A method and system for separating a liquid mixture

Abstract

The present disclosure relates to a method and a system for separating a liquid mixture. By setting the operating pressure at the feed point of the extract separation device such that the sum of it and the pressure generated by the static liquid column height from the feed point to the extract mixing device is always higher than the bubble point pressure of the mixed material in the simulated moving bed adsorption device at the operating temperature, and setting the operating pressure at the feed point of the raffinate separation device such that the sum of it and the pressure generated by the static liquid column height from the feed point to the raffinate mixing device is always higher than the bubble point pressure of the mixed material in the simulated moving bed adsorption device at the operating temperature, it is possible to avoid the gasification of the mixed material caused by the pressure loss in the simulated moving bed adsorption device, which may damage the internal components of the adsorption tower and the solid adsorbent, enabling it to achieve inherent safety, avoid economic losses, and at the same time significantly reduce the overall energy consumption of the device.

Description

Technical Field

[0001] The present disclosure relates to the field of separation of liquid mixtures, and in particular, to a method and a system for separating liquid mixtures. Background Art

[0002] The simulated moving bed adsorption column system is a complex and highly efficient separation device, which is widely used in many fields such as petrochemical, food, and medicine. In the petrochemical industry, it is commonly used for the production of para-xylene (PX), meta-xylene (MX), ethylbenzene (EB), and the separation of normal paraffins and isoparaffins, the separation of alkanes and aromatics, and the separation of olefins, etc.

[0003] The adsorption column system is filled with solid adsorbents, process materials, and internal components, which is the core equipment. The solid adsorbents are loaded in multiple layers in the adsorption column and separated by internal components in the middle, which play the role of supporting the adsorbents and mixing and distributing the process materials. The solid adsorbents and internal components are costly. After the extract and raffinate are withdrawn from the adsorption column system, they enter the downstream extract separation device and raffinate separation device respectively. In the prior art, the extract separation device and raffinate separation device usually operate under slightly positive pressure. When the operation is improper, a large amount of the extract and raffinate are withdrawn and enter the subsequent separation device, which will cause the operating pressure of the adsorption column system to drop sharply. If appropriate measures are not taken to intervene, the operating pressure will continue to drop until it reaches the bubble point pressure of the materials in the column, causing the materials in the column to vaporize, damaging the solid adsorbents and internal components, and causing huge economic losses.

[0004] In order to prevent the adsorption column system from losing pressure and damaging the adsorbents and internal components, the prior art usually sets up an emergency nitrogen supplement device, which opens the valve when the pressure of the adsorption column system drops to a certain value, and keeps the pressure of the adsorption column system by supplementing nitrogen to the system. However, the emergency nitrogen supplement device is relatively complex and there is a possibility of misoperation. Once the nitrogen valve is wrongly opened, it will also damage the adsorption column system. Summary of the Invention

[0005] The purpose of the present disclosure is to provide a method and a system for separating liquid mixtures.

[0006] To achieve the above purpose, the first aspect of the present disclosure provides a method for separating liquid mixtures, the method comprising:

[0007] S1. Contacting a mixed material containing a raw material and a desorbent with a solid adsorbent in a simulated moving bed adsorption device to perform liquid-liquid separation treatment, obtaining an extract and a raffinate;

[0008] S2. Passing the extract obtained in step S1 through an extract mixing device and then entering an extract separation device to obtain a crude product and a desorbent;

[0009] S3. Pass the raffinate obtained in step S1 through a raffinate mixing device and then into a raffinate separation device to obtain a raffinate product and a desorbent;

[0010] wherein, P 4 +P 4 ’ > P 0 , P 5 +P 5 ’ > P 0 , P 2 > P 4 +P 4 ’, P 3 > P 5 +P 5 ’;

[0011] P 0 is the bubble point pressure of the mixed material at the first operating temperature of the simulated moving bed adsorption device;

[0012] P 2 is the second operating pressure of the extract mixing device;

[0013] P 3 is the third operating pressure of the raffinate mixing device;

[0014] P 4 is the fourth operating pressure at the feed point of the extract separation device;

[0015] P 4 ’ is the pressure generated by the static liquid column height between the feed point of the extract separation device and the extract mixing device;

[0016] P 5 is the fifth operating pressure at the feed point of the raffinate separation device;

[0017] P 5 ’ is the pressure generated by the static liquid column height between the feed point of the raffinate separation device and the raffinate mixing device.

