Apparatus and method for separating aromatics from non-aromatics by liquid-liquid extraction

Abstract

The application relates to the technical field of aromatic hydrocarbon extraction, and discloses a device and a method for separating aromatic hydrocarbons from non-aromatic hydrocarbons through liquid-liquid extraction. The device comprises a liquid-liquid extraction tower, a non-aromatic hydrocarbon stripping tower, a raffinate water washing tower, a solvent recovery tower, a water stripping tower, a solvent regeneration tower, a non-aromatic hydrocarbon stripping tower kettle reboiler, a lean solvent / extract heat exchanger, a water stripping tower kettle reboiler and a heat balancer. The cold side inlet of the heat balancer is communicated with the first outlet of the bottom tray of the non-aromatic hydrocarbon stripping tower, the cold side outlet of the heat balancer is communicated with the first inlet of the kettle of the non-aromatic hydrocarbon stripping tower and / or the cold side inlet of the non-aromatic hydrocarbon stripping tower kettle reboiler, the hot side inlet of the heat balancer is communicated with the lean solvent outlet at the bottom of the solvent recovery tower, and the hot side outlet of the heat balancer is sequentially communicated with the hot side of the water stripping tower kettle reboiler, the hot side of the lean solvent / extract heat exchanger and the top tray of the liquid-liquid extraction tower. The device can realize efficient balancing of heat.

Description

Technical Field

[0001] This invention relates to the technical field of aromatic hydrocarbon extraction, and specifically to an apparatus and method for separating aromatic hydrocarbons and non-aromatic hydrocarbons by liquid-liquid extraction. Background Technology

[0002] Aromatic hydrocarbon liquid-liquid extraction is a physical separation method. When the solvent and the extraction feed are subjected to liquid-liquid contact extraction in the extraction tower, the solvent selectively dissolves the aromatic hydrocarbons and non-aromatic hydrocarbons in the feed, thereby forming two phases with different compositions and densities. The heavier phase mainly contains the solvent and aromatic hydrocarbons, while the lighter phase mainly contains non-aromatic hydrocarbons. Through multiple mass transfers in the tower, the aromatic hydrocarbons and non-aromatic hydrocarbons are separated.

[0003] The aromatic hydrocarbon liquid-liquid extraction system mainly includes six tower systems: liquid-liquid extraction tower, non-aromatic hydrocarbon stripping tower, extraction residue washing tower, solvent recovery tower, water stripping tower, and solvent regeneration tower.

[0004] The water in the extraction system circulates throughout the entire extraction system, forming a water circulation system. The water in the water circulation system has two main uses:

[0005] 1. As stripping steam for the solvent recovery tower, ensure that the solvent recovery tower has sufficient stripping steam to control the content of aromatics entrained in the solvent.

[0006] 2. The water used as washing water in the extraction residue washing tower meets the water volume required for washing the extraction residue, ensuring that the solvent loss of non-aromatic products meets the requirements.

[0007] The two purposes mentioned above are primarily to ensure the required amount of stripping steam for the solvent recovery tower. For ease of comparison, the circulating water volume of the water system is defined as the washing water volume of the extraction residue washing tower. The water volume in the circulating system is directly proportional to energy consumption. The heat source for the stripping steam comes from the heat of the circulating lean solvent. The challenge lies in achieving a precise match between the waste heat of the lean solvent and the water volume in the circulating system, minimizing the water volume while efficiently utilizing the waste heat of the lean solvent, ultimately achieving a high-efficiency heat balance for the entire extraction unit.

[0008] US patent application US05432347A discloses a method for separating aromatics by liquid-liquid extraction. This method includes an extraction tower, a stripping tower, and a recovery tower. The extracted feedstock is contacted countercurrently with a solvent in the extraction tower. The extract enters the stripping tower to obtain stripped non-aromatics and a solvent-rich solution. The stripped non-aromatics are condensed and returned to the bottom of the extraction tower as wash liquid. This method does not achieve efficient heat balance in the apparatus.

[0009] US Patent Application US06185102A discloses a method for recovering aromatics from a mixture. Solvent extraction yields a non-aromatic residue and a solvent-rich aromatic extract; the aromatic extract is passed through a stripping column to remove non-aromatics; the overhead condensate is collected at the top of the stripping column and returned to the extraction column as reflux wash. This method does not achieve efficient heat balance in the apparatus.

[0010] In summary, none of the existing methods for separating aromatic and non-aromatic hydrocarbons by liquid-liquid extraction have achieved efficient heat balance in the apparatus. Summary of the Invention

[0011] The purpose of this invention is to overcome the problem that existing liquid-liquid extraction devices for separating aromatic and non-aromatic hydrocarbons cannot achieve efficient heat balance, and to provide a device and method for liquid-liquid extraction separation of aromatic and non-aromatic hydrocarbons that can achieve efficient heat balance.

[0012] To achieve the above objectives, the first aspect of the present invention provides an apparatus for liquid-liquid extraction to separate aromatic hydrocarbons and non-aromatic hydrocarbons, wherein the apparatus comprises a liquid-liquid extraction tower, a non-aromatic hydrocarbon stripping tower, a raffinate washing tower, a solvent recovery tower, a water stripping tower, a solvent regeneration tower, a non-aromatic hydrocarbon stripping tower reboiler, a lean solvent / raffinate heat exchanger, a water stripping tower reboiler, and a heat balancer, all interconnected.

