Efficient cleaning process of supercritical extraction equipment

Abstract

The invention provides an efficient cleaning process of supercritical extraction equipment. The efficient cleaning process comprises the following steps: S1, a separation system; s2, cleaning an extraction system; s3, cleaning a separation system; s4, cleaning a tail gas recovery system; and S5, cleaning the whole system. According to the efficient cleaning technology of the supercritical extraction equipment, the cleaning efficiency of the extraction equipment can be greatly improved, the best cleaning effect is achieved, meanwhile, the equipment cleaning steps and the needed time are reduced, and the situation that the equipment is damaged due to disassembly and assembly in the cleaning process and the sealing performance of the equipment is affected is avoided; meanwhile, the problem that equipment is seriously corroded due to the fact that a large number of cleaning machines are used in the cleaning process is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of supercritical extraction equipment operation, and particularly relates to a high-efficiency cleaning process for supercritical extraction equipment. BACKGROUND

[0002] The supercritical extraction equipment is an extraction equipment integrating extraction and separation functions in a supercritical state. Since supercritical extraction is performed by using a supercritical fluid, the density of the supercritical fluid is similar to that of a liquid, but the viscosity is close to that of a gas, which is an ideal extraction process. In recent years, the supercritical extraction equipment has been increasingly mature in the extraction of green plant oil, and the industrialization development has been increasingly rapid. However, after the supercritical extraction is completed, plant oil remains in the equipment, and the equipment needs to be cleaned before being used for the next extraction. The cleaning of the extraction equipment has great difficulty. First, the extraction equipment is a closed space to a large extent, the pipeline is long and has corners, the equipment is large, the structure is complex and irregular, for example, the heating device is composed of multiple coils or tubes, and the cleaning is very difficult. In the existing related literature, the extraction equipment needs to be disassembled, and each part needs to be cleaned separately, or a high-concentration cleaning agent needs to be added to the equipment to improve the cleaning effect. The above methods not only take time and effort, but also shorten the service life of the equipment pipeline, valves and instruments. Therefore, a process method capable of reducing the cleaning cost of the supercritical extraction equipment needs to be found. SUMMARY

[0003] To solve the above problems, the application provides a high-efficiency cleaning process for supercritical extraction equipment, which divides the extraction equipment into an extraction system, a separation system and a tail gas recovery system, and separately cleans the three parts, and provides a cleaning process and a cleaning agent for each part to improve the cleaning effect and the cleaning efficiency.

[0004] A high-efficiency cleaning process for supercritical extraction equipment, specifically comprising the following steps: S1: Separation system, adjusting the extraction system, the separation system and the tail gas recovery system of the supercritical extraction equipment to an independent state. After the operation of the extraction equipment, the pollution degrees of the three parts are different. The extraction cleaning system is slightly polluted, the separation system is heavily polluted, and the tail gas recovery system is slightly polluted. The pipeline environment of the extraction system, the separation system and the tail gas recovery system is disconnected, and each part is independently cleaned, which can reduce the mutual pollution between the parts and reduce the cleaning difficulty.

[0005] S2: Cleaning the extraction system. The extraction system is only slightly contaminated, so cleaning is relatively simple. The first cleaning cycle uses alkaline water, followed by a second cleaning cycle using clean water. The extraction system generally includes a circulating water pump, an extraction heater, an extraction vessel, and connecting pipes. The circulating water pump allows the liquid to circulate between the extraction heater and the extraction vessel through the connecting pipes.

[0006] First, pump a 1% to 5% concentration of alkaline water into the extraction system from the top of the extraction vessel, ensuring that the temperature of the alkaline water is controlled at 50 to 80°C. Then, start the circulating water pump to allow the alkaline water to circulate and clean inside the extraction system for 10 to 20 minutes. After the circulation and cleaning are completed, open the drain valve of the extraction vessel and carry out circulation cleaning and draining work at the same time until no dirt is discharged from the drain port.

