Preparation method and preparation device of aerogel powder

Abstract

The present invention relates to a method and device for preparing aerogel powder. The method comprises steps of preparing a modified silica sol, preparing a coagulant liquid, spraying gel granulation, and vacuum drying. By configuring the preparation device and performing specific settings on each step, in conjunction with parameter settings of each step, an aerogel powder product with balanced performance parameters is obtained. This avoids the problems of dust pollution and high energy consumption caused by mechanical crushing of the aerogel, shortens the path of alcohol drying and separation, and reduces the problem of SiO2 wet gel skeleton collapse caused by capillary force. This technical route greatly shortens the production cycle and reduces material costs, and has huge market prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical coatings, and further to the technical field of aerogels, and in particular to a method and a device for preparing aerogel powder. Background Art

[0002] SiO2 aerogel is a solid material with a three-dimensional nanoporous structure composed of stacked nanoparticles. It has the characteristics of chemical inertness, thermal insulation, sound insulation and noise reduction, shock absorption and energy absorption, and selective adsorption. It has been widely used in industrial insulation and energy saving, power battery safety and fire protection, automobile energy saving and sound insulation, building energy saving, spacecraft insulation and cold preservation, refrigerator cold preservation and other fields. The existing SiO2 aerogel industrialization has the following problems: the price of organic silicon sources (methyl orthosilicate, ethyl orthosilicate, etc.) fluctuates greatly, and production capacity is greatly affected by the single crystal silicon industry; the price of organic silane modifiers (trimethylchlorosilane, hexamethyldisilazane, etc.) is expensive, which greatly increases the production cost of SiO2 aerogel; SiO2 aerogel prepared by supercritical drying process is limited by equipment and production capacity, and it is difficult to meet the growing market demand; the conventional atmospheric pressure drying process to prepare SiO2 aerogel requires cumbersome solvent replacement steps, long production cycle and high cost.

[0003] Chinese invention patent publication CN108584965A discloses a method for rapidly preparing aerogels by accelerated solvent extraction. By applying accelerated solvent extraction technology to aerogel production, problems such as aging, water washing and desalination, and solvent replacement are solved. Chinese invention patent publication CN108862285A discloses a method for rapidly preparing aerogels by normal pressure accelerated solvent extraction. By performing normal pressure drying based on accelerated solvent extraction technology, the cost is reduced. Chinese invention patent publication CN108751206A discloses a method for rapidly preparing aerogels by variable pressure accelerated solvent extraction. By varying the pressure to accelerate the solvent extraction time, the time is shortened. The above-mentioned processes solve some problems from a certain perspective, but the effect needs to be further improved. Summary of the Invention

[0004] In response to the problems existing in the above-mentioned existing aerogel preparation process, the present invention uses silica sol as a precursor to solve the problems of limited production capacity of organic silicon source and cumbersome post-hydrophobic modification process, and proposes a method and preparation device for aerogel powder.

[0005] This is specifically achieved through the following technical solutions:

[0006] A device for preparing aerogel powder is provided. The device is an atomizing and drying processing device, comprising: a feeding mechanism, a high-pressure atomizing spray disc, an atomizing chamber, an atomizing chamber bottom cone, a high-pressure centrifugal fan, a primary filter, a cyclone, a powder collecting tank I, a powder collecting tank II, a pneumatic valve I, a pneumatic valve II, a vacuum dryer, a gas-liquid separation and recovery device, a powder collecting tank IV, a liquid collecting tank III, an exhaust gas absorption component, and a pneumatic valve III.

[0007] The feeding mechanism is arranged at the top of the atomizing chamber, the high-pressure atomizing spray disc is placed at the top of the atomizing chamber and at the side bottom of the feeding mechanism, and the bottom cone of the atomizing chamber is located at the bottom of the atomizing chamber; the atomizing chamber is connected to the tail gas absorption component and the high-pressure centrifugal fan through pipelines, the outlet end of the high-pressure centrifugal fan is connected to the pneumatic valve I and the primary filter respectively, the bottom end of the primary filter is connected to the powder collecting tank II, the bottom cone of the atomizing chamber is connected to the cyclone through a pipeline, and the cyclone is connected to the primary filter and the powder collecting tank I respectively through pipelines; the pneumatic valve I is respectively connected to the secondary filter and the pneumatic valve II in the gas-liquid separation and recovery device, the pneumatic valve II is respectively connected to the liquid collecting tank III and the vacuum dryer in the gas-liquid separation and recovery device, and the vacuum dryer is respectively connected to the pneumatic valve II and the pneumatic valve III through pipelines.

[0008] The bottom end of the secondary filter in the gas-liquid separation and recovery device is provided with the powder collecting tank III, the top end of the secondary filter is connected to the vacuum pump through a pipeline, the vacuum pump is connected to the gas storage component, the bottom end of the gas storage component is connected with the liquid collecting tank I, the gas storage component is connected to the dry cooling cryogenic refrigerator through a pipeline, the bottom end of the dry cooling cryogenic refrigerator is connected with the liquid collecting tank II, the dry cooling cryogenic refrigerator is connected to the refrigeration unit through the provided circulating gas interface, the dry cooling cryogenic refrigerator is respectively connected to the powder collecting tank IV and the pneumatic valve III through pipelines, and the bottom of the powder collecting tank IV is connected to the liquid collecting tank III; the pneumatic valve III is connected to the high-pressure pump through a pipeline, and the high-pressure pump is connected to the high-pressure gas storage (that is, the hollow cavity with a volume shape of the high-pressure gas storage).

[0009] Preferably, an overflow bypass is provided in the atomization chamber, and the gas-liquid mixture exceeding the capacity of the atomization chamber enters the gas-liquid separation and recovery device through the overflow bypass, and the gas-liquid separation and recovery device comprises a secondary filter, a powder collecting tank III, a vacuum pump, a gas storage component, a liquid collecting tank I, a dry cooling cryogenic refrigerator, a refrigeration unit, a liquid collecting tank II, a high-pressure pump and a high-pressure gas storage; the gas-liquid mixture from the overflow bypass is first purified by the secondary filter, and the powder therein will remain in the powder collecting tank III, and the filtered gas-liquid mixture enters the gas storage component through the vacuum pump, and part of the liquid is discharged under the action of gravity and temperature gradient. The remaining gas-liquid mixture enters the liquid collecting tank I, and enters the heat exchange system composed of a dry cooling cryogenic refrigerator and a refrigeration unit for dry cooling and cryogenic treatment. In the heat exchange process, the saturated vapor of the volatile matter is condensed, and the volatile matter is converted from vapor to liquid. The liquid enters the liquid collecting tank II, and low-temperature gas is obtained at the same time. The gas is pressurized by a high-pressure pump and then filled into a high-pressure gas storage. The gas in the high-pressure gas storage enters the spray gel granulation step for reuse. The liquid obtained in the liquid collecting tank I and the liquid collecting tank II is also purified and enters the spray gel granulation step for reuse.