[0013] The cold-side inlet of the heat balancer is connected to the first outlet of the bottom tray of the non-aromatic stripper, and the cold-side outlet of the heat balancer is connected to the first inlet of the bottom of the non-aromatic stripper and / or the cold-side inlet of the reboiler of the non-aromatic stripper.

[0014] The hot-side inlet of the heat balancer is connected to the lean solvent outlet at the bottom of the solvent recovery tower, and the hot-side outlet of the heat balancer is connected in sequence to the hot side of the reboiler of the water stripping tower, the hot side of the lean solvent / extract heat exchanger, and the top tray of the liquid-liquid extraction tower.

[0015] Preferably, the hot-side inlet of the lean solvent / extract heat exchanger is connected to the hot-side outlet of the water stripping column reboiler, and the hot-side outlet of the lean solvent / extract heat exchanger is connected to the top tray of the liquid-liquid extraction column.

[0016] A second aspect of the present invention provides a method for separating aromatic hydrocarbons and non-aromatic hydrocarbons by liquid-liquid extraction, wherein the method is carried out in the apparatus described in the first aspect.

[0017] The device provided by this invention achieves precise matching between the waste heat of lean solvent and the water volume of the water circulation system by setting up a heat balancer, while ensuring the required amount of stripping steam in the solvent recovery tower and the amount of washing water in the extraction residue washing tower.

[0018] The device provided by this invention, by setting up a heat balancer, ensures the required amount of stripping steam for the solvent recovery tower and the amount of washing water for the extraction residue washing tower, while minimizing the water volume of the water circulation system and achieving efficient utilization of waste heat from lean solvent, ultimately achieving efficient heat balance for the entire device.

[0019] The device provided by this invention, by setting up a heat balancer, achieves flexible adjustment of the circulating water volume of the water system while ensuring the required stripping steam volume of the solvent recovery tower and the washing water volume of the extraction residue washing tower. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the device in Embodiment 1 of the present invention;

[0021] Figure 2 This is a schematic diagram of the device in Embodiment 2 of the present invention;

[0022] Figure 3 This is a schematic diagram of the device in Embodiment 3 of the present invention;

[0023] Figure 4 This is a schematic diagram of the apparatus in Comparative Examples 1-3 of the present invention.

[0024] Explanation of reference numerals in the attached figures

[0025] 1-Liquid-liquid extraction tower; 2-Non-aromatic stripping tower;

[0026] 3-Water washing tower for extraction residue; 4-Solvent recovery tower;

[0027] 5-Water stripping tower; 6-Solvent regeneration tower;

[0028] 7-Residue cooler; 8-Lean solvent / extract heat exchanger;

[0029] 9-Non-aromatic stripping tower overhead cooler; 10-Non-aromatic stripping tower overhead collection tank;

[0030] 11- Solvent recovery tower top cooler; 12- Solvent recovery tower top reflux tank;

[0031] 13-Reboiler for non-aromatic stripping tower; 14-Reboiler for solvent recovery tower;

[0032] 15-Reboiler in the solvent regeneration tower; 16-Reboiler in the water stripping tower;

[0033] 17-Stripping water cooler; 18-Stay-at-home heat balancer;

[0034] 19-Thermosiphon type heat balancer; 20-Shell-tube type heat balancer;

[0035] 21-Hydrocarbon mixtures; 22-Rain residue;

[0036] 23-Extractant; 24-Stripped non-aromatic hydrocarbons;

[0037] 25-Wash solution; 26-Water-in-water collection tank at the top of the non-aromatic stripping tower;

[0038] 27-Rich solvent; 28-Aromatic products;

[0039] 29 - Water-in-water reflux tank at the top of the solvent recovery tower; 30 - Lean solvent;

[0040] 31 - Solvent to be regenerated; 32 - Regenerated solvent;

[0041] 33-Waste solvent; 34-Non-aromatic hydrocarbons;

[0042] 35-Wash water containing solvent; 36-Stripping water;

[0043] 37-Stripping steam; 38-Recovered solvent;

[0044] 39 - Hot side inlet of the reboiler in the steam stripper; 40 - Hot side outlet of the reboiler in the steam stripper; 41 - Extraction solvent; 42 - Hot side inlet of the heat balancer. Detailed Implementation

[0045] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0046] In this invention, it should be noted that the circulating water volume of the water system is based on the water volume of the extraction residue washing tower (water in the reflux tank at the top of the solvent recovery tower).

[0047] The first aspect of the present invention provides an apparatus for separating aromatic hydrocarbons and non-aromatic hydrocarbons by liquid-liquid extraction, wherein the apparatus comprises a liquid-liquid extraction tower 1, a non-aromatic hydrocarbon stripping tower 2, a raffinate washing tower 3, a solvent recovery tower 4, a water stripping tower 5, a solvent regeneration tower 6, a non-aromatic hydrocarbon stripping tower reboiler 13, a lean solvent / raffinate heat exchanger 8, a water stripping tower reboiler 16, and a heat balancer.

[0048] The cold-side inlet of the heat balancer is connected to the first outlet of the bottom tray of the non-aromatic stripping tower 2, and the cold-side outlet of the heat balancer is connected to the first inlet of the bottom of the non-aromatic stripping tower 2 and / or the cold-side inlet of the reboiler 13 of the non-aromatic stripping tower.