[0007] The second step involves pumping clean water into the extraction system after the alkaline water cleaning is completed, and then circulating and cleaning the system for 10 to 20 minutes. After cleaning, the drain valve of the extraction vessel is opened, and the circulation cleaning and draining work is carried out simultaneously until no dirt is discharged from the drain port.

[0008] After dissolving and removing the residual vegetable oil in the extraction system with alkaline water, the extraction system is then washed with clean water to ensure that no organic matter remains in the extraction system.

[0009] S3: Cleaning and Separation System. The separation system includes a circulating water pump, a separation heater, a separation vessel, and connecting pipes. The circulating water pump allows the liquid to circulate between the separation heater and the separation vessel through the connecting pipes. Due to the heavy contamination of the separation system, and the fact that most separation systems include two separation vessels, making the structure more complex, a deep five-stage cleaning process is required. The first stage uses compressed air purging, the second stage uses carbon dioxide circulation cleaning, the third stage uses alkaline water circulation cleaning, the fourth stage uses surfactant circulation cleaning, and the fifth stage uses alcohol circulation cleaning.

[0010] The first step involves introducing compressed air into the separation system, opening the drain port at the bottom of the separation vessel, and using compressed air to expel any remaining contaminants from the drain port until no more contaminants are discharged. Using compressed air to remove most of the attached contaminants effectively improves subsequent cleaning efficiency and reduces the amount of cleaning agents needed.

[0011] The second step involves carbon dioxide extraction and cleaning. Carbon dioxide is introduced into the separation vessel, and the flow rate is adjusted to 100-1000 kg / h. The cleaning is continuously circulated for 0.5-1 hour. Then, the drain port of the separation vessel is opened, and the carbon dioxide is kept in balance at the set parameters until no dirt is discharged.

[0012] If the separation system contains two separation vessels, this process will involve targeted cleaning based on their location. For the first separation vessel with higher contamination levels, the cleaning pressure will be set to 7–16 MPa and the temperature to 40–50°C. For the second separation vessel with lower contamination levels, the cleaning pressure will be set to 3–5 MPa and the temperature to 50–60°C. This allows for cleaning with a smaller amount of carbon dioxide.

[0013] The third step involves preparing an alkaline solution with a concentration of 1%–5% and a temperature of 50–80°C. This solution is then pumped into the separation system and continuously circulated for 10–60 minutes. After this, circulation is stopped, and the system is soaked for 0.5–1 hour until the contaminants are fully dissolved. The circulating water pump is then started again for 0.1–1 hour of continuous cleaning. The drain outlet is then opened, and the system is simultaneously circulated and the contaminants are discharged from the separation system. This process continues until no more contaminants are discharged.

[0014] The fourth step involves preparing the surfactant, pumping it into the separation system, and controlling the circulating water pump to start the circulation cleaning for 10 to 20 minutes. Then, open the drain outlet and continue the circulation cleaning while simultaneously draining the waste, allowing the waste to be discharged along with the surfactant, until no more waste is discharged.

[0015] The activator is a 50%–60% alcohol solution containing polyglycerol fatty acid esters, wherein the polyglycerol fatty acid esters account for 4%–8% by mass.

[0016] Preferably, the concentration of the surfactant alcohol solution in this step is 50%–60%, and the mass ratio of polyglycerol fatty acid ester is 6%–8%. Since there is a significant amount of residual contaminants in the separation system, prolonged cleaning with strong alkaline water is not feasible. Therefore, a surfactant formulated with polyglycerol fatty acid ester is used to enhance cleaning, achieving an oil removal rate of over 99%.

[0017] Fifth, add 10-50L of alcohol to the separation vessel, turn on the circulating water pump for circulation cleaning, then open the drain port and continue circulation cleaning and draining, using alcohol to remove the last remaining dirt until no dirt is discharged.

[0018] S4: Cleaning the exhaust gas recovery system. The exhaust gas recovery system includes a circulating water pump, filter, precooler, intermediate storage tank, and connecting pipelines. The circulating water pump allows for circulation between the filter, precooler, and intermediate storage tank via the connecting pipelines. Because the exhaust gas recovery system has a lower pollution level than the separation system but a higher pollution level than the extraction system, and its equipment complexity is higher than that of the extraction system, a three-stage cleaning process is employed. The first stage uses alkaline water for circulating cleaning, the second stage uses an active agent for circulating cleaning, and the third stage uses alcohol for circulating cleaning.

