Efficient cleaning method of supercritical extraction equipment for grease extraction

Abstract

The invention discloses an efficient cleaning method of supercritical extraction equipment for grease extraction, which comprises the following steps: closing valves of connecting pipelines at two ends of each heat exchanger and two ends of each separation kettle, separating each heat exchanger from each separation kettle, respectively injecting alkaline water into each heat exchanger and each separation kettle for soaking, and then cleaning the heat exchangers and the separation kettles; after soaking is completed, water is used for washing, and compressed air is used for purging; the equipment is adjusted to be in a start-up state, different cleaning media are sequentially injected to circularly clean the extraction system, and the cleaning media are alkaline water, alcohol, clear water and carbon dioxide sequentially according to the circulating cleaning sequence; and before and after the alkaline water is used for carrying out circulating cleaning, carbon dioxide in all equipment and pipelines of the extraction system needs to be emptied under the shutdown state of the extraction system, and carbon dioxide is supplemented in the intermediate storage tank again after the carbon dioxide is emptied. By means of the precise and effective cleaning technology, the labor requirement and time consumption are optimized to the maximum extent, and finally the efficient cleaning effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of supercritical extraction equipment cleaning, and in particular to a high-efficiency cleaning method for supercritical extraction equipment for oil extraction. Background Art

[0002] With the continuous innovation of oil extraction technology, supercritical extraction technology has stood out in the field of oil extraction. In recent years, after the National Industrial Structure Adjustment Guidance Catalogue listed supercritical extraction technology in the direction of oil extraction as an encouraged project, the industrialization of supercritical extraction technology in the field of oil extraction has been continuously expanded, and the extraction equipment has developed to a maximum scale of 5200L×3 in terms of model. In terms of application, it has been widely promoted in local crop production enterprises such as counties and cities and large oil manufacturers on the market. However, supercritical extraction of oil crops is an efficient extraction method, but after supercritical extraction uses the material, it is indeed very difficult to clean the equipment. First of all, most of the equipment in the supercritical extraction system is a confined space, and the pipeline is long and has corners. The equipment is large, the structure is complex and irregular, and there are many coils or tubes in the heating device. The cleaning difficulty is very large, the cleaning of the entire equipment is time-consuming and labor-intensive, and the cleaning effect is poor. At present, the extraction equipment process of supercritical CO2 oil extraction is only general alkaline water circulation cleaning or solvent circulation cleaning, but the cleaning effect is still not ideal. Therefore, it is extremely urgent to find a method that can achieve efficient cleaning of supercritical extraction equipment. Summary of the invention

[0003] In order to solve the above problems, the object of the present invention is to provide a highly efficient cleaning method of supercritical extraction equipment for oil extraction, which can achieve highly efficient cleaning of the extraction equipment.

[0004] The purpose of the present invention is achieved through the following technical solutions: An efficient cleaning method for supercritical extraction equipment for oil extraction comprises the following steps: First, clean the heat exchanger and separation kettle.

[0005] When cleaning the heat exchanger, close or cut off the valves connecting the pipes at both ends of each heat exchanger to make each heat exchanger independent, then disassemble the gas flange at one end of the heat exchanger, inject 3-10% hot alkaline water into each tube until it overflows, and reinstall the disassembled flange. The alkaline water temperature is 50-60℃, the hot water temperature of the heat exchanger jacket is 50-60℃, and the soaking time is 1-2h. After the soaking is completed, disassemble the flanges at both ends and rinse them with a high-pressure water gun. Finally, use compressed air to blow away the accumulated liquid in the tubes, and then reinstall the flanges to clean the impurities such as grease in the tubes. Because the supercritical extraction equipment is dissolved in the extraction kettle during the extraction process and separated in the separation kettle, the separated materials are very likely to gather at the heat exchanger due to the complex structure of the heat exchanger. The long-term high temperature causes the heat exchanger to have many impurities and is difficult to clean. When cleaning, clean this part first to reduce the secondary pollution of this part of the material to other parts of the equipment, which can more effectively improve the cleaning efficiency.