[0049] The hot-side inlet 42 of the heat balancer is connected to the lean solvent outlet at the bottom of the solvent recovery tower 4, and the hot-side outlet of the heat balancer is connected in sequence to the hot side of the water stripping tower reboiler 16, the hot side of the lean solvent / extract heat exchanger 8, and the top tray of the liquid-liquid extraction tower 1.

[0050] The device provided by this invention achieves precise matching between the waste heat of lean solvent and the water volume of the water circulation system by setting up a heat balancer, while ensuring the required amount of stripping steam in the solvent recovery tower and the amount of washing water in the extraction residue washing tower.

[0051] The device provided by this invention, by setting up a heat balancer, ensures the required amount of stripping steam for the solvent recovery tower and the amount of washing water for the extraction residue washing tower, while minimizing the water volume of the water circulation system and achieving efficient utilization of waste heat from lean solvent, ultimately achieving efficient heat balance for the entire device.

[0052] The device provided by this invention, by setting up a heat balancer, achieves flexible adjustment of the circulating water volume of the water system while ensuring the required stripping steam volume of the solvent recovery tower and the washing water volume of the extraction residue washing tower.

[0053] In this invention, preferably, the liquid-liquid extraction tower 1 is provided with a residue discharge pipeline at the top of the tower, and the liquid-liquid extraction tower 1 is connected to the bottom tray of the residue washing tower 3 through the residue discharge pipeline.

[0054] In this invention, preferably, an extraction residue cooler 7 is provided on the extraction residue discharge pipeline. The inlet of the extraction residue cooler 7 is connected to the extraction residue discharge pipeline at the top outlet of the liquid-liquid extraction tower 1, and the outlet of the extraction residue cooler 7 is connected to the bottom tray of the extraction residue washing tower 3.

[0055] In this invention, preferably, the bottom of the liquid-liquid extraction tower 1 is provided with an extract discharge pipeline, and the liquid-liquid extraction tower 1 is connected to the top tray of the non-aromatic stripping tower 2 through the extract discharge pipeline.

[0056] In this invention, preferably, the cold-side inlet of the lean solvent / extract heat exchanger 8 is connected to the extract outlet pipeline at the bottom of the liquid-liquid extraction tower 1, and the cold-side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the non-aromatic stripping tower 2.

[0057] In this invention, preferably, the hot-side inlet of the lean solvent / extract heat exchanger 8 is connected to the hot-side outlet of the water stripping column reboiler 16, and the hot-side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the liquid-liquid extraction column 1.

[0058] In this invention, preferably, the device further includes a non-aromatic stripping tower top cooler 9 and a non-aromatic stripping tower top collection tank 10, wherein the inlet of the non-aromatic stripping tower top cooler 9 is connected to the top outlet of the non-aromatic stripping tower 2, and the outlet of the non-aromatic stripping tower top cooler 9 is connected to the inlet of the non-aromatic stripping tower top collection tank 10.

[0059] In this invention, preferably, a stripping non-aromatic hydrocarbon discharge pipeline is provided at the top of the non-aromatic hydrocarbon stripping tower 2.

[0060] In this invention, preferably, the oil phase outlet of the top collection tank 10 of the non-aromatic stripping tower is connected to the backwash liquid inlet at the bottom of the liquid-liquid extraction tower 1.

[0061] In this invention, preferably, the top collection tank 10 of the non-aromatic stripping tower is equipped with a backwash liquid discharge pipeline.

[0062] In this invention, preferably, the aqueous phase outlet of the top collection tank 10 of the non-aromatic stripping tower is connected to the top tray of the water stripping tower 5.

[0063] In this invention, in a preferred embodiment, the non-aromatic stripping tower top collection tank 10 is further provided with a non-aromatic stripping tower top collection tank water-in-water discharge pipeline.

[0064] In this invention, preferably, the bottom of the non-aromatic stripping tower 2 is provided with a rich solvent discharge pipeline, and the non-aromatic stripping tower 2 is connected to the middle inlet of the solvent recovery tower 4 through the rich solvent discharge pipeline.

[0065] In this invention, preferably, the lean solvent outlet at the bottom of the solvent recovery tower 4 is connected to the solvent inlet to be regenerated at the bottom of the solvent regeneration tower 6.

[0066] In this invention, preferably, the apparatus further includes a solvent recovery tower top cooler 11 and a solvent recovery tower reflux tank 12, wherein the inlet of the solvent recovery tower top cooler 11 is connected to the top outlet of the solvent recovery tower 2, and the outlet of the solvent recovery tower top cooler 11 is connected to the inlet of the solvent recovery tower reflux tank 12.

[0067] In this invention, preferably, the aqueous phase outlet of the solvent recovery tower reflux tank 12 is connected to the top tray of the raffinate washing tower 3, and the oil phase outlet of the solvent recovery tower reflux tank 12 is connected to the downstream aromatic product collection tank and the reflux port of the solvent recovery tower 4, respectively.

[0068] In this invention, preferably, the solvent recovery tower 4 is provided with a solvent recovery tower top discharge pipeline.

[0069] In this invention, preferably, the bottom of the extraction residue washing tower 3 is provided with a solvent-containing washing water outlet pipeline, and the extraction residue washing tower 3 is connected to the top tray of the water stripping tower 5 through the solvent-containing washing water outlet pipeline.

[0070] In this invention, preferably, a non-aromatic hydrocarbon discharge pipeline is provided at the top of the extraction residue washing tower 3.