[0010] A method for preparing aerogel powder comprises the following steps:

[0011] (1) Preparation of modified silica sol: silica sol, dissolution aid diluent and modifier are uniformly mixed to obtain modified silica sol, wherein the mass ratio of silica sol, dissolution aid diluent and modifier is 1: (1-3.5): (0.05-0.3).

[0012] (2) Preparation of a coagulant solution: uniformly mixing the catalyst and the dissolving and diluting agent to obtain a coagulant solution; wherein the mass ratio of the catalyst to the dissolving and diluting agent is 1:(1-20).

[0013] (3) Spray gel granulation: the modified silica sol obtained in step (1) and the coagulant obtained in step (2) are mixed evenly, and after gelation treatment for 15 minutes to 6 hours, the obtained gel is pre-crushed into particles with a particle size of less than 3 mm, and then fed into the atomization chamber by a feeding mechanism. The gel powder obtained is obtained by atomization treatment, and the particle size of the obtained gel powder is 1 to 50 microns. The bottom of the atomization chamber is filled with an alcohol solution, and the gel powder falls into the alcohol solution at the bottom of the atomization chamber under the action of gravity. The gel powder is immersed in the alcohol solution to perform solvent replacement; the atomization treatment is inert gas atomization, liquid atomization, vibrating disk atomization or centrifugal atomization, and the temperature of the atomization treatment is 20 to 50°C. (A preferred embodiment here is: the spray angle during atomization is horizontal and relatively arranged, the distance between the relatively arranged nozzles is 0.3 to 1.0 meters, the temperature in the closed container is 60 to 65°C, the bottom of the closed container is the alcohol solution, and the temperature of the alcohol solution is 55 to 65°C.)

[0014] (3') pH adjustment: Add a catalyst to the alcohol solution containing the gel powder obtained in step (3) to adjust the pH of the gel powder to 6.8-7.2. The pH adjustment soaking time is 2-4 hours. (This step is optional and preferred)

[0015] (4) Vacuum drying: The gel powder obtained in step (3) or step (3') and the alcohol solution are subjected to solid-liquid separation, and then the solid matter (wet gel) is vacuum dried, first at a temperature of 40 to 70°C for 1 to 2 hours, and then at a temperature of 100 to 120°C for 1 to 2 hours to obtain an aerogel powder product; at the same time, the alcohol solution obtained by drying is transferred to step (3) and reused as the alcohol solution for purification in step (3).

[0016] (5) An overflow bypass is provided in the atomization chamber, and the gas-liquid mixture exceeding the capacity of the atomization chamber enters the gas-liquid separation and recovery device through the overflow bypass, and the gas-liquid separation and recovery device comprises a secondary filter, a powder collecting tank III, a vacuum pump, a gas storage component, a liquid collecting tank I, a dry cooling cryogenic refrigerator, a refrigeration unit, a liquid collecting tank II, a high-pressure pump and a high-pressure gas storage; the gas-liquid mixture coming in from the overflow bypass is first purified by the secondary filter, and the powder is discharged into the powder collecting tank III, and the filtered gas-liquid mixture enters the gas storage component through the vacuum pump, and part of the liquid is discharged under the influence of gravity and temperature. Under the action of the gradient, it enters the liquid collecting tank I, and the remaining gas-liquid mixture enters the heat exchange system composed of a dry cooling cryogenic refrigerator and a refrigeration unit for dry cooling and cryogenic treatment. The volatile matter of the saturated steam in the heat exchange system is condensed and converted from vapor to liquid. The liquid enters the liquid collecting tank II, and low-temperature gas is obtained at the same time. The gas is pressurized by a high-pressure pump and then filled into a high-pressure gas storage. The gas in the high-pressure gas storage can enter step (3) for reuse. The liquid obtained in the liquid collecting tank I and the liquid collecting tank II can also be purified and then enter step (3) for reuse.

[0017] Preferably, steps (3) to (5) use the above-mentioned atomization and drying treatment device, which includes: a feeding mechanism, a high-pressure atomization spray disc, an atomization chamber, an atomization chamber bottom cone, a high-pressure centrifugal fan, a primary filter, a cyclone, a powder collecting tank I, a powder collecting tank II, a pneumatic valve I, a pneumatic valve II, a vacuum dryer, a gas-liquid separation and recovery device, a powder collecting tank IV, a liquid collecting tank III, an exhaust gas absorption component and a pneumatic valve III.

[0018] Alternatively, the spray gel granulation in step (3) is replaced by mechanical crushing granulation, and the specific steps are: the modified silica sol obtained in step (1) and the coagulant obtained in step (2) are mixed evenly, and after gel treatment for 15 minutes to 6 hours, the obtained gel is crushed into wet gel powder with a particle size of 30 to 150 microns using a mechanical stirring and crushing equipment.

[0019] Preferably, the feeding mechanism is arranged at the top of the atomizing chamber, the high-pressure atomizing spray disc is placed at the top of the atomizing chamber and at the side bottom of the feeding mechanism, and the atomizing chamber bottom cone is located at the bottom of the atomizing chamber; the atomizing chamber is connected to the tail gas absorption component and the high-pressure centrifugal fan through pipelines, the outlet end of the high-pressure centrifugal fan is respectively connected to the pneumatic valve I and the primary filter, the bottom end of the primary filter is connected to the powder collecting tank II, the atomizing chamber bottom cone is connected to the cyclone through a pipeline, and the cyclone is respectively connected to the primary filter and the powder collecting tank I through pipelines; the pneumatic valve I is respectively connected to the secondary filter and the pneumatic valve II in the gas-liquid separation and recovery device, the pneumatic valve II is respectively connected to the liquid collecting tank III and the vacuum dryer in the gas-liquid separation and recovery device, and the vacuum dryer is respectively connected to the pneumatic valve II and the pneumatic valve III through pipelines.

[0020] Preferably, the powder collecting tank III is provided at the bottom end of the secondary filter in the gas-liquid separation and recovery device, the top end of the secondary filter is connected to the vacuum pump through a pipeline, the vacuum pump is connected to the gas storage component, the bottom end of the gas storage component is connected with the liquid collecting tank I, the gas storage component is connected to the dry cooling cryogenic refrigerator through a pipeline, the bottom end of the dry cooling cryogenic refrigerator is connected with the liquid collecting tank II, the dry cooling cryogenic refrigerator is connected to the refrigeration unit through the set circulating gas interface, the dry cooling cryogenic refrigerator is respectively connected to the powder collecting tank IV and the pneumatic valve III through pipelines, the bottom of the powder collecting tank IV is connected to the liquid collecting tank III; the pneumatic valve III is connected to the high-pressure pump through a pipeline, and the high-pressure pump is connected to the high-pressure gas storage gas.

[0021] Preferably, the high-pressure pump is a plunger pump, and the high-pressure gas storage is a gas cylinder.