[0006] Clean the separation kettle, close or cut off the valves connecting the two ends of each separation kettle, make each separation kettle independent, open the valve of the separation kettle to discharge the carbon dioxide gas, open the kettle cover, pour 3-10% hot alkaline water until it reaches one-third of the volume of the separation kettle, the alkaline water temperature is 50-60℃, the hot water temperature of the separation kettle jacket is 50-60℃, and the soaking time is 1-2h. After the soaking is completed, rinse it with a high-pressure water gun and blow it clean with compressed air until all the sewage is discharged. Because the supercritical extraction equipment is dissolved in the extraction kettle during the extraction process and separated in the separation kettle, the separated materials in the separation kettle are easy to gather. The long-term high temperature causes the separation kettle to have many impurities and is difficult to clean. When cleaning, this part is cleaned again to reduce the secondary pollution of this part of the material to other parts of the equipment, which can more effectively improve the cleaning efficiency.

[0007] Secondly, the equipment is turned on, and different cleaning media are injected in sequence to perform cyclic cleaning on the extraction system. The cleaning media are alkaline water, alcohol, clean water and carbon dioxide in the order of cyclic cleaning.

[0008] The alkaline water circulation cleaning is to clean most of the oily substances in the extraction equipment. After the new carbon dioxide is injected into the intermediate storage tank, an equal amount of alkaline solution is poured into each extraction kettle, and the kettle cover is closed to adjust the equipment to the start state. When the equipment is turned on, each extraction kettle is adjusted to the operation state of series connection in sequence. After the cleaning of each extraction kettle is completed in series at the same time, it is adjusted to the series connection state of the first and last extraction kettles for cleaning, and all extraction pipelines can be cleaned in sequence. The alkaline water cleaning process is: extraction pressure 20-30MPa, extraction temperature 50-60℃, separation pressure 6-10MPa, separation temperature 50-60℃, extraction flow rate 1500-2500kg / h, alkaline water concentration 3-10%, alkaline water volume 50-100L, cleaning time 1-4h.

[0009] The alcohol circulation cleaning, after the new carbon dioxide is injected into the intermediate storage tank, the same amount of alcohol is poured into the three extraction kettles respectively, the kettle cover is closed and the equipment is adjusted to the start state, the equipment is in the start state, and the extraction kettles are adjusted to the running state of series connection in sequence. After the extraction kettles are cleaned in series at the same time, they are adjusted to the series connection state of the first and last extraction kettles for cleaning, and the cleaning of all extraction pipelines can be completed in sequence. During the cleaning, an additive pump is used to adjust the flow rate of the additive pump, and the water pumped by the additive pump dilutes the alcohol to form different concentration gradients to clean the pigment. The amount of alcohol added is 30-60L, and the cleaning time is 1-4h. In the cleaning time period of 1-2h, the additive pump is used to add clean water, and the addition amount is 5-60L / h, forming an alcohol concentration change of 80-40%. In the cleaning time period of 2-4h, the additive pump is used to add clean water, and the addition amount is 20-60L / h, forming an alcohol concentration change of 40-20%, and cleaning is carried out.

[0010] The clean water circulation cleaning is to neutralize the alkali solution and impurities remaining in the equipment. Pour an equal amount of clean water into the three extraction kettles respectively, close the kettle cover and adjust the equipment to the start state. When the equipment is turned on, adjust each extraction kettle in series operation. After the cleaning of each extraction kettle is completed at the same time, adjust the first and last extraction kettles in series for cleaning, and then complete the cleaning of all extraction pipelines in sequence. The clean water cleaning process is: clean water volume: 100-200L, extraction pressure 20-30MPa, extraction temperature 40-50℃, separation pressure 6-10MPa, separation temperature 40-50℃, extraction flow rate 1500-2500kg / h, cleaning time 1-4h, until the pH range is 7-8.