[0019] The first step involves preparing an alkaline solution with a concentration of 1%–5% and a temperature of 50–80°C. The alkaline solution is then pumped into the exhaust gas recovery system. The circulating water pump is turned on for 10–30 minutes of circulation cleaning. After that, the soaking is stopped for 0.5–1 hour, and the circulating water pump is restarted for 0.1–0.5 hours. Then, the drain outlet is opened, and the waste is discharged while the system is circulating and cleaning, allowing the waste to be discharged along with the alkaline solution. The process continues until no more waste is discharged.

[0020] The second step involves preparing the active solvent. In this step, the concentration of the active solvent in the alcohol solution is 50%–60%, and the mass ratio of polyglycerol fatty acid ester is 4%–5%. The active agent is pumped into the exhaust gas recovery system, and the circulating water pump is turned on for 10–20 minutes for circulation cleaning. Then, the drain outlet is opened, and the waste is discharged while the circulation cleaning is being carried out, allowing the waste to be discharged along with the active agent, until no waste is discharged and then the process is stopped.

[0021] The third step involves adding 10-50L of alcohol to the exhaust gas recovery system filter, turning on the circulating water pump for cleaning, opening the drain port, and simultaneously cleaning and draining the wastewater using the alcohol to remove any remaining contaminants until no more waste is discharged.

[0022] In steps S3 and S4, when performing alcohol circulation cleaning, flowing clean water can be added at the same time as alcohol is added. The clean water is pumped into the separation vessel to mix with the alcohol for cleaning. The flow rate of the circulating water pump is adjusted to 10-20 L / h, so that the alcohol forms an alcohol solvent with a continuously decreasing concentration gradient as clean water is gradually added, which improves the dissolution and cleaning effect of dirt. After the circulating water pump has been running for 10-20 minutes, the drain port is opened, and the sludge is discharged while the circulation cleaning is being carried out until no dirt is discharged, thus completing the alcohol circulation cleaning.

[0023] Preferably, sodium hydroxide solution is used in all the above steps to achieve the best cleaning effect while avoiding the corrosive effect of residue on the extraction equipment.

[0024] S5: Clean the entire system, adjust the extraction system, separation system and exhaust gas recovery system to the connected state, and use carbon dioxide for no-load circulation cleaning. By circulating carbon dioxide inside the entire extraction equipment, the cleanliness of the equipment is further improved, while maintaining the internal environment and pressure.

[0025] First, vent the carbon dioxide recovered from the previous extraction into the intermediate storage tank. Then, replenish with new carbon dioxide, start the equipment, and adjust it to the start-up state for no-load carbon dioxide circulation cleaning. Set the extraction pressure to 20-30 MPa, extraction temperature to 40-50℃, separation pressure to 6-10 MPa, extraction flow rate to 1500-2500 kg / h, and cleaning time to 0.5-1 hour until no impurities are discharged from the outlet of the separation vessel. Then, stop the machine and shut down the system, and close all inlets and outlets to maintain pressure. Before the next use of the equipment, open the valves to vent the internal carbon dioxide, and it can be used directly. The pressure-maintaining operation allows the internal space of the equipment to be filled with carbon dioxide, isolating oxygen, preventing internal bacterial growth, and extending the cleaning effect.

[0026] On the other hand, since the extraction system, separation system and exhaust gas recovery system have been separated in step S1, they will not affect each other. Therefore, steps S2, S3 and S4 can be carried out simultaneously, which greatly improves cleaning efficiency and reduces the overall cleaning time.

