Hexane refined gas recovery system

Abstract

The utility model belongs to the field of chemical gas recovery, and particularly relates to a hexane refined gas recovery system which comprises a hexane rectifying tower, a tower top condenser, a drying adsorption tower, a gas phase recovery conveying pipeline and a hexane recovery three-phase separator, the top of the hexane rectifying tower is connected to the tower top condenser through a tower top gas phase outlet pipeline, a gas phase outlet of the tower top condenser is connected to the drying adsorption tower through a pipeline, one end of the gas phase recovery conveying pipeline is communicated with a tower bottom outlet of the drying adsorption tower, and the other end of the gas phase recovery conveying pipeline is connected to the flash evaporation system; a return elbow is arranged on the gas-phase recovery conveying pipeline, the conveying direction of the gas-phase recovery conveying pipeline is turned at the position of the return elbow, the lowest point of the return elbow is the lowest point of the gas-phase recovery conveying pipeline, a drain valve is arranged at the lowest point of the return elbow, and an outlet of the drain valve is connected to a hexane recovery three-phase separator through a liquid hexane conveying pipeline. According to the system, hexane is recycled, the stability of the system is ensured, and the operation of a polymerization unit is prevented from being influenced.

Description

Technical Field

[0001] The utility model belongs to the field of chemical gas recovery, and in particular relates to a hexane refined gas recovery system. Background Art

[0002] Polyethylene (PE), one of the five major synthetic resins, is the synthetic resin with the largest production capacity and the largest import volume in my country. Currently, my country is the world's largest importer and second-largest consumer of PE. Polyethylene is primarily classified into three categories: linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and high-density polyethylene (HDPE). PE is the most widely used general-purpose synthetic resin, with film being its primary processed product, followed by sheet and coatings; hollow containers such as bottles, cans, and barrels; various other injection-molded and blow-molded products; pipes; and insulation and sheathing for wire and cable. PE is primarily used in packaging, agriculture, and transportation. With the development of the petrochemical industry, my country's polyethylene production has grown rapidly, now accounting for approximately a quarter of all plastics production.

[0003] Hexane, a key raw material for polyethylene production, requires refined hexane for catalyst dilution during catalyst processing. During the refined hexane processing and production process, a gas phase is generated at the top of the hexane distillation tower. This gas phase primarily consists of recyclable gases such as hexane, ethylene, and butene. During this recovery process, the hexane gas loses temperature, condenses into a liquid, and forms a liquid seal, hindering the normal transport of the gas phase. In severe cases, the pressure at the top of the hexane distillation tower rises, causing production abnormalities. Summary of the Invention

[0004] In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a hexane refined gas recovery system to recover hexane and ensure the stable operation of the hexane refining system.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a hexane refined gas recovery system, comprising a hexane distillation tower, a top condenser, a drying adsorption tower, a gas recovery and delivery pipeline, and a hexane recovery three-phase separator; the top of the hexane distillation tower is connected to the top condenser through a top gas phase outlet pipeline, and the gas phase outlet of the top condenser is connected to the drying adsorption tower through a pipeline, one end of the gas phase recovery and delivery pipeline is connected to the bottom outlet of the drying adsorption tower, and the other end of the gas phase recovery and delivery pipeline is connected to a flash evaporation system; a return bend pipe is provided on the gas phase recovery and delivery pipeline, and the delivery direction of the gas phase recovery and delivery pipeline turns at the return bend pipe position, and the lowest point of the return bend pipe is the lowest point of the gas phase recovery and delivery pipeline. A shower valve is provided at the lowest point of the return bend pipe, and the outlet of the shower valve is connected to the hexane recovery three-phase separator through a liquid hexane delivery pipeline.

[0006] Furthermore, the return bend pipe is a U-shaped return bend pipe, and both ends of the return bend pipe are connected to the gas phase recovery and transportation pipeline.

