A benzene recovery system and a styrene production system

Abstract

The utility model provides a kind of benzene recovery system and styrene production system.The benzene recovery system includes light component removal system, at least including light component removal tower, first condenser and first reflux tank;The feed inlet of light component removal tower is used to connect the source pipeline containing benzene and non-aromatic hydrocarbon gas;The top gas phase outlet of light component removal tower is connected with the import of first condenser, and the outlet of first condenser is connected with the import of first reflux tank;Extraction rectification system at least includes extraction rectification tower, stripping tower, second condenser and second reflux tank;The solvent import pipeline of extraction rectification tower is connected with extraction solvent pipeline, and the raw material import of extraction rectification tower is connected with the discharge pipeline of first reflux tank, the feed inlet of stripping tower is connected with the tower kettle liquid outlet of extraction rectification tower, the top steam outlet of stripping tower is connected with second condenser, the outlet of second condenser is connected with the import of second reflux tank, and the liquid phase outlet of second reflux tank is connected with second benzene extraction pipeline.

Description

Technical Field

[0001] This utility model belongs to the field of styrene production technology, and in particular relates to a benzene recovery system and a styrene production system. Background Technology

[0002] Currently, in the styrene production process using ethylbenzene dehydrogenation, the use of low-purity coking benzene (benzene content > 99.5%) has become an industry trend to further reduce raw material costs. The high content of non-aromatic hydrocarbons in low-purity coking benzene leads to the escape of high-content pure benzene (typically benzene content > 85%) during the benzene recovery process in the styrene-ethylbenzene unit cycle. Because existing separation processes struggle to achieve deep separation of non-aromatic hydrocarbons from benzene, this results in both a waste of benzene resources and increased subsequent environmental treatment costs. Utility Model Content

[0003] In view of the above-mentioned problems existing in the prior art, the purpose of this utility model embodiment is to provide a benzene recovery system and a styrene production system.

[0004] The technical solution adopted in this embodiment of the utility model is: A benzene recovery system, comprising: A light component removal system includes at least a light component removal tower, a first condenser, and a first reflux tank; the inlet of the light component removal tower is used to connect to a source pipeline containing at least benzene and non-aromatic hydrocarbons; the top gas phase outlet of the light component removal tower is connected to the inlet of the first condenser, the outlet of the first condenser is connected to the inlet of the first reflux tank, and the bottom liquid phase outlet of the light component removal tower is connected to a first benzene collection pipeline; An extractive distillation system includes at least an extractive distillation column, a stripping column, a second condenser, and a second reflux tank. The solvent inlet of the extractive distillation column is connected to an extraction solvent pipeline, the feed inlet of the extractive distillation column is connected to the discharge pipeline of the first reflux tank, the feed inlet of the stripping column is connected to the bottom liquid outlet of the extractive distillation column, the top vapor outlet of the stripping column is connected to the second condenser, the outlet of the second condenser is connected to the inlet of the second reflux tank, and the liquid phase outlet of the second reflux tank is connected to a second benzene collection pipeline.

[0005] In some embodiments, the extractive distillation system further includes a third condenser, a third reflux tank, and a first cooler; The vapor outlet at the top of the extractive distillation column is connected to the inlet of the third condenser, the outlet of the third condenser is connected to the inlet of the third reflux tank, the first outlet of the third reflux tank is connected to the reflux port of the extractive distillation column, the second outlet of the third reflux tank is connected to the inlet of the first cooler, and the outlet of the first cooler is connected to the non-aromatic hydrocarbon collection pipeline.

[0006] In some embodiments, the bottom of the extractive distillation column has a reboiler, and the first flow path of the reboiler is connected to the extractive distillation column; The extractive distillation system also includes a preheater and a second cooler; The preheater is located on the discharge pipeline of the first reflux tank, and the first process of the preheater is connected to the liquid phase outlet of the first reflux tank and the raw material inlet of the extractive distillation column. The second process of the reboiler is connected to the liquid phase outlet of the stripping column and the inlet of the second process of the preheater. The outlet of the second process of the preheater is connected to the inlet of the second cooler, and the outlet of the second cooler is connected to the solvent inlet of the extractive distillation column.