[0071] In this invention, the device further includes a stripping water cooler 17, the inlet of which is connected to the top outlet of the water stripping tower 5, and the outlet of which is connected to the inlet of the top collection tank 10 of the non-aromatic stripping tower.

[0072] In this invention, preferably, the top of the water stripping tower 5 is provided with a stripping water discharge pipeline.

[0073] In this invention, preferably, the bottom solvent recovery outlet of the water stripping tower 5 is connected to the bottom tray of the solvent recovery tower 4.

[0074] In this invention, preferably, the stripping steam outlet of the water stripping tower 5 is connected to the stripping steam inlet at the bottom of the solvent regeneration tower 6.

[0075] In this invention, preferably, the top regenerated solvent outlet of the solvent regeneration tower 6 is connected to the bottom tray of the solvent recovery tower 4.

[0076] In this invention, preferably, the cold side of the heat balancer is connected in series with the cold side of the non-aromatic stripping tower reboiler 13, and more preferably, they are connected in series sequentially.

[0077] In this invention, preferably, the hot-side inlet of the water stripper reboiler 16 is connected to the hot-side outlet of the heat balancer, and the hot-side outlet of the water stripper reboiler 16 is connected to the hot-side inlet of the lean solvent / extract heat exchanger 8.

[0078] In this invention, preferably, the liquid-liquid extraction tower 1 and the residue washing tower 3 are each independently a total liquid phase extraction tower.

[0079] In this invention, preferably, the solvent recovery tower 4 is further provided with a solvent recovery tower reboiler 14.

[0080] In this invention, preferably, the solvent regeneration tower 6 is further provided with a solvent regeneration tower reboiler 15.

[0081] In this invention, preferably, the heat balancer is selected from at least one of a kettle-type heat balancer 18, a thermosiphon-type heat balancer 19, and a shell-and-tube type heat balancer 20.

[0082] According to a preferred embodiment of the present invention, such as Figure 1 As shown, the cold-side inlet of the batch heat balancer 18 is connected to the first outlet of the bottom tray of the non-aromatic stripping tower 2, the cold-side (gas phase) outlet of the batch heat balancer 18 is connected to the first inlet of the bottom of the non-aromatic stripping tower 2, the cold-side (liquid phase) outlet of the batch heat balancer 18 is connected to the cold-side inlet of the bottom reboiler 13 of the non-aromatic stripping tower, and the cold-side outlet of the bottom reboiler 13 of the non-aromatic stripping tower is connected to the second inlet of the bottom of the non-aromatic stripping tower 2.

[0083] In this invention, preferably, the hot-side inlet 42 of the batch heat balancer 18 is connected to the lean solvent outlet at the bottom of the solvent recovery tower 4, the hot-side outlet of the batch heat balancer 18 is connected to the hot-side inlet 39 of the water stripping tower reboiler, the hot-side outlet 40 of the water stripping tower reboiler is connected to the hot-side inlet of the lean solvent / extract heat exchanger 8, and the hot-side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the liquid-liquid extraction tower 1.

[0084] According to another preferred embodiment of the present invention, such as Figure 2 As shown, the cold-side inlet of the thermochromic heat balancer 19 is connected to the first outlet of the bottom tray of the non-aromatic stripping tower 2, the cold-side outlet of the thermochromic heat balancer 19 is connected to the first inlet of the bottom of the non-aromatic stripping tower 2, the first outlet of the bottom of the non-aromatic stripping tower 2 is connected to the cold-side inlet of the bottom reboiler 13 of the non-aromatic stripping tower, and the cold-side outlet of the bottom reboiler 13 of the non-aromatic stripping tower is connected to the second inlet of the bottom of the non-aromatic stripping tower 2.

[0085] In this invention, preferably, the hot-side inlet 42 of the thermoacoustic heat balancer 19 is connected to the lean solvent outlet of the solvent recovery tower 4, the hot-side outlet of the thermoacoustic heat balancer 19 is connected to the hot-side inlet 39 of the water stripping tower reboiler, the hot-side outlet 40 of the water stripping tower reboiler is connected to the hot-side inlet of the lean solvent / extract heat exchanger 8, and the hot-side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the liquid-liquid extraction tower 1.

[0086] According to another preferred embodiment of the present invention, such as Figure 3 As shown, the cold-side inlet of the shell-and-tube heat balancer 20 is connected to the first outlet (after being pressurized by a pump) of the bottom tray of the non-aromatic stripping tower 2, the cold-side outlet of the shell-and-tube heat balancer 20 is connected to the cold-side inlet of the reboiler 13 of the non-aromatic stripping tower, and the cold-side outlet of the reboiler 13 of the non-aromatic stripping tower is connected to the first inlet of the bottom of the non-aromatic stripping tower 2.

[0087] In this invention, preferably, the hot-side inlet 42 of the shell-and-tube heat balancer 20 is connected to the lean solvent outlet at the bottom of the solvent recovery tower 4, the hot-side outlet of the shell-and-tube heat balancer 20 is connected to the hot-side inlet 39 of the reboiler of the water stripping tower, the hot-side outlet 40 of the reboiler of the water stripping tower is connected to the hot-side inlet of the lean solvent / extract heat exchanger 8, and the hot-side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the liquid-liquid extraction tower 1.

[0088] In this invention, there are no particular limitations on the specific types and structures of the liquid-liquid extraction tower 1, the non-aromatic stripping tower 2, the extraction residue washing tower 3, the solvent recovery tower 4, the water stripping tower 5, and the solvent regeneration tower 6. Towers conventionally defined in the art can be applied to this invention.

