Mixing heat insulation method for low-temperature storage tank and mixing device thereof

Abstract

The invention relates to a mixing heat insulation method for a low-temperature storage tank and a mixing device thereof. The mixing heat insulation method comprises the following steps: preparing a micro reflective foil: cutting an aluminum foil, a copper foil, a gold foil or a metal-plated organic film into the micro reflective foil, and treating pearlife: carrying out thermal vacuum pure nitrogen replacement treatment in a pearlife storage tank, and then sealing and storing for later use; mixing and proportioning: mixing the pearlife and the foils in proportion, wherein the proportioning principle is to ensure that the foils are dispersed and are in discontinuous contact; mixing and filling; constructing the device; assembling a mixed heat insulation device for the low-temperature storage tank; a mixing process: starting a vacuum pump, and opening a second vacuum quick-release connecting valve to vacuumize a mixing tank; enabling the pearlife and the foil to flow into a mixing tank through pressure difference under the protection of nitrogen, and starting a stirring rotating shaft to uniformly mix the pearlife and the foil; filling a nitrogen protection material which is slightly higher than atmospheric pressure after completion; and filling construction. Through the synergistic effect of the pearlife and the fine reflection foil, the heat insulation performance is remarkably improved, and uniform filling and flexible construction of the mixture are achieved.

Description

Technical Field

[0001] The present invention relates to the field of low-temperature thermal insulation technology, and in particular to a mixed thermal insulation method and a mixing device for low-temperature storage tanks, which are suitable for filling the insulation layer of vacuum or non-vacuum low-temperature storage tanks, air separation equipment and deep-cold equipment. Background Art

[0002] The application and development of cryogenic liquefied gases require the support of efficient and low-cost insulation technology. The storage and transportation of cryogenic liquefied gases (such as liquid nitrogen, liquid oxygen, liquefied natural gas, etc.) rely on efficient insulation technology. Existing technologies mainly include: (1) High vacuum multi-layer insulation: Insulation is achieved by alternately stacking reflective foil and spacer materials. Although it can block some radiation and conduction, it requires maintaining a high vacuum state for a long time. The process is complex and costly, and the manufacturing cycle is long, making it difficult to apply to large equipment.

[0003] (2) Pearlescent sand insulation: The use of porous pearlescent sand to fill the insulation layer has the advantages of low cost and simple process. Because thermal radiation has a transmissive effect on pearlescent sand, it cannot block the heat leakage caused by thermal radiation heat transfer, resulting in the insulation efficiency being about two orders of magnitude lower than that of multi-layer insulation.

[0004] In recent years, research on hybrid insulation materials has gradually increased, such as adding nano-aerogel or carbon fiber to pearlescent sand, but there are the following problems: (1) Insufficient reflective performance: Nanomaterials have limited reflective effect on thermal radiation and poor dispersion.

[0005] (2) Process complexity: Requires complex pretreatment or special equipment, making it difficult to apply on a large scale.

[0006] Therefore, the applicant proposes a hybrid insulation method and a hybrid device for a cryogenic storage tank to solve the above problems. Summary of the Invention

[0007] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a mixed insulation method and mixing device for low-temperature storage tanks. By mixing pearl sand with fine reflective foil, using the high reflectivity of the foil to block thermal radiation, combined with a movable mixing and filling device, the problems of low insulation efficiency, complex process and poor adaptability in the existing technology are solved, and the insulation efficiency is significantly improved by suppressing thermal radiation.