[0022] Preferably, the feeding mechanism includes a hydraulic cylinder, a silo piston, a silo shell and a screw feeder. The hydraulic cylinder is connected to the top of the silo piston. The silo piston and the silo shell form a closed container chamber with a variable volume for accommodating the gel to be atomized. The screw feeder is arranged at the bottom of the silo shell, and a leakage hole is opened at the bottom of the silo shell. The gel to be atomized is atomized after passing through the leakage hole. The high-pressure atomizing spray disc is arranged at the bottom of the silo shell.

[0023] Step (5) is replaced by performing cyclic drying at intervals on the basis of vacuum drying, and the process of the cyclic drying is as follows: I, suction filtration and deliquescence, start the vacuum pump, so that the circuit is a negative pressure cycle, the liquid in the powder collecting tank IV settles to the bottom and flows into the liquid collecting tank III, so as to separate the powder and the liquid, and as the humidity of the powder decreases, the cycle continues to achieve the drying of the powder; II, remove the powder collecting tank IV after the suction filtration and deliquescence in step I and install it upside down on the vacuum dryer, pour the wet powder in the powder collecting tank IV into the vacuum dryer, start the dryer heating switch and the mixing motor, and continue to start the vacuum pump, so that the circuit is a negative pressure cycle; saturated steam is introduced into the vacuum dryer. After entering the dry cooling cryogenic freezer, heat exchange is carried out, and the evaporative substances therein are condensed, liquefied and precipitated, and the saturated steam becomes low-temperature unsaturated steam. It continues to flow backward and enters the vacuum dryer. The unsaturated steam is heated and the temperature increases as the solvent humidity that absorbs the wet powder increases. The gas changes from low-temperature saturated steam to high-temperature saturated steam; the high-temperature saturated steam is then discharged into the secondary filter, where the high-temperature saturated steam is filtered (powder-gas separation). The high-temperature saturated steam enters the dry cooling cryogenic freezer again for heat exchange, and the evaporative substances therein are condensed, liquefied and precipitated again, thereby continuously taking away the liquid volatiles inside the vacuum dryer to achieve cyclic drying of the powder.

[0024] Preferably, the preparation method of the silica sol in step (1) comprises the following steps: mixing silicon powder with a particle size of 50 to 600 mesh with deionized water and an alkaline solution, heating to 55 to 90° C., mechanically stirring, and then continuing to add silicon powder with a particle size of 50 to 600 mesh under mechanical stirring at 55 to 90° C., and then slowly adding the alkaline solution to obtain silica sol; the particle size of the obtained silica sol is 10 to 20 nm, wherein the mass ratio of the silicon powder and the alkaline solution added for the first time is (10 to 40):1, and the mass ratio of the silicon powder and the alkaline solution added for the second time is (8 to 35):1, and the deionized water is mixed in excess.

[0025] Preferably, the inert gas atomization in step (3) is specifically as follows: the pre-crushed gel is discharged into the atomization area of the spray disc through the leakage hole by the feeding mechanism, and at the same time, the high kinetic energy atomization medium (such as inert gas) is sprayed out through the spray disc provided in the atomization chamber, and the gel coming out of the leakage hole is instantly broken into tiny particles under the impact of the high-pressure jet. The tiny particles obtain kinetic energy due to the injection action, and then make discrete movements in the atomization chamber, and finally settle to the bottom cone of the atomization chamber at the bottom of the atomization chamber under the action of gravity, and finally the main body enters the powder collecting tank I.

[0026] Preferably, the alkaline solution is any one of sodium silicate, sodium hydroxide, potassium hydroxide, ammonia water, ethylamine, ethanolamine, dimethylamine, trimethylamine or tetrahydroxyammonium, or a mixture of at least two thereof.

[0027] Preferably, the silica sol is silica sol.

[0028] Preferably, the solubilizing diluent in step (1) and step (2) is a mixture of deionized water and alcohol, and the volume ratio of deionized water to alcohol is 1: (1 to 2.5).

[0029] Preferably, the modifier in step (1) is hexamethyldisilazane or a mixture of hexamethyldisilazane and hexamethyldisiloxane; wherein the weight ratio of hexamethyldisilazane to hexamethyldisiloxane in the mixture is 1:(0.5-1).

[0030] Preferably, the catalyst in step (2) and step (4) is one or a mixture of hydrochloric acid, sulfuric acid, nitric acid, acetic acid or phosphoric acid.

[0031] Preferably, the catalyst in step (2) and step (4) is acetic acid or phosphoric acid; and the alcohol is methanol or ethanol.

[0032] Preferably, the vacuum drying in step (5) is performed by negative pressure heating drying in a vacuum chamber, wherein the vacuum degree is 23.3 to 98.6 KPa; and an inert gas is introduced during the vacuum drying process.

[0033] Preferably, the inert gas is one of nitrogen and helium.

[0034] An aerogel powder is prepared by the above-mentioned preparation method, and the aerogel powder is SiO2 aerogel powder, and the specific surface area of the SiO2 aerogel powder is greater than 600m 2 / g, the thermal conductivity of the SiO2 aerogel powder is less than 0.015W / m·K, the contact angle of the SiO2 aerogel powder with water is greater than 120°C, and the particle size of the SiO2 aerogel powder is 10 to 35 μm.

[0035] An application of aerogel powder, wherein the aerogel powder is aerogel powder prepared by the above-mentioned preparation method, and the aerogel powder is SiO2 aerogel powder, and the application is used in one or more of the manufacturing processes of aerogel coating, aerogel insulation board, aerogel fiber or aerogel felt.

[0036] Post-hydrophobically modified wet gels and non-silica wet gels are also suitable for the atomization and drying preparation system of the present invention.

[0037] The technical effects of the present invention are:

[0038] (1) The present invention uses a hydrophobic modifier to perform surface hydrophobic modification on silica sol. At this time, the silica sol has completed cluster growth. The hydrophobic modifier directly modifies the surface of the cluster. By controlling the proportion of the catalyst, the Si-OH on the surface of the cluster is modified to Si-O-Si-CH3. Then, the catalyst is used to promote the cross-linking gel of the cluster (dehydration condensation reaction occurs between the residual Si-OH on the surface of the cluster) to obtain a hydrophobic SiO2 wet gel, thereby avoiding the defect that the hydrophobic groups are wrapped in the clusters during the hydrolysis process of the hydrophobic silicon source (such as MTMS, MTES), and the obtained SiO2 aerogel is not hydrophobic enough; on the basis of the specific modification, the present invention also uses a specific spray / mechanical granulation method. The steps directly obtain micron-sized SiO2 wet gel, avoiding the dust pollution and high energy consumption problems caused by the mechanical crushing of SiO2 aerogel; as a close coordination, the present invention directly uses alcohol as the solvent based on vacuum drying. Since the wet gel is a micron-sized powder, the path of alcohol drying and separation is greatly shortened, which can not only significantly shorten the drying time, but also greatly alleviate / solve the problem of SiO2 wet gel skeleton collapse caused by capillary force. The present invention obtains SiO2 aerogel powder through a normal pressure graded drying process, and the alcohol solvent obtained after evaporation can be reused. The above-mentioned overall multi-angle setting is coordinated and cooperated, which makes this technical route greatly shorten the production cycle and reduce material costs, and has huge market prospects.