[0007] In some embodiments, the extractive distillation system further includes a first three-way valve, the first inlet of which is connected to the outlet of the second process of the preheater, the second inlet of which is connected to the second process of the reboiler, and the outlet of which is connected to the inlet of the second cooler.

[0008] In some embodiments, the extractive distillation system further includes a second three-way valve, wherein the first inlet of the second three-way valve is connected to the outlet of the first three-way valve, the second inlet of the second three-way valve is connected to the outlet of the second cooler, and the outlet of the second three-way valve is connected to the solvent inlet of the extractive distillation column.

[0009] In some embodiments, the light component removal system further includes a dechlorination tank and a fourth condenser, wherein the gas phase outlet of the first reflux tank is connected to the inlet of the dechlorination tank, the gas phase outlet of the dechlorination tank is connected to the inlet of the fourth condenser, and the outlet of the fourth condenser is connected to an aromatics recovery pipeline.

[0010] In some embodiments, the light component removal system further includes a non-aromatic hydrocarbon emergency tank, wherein the liquid phase outlet of the first reflux tank is connected to the non-aromatic hydrocarbon emergency tank.

[0011] In some embodiments, the benzene recovery system further includes: A vacuum system, comprising a vacuum pump, a solvent tank, and a third cooler; the inlet of the vacuum pump is connected to the liquid phase outlet of the third reflux tank, the outlet of the vacuum pump is connected to the inlet of the solvent tank, the first outlet of the solvent tank is connected to the inlet of the third cooler, the outlet of the third cooler is connected to the inlet of the vacuum pump, and the second outlet of the solvent tank is connected to the feed inlet of the stripping tower.

[0012] In some embodiments, the benzene recovery system further includes a solvent recovery system; The solvent recovery system includes a solvent regeneration tank and a solvent regeneration condenser; the inlet of the solvent regeneration tank is connected to the liquid phase outlet of the stripping tower, the outlet of the solvent regeneration tank is connected to the inlet of the solvent regeneration condenser, the gas phase outlet of the solvent regeneration condenser is connected to the inlet of the vacuum pump, and the liquid phase outlet of the solvent regeneration condenser is connected to the inlet of the third cooler.

[0013] A styrene production system, characterized in that it includes a benzene recovery system as described in any of the above embodiments.

[0014] Compared with the prior art, the beneficial effects of the embodiments of this utility model are as follows: The benzene recovery system in this embodiment achieves preliminary separation of a mixed gas containing benzene and non-aromatic hydrocarbons through a light component removal tower. Then, an extractive distillation tower is used to extract and distill the remaining mixed gas in the light component removal tower. This achieves extractive distillation of benzene and non-aromatic hydrocarbons, distillation separation of benzene and extractant, and production of high-purity benzene. It reduces the benzene content in non-aromatic hydrocarbons from 85% to below 10%, ensuring the efficient production of high-purity benzene, effectively recovering high-purity benzene from non-aromatic hydrocarbons, and reducing the benzene content in non-aromatic hydrocarbons.

[0015] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit the present invention.

[0016] The description of various implementations or examples of the technology in this utility model is an overview and not a full disclosure of the entire scope or all features of the disclosed technology. Attached Figure Description

[0017] In drawings that are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The drawings generally illustrate various embodiments by way of example rather than limitation and, together with the description and claims, serve to explain embodiments of the utility model. Where appropriate, the same reference numerals are used in all drawings to refer to the same or similar parts.

[0018] Figure 1 This is a schematic diagram of the benzene recovery system according to an embodiment of the present invention.

[0019] In the picture: 1. Light component removal system; 10. Light component removal tower; 11. First reflux tank; 12. First condenser; 13. Dechlorination tank; 14. Fourth condenser; 15. Non-aromatic hydrocarbon emergency tank; 16. Source pipeline; 17. First benzene extraction pipeline; 18. First non-aromatic hydrocarbon extraction pipeline; 19. Discharge pipeline; 2. Extractive distillation system; 20. Extractive distillation column; 21. Stripping column; 22. Second condenser; 23. Second reflux tank; 231. Second benzene extraction pipeline; 24. Third condenser; 25. Third reflux tank; 26. First cooler; 261. Second non-aromatic hydrocarbon extraction pipeline; 27. Reboiler; 28. Preheater; 29. ​​Second cooler; 291. Second three-way valve; 292. First three-way valve; 3. Vacuum system; 31. Solvent tank; 32. Solvent pump; 33. Tertiary cooler; 34. Vacuum pump; 4. Solvent recovery system; 41. Solvent regeneration tank; 42. Solvent regeneration condenser. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0021] Unless otherwise defined, the technical or scientific terms used in this utility model shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar words used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly. To keep the following description of the embodiments of this utility model clear and concise, detailed descriptions of known functions and known components are omitted.