[0008] The object of the present invention is achieved like this: A mixing insulation device for a low-temperature storage tank, comprising a reflective foil storage tank, a mixing tank, a pearlescent sand storage tank, and a pure nitrogen cylinder. The reflective foil storage tank and the pearlescent sand storage tank are respectively connected to the mixing tank, which are respectively connected to the pure nitrogen cylinder via an inflation pipe. The mixing tank is provided with a stirring shaft, a stirring vane, and a heating pipe. The bottom of the mixing tank is funnel-shaped, with a waste discharge valve provided at the lowest point. A finished product discharge pipe is connected to one side of the funnel-shaped bottom of the mixing tank, and a vacuum pump is connected to the other side. A plurality of stirring blades are symmetrically and evenly arranged on the left and right sides of the stirring shaft in the mixing tank. At least one set of heating tubes is provided on the inner wall of the mixing tank, and each set of heating tubes includes two heating tubes symmetrically arranged on the left and right sides of the stirring shaft. The heating tubes are arranged between two stirring blades adjacent to each other, and one end of the heating tubes is fixed to the inner wall of the mixing tank. A layer of fine filter is provided above the waste discharge valve of the mixing tank, and the fine filter is arranged in the funnel-shaped bottom of the mixing tank. A transparent observation window is also provided on the outer wall of the mixing tank. A first vacuum quick-release connection valve is provided on the connecting pipe between the reflective foil storage tank and the mixing tank, a second vacuum quick-release connection valve is provided on the connecting pipe between the vacuum pump and the mixing tank, and a third vacuum quick-release connection valve is provided on the connecting pipe between the pearl sand storage tank and the mixing tank 7.

[0009] Furthermore, a first inflation valve is provided on the inflation pipe connecting the reflective foil storage tank and the pure nitrogen cylinder, and a second inflation valve is provided on the inflation pipe connecting the pearl sand storage tank and the pure nitrogen cylinder.

[0010] Furthermore, a feeding valve is provided on the finished product discharge pipe.

[0011] A hybrid insulation method for a cryogenic storage tank, based on the above-mentioned hybrid insulation device for a cryogenic storage tank, is characterized by comprising the following contents: S1. Material preparation: S1.1. Preparation of fine reflective foil: Cut aluminum foil, copper foil, gold foil or metal-plated organic film into fine reflective foil. S1.2, Pearlescent sand treatment: The newly prepared pearlescent sand is transported to the site in sealed special tanks for use; After the pearl sand is subjected to thermal vacuum pure nitrogen replacement treatment in the pearl sand storage tank, it is sealed and stored for future use; S2. Mixing ratio: Mix the pearl sand and foil in proportion. The mixing principle is to ensure that the foil is dispersed and not in continuous contact. S3. Mixing and filling: S3.1. Device construction: Assemble a mixing insulation device for low-temperature storage tanks, and connect the discharge port of the fine reflective foil storage tank and the discharge port of the pearlescent sand storage tank to the feed port of the mixing processing tank through vacuum quick-release connection valves; S3.2, Mixing process: S3.21. Turn on the vacuum pump and open the second vacuum quick-release valve to create a low vacuum in the mixing tank. S3.22. Under nitrogen protection, pearl sand and foil flow into the mixing tank through pressure difference, and the stirring shaft is turned on; S3.23. Monitor the mixing uniformity through the observation window. Maintain or adjust the third and first vacuum quick-release valves according to the mixing state until the mixing ratio is uniform. After feeding is completed, observe the mixing uniformity through the observation window and stop stirring. S3.24. After completion, fill the material with nitrogen at a pressure slightly higher than atmospheric pressure; S4. Filling construction: For vacuum equipment: fill the mixture into the insulation layer by vacuum suction method, supplemented by vibration compaction; For non-vacuum equipment: Move the mixing tank to the site and fill it with the foil and pearl sand mixture by gravity pouring.

[0012] Furthermore, the fine reflective foil in step S1.1 can be cut into any irregular pieces of circles, triangles or polygons with a side length / diameter of 0.5-1.5 mm. The production process should be kept dry and clean to prevent the foil from being contaminated by water stains, oil stains, etc. The prepared fine reflective foil is stored in a dry nitrogen environment.

[0013] Furthermore, in step S1.2, the reserved pearlescent sand is placed in a sealed tank, and after being heated to above 200°C and vacuumed to better than 10Pa, pure nitrogen is filled in to atmospheric pressure, and then the tank is evacuated and replaced repeatedly for several times, and then filled with pure nitrogen for more than 4 hours for standby use.