[0018] Optionally, the first operating temperature of the simulated moving bed adsorption device is 60 - 230 °C, and the first operating pressure is 0.6 - 2.8 MPaG.

[0019] Optionally, the second operating temperature of the extract mixing device is 60 - 230 °C, and the second operating pressure is 0.26 - 2.0 MPaG; and the second operating pressure is higher than the bubble point pressure of the mixed material at the first operating temperature.

[0020] Optionally, the third operating temperature of the raffinate mixing device is 60 - 230 °C, and the third operating pressure is 0.26 - 2.0 MPaG; and the third operating pressure is higher than the bubble point pressure of the mixed material at the first operating temperature.

[0021] Optionally, the fourth operating temperature at the top of the extract separation device is 80 - 220 °C; the sixth operating pressure at the top of the extract separation device is 0.2 - 1.5 MPaG.

[0022] Optionally, the fifth operating temperature at the top of the raffinate separation device is 80 - 220 °C; the seventh operating pressure at the top of the raffinate separation device is 0.2 - 1.5 MPaG.

[0023] Optionally, the method further includes: returning the desorbent separated from the extract separation device and / or the raffinate separation device to the simulated moving bed adsorption device for continued use.

[0024] Optionally, the desorbent includes one or more of toluene, methylcyclohexane, p - diethylbenzene, and n - nonane; the simulated moving bed adsorption device includes one or two simulated moving bed adsorption towers, an adsorption tower circulation pump, an adsorption tower bed layer pipeline, and a device and a control system for switching the connection position of the adsorption tower bed layer pipeline with the interface of the simulated moving bed adsorption tower; the solid adsorbent includes one or more of X - type zeolite, Y - type zeolite, and titanium - silicon molecular sieve.

[0025] The second aspect of the present disclosure provides a system for separating a liquid mixture by using the method described in the first aspect of the present disclosure. The system includes: a simulated moving bed adsorption device, an extract separation device, a raffinate separation device, an extract mixing device, and a raffinate mixing device;

[0026] The simulated moving bed adsorption device includes a raw material inlet, a desorbent inlet, an extract outlet, and a raffinate outlet;

[0027] The extract separation device includes a first desorbent outlet and a crude product outlet; the extract separation device is connected to the extract outlet through the extract mixing device;

[0028] The raffinate separation device includes a second desorbent outlet and a raffinate product outlet; the raffinate separation device is connected to the raffinate outlet through the raffinate mixing device.

[0029] Optionally, the first desorbent outlet and the second desorbent outlet are respectively connected to the desorbent inlet of the simulated moving bed adsorption device;

[0030] Optionally, the system further includes a fractionation device, which includes a crude product inlet and a target product outlet, and the crude product inlet is connected to the crude product outlet.

[0031] Through the above technical solution, the method for separating a liquid mixture according to the present disclosure sets the operating pressure of the feed point of the extract separation device to be appropriate, so that the sum of it and the pressure generated by the hydrostatic column height from the feed point to the extract mixing device is always higher than the bubble point pressure of the mixed material in the simulated moving bed adsorption device at the operating temperature; sets the operating pressure of the raffinate separation device feed point to be appropriate, so that the sum of it and the pressure generated by the hydrostatic column height from the feed point to the raffinate mixing device is always higher than the bubble point pressure of the mixed material in the simulated moving bed adsorption device at the operating temperature, and it will not cause the simulated moving bed adsorption device to lose pressure due to misoperation, thereby causing the mixed material to gasify and damage the internal components and solid adsorbents of the adsorption tower, enabling it to operate safely; on the one hand, it avoids the huge economic losses caused by the damage of the internal components and solid adsorbents after the simulated moving bed adsorption device loses pressure, on the other hand, it saves the complex process of setting up an emergency nitrogen replenishment system, saves the device investment, and at the same time avoids the economic losses caused by the shutdown of the device due to misoperation of the nitrogen replenishment system. At the same time, due to increasing the operating pressures of the extract separation device and the raffinate separation device, it is convenient to efficiently recover a large amount of condensation heat at the tops of the extract separation device and the raffinate separation device, and the energy consumption of the device can be significantly reduced.