[0022] like Figure 1 As shown in the figure, this utility model embodiment provides a benzene recovery system, which includes at least a light component removal system 1 and an extractive distillation system 2. The benzene recovery system includes at least a light component removal tower 10, a first condenser 12, and a first reflux tank 11.

[0023] The feed inlet of the light component removal tower 10 is used to connect to the source line 16 containing benzene and non-aromatic gases. The source line 16 can be the non-condensable vapor outlet line of the ethylbenzene unit system.

[0024] The light component removal column 10 is used to perform preliminary distillation separation by utilizing the limited boiling point difference between benzene and non-aromatic hydrocarbons, to separate the material in the source pipeline 16 into overhead product and bottom product. The overhead product is a mixture rich in light non-aromatic hydrocarbons (such as cyclohexane, olefins, etc.) but still contains a high concentration of benzene; the bottom product is a material with high benzene purity. The light component removal column 10 can be a distillation column.

[0025] The vapor outlet at the top of the light component removal column 10 is connected to the inlet of the first condenser 12. The first reflux tank 11 has an inlet and a liquid outlet, and the outlet of the first condenser 12 is connected to the inlet of the first reflux tank 11. The liquid outlet of the first reflux tank 11 is connected to both the reflux port of the light component removal column 10 and the extractive distillation system 2.

[0026] The product at the top of the light component removal tower 10 enters the first condenser 12 through the top gas phase outlet and is condensed into liquid, then sent to the first reflux tank 11 for gas-liquid separation. Part of the separated liquid phase is returned to the light component removal tower 10 through the reflux port for reflux, while the other part is sent to the extractive distillation system 2 as an intermediate product, which is a non-aromatic mixture with a high benzene content.

[0027] The bottom liquid outlet of the light component removal tower 10 is connected to the first benzene extraction pipeline 17. The bottom product in the light component removal tower 10 is sent out through the first benzene extraction pipeline 17 for recycling.

[0028] The extractive distillation system 2 includes at least an extractive distillation column 20, a stripping column 21, a second condenser 22, and a second reflux tank 23. The extractive distillation column 20 mainly injects an extractant into the column to change the relative volatility of benzene and non-aromatic hydrocarbons, and separates a low-benzene non-aromatic hydrocarbon mixture and a mixture of benzene and the extraction solvent.

[0029] The extractant can be N-formylmorpholine or sulfolane, etc. The low-benzene non-aromatic mixture is discharged through the top steam outlet of the tower, and the mixture of benzene and the extraction solvent is discharged through the bottom liquid outlet of the tower.

[0030] In this embodiment, the solvent inlet of the extractive distillation column 20 can be connected to an extractive solvent pipeline, through which the extractant can be added into the extractive distillation column 20. The extractive solvent pipeline can be a separate pipeline for adding the extractant into the extractive distillation column 20, or it can be a pipeline connecting the solvent inlet of the extractive distillation column 20 to the liquid phase outlet of the stripping column.

[0031] The feed inlet of the extractive distillation column 20 is connected to the discharge line 19 of the first reflux tank 11. The liquid phase separated in the first reflux tank 11 (i.e. the intermediate product mentioned above) is sent into the extractive distillation column 20 through the discharge line 19.

[0032] The feed inlet of stripping tower 21 is connected to the bottom liquid outlet of extractive distillation tower 20, the top vapor outlet of stripping tower 21 is connected to the second condenser 22, the outlet of the second condenser 22 is connected to the inlet of the second reflux tank 23, and the liquid phase outlet of the second reflux tank 23 is connected to the second benzene production pipeline 231 and the reflux port of stripping tower 21.