[0089] A second aspect of the present invention provides a method for separating aromatic hydrocarbons and non-aromatic hydrocarbons by liquid-liquid extraction, wherein the method is carried out in the apparatus described in the first aspect.

[0090] In this invention, preferably, the method is carried out in the presence of an extraction solvent, preferably at least one selected from sulfolane, N,N-dimethylacetamide, N-methylpyrrolidone, and N-formylmorpholine.

[0091] In this invention, preferably, the method is applicable to the separation of hydrocarbon mixtures, wherein the hydrocarbon mixture 21 is preferably a hydrocarbon with 4-20 carbon atoms, and more preferably a hydrocarbon with 5-10 carbon atoms.

[0092] In this invention, the operating conditions of each tower, including liquid-liquid extraction tower 1, non-aromatic stripping tower 2, residue washing tower 3, solvent recovery tower 4, water stripping tower 5, and solvent regeneration tower 6, are not particularly limited, and those skilled in the art can select them according to actual needs.

[0093] The present invention will be described in detail below through embodiments.

[0094] In this invention, it should be noted that the circulating water volume of the water system is based on the water volume of the extraction residue washing tower (water in the reflux tank at the top of the solvent recovery tower).

[0095] Example 1

[0096] Adopting such Figure 1The apparatus shown performs liquid-liquid extraction to separate aromatics and non-aromatics. The apparatus includes a liquid-liquid extraction tower 1, a non-aromatic stripping tower 2, a residue washing tower 3, a solvent recovery tower 4, a water stripping tower 5, a solvent regeneration tower 6, a non-aromatic stripping tower top cooler 9, a non-aromatic stripping tower top collection tank 10, a solvent recovery tower top cooler (not shown), a solvent recovery tower reflux tank 12, a non-aromatic stripping tower reboiler 13, a water stripping tower reboiler 16, a stripping water cooler 17, and a kettle-type heat balancer 18.

[0097] The liquid-liquid extraction tower 1 is provided with a residue discharge pipeline at the top of the tower, and a residue cooler 7 is provided on the residue discharge pipeline. The inlet of the residue cooler 7 is connected to the top outlet of the liquid-liquid extraction tower 1, and the outlet of the residue cooler 7 is connected to the bottom tray of the residue washing tower 3.

[0098] The top of the extraction residue washing tower 3 is equipped with a non-aromatic hydrocarbon discharge pipeline, and the bottom of the extraction residue washing tower 3 is equipped with a solvent-containing washing water discharge pipeline. The extraction residue washing tower 3 is connected to the top tray of the water stripping tower 5 through the solvent-containing washing water discharge pipeline.

[0099] The liquid-liquid extraction tower 1 is equipped with an extract outlet pipeline at the bottom of the tower, and a lean solvent / extractant heat exchanger 8 is installed on the extract outlet pipeline. The cold side inlet of the lean solvent / extractant heat exchanger 8 is connected to the bottom outlet of the liquid-liquid extraction tower 1, and the cold side outlet of the lean solvent / extractant heat exchanger 8 is connected to the top tray of the non-aromatic stripping tower 2.

[0100] The inlet of the non-aromatic stripper top cooler 9 is connected to the top outlet of the non-aromatic stripper 2, and the outlet of the non-aromatic stripper top cooler 9 is connected to the inlet of the non-aromatic stripper top collection tank 10; the oil phase outlet of the non-aromatic stripper top collection tank 10 is connected to the backwash liquid inlet at the bottom of the liquid-liquid extraction tower 1, and the water phase outlet of the non-aromatic stripper top collection tank 10 is connected to the top tray of the water stripper 5.

[0101] The bottom of the non-aromatic stripping tower 2 is equipped with a rich solvent discharge pipeline, and the non-aromatic stripping tower 2 is connected to the middle inlet of the solvent recovery tower 4 through the rich solvent discharge pipeline.

[0102] The inlet of the solvent recovery tower top cooler 11 is connected to the top outlet of the solvent recovery tower 4, and the outlet of the solvent recovery tower top cooler 11 is connected to the inlet of the solvent recovery tower reflux tank 12; the aqueous phase outlet of the solvent recovery tower reflux tank 12 is connected to the top tray of the raffinate washing tower 3, and the oil phase outlet of the solvent recovery tower reflux tank 12 is connected to the downstream aromatic product collection tank and / or the reflux port of the solvent recovery tower 4.

[0103] The bottom outlet of the water stripping tower 5 is connected to the bottom tray of the solvent recovery tower 4; the stripping steam outlet of the water stripping tower 5 is connected to the stripping steam inlet at the bottom of the solvent regeneration tower 6; and the top outlet of the solvent regeneration tower 6 is connected to the bottom tray of the solvent recovery tower 4.

[0104] The inlet of the stripping water cooler 17 is connected to the top outlet of the water stripping tower 5, and the outlet of the stripping water cooler 17 is connected to the inlet of the top collection tank 10 of the non-aromatic stripping tower.

