An on-line purification method of supercritical alcohol aerogel solvent

Abstract

The application discloses an online purification method of alcohol supercritical aerogel solvent. The application fully utilizes the heat energy carried by the alcohol supercritical fluid (250 DEG C-270 DEG C, 10 MPa-13 MPa) itself, realizes the process separation and purification purpose on line, reduces the equipment investment cost, reduces the production process link, reduces the production management cost, improves the solvent turnover use efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of aerogel composite thermal insulation materials, and particularly relates to an online purification method for an alcohol supercritical aerogel solvent. Background Art

[0002] In the industrial production of aerogel composite insulation materials, the recycling and reuse of organic solvents is an unavoidable process link. The solvent extracted by supercritical extraction has a complex composition, containing the impregnation agent on the surface of the substrate fiber, nano-silica particles, salt ions after catalyst neutralization, unreacted modifiers, a small amount of ammonia water, etc. If it is not purified by the process and reused in the production of aerogel composite insulation materials, the harmful impurities introduced into the material will have different contents in each batch, and there will be no consistency in the product composition. As the number of solvent reuses increases, the harmful impurities accumulate in the product. The reuse of unpurified solvents will also cause instability in the sol-gel process, resulting in unstable product performance and a decrease in yield. Therefore, unpurified supercritical alcohol solvents cannot be directly reused in the process.

[0003] Commonly used solvent purification solutions in the industry include distillation, vacuum distillation, rectification, etc., which require large equipment investments. Regardless of the purification process solution adopted, a dedicated process link must be set up, dedicated equipment layout site, dedicated personnel to manage the purification section, additional energy input, and high process costs. Summary of the Invention

[0004] To address the high energy consumption and investment associated with independent purification processes in existing technologies, the present invention provides an online purification method for alcohol supercritical aerogel solvents. This method is an alcohol supercritical aerogel-assisted production process and also an online solvent purification method. Through a unique process flow design, the present invention fully utilizes the inherent thermal energy of the alcohol supercritical fluid (250°C-270°C, 10MPa-13MPa) to achieve online separation and purification, reducing equipment investment costs, simplifying production process steps, lowering production management costs, and improving solvent turnover efficiency.

[0005] The technical solutions of the present invention are as follows:

[0006] The online purification method of an alcohol supercritical aerogel solvent disclosed in the present invention achieves the purpose of purifying the solvent by utilizing the heat energy carried by the supercritical alcohol fluid itself by adding a gas-liquid separation tank and a bottom liquid purification tank to the alcohol supercritical pipeline, thereby achieving economic investment, energy saving, high purification efficiency, and simple equipment management.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] An online purification method for an alcohol supercritical aerogel solvent comprises the following steps:

[0009] S1. Construction of an online purification system for alcohol supercritical aerogel solvent: including an alcohol supercritical device, a gas-liquid separation tank, a bottom liquid purification tank, a water-cooled heat exchanger, an alcohol receiving tank, pipelines, and pipeline valves; the volume ratio of the alcohol supercritical device, gas-liquid separation tank, and bottom liquid purification tank that constitute the system is 1:(0.15-0.3):(0.05-0.12); the pipeline valves include a high-pressure pressure control valve;

[0010] The alcohol supercritical equipment, the gas-liquid separation tank, the bottom liquid purification tank, the water-cooled heat exchanger and the alcohol receiving tank are connected in sequence through pipelines, wherein the gas-liquid separation tank is a single-layer tank, the bottom liquid purification tank is a jacketed tank, a high-pressure pressure-controlling valve is provided on the pipeline between the alcohol supercritical equipment and the gas-liquid separation tank, a nitrogen filling branch is provided on the pipeline after the high-pressure pressure-controlling valve, and a nitrogen valve is provided to control the on-off of nitrogen;

[0011] The pressure difference between the pressure before and after the high-pressure pressure-control valve is large. The temperature of the alcohol supercritical fluid before the high-pressure pressure-control valve is 250°C~270°C and the pressure is 10MPa~13MPa, and the temperature after the valve is 110°C~120°C and the pressure is ≤1MPa.