[0014] Furthermore, the reference proportions of the various fine foils in step S2 are: the proportion of mixed aluminum-plated film in pearl sand is 200g of foil / cubic meter of pearl sand, the proportion of mixed aluminum foil in pearl sand is 500g of foil / cubic meter of pearl sand, the proportion of mixed copper foil in pearl sand is 1500g of foil / cubic meter of pearl sand, the proportion of mixed silver foil in pearl sand is 2000g of foil / cubic meter of pearl sand, and the proportion of mixed gold foil in pearl sand is 3000g of foil / cubic meter of pearl sand.

[0015] Furthermore, in step S3.21, the vacuum pump draws the mixture into the mixing tank to a low vacuum of ≤100 Pa.

[0016] Furthermore, in step S3.22, the stirring rotor is mixed at a uniform speed of 60-120 rpm for 10-15 minutes, and the stirring rotor is kept rotating steadily and uniformly.

[0017] Furthermore, in step S3.24, pure nitrogen is controlled by a pure nitrogen cylinder and a pressure reducing valve, and the pure nitrogen is filled into the mixing tank through the inflation pipe, the inflation valve, and the first vacuum quick-release connecting valve to maintain a pressure slightly higher than the ambient atmospheric pressure, so as to facilitate the filling of the thermal insulation interlayer of the cryogenic storage tank or equipment.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a hybrid insulation method and device for cryogenic storage tanks, which have the following specific advantages: (1) Improved insulation efficiency: The reflective foil blocks more than 90% of thermal radiation, and the thermal conductivity of the mixed insulation layer is greatly reduced.

[0019] (2) Construction flexibility: The movable mixing tank supports on-site filling and is suitable for large storage tanks and complex equipment.

[0020] (3) Cost advantage: No high vacuum equipment is required, which reduces material costs.

[0021] (4) Wide compatibility: Suitable for various reflective materials such as aluminum foil, copper foil, and metal-plated film. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the hybrid insulation device of the present invention.

[0023] Figure 2 Schematic diagram of the process of the hybrid insulation method of the present invention.

[0024] in: Pressure reducing valve 1, inflation pipe 2, first inflation valve 3, reflective foil storage tank 4, first vacuum quick-release connecting valve 5, stirring shaft 6, mixing tank 7, stirring vane 8, heating tube 9, second vacuum quick-release connecting valve 10, vacuum pump 11, observation window 12, waste discharge valve 13, fine filter 14, finished product discharge pipe 15, feeding valve 16, third vacuum quick-release connecting valve 17, pearl sand storage tank 18, second inflation valve 19, pure nitrogen cylinder 20. DETAILED DESCRIPTION

[0025] To better understand the technical solution of the present invention, the following detailed description is provided with reference to the relevant illustrations. It should be understood that the following specific embodiments are not intended to limit the specific implementation of the technical solution of the present invention; they are merely examples of possible implementations of the technical solution of the present invention. It should be noted that references herein to the positional relationships of various components, such as component A being located above component B, are based on the relative positions of the components in the illustrations and are not intended to limit the actual positional relationships of the components. Example 1

[0026] See also Figure 1-2 , Figure 1 A drawing shows a hybrid insulation device for a cryogenic storage tank according to the present invention. As shown, the device comprises a reflective foil storage tank 4, a mixing tank 7, a pearlescent sand storage tank 18, and a pure nitrogen cylinder 20. The reflective foil storage tank 4 and the pearlescent sand storage tank 18 are each connected to the mixing tank 7, which is in turn connected to the pure nitrogen cylinder 20 via an air charging pipe 2. The mixing tank 7 is provided with a stirring shaft 6, stirring vanes 8, and a heating pipe 9. The mixing tank 7 has a funnel-shaped bottom with a waste discharge valve 13 at its lowest point. A finished product discharge pipe 15 is connected to one side of the funnel-shaped bottom of the mixing tank 7, and a vacuum pump 11 is connected to the other side.