[0011] The carbon dioxide circulation cleaning is to open all the emptying pipes to drain the clean water after the cleaning water circulation cleaning is completed, until no water flows out, then close all the emptying valves, adjust the equipment to the start-up state, and use carbon dioxide for no-load circulation cleaning when the equipment is turned on. The cleaning process is: extraction pressure 20-30MPa, extraction temperature 40-50℃, separation pressure 6-10MPa, separation temperature 40-50℃, extraction flow rate 1500-2500kg / h, cleaning time 1-4h, until no impurities are discharged from the separation kettle, shut down, close the system inlet and outlet valves to maintain pressure until the next time the equipment is used, open the emptying valve again to discharge sewage, and it can be used directly after the sewage is discharged. After the cleaning is completed, the pressure maintenance operation is performed to fill the internal space of the equipment with carbon dioxide, isolate oxygen, and prevent bacteria from growing.

[0012] Finally, before and after the alkaline water is used for circulating cleaning, the extraction system must be shut down, and the unopened gas lines of the equipment must be opened to drain the carbon dioxide from the equipment and pipelines of the extraction system (mainly the extraction kettle, pipelines, intermediate storage tanks, etc.). After draining, the carbon dioxide must be refilled in the intermediate storage tank.

[0013] The reason for emptying the equipment before using alkaline water for circulating cleaning is that the carbon dioxide in each device is the remaining carbon dioxide from the previous extraction. The carbon dioxide gas contains most of the impurities such as oil and water. Emptying is to prevent the next circulating cleaning (alkaline water cleaning) from being incomplete. After the carbon dioxide in the intermediate storage tank is emptied, new carbon dioxide is added.

[0014] The last emptying after circulating cleaning with alkaline water is because the carbon dioxide in each equipment is the residue of circulating cleaning with alkaline water. The carbon dioxide gas contains most of the alkaline water and other impurities, with a pH range of 10-14. Emptying reduces the cleaning time of subsequent circulating cleaning.

[0015] In addition, before replacing the cleaning medium, the previous cleaning medium must be drained and then the cleaning medium must be injected with the extraction system shut down.

[0016] The beneficial effects of the present invention are: The present invention is easy to operate and can achieve maximum optimization of labor requirements and time consumption through precise and effective cleaning processes, ultimately achieving efficient cleaning effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0018] Figure 1 It is a connection diagram of existing oil supercritical carbon dioxide extraction equipment.

[0019] Figure 2 This is a cleaning flow chart of the oil supercritical carbon dioxide extraction equipment of the present invention. DETAILED DESCRIPTION

[0020] The following is an explanation of the implementation of the present invention by specific specific embodiments. People familiar with the technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] like Figure 1As shown, the equipment of the existing supercritical CO2 extraction system for oils and fats mainly includes an intermediate storage tank, an extraction kettle, a separation kettle, a heat exchanger, and corresponding connecting pipes and valves, etc. There are three extraction kettles (marked as 1, 2, and 3 respectively) and they are connected in series through pipes in sequence. There are two separation kettles and they are also connected in series through pipes in sequence. The intermediate storage tank, the extraction kettle, and the separation kettle are connected in series through gas pipelines in sequence, and at the same time, the gas outlet of the last separation kettle is connected to the intermediate storage tank to form a circulating gas circuit. Heat exchangers are installed in the pipelines between the intermediate storage tank and the extraction kettle, between the extraction kettle and the separation kettle, and between the two separation kettles. The above equipment is commonly used equipment for supercritical CO2 extraction. Example 1

[0022] like Figure 2 As shown, this embodiment provides an efficient cleaning method for a supercritical carbon dioxide extraction system for oils and fats, which is mainly used to clean various equipment and pipelines on a supercritical CO2 extraction system that has extracted oils and fats. The cleaning steps are as follows: S1. Clean the heat exchanger, close or cut off the valves connecting the pipes at both ends of each heat exchanger to make each heat exchanger independent, then disassemble the gas flange at one end of each heat exchanger, inject 5% hot alkaline water into each tube until it overflows, and reinstall the disassembled flange. The alkaline water temperature is 50℃, the hot water temperature of the heat exchanger jacket is 50℃, and the soaking time is 1h. After the soaking is completed, disassemble the flanges at both ends and rinse them with a high-pressure water gun. Finally, use compressed air to blow away the accumulated liquid in the tube, reinstall the flanges, and wait for standby.