[0012] The high pressure control valve has a diameter change of 1: (5-8) times before and after;

[0013] All pipes and valves in contact with the alcohol solvent are made of 316L stainless steel;

[0014] S2. Nitrogen purge: Before the alcohol supercritical equipment reaches the supercritical drying condition, open the nitrogen valve in advance, introduce nitrogen, purge the entire pipeline equipment system, replace the oxygen in the system, and close the nitrogen valve after the nitrogen replacement operation is completed;

[0015] S3. Supercritical fluid pressure relief: Open the high-pressure pressure control valve, and the alcohol supercritical fluid (temperature 250℃~270℃, pressure 10MPa~13MPa) enters the gas-liquid separation tank from the middle and lower part of the gas-liquid separation tank through the pipeline. The gas phase enters the jacket of the bottom liquid purification tank from the upper pipeline of the gas-liquid separation tank; the high-boiling point liquid phase, solid amorphous silicon oxide particles, short fibers and a small amount of salt ions remain at the bottom of the gas-liquid separation tank;

[0016] S4, bottom liquid purification: The bottom liquid of the gas-liquid separation tank generated in the previous supercritical drying cycle is pumped into the bottom liquid purification tank in advance. The 110°C~120°C alcohol vapor enters the jacket of the bottom liquid purification tank from the upper pipe of the gas-liquid separation tank, transfers part of the heat to the bottom liquid in the bottom liquid purification tank, and then flows out from the lower interface of the jacket, condenses, and enters the alcohol receiving tank; in the bottom liquid purification tank, the alcohol solvent in the bottom liquid is heated to the boiling point, flows out from the pipe at the upper part of the bottom liquid purification tank, condenses, and enters the alcohol receiving tank;

[0017] S5. The high-boiling-point organic matter and impurities at the bottom of the bottom liquid purification tank are discharged from the bottom liquid purification tank drain port, and the bottom liquid at the bottom of the gas-liquid separation tank is pumped into the bottom liquid purification tank in advance for purification in the next drying cycle;

[0018] S6. The purified alcohol solvent received in the ethanol receiving tank is pumped to the sol-gel process for reuse.

[0019] Furthermore, the volume ratio of the alcohol supercritical equipment, gas-liquid separation tank, and bottom liquid purification tank described in S1 is 1:(0.15~0.3):(0.05~0.12). For example, if the volume of the supercritical equipment is 1000L, the volume of the corresponding gas-liquid separation tank is 150L~300L, and the volume of the bottom liquid purification tank is 50L~120L.

[0020] The gas-liquid separation tank is vertical and tall, with a height / diameter ratio of 1:(0.25~0.4). For example, if the height of the gas-liquid separation tank is 1800mm, the corresponding tank diameter is 450mm~720mm. The working state of the gas-liquid separation tank is that the supercritical fluid enters from the lower part of the gas-liquid separation tank. Under normal working conditions, the liquid is sealed in the bottom liquid, and the high-temperature alcohol vapor is exposed to the liquid bottom liquid. The heat energy is transferred to the liquid phase, and the low-boiling point alcohol is evaporated by heat. The high-boiling point fiber wetting agent, particulate matter and salt ions are retained in the bottom liquid of the gas-liquid separation tank.

[0021] There is a 1:(5~8) times diameter change before and after the high-pressure pressure-control valve. For example, the diameter of the pipeline before the valve corresponding to a supercritical equipment with a volume of 1000L is 15mm@300℃, 20MPa. After passing through the high-pressure pressure-control valve, the diameter of the corresponding pipeline becomes 75mm@200℃~120mm@200℃, 2MPa.

[0022] Furthermore, the discharge flow rates in S3 before and after supercriticality vary greatly. After gas-liquid equilibrium, the internal pressure of the gas-liquid separation tank is 0.3MPa~0.7MPa, and the temperature is 110℃~120℃; after the completion of a supercritical process, the ratio of the bottom liquid remaining at the bottom of the tank and the purified gas-phase alcohol solvent is equal to 1:7.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The online purification method for an alcohol supercritical aerogel solvent disclosed herein utilizes the heat energy carried by the supercritical alcohol fluid to purify and separate the solvent. High-boiling-point wetting agent and solid impurities remain at the bottom of the gas-liquid separator tank, while alcohol vapor flows out through a pipe at the top of the tank for condensation and collection. The condensed alcohol solvent purified in the separator tank is colorless and transparent. During the purification process, 0.1% by weight of wetting agent and 0.05% to 0.1% by weight of solid impurities, such as nano-silica particles and salt ions, remain in the liquid phase of the separator tank. A 1m³ supercritical drying system can produce 800L (approximately 636kg) of alcohol supercritical fluid after a single supercritical process. During the purification process, approximately 0.636kg of wetting agent and 0.318kg to 0.636kg of solid impurities remain in the liquid phase of the separator tank.