[0033] Stripping column 21 is mainly used to distill the mixture of benzene and extraction solvent discharged from extractive distillation column 20 to obtain high-purity benzene vapor and extraction solvent with extremely low benzene content. The high-purity benzene vapor is discharged through the top vapor outlet of the column, while the extraction solvent with extremely low benzene content is discharged through the bottom liquid outlet of stripping column 21 at a higher temperature.

[0034] Furthermore, high-purity benzene vapor is discharged through the top steam outlet of the tower into the second condenser 22 for condensation to form condensate. The main components of this condensate are liquid benzene and trace amounts of non-condensable vapor. The condensate flows into the second reflux tank 23 for gas-liquid separation. Part of the separated liquid benzene is returned to the top of the stripping tower 21 through the reflux port, while the other part is continuously and stably extracted as the final product through the second benzene extraction pipeline and sent to the product storage tank or downstream processes.

[0035] The benzene recovery system in this embodiment achieves preliminary separation of a mixed gas containing benzene and non-aromatic hydrocarbons through a light component removal tower 10. Then, the unseparated mixed gas in the light component removal tower 10 is extracted and distilled using an extractive distillation tower 20. This achieves extractive distillation of benzene and non-aromatic hydrocarbons, distillation separation of benzene and extractant, and the production of high-purity benzene. It reduces the benzene content in non-aromatic hydrocarbons from 85% to below 10%, ensuring the efficient production of high-purity benzene, effectively recovering high-purity benzene from non-aromatic hydrocarbons, and reducing the benzene content in non-aromatic hydrocarbons.

[0036] In some embodiments, the light component removal system 1 may further include a dechlorination tank 13 and a fourth condenser 22. The first reflux tank 11 may include a gas phase outlet, which may be connected to the inlet of the dechlorination tank 13. The gas phase separated in the first reflux tank 11 contains toxic substances such as chlorinated hydrocarbons. Sending this gas phase into the dechlorination tank 13 can remove chloride impurities that may be present in the non-condensable gas, particularly chlorinated hydrocarbons (such as chloromethane and chlorobenzene). These impurities originate from low-purity coking benzene and are byproducts of the coking process.

[0037] The gas phase outlet of the dechlorination tank 13 can be connected to the inlet of the fourth condenser 14, and the outlet of the fourth condenser 14 can be connected to the non-aromatic hydrocarbon extraction pipeline 18. The fourth condenser 14 is used to deeply cool the gas containing oxygen, CO2 and other components after dechlorination, thereby recovering the remaining non-aromatic hydrocarbons, which are then output through the first non-aromatic hydrocarbon extraction pipeline 18.

[0038] In some embodiments, the light component removal system 1 may further include a non-aromatic hydrocarbon emergency tank 15, and the liquid phase outlet of the first reflux tank 11 may also be connected to the non-aromatic hydrocarbon emergency tank 15. When the recovery system malfunctions, non-conforming non-aromatic hydrocarbons can be stored in the non-aromatic hydrocarbon emergency tank 15 to prevent them from impacting and contaminating the subsequent precision extractive distillation system 2.

[0039] like Figure 1 As shown, in some embodiments, the extractive distillation system 2 may further include a third condenser 24, a third reflux tank 25, and a first cooler 26.

[0040] The vapor outlet at the top of the extractive distillation column 20 is connected to the inlet of the third condenser 24. The outlet of the third condenser 24 is connected to the inlet of the third reflux tank 25. The first outlet of the third reflux tank 25 is connected to the reflux port of the extractive distillation column 20. The second outlet of the third reflux tank 25 is connected to the inlet of the first cooler 26. The outlet of the first cooler 26 is connected to the non-aromatic hydrocarbon collection line 261. In the extractive distillation column, by controlling a certain ratio of extraction solvent to feed, the extractive distillation of pure benzene is completed, separating non-aromatic hydrocarbons with a benzene content of less than 10%. These non-aromatic hydrocarbons enter the third condenser 24 for condensation and then enter the third reflux tank 25. A portion of the liquid phase discharged from the third reflux tank 25 flows back to the reflux port of the extractive distillation column 20, while the other portion flows into the first cooler 26 for cooling and is finally discharged through the second non-aromatic hydrocarbon collection line 261.