[0023] S2. Clean the separation kettle, close or cut off the valves connecting the pipes at both ends of each separation kettle to make each separation kettle independent, open the valve connecting the separation kettle to the extract to discharge the carbon dioxide gas, open the kettle cover, pour in 5% hot alkaline water until it reaches one-third of the volume of the separation kettle, the alkaline water temperature is 50℃, the hot water temperature of the separation kettle jacket is 50℃, and the soaking time is 1h. After the soaking is completed, rinse it with a high-pressure water gun and blow it clean with compressed air until all the sewage is discharged and wait for standby.

[0024] S3. Empty and replenish carbon dioxide for the first time: Open the valves of each device and pipeline, and empty the carbon dioxide in the gas path of the equipment that is not opened (mainly the extraction kettle, pipeline, intermediate storage tank, etc.). After emptying the carbon dioxide in the intermediate storage tank, refill the carbon dioxide in the intermediate storage tank and wait for standby.

[0025] S4. Alkaline water circulation cleaning, pour equal amounts of alkali solution into the three extraction kettles respectively, close the kettle cover and adjust the equipment to the start state. When the equipment is turned on, adjust it according to the operation state of 1 series 2 series 3 (to connect the three extraction kettles in series). After the three extraction kettles are cleaned in series at the same time, adjust it to 3 series 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning, and then complete the cleaning of all extraction pipelines in sequence. The alkaline water cleaning process is: 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, cleaning time 2h.

[0026] S5. Empty and replenish carbon dioxide for the second time: Open the valves of each device and pipeline again, empty the carbon dioxide in each device and pipeline, and after emptying the carbon dioxide in the intermediate storage tank, refill the carbon dioxide in the intermediate storage tank and wait for standby.

[0027] S6. Alcohol circulation cleaning: After the new carbon dioxide is injected into the intermediate storage tank, an equal amount of alcohol is poured into the three extraction kettles respectively, and the kettle cover is closed to adjust the equipment to the start state. When the equipment is in the start state, it is adjusted according to the operation state of 1 series, 2 series and 3 (the three extraction kettles are connected in series). After the three extraction kettles are cleaned in series at the same time, they are adjusted to 3 series and 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning. Only in this way can the cleaning of all extraction pipelines be completed in sequence. When cleaning, an additive pump is used to adjust the flow rate of the additive pump. The water pumped in by the additive pump dilutes the alcohol to form different concentration gradients to clean the pigment. The alcohol concentration is 80%, the amount of alcohol added is 50L, and the cleaning time is 4h. In the cleaning period of 1-2h, the additive pump is used to add clean water at an amount of 50L / h, so that the alcohol concentration gradually changes from 80% to 40%. In the cleaning period of 2-4h, the additive pump is continued to be used to add clean water at an amount of 50L / h, so that the alcohol concentration gradually changes from 40% to 20%, and cleaning is carried out.

[0028] S7. Cleaning with clean water circulation: Pour 100L of clean water into the three extraction kettles respectively, close the kettle cover and adjust the equipment to the start state. When the equipment is turned on, adjust it according to the operation state of 1 series 2 series 3 (connect the three extraction kettles in series). After the three extraction kettles are cleaned in series at the same time, adjust it to 3 series 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning, and then complete the cleaning of all extraction pipelines in sequence. Clean water cleaning process is: 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 range is 7-8, waiting for standby.