[0025] 2. In the online purification method of an alcohol supercritical aerogel solvent described in the present invention, the heat energy carried by the alcohol supercritical fluid itself, which was originally used for forced water circulation cooling and wasted heat energy, is now used for self-purification without the need for additional heat energy input, thereby reducing energy consumption.

[0026] According to the existing production practice of aerogel materials, a 1100L supercritical drying equipment consumes about 810kWh of electricity to complete a complete supercritical drying process, including heating the organic sol ethanol in the material to 260℃, 12MPa; after reaching the process conditions, the supercritical fluid at 260℃, 12MPa is passed into the cooling coil to cool and collect (waste ethanol to be distilled). The whole process energy consumption; completing a supercritical process, it can dry out 0.8m³ aerogel composite material and 800L (about 636kg) of alcohol supercritical fluid. This part of the alcohol supercritical fluid cannot be directly reused in the process because it contains fiber sizing agent, nano-silica particles, fibers and salt ions, and needs to be purified. The power consumption of purifying 1kg of ethanol by offline distillation is about 0.36kwh. The 636kg of alcohol solvent condensed from the first supercritical condensation is purified by offline distillation, which consumes 229kwh. After completing the supercritical drying process and the solvent ethanol in the process reaches the state where it can be reused in the process, the comprehensive energy consumption is 810kwh + 229kwh = 1039kwh.

[0027] In the online purification method of an alcohol supercritical aerogel solvent of the present invention, the energy consumption of a 1100L supercritical drying equipment to complete a complete supercritical drying process is also 810kwh. The difference is that after the supercritical fluid passes through the high-pressure pressure-controlling valve V1, the volume expands rapidly (absorbs heat) in the gas-liquid separation tank, the pressure drops to below 1MPa, and the temperature drops to 110℃~120℃. The low-boiling-point alcohol vapor escapes from the upper pipeline of the tank body and enters the jacket of the bottom liquid purification tank, and is condensed and collected after heat exchange; the high-boiling-point wetting agent and other impurities remain in the liquid phase at the bottom of the tank; the high-temperature supercritical fluid is continuously introduced after passing through the high-pressure pressure-controlling valve V1, and fully exchanges heat with the liquid phase at the bottom of the tank in the gas-liquid separation tank to cause the low-boiling-point alcohol solvent in the liquid phase to escape, and the high-boiling-point wetting agent, impurities and a small amount of alcohol vapor are liquefied into the liquid phase, forming a dynamic equilibrium gas-liquid two-phase in the gas-liquid separation tank until the supercritical drying process is completed.

[0028] This method fully utilizes the substantial thermal energy of supercritical alcohol fluid (260°C, 12 MPa) to achieve online separation and purification. Solvent purification is simultaneously completed simultaneously with supercritical drying. Using this online purification process, a single 1100L supercritical drying unit consumes only 810 kWh of energy per cycle. The ethanol collected in the ethanol receiving tank can be directly reused in the process. In summary, while achieving the same ethanol reuse goal, the online purification process saves 229 kWh of energy, a 22.04% energy saving rate of 229 / 1039 x 100%.

[0029] 3. The online purification method of an alcohol supercritical aerogel solvent described in the present invention greatly improves process efficiency and reduces the amount of process circulating solvent used. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0031] Figure 1 This is a process flow chart of an online purification method of an alcohol supercritical aerogel solvent according to the present invention;

[0032] Figure 2 The figure is a process flow chart of the existing online purification method of alcohol supercritical aerogel solvent.

