A heat-insulating low-temperature container

Abstract

The invention discloses an insulated low-temperature container, and relates to the technical field of low-temperature container insulation. A nanoporous insulation material layer and a cured resin layer are sequentially arranged on the outer wall of the inner liner of the low-temperature container. The invention wraps the nanoporous insulation material around the outer wall of the gas cylinder, and uses a cured resin to fix the strength of the outermost side of the nanoporous material, so as to meet the strength requirements of the use, transportation, and hoisting of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation of cryogenic containers, and in particular to a thermally insulated cryogenic container. Background Art

[0002] At present, traditional high vacuum multi-layer insulation is the widely used insulation method for ultra-low temperature containers. It uses aluminum foil and glass fiber composite to form an insulation material. The insulation material is covered on the outer surface of the container liner. Then a vacuum pump is used to evacuate the space between the inner liner and the outer liner to a high vacuum to achieve the purpose of insulation.

[0003] Traditional high-vacuum multi-layer insulated containers require a high degree of vacuum, and the vacuuming time is as high as more than 7 days. In addition, the product needs to be heated to achieve the ideal vacuum requirement. The cleanliness requirements of the interlayer (the outer surface of the inner liner and the inner surface of the outer liner) are very high, and must be cleaned, dried, and degreased. The welds related to the interlayer have high requirements, and each welding position must be checked for leaks. The inspection requirements are high and the inspection is difficult.

[0004] It is difficult to maintain the vacuum in traditional high-vacuum multi-layer insulated containers for a long time. Although adsorbents (molecular sieves and palladium oxide) and other adsorbent materials are arranged in the vacuum layer, their vacuum design life is generally 3-5 years, which cannot achieve long-term insulation. In addition, palladium oxide is a precious metal with a high market price, which causes the price of vacuum insulated containers to remain high.

[0005] This patent refers to the "Flexible Aerogel Insulation Material Specification" issued by NASA and the American Society for Testing and Materials (ASTMC1728-17 "Nanoporous Aerogel Composite Insulation Products", GB / T34336-2017 "Nanoporous Aerogel Composite Insulation Products" and relevant literature and materials from the National University of Defense Technology, Harbin Institute of Technology, Zhejiang University, and the Chinese Academy of Sciences. Further research and development of new insulation materials and insulation methods to replace the traditional high vacuum multi-layer insulation method. Its insulation performance is comparable to that of existing high vacuum multi-layer insulation. The insulation effect can be permanently maintained through new materials and processes, which greatly reduces the production, material and maintenance costs of cryogenic containers. Summary of the invention

[0006] In order to reduce the weight of the cryogenic container and overcome the above-mentioned problems, the present invention adopts the following technical solution: an insulated cryogenic container, comprising an inner liner, the inner liner comprising a cylinder, a front head, and a rear head, and a nanoporous insulation material layer, a cured resin layer, and a carbon fiber layer are sequentially arranged on the outer wall of the inner liner; the front head and the rear head are both provided with a supporting and fixing mechanism for fixing the nanoporous insulation material layer.

[0007] Preferably, the front head is connected to an extension pipe, and the extension pipe is provided with a valve.

[0008] Preferably, a seventh supporting fixing ring is provided on the cylinder.

[0009] Preferably, an eighth supporting fixing ring is provided on the cylinder.

[0010] Preferably, the rear head is provided with a first supporting and fixing ring, a second supporting and fixing ring and a third supporting and fixing ring in sequence from the outside to the center.

[0011] Preferably, the front head is provided with a fourth supporting and fixing ring, a fifth supporting and fixing ring and a sixth supporting and fixing ring in sequence from the outside to the center.

[0012] Preferably, the nanoporous thermal insulation material layer comprises: methyl orthosilicate and reinforcing fibers.

[0013] Furthermore, the components of the reinforcing fiber include silicon dioxide and aluminum oxide.

[0014] Furthermore, the reinforcing fiber also includes at least one of ferric oxide, barium oxide, titanium dioxide and calcium oxide.

[0015] Preferably, the nanoporous thermal insulation material layer component also includes hexamethyldisiloxane.

[0016] Preferably, the mass ratio of silicon dioxide, aluminum oxide and iron oxide is 53-58:40-42:0.7-1.

[0017] Preferably, the mass ratio of methyl orthosilicate to reinforcing fiber is 60-80:8-16.