[0027] The high-efficiency cleaning process for supercritical extraction equipment provided by this invention can significantly improve the cleaning efficiency of the extraction equipment. While achieving the best cleaning effect, it reduces the number of cleaning steps and the time required, avoids damage caused by disassembling and assembling the equipment during the cleaning process, and avoids affecting the sealing performance of the equipment. At the same time, it solves the problem of maintaining the internal environment of the equipment after cleaning and avoids the problem of bacterial growth during equipment shutdown. Detailed Implementation

[0028] To further illustrate the concept of this invention, specific embodiments will be provided below for detailed explanation. These embodiments are merely illustrative and explanatory and should not be construed as limiting the scope of protection of this invention. All technologies implemented based on the content of this invention are covered within the scope of protection intended by this invention. Example 1

[0029] Adjust the supercritical extraction equipment that has extracted oil to a state where the extraction system, separation system, and exhaust gas recovery system are cleaned, so that the extraction system, separation system, and exhaust gas recovery system form separate functional zones.

[0030] Cleaning the extraction system: Prepare a 2% sodium hydroxide solution at 50℃ and set aside. Start the extraction circulating water pump and pump the sodium hydroxide solution into the extraction system. After 15 minutes of alkaline water circulation cleaning, drain the wastewater. Then pump in clean water for another 15 minutes of circulation cleaning. After draining the wastewater, the cleaning of the extraction system is complete.

[0031] Cleaning and Separation System: Step 1: Use compressed air to purge and blow out contaminants by opening the drain port. Step 2: Pressurize the first and second separation vessels using a pressure pump to the set parameters: first separation vessel pressure 7MPa, separation temperature 50℃; second separation vessel pressure 4MPa, separation temperature 60℃. Set the flow rate to 300kg / h and the cleaning time to 0.5h for carbon dioxide extraction cleaning. After the cleaning time, open the drain port of the separation vessel until no contaminants are discharged. Step 3: Add a 60℃, 3% sodium hydroxide alkaline solution for circulating cleaning. The circulating water pump should be running for 20 minutes, followed by soaking for 0.5h. After soaking, start the circulating water pump again for 0.2h of continuous cleaning. Then, while continuing the cleaning cycle, open the drain valve of the separation system to discharge contaminants. Step 4: Prepare a 60% alcohol solution and add 8% polyglycerol fatty acid ester. Connect this solution to the circulating water pump and pump this surfactant solution into the separation system. The circulating water pump should be running for 15 minutes and then stopped. Afterward, while continuing the cleaning cycle, open the drain valve of the separation vessel to discharge contaminants until no contaminants are discharged. The fifth step is to open the separator lid and add 50L of alcohol. Then, connect the treated water to the circulation pump and pump the water into the separator to mix with the alcohol for cleaning. Adjust the flow rate of the circulation pump to 10L / h so that the alcohol forms a certain concentration gradient as the water gradually enters, which can better clean the residual pigments in the separation system. The circulation pump is turned on for 20 minutes. After that, while circulating and cleaning, open the drain valve of the separator to drain the waste until no waste is discharged.

[0032] Cleaning the exhaust gas recovery system: First, add 50℃, 2% alkaline water for circulating cleaning, and run the circulating water pump for 20 minutes. Then soak for 0.5 hours. After soaking, start the circulating water pump again for 0.2 hours of circulating cleaning. Then, while circulating cleaning, open the drain valve of the exhaust gas recovery system to drain the sewage. The second step involves preparing a 50% alcohol solution, adding 4% polyglycerol fatty acid ester, and connecting it to a water circulation pump. This solution is then pumped into the exhaust gas recovery system. The circulation pump runs for 15 minutes and then stops. While the system is circulating and cleaning, the exhaust gas recovery system's drain valve is opened to drain the wastewater until no more waste is discharged. After the surfactant cleaning is complete, the filter inlet is opened, and 50L of alcohol is added. Clean water is then connected to the circulation pump, which pumps the clean water into the filter to mix with the alcohol for cleaning. The circulation pump flow rate is adjusted to 5L / h, allowing the alcohol to gradually enter and form a concentration gradient, thus better cleaning the residual pigments in the exhaust gas recovery system. The circulation pump runs for 20 minutes, and while the system is circulating and cleaning, the exhaust gas recovery system's drain valve is opened to drain the wastewater until no more waste is discharged.