[0033] Description of the numbers in the figure:

[0034] T, temperature instrument; P, pressure instrument; M, stirring motor; V1, high-pressure pressure controlling valve; V2, bottom liquid purification tank feed valve; V3, ethanol receiving tank discharge valve; V4, nitrogen valve. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] Example 1:

[0037] An online purification method for alcohol supercritical aerogel solvent, such as Figure 1 , including the following steps:

[0038] S1. Construction of an online purification system for alcohol supercritical aerogel solvent: This system consists of an alcohol supercritical device (i.e., an ethanol supercritical drying kettle), a gas-liquid separation tank, a bottom liquid purification tank, a water-cooled heat exchanger, an ethanol receiving tank, pipelines, and pipeline valves. The volume ratio of the alcohol supercritical device, gas-liquid separation tank, and bottom liquid purification tank is 1:0.15:0.12. The pipeline valves include a high-pressure pressure control valve V1.

[0039] The ethanol supercritical equipment, gas-liquid separation tank, bottom liquid purification tank, water-cooled heat exchanger and ethanol receiving tank are connected in sequence through pipelines. A high-pressure pressure-control valve V1 is provided on the pipeline between the ethanol supercritical equipment and the gas-liquid separation tank. A nitrogen filling branch is provided on the pipeline after the high-pressure pressure-control valve V1, and a nitrogen valve V4 is provided to control the on-off of nitrogen.

[0040] The pressure difference between the pressure before and after the high-pressure pressure-controlling valve V1 is large. The temperature of the alcohol supercritical fluid before the high-pressure pressure-controlling valve V1 is 260°C and the pressure is 12MPa, while the temperature after the valve is 110°C and the pressure is ≤1MPa.

[0041] The high-pressure control valve V1 has a diameter change of 1:5 before and after;

[0042] All pipes and valves in contact with the alcohol solvent are made of 316L stainless steel;

[0043] S2. Nitrogen purge: Before the alcohol supercritical equipment reaches the supercritical drying condition, open the nitrogen valve V4 in advance, introduce nitrogen, purge the entire pipeline equipment system, and replace the oxygen in the system. After the nitrogen replacement operation is completed, close the nitrogen valve V4;

[0044] S3, supercritical fluid pressure relief: Open the pressure control valve V1, and the alcohol supercritical fluid (temperature 260℃, pressure 12MPa) enters the gas-liquid separation tank from the middle and lower part of the gas-liquid separation tank through the pipeline. The gas phase enters the jacket of the bottom liquid purification tank from the upper pipeline of the gas-liquid separation tank; the high-boiling point liquid phase, solid amorphous silicon oxide particles, short fibers and a small amount of salt ions remain at the bottom of the gas-liquid separation tank;

[0045] S4, bottom liquid purification: 1 / 8 of the bottom liquid of the gas-liquid separation tank generated in the previous supercritical drying cycle is pumped into the bottom liquid purification tank in advance, and the 110°C~120°C ethanol vapor enters the jacket of the bottom liquid purification tank from the upper pipe of the gas-liquid separation tank, transfers part of the heat to the bottom liquid in the bottom liquid purification tank, and then flows out from the lower interface of the jacket of the dripping purification tank, enters the ethanol receiving tank after condensation; in the bottom liquid purification tank, the ethanol in the bottom liquid is heated to the boiling point, flows out from the pipe on the upper part of the bottom liquid purification tank, and enters the ethanol receiving tank after condensation;

[0046] S5. The high-boiling-point organic matter and impurities at the bottom of the bottom liquid purification tank are discharged from the bottom liquid purification tank drain port, and the bottom liquid at the bottom of the gas-liquid separation tank is pumped into the bottom liquid purification tank in advance for purification in the next drying cycle;

[0047] S6. The purified ethanol received in the ethanol receiving tank is pumped to the sol-gel process for reuse.

[0048] Example 2:

[0049] An online purification method for an alcohol supercritical aerogel solvent comprises the following steps:

[0050] S1. Construction of an online purification system for alcohol supercritical aerogel solvent: This system consists of an alcohol supercritical device (i.e., an ethanol supercritical drying kettle), a gas-liquid separation tank, a bottom liquid purification tank, a water-cooled heat exchanger, an ethanol receiving tank, pipelines, and pipeline valves. The volume ratio of the alcohol supercritical device, gas-liquid separation tank, and bottom liquid purification tank is 1:0.3:0.05. The pipeline valves include a high-pressure pressure control valve V1.