[0105] The cold-side inlet of the batch heat balancer 18 is connected to the first outlet of the bottom tray of the non-aromatic stripping tower 2; the cold-side gas phase outlet of the batch heat balancer 18 is connected to the first inlet of the bottom of the non-aromatic stripping tower 2; the cold-side liquid phase outlet of the batch heat balancer 18 is connected to the cold-side inlet of the reboiler 13 of the non-aromatic stripping tower; and the cold-side outlet of the reboiler 13 of the non-aromatic stripping tower is connected to the second inlet of the bottom of the non-aromatic stripping tower 2. The solvent return... The lean solvent outlet of the collecting tower 4 is connected to the solvent inlet of the solvent regeneration tower 6 and the hot side inlet 42 of the kettle heat balancer 18. The hot side outlet of the kettle heat balancer 18 is connected to the hot side inlet 39 of the water stripping tower reboiler. The hot side outlet 40 of the water stripping tower reboiler is connected to the hot side inlet of the lean solvent / extract heat exchanger 8. The hot side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the liquid-liquid extraction tower 1.

[0106] The specific method is as follows:

[0107] The hydrocarbon mixture 21 is fed to the liquid-liquid extraction tower 1 via the hydrocarbon mixture feed pipeline for liquid-liquid extraction. After extraction with the extraction solvent 41 (the extraction solvent is sulfolane), the raffinate 22 and the extract 23 are obtained.

[0108] After being cooled in the residue cooler 7 via the residue discharge pipeline, the residue 22 enters the residue washing tower 3 from the bottom tray of the tower for washing, yielding non-aromatic hydrocarbons 34 and solvent-containing wash water 35. The non-aromatic hydrocarbons 34 are transported to the outside as a product via the non-aromatic hydrocarbon discharge pipeline, while the solvent-containing wash water 35 is transported to the top tray of the water stripping tower 5 for further processing via the solvent-containing wash water discharge pipeline.

[0109] Extract 23 is sent to lean solvent / extract heat exchanger 8 via extract outlet pipeline for heat exchange, and then sent to non-aromatic stripping tower 2 for non-aromatic removal to obtain stripped non-aromatic hydrocarbon 24 and rich solvent 27.

[0110] The stripped non-aromatic hydrocarbons 24 are fed into the non-aromatic hydrocarbon stripping cooler 9 via the stripped non-aromatic hydrocarbon discharge pipeline at the top outlet of the non-aromatic hydrocarbon stripping tower 2 for cooling, and then sent to the non-aromatic hydrocarbon stripping tower collection tank 10 for oil-water separation, yielding wash liquid 25 and water-in-water 26 in the non-aromatic hydrocarbon stripping tower top collection tank. The wash liquid 25 is returned to the wash liquid inlet at the bottom of the liquid-liquid extraction tower 1 via the oil phase outlet of the non-aromatic hydrocarbon stripping tower top collection tank 10; the water-in-water 26 in the non-aromatic hydrocarbon stripping tower top collection tank is then separated into oil and water. The aqueous phase outlet of the aromatic stripping tower top collection tank 10 is mixed with solvent-containing wash water 35 through the water-in-water discharge pipeline of the non-aromatic stripping tower top collection tank and then transported to the top tray of the water stripping tower 5 for processing to obtain stripping water 36, stripping steam 37 and recovered solvent 38. The stripping water 36 is cooled by the stripping water cooler 17 and then sent to the non-aromatic stripping tower collection tank 10. The stripping steam 37 is sent to the solvent regeneration tower 6 and the recovered solvent 38 is sent to the bottom tray of the solvent recovery tower 4.

[0111] The rich solvent 27 is fed into the solvent recovery tower 4 through the middle inlet of the rich solvent discharge pipeline for solvent recovery, resulting in lean solvent 30 and top material. The top material is cooled by the solvent recovery tower top cooler 11 and then enters the solvent recovery tower reflux tank 12 for oil-water separation. The water-in-water 29 of the solvent recovery tower top reflux tank is sent to the top tray of the raffinate washing tower as washing water through the water phase outlet of the solvent recovery tower top reflux tank 12. Part of the aromatics are transported to the downstream aromatics collection tank as aromatics product 28, and the remaining aromatics are returned to the solvent recovery tower 4 as reflux.

[0112] Most of the lean solvent 30 is fed into the heat balancer 18 via the hot-side inlet 42 of the lean solvent discharge pipeline. Then, it is fed into the water stripper reboiler 16 via the hot-side outlet of the heat balancer 18 and the hot-side inlet 39 of the water stripper reboiler. After that, it is fed into the lean solvent / extractant heat exchanger 8 via the hot-side outlet 40 of the water stripper reboiler and the hot-side inlet of the lean solvent / extractant heat exchanger 8. As the extraction solvent, it is returned to the top tray of the liquid-liquid extraction tower 1 via the hot-side outlet of the lean solvent / extractant heat exchanger 8. A small portion of the lean solvent 30 is fed into the solvent regeneration tower 6 via the lean solvent discharge pipeline as the solvent to be regenerated 31 (the proportion of solvent to be regenerated 31 to lean solvent 30 is 1% wt) to obtain regenerated solvent 32 and waste solvent 33.

[0113] The regenerated solvent 32 is sent to the bottom tray of the solvent recovery tower 4 through the top outlet of the solvent regeneration tower 6.

[0114] The theoretical number of plates in liquid-liquid extraction column 1 is 15, and the operating pressure at the top of the column is 0.6 MPaG; the theoretical number of plates in non-aromatic stripping column 2 is 25, and the operating pressure at the top of the column is 0.13 MPaG; the theoretical number of plates in raffinate washing column 3 is 3, and the operating pressure at the top of the column is 0.3 MPaG; the theoretical number of plates in solvent recovery column 4 is 25, and the operating pressure at the top of the column is -0.05 MPaG; the theoretical number of plates in water stripping column 5 is 4, and the operating pressure at the top of the column is 0.07 MPaG; and the theoretical number of plates in solvent regeneration column 6 is 1, and the operating pressure at the top of the column is -0.01 MPaG.