[0033] Carbon dioxide gas no-load circulation cleaning of the entire system: After all three subsystems have been cleaned, adjust the overall system to the connected state, vent the carbon dioxide gas recovered from the previous extraction to the intermediate storage tank, replenish with new carbon dioxide gas, and adjust the equipment to the start-up state for carbon dioxide gas no-load circulation cleaning. The cleaning process is as follows: extraction pressure 20MPa, extraction temperature 40℃, separation pressure 6MPa, separation temperature 40℃, extraction flow rate 1500kg / h, cleaning time 0.5h, using carbon dioxide for no-load circulation cleaning. Continue until no impurities are discharged from the separation vessel, then stop the machine, close the system inlet and outlet valves, and maintain pressure.

[0034] Comparative Example 1 Remove the flange connected to the separator heater on the supercritical fluid extraction equipment that has extracted the oil. Inject 5% hot alkaline solution into each pipe until it overflows, then reinstall the flange. The alkaline solution temperature is 50℃, the hot water temperature in the separator heater jacket is 50℃, and the soaking time is 1 hour. After soaking, remove both flanges and rinse with a high-pressure water gun. Then, blow away the accumulated liquid in the tubes with compressed air before reinstalling the flange and setting it aside for later use. Next, clean the separator. First, disconnect the gas valve connecting the intermediate storage tank and the extraction vessel to the separator. Open the valve connecting the separator to the extract to release carbon dioxide gas. Open the lid and pour in 5% hot alkaline solution until it reaches one-third of the separator's volume. The alkaline solution temperature is 50℃, the hot water temperature in the separator jacket is 50℃, and the soaking time is 1 hour. After soaking, rinse thoroughly with a high-pressure water gun and blow away with compressed air until all wastewater is discharged. Set it aside for later use. Next, the carbon dioxide gas in the equipment is purged and replenished with new carbon dioxide. The carbon dioxide in the closed gas lines of the extraction vessels, pipelines, intermediate storage tanks, and other equipment is purged. After purging the carbon dioxide from the intermediate storage tank, new carbon dioxide is replenished and it is ready for use. Then, the alkaline water series circulation cleaning begins. After the intermediate storage tank is filled with new carbon dioxide, equal amounts of alkaline solution are poured into each of the three extraction vessels. The vessel lids are closed, and the equipment is adjusted to the start-up state. The equipment is adjusted to operate in a 1-2-3 series configuration until all three vessels have been cleaned simultaneously in series. Then, it is adjusted to a 3-1 series configuration for cleaning, and so on, to complete the cleaning of all extraction pipelines. The alkaline water cleaning process is as follows: extraction pressure 20MPa, extraction temperature 50℃, separation pressure 8MPa, separation temperature 50℃, extraction flow rate 1500kg / h, alkaline water concentration 5%, alkaline water volume 80L, and cleaning time 2 hours. After the alkaline water circulation cleaning is completed, all outlets are opened to remove carbon dioxide from the system. Then, the intermediate storage tank is refilled with new carbon dioxide and ready for use. Next, a series of clean water circulation cleaning begins. 100L of clean water is poured into each of the three extraction vessels, the lids are closed, and the equipment is switched on. The equipment is initially set to a 1-in-2-in-3 configuration for cleaning. After all three vessels have been cleaned simultaneously in series, the configuration is switched to a 3-in-1 configuration, and so on, until all extraction pipelines are cleaned. The clean water cleaning process is as follows: clean water volume: 100L, extraction pressure: 20MPa, extraction temperature: 50℃, separation pressure: 6MPa, separation temperature: 50℃, extraction flow rate: 1500kg / h, cleaning time: 2h, until the pH reaches 7-8, then set aside. Finally, after the cleaning water circulation is complete, all drain pipes are opened to drain the clean water until no water flows out. The equipment is then switched on, and carbon dioxide is used for no-load circulation cleaning. During the pressurization process, the drain valves are open to allow the carbon dioxide to carry away the water. After 2-3 minutes, all drain valves are closed, and circulation begins.The cleaning process is as follows: extraction pressure 20MPa, extraction temperature 50℃, separation pressure 6MPa, separation temperature 50℃, extraction flow rate 1500kg / h, cleaning time 2h, until no impurities are discharged from the separation vessel, then stop the machine, close the inlet and outlet valves of the system to maintain pressure until the next use of the equipment, then open the drain valve again to drain the sewage. After the sewage is drained, the equipment can be used directly.