[0051] The ethanol supercritical equipment, gas-liquid separation tank, bottom liquid purification tank, water-cooled heat exchanger and ethanol receiving tank are connected in sequence through pipelines. A high-pressure pressure-control valve V1 is provided on the pipeline between the ethanol supercritical equipment and the gas-liquid separation tank. A nitrogen filling branch is provided on the pipeline after the high-pressure pressure-control valve V1, and a nitrogen valve V4 is provided to control the on-off of nitrogen.

[0052] The pressure difference between the pressure before and after the high-pressure pressure-controlling valve V1 is large. The temperature of the alcohol supercritical fluid before the high-pressure pressure-controlling valve V1 is 260°C and the pressure is 12MPa, while the temperature after the valve is 110°C and the pressure is ≤1MPa.

[0053] The high-pressure control valve V1 has a diameter change of 1:8 before and after;

[0054] All pipes and valves in contact with the alcohol solvent are made of 316L stainless steel;

[0055] S2, nitrogen purging: before the alcohol supercritical device reaches the complete supercritical drying conditions, open the nitrogen valve V4 in advance, and introduce nitrogen to purge the entire pipeline equipment system, and replace the oxygen in the system. After the nitrogen replacement operation is completed, close the nitrogen valve V4;

[0056] S3, supercritical fluid pressure relief: open the pressure control valve V1, and alcohol supercritical fluid (temperature 260℃, pressure 12MPa) enters the gas-liquid separation tank from the lower part of the gas-liquid separation tank through the pipeline, and the gas phase part enters the jacket of the bottom liquid purification tank from the upper pipeline of the gas-liquid separation tank; the high-boiling-point liquid phase, solid amorphous silicon particles, short fibers and a small amount of salt ions remain at the bottom of the gas-liquid separation tank;

[0057] S4, bottom liquid purification: 1 / 8 of the bottom liquid of the gas-liquid separation tank generated in the last supercritical drying cycle is pumped into the bottom liquid purification tank in advance, and the 110℃-120℃ ethanol vapor entering the bottom liquid purification tank jacket from the upper pipeline of the gas-liquid separation tank gives part of the heat to the bottom liquid in the bottom liquid purification tank, and then flows out from the lower interface of the bottom liquid purification tank jacket, and after condensation, enters the ethanol receiving tank; in the bottom liquid purification tank, the ethanol in the bottom liquid is heated to boiling point and flows out from the upper pipeline of the bottom liquid purification tank, and after condensation, enters the ethanol receiving tank;

[0058] S5, the high-boiling-point organic matter and impurities at the bottom of the bottom liquid purification tank are discharged from the bottom liquid purification tank blowdown port, and the bottom liquid at the bottom of the gas-liquid separation tank is pumped into the bottom liquid purification tank for purification in the next drying cycle;

[0059] S6, the purified ethanol received in the ethanol receiving tank is pumped to the sol-gel process for reuse.

[0060] Comparative example:

[0061] The process of the online purification method of the alcohol supercritical aerogel solvent is as shown in Figure 2

[0062] After the supercritical alcohol fluid passes through the high-pressure pressure relief valve, forced cooling heat exchange of the condenser is performed, and the solvent alcohol solvent and the infiltrant on the surface of the base material fiber, the nano silicon dioxide particles, the salt ions after neutralization of the catalyst, the unreacted modifier, and a small amount of ammonia water are all mixed together and cannot be directly used in the process. After purification by a special offline purification equipment, it can be used in production.

[0063] Results and discussion:

[0064] By comparing the examples and the comparative example, compared with the prior art, the beneficial effects brought by the online solvent purification method of the application are:

[0065] A. The heat energy carried by the supercritical alcohol fluid itself is used to realize the purification and separation of the solvent; the high-boiling-point infiltrant and solid impurities remain at the bottom of the separation tank, and the alcohol vapor flows out from the tank top pipeline and is collected after condensation;​

[0066] B. The heat energy carried by the alcohol supercritical fluid, which was originally used for forced water circulation cooling and wasted, is now used for self-purification; no additional heat energy input is required, thus reducing energy consumption;