[0041] In some embodiments, the bottom of the extractive distillation column 20 has a reboiler 27. The first flow path of the reboiler 27 is connected to the bottom of the extractive distillation column 20, and it is used to heat the liquid at the bottom of the column, causing it to partially vaporize. This rising vapor is the sole driving force for heat and mass transfer within the distillation column. An external heat source can flow through the first flow path of the reboiler 27, and the bottom of the extractive distillation column 20 can be heated by the external heat source. The first choice of external heat source is the waste heat of the high-temperature material in the bottom of the stripping column 21, or it can be steam or hot oil, etc.

[0042] In this embodiment, the extractive distillation system 2 may further include a preheater 28 and a second cooler 29. Both the preheater 28 and the reboiler 27 may be heat exchangers.

[0043] Both the preheater 28 and the reboiler 27 include two mutually exchanging heat flows: a first flow and a second flow. The first flow can be either the shell side or the tube side, and the second flow can be either the shell side or the tube side.

[0044] The preheater 28 can be installed on the discharge line 19 of the first reflux tank 11. The first process of the preheater 28 is connected to the liquid phase outlet of the first reflux tank 11 and the raw material inlet of the extractive distillation column 20. The second process of the reboiler 27 is connected to the bottom liquid phase outlet of the stripping column 21 and the inlet of the second process of the preheater 28.

[0045] The extraction solvent, with extremely low benzene content and a relatively high temperature, exits from the bottom liquid outlet of stripping column 21 and can be directly discharged into the second flow of reboiler 27 to release heat, thereby heating the external heat source flowing in the first flow of reboiler 27. The extracted solvent, after releasing heat, can then flow back into the second flow of preheater 28 to heat the material entering extractive distillation column 20, ensuring that the material reaches a suitable inlet temperature. The combination of reboiler 27 and preheater 28 achieves efficient utilization of solvent heat.

[0046] Continuing with this embodiment, the outlet of the second process of the preheater 28 is connected to the inlet of the second cooler 29, and the outlet of the second cooler 29 is connected to the solvent inlet of the extractive distillation column 20. The second cooler 29 is located downstream of the preheater 28 and is used to perform final temperature fine-tuning on the solvent entering the column, ensuring that it enters the top of the extractive distillation column 20 at a precise temperature.

[0047] In some embodiments, the extractive distillation system 2 may further include a first three-way valve 292. The first inlet of the first three-way valve 292 is connected to the outlet of the second process of the preheater 28, the second inlet of the first three-way valve 292 is connected to the outlet of the second process of the reboiler 27, and the outlet of the first three-way valve 292 is connected to the inlet of the second cooler 29.

[0048] The first three-way valve 292 allows the extraction solvent, after releasing heat from the reboiler 27, to enter the preheater 28 to heat the material entering the extractive distillation column 20. Alternatively, it can bypass the preheater 28; the temperature of the extractant in this bypass route remains relatively unchanged. Finally, these two routes are remixed after the first three-way valve 292 or in a downstream pipeline. By adjusting the flow ratio of these two routes, the temperature of the mixed extractant can be well controlled. In some embodiments, the extractive distillation system 2 may further include a second three-way valve 291. The first inlet of the second three-way valve 291 is connected to the outlet of the first three-way valve 292, the second inlet of the second three-way valve 291 is connected to the outlet of the second cooler 29, and the outlet of the second three-way valve 291 is connected to the solvent inlet of the extractive distillation column 20. The principle of the second three-way valve 291 is similar to that of the first three-way valve 292. Part of the extractant flowing out of the first three-way valve 292 flows into the second cooler 29 for cooling, while the other part bypasses the second cooler 29 and mixes with the cooled extractant, thereby precisely controlling the temperature of the extractant entering the extractive distillation column 20.

[0049] like Figure 1 As shown, the benzene recovery system may also include a vacuum pump 34, a solvent tank 31, and a third cooler 33. The inlet of the vacuum pump 34 is connected to the gas phase outlet of the third reflux tank 25, and the outlet of the vacuum pump 34 is connected to the inlet of the solvent tank 31. The vacuum pump 34 is used to draw in the non-condensable gases and entrained solvent vapors accumulated in the third reflux tank 25 and transport them into the third reflux tank 25. In the solvent tank 31, most of the solvent vapors are condensed into liquid and separated from the non-condensable gases, thus achieving primary solvent recovery. Simultaneously, this setup can provide negative pressure conditions for the stripping system and also enable the recovery and reuse of gaseous solvents.