[0032] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. Description of the Drawings

[0033] The drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification, and are used to explain the present disclosure together with the following specific implementation, but do not constitute a limitation to the present disclosure. In the drawings:

[0034] Figure 1 is a schematic process flow diagram of adsorptive separation of a liquid mixture in an embodiment of the present invention.

[0035] Description of the Reference Numerals in the Drawings

[0036] 1a - raw material, 1b - desorbent, 2 - simulated moving bed adsorption device, 3 - target product, 4a - extract, 4b - raffinate, 5 - extract separation device, 6 - raffinate separation device, 7 - extract mixing device, 8 - raffinate mixing device, 9 - raffinate product, 10 - crude product, 11 - fractionation device. Specific Embodiments

[0037] The following will describe in detail the specific embodiments of the present disclosure with reference to the drawings. It should be understood that the specific embodiments described herein are only for explaining and understanding the present disclosure, and are not used to limit the present disclosure.

[0038] As Figure 1 shown, the first aspect of the present disclosure provides a method for separating a liquid mixture, the method comprising:

[0039] S1. Contacting a mixed material containing feedstock 1a and desorbent 1b with a solid adsorbent in a simulated moving bed adsorption device 2 to perform liquid-liquid separation treatment, obtaining an extract 4a and a raffinate 4b;

[0040] S2. Passing the extract 4a obtained in step S1 through an extract mixing device 7 and then entering an extract separation device 5 to obtain a crude product 10 and desorbent 1b;

[0041] S3. Passing the raffinate 4b obtained in step S1 through a raffinate mixing device 8 and then entering a raffinate separation device 6 to obtain a raffinate product 9 and desorbent 1b;

[0042] wherein, P 4 +P 4 ’ > P 0 , P 5 +P 5 ’ > P 0 , P 2 > P 4 +P 4 , P 3 > P 5 +P 5 ’;

[0043] P 0 is the bubble point pressure of the mixed material at the first operating temperature of the simulated moving bed adsorption device 2;

[0044] P 2 is the second operating pressure of the extract mixing device 7;

[0045] P 3 is the third operating pressure of the raffinate mixing device 8;

[0046] P 4 is the fourth operating pressure at the feed point of the extract separation device 5;

[0047] P 4 ’ is the pressure generated by the static liquid column height between the feed point of the extract separation device 5 and the extract mixing device 7;

[0048] P 5 is the fifth operating pressure at the feed point of the raffinate separation device 6;

[0049] P 5 ’ is the pressure generated by the static liquid column height between the feed point of the raffinate separation device 6 and the raffinate mixing device 8;

[0050] Among them, the extract 4a is rich in the target product 3. In the present disclosure, the "pressure generated by the static liquid column height between the feed point of the extract separation device and the extract mixing device" refers to the pressure difference formed due to the different arrangement heights between the extract mixing device and the feed port of the extract separation device; the "pressure generated by the static liquid column height between the raffinate separation device feed point and the raffinate mixing device" refers to the pressure difference formed due to the different arrangement heights between the raffinate mixing device and the feed port of the raffinate separation device; the above pressures are proportional to the height and the feed density.

[0051] In the present disclosure, the separation of the liquid mixture is carried out by adsorption separation.

[0052] In one embodiment of the present disclosure, the raffinate 4b enters the raffinate separation device 6 by self-pressure, and the extract 4a enters the extract separation device 5 by self-pressure.

[0053] In one embodiment of the present disclosure, the raffinate product 9 enters the downstream facilities for utilization.

[0054] In one embodiment of the present disclosure, the method further includes: feeding the crude product 10 obtained in step S2 into a fractionation device 11 to obtain the target product 3. The separation device can be a fractionating tower.

[0055] In one embodiment of the present disclosure, the method further includes: respectively arranging heat recovery devices at the tops of the extract separation device 5, the raffinate separation device 6, and the fractionation device 11. The heat recovery device can be a steam generating device, and the generated steam is used for power generation or boosting into the pipe network or for heating; or it can be a hot water heat exchanger, and the hot water is used for refrigeration or as a heat source for other devices; or it can be a heat exchanger for other process materials, serving as a heat source for other equipment. The above heat recovery device can efficiently recover a large amount of condensation heat at the tops of the extract separation device, the raffinate separation device, and the fractionation device, and can greatly reduce the energy consumption of the device.