[0067] The purification method of the present invention directly uses process heat for self-purification, without the need for additional heat input. For example, in an actual electric heating distillation process, it is statistically estimated that the distillation of 500 kg of 95% ethanol consumes approximately 180 kWh of electricity. The unit energy consumption for distilling 1 kg of 95% alcohol is approximately 0.36 kWh / kg. A 1 m³ supercritical drying equipment can complete a single supercritical process to produce 0.8 m³ of aerogel composite material and 800 L (approximately 636 kg) of alcohol supercritical fluid. The corresponding fluid is completely distilled using an offline process scheme, consuming approximately 229 kWh of electricity. Based on an industrial electricity consumption of 0.7 yuan / kWh, the distillation cost is approximately 160.3 yuan, and the cubic meter distillation cost is approximately 200.375 yuan.

[0068] Table 1: Taking a production line with an annual production capacity of 10,000 m³ as an example:

[0069]

[0070] As shown in the above comparison, the purification method of the present invention directly saves 2,003,750 RMB per year in energy costs compared to electric distillation, and 1,001,875 RMB per year compared to natural gas distillation. It also reduces equipment investment costs, eliminating the need for electric and gas-fired thermal oil boilers.

[0071] C. Online separation and purification: when the supercritical process is completed, the solvent purification is also completed, which greatly improves the process efficiency and reduces the amount of process circulating solvent used;

[0072] Compared with the offline purification process, the online purification method of the present invention condenses the supercritical solvent and collects it in a tank. After accumulating to a certain amount, it is pumped out for purification. The improvement in the purification efficiency of the solvent is obvious. For example, a 1.1m³ supercritical device will dry out about 800L of supercritical fluid in one supercritical drying. Using the online drying method of the present invention, the 800L fluid will complete the ethanol purification at the same time as the supercriticality is completed; according to the offline solvent purification method, it is necessary to wait until the supercriticality is completed before the condensed supercritical fluid to be purified is pumped into the bottom liquid purification tank to start purification. Even if it is pumped into the bottom liquid purification tank in batches in advance for purification, there is always a batch of fluid to be purified that has not been pumped when the supercriticality is completed. Therefore, the efficiency of the solvent purification process is always higher than that of offline purification.

[0073] Specifically, taking a 1m³ device as an example, completing one supercritical process can dry out 0.8m³ aerogel composite material and 800L (about 636kg) of alcohol supercritical fluid;

[0074] Table 2: Comparison of online solvent recycling usage

[0075]

[0076] In summary, the online purification system of the present invention has better purification immediacy and the highest solvent recovery efficiency, which reduces the process recycling amount by 20% compared with high-power purification equipment. If offline purification is selected, the solvent recycling amount is increased by 1 time.

[0077] D. No need to purchase complete sets of purification equipment, reducing equipment investment;

[0078] E. No dedicated process site is required to achieve the purification purpose. It can be dispersed under the supercritical operating platform, and no dedicated management personnel are required;

[0079] The online purification method of the present invention achieves the purpose of purifying the solvent by utilizing the heat energy carried by the supercritical alcohol fluid itself by adding a gas-liquid separation tank and a bottom liquid purification tank to the alcohol supercritical pipeline, thereby achieving economic investment, energy saving, high purification efficiency and simple equipment management.