[0027] A number of stirring blades 8 are symmetrically and evenly arranged on the left and right sides of the stirring shaft 6 in the mixing tank 7. At least one group of heating tubes 9 is provided on the inner wall of the mixing tank 7. Each group of heating tubes 9 includes two heating tubes 9 symmetrically arranged on the left and right sides of the stirring shaft 6. The heating tube 9 is arranged between two adjacent stirring blades 8 above and below, and one end of the heating tube 9 is fixed on the inner wall of the mixing tank 7.

[0028] A layer of fine filter mesh 14 is provided above the waste discharge valve 13 of the mixing tank 7 , and the fine filter mesh 14 is arranged in the funnel-shaped bottom of the mixing tank 7 .

[0029] A transparent observation window 12 is also provided on the outer wall of the mixing tank 7 .

[0030] A first inflation valve 3 is provided on the inflation pipe 2 connecting the reflective foil storage tank 4 and the pure nitrogen cylinder 20 , and a second inflation valve 19 is provided on the inflation pipe connecting the pearl sand storage tank 18 and the pure nitrogen cylinder 20 .

[0031] A first vacuum quick-release connecting valve 5 is provided on the connecting pipe between the reflective foil storage tank 4 and the mixing tank 7, a second vacuum quick-release connecting valve 10 is provided on the connecting pipe between the vacuum pump 11 and the mixing tank 7, and a third vacuum quick-release connecting valve 17 is provided on the connecting pipe between the pearlescent sand storage tank 18 and the mixing tank 7; the first vacuum quick-release connecting valve 5, the second vacuum quick-release connecting valve 10 and the third vacuum quick-release connecting valve 17 realize the rapid separation of the mixing tank from each storage tank and the vacuum pump, and are suitable for different construction scenarios.

[0032] The finished product discharge pipe 15 is provided with a feeding valve 16 .

[0033] The pure nitrogen cylinder 20 is connected to the reflective foil storage tank 4 and the pearlescent sand storage tank 18 through the inflation pipe 2 to form a nitrogen system, which prevents the material from absorbing harmful gases such as water vapor and improves the insulation stability.

[0034] See also Figure 2 , Figure 2 A hybrid insulation device for a cryogenic storage tank according to the present invention is shown. As shown in the figure, a hybrid insulation method for a cryogenic storage tank includes the following: S1. Material preparation: S1.1. Preparation of fine reflective foil: Cut aluminum foil, copper foil, gold foil or metal-plated organic film into fine reflective foil. The fine reflective foil can be cut into any irregular pieces such as circles, triangles or polygons with a side length / diameter of 0.5-1.5 mm. Keep the foil dry and clean during the production process to prevent it from being contaminated by water stains, oil stains, etc. The prepared fine reflective foil is stored in a dry nitrogen environment. S1.2, Pearlescent sand treatment: The newly prepared pearlescent sand is transported to the site in sealed special tanks for use; The pearl sand is placed in a storage tank for thermal vacuum and pure nitrogen replacement before use; Place the reserved pearlescent sand in a sealed tank, heat it to above 200℃ and evacuate it to a vacuum better than 10Pa, then fill it with pure nitrogen to atmospheric pressure, continue evacuating the air, repeatedly replace it several times, and then fill it with pure nitrogen for more than 4 hours in the evacuated state for standby use; S2. Mixing ratio: Mix the pearl sand and foil according to the ratio in Table 1 (the ratio can be increased or decreased according to the mixing principle and the implementation object). When mixing, ensure that the foil is dispersed and not in continuous contact.