[0035] The cleaning process and effects of Example 1 and Comparative Example 1 are statistically analyzed in the table below:

[0036] Experimental results show that the cleaning process employed in this invention significantly improves the cleaning efficiency of supercritical extraction equipment, reducing cleaning time to less than 15% of existing processes and halving the required manpower, thus effectively increasing production efficiency and reducing production costs. Furthermore, the significantly reduced cleaning difficulty eliminates the need for disassembling and reassembling valves and pipes during the cleaning process, greatly improving the tightness of equipment connections. In subsequent supercritical extraction operations, the probability of air leakage is reduced to 20%–50% of the original level, effectively improving the quality of processed products. Deep cleaning of the supercritical extraction equipment prevents residual grease from corroding the internal components, extending the equipment's service life and reducing operating costs.

[0037] There are many methods and approaches that can realize the technical solution of this invention, and the above are merely preferred embodiments provided by way of example. Those skilled in the art can conceive of many modifications, alterations, and substitutions without departing from this invention. It should be understood that various alternatives to the embodiments of this invention described herein can be employed in the practice of this invention. The appended claims are intended to define the scope of this invention and therefore cover the methods within the scope of these claims and their equivalents. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

Claims

1. A highly efficient cleaning process for supercritical fluid extraction equipment, characterized in that, Includes the following steps: S1: Separation system, which adjusts the extraction system, separation system and exhaust gas recovery system to independent states; S2: Cleaning the extraction system, using alkaline water for the first cycle of cleaning, and clean water for the second cycle of cleaning; S3: The cleaning and separation system uses compressed air for the first cleaning, carbon dioxide for the second circulating cleaning, alkaline water for the third circulating cleaning, surfactant for the fourth circulating cleaning, and alcohol for the fifth circulating cleaning. S4: Clean the exhaust gas recovery system, using alkaline water for the first cycle cleaning, activator for the second cycle cleaning, and alcohol for the third cycle cleaning. S5: Clean the entire system, adjust the extraction system, separation system and tail gas recovery system to the connected state, and use carbon dioxide for no-load circulation cleaning.

2. The high-efficiency cleaning process for the supercritical extraction equipment according to claim 1, characterized in that: The activator is a 50%–60% alcohol solution containing polyglycerol fatty acid esters, wherein the polyglycerol fatty acid esters account for 4%–8% by mass.

3. The high-efficiency cleaning process for the supercritical extraction equipment according to claim 2, characterized in that: The alkaline solution is sodium hydroxide solution.

4. The high-efficiency cleaning process for the supercritical extraction equipment according to claim 3, characterized in that: In step S2, the first step is to pump 1% to 5% alkaline water from the top of the extraction vessel. The temperature of the alkaline water is 50 to 80°C. The alkaline water is circulated in the extraction system for 10 to 20 minutes by a circulating water pump. Then the drain port of the extraction vessel is opened, and the circulation cleaning and drainage are carried out simultaneously until no dirt is discharged. The second step involves pumping clean water into the extraction system after the alkaline water cleaning is completed, circulating the clean water for 10-20 minutes. Then, the drain port of the extraction vessel is opened, and the system is simultaneously circulated for cleaning and draining until no more contaminants are discharged.