[0029] S8. Carbon dioxide circulation cleaning: After the final cleaning water circulation cleaning is completed, open all drain pipes to drain the clean water until no water flows out, adjust the equipment to the start state, use carbon dioxide for no-load circulation cleaning, and the drain valve is in the open state during the pressure increase process, mainly to allow carbon dioxide to bring out the water. After 2-3 minutes, close all drain valves and start the cycle. The cleaning process is: 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 kettle, shut down, close the system inlet and outlet valves to maintain pressure until the next time the equipment is used, open the drain valve again to discharge sewage, and it can be used directly after the sewage is discharged. Example 2

[0030] like Figure 2 As shown, this embodiment provides an efficient cleaning method for a supercritical carbon dioxide extraction system for oils and fats, which is mainly used to clean various equipment and pipelines on a supercritical CO2 extraction system that has extracted oils and fats. The cleaning steps are as follows: S1. Clean the heat exchanger, close or cut off the valves connecting the pipes at both ends of each heat exchanger to make each heat exchanger independent, then disassemble the gas flange at one end of each heat exchanger, inject 5% hot alkaline water into each tube until it overflows, and reinstall the disassembled flange. The alkaline water temperature is 55℃, the hot water temperature of the heat exchanger jacket is 55℃, and the soaking time is 2h. After the soaking is completed, disassemble the flanges at both ends and rinse them with a high-pressure water gun. Finally, use compressed air to blow away the accumulated liquid in the tube, reinstall the flanges, and wait for standby.

[0031] S2. Clean the separation kettle, close or cut off the valves connecting the pipes at both ends of each separation kettle to make each separation kettle independent, open the valve connecting the separation kettle to the extract to discharge the carbon dioxide gas, open the kettle cover, pour in 5% hot alkaline water until it reaches one-third of the volume of the separation kettle, the alkaline water temperature is 55℃, the hot water temperature of the separation kettle jacket is 55℃, and the soaking time is 2h. After the soaking is completed, rinse it with a high-pressure water gun and blow it clean with compressed air until all the sewage is discharged and wait for standby.

[0032] S3. Empty and replenish carbon dioxide for the first time: Open the valves of each device and pipeline, and empty the carbon dioxide in the gas path of the equipment that is not opened (mainly the extraction kettle, pipeline, intermediate storage tank, etc.). After emptying the carbon dioxide in the intermediate storage tank, refill the carbon dioxide in the intermediate storage tank and wait for standby.

[0033] S4. Alkaline water circulation cleaning, pour equal amounts of alkali solution into the three extraction kettles respectively, close the kettle cover and adjust the equipment to the start state. When the equipment is turned on, adjust it according to the operation state of 1 series 2 series 3 (to connect the three extraction kettles in series). After the three extraction kettles are cleaned in series at the same time, adjust it to 3 series 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning, and then complete the cleaning of all extraction pipelines in sequence. The alkaline water cleaning process is: extraction pressure 25MPa, extraction temperature 55℃, separation pressure 9MPa, separation temperature 55℃, extraction flow rate 2000kg / h, alkaline water concentration 5%, alkaline water volume 100L, cleaning time 1h.

[0034] S5. Empty and replenish carbon dioxide for the second time: Open the valves of each device and pipeline again, empty the carbon dioxide in each device and pipeline, and after emptying the carbon dioxide in the intermediate storage tank, refill the carbon dioxide in the intermediate storage tank and wait for standby.

[0035] S6. Alcohol circulation cleaning: After the new carbon dioxide is injected into the intermediate storage tank, an equal amount of alcohol is poured into the three extraction kettles respectively, and the kettle cover is closed to adjust the equipment to the start state. When the equipment is in the start state, it is adjusted according to the operation state of 1 series, 2 series and 3 (the three extraction kettles are connected in series). After the three extraction kettles are connected in series and cleaned at the same time, they are adjusted to 3 series and 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning. Only in this way can the cleaning of all extraction pipelines be completed in sequence. When cleaning, an additive pump is used to adjust the flow rate of the additive pump. The water pumped in by the additive pump dilutes the alcohol to form different concentration gradients to clean the pigment. The alcohol concentration is 80%, the amount of alcohol added is 40L, and the cleaning time is 3h. In the cleaning period of 1-2h, the additive pump is used to add clean water at an amount of 40L / h, so that the alcohol concentration gradually changes from 80% to 40%. In the cleaning period of 2-3h, the additive pump is continued to be used to add clean water at an amount of 80L / h, so that the alcohol concentration gradually changes from 40% to 20%, and cleaning is carried out.