[0035] Fine foil materials Reference ratio (gram foil / cubic meter of pearlescent sand) Aluminum film 200 g aluminum foil 500 g copper foil 1500 g silver foil 2000 g gold foil 3000 g Table 1. Reference ratio of various fine foils S3. Mixing and filling: S3.1. Device construction: Assemble the above-mentioned mixing insulation device for low-temperature storage tanks, and connect the discharge port of the fine reflective foil storage tank and the discharge port of the pearlescent sand storage tank to the feed port of the mixing treatment tank through vacuum quick-release connection valves; S3.2, Mixing process: S3.21. Turn on the vacuum pump and open the second vacuum quick-release valve to create a low vacuum in the mixing tank. The vacuum pump draws vacuum into the mixing tank until it reaches a low vacuum (≤100 Pa). S3.22. Under nitrogen protection, flow the pearlescent sand and foil into the mixing tank through a pressure differential. Turn on the stirring shaft and mix at a constant speed of 60-120 rpm for 10-15 minutes, keeping the stirring blade rotating steadily and at a constant speed. S3.23. Monitor the mixing uniformity through the observation window. Maintain or adjust the third and first vacuum quick-release valves according to the mixing state until the mixing ratio is uniform. After feeding is completed, observe the mixing uniformity through the observation window and stop stirring. S3.24. After completion, fill the material with nitrogen at a pressure slightly higher than atmospheric pressure; The pure nitrogen is controlled by a pure nitrogen cylinder and a pressure reducing valve, and is filled into the mixing tank through the charging pipe, the charging valve, and the first vacuum quick-release connecting valve to maintain a slightly higher pressure than the ambient atmospheric pressure, so as to facilitate the filling of the thermal insulation interlayer of the low-temperature storage tank or equipment.

[0036] S4. Filling construction: S4.1. Vacuum equipment: Fill the mixture into the insulation layer by vacuum suction method, supplemented by vibration compaction; For filling vacuum low-temperature storage tanks, air separation and cryogenic equipment, the conventional vacuum suction method can be used, that is, vacuuming the insulation interlayer of the low-temperature storage tank or equipment to suck the material in the mixing tank into the insulation interlayer of the vacuum low-temperature storage tank, air separation and cryogenic equipment; at the same time, the air pressure method or the wall tapping vibration method of different frequencies are used to evenly compact the material; Connect the finished product discharge pipe interface of the mixing tank to the vacuum low-temperature storage tank, air separation and cryogenic equipment process interface that needs to be filled with fine foil and pearl sand mixed insulation, and check that the connection surface is airtight and leak-free; Connect the vacuum pump to the vacuum low-temperature storage tank, air separation and deep-freeze equipment evacuation port. The evacuation port must be equipped with a filter to prevent powder from entering the vacuum pump. Open the low vacuum pump and the feeding valve, and the mixture of foil and pearl sand will automatically enter the vacuum low-temperature storage tank, air separation and cryogenic equipment insulation layer; After filling, the empty space is continued to be filled by using air pressure method or wall tapping vibration method of different frequencies, and vibration is continued until the material is evenly and densely filled.

[0037] S4.2, Non-vacuum equipment: Move the mixing tank to the site and fill it with the foil and pearl sand mixture by gravity pouring; For the filling of non-vacuum cryogenic storage tanks, air separation and cryogenic equipment, the pouring method is adopted; first, the mixing tank is separated and sealed from the vacuum pump through the second vacuum quick-release connection valve; the pearl sand storage tank is isolated and sealed from the mixing tank through the third vacuum quick-release connection valve; after the cylinder pure nitrogen is filled with pure nitrogen slightly above atmospheric pressure through the pressure reducing valve, the charging pipe, the first charging valve, and the first vacuum quick-release connection valve, the reflective foil storage tank is separated from the mixing tank through the first vacuum quick-release connection valve; the mixing tank becomes a movable tank body, and then the mixing tank is placed above the interface of the non-vacuum cryogenic storage tank, air separation and cryogenic equipment to be filled; Connect the diameter of the finished product feeding pipe to the filling port of the storage tank or equipment to be filled, open the feeding valve, and allow the material to flow naturally into the thermal insulation interlayer of the non-vacuum low-temperature storage tank or equipment through the feeding pipe; the material can be kept flowing smoothly into the thermal insulation interlayer of the non-vacuum low-temperature storage tank or equipment by rotating the stirring vane or opening the first vacuum quick-release connection valve. After filling, use the wall tapping vibration method of different frequencies to add the material to the excess space until it is evenly dense; it is not recommended to use the air pressure method to avoid dust splashing.