5. The high-efficiency cleaning process for the supercritical extraction equipment according to claim 3, characterized in that: In step S3, the first step is to introduce compressed air into the separation system and open the drain port at the bottom of the separation vessel until no dirt is discharged from the drain port. The second step involves carbon dioxide extraction and cleaning. The carbon dioxide flow rate is set to 100-1000 kg / h, and the cleaning time is 0.5-1 hour. Then, the drain port of the separation vessel is opened, and the carbon dioxide is kept in balance at the set parameters until no dirt is discharged. The third step involves pumping alkaline water with a concentration of 1% to 5% and a temperature of 50 to 80°C into the separation system, circulating it for 10 to 60 minutes, then soaking for 0.5 to 1 hour, then starting the circulating water pump to circulate and clean for 0.1 to 1 hour, and then opening the drain outlet to simultaneously circulate and clean and discharge the wastewater until no waste is discharged. The fourth step involves preparing a 50%–60% alcohol solution, then adding 6%–8% polyglycerol fatty acid ester to obtain an activator. The activator is then pumped into the separation system. After the circulating water pump has been running for 10–20 minutes, the drain outlet is opened, and the system is continuously circulated and cleaned while simultaneously draining the waste until no more waste is discharged. Fifth, add 10-50L of alcohol to the separation vessel, turn on the circulating water pump for circulation cleaning, and then open the drain port. Continue circulation cleaning and draining until no more dirt is discharged.

6. The high-efficiency cleaning process for the supercritical extraction equipment according to claim 5, characterized in that: In step S3, when the separation system contains two separation vessels and a second carbon dioxide extraction and cleaning is performed, the pressure of the first separation vessel is set to 7-16 MPa and the temperature to 40-50°C, and the pressure of the second separation vessel is set to 3-5 MPa and the temperature to 50-60°C.

7. The high-efficiency cleaning process for the supercritical extraction equipment according to claim 3, characterized in that: In step S4, the first step involves pumping alkaline water with a concentration of 1% to 5% and a temperature of 50 to 80°C into the tail gas recovery system. The circulating water pump is turned on for 10 to 30 minutes and then stopped. After soaking for 0.5 to 1 hour, the circulating water pump is turned on again for 0.1 to 0.5 hours. Then the drain outlet is opened, and the system is circulated and cleaned while draining the waste until no waste is discharged. The second step involves preparing a 50%–60% alcohol solution and adding 4%–5% polyglycerol fatty acid ester to obtain an activator. The activator is then pumped into the exhaust gas recovery system. After the circulating water pump has been running for 10–20 minutes, the drain outlet is opened, and the system is continuously circulated and cleaned while simultaneously draining the waste until no more waste is discharged. The third step involves adding 10-50L of alcohol to the exhaust gas recovery system filter, turning on the circulating water pump for cleaning, and then opening the drain outlet. The system continues to clean and drain simultaneously until no more contaminants are discharged.

8. The efficient cleaning process for supercritical extraction equipment according to claim 5 or 7, characterized in that: In the alcohol circulation cleaning steps S3 and S4, flowing clean water is added at the same time as alcohol is added. The clean water is pumped into the separation vessel to mix with the alcohol for cleaning. The flow rate of the circulating water pump is adjusted to 10-20 L / h, so that the alcohol forms an alcohol solvent with a continuously decreasing concentration gradient under the addition of clean water. After the circulating water pump is turned on for 10-20 minutes, the drain port is opened, and the sludge is discharged while the circulation cleaning is being carried out until no dirt is discharged.

9. The high-efficiency cleaning process for the supercritical extraction equipment according to claim 3, characterized in that: In step S5, after connecting the extraction system, separation system, and tail gas recovery system, the carbon dioxide in the intermediate storage tank is emptied, new carbon dioxide is added, and the equipment is started for carbon dioxide no-load circulation cleaning. The extraction pressure is set to 20-30 MPa, the extraction temperature to 40-50℃, the separation pressure to 6-10 MPa, the extraction flow rate to 1500-2500 kg / h, and the cleaning time to 0.5-1 h, until no impurities are discharged from the separation vessel outlet. Then, the machine is stopped and the system is shut down to maintain pressure.

10. The high-efficiency cleaning process for the supercritical extraction equipment according to claim 1, characterized in that: Steps S2, S3, and S4 are performed simultaneously.

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