[0115] Example 2

[0116] Adopting such Figure 2 The apparatus shown performs liquid-liquid extraction to separate aromatics and non-aromatics. Unlike Example 1, it includes a thermoacoustic heat balancer 19. The cold-side inlet of the thermoacoustic heat balancer 19 is connected to the first outlet of the bottom tray of the non-aromatic stripping column 2. The cold-side outlet of the thermoacoustic heat balancer 19 is connected to the first inlet of the bottom tray of the non-aromatic stripping column 2. The first outlet of the bottom tray of the non-aromatic stripping column 2 is connected to the cold-side inlet of the reboiler 13 of the non-aromatic stripping column. The outlet is connected to the second inlet of the bottom of the non-aromatic stripping tower 2; the hot side inlet 42 of the thermo-sink heat balancer 19 is connected to the lean solvent outlet of the solvent recovery tower 4; the hot side outlet of the thermo-sink heat balancer 19 is connected to the hot side inlet 39 of the reboiler 16 of the water stripping tower; the hot side outlet of the reboiler 16 of the water stripping tower is connected to the hot side inlet of the lean solvent / extract heat exchanger 8; and the hot side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the liquid-liquid extraction tower 1.

[0117] Example 3

[0118] Adopting such Figure 3 The apparatus shown performs liquid-liquid extraction to separate aromatics and non-aromatics. Unlike Example 1, it is equipped with a shell-and-tube heat balancer 20. The first outlet of the bottom tray of the non-aromatic stripping tower 2 is pressurized by a pump and connected to the cold-side inlet of the shell-and-tube heat balancer 20. The cold-side outlet of the shell-and-tube heat balancer 20 is connected to the cold-side inlet of the reboiler 13 of the non-aromatic stripping tower. The cold-side outlet of the reboiler 13 of the non-aromatic stripping tower is connected to the first inlet of the bottom of the non-aromatic stripping tower 2. The hot-side inlet 42 of the shell-and-tube heat balancer 20 is connected to the lean solvent outlet of the solvent recovery tower 4. The hot-side outlet of the shell-and-tube heat balancer 20 is connected to the hot-side inlet 39 of the reboiler of the water stripping tower. The hot-side outlet 40 of the reboiler of the water stripping tower is connected to the hot-side inlet of the lean solvent / extract heat exchanger 8. The hot-side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the liquid-liquid extraction tower 1.

[0119] Comparative Examples 1-3

[0120] Comparative Examples 1-3 all adopted the following method: Figure 4 The apparatus shown performs liquid-liquid extraction to separate aromatics and non-aromatics. Comparative Examples 1-3 differ from Examples 1, 2, and 3 in that they do not include a kettle-type heat balancer 18, a thermopillar-type heat balancer 19, or a shell-and-tube heat balancer 20. The cold-side inlet of the non-aromatic stripper reboiler 13 is connected to the first outlet of the bottom tray of the non-aromatic stripper 2, and the cold-side outlet of the non-aromatic stripper reboiler 13 is connected to the first inlet of the bottom tray of the non-aromatic stripper 2. The hot-side inlet 39 of the water stripper reboiler is connected to the lean solvent outlet of the solvent recovery tower 4, and the hot-side outlet 40 of the water stripper reboiler is connected to the hot-side inlet of the lean solvent / extract heat exchanger 8. The hot-side outlet of the lean solvent / extract heat exchanger 8 is connected to the top tray of the liquid-liquid extraction tower 1.

[0121] The composition of the hydrocarbon mixtures in the above embodiments and comparative examples is shown in Table 1, and the extraction and separation results are shown in Table 2.

[0122] Table 1

[0123]

[0124]

[0125] Table 2

[0126]

[0127]

[0128] As can be seen from the comparison results in Table 2, under the premise of the same raw material and solvent ratio, by using the device and method of the present invention and setting up a heat balancer, under the condition that the quality of non-aromatic and aromatic products is similar, it is possible to achieve precise matching between the waste heat of lean solvent and the water volume of the water circulation system, realize the efficient utilization of waste heat of lean solvent, and ultimately achieve efficient heat balance of the entire device, and reduce the total heat load of system steam consumption by 11%.

[0129] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An apparatus for liquid-liquid extraction to separate aromatic hydrocarbons from non-aromatic hydrocarbons, wherein, The apparatus includes interconnected liquid-liquid extraction tower (1), non-aromatic stripping tower (2), raffinate washing tower (3), solvent recovery tower (4), water stripping tower (5), solvent regeneration tower (6), non-aromatic stripping tower reboiler (13), lean solvent / extractant heat exchanger (8), water stripping tower reboiler (16), and heat balancer. The cold side inlet of the heat balancer is connected to the first outlet of the bottom tray of the non-aromatic stripping tower (2), and the cold side outlet of the heat balancer is connected to the first inlet of the bottom of the non-aromatic stripping tower (2) and / or the cold side inlet of the reboiler (13) of the non-aromatic stripping tower. The hot side inlet (42) of the heat balancer is connected to the lean solvent outlet at the bottom of the solvent recovery tower (4), and the hot side outlet of the heat balancer is connected in sequence to the hot side of the water stripping tower reboiler (16), the hot side of the lean solvent / extractant heat exchanger (8), and the top tray of the liquid-liquid extraction tower (1).