[0039] (2) The atomization equipment of the present invention is crushed before gelation, which breaks through the existing conventional settings. In the preferred embodiment, the present invention realizes the recovery and treatment of the alcohol and gas used in the treatment process by specifically configuring the atomization and drying preparation system, so that the entire process basically does not emit waste gas and waste liquid, thereby greatly improving environmental friendliness. In particular, the connection and coordination relationship between the various components of the production process related to gas-liquid separation and recovery, and the components of the relevant steps such as powder dehydration and circulation drying are configured to enable rapid separation of powder and liquid, and achieve drying during the negative pressure circulation process, thereby improving the drying effect.

[0040] (3) In addition to setting specific parameters for each step such as hydrophobic modification, specific spraying / mechanical granulation, and alcohol atmospheric pressure drying, the present invention also sets specific parameters for each step, so that under the premise of the coordinated steps set by the present invention, the coordinated steps are promoted by the specific setting of parameters, so that the effect of each step is optimized. Through the coordination of the steps and the specific parameters of each step, the aerogel obtained is formed by the accumulation of nanoparticles and has a three-dimensional network structure, with a skeleton diameter of about 10nm and a pore size of less than 50nm; a thermal conductivity of about 0.013-0.016W / m·K, and a specific surface area of 600-1000m 2 / g, density is 0.05-0.15g / cm 3 , the average pore size is 20-30nm, and the contact angle is >120°. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a microscopic TEM image of SiO2 aerogel powder according to one embodiment of the present invention.

[0042] Figure 2 This is a schematic structural diagram of an atomizing drying treatment device according to one embodiment of the present invention.

[0043] Figure 3 It is a structural schematic diagram of the feeding mechanism and high-pressure atomizing spray disc of the present invention.

[0044] Figure 4 This is a simplified schematic diagram of the device configuration of the gas-liquid separation and recovery process according to one embodiment of the present invention.

[0045] Figure 5 This is a simplified schematic diagram of the device configuration of the cyclic drying process according to one embodiment of the present invention.

[0046] Figure 6 This is a simplified schematic diagram of the device configuration of the powder-liquid separation process according to one embodiment of the present invention.

[0047] in:

[0048] 1-feeding mechanism, 2-high-pressure atomizing spray disc, 3-atomizing chamber, 4-atomizing chamber bottom cone, 5-high-pressure centrifugal fan, 6-primary filter, 7-cyclone, 8-powder collecting tank I, 9-powder collecting tank II, 10-pneumatic valve I, 11-pneumatic valve II, 12-vacuum dryer, 13-secondary filter, 14-powder collecting tank III, 15-liquid collecting tank pressure relief interface, 16-vacuum pump, 17-gas storage component, 18-liquid collecting tank I, 19-dry cooling cryogenic freezer, 20-circulating gas interface, 21-refrigeration unit, 22-liquid collecting tank II, 23-powder collecting tank IV, 24-powder collecting tank bracket, 25-liquid collecting tank III, 26-pneumatic valve IV, 27-check valve, 28-water seal, 29-pneumatic valve III, 30-high-pressure pump, 31-high-pressure gas storage;

[0049] 101- hydraulic cylinder, 102- silo piston, 103- silo shell, 104- gel to be atomized, 105- screw feeder. DETAILED DESCRIPTION

[0050] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0051] The embodiments of the present invention all exemplarily use the following specific devices to perform specific processing:

[0052] like Figures 2 to 6 As shown, steps (3) to (5) of this embodiment use an atomization drying treatment device such as Figure 2 As shown, the atomization drying treatment device includes: a feeding mechanism, a high-pressure atomization spray disc, an atomization chamber, an atomization chamber bottom cone, a high-pressure centrifugal fan, a primary filter, a cyclone, a powder collecting tank I, a powder collecting tank II, a pneumatic valve I, a pneumatic valve II, a vacuum dryer, a gas-liquid separation and recovery device, a powder collecting tank IV, a liquid collecting tank III, an exhaust gas absorption component and a pneumatic valve III.

[0053] like Figure 2 As shown, the feeding mechanism is arranged at the top of the atomizing chamber, the high-pressure atomizing spray disc is arranged at the top of the atomizing chamber and located at the side bottom of the feeding mechanism, and the bottom cone of the atomizing chamber is located at the bottom of the atomizing chamber; the side of the atomizing chamber is connected to the tail gas absorption component and the high-pressure centrifugal fan through pipelines, the outlet end of the high-pressure centrifugal fan is connected to the pneumatic valve I and the primary filter respectively, the bottom end of the primary filter is connected to the powder collecting tank II, the bottom cone of the atomizing chamber is connected to the cyclone through a pipeline, and the cyclone is connected to the side of the primary filter and the powder collecting tank I respectively through pipelines; the pneumatic valve I is respectively connected to the secondary filter and the pneumatic valve II in the gas-liquid separation and recovery device, the pneumatic valve II is respectively connected to the liquid collecting tank III and the vacuum dryer in the gas-liquid separation and recovery device, and the vacuum dryer is respectively connected to the pneumatic valve II and the pneumatic valve III through pipelines.

[0054] The bottom end of the secondary filter in the gas-liquid separation and recovery device is provided with the powder collecting tank III, the top end of the secondary filter is connected to the vacuum pump through a pipeline, the vacuum pump is connected to the side of the gas storage component, the bottom end of the gas storage component is connected with the liquid collecting tank I, the side of the gas storage component is connected to the dry cooling cryogenic refrigerator through a pipeline, the bottom end of the dry cooling cryogenic refrigerator is connected with the liquid collecting tank II, the dry cooling cryogenic refrigerator is connected to the refrigeration unit through the provided circulating gas interface, the side of the dry cooling cryogenic refrigerator is respectively connected to the powder collecting tank IV and the pneumatic valve III through pipelines, the bottom of the powder collecting tank IV is connected to the liquid collecting tank III, the powder collecting tank IV is supported by a powder collecting tank bracket; the pneumatic valve III is connected to the plunger pump through a pipeline, and the plunger pump is connected to the gas storage bottle. As Figure 2 As shown, the gas storage component is a gas storage tank.

[0055] After atomization, the gel powder soaked in the alcohol solution and the alcohol solution are discharged into the cyclone through the bottom cone of the atomization chamber for preliminary solid-liquid separation. Part of the solid powder is collected in the powder collecting tank I, and the mixture is further discharged into the primary filter, where solid-liquid separation is further carried out. Part of the solid powder is collected in the powder collecting tank II. The liquid material is discharged into the secondary filter through the control of the pneumatic valve I, where solid-liquid separation is further carried out. Part of the solid powder is collected in the powder collecting tank III. Then, through the temperature gradient setting of the air storage component and the dry cooling cryogenic freezer, the solid powder is suction filtered and collected in the powder collecting tank IV.

