both functional and reliability constraints, and its value must be selected within a reasonable range, including the following selection process: using minimum value constraints. and maximum value constraint

[0132] Step S21, Minimum value constraint .

[0133] spacing minimum value The aim is to ensure the basic reliability of storage tank operations:

[0134] Liquid flowability: Provides sufficient cross-section to prevent the formation of flow dead zones at the bottom of baffle 5, ensuring that liquid can freely flow into and out of the gap area during filling, discharging and operation.

[0135] Tolerance: It must accommodate dimensional deviations and thermal deformations that occur during the manufacturing, welding, and cryogenic conditions of the storage tank, and prevent the baffle 5 from contacting the bottom 7 of the inner tank.

[0136] Emptying capability and anti-clogging: Ensure that the storage tank can be completely emptied by gravity, while allowing trace amounts of impurities to pass through.

[0137] Taking all the above factors into account, select the desired spacing. The minimum value is It is a reliable empirical value that takes into account flowability, tolerance, evacuability and safety.

[0138] Step S22, Maximum value constraint .

[0139] spacing maximum value The core mechanism of this invention is the key to its effectiveness.

[0140] Constraint Principle: An excessively large value means the opening at the lower end of the baffle is too large, making the gap 11 area too open to the main tank space. When heat leakage occurs and gas phase is generated within the gap, the pressure cannot be effectively confined within the gap but will quickly leak into the main space through the large opening. This will prevent the local pressure within gap 11 from rising quickly enough to suppress the liquid level, thus rendering the "liquid level suppression - change of heat transfer medium" mechanism ineffective.

[0141] As a conservative engineering judgment, it may be required that... The value should be designed to be small enough; this qualitative objective can be achieved in the following ways:

[0142] first, The value should be significantly smaller than the characteristic size of the system, i.e., satisfy the following condition. .

[0143] Secondly, to achieve effective local pressure buildup, the flow resistance at the bottom opening of baffle 5 must be significantly greater than the flow resistance inside gap 11. This can be achieved by comparing the hydraulic diameters of the two. (Hydraulic diameter of the gap region) The hydraulic diameter of the opening at the bottom of baffle 5 To ensure that the resistance at the opening dominates, the following condition must be met:

[0144] ;

[0145] Simplified, we get:

[0146] ;

[0147] in, It is an empirical coefficient much smaller than 1, ranging from 0.2 to 0.5. This formula indicates the spacing of the openings at the bottom of the baffle 5. It should be significantly smaller than the width of gap 11. .

[0148] Step S23: Determination of the final design value.

[0149] Baffle 5 bottom spacing The final design value must lie within the range defined by the minimum and maximum values:

[0150] ;

[0151] Under the premise of meeting the constraints of this range, from the perspective of optimizing thermal insulation performance, priority should be given to selecting areas closer to the zone. The value of is smaller because This value helps to effectively establish local overpressure and enhances the effect of the present invention.

[0152] 3) The influence of the total tank volume on the dynamic response characteristics of the insulation effect.

[0153] The thermal insulation effect of this invention is a dynamic process. Its response speed—the time required from the onset of heat leakage to the establishment of an effective pressure difference and the drop in the cryogenic liquid level 9 below the connection root 10 of the fiberglass support 3—is significantly influenced by the system's geometry. Specifically, the total volume of the inner tank 2... It is a key system parameter.

[0154] This effect stems from the core working mechanism of this invention. From formulas (1) and (2), it can be derived that the rate of increase in gas phase pressure within gap 11 due to liquid evaporation is... Pressure growth rate of the main tank space The ratio of their volumes is proportional to the reciprocal of the ratio of their volumes, which satisfies... Among them, the interstitial volume It is a fixed value determined by the structure of baffle 5.

[0155] For large storage tanks ( ): Pressure increase rate of the main space of the storage tank It is very slow. Even if only a small amount of gas is generated within gap 11, a significant pressure difference relative to the main space can be quickly established. Therefore, large storage tanks are beneficial for the rapid activation of the effects of this invention and have good dynamic response characteristics.

[0156] For small and medium-sized storage tanks ( ): Rate of increase in pressure within the main body of the storage tank Relatively quickly. More gas needs to be generated within gap 11 to establish an effective pressure differential, which prolongs the system response time. Therefore, small and medium-sized storage tanks will delay the manifestation of the effects of this invention.

[0157] Total volume of inner tank 2 This does not affect the correctness of the principle of the invention, but it significantly modulates its dynamic response characteristics. The larger the tank size, the higher the design tolerance; the smaller the size, the more precisely the parameters need to be optimized, especially to reduce... and To ensure effectiveness. This understanding provides a clear and practical theoretical basis and engineering guidance for determining the parameters of this invention in different application scenarios.

[0158] The structure of this invention features a vertical baffle 5 located near the inner wall of the end cap inside the storage tank, forming a narrow gap with the inner wall. Utilizing the characteristic that the local pressure increases within the gap 11 due to the evaporation of the cryogenic liquid upon heating, the medium surrounding the connection root 10 of the fiberglass support 3 is replaced from a liquid phase 8 with high thermal conductivity to a gaseous phase 12 with low thermal conductivity. The extremely low thermal conductivity of the gaseous phase significantly reduces heat leakage through the glass support 3, thereby effectively reducing evaporation losses of various cryogenic media such as liquid hydrogen, liquid helium, and liquid oxygen.