[0056] In one embodiment of the present disclosure, the simulated moving bed adsorption device 2 includes one or two adsorption towers, an adsorption tower circulation pump, an adsorption tower bed layer pipeline, and a device and a control system for switching the connection position of the adsorption tower bed layer pipeline and the interface of the simulated moving bed adsorption tower; the adsorption tower is filled with a solid adsorbent, a liquid phase material, and internal components; the solid adsorbent is filled in the adsorption tower in multiple layers and separated by internal components, which play a role in supporting the solid adsorbent and mixing and distributing the materials. The desorbent 1b includes one or more of toluene, methylcyclohexane, p - diethylbenzene, and n - nonane; the solid adsorbent includes one or more of X - type zeolite, Y - type zeolite, and titanium - silicon molecular sieve. The device and the control system for switching the connection position of the adsorption tower bed layer pipeline and the interface of the simulated moving bed adsorption tower are, for example, pipelines, valves, etc., and can be of conventional types in the art.

[0057] In an embodiment of the present disclosure, the first operating temperature of the simulated moving bed adsorption device 2 is 60 - 230 °C, and the first operating pressure is 0.6 - 2.8 MPaG; preferably, the first operating temperature is 60 - 185 °C, and the first operating pressure is 0.6 - 2.5 MPaG.

[0058] In the present disclosure, the bubble point pressure refers to: at the first operating temperature of the simulated moving bed adsorption device 2, as the pressure gradually decreases with the downward movement of the bed layer, the pressure when the first vapor bubble appears as the liquid material starts to vaporize.

[0059] In an embodiment of the present disclosure, the second operating temperature of the extract mixing device 7 is 60 - 230 °C, and the second operating pressure is 0.26 - 2.0 MPaG; preferably, the second operating temperature is 60 - 185 °C, the second operating pressure is 0.35 - 1.8 MPaG, and the second operating pressure is higher than the bubble point pressure of the mixed material at the first operating temperature. The extract mixing device 7 can be a mixing tank.

[0060] In an embodiment of the present disclosure, the third operating temperature of the raffinate mixing device 8 is 60 - 230 °C, and the third operating pressure is 0.26 - 2.0 MPaG; preferably, the third operating temperature is 60 - 185 °C, the third operating pressure is 0.35 - 1.8 MPaG, and the third operating pressure is higher than the bubble point pressure of the mixed material at the first operating temperature. The raffinate mixing device 8 can be a mixing tank.

[0061] In an embodiment of the present disclosure, the fourth operating temperature at the top of the extract separation device 5 is 80 - 220 °C, and the sixth operating pressure at the top of the extract separation device 5 is 0.2 - 1.5 MPaG; preferably, the fourth operating temperature is 80 - 200 °C, and the sixth operating pressure is 0.2 - 1.0 MPaG. The extract separation device 5 can be a fractionation tower system.

[0062] In an embodiment of the present disclosure, the fifth operating temperature at the top of the raffinate separation device 6 is 80 - 220 °C, and the seventh operating pressure at the top of the raffinate separation device 6 is 0.2 - 1.5 MPaG; preferably, the fifth operating temperature is 80 - 200 °C, and the seventh operating pressure is 0.2 - 1.0 MPaG. The raffinate separation device 6 can be a fractionation tower system.

[0063] In the present disclosure, the first operating pressure, the second operating pressure, the third operating pressure, the fourth operating pressure, the fifth operating pressure, the sixth operating pressure, and the seventh operating pressure are all gauge pressures.

[0064] In one embodiment of the present disclosure, the method further includes: returning the desorbent 1b separated from the extract separation device 5 and / or the raffinate separation device 6 to the simulated moving bed adsorption device 2 for continued use.