[0007] Based on the above technical solution, the gas phase recovery and transportation pipeline is connected to the bottom of the drying adsorption tower at one end and to the flash evaporation system at the other end. The gas phase dehydrated by the drying adsorption tower is transported to the flash evaporation system via the gas phase recovery and transportation pipeline. The gas phase recovery and transportation pipeline is provided with a return bend pipe. The transportation direction of the gas phase recovery and transportation pipeline changes at the return bend pipe position. The lowest point of the return bend pipe is the lowest end of the gas phase recovery and transportation pipeline. When the gas phase dehydrated by the drying adsorption tower is transported on the gas phase recovery and transportation pipeline, it is first transported downward to the return bend pipe position, and then turned to be transported upward through the bottom end of the U-shaped return bend pipe. As a preferred technical solution, the return bend pipe has a U-shaped structure.

[0008] A drip valve is installed at the bottom of the return bend on the gas phase recovery and transportation pipeline. Since the temperature of the drying adsorption tower is approximately 43°C, the dehydrated gas phase will lose some temperature during transportation in the gas phase recovery pipeline, causing the hexane in the gas phase to liquefy and condense at the return bend. The drip valve filters and recovers the liquefied hexane, and the remaining gas phase is transported to the flash evaporation system through the gas phase recovery and transportation pipeline. The function and role of the drip valve is to achieve the "gas-not-liquid" function. That is, at the drip valve position, the gas phase and liquid phase pass through the drip valve together. The gas phase can pass through the drip valve and be transported downstream, while the liquid phase is discharged through the drip valve. That is, the liquid hexane can be recovered at the drip valve position.

[0009] Furthermore, the hexane recovery three-phase separator is connected to a separator inlet pipeline, the liquid hexane delivery pipeline is connected to the separator inlet pipeline, and nitrogen enters the hexane recovery three-phase separator through the separator inlet pipeline to maintain pressure.

[0010] Furthermore, a front gate valve, a regulating valve and a rear gate valve are sequentially arranged on the separator inlet pipeline, and the outlet of the liquid hexane delivery pipeline is connected between the front gate valve and the regulating valve.

[0011] Furthermore, a liquid hexane outlet valve is provided at the outlet of the liquid hexane delivery pipeline.

[0012] Furthermore, the liquid hexane delivery pipeline is an inclined pipeline, and the liquid hexane is inclined downward from the shower valve to the hexane recovery three-stage separator.

[0013] Furthermore, the hexane liquid separated in the hexane recovery three-stage separator is sent to a hexane tank through a pipeline.

[0014] Furthermore, the hexane refined gas recovery system also includes a top reflux tank, a top reflux pump and a reflux pipeline. The liquid phase outlet of the top condenser is connected to the top reflux tank through a pipeline, the outlet of the top reflux tank is connected to the top gas phase outlet pipeline through a reflux pipeline and a top reflux pump, and the reflux pipeline downstream of the top reflux pump is connected to the inlet of the top reflux tank through a reflux branch pipe.

[0015] Furthermore, the bottom outlet of the hexane distillation tower is sequentially connected to a distillation tower bottom discharge pump, a bottom hexane cooler and a refined hexane adsorption purification tower through a bottom outlet pipeline.

[0016] Furthermore, a hexane refining reboiler is provided at the bottom of the hexane distillation tower.

[0017] The beneficial effects of the utility model are as follows: the hexane refining gas recovery system recycles hexane, ensuring the stable operation of the hexane refining system; when the drying adsorption tower does not absorb enough water, the water can be recovered to the three-phase separator for separation, so as not to affect the stable operation of the polymerization unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a process flow chart of the hexane refined gas recovery system of the present utility model;

[0019] Figure 1: Hexane distillation tower, 2: Top gas phase outlet pipeline, 3: Top condenser, 4: Drying adsorption tower, 5: Gas phase recovery pipeline, 6: Return bend, 7: Drain valve, 8: Liquid hexane pipeline, 9: Hexane recovery three-phase separator, 10: Separator inlet pipeline, 11: Front gate valve, 12: Control valve, 13: Rear gate valve, 14: Liquid hexane outlet valve, 15: Top reflux tank, 16: Top reflux pump, 17: Reflux pipeline, 18: Reflux branch pipe, 19: Bottom outlet pipeline, 20: Distillation tower bottom discharge pump, 21: Bottom hexane cooler, 22: Hexane refining reboiler.