[0036] S7. Cleaning with clean water circulation: Pour 100L of clean water into the three extraction kettles respectively, close the kettle cover and adjust the equipment to the start state. When the equipment is turned on, adjust it according to the operation state of 1 series 2 series 3 (connect the three extraction kettles in series). After the three extraction kettles are cleaned in series at the same time, adjust it to 3 series 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning, and then complete the cleaning of all extraction pipelines in sequence. Clean water cleaning process is: clean water volume: 100L, extraction pressure 25MPa, extraction temperature 55℃, separation pressure 8MPa, separation temperature 55℃, extraction flow rate 2000kg / h, cleaning time 1h, until the PH range is 7-8, waiting for standby.

[0037] S8. Carbon dioxide circulation cleaning: After the final cleaning water circulation cleaning is completed, open all drain pipes to drain the clean water until no water flows out, adjust the equipment to the start state, use carbon dioxide for no-load circulation cleaning, and the drain valve is in the open state during the pressure increase process, mainly to allow carbon dioxide to bring out the water. After 2-3 minutes, close all drain valves and start the cycle. The cleaning process is: extraction pressure 25MPa, extraction temperature 55℃, separation pressure 8MPa, separation temperature 55℃, extraction flow rate 2000kg / h, cleaning time 1h, until no impurities are discharged from the separation kettle, shut down, close the system inlet and outlet valves to maintain pressure, until the next time the equipment is used, open the drain valve again to discharge sewage, and it can be used directly after the sewage is discharged. Example 3

[0038] like Figure 2 As shown, this embodiment provides an efficient cleaning method for a supercritical carbon dioxide extraction system for oils and fats, which is mainly used to clean various equipment and pipelines on a supercritical CO2 extraction system that has extracted oils and fats. The cleaning steps are as follows: S1. Clean the heat exchanger, close or cut off the valves connecting the pipes at both ends of each heat exchanger to make each heat exchanger independent, then disassemble the gas flange at one end of each heat exchanger, inject 8% hot alkaline water into each tube until it overflows, and reinstall the disassembled flange. The alkaline water temperature is 60℃, the hot water temperature of the heat exchanger jacket is 60℃, and the soaking time is 2h. After the soaking is completed, disassemble the flanges at both ends and rinse them with a high-pressure water gun. Finally, use compressed air to blow away the accumulated liquid in the tube, reinstall the flanges, and wait for standby.

[0039] S2. Clean the separation kettle, close or cut off the valves connecting the pipes at both ends of each separation kettle to make each separation kettle independent, open the valve connecting the separation kettle to the extract to discharge the carbon dioxide gas, open the kettle cover, pour in 8% hot alkaline water until it reaches one-third of the volume of the separation kettle, the alkaline water temperature is 60℃, the hot water temperature of the separation kettle jacket is 60℃, and the soaking time is 2h. After the soaking is completed, rinse it with a high-pressure water gun and blow it clean with compressed air until all the sewage is discharged and wait for standby.

[0040] S3. Empty and replenish carbon dioxide for the first time: Open the valves of each device and pipeline, and empty the carbon dioxide in the gas path of the equipment that is not opened (mainly the extraction kettle, pipeline, intermediate storage tank, etc.). After emptying the carbon dioxide in the intermediate storage tank, refill the carbon dioxide in the intermediate storage tank and wait for standby.

[0041] S4. Alkaline water circulation cleaning, pour equal amounts of alkali solution into the three extraction kettles respectively, close the kettle cover and adjust the equipment to the start state. When the equipment is turned on, adjust it according to the operation state of 1 series 2 series 3 (to connect the three extraction kettles in series). After the three extraction kettles are cleaned in series at the same time, adjust it to 3 series 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning, and then complete the cleaning of all extraction pipelines in sequence. The alkaline water cleaning process is: extraction pressure 30MPa, extraction temperature 60℃, separation pressure 10MPa, separation temperature 60℃, extraction flow rate 2500kg / h, alkaline water concentration 8%, alkaline water volume 150L, ​​cleaning time 1h.