[0056] During the operation of the equipment, due to the addition of atomizing medium and the fixed capacity of the atomizing chamber, overflow problems will inevitably occur, such as Figure 2 and 4 As shown, in this embodiment of the present invention, an overflow bypass is provided on the side of the atomizing chamber (at the inlet of the high-pressure centrifugal fan as shown in the figure), and the gas-liquid mixture exceeding the capacity of the atomizing chamber enters the gas-liquid separation and recovery device through the overflow bypass, and the gas-liquid separation and recovery device includes a secondary filter, a powder collecting tank III, a vacuum pump, a gas storage component, a liquid collecting tank I, a dry cooling cryogenic refrigerator, a refrigeration unit, a liquid collecting tank II, a plunger pump and a gas storage bottle; the gas-liquid mixture coming in from the overflow bypass is first purified by the secondary filter, and the powder is discharged into the powder collecting tank III, and the filtered gas-liquid mixture enters the gas storage component through the vacuum pump, and part of the liquid enters the liquid collecting tank under the action of gravity and temperature gradient. In tank I, the remaining gas-liquid mixture enters the heat exchange system consisting of a dry-cold cryogenic device and a refrigeration unit and carries out dry-cold and cryogenic treatment. The volatile matter of the saturated steam in the heat exchange system is condensed and converted into a liquid state by a vapor state. The liquid matter enters the liquid collecting tank II. During the whole process, due to the temperature gradient, each link has volatile matter that will condense, so a liquid collecting tank is provided. At the same time, cryogenic gas is obtained, and after the gas is pressurized by a plunger pump, it is filled into a gas cylinder. The cryogenic steam obtained by deep cooling is already very pure. The gas in the gas cylinder is entered into step (3) and reused. The liquid obtained in liquid collecting tank I and liquid collecting tank II is also purified and entered into step (3) and reused. The whole process is carried out in a closed and controlled environment, with almost no leakage and no emission, meeting environmental protection requirements. The plunger pump here can be carried out in conjunction with aerosolization, and the flow rate can match the gas consumption of the aerosolization process, allowing the atomization chamber to maintain a micro-negative pressure (not positive pressure).

[0057] like Figure 3As shown, the feeding mechanism includes a hydraulic cylinder, a silo piston, a silo shell and a screw feeder. The hydraulic cylinder is connected to the top of the silo piston. The silo piston is arranged in the silo shell. The silo shell is used to accommodate the gel to be atomized. The screw feeder is arranged at the bottom of the silo shell, and a leakage hole is opened at the bottom of the silo shell. The high-pressure atomizing spray disc is arranged at the bottom of the silo shell. Driven by the feed mechanism and piston pressure, the atomized gel overflows from the leak in the center of the spray disc. Simultaneously, high-pressure, high-kinetic-energy fluid (gas or liquid) is ejected from the high-pressure atomizing spray disc. When the overflowing gel comes into contact with the high-pressure, high-kinetic-energy fluid (gas or liquid), it is instantly shattered by the impact of the high-pressure atomizing spray disc jet, forming tiny particles. These particles gain a certain amount of kinetic energy and undergo discrete motion in the atomizing chamber. Ultimately, gravity settles to the bottom cone of the atomizing chamber, where they gradually enter powder collection tanks I (powder separated by the cyclone), II (powder separated by the primary filter), and III (powder produced by the secondary filter). Once the powder collection tanks are full (generally no more than 90% of their capacity), the gel is transferred to the next process.

[0058] When performing cycle drying, such as Figure 5 and Figure 6 As shown, the main process of circulating drying is divided into suction filtration and circulation drying. The operating conditions are that the pneumatic valve I (for gas and liquid recovery) is closed and the pneumatic valve II (for drying suction filtration) is open. Suction filtration and circulation drying can be carried out at the same time (controlled by valves), but it is not recommended to carry out them simultaneously with atomization. Figure 6 As shown, the liquid substance of the gel powder is directly extracted through negative pressure suction filtration. First, the powder collecting tank IV (suction filtration station) and the liquid collecting tank III (suction filtration station) are installed in place, and the loop valve is opened. Start the vacuum pump, and the loop negative pressure cycle is turned on. In the initial stage, the liquid content of the powder in the powder collecting tank IV (suction filtration station) is large, and the liquid will settle to the bottom (a bottom filter device can be provided) and flow into the liquid collecting tank III (suction filtration station). After the vacuum pump is started, the flow rate increases to achieve rapid separation of powder and liquid. In the later stage, the humidity of the powder decreases, and continuing the circulation also has the effect of drying the powder (the circulating gas becomes low-temperature unsaturated steam after passing through dry cold air), but the drying effect is reduced, and the tank needs to be changed. The powder tank after suction filtration enters the circulation drying process. As shown Figure 5As shown in the figure, in the circulating drying process, the filtered powder container is mounted on a vacuum dryer. The wet powder is poured into the dryer, the circuit valve is opened, the dryer's heating switch and mixing motor are activated, the vacuum pump is started, and the negative pressure circuit is activated. The air in the enclosed space is pumped by the vacuum pump. The saturated steam enters the dry cooler cryogenic freezer for heat exchange, condensing and liquefying the evaporated product. It then flows back to the vacuum dryer, where it is heated. As the solvent absorbing the wet powder increases in humidity, the steam transforms from low-temperature saturated steam to high-temperature saturated steam. After passing through the secondary filter, the steam undergoes another conversion from high-temperature saturated steam to low-temperature saturated steam, continuously removing liquid volatiles from the vacuum dryer, thus achieving a truly negative pressure cycle for the powder. In negative pressure drying, a true negative pressure is achieved by opening the exhaust gas bleed valve (the pneumatic valve III activated under atomization conditions, the plunger pump, and the gas cylinder) in the final stages of drying. This increases the vacuum level in the drying cycle, improving drying efficiency and results. The other is to fully carry out the circulation of saturated steam and unsaturated steam, and improve the drying effect by the number of cycles (time), and the latter will not be low in efficiency and will be economical.

[0059] The vacuum drying is carried out by negative pressure heating drying in a vacuum chamber, wherein the vacuum degree is 23.3-98.6 kPa (for example, it can be 25 kPa, 28 kPa, 31 kPa, 33 kPa, 36 kPa, 39 kPa, 42 kPa, 48 kPa, 53 kPa, 55 kPa, 59 kPa, 62 kPa, 68 kPa, 71 kPa, 75 kPa, 79 kPa, 82 kPa, 86 kPa, 89 kPa, 91 kPa, 95 kPa, 98 kPa), first at 40-70 ° C (for example, it can be 42 ° C, 45 ° C, 49 ° C, 51 ° C, 58 ° C, 60 ° C, 65 ° C, 69 ° C, etc.) vacuum drying for 1-2 h, and then at 100-120 ° C (for example, it can be 103 ° C, 108 ° C, 111 ° C, 115 ° C, 118 ° C) temperature conditions continue to vacuum dry for 1-2 h.