[0038] Specific implementation case (filling the insulation layer of liquid nitrogen storage tank): 1. Material preparation: The pearl sand was treated by vacuum nitrogen replacement, and the aluminum-coated film was cut into 1 mm irregular pieces (ratio 200 g / cubic meter).

[0039] 2. Mixing process: The mixing tank was evacuated to 80 Pa, and the pearl sand and foil were mixed under nitrogen for 12 minutes at a stirring speed of 80 rpm.

[0040] 3. Filling verification Comparative case (non-vacuum insulation transformation of air separation equipment): 1. On-site construction: The mixing tank is moved to the equipment site and filled with copper foil mixture by gravity pouring method (ratio: copper foil 1500 g / pearl sand m 3 ); 1500 g of copper foil per cubic meter of pearl sand.

[0041] 2. Effect evaluation: After filling the liquid nitrogen storage tank insulation layer, the actual measurement of liquid nitrogen evaporation rate shows that the insulation performance is 35% higher than that of pure pearl sand insulation.

[0042] Working principle: The present invention provides a mixed insulation method and a mixing device for a low-temperature storage tank. The functions and applications of the various components of the mixing device (i.e., a device for mixing and filling fine reflective foil and pearlescent sand) are as follows: 1. Vacuum System: The vacuum pump provides a low vacuum environment to the mixing tank via the second vacuum quick-release valve, allowing the materials in the pearlescent sand storage tank and reflective foil storage tank to be transported into the mixing tank due to gas flow. The second vacuum quick-release valve is connected via a vacuum quick-release connector. After the materials are mixed and vacuum-heated, the vacuum pump can be easily separated from the mixing tank via the second vacuum quick-release connector, making the mixing tank a free and mobile tank.

[0043] 2. Mixing monitoring: The mixing shaft drives the mixing vane to rotate to mix the materials, and the mixing status is observed through the observation window. When the requirements are met, the mixing shaft is controlled to stop.

[0044] 3. Filtration setting: The function of the fine filter is to allow the fine powder generated during the mixing process to enter the bottom of the mixing tank through the fine filter. Pure nitrogen with a pressure slightly higher than atmospheric pressure is then filled into the mixing tank through the pressure reducing valve, and the fine powder is discharged through the waste discharge valve. 4. Pure Nitrogen System: The pure nitrogen system isolates the air and provides a pure airflow; pure nitrogen protects and displaces the materials. During the mixing phase, the pure nitrogen cylinder, controlled by a pressure reducing valve, is fed through a charging pipe and valve to the reflective foil storage tank, mixing tank, and pearlescent sand storage tank, replenishing the pure nitrogen lost due to vacuuming. At the end of mixing, pure nitrogen is filled to a pressure slightly above ambient atmospheric pressure through the pressure reducing valve to protect the materials within the mixing tank. If purification of the materials within the mixing tank is required, a vacuum pump is used to evacuate the tank, a heating pipe is used to heat the mixture, and pure nitrogen is filled through the pressure reducing valve to displace and purify the materials. This further improves the efficiency of the vacuuming operation and thermal insulation performance after material loading.

[0045] 5. Feeding system: The feeding system is connected to the mixing tank by the third vacuum quick-release connector and the first vacuum quick-release connector. When the mixing is completed, the pearl sand storage tank and the reflective foil storage tank can be easily separated from the mixing tank through the vacuum quick-release connector, making the mixing tank an independent and freely movable tank.

[0046] Hybrid insulation method: Step 1: Build a mixing and loading device for the fine reflective foil and pearlescent sand. This mixing and loading device is characterized by its convenient assembly, allowing for mixing materials in a fixed location. After mixing, the mixing and loading device can be easily disassembled into a mobile device for use in different locations and cryogenic storage tanks.

[0047] Step 2: Cut aluminum foil, copper, silver, gold or other metal foils or aluminum-plated organic thin film reflective materials into fine reflective foils of any shape.