2. The apparatus according to claim 1, wherein, The liquid-liquid extraction tower (1) is provided with a residue discharge pipeline at the top of the tower, and the liquid-liquid extraction tower (1) is connected to the bottom tray of the residue washing tower (3) through the residue discharge pipeline. Preferably, an extractant cooler (7) is provided on the extractant discharge pipeline, the inlet of the extractant cooler (7) is connected to the extractant discharge pipeline at the top of the liquid-liquid extraction tower (1), and the outlet of the extractant cooler (7) is connected to the bottom tray of the extractant washing tower (3).

3. The apparatus according to claim 1 or 2, wherein, The liquid-liquid extraction tower (1) is provided with an extract discharge pipeline at the bottom of the tower, and the liquid-liquid extraction tower (1) is connected to the top tray of the non-aromatic stripping tower (2) through the extract discharge pipeline; Preferably, the cold side inlet of the lean solvent / extract heat exchanger (8) is connected to the extract outlet pipeline at the bottom of the liquid-liquid extraction tower (1), and the cold side outlet of the lean solvent / extract heat exchanger (8) is connected to the top tray of the non-aromatic stripping tower (2). Preferably, the hot-side inlet of the lean solvent / extract heat exchanger (8) is connected to the hot-side outlet of the water stripping column reboiler (16), and the hot-side outlet of the lean solvent / extract heat exchanger (8) is connected to the top tray of the liquid-liquid extraction column (1).

4. The apparatus according to claim 1 or 2, wherein, The apparatus also includes a non-aromatic stripper top cooler (9) and a non-aromatic stripper top collection tank (10). The inlet of the non-aromatic stripper top cooler (9) is connected to the top outlet of the non-aromatic stripper (2), and the outlet of the non-aromatic stripper top cooler (9) is connected to the inlet of the non-aromatic stripper top collection tank (10). Preferably, the oil phase outlet of the top collection tank (10) of the non-aromatic stripping tower is connected to the backwash liquid inlet at the bottom of the liquid-liquid extraction tower (1); Preferably, the aqueous phase outlet of the top collection tank (10) of the non-aromatic stripper is connected to the top tray of the water stripper (5).

5. The apparatus according to claim 1 or 2, wherein, The bottom of the non-aromatic stripping tower (2) is provided with a rich solvent discharge pipeline, and the non-aromatic stripping tower (2) is connected to the middle inlet of the solvent recovery tower (4) through the rich solvent discharge pipeline.

6. The apparatus according to claim 1 or 2, wherein, The lean solvent outlet at the bottom of the solvent recovery tower (4) is connected to the solvent inlet to be regenerated at the bottom of the solvent regeneration tower (6); Preferably, the apparatus further includes a solvent recovery tower top cooler (11) and a solvent recovery tower reflux tank (12), wherein the inlet of the solvent recovery tower top cooler (11) is connected to the top outlet of the solvent recovery tower (4), and the outlet of the solvent recovery tower top cooler (11) is connected to the inlet of the solvent recovery tower reflux tank (12); Preferably, the aqueous phase outlet of the solvent recovery tower reflux tank (12) is connected to the top tray of the raffinate washing tower (3), and the oil phase outlet of the solvent recovery tower reflux tank (12) is connected to the downstream aromatic product collection tank and the reflux port of the solvent recovery tower (4), respectively.

7. The apparatus according to claim 1 or 2, wherein, The bottom of the extraction residue washing tower (3) is provided with a solvent-containing washing water outlet pipeline, and the extraction residue washing tower (3) is connected to the top tray of the water stripping tower (5) through the solvent-containing washing water outlet pipeline.

8. The apparatus according to claim 1 or 2, wherein, The apparatus also includes a stripping water cooler (17), the inlet of which is connected to the top outlet of the water stripping tower (5), and the outlet of which is connected to the inlet of the top collection tank (10) of the non-aromatic stripping tower. Preferably, the bottom solvent recovery outlet of the water stripping tower (5) is connected to the bottom tray of the solvent recovery tower (4); Preferably, the stripping steam outlet of the water stripping tower (5) is connected to the stripping steam inlet at the bottom of the solvent regeneration tower (6); Preferably, the top regenerated solvent outlet of the solvent regeneration tower (6) is connected to the bottom tray of the solvent recovery tower (4).

9. The apparatus according to claim 1 or 2, wherein, The cold side of the heat balancer is connected in series with the cold side of the non-aromatic stripper reboiler (13), preferably in series sequentially; Preferably, the hot-side inlet of the water stripper reboiler (16) is connected to the hot-side outlet of the heat balancer, and the hot-side outlet of the water stripper reboiler (16) is connected to the hot-side inlet of the lean solvent / extract heat exchanger (8). Preferably, the liquid-liquid extraction tower (1) and the residue washing tower (3) are each independently a total liquid phase extraction tower; Preferably, the heat balancer is selected from at least one of a kettle heat balancer (18), a thermoacoustic heat balancer (19), and a shell-and-tube heat balancer (20).

10. A method for separating aromatic hydrocarbons and non-aromatic hydrocarbons by liquid-liquid extraction, wherein, The method is performed in the apparatus described in any one of claims 1-9.

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