[0060] The heating temperature is 40-120° C. (for example, 42° C., 45° C., 49° C., 51° C., 58° C., 60° C., 65° C., 69° C., 75° C., 80° C., 85° C., 88° C., 91° C., 95° C., 98° C., 103° C., 108° C., 111° C., 115° C., or 118° C.); and an inert gas is introduced during the vacuum drying process. The inert gas may be nitrogen or helium.

[0061] like Figure 2 As shown, for the tail gas after passing through the atomization chamber, the tail gas is absorbed by the water seal and then discharged by setting the control of the pneumatic valve IV and the one-way valve.

[0062] Example 1

[0063] A method for preparing aerogel powder carried out in an aerogel factory in Hunan includes the following steps:

[0064] (1) Preparation of modified silica sol: silica sol, a dissolving agent and a modifier are uniformly mixed to obtain a modified silica sol, wherein the mass ratio of the silica sol, the dissolving agent and the modifier is 1:2.1:0.18. The dissolving agent is a mixture of deionized water and methanol in a volume ratio of 1:1.8; the modifier is a mixture of hexamethyldisilazane and hexamethyldisiloxane in a weight ratio of 1:0.8;

[0065] (2) Preparation of a coagulant solution: uniformly mixing a catalyst and a dissolving agent to obtain a coagulant solution; wherein the mass ratio of the catalyst to the dissolving agent is 1:2.5. The catalyst is phosphoric acid.

[0066] (3) Spray gel granulation, the modified silica sol obtained in step (1) and the coagulant obtained in step (2) are mixed evenly, and the gel treatment is carried out for 3.5 hours (in other embodiments, it can also be, for example, 20 minutes, 38 minutes, 55 minutes, 1.1 hours, 1.35 hours, 1.8 hours, 2.2 hours, 3.1 hours, 3.8 hours, 4.2 hours, 4.5 hours, 4.8 hours, 5.2 hours, 5.8 hours, etc.), and the obtained gel is pre-crushed into particles with a particle size of less than 3 mm, and then fed into the atomization chamber by a feeding mechanism, and a gel powder is obtained by atomization treatment. The particle size of the obtained gel powder is 1 to 50 microns (the average particle size can be 10 microns, 15 microns, 22 microns, 28 microns, 33 microns, 38 microns, 42 microns, 48 microns, etc.), an alcohol solution is filled at the bottom of the atomization chamber, and the gel powder falls into the alcohol solution at the bottom of the atomization chamber under the action of gravity, and the gel powder is immersed in the alcohol solution for solvent replacement; the atomization treatment is inert gas atomization, liquid atomization, vibration disk atomization or centrifugal atomization, and the temperature of the atomization treatment is 39°C (in other embodiments, it can also be, for example, 22°C, 28°C, 31°C, 33°C, 38°C, 41°C, 45°C, 49°C, etc.).

[0067] (4) pH adjustment: Add a catalyst to the alcohol solution soaked with the gel powder obtained in step (3) to adjust the pH value of the gel powder to 7. The pH adjustment soaking time is 3.1 h (in other embodiments, it can also be 2.2 h, 2.8 h, 3.8 h, 3.9 h, etc.).

[0068] (5) Vacuum drying: The gel powder soaked in the alcohol solution obtained in step (4) is vacuum dried as a whole, first vacuum dried at a temperature of 65°C for 1.5 hours, and then vacuum dried at a temperature of 110°C for 1.8 hours to obtain an aerogel powder product; at the same time, the alcohol solution obtained by drying is transferred to step (3) and reused as the alcohol solution in step (3).

[0069] (6) An overflow bypass is provided on the side of the atomizing chamber, and the gas-liquid mixture exceeding the capacity of the atomizing chamber enters the gas-liquid separation and recovery device through the overflow bypass, and the gas-liquid separation and recovery device comprises a secondary filter, a powder collecting tank III, a vacuum pump, a gas storage component, a liquid collecting tank I, a dry cooling cryogenic refrigerator, a refrigeration unit, a liquid collecting tank II, a plunger pump and a gas storage bottle; the gas-liquid mixture coming in from the overflow bypass is first purified by the secondary filter, and the powder is discharged into the powder collecting tank III, and the filtered gas-liquid mixture enters the gas storage component through the vacuum pump, and part of the liquid is discharged into the powder collecting tank III. Under the action of gravity and temperature gradient, the gas enters the liquid collecting tank I, and the remaining gas-liquid mixture enters the heat exchange system composed of a dry cooling cryogenic refrigerator and a refrigeration unit for dry cooling and cryogenic treatment. The volatile matter of the saturated steam in the heat exchange system is condensed and converted from vapor to liquid. The liquid enters the liquid collecting tank II, and low-temperature gas is obtained at the same time. The gas is pressurized by a plunger pump and then filled into a gas storage bottle. The gas in the gas storage bottle enters step (3) for reuse. The liquid obtained in the liquid collecting tank I and the liquid collecting tank II is also purified and then enters step (3) for reuse.

[0070] The microstructure of the obtained aerogel powder is as follows Figure 1 As shown, the performance parameters of the aerogel powder are shown in Table 1, which shows the performance indicators of the SiO2 aerogel powder obtained in Example 1.

[0071] Table 1

[0072]

[0073] From Table 1, it can be seen that the thermal conductivity, specific surface area, density, average pore size and contact angle of the SiO2 aerogel powder obtained in this embodiment of the present invention are all well balanced and excellent. Figure 1 It can be seen that aerogel is formed by the accumulation of nanoparticles and has a three-dimensional network structure. The diameter of the skeleton is about 10nm and the pore size is less than 50nm.

[0074] Example 2

[0075] This embodiment is a method for preparing the silica sol in Example 1, which specifically includes the following steps: I. Mixing silicon powder with a particle size of 50 to 600 mesh with deionized water and an alkaline solution, wherein the mass ratio of the silicon powder to the alkaline solution is 35:1, adding an excess of deionized water, heating to 69° C., and mechanically stirring; II. Then, continuing to add silicon powder with a particle size of 50 to 600 mesh under mechanical stirring at 69° C., and then slowly adding the alkaline solution, wherein the mass ratio of the silicon powder to the alkaline solution is 28:1, to obtain a silica sol (step II can be repeated in other embodiments); the particle size of the obtained silica sol is 10 to 20 nm.