[0050] The second outlet of solvent tank 31 is connected to the feed inlet of stripping tower 21 via solvent pump 32. The solvent stored in solvent tank 31 is at a relatively low temperature. The solvent pump 32 transports the cooled solvent back to the upper middle part of stripping tower 21 to precisely control the temperature distribution of the rectification section of stripping tower 21 and optimize the separation effect.

[0051] Furthermore, the first outlet of the solvent tank 31 is connected to the inlet of the third cooler 33; the outlet of the third cooler 33 is connected to the inlet of the vacuum pump 34. By drawing out a stream of cold liquid solvent from the first outlet of the solvent tank 31, further cooling it through the cooler, and then injecting it into the inlet line of the vacuum pump 34, the power required for the vacuum pump 34 to compress the gas is reduced, directly saving electricity consumption.

[0052] In some embodiments, the benzene recovery system may further include a solvent recovery system 4. The solvent recovery system 4 may include a solvent regeneration tank 41 and a solvent regeneration condenser 42.

[0053] The inlet of the solvent regeneration tank 41 is connected to the liquid phase outlet of the stripping tower 21, the outlet of the solvent regeneration tank 41 is connected to the inlet of the solvent regeneration condenser 42, the gas phase outlet of the solvent regeneration condenser 42 is connected to the inlet of the vacuum pump 34, and the liquid phase outlet of the solvent regeneration condenser 42 is connected to the inlet of the third cooler 33.

[0054] A portion of the high-temperature extractant discharged from the liquid outlet of the stripping tower 21 can enter the solvent regeneration tank 41. The heavy component impurities (such as polymers and tar-like substances) precipitated in the solvent regeneration tank 41 can be discharged through the slag discharge line, while the useful light components (such as solvent and benzene) evaporated in the solvent regeneration tank 41 enter the solvent regeneration condenser 42 for condensation.

[0055] The trace amounts of non-condensable waste gas (such as air, light decomposition gas) in the solvent regeneration condenser 42 are introduced into the vacuum pump 34 through the gas phase outlet and are eventually drawn away and treated. The clean solvent (which may contain a small amount of benzene) recovered by condensation in the solvent regeneration condenser 42 is then sent to the solvent tank 31 or the third cooler 33 to achieve a closed-loop material system.

[0056] In some embodiments, the light component removal tower 10, extractive distillation tower 20, stripping tower 21, multiple reflux tanks and non-aromatic hydrocarbon emergency tank 15 in the benzene recovery system may be equipped with level gauges for detecting the internal liquid level, so as to monitor the liquid level in the tank in real time and ensure the safe and stable operation of the entire system.

[0057] Additionally, measuring elements for detecting internal temperature and pressure can be installed separately. These measuring elements can monitor the temperature and pressure changes of the light component removal tower 10, extractive distillation tower 20, stripping tower 21, multiple reflux tanks, and non-aromatic hydrocarbon emergency tank 15 in real time, thereby promptly detecting and handling abnormal situations, further improving the safety and reliability of the entire system.

[0058] This utility model embodiment also provides a styrene production system, which may include a benzene recovery system as described in any of the above embodiments.

[0059] The above description is intended to be illustrative and not restrictive. Those skilled in the art can make variations, modifications, substitutions, and alterations to the above embodiments within the scope of this disclosure. Moreover, the above examples (or one or more of them) can be used in combination with each other, and these embodiments can be combined with each other in various combinations or arrangements.