[0042] S5. Empty and replenish carbon dioxide for the second time: Open the valves of each device and pipeline again, empty the carbon dioxide in each device and pipeline, and after emptying the carbon dioxide in the intermediate storage tank, refill the carbon dioxide in the intermediate storage tank and wait for standby.

[0043] S6. Alcohol circulation cleaning: After the new carbon dioxide is injected into the intermediate storage tank, an equal amount of alcohol is poured into the three extraction kettles respectively, and the kettle cover is closed to adjust the equipment to the start state. When the equipment is in the start state, it is adjusted according to the operation state of 1 series, 2 series and 3 (the three extraction kettles are connected in series). After the three extraction kettles are cleaned in series at the same time, they are adjusted to 3 series and 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning. Only in this way can the cleaning of all extraction pipelines be completed in sequence. When cleaning, an additive pump is used to adjust the flow rate of the additive pump. The water pumped in by the additive pump dilutes the alcohol to form different concentration gradients to clean the pigment. The alcohol concentration is 80%, the amount of alcohol added is 60L, and the cleaning time is 4h. In the cleaning period of 1-2h, the additive pump is used to add clean water at an amount of 60L / h, so that the alcohol concentration gradually changes from 80% to 40%. In the cleaning period of 2-4h, the additive pump is continued to be used to add clean water at an amount of 60L / h, so that the alcohol concentration gradually changes from 40% to 20%, and cleaning is carried out.

[0044] S7. Cleaning with clean water circulation: Pour 150L of clean water into the three extraction kettles respectively, close the kettle cover and adjust the equipment to the start state. When the equipment is turned on, adjust it according to the operation state of 1 series 2 series 3 (connect the three extraction kettles in series). After the three extraction kettles are cleaned in series at the same time, adjust it to 3 series 1 (the tail extraction kettle is connected in series with the head extraction kettle) for cleaning, and then complete the cleaning of all extraction pipelines in sequence. The clean water cleaning process is: clean water volume: 150L, ​​extraction pressure 30MPa, extraction temperature 60℃, separation pressure 9MPa, separation temperature 60℃, extraction flow rate 2500kg / h, cleaning time 1h, until the PH range is 7-8, waiting for standby.

[0045] S8. Carbon dioxide circulation cleaning: After the final cleaning water circulation cleaning is completed, open all drain pipes to drain the clean water until no water flows out, adjust the equipment to the start state, use carbon dioxide for no-load circulation cleaning, and the drain valve is in the open state during the pressure increase process, mainly to allow carbon dioxide to bring out the water. After 2-3 minutes, close all drain valves and start the cycle. The cleaning process is: extraction pressure 30MPa, extraction temperature 60℃, separation pressure 9MPa, separation temperature 60℃, extraction flow rate 2500kg / h, cleaning time 1h, until no impurities are discharged from the separation kettle, shut down, close the system inlet and outlet valves to maintain pressure until the next time the equipment is used, open the drain valve again to discharge sewage, and it can be used directly after the sewage is discharged.

[0046] Other aspects of the present invention that are not described in detail are all conventional techniques known to those skilled in the art.

[0047] It should be noted that the terms "comprises", "includes" or any other variations are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0048] The protection scope of the present invention is not limited to the technical solutions disclosed in the specific implementation methods. Any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An efficient cleaning method for supercritical extraction equipment for oil extraction, characterized in that: The method comprises the following steps: closing the valves of the connecting pipelines at both ends of each heat exchanger and at both ends of each separation kettle, separating each heat exchanger and each separation kettle, respectively injecting alkaline water into each heat exchanger and each separation kettle for soaking, and after the soaking, flushing with water, and then blowing clean with compressed air; thereafter, adjusting the equipment to the start state, and injecting different cleaning media in turn to circulate and clean the extraction system, wherein the cleaning media are alkaline water, alcohol, clean water and carbon dioxide in the order of circulatory cleaning; and before and after the circulatory cleaning with alkaline water, the carbon dioxide in each equipment and pipeline of the extraction system needs to be emptied when the extraction system is shut down, and then the carbon dioxide is replenished in the intermediate storage tank after emptying.