[0020] A. Flash evaporation system, B. Refined hexane adsorption purification tower. DETAILED DESCRIPTION

[0021] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] See attached Figure 1A hexane refined gas recovery system is used for hexane refining and gas phase resource recovery, comprising a hexane distillation tower 1, a tower top condenser 3, a drying adsorption tower 4, a gas phase recovery and delivery pipeline, and a hexane recovery three-stage separator; the top of the hexane distillation tower 1 is connected to the tower top condenser 3 through a tower top gas phase outlet pipeline 2, the gas phase outlet of the tower top condenser 3 is connected to the drying adsorption tower 4 through a pipeline, one end of the gas phase recovery and delivery pipeline 5 is connected to the tower bottom outlet of the drying adsorption tower 4, and the gas phase recovery and delivery pipeline 5 is connected to the tower bottom outlet of the drying adsorption tower 4. The other end of the pipeline 5 is connected to the flash evaporation system A; the gas phase recovery and conveying pipeline 5 is provided with a U-shaped bend pipe 6, both ends of the bend pipe 6 are connected to the gas phase recovery and conveying pipeline 5, and the conveying direction of the gas phase recovery and conveying pipeline 5 turns at the bend pipe 6. The lowest point of the bend pipe 6 is the lowest point of the gas phase recovery and conveying pipeline 5. A drain valve 7 is provided at the lowest point of the bend pipe 6, and the outlet of the drain valve 7 is connected to the hexane recovery three-phase separator 9 through the liquid hexane conveying pipeline 8.

[0023] Furthermore, the inlet of the hexane recovery three-phase separator 9 is connected to a separator inlet pipeline 10, the liquid hexane delivery pipeline 8 is connected to the separator inlet pipeline 10, and nitrogen enters the hexane recovery three-phase separator 9 through the separator inlet pipeline 10 to maintain pressure.

[0024] Furthermore, a front gate valve 11 , a regulating valve 12 and a rear gate valve 13 are sequentially provided on the separator inlet pipeline 10 , and the outlet of the liquid hexane delivery pipeline 8 is connected between the front gate valve 11 and the regulating valve 12 .

[0025] Furthermore, a liquid hexane outlet valve 14 is provided at the outlet of the liquid hexane delivery pipeline 8 .

[0026] Furthermore, the liquid hexane delivery pipeline 8 is an inclined pipeline, and the liquid hexane is inclined downward from the shower valve 7 to the hexane recovery three-stage separator 9.

[0027] Furthermore, the hexane liquid separated in the hexane recovery three-stage separator 9 is sent to a hexane tank through a pipeline.

[0028] Furthermore, the hexane refined gas recovery system also includes a top reflux tank 15, a top reflux pump 16 and a reflux pipeline 17. The liquid phase outlet of the top condenser 3 is connected to the top reflux tank 15 through a pipeline, and the outlet of the top reflux tank 15 is connected to the top gas phase outlet pipeline 2 through the reflux pipeline 17 and the top reflux pump 16. The reflux pipeline downstream of the top reflux pump 16 is connected to the inlet of the top reflux tank 15 through a reflux branch pipe 18.

[0029] Furthermore, the bottom outlet of the hexane distillation tower 1 is sequentially connected to a distillation tower bottom discharge pump 20, a bottom hexane cooler 21 and a refined hexane adsorption purification tower through a bottom outlet pipeline 19.

[0030] Furthermore, a hexane refining reboiler 22 is provided at the bottom of the hexane distillation tower 1 .

[0031] The hexane distillation tower is used to distill hexane. The hexane is transported to the hexane distillation tower through a pipeline for distillation. The hexane after distillation is recycled. The operating temperature of the hexane distillation tower is about 80°C. The hexane distillation tower will produce hexane vapor and water vapor during operation. The above gases will rise to the top of the hexane distillation tower. As time goes by, the amount of gas accumulated at the top of the hexane distillation tower continues to increase.