[0065] As Figure 1 shown, in a specific embodiment of the present disclosure, the method for adsorptive separation of a liquid mixture specifically includes: bringing a mixed material containing the raw material 1a and the desorbent 1b into contact with a solid adsorbent in the simulated moving bed adsorption device 2 for liquid-liquid separation treatment to obtain an extract 4a and a raffinate 4b; the simulated moving bed adsorption device 2 includes one or two adsorption towers, the desorbent 1b is any one of p-diethylbenzene, methylcyclohexane, toluene, and n-nonane, the solid adsorbent is X-type zeolite and / or Y-type zeolite, the first operating temperature of the simulated moving bed adsorption device 2 is 60-185°C, and the first operating pressure is 0.6-2.5 MPaG. The extract 4a enters the extract separation device 5 after passing through the extract mixing device 7 to obtain a crude product 10 and the desorbent 1b; the raffinate 4b enters the raffinate separation device 6 after passing through the raffinate mixing device 8 to obtain a raffinate product 9 and the desorbent 1b; the second operating temperature of the extract mixing device 7 is 60-185°C, the second operating pressure is 0.35-1.8 MPaG, the second operating pressure is higher than the bubble point pressure of the mixed material at the first operating temperature, and P 2 >P 4 +P 4 ’. The third operating temperature of the raffinate mixing device 8 is 60-185°C, the third operating pressure is 0.35-1.8 MPaG, the third operating pressure is higher than the bubble point pressure of the mixed material at the first operating temperature, and P 3 >P 5 +P 5 ’. The fourth operating temperature at the top of the extract separation device 5 is 80-200°C, the sixth operating pressure at the top of the extract separation device 5 is set to 0.2-1.0 MPaG, so that P 4 +P 4 ’>P 0 ; the fifth operating temperature at the top of the raffinate separation device 6 is 80-200°C, the seventh operating pressure at the top of the raffinate separation device 6 is set to 0.2-1.0 MPaG, so that P 5 +P 5 ’>P 0; The desorbent 1b separated from the extract separation device 5 and the raffinate separation device 6 is returned to the simulated moving bed adsorption device 2 for continued use; the crude product 10 is sent into the fractionation device 11 to obtain the target product 3. Specifically, taking the adsorption separation of p-xylene as an example, compared with the separation method in the prior art (an emergency nitrogen supplement device is provided, and when the pressure in the adsorption tower system is low to a certain value, the valve is opened to maintain the pressure of the adsorption tower system by supplementing nitrogen to the system), the present application omits the complex process of setting up an emergency nitrogen supplement system, saves the device investment, and at the same time avoids the economic losses caused by the shutdown of the device due to misoperation of the nitrogen supplement system.

[0066] The second aspect of the present disclosure provides a system for separating a liquid mixture by using the method of the first aspect of the present disclosure. The system includes: a simulated moving bed adsorption device 2, an extract separation device 5, a raffinate separation device 6, an extract mixing device 7, and a raffinate mixing device 8;

[0067] The simulated moving bed adsorption device 2 includes a raw material inlet, a desorbent inlet, an extract outlet, and a raffinate outlet; the raw material inlet is used to inject the raw material 1a into the simulated moving bed adsorption device 2, and the desorbent inlet is used to inject the desorbent 1b into the simulated moving bed adsorption device 2;

[0068] The extract separation device 5 includes a first desorbent outlet and a crude product outlet; the extract separation device 5 is connected to the extract outlet through the extract mixing device 7; and is used to make the extract 4a enter the extract separation device 5 from the simulated moving bed adsorption device 2;

[0069] The raffinate separation device 6 includes a second desorbent outlet and a raffinate product outlet; the raffinate separation device 6 is connected to the raffinate outlet through the raffinate mixing device 7; and is used to make the raffinate 4b enter the raffinate separation device 6 from the simulated moving bed adsorption device 2; the raffinate product outlet is used to discharge the produced raffinate product 9.

[0070] In an embodiment of the present disclosure, the system further includes a fractionation device 11. The fractionation device 11 includes a crude product inlet and a target product outlet. The crude product inlet is connected to the crude product outlet and is used to make the crude product enter the fractionation device 11 from the extract separation device 5; the target product outlet is used to discharge the target product.

[0071] In an embodiment of the present disclosure, the first desorbent outlet and the second desorbent outlet are respectively connected to the desorbent inlet, and are used to make the desorbent 1b separated from the extract separation device 5 and the raffinate separation device 6 enter the simulated moving bed adsorption device 2 for continued use.

[0072] In one embodiment of the present disclosure, the system further includes a heat recovery device respectively connected to the top of the extract separation device 5, the raffinate separation device 6, and the fractionation device 11, which is used to recover and utilize the heat generated by the system. This application can save 60 - 100 Kg of standard oil per ton of product.