[0159] The working principle of this invention is as follows: During the initial filling of the cryogenic liquid (e.g., 90% filling), the liquid level is at a high position, submerging the connection root 10 between the fiberglass support 3 and the inner tank 2. When the liquid storage tank is stationary and exchanges heat with the external environment, heat is introduced through the "thermal bridge" of the fiberglass support 3. In the structure of this invention, due to the extremely narrow gap 11 between the baffle 5 and the inner wall of the end cap 4, the gaseous phase 12 generated after absorbing heat leakage in this area cannot diffuse rapidly, resulting in a significant increase in the gas phase pressure in this local area. The increased pressure pushes the liquid level in the narrow gap 11 downward, causing the liquid level in the local area to drop below the connection root 20 between the fiberglass support 3 and the inner tank 2. At this time, the medium exchanging heat with the connection root 10 of the fiberglass support 3 changes from the original cryogenic liquid to the accumulated gas phase. Since the thermal conductivity of the gaseous phase 12 is much lower than that of its liquid phase 8, the heat introduced through the thermal bridge cannot be efficiently absorbed, thereby achieving a significant reduction in heat leakage.

[0160] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A thermal insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks, characterized in that: The horizontal cryogenic liquid storage tank includes end caps and an inner tank respectively disposed at both ends of the horizontal cryogenic liquid storage tank. The heat insulation structure includes baffles symmetrically disposed inside the inner tank. The baffles are disposed near the end caps and form a gap with the inner wall of the end caps. The upper end of the baffles is connected to the top of the inner tank, and there is a gap between the lower end of the baffles and the bottom of the inner tank for liquid flow.

2. The insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks according to claim 1, characterized in that: It also includes an outer tank located around the inner tank and a fiberglass support body located between the outer tank and the inner tank. One end of the fiberglass support body is connected to the inner tank, and the other end extends out from the outer tank.

3. The insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks according to claim 1, characterized in that, The distance between the gap and the center of the end cap Radius of the inner cylindrical section The following relationship must be satisfied: ； in, This is an empirical coefficient.

4. The insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks according to claim 1, characterized in that, The distance between the lower end of the baffle and the bottom of the inner tank Not less than 50mm.

5. The insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks according to claim 1, characterized in that, The working method of the baffle The process includes the following steps: In the initial state, the cryogenic liquid surface submerges the connection root between the fiberglass support and the inner tank; when heat leakage occurs, the cryogenic liquid in the gap evaporates to generate a gas phase, resulting in an increase in local pressure within the gap; the increased pressure pushes down the liquid surface in the gap, exposing the connection root between the fiberglass support and the inner tank to the gas phase environment.

6. The insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks according to claim 1, characterized in that, The calculation of the increase in pressure within the gap is based on the ideal body state equation: ； in, For gas phase pressure, The volume of the gas phase space within the gap. For hydrogen mass, The gas constant is... The temperature is the gas temperature.

7. The insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks according to claim 1, characterized in that, The distance between the gap and the center of the end cap The dimensional design method is as follows: The rate of increase in gas phase pressure due to liquid evaporation within the gap for: （1）； For the main body of the storage tank, the gas is supplied by total heat leakage. Generated and distributed in the total volume In the middle, the pressure increase rate of the main space of the storage tank. for: （2）； To achieve the desired functionality, the following must be met: Substituting and simplifying formulas (1) and (2), we get: （3）； Obtain the interstitial volume Design ceiling: （4）； （5）； To simplify and conservatively design, ,Right now Substitute this equation into equation (4): ； Total volume of the inner tank of a horizontal storage tank Substitute into the above formula: ； After simplification, the distance between the gap and the center of the end cap is obtained. The final design expression: （6）； in, The molar mass of the gas; Latent heat of vaporization; The radius of the cylindrical section of the inner tank, in meters (m). The length of the cylindrical section of the inner tank, in meters (m). This refers to the total volume of the inner tank, in m³. ; The heat leakage power through a single fiberglass support, in W; The total heat leakage power of the storage tank, in W, includes And heat leakage from the outer shell; The width of the gap formed between the baffle and the inner wall of the end cap, in meters; The distance between the lower edge of the baffle and the inner wall of the bottom of the inner tank, in meters; The gas temperature; For gap volume; It is the number of moles of low-temperature gas generated by liquid evaporation in the gap between the baffle and the inner wall of the end cap per unit time. The pressure of the gas phase space inside the gap; This refers to the gas phase pressure within the main space of the storage tank.

8. The insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks according to claim 1, characterized in that, The distance between the lower end of the baffle and the bottom of the inner tank Size design methods include: spacing minimum value : ； spacing maximum value : ； in, This is an empirical coefficient, ranging from 0.2 to 0.5; This is the distance between the gap and the center of the end cap; Then by ,get: 。 9. The insulation structure for reducing heat leakage in horizontal cryogenic liquid storage tanks according to claim 1, characterized in that, The rate of increase in gas phase pressure due to liquid evaporation within the gap Pressure growth rate of the main tank space The ratio of their volumes is proportional to the reciprocal of the ratio of their volumes, which satisfies the following equation: ； in, For gap volume; This refers to the total volume of the inner tank; The pressure of the gas phase space inside the gap; This refers to the gas phase pressure within the main space of the storage tank.

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