[0032] The bottom hexane cooler is connected to the bottom of the hexane distillation tower through the bottom outlet pipeline. It is used to cool the hexane transported from the hexane distillation tower and reduce the hexane temperature from 85°C to 43°C. The purpose is to condense the hexane gas into liquid for recycling.

[0033] The distillation tower bottom discharge pump is arranged on a pipeline connected to the hexane distillation tower and the tower bottom hexane cooler. The distillation tower discharge pump provides a power source for transporting the liquid hexane in the hexane distillation tower to the tower bottom hexane cooler.

[0034] The refined hexane adsorption purification tower is connected to the hexane cooler at the bottom of the tower and performs adsorption purification treatment on the hexane delivered from the hexane distillation tower.

[0035] The hexane tank is connected to the refined hexane adsorption purification tower through a pipeline. After the refined hexane adsorption purification tower adsorbs and purifies the hexane, the hexane is passed into the hexane tank through a transmission pipeline for storage.

[0036] The drying adsorption tower is connected to the top condenser through a pipeline. The gas outlet of the hexane distillation tower is located at the upper top of the hexane distillation tower, and the gas inlet of the hexane drying adsorption tower is located at the upper top of the drying adsorption tower, that is, the upper top of the drying adsorption tower is connected to the top condenser, and the top condenser is connected to the upper top of the hexane distillation tower through a pipeline. The gas phase at the upper top of the hexane distillation tower is transported to the top condenser through the pipeline, and the uncondensed part of the gas phase at the top of the top condenser is sent to the drying adsorption tower. The drying adsorption tower dehydrates the gas phase transported by the top condenser.

[0037] The gas phase recovery and conveying pipeline has one end connected to the bottom of the drying adsorption tower and the other end connected to the flash evaporation system. The gas phase dehydrated in the drying adsorption tower is transported to the flash evaporation system via the gas phase recovery and conveying pipeline. The gas phase recovery and conveying pipeline is equipped with a return bend pipe. The gas phase recovery and conveying pipeline has its conveying direction turned at the return bend pipe position. The lowest point of the return bend pipe is the lowest end of the gas phase recovery and conveying pipeline. When the gas phase dehydrated in the drying adsorption tower is transported on the gas phase recovery and conveying pipeline, it is first transported downward to the return bend pipe position, and then transferred upward through the bottom end of the U-shaped return bend pipe. As a preferred technical solution, the return bend pipe has a U-shaped structure.

[0038] Trickle valve: Installed at the bottom of the return bend on the gas phase recovery pipeline, due to the temperature of the drying adsorption tower being approximately 43°C, the dehydrated gas will experience some temperature loss during transportation in the gas phase recovery pipeline, causing the hexane in the gas phase to liquefy and condense at the return bend. The trickle valve filters and recovers the liquefied hexane, while the remaining gas phase is transported to the flash evaporation system via the gas phase recovery pipeline. The trickle valve's function is to achieve "gas-only but not liquid-only" functionality. That is, at the trickle valve location, the gas and liquid phases pass through the trickle valve together, with the gas phase passing through the trickle valve and being transported downstream, while the liquid phase is discharged through the trickle valve, meaning that the liquid hexane can be recovered at the trickle valve location.

[0039] The top of the hexane distillation tower is equipped with an overhead condenser, an overhead reflux tank, and an overhead reflux pump. These condensers, reflux tanks, and pumps liquefy the hexane vapor phase at the top of the hexane distillation tower, reducing the hexane content in the vapor phase at the top of the tower.

[0040] The overhead condenser is installed on the pipeline connecting the hexane distillation tower and the drying adsorption tower. The hexane, water vapor, ethylene, butene, and other vapors at the top of the hexane distillation tower are transported to the overhead condenser through the pipeline. The overhead condenser is used to cool the vapors at the top of the hexane distillation tower.