2. The efficient cleaning method of supercritical extraction equipment for oil extraction according to claim 1, characterized in that: The alkaline water used for immersion cleaning of the heat exchanger and the separation kettle in an independent state is hot alkaline water with a temperature of 50-60°C and a mass concentration of 3-10%. The immersion time is 1-2h. At the same time, during the immersion process, the hot water temperature of the heat exchanger jacket and the separation kettle jacket are both 50-60°C.

3. The efficient cleaning method of supercritical extraction equipment for oil extraction according to claim 1, characterized in that: Before replacing the cleaning medium, the previous cleaning medium must be drained and then the cleaning medium must be injected with the extraction system shut down.

4. The efficient cleaning method of supercritical extraction equipment for oil extraction according to claim 2, characterized in that: Among the cleaning media injected into the extraction system, alkaline water, alcohol and clean water are injected into the extraction kettle, and carbon dioxide is injected into the intermediate storage tank.

5. The efficient cleaning method for supercritical extraction equipment for oil extraction according to claim 1, characterized in that: Set the equipment to the start-up state and inject alkaline water to circulate and clean the extraction system. The process is: extraction pressure 20-30MPa, extraction temperature 50-60℃, separation pressure 6-10MPa, separation temperature 50-60℃, extraction flow rate 1500-2500kg / h, alkaline water concentration 3-10%, alkaline water volume 50-100L, cleaning time 1-4h.

6. The efficient cleaning method for supercritical extraction equipment for oil extraction according to claim 1, characterized in that: Turn on the equipment and inject alcohol to circulate and clean the extraction system. Then, water is pumped in to dilute the alcohol to form different concentration gradients of alcohol to clean the pigment inside the extraction system.

7. The efficient cleaning method for supercritical extraction equipment for oil extraction according to claim 6, characterized in that: Set the equipment to the start-up state and inject alcohol to circulate and clean the extraction system. The amount of alcohol added is 30-60L and the cleaning time is 1-4h. During the cleaning period of 1-2h, use the adding pump to add clean water at a rate of 5-60L / h, forming an alcohol concentration change of 80-40%. During the cleaning period of 2-4h, use the adding pump to add clean water at a rate of 20-60L / h, forming an alcohol concentration change of 40-20%, and then clean it.

8. The efficient cleaning method for supercritical extraction equipment for oil extraction according to claim 1, characterized in that: Turn on the equipment and inject clean water to circulate and clean the extraction system. The process is: clean water volume 100-200L, extraction pressure 20-30MPa, extraction temperature 40-50℃, separation pressure 6-10MPa, separation temperature 40-50℃, extraction flow rate 1500-2500kg / h, cleaning time 1-4h, until the pH is 7-8.

9. The efficient cleaning method for supercritical extraction equipment for oil extraction according to claim 1, characterized in that: Set the equipment to the start-up state and use carbon dioxide for no-load circulation cleaning. The process is: extraction pressure 20-30MPa, extraction temperature 40-50℃, separation pressure 6-10MPa, separation temperature 40-50℃, extraction flow rate 1500-2500kg / h, cleaning time 1-4h, until no impurities are discharged from the separation kettle, shut down, close the inlet and outlet valves of the extraction system to maintain pressure until the next time the extraction system is used, then open the drain valve again to drain the sewage. After the sewage is drained, it can be used directly.

10. The efficient cleaning method for supercritical extraction equipment for oil extraction according to claim 1, characterized in that: When there are three or more extraction kettles, turn on the equipment and inject different cleaning media in sequence to perform cyclic cleaning on the extraction system. First, clean all the extraction kettles in series in sequence. After the cleaning is completed, switch the first and last two extraction kettles in series for cleaning.

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