[0048] Step 3: Mix the fine reflective foil according to the volume of pearl sand and the mass of the fine reflective foil. The ratio is given in Table 1.

[0049] Step 4: Use a device for mixing and filling fine reflective foil and pearlescent sand, and evenly mix the fine reflective foil and pearlescent sand in a mixing tank of the device according to a mixing procedure.

[0050] Step 5: Load the uniformly mixed material in the mixing and filling device into the insulation layer of the low-temperature storage tank, air separation and cryogenic equipment; or after the mixing and filling device is conveniently disassembled, the mixing tank is transported as a movable material container to the large storage tank, air separation and cryogenic equipment site for filling.

[0051] In summary, this method achieves efficient filling of the insulation layer by mixing fine reflective foil and pearlescent sand in appropriate proportions, leveraging the foil's high reflectivity to block thermal radiation. This method, combined with a mobile mixing and filling device, improves insulation efficiency by over 30%, offers flexible construction and low cost, and is suitable for both vacuum and non-vacuum cryogenic storage tanks, air separation plants, and cryogenic equipment.

[0052] The above are only specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. Any technical solutions formed by equivalent transformation or equivalent replacement shall fall within the scope of protection of the present invention.

Claims

1. A hybrid insulation device for a cryogenic storage tank, characterized by: It comprises a reflective foil storage tank (4), a mixing tank (7), a pearl sand storage tank (18) and a pure nitrogen cylinder (20), wherein the reflective foil storage tank (4) and the pearl sand storage tank (18) are respectively connected to the mixing tank (7), and the reflective foil storage tank (4) and the pearl sand storage tank (18) are respectively connected to the pure nitrogen cylinder (20) via an air charging pipe (2). The mixing tank (7) is provided with a stirring shaft (6), a stirring rotor (8) and a heating pipe (9). The bottom of the mixing tank (7) is funnel-shaped, and a waste discharge valve (13) is provided at the lowest point. One side of the funnel-shaped bottom of the mixing tank (7) is connected to a finished product discharge pipe (15), and the other side is connected to a vacuum pump (11). A plurality of stirring blades (8) are symmetrically arranged on the left and right sides of the stirring shaft (6) in the mixing tank (7), and at least one group of heating tubes (9) is provided on the inner wall of the mixing tank (7). Each group of heating tubes (9) includes two heating tubes (9) symmetrically arranged on the left and right sides of the stirring shaft (6). The heating tube (9) is arranged between two stirring blades (8) adjacent to each other in the upper and lower directions. One end of the heating tube (9) is fixed on the inner wall of the mixing tank (7); a layer of fine filter (14) is provided above the waste discharge valve (13) of the mixing tank (7), and the fine filter (14) is provided in the funnel-shaped bottom of the mixing tank (7); and a transparent observation window (12) is also provided on the outer wall of the mixing tank (7); A first vacuum quick-release connection valve (5) is provided on the connection pipe between the reflective foil storage tank (4) and the mixing tank (7), a second vacuum quick-release connection valve (10) is provided on the connection pipe between the vacuum pump (11) and the mixing tank (7), and a third vacuum quick-release connection valve (17) is provided on the connection pipe between the pearlescent sand storage tank (18) and the mixing tank (7).

2. A mixing device for a cryogenic storage tank according to claim 1, characterized in that: A first inflation valve (3) is provided on the inflation pipe (2) connecting the reflective foil storage tank (4) and the pure nitrogen cylinder (20), and a second inflation valve (19) is provided on the inflation pipe connecting the pearlescent sand storage tank (18) and the pure nitrogen cylinder (20).

3. The mixing device for a cryogenic storage tank according to claim 1, characterized in that: The finished product discharge pipe (15) is provided with a feeding valve (16).

4. A hybrid insulation method for a cryogenic storage tank, based on the hybrid insulation device for a cryogenic storage tank according to claim 1, characterized in that: Includes the following: S1. Material preparation: S1.