Claims

1. A benzene recovery system, characterized in that, include: The light component removal system includes at least a light component removal tower, a first condenser, and a first reflux tank; The feed inlet of the light component removal tower is used to connect to a source pipeline containing at least benzene and non-aromatic hydrocarbons; the top gas phase outlet of the light component removal tower is connected to the inlet of the first condenser, the outlet of the first condenser is connected to the inlet of the first reflux tank, and the bottom liquid phase outlet of the light component removal tower is connected to the first benzene collection pipeline. An extractive distillation system includes at least an extractive distillation column, a stripping column, a second condenser, and a second reflux tank. The solvent inlet of the extractive distillation column is connected to an extraction solvent pipeline, the feed inlet of the extractive distillation column is connected to the discharge pipeline of the first reflux tank, the feed inlet of the stripping column is connected to the bottom liquid outlet of the extractive distillation column, the top vapor outlet of the stripping column is connected to the second condenser, the outlet of the second condenser is connected to the inlet of the second reflux tank, and the liquid phase outlet of the second reflux tank is connected to a second benzene collection pipeline.

2. The benzene recovery system as described in claim 1, characterized in that, The extractive distillation system also includes a third condenser, a third reflux tank, and a first cooler; The vapor outlet at the top of the extractive distillation column is connected to the inlet of the third condenser, the outlet of the third condenser is connected to the inlet of the third reflux tank, the first outlet of the third reflux tank is connected to the reflux port of the extractive distillation column, the second outlet of the third reflux tank is connected to the inlet of the first cooler, and the outlet of the first cooler is connected to the non-aromatic hydrocarbon collection pipeline.

3. The benzene recovery system as described in claim 1, characterized in that, The extractive distillation column has a reboiler at the bottom, and the first flow path of the reboiler is connected to the extractive distillation column. The extractive distillation system also includes a preheater and a second cooler; The preheater is located on the discharge pipeline of the first reflux tank, and the first process of the preheater is connected to the liquid phase outlet of the first reflux tank and the raw material inlet of the extractive distillation column. The second process of the reboiler is connected to the liquid phase outlet of the stripping column and the inlet of the second process of the preheater. The outlet of the second process of the preheater is connected to the inlet of the second cooler, and the outlet of the second cooler is connected to the solvent inlet of the extractive distillation column.

4. The benzene recovery system as described in claim 3, characterized in that, The extractive distillation system further includes a first three-way valve, the first inlet of which is connected to the outlet of the second process of the preheater, the second inlet of which is connected to the second process of the reboiler, and the outlet of which is connected to the inlet of the second cooler.

5. The benzene recovery system as described in claim 4, characterized in that, The extractive distillation system further includes a second three-way valve, the first inlet of which is connected to the outlet of the first three-way valve, the second inlet of which is connected to the outlet of the second cooler, and the outlet of the second three-way valve is connected to the solvent inlet of the extractive distillation column.

6. The benzene recovery system as described in claim 1, characterized in that, The light component removal system also includes a dechlorination tank and a fourth condenser. The gas phase outlet of the first reflux tank is connected to the inlet of the dechlorination tank, the gas phase outlet of the dechlorination tank is connected to the inlet of the fourth condenser, and the outlet of the fourth condenser is connected to the aromatics recovery pipeline.

7. The benzene recovery system as described in claim 1, characterized in that, The light component removal system also includes a non-aromatic hydrocarbon emergency tank, and the liquid phase outlet of the first reflux tank is connected to the non-aromatic hydrocarbon emergency tank.

8. The benzene recovery system as described in claim 1, characterized in that, The benzene recovery system also includes: A vacuum system, comprising a vacuum pump, a solvent tank, and a third cooler; the inlet of the vacuum pump is connected to the liquid phase outlet of the third reflux tank, the outlet of the vacuum pump is connected to the inlet of the solvent tank, the first outlet of the solvent tank is connected to the inlet of the third cooler, the outlet of the third cooler is connected to the inlet of the vacuum pump, and the second outlet of the solvent tank is connected to the feed inlet of the stripping tower.

9. The benzene recovery system as described in claim 8, characterized in that, The benzene recovery system also includes a solvent recovery system; The solvent recovery system includes a solvent regeneration tank and a solvent regeneration condenser; the inlet of the solvent regeneration tank is connected to the liquid phase outlet of the stripping tower, the outlet of the solvent regeneration tank is connected to the inlet of the solvent regeneration condenser, the gas phase outlet of the solvent regeneration condenser is connected to the inlet of the vacuum pump, and the liquid phase outlet of the solvent regeneration condenser is connected to the inlet of the third cooler.

10. A styrene production system, characterized in that, The benzene recovery system includes any one of claims 1-9.

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