[0041] The top reflux tank is arranged downstream of the top condenser. The hexane liquid and other gas phases condensed in the top condenser enter the reflux tank together. After cooling treatment in the top condenser, part of the gas phase hexane and gaseous water are liquefied and mixed, and settle to the bottom of the top reflux tank. The top reflux tank collects the mixed liquid hexane of the condensed liquid phase and liquid phase water.

[0042] The tower top reflux pump is arranged downstream of the reflux tank.

[0043] In this embodiment, the hexane is recovered by connecting the liquid hexane delivery pipeline 8 to the hexane recovery three-stage separator 9 .

[0044] One end of the liquid hexane delivery pipeline is connected to the shower valve, and the other end of the liquid hexane delivery pipeline is connected to the hexane recovery three-phase separator. The hexane recovery three-phase separator purifies and separates the liquid hexane, and the liquid hexane is recovered and processed at the position of the hexane recovery three-phase separator.

[0045] In one embodiment of the present invention, the liquid hexane delivery pipeline is an inclined pipeline, and the liquid hexane is inclined downward from the shower valve to the hexane recovery three-stage separator. The inclined installed liquid hexane delivery pipeline is conducive to the flow of liquid hexane relying on its own gravity.

[0046] In one embodiment of the present invention, the pressure at the location of the drain valve is greater than the pressure of the hexane recovery three-phase separator, so that the liquid hexane at the location of the drain valve is transported to the hexane recovery three-phase separator through a positive pressure environment. In conjunction with the tilted installation of the liquid hexane delivery pipeline, the liquid hexane can be stably transported to the hexane recovery three-phase separator for purification. The hexane recovery three-phase separator is a reflux tank with a built-in baffle, which plays a separation role. A storage tank is set at the bottom of the hexane recovery three-phase separator, and water is drained through the storage tank. The hexane liquid recovered in the hexane recovery three-phase separator is transported to the hexane tank through a pipeline, and the gas phase in the hexane recovery three-phase separator is heat exchanged or burned and discharged through the exhaust system.

[0047] Working principle: First, the hexane after the polymerization reaction is passed into the hexane distillation tower for distillation treatment. The temperature of the hexane distillation tower is about 80°C. During the distillation process, some hexane vapor, water vapor, ethylene gas, and butene gas will be generated and rise to the top of the hexane distillation tower. The liquid hexane in the hexane distillation tower is transported to the hexane cooler through a pipeline in conjunction with the distillation tower discharge pump installed on the pipeline. The liquid hexane transported from the hexane distillation tower is cooled to reduce its temperature from 85°C to 43°C. After the hexane is cooled, the hexane in the hexane cooler is transported to the adsorption purification tower through a pipeline for adsorption purification treatment. The hexane after adsorption purification is transported to the hexane tank through a pipeline for storage.

[0048] The gas phase in the hexane distillation tower floats on the top of the tower. This part of the gas phase is transported to the top condenser through a pipeline for cooling, and then transported to the top reflux tank through a pipeline. The gas phase hexane and water vapor in the top reflux tank are pre-cooled and liquefied due to the lowering of temperature and settle at the bottom of the reflux tank. The liquid phase water and liquid phase hexane are separated by the baffle in the top reflux tank. The uncondensed part at the top of the top condenser is transported through a pipeline to the drying adsorption tower, which dehydrates the gas phase. The dehydrated gas phase passes through the gas phase recovery pipeline for gas phase separation and recovery process. At this time, the main components of the gas phase are hexane, ethylene and butene. The gas phase in the gas phase recovery and transmission pipeline will produce temperature loss phenomenon, and the hexane will be liquefied after cooling. The liquid hexane is recovered at the bend position of the gas phase recovery and transmission pipeline, and the liquid hexane is transported to the three-phase separator through the liquid hexane transmission pipeline through the guide valve. The ethylene and butene gas phases are transported to the flash evaporation system through the gas phase recovery and transmission pipeline, and then the butene is recovered and processed through the butene recovery system.