Claims

1. An online purification method for alcohol supercritical aerogel solvent, characterized by: The following steps are involved: S1. Construction of an online purification system for alcohol supercritical aerogel solvent: This system consists of an alcohol supercritical device, a gas-liquid separation tank, a bottom liquid purification tank, a water-cooled heat exchanger, an alcohol receiving tank, pipelines, and pipeline valves. The volume ratio of the alcohol supercritical device, gas-liquid separation tank, and bottom liquid purification tank is 1:(0.15-0.3):(0.05-0.12). The pipeline valves include a high-pressure pressure control valve (V1). The alcohol supercritical equipment, the gas-liquid separation tank, the bottom liquid purification tank, the water-cooled heat exchanger and the alcohol receiving tank are connected in sequence by pipelines, wherein the gas-liquid separation tank is a single-layer tank and the bottom liquid purification tank is a jacketed tank. A high-pressure pressure-controlling valve (V1) is provided on the pipeline between the alcohol supercritical equipment and the gas-liquid separation tank. A nitrogen filling branch is provided on the pipeline after the high-pressure pressure-controlling valve (V1), and a nitrogen valve (V4) for controlling the on-off of nitrogen is provided on the nitrogen filling branch. The pressure difference between the pressure before and after the high-pressure pressure-controlling valve (V1) is large. The pressure before the high-pressure pressure-controlling valve (V1) is alcohol supercritical fluid with a temperature of 250°C to 270°C and a pressure of 10MPa to 13MPa, while the temperature after the valve is 110°C to 120°C and the pressure is ≤1MPa. The high-pressure pressure control valve (V1) has a diameter change of 1: (5-8) times before and after; All pipes and valves in contact with the alcohol solvent are made of 316L stainless steel; S2, nitrogen purge: before the alcohol supercritical equipment reaches the supercritical drying condition, open the nitrogen valve (V4) in advance, introduce nitrogen, purge the entire pipeline equipment system, replace the oxygen in the system, and close the nitrogen valve (V4) after the nitrogen replacement operation is completed; S3, supercritical fluid pressure relief: open the high-pressure pressure control valve (V1), the alcohol supercritical fluid enters the gas-liquid separation tank from the middle and lower part of the gas-liquid separation tank through the pipeline, and the gas phase enters the jacket of the bottom liquid purification tank from the upper pipeline of the gas-liquid separation tank; the high-boiling point liquid phase, solid amorphous silicon oxide particles, short fibers and a small amount of salt ions remain at the bottom of the gas-liquid separation tank; S4, bottom liquid purification: The bottom liquid of the gas-liquid separation tank generated in the previous supercritical drying cycle is pumped into the bottom liquid purification tank in advance. The 110°C~120°C alcohol vapor enters the jacket of the bottom liquid purification tank from the upper pipe of the gas-liquid separation tank, transfers part of the heat to the bottom liquid in the bottom liquid purification tank, and then flows out from the lower interface of the jacket, condenses, and enters the alcohol receiving tank; in the bottom liquid purification tank, the alcohol in the bottom liquid is heated to the boiling point, flows out from the pipe at the upper part of the bottom liquid purification tank, condenses, and enters the alcohol receiving tank; S5. The high-boiling-point organic matter and impurities at the bottom of the bottom liquid purification tank are discharged from the sewage outlet, and the bottom liquid at the bottom of the gas-liquid separation tank is pumped into the bottom liquid purification tank in advance for purification in the next drying cycle; S6. The purified alcohol solvent received in the alcohol receiving tank is pumped to the sol-gel process for reuse.

2. The online purification method of an alcohol supercritical aerogel solvent according to claim 1, characterized in that: The volume ratio of the alcohol supercritical equipment, gas-liquid separation tank, and bottom liquid purification tank constituting the system described in S1 is 1:(0.15~0.3):(0.05~0.12), wherein the volume of the alcohol supercritical equipment is 1000L, and the corresponding volume of the gas-liquid separation tank is 150L~300L, and the volume of the bottom liquid purification tank is 50L~120L.

3. The online purification method of an alcohol supercritical aerogel solvent according to claim 1, characterized in that: The gas-liquid separation tank constituting the system described in S1 is vertical, tall and thin, with a height / diameter ratio of 1:(0.25~0.4), a gas-liquid separation tank height of 1800mm, and a corresponding tank diameter of 450mm~720mm.

4. The online purification method of an alcohol supercritical aerogel solvent according to claim 1, characterized in that: The high-pressure pressure-controlling valve (V1) of the system described in S1 has a diameter change of 1:(5~8) times before and after. Specifically, the diameter of the pipeline before the valve corresponding to the 1000L alcohol supercritical equipment is 15mm@300℃, 20MPa. After passing through the high-pressure pressure-controlling valve (V1), the diameter of the corresponding pipeline becomes 75mm@200℃~120mm@200℃, 2MPa.

5. The online purification method of an alcohol supercritical aerogel solvent according to claim 1, characterized in that: The supercritical fluid in S3 is depressurized and after gas-liquid equilibrium is achieved, the internal pressure of the gas-liquid separation tank is 0.3MPa~0.7MPa and the temperature is 110℃~120℃; after the primary supercritical process is completed, the ratio of the bottom liquid remaining at the bottom of the tank to the purified gaseous alcohol solvent is equal to 1:7.

Images