[0073] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0074] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0075] Furthermore, any combination can be made among various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A method for separating a liquid mixture, characterized in that, the method comprises: S1. Contacting a mixed material containing a raw material (1a) and a desorbent (1b) with a solid adsorbent in a simulated moving bed adsorption device (2) to perform liquid-liquid separation treatment, obtaining an extract (4a) and a raffinate (4b); S2. Passing the extract (4a) obtained in step S1 through an extract mixing device (7) and then entering an extract separation device (5) to obtain a crude product (10) and a desorbent (1b); S3. Passing the raffinate (4b) obtained in step S1 through a raffinate mixing device (8) and then entering a raffinate separation device (6) to obtain a raffinate product (9) and a desorbent (1b); Among them, P 4 + P 4 ’ > P 0 , P 5 + P 5 ’ > P 0 , P 2 > P 4 + P 4 ’ , P 3 > P 5 + P 5 ’; P 0 is the bubble point pressure of the mixed material at the first operating temperature of the simulated moving bed adsorption device (2); P 2 is the second operating pressure of the extraction liquid mixing device (7); P 3 is the third operating pressure of the raffinate mixing device (8); P 4 is the fourth operating pressure at the feed point of the extract separation device (5); P 4 ’ is the pressure generated by the hydrostatic column height between the feed point of the extract separation device (5) and the extract mixing device (7); P 5 is the fifth operating pressure at the feed point of the raffinate separation device (6); P 5 ’ is the pressure generated by the hydrostatic head height between the feed point of the raffinate separation device (6) and the raffinate mixing device (8).

2. The method according to claim 1, wherein, the first operating temperature of the simulated moving bed adsorption device (2) is 60 - 230 °C, and the first operating pressure is 0.6 - 2.8 MPaG.

3. The method according to claim 1, wherein, the second operating temperature of the extract mixing device (7) is 60 - 230 °C, and the second operating pressure is 0.26 - 2.0 MPaG; and the second operating pressure is higher than the bubble point pressure of the mixed material at the first operating temperature.

4. The method according to claim 1, wherein, the third operating temperature of the raffinate mixing device (8) is 60 - 230 °C, and the third operating pressure is 0.26 - 2.0 MPaG; and the third operating pressure is higher than the bubble point pressure of the mixed material at the first operating temperature.

5. The method according to claim 1, wherein, the fourth operating temperature at the top of the extract separation device (5) is 80 - 220 °C; the sixth operating pressure at the top of the extract separation device (5) is 0.2 - 1.5 MPaG.

6. The method according to claim 1, wherein, the fifth operating temperature at the top of the raffinate separation device (6) is 80 - 220 °C; the seventh operating pressure at the top of the raffinate separation device (6) is 0.2 - 1.5 MPaG.

7. The method according to claim 1, wherein, the method further comprises: returning the desorbent (1b) separated from the extract separation device (5) and / or the raffinate separation device (6) to the simulated moving bed adsorption device (2) for continued use.

8. The method according to claim 1, wherein, the desorbent (1b) comprises one or more of toluene, methylcyclohexane, p - diethylbenzene, and n - nonane; the simulated moving bed adsorption device (2) comprises one or two simulated moving bed adsorption towers, an adsorption tower circulation pump, an adsorption tower bed layer pipeline, and a device and a control system for switching the communication position between the adsorption tower bed layer pipeline and the interface of the simulated moving bed adsorption tower; the solid adsorbent comprises one or more of X - type zeolite, Y - type zeolite, and titanium - silicon molecular sieve.

9. A system for separating a liquid mixture by using the method according to any one of claims 1 - 8, characterized in that, The system includes: a simulated moving bed adsorption device (2), an extract separation device (5), a raffinate separation device (6), an extract mixing device (7), and a raffinate mixing device (8); The simulated moving bed adsorption device (2) includes a raw material inlet, a desorbent inlet, an extract outlet, and a raffinate outlet; The extract separation device (5) includes a first desorbent outlet and a crude product outlet; the extract separation device (5) is connected to the extract outlet through the extract mixing device (7); The raffinate separation device (6) includes a second desorbent outlet and a raffinate product outlet; the raffinate separation device (6) is connected to the raffinate outlet through the raffinate mixing device (8).

10. The system according to claim 9, wherein, the first desorbent outlet and the second desorbent outlet are respectively connected to the desorbent inlet of the simulated moving bed adsorption device (2); Optionally, the system further includes a fractionation device (11), the fractionation device (11) includes a crude product inlet and a target product outlet, and the crude product inlet is connected to the crude product outlet.

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