[0076] Example 3

[0077] This embodiment is an example of circulating drying based on embodiment 1. The process of circulating drying is as follows: I. suction filtration and deliquoring, starting the vacuum pump to make the circuit a negative pressure circulation, the liquid in the powder collecting tank IV settles to the bottom and flows into the liquid collecting tank III, realizing the separation of the powder and the liquid, and as the moisture of the powder decreases, the circulation is continued to realize the drying of the powder; II. the powder collecting tank IV after the suction filtration and deliquoring in step I is removed and installed upside down on the vacuum dryer, the wet powder in the powder collecting tank IV is poured into the vacuum dryer, the heating switch and the mixing motor of the dryer are started, and the vacuum pump is continued to be started to make the circuit a negative pressure circulation; saturated After entering the dry cooling cryogenic refrigerator, the steam undergoes heat exchange, the evaporated matter condenses and liquefies, the saturated steam becomes low-temperature unsaturated steam, and continues to flow backward. The gas entering the vacuum dryer is heated and its temperature rises. As the humidity of the solvent that absorbs the wet powder increases, the gas changes from low-temperature unsaturated steam to high-temperature saturated steam; the high-temperature saturated steam is then discharged into the secondary filter, where it is converted into low-temperature saturated steam, and the low-temperature saturated steam enters the dry cooling cryogenic refrigerator again for heat exchange, thereby circulating the process to continuously take away the liquid volatiles inside the vacuum dryer, thereby achieving cyclic drying of the powder.

[0078] Comparative Example 1

[0079] In this comparative example, the vacuum drying step (5) in Example 1 is replaced by the conventional atmospheric drying process. The other settings are exactly the same as those in Example 1. By comparing the overall process and the aerogel finally obtained, it is found that the overall process of this comparative example not only extends the production cycle by 1.25 times compared with Example 1, but also performs a performance test on the obtained aerogel and finds that its specific surface area is 805m 2 / g, thus it can be proved that the various steps of the present invention are closely coordinated with each other, rather than producing their own effects separately, and the settings of the various steps of the present invention and the settings of the specific parameters are closely coordinated before and after.

[0080] The above-mentioned embodiments and comparative examples of the present invention are all examples and do not limit the scope of protection of the technical solution. The fact that there is no comparison of technical features does not mean that there are no outstanding substantial features, but only uses textual descriptions to illustrate the setting method. The above-mentioned embodiments are preferred implementation methods of the present invention, but the implementation methods of the present invention are not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A device for preparing aerogel powder, characterized in that: The preparation device is an atomization drying treatment device, comprising: a feeding mechanism (1), a high-pressure atomization spray disc (2), an atomization chamber (3), an atomization chamber bottom cone (4), a high-pressure centrifugal fan (5), a primary filter (6), a cyclone (7), a powder collecting tank I (8), a powder collecting tank II (9), a pneumatic valve I (10), a pneumatic valve II (11), a vacuum dryer (12), a gas-liquid separation and recovery device, a powder collecting tank IV (23), a liquid collecting tank III (25), an exhaust gas absorption component and a pneumatic valve III (29); The feeding mechanism (1) is arranged at the top of the atomizing chamber (3), the high-pressure atomizing spray disc (2) is placed at the top of the atomizing chamber (3) and at the bottom of the feeding mechanism (1), and the bottom cone (4) of the atomizing chamber is located at the bottom of the atomizing chamber (3); the atomizing chamber (3) is connected to the tail gas absorption component and the high-pressure centrifugal fan (5) through pipelines, the outlet end of the high-pressure centrifugal fan (5) is connected to the pneumatic valve I (10) and the primary filter (6) respectively, the bottom end of the primary filter (6) is connected to the powder collecting tank II (9), and the bottom cone (4) of the atomizing chamber is connected to the exhaust gas absorption component and the high-pressure centrifugal fan (5) through pipelines. The cyclone (7) is connected to the side of the primary filter (6) and the powder collecting tank I (8) through pipelines; the pneumatic valve I (10) is connected to the secondary filter (13) and the pneumatic valve II (11) in the gas-liquid separation and recovery device, respectively; the pneumatic valve II (11) is connected to the liquid collecting tank III (25) and the vacuum dryer (12) in the gas-liquid separation and recovery device, respectively; the vacuum dryer (12) is connected to the pneumatic valve II (11) and the pneumatic valve III (29) through pipelines; The gas-liquid separation and recovery device comprises a secondary filter (13), a powder collecting tank III (14), a vacuum pump (16), a gas storage component (17), a liquid collecting tank I (18), a dry cooling cryogenic device (19), a refrigeration unit (21), a liquid collecting tank II (22), a high-pressure pump (30) and a high-pressure gas storage (31); the bottom end of the secondary filter (13) in the gas-liquid separation and recovery device is provided with a powder collecting tank III (14), the top end of the secondary filter (13) is connected to the vacuum pump (16) through a pipeline, the vacuum pump (16) is connected to the gas storage component (17), and the bottom end of the gas storage component (17) is connected to the liquid collecting tank. I (18), the gas storage component (17) is connected to the dry cooling cryogenic refrigerator (19) through a pipeline, the bottom end of the dry cooling cryogenic refrigerator (19) is connected to the liquid collecting tank II (22), the dry cooling cryogenic refrigerator (19) is connected to the refrigeration unit (21) through the provided circulating gas interface (20), the dry cooling cryogenic refrigerator (19) is connected to the powder collecting tank IV (23) and the pneumatic valve III (29) through pipelines, respectively, the bottom of the powder collecting tank IV (23) is connected to the liquid collecting tank III (25); the pneumatic valve III (29) is connected to the high-pressure pump (30) through a pipeline, and the high-pressure pump (30) is connected to the high-pressure gas storage (31); The feeding mechanism (1) comprises a hydraulic cylinder (101), a silo piston (102), a silo shell (103) and a screw feeder (105). The hydraulic cylinder (101) is connected to the top of the silo piston (102). The silo piston (102) and the silo shell (103) form a closed container chamber with a variable volume for accommodating the gel to be atomized. The screw feeder (105) is arranged at the bottom of the silo shell, and a leakage hole is opened at the bottom of the silo shell. The gel to be atomized is atomized after passing through the leakage hole. The high-pressure atomizing spray disc (2) is arranged at the bottom of the silo shell (103).