[0018] A method for preparing a nanoporous thermal insulation material comprises the following steps: mixing silicon dioxide, aluminum oxide and iron oxide and heating them to a molten state, blowing the molten material into a fibrous material by a high-speed airflow, and cooling; mixing methyl orthosilicate, deionized water and hydrochloric acid and stirring them to form a sol by hydrolysis and polycondensation reaction, adding the fibrous material and ammonia water, allowing the sol to form a sol by a condensation reaction, and then adding anhydrous ethanol to form a gel after the gel loses its fluidity; and slowly releasing the ethanol and cooling it to room temperature to obtain the nanoporous thermal insulation material.

[0019] The present invention adopts a new type of insulation material to replace the traditional high vacuum multi-layer insulation method, innovates a new insulation method for low-temperature containers, permanently bids farewell to the problem of "weakness" of vacuum in high vacuum multi-layer insulation, and completely cancels the original high vacuum multi-layer insulation vacuum pumping, welding, outer tank leak detection and other production processes, making the production process more simplified and easy to operate.

[0020] By changing the insulation type and using nanoporous insulation materials, the advantages are as follows:

[0021] 1. Its ultra-low thermal conductivity coefficient. Since the mass fraction of aerogel solid itself is very small and it is a porous body with pore diameters in the nanometer scale, the solid phase can be regarded as composed of numerous thin pore walls of micropores. The heat transfer in the solid has to go through a nearly infinitely long distance. The solid thermal conductivity in the aerogel is greatly weakened by this huge long-path effect and becomes very small.

[0022] 2. Low thermal radiation: Due to its nanoporous structure, nearly infinite solid / gas interfaces are formed inside the material. When the thermal radiation rays pass through each layer of the interface, they will be reflected, absorbed, transmitted and re-radiated. This is equivalent to setting up nearly infinite heat shields on the propagation path of the thermal radiation. The nearly infinite reflection effect causes the thermal radiation propagation ability to decay rapidly, and most of it is finally absorbed in the surface layer of the insulation material close to the hot surface. The radiation heat conduction becomes very low at room temperature.

[0023] 3. Ultra-low convective heat transfer. For gas to carry out convective heat transfer, there must be a large enough space. The pore size of aerogel is generally less than 50nm. In such nanopores, all air molecules lose their macroscopic migration ability and do not have the conditions for convective heat transfer. Therefore, the convective heat transfer of aerogel is also well limited.

[0024] 4. Super strong operating temperature range -196℃~950℃.

[0025] 5. It has strong flame retardancy. The material itself cannot burn. It has unique resistance to flame penetration and can withstand direct burning of flame for a long time.

[0026] 6. Good waterproof performance, its water repellency can reach more than 99%.

[0027] The present invention winds nanoporous insulation material around the outer wall of the gas cylinder for the outer liner of the low-temperature insulation container, and uses a curing resin to fix the outermost side of the nanoporous material to achieve strength requirements for use, transportation, hoisting, etc. of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the present invention;

[0029] Figure 2 This is a schematic diagram of the rear head structure. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] like Figure 1 As shown, an insulated low-temperature container, the inner liner 1 is composed of a cylinder part and a front head 21 and a rear head 22 at both ends, and the front head 21 and the rear head 22 are both curved surfaces. Figure 2As shown, the rear end cap 22 is welded with the first annular support and fixing ring 7, the second support and fixing ring 8 and the third support and fixing ring 9 in sequence from the outside to the center; with the same structure, the front end cap 21 is welded with the fourth annular support and fixing ring 7a, the fifth support and fixing ring 8a and the sixth support and fixing ring 9a in sequence from the outside to the center. In the cylinder part close to the rear end cap 22, the seventh support and fixing ring 10 is welded, and in the cylinder part close to the front end cap 21, the eighth support and fixing ring 10a is welded. An extension pipe 5 is welded at the center of the front end cap 21, and a valve 6 is installed on the extension pipe 5. The traditional front end cap is directly provided with a bottleneck, and a valve is installed on the bottleneck, but the curved surface at the bottleneck is relatively complex, and it is not easy to achieve complete wrapping of it. Therefore, under the premise of meeting the strength, the present invention increases the thermal resistance by increasing the extension pipe to reduce the heat transfer area, so that the heat leakage through the extension pipe is small.

[0032] After the inner liner 1 is manufactured, the outer wall 2 of the inner liner is processed; then the outer wall 2 of the inner liner is coated with a nanoporous insulation material layer 3, and then the nanoporous insulation material layer 3 is coated with a cured resin to form a cured resin layer 4 to strengthen its outermost side to meet the strength requirements for use, and finally wrapped and wound with carbon fiber to form a carbon fiber layer 41 to complete the processing.