1. Preparation of fine reflective foil: Cut aluminum foil, copper foil, gold foil or metal-plated organic film into fine reflective foil. S1.2, Pearlescent sand treatment: The newly prepared pearlescent sand is transported to the site in sealed special tanks for use; After the pearl sand is subjected to thermal vacuum pure nitrogen replacement treatment in the pearl sand storage tank, it is sealed and stored for future use; S2. Mixing ratio: Mix the pearl sand and foil in proportion. The mixing principle is to ensure that the foil is dispersed and not in continuous contact. S3. Mixing and filling: S3.

1. Device construction: Assemble a mixing insulation device for low-temperature storage tanks, and connect the discharge port of the fine reflective foil storage tank and the discharge port of the pearlescent sand storage tank to the feed port of the mixing processing tank through vacuum quick-release connection valves; S3.2, Mixing process: S3.

21. Turn on the vacuum pump and open the second vacuum quick-release valve to create a low vacuum in the mixing tank. S3.

22. Under nitrogen protection, pearl sand and foil flow into the mixing tank through pressure difference, and the stirring shaft is turned on; S3.

23. Monitor the mixing uniformity through the observation window. Maintain or adjust the third and first vacuum quick-release valves according to the mixing state until the mixing ratio is uniform. After feeding is completed, observe the mixing uniformity through the observation window and stop stirring. S3.

24. After completion, fill the material with nitrogen at a pressure slightly higher than atmospheric pressure; S4. Filling construction: For vacuum equipment: fill the mixture into the insulation layer by vacuum suction method, supplemented by vibration compaction; For non-vacuum equipment: Move the mixing tank to the site and fill it with the foil and pearl sand mixture by gravity pouring.

5. A hybrid insulation method for a cryogenic storage tank according to claim 4, characterized in that: The fine reflective foil in step S1.1 can be cut into any irregular pieces such as circles, triangles, or polygons with a side length / diameter of 0.5-1.5 mm. The production process should be kept dry and clean to prevent the foil from being contaminated by water stains, oil stains, etc. The prepared fine reflective foils were stored in a dry nitrogen environment.

6. The hybrid insulation method for a cryogenic storage tank according to claim 4, characterized in that: In step S1.2, the reserved pearlescent sand is placed in a sealed tank, heated to above 200°C and vacuumed to better than 10Pa, filled with pure nitrogen to atmospheric pressure, and then continued to evacuate the air. After repeated replacement several times, the tank is filled with pure nitrogen for more than 4 hours in the evacuated state for standby use.

7. The hybrid insulation method for a cryogenic storage tank according to claim 4, characterized in that: Reference proportions of various fine foils in step S2: the ratio of aluminum-plated film mixed in pearl sand is 200g of foil per cubic meter of pearl sand, the ratio of aluminum foil mixed in pearl sand is 500g of foil per cubic meter of pearl sand, the ratio of copper foil mixed in pearl sand is 1500g of foil per cubic meter of pearl sand, the ratio of silver foil mixed in pearl sand is 2000g of foil per cubic meter of pearl sand, and the ratio of gold foil mixed in pearl sand is 3000g of foil per cubic meter of pearl sand.

8. The hybrid insulation method for a cryogenic storage tank according to claim 4, characterized in that: In step S3.21, the vacuum pump draws the mixture into the mixing tank to a low vacuum of ≤100 Pa.

9. The hybrid insulation method for a cryogenic storage tank according to claim 4, characterized in that: In step S3.22, the stirring rotor is stirred at a constant speed of 60-120 rpm for 10-15 minutes, and the stirring rotor is kept rotating steadily and at a constant speed.

10. The hybrid insulation method for a cryogenic storage tank according to claim 4, characterized in that: In step S3.24, pure nitrogen is controlled by a pure nitrogen cylinder and a pressure reducing valve, and is filled into the mixing tank through the filling pipe, the filling valve, and the first vacuum quick-release connecting valve to maintain a pressure slightly higher than the ambient atmospheric pressure, so as to facilitate the filling of the thermal insulation interlayer of the low-temperature storage tank or equipment.

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