2. A method for preparing aerogel powder, characterized in that: The steps include: (1) preparing a modified silica sol, mixing silica sol, a dissolving agent and a modifier to obtain a modified silica sol, wherein the mass ratio of the silica sol, the dissolving agent and the modifier is 1: (1-3.5): (0.05-0.3); (2) Preparation of a coagulant solution, mixing the catalyst and the dissolving diluent uniformly to obtain a coagulant solution; wherein the mass ratio of the catalyst to the dissolving diluent is 1:(1-20); (3) spray gel granulation, the modified silica sol obtained in step (1) and the coagulant obtained in step (2) are mixed evenly, and after gel treatment for 15 minutes to 6 hours, the obtained gel is pre-crushed into particles with a particle size of less than 3 mm, and then fed into the atomization chamber by a feeding mechanism, and a gel powder is obtained by atomization treatment, and the particle size of the obtained gel powder is 1 to 50 microns. An alcohol solution is filled at the bottom of the atomization chamber, and the gel powder falls into the alcohol solution at the bottom of the atomization chamber under the action of gravity, and the gel powder is immersed in the alcohol solution for solvent replacement; the atomization treatment is inert gas atomization, and the temperature of the atomization treatment is 20 to 50 ° C; (4) Vacuum drying: the gel powder soaked in the alcohol solution is separated from the alcohol solution by solid-liquid separation, and then the solid matter is vacuum dried, first vacuum dried at a temperature of 40-70°C for 1-2 hours, and then vacuum dried at a temperature of 100-120°C for 1-2 hours to obtain an aerogel powder product; at the same time, the alcohol solution obtained by drying is transferred to step (3) and reused as the alcohol solution for purification in step (3); (5) An overflow bypass is provided in the atomization chamber, and the gas-liquid mixture exceeding the capacity of the atomization chamber enters the gas-liquid separation and recovery device through the overflow bypass, and the gas-liquid separation and recovery device comprises a secondary filter, a powder collecting tank III, a vacuum pump, a gas storage component, a liquid collecting tank I, a dry cooling cryogenic refrigerator, a refrigeration unit, a liquid collecting tank II, a high-pressure pump and a high-pressure gas storage; the gas-liquid mixture coming in from the overflow bypass is first purified by the secondary filter, leaving the powder in the powder collecting tank III, and the filtered gas-liquid mixture enters the gas storage component through the vacuum pump, and part of the liquid enters the liquid collecting tank I under the action of gravity and temperature gradient. The remaining gas-liquid mixture enters a heat exchange system consisting of a dry cooling cryogenic refrigerator and a refrigeration unit for dry cooling and cryogenic treatment. In the heat exchange system, the saturated steam is condensed, and the volatile matter therein is converted from a vapor state to a liquid state and enters the liquid collecting tank II. At the same time, relatively pure low-temperature gas is obtained. The gas is pressurized by a high-pressure pump and then filled into a high-pressure gas storage. The gas in the high-pressure gas storage enters step (3) for reuse or does not enter step (3). The liquid obtained in the liquid collecting tank I and the liquid collecting tank II enters step (3) for reuse or does not enter step (3) after purification. Steps (3) to (5) are carried out using the aerogel powder preparation device according to claim 1.

3. The method for preparing aerogel powder according to claim 2, characterized in that: After step (3) and before step (4), there is also step (3'): (3') pH adjustment: adding a catalyst to the alcohol solution soaked with the gel powder obtained in step (3) to adjust the pH value of the gel powder to 6.8-7.

2. The pH adjustment soaking time is 2-4 hours.

4. The method for preparing aerogel powder according to claim 2, wherein: Step (5) is replaced by performing cyclic drying at intervals on the basis of vacuum drying. The main process of the cyclic drying is divided into suction filtration and dehydration and cyclic drying. The operating conditions are that the pneumatic valve I is closed and the pneumatic valve II is opened. Specifically: I, suction filtration and dehydration, start the vacuum pump to make the circuit a negative pressure cycle, the liquid in the powder collecting tank IV settles to the bottom and flows into the liquid collecting tank III, to achieve separation of powder and liquid, as the moisture of the powder decreases, continue the cycle to achieve drying of the powder; II, remove the powder collecting tank IV after suction filtration and dehydration in step I and install it upside down on the vacuum dryer, pour the wet powder in the powder collecting tank IV into the vacuum dryer, start the dryer heating switch and mixing motor, and continue Start the vacuum pump to make the circuit a negative pressure cycle; after entering the dry cooling cryogenic refrigerator, the saturated steam undergoes heat exchange, the evaporated matter condenses, liquefies and precipitates, and the saturated steam becomes low-temperature unsaturated steam, which continues to flow backward. After entering the vacuum dryer, the gas is heated and the temperature rises. As the humidity of the solvent that absorbs the wet powder increases, the gas changes from low-temperature unsaturated steam to high-temperature saturated steam; the high-temperature saturated steam is then discharged into the secondary filter, where it is filtered to achieve powder-gas separation. The high-temperature saturated steam enters the dry cooling cryogenic refrigerator again for heat exchange, where the evaporated matter condenses, liquefies and precipitates again, thereby continuously taking away the volatile matter inside the vacuum dryer to achieve cyclic drying of the powder.

5. The method for preparing aerogel powder according to claim 2, wherein: The preparation method of the silica sol in step (1) comprises the following steps: mixing silicon powder with a particle size of 50-600 mesh with deionized water and an alkaline solution, heating to 55-90° C., mechanically stirring, and then continuing to add silicon powder with a particle size of 50-600 mesh under the condition of mechanical stirring at 55-90° C., and then slowly adding the alkaline solution to obtain silica sol; the particle size of the obtained silica sol is 10-20 nm, wherein the mass ratio of the silicon powder and the alkaline solution added for the first time is (10-40):1, and the mass ratio of the silicon powder and the alkaline solution added for the second time is (8-35):1, and the deionized water is mixed in excess.

6. The method for preparing aerogel powder according to claim 2, wherein: The inert gas atomization in step (3) is specifically as follows: the pre-crushed gel is discharged into the atomization area of the high-pressure atomizing spray disc through the leakage hole by the feeding mechanism, and at the same time, the high-pressure atomizing spray disc sprays the high-kinetic energy atomizing medium. The gel coming out of the leakage hole is instantly broken into tiny particles under the impact of the high-pressure jet. The tiny particles obtain kinetic energy due to the injection action, and then make discrete movements in the atomizing chamber. Under the action of gravity, they settle into the bottom cone of the atomizing chamber at the bottom of the atomizing chamber, and the main body enters the powder collecting tank I.

7. The method for preparing aerogel powder according to claim 3, characterized in that: The silica sol is silica sol; The dissolution aid diluent in step (1) and step (2) is a mixture of deionized water and alcohol, and the volume ratio of deionized water to alcohol is 1: (1-2.5); The modifier in step (1) is hexamethyldisilazane or a mixture of hexamethyldisilazane and hexamethyldisiloxane; wherein the weight ratio of hexamethyldisilazane to hexamethyldisiloxane in the mixture is 1:(0.5~1); The catalyst in step (2) and step (3') is one or a mixture of hydrochloric acid, sulfuric acid, nitric acid, acetic acid or phosphoric acid; In step (4), the temperature is increased by heat conduction heating or microwave heating.

8. The method for preparing aerogel powder according to claim 2, wherein the high-pressure pump is a plunger pump, and the high-pressure gas storage is a gas cylinder.

9. The method for preparing aerogel powder according to claim 5, characterized in that: The alkaline solution is any one of sodium silicate, sodium hydroxide, potassium hydroxide, ammonia water, ethylamine, ethanolamine, dimethylamine, trimethylamine or tetrahydroxyammonium, or a mixture of at least two of them.

10. The method for preparing aerogel powder according to claim 6, characterized in that: The catalyst in step (2) and step (4) is acetic acid or phosphoric acid; the alcohol is methanol or ethanol.

11. The method for preparing aerogel powder according to claim 2, characterized in that: The vacuum drying in step (4) is performed by negative pressure heating drying in a vacuum chamber, wherein the vacuum degree is 23.3 to 98.6 kPa; and an inert gas is introduced during the vacuum drying process.

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