[0033] It should be noted that: the head of the gas cylinder liner adopts a standard elliptical head with a certain curved surface; the high-density nanoporous insulation material covered by the head is pressed and formed to be consistent with the curved surface of the head, in order to ensure a perfect fit with the gas cylinder liner head and prevent the nanoporous insulation material from being separated from the curved surface of the head during use; the insulation material and the gas cylinder head must be fixed; therefore, the solution of the present invention adopts a supporting fixing ring to fix the head and the nanomaterial; the material of the supporting fixing ring is annular stainless steel material, and the supporting fixing ring and the gas cylinder head are fixed by argon arc welding, and each head is fixed with three groups of supporting fixing rings; then the nanomaterial and the supporting fixing ring are pressed tightly to prevent the nanoporous insulation material and the inner liner cylinder from shaking against each other.

[0034] In order to find the best material for the nanoporous thermal insulation layer, the following examples are made for comparison.

[0035] Embodiment 1: 53 parts of silicon dioxide, 42 parts of aluminum oxide, 0.8 parts of ferric oxide, 1 part of barium oxide, and 0.5 parts of titanium dioxide are placed in an arc furnace and heated to above 2000°C until they are molten. The melt is thinly streamed and blown into a fibrous material with a high-speed airflow. 60 parts of methyl orthosilicate, 35 parts of hexamethyldisiloxane, 15 parts of deionized water, and 10 parts of hydrochloric acid are mixed and stirred to form a sol through hydrolysis and polycondensation reaction. 8 parts of the above-prepared fibrous material and 18 parts of ammonia water are added. After the polycondensation reaction is allowed to stand and gel, after losing fluidity, 20 parts of anhydrous ethanol are added to age, and then added to an autoclave for supercritical drying and heat preservation. After the ethanol is slowly released and cooled to room temperature, a nano-microporous thermal insulation material can be obtained.

[0036] Embodiment 2: 58 parts of silicon dioxide, 40 parts of aluminum oxide, 0.7 parts of ferric oxide, 1.2 parts of barium oxide and 0.8 parts of titanium dioxide are placed in an arc furnace and heated to above 2000°C to a molten state, and the melt is thinly streamed and blown into a fibrous material with a high-speed airflow. 65 parts of methyl orthosilicate, 30 parts of hexamethyldisiloxane, 20 parts of deionized water and 15 parts of hydrochloric acid are mixed and stirred to generate a sol through hydrolysis and polycondensation reaction, and 8 parts of the above-prepared fibrous material and 15 parts of ammonia water are added. After the polycondensation reaction is allowed to stand and gel, 30 parts of anhydrous ethanol are added for aging, and then the autoclave is added for supercritical drying and heat preservation. After the ethanol is slowly released and cooled to room temperature, a nano-microporous thermal insulation material can be obtained.

[0037] Embodiment 3: 58 parts of silicon dioxide, 40 parts of aluminum oxide, 0.7 parts of ferric oxide, 1.2 parts of barium oxide, and 0.8 parts of titanium dioxide are placed in an arc furnace and heated to above 2000°C to a molten state, and the melt is thinly streamed and blown into a fibrous material with a high-speed airflow. 80 parts of methyl orthosilicate, 20 parts of deionized water, and 15 parts of hydrochloric acid are mixed and stirred to generate a sol through hydrolysis and polycondensation reaction, and 8 parts of the above-prepared fibrous material and 15 parts of ammonia water are added. After the polycondensation reaction is allowed to stand and gel, after losing fluidity, 30 parts of anhydrous ethanol are added to age, and then added to an autoclave for supercritical drying and heat preservation. After slowly releasing the ethanol and cooling to room temperature, a nano-microporous thermal insulation material can be obtained.

[0038] Embodiment 4: 58 parts of silicon dioxide, 40 parts of aluminum oxide, 0.7 parts of ferric oxide and 2 parts of barium oxide are placed in an electric arc furnace and heated to above 2000°C until they are molten. The melt is thinly streamed and blown into a fibrous material with a high-speed airflow. 80 parts of methyl orthosilicate, 20 parts of deionized water and 15 parts of hydrochloric acid are mixed and stirred to form a sol through hydrolysis and polycondensation reaction. 16 parts of the above-prepared fibrous material and 15 parts of ammonia water are added. After the polycondensation reaction is allowed to stand and gel, 30 parts of anhydrous ethanol are added for aging, and then the autoclave is added for supercritical drying and heat preservation. The ethanol is slowly released and then cooled to room temperature to obtain a nano-microporous thermal insulation material.