[0049] Butene Recovery System: The butene recovery system recovers butene gas. The system primarily consists of a compressor, pipelines, and a recovery tower. After being compressed by the compressor, the recovered gas is piped to the recovery tower. The butene is cooled with hexane liquid and then returned to the reaction liquid phase pipeline along with the hexane. Uncondensed gas, including ethylene, is returned to the reaction gas phase pipeline via the top of the tower.

[0050] It should be noted that the parts not described in detail in the present invention are prior art.

[0051] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0053] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0054] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0055] In the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship. "At least one" means one or more; "at least one of A and B" is similar to "A and / or B", describing the association relationship of associated objects, indicating that three relationships may exist. For example, at least one of A and B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0056] The above examples are merely preferred embodiments of the present invention. Obviously, the present invention is not limited to the above examples and is subject to numerous variations. Any variations that can be directly derived or conceived by a person skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A hexane refined gas recovery system, characterized by: It includes a hexane distillation tower, a top condenser, a drying adsorption tower, a gas phase recovery and delivery pipeline, and a hexane recovery three-phase separator; the top of the hexane distillation tower is connected to the top condenser through a top gas phase outlet pipeline, the gas phase outlet of the top condenser is connected to the drying adsorption tower through a pipeline, one end of the gas phase recovery and delivery pipeline is connected to the bottom outlet of the drying adsorption tower, and the other end of the gas phase recovery and delivery pipeline is connected to a flash evaporation system; a return bend pipe is provided on the gas phase recovery and delivery pipeline, and the delivery direction of the gas phase recovery and delivery pipeline turns at the return bend pipe position, the lowest point of the return bend pipe is the lowest point of the gas phase recovery and delivery pipeline, a shower valve is provided at the lowest point of the return bend pipe, and the outlet of the shower valve is connected to the hexane recovery three-phase separator through a liquid hexane delivery pipeline.

2. A hexane refined gas recovery system according to claim 1, characterized in that: The return bend pipe is a U-shaped return bend pipe, and both ends of the return bend pipe are connected to the gas phase recovery and transportation pipeline.

3. A hexane refined gas recovery system according to claim 1, characterized in that: The hexane recovery three-phase separator is connected to a separator inlet pipeline, the liquid hexane delivery pipeline is connected to the separator inlet pipeline, and nitrogen enters the hexane recovery three-phase separator through the separator inlet pipeline to maintain pressure.

4. A hexane refined gas recovery system according to claim 3, characterized in that: The separator inlet pipeline is sequentially provided with a front gate valve, a regulating valve and a rear gate valve, and the outlet of the liquid hexane delivery pipeline is connected between the front gate valve and the regulating valve.

5. A hexane refined gas recovery system according to claim 3, characterized in that: The liquid hexane delivery pipeline is provided with a liquid hexane outlet valve at the outlet.

6. A hexane purified gas recovery system according to claim 1, characterized in that: The liquid hexane delivery pipeline is an inclined pipeline, and the liquid hexane is inclined downward from the shower valve to the hexane recovery three-stage separator.

7. A hexane purified gas recovery system according to claim 1, characterized in that: The hexane liquid separated in the hexane recovery three-stage separator is sent to the hexane tank through a pipeline.

8. A hexane purified gas recovery system according to any one of claims 1 to 7, characterized in that: It also includes a top reflux tank, a top reflux pump and a reflux pipeline. The liquid phase outlet of the top condenser is connected to the top reflux tank through a pipeline, the outlet of the top reflux tank is connected to the top gas phase outlet pipeline through a reflux pipeline and a top reflux pump, and the reflux pipeline downstream of the top reflux pump is connected to the inlet of the top reflux tank through a reflux branch pipe.

9. A hexane purified gas recovery system according to any one of claims 1 to 7, characterized in that: The bottom outlet of the hexane distillation tower is connected in sequence to a distillation tower bottom discharge pump, a bottom hexane cooler and a refined hexane adsorption purification tower through a bottom outlet pipeline.

10. A hexane purified gas recovery system according to any one of claims 1 to 7, characterized in that: A hexane refining reboiler is provided at the bottom of the hexane distillation tower.

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