[0039] Comparative Example: 53 parts of silicon dioxide, 42 parts of aluminum oxide, 0.8 parts of ferric oxide, and 1 part of calcium oxide are placed in an electric arc furnace and heated to above 2000°C until they are molten. The melt is thinly streamed and blown into a fibrous material with a high-speed airflow. 80 parts of methyl orthosilicate, 15 parts of deionized water, and 10 parts of hydrochloric acid are mixed and stirred to form a sol through hydrolysis and polycondensation reaction. 8 parts of the above-prepared fibrous material and 18 parts of ammonia water are added. After the polycondensation reaction is allowed to stand and gel, after losing fluidity, 20 parts of anhydrous ethanol are added for aging, and then the material is placed in an autoclave for supercritical drying and heat preservation. The ethanol is slowly released and then cooled to room temperature to obtain a nano-microporous thermal insulation material.

[0040] The above embodiments all use mass fractions. The thermal insulation materials prepared in the above embodiments were subjected to thermal conductivity test and compression test, respectively, and the experimental data are as follows:

[0041] Comparative Example Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Thermal conductivity W / (m K) 0.015 0.012 0.011 0.013 0.013 Compressive strength MPa 14.2 15.3 15.4 15.0 14.9

[0042] From the above test results, it can be seen that when the reinforcing fiber is a combination of barium oxide and titanium dioxide, the material has the best compressive strength, and when a combination of methyl orthosilicate and hexamethyldisiloxane is used, the thermal conductivity of the material is the lowest. When a combination of barium oxide, titanium dioxide, methyl orthosilicate, and hexamethyldisiloxane is used at the same time, that is, Example 1 and Example 2, the test value as the insulation material for a low-temperature insulation container is the best.

[0043] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Some technical contents well known to ordinary technicians in the field will not be repeated here. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present invention, various modifications or deformations that can be made by technical personnel in this field without creative work are still within the scope of protection of the present invention.

Claims

1. An insulated low-temperature container, comprising an inner liner, wherein the inner liner comprises a cylinder, a front head, and a rear head, characterized in that: The outer wall of the inner liner is provided with a nanoporous insulation material layer, a cured resin layer and a carbon fiber layer in sequence; the nanoporous insulation material layer is calculated by weight, and the preparation method is as follows: 53-58 parts of silicon dioxide, 40-42 parts of aluminum oxide, 0.7-0.8 parts of iron oxide, 1-1.2 parts of barium oxide and 0.5-0.8 parts of titanium dioxide are heated to above 2000°C to a molten state, and the molten stream is blown into a fibrous material, 60-65 parts of methyl orthosilicate, 30-35 parts of hexamethyldisiloxane, 15-20 parts of deionized water and 10-15 parts of hydrochloric acid are mixed and stirred to form a sol through hydrolysis and polycondensation reaction, 8 parts of the above-prepared fibrous material and 15-18 parts of ammonia water are added, and after the polycondensation reaction is allowed to stand and the gel loses fluidity, 20-30 parts of anhydrous ethanol are added, and the sol is dried and kept warm after aging, and the ethanol is released and then cooled to room temperature.

2. The thermally insulated cryogenic container according to claim 1, characterized in that: A supporting and fixing mechanism is arranged on the outer wall of the inner container for fixing the nanoporous thermal insulation material layer.

3. The thermally insulated cryogenic container according to claim 1, characterized in that: The front sealing head and the rear sealing head are both provided with a supporting and fixing mechanism for fixing the nanoporous thermal insulation material layer.

4. The thermally insulated cryogenic container according to claim 1, characterized in that: The front sealing head is connected with an extension pipe, and the extension pipe is provided with a valve.

5. The thermally insulated cryogenic container according to claim 1, characterized in that: A seventh supporting and fixing ring is arranged on the cylinder.

6. The thermally insulated cryogenic container according to claim 1, characterized in that: An eighth supporting and fixing ring is arranged on the cylinder.

7. The thermally insulated cryogenic container according to claim 1, characterized in that: The rear head is provided with a first supporting and fixing ring, a second supporting and fixing ring and a third supporting and fixing ring in sequence from the outside to the center.

8. The thermally insulated cryogenic container according to claim 1, characterized in that: The front head is provided with a fourth supporting and fixing ring, a fifth supporting and fixing ring and a sixth supporting and fixing ring in sequence from the outside to the center.

Images