Connecting structure of post-washing tower and refining tower of butadiene extractive distillation device
Patent Information
- Application Number
- CN202510455014.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-11
- Publication Date
- 2025-06-24
Smart Images
Figure CN120189723A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of butadiene production, and particularly to a connection structure between a post-washing tower and a refining tower of a butadiene extractive distillation device. Background Art
[0002] 1,3-butadiene ranks only second to ethylene and propylene in the industrial field and is one of the three major petrochemical olefin materials. Eighty percent of the world's 1,3-butadiene production is used to manufacture synthetic rubber; synthetic rubber has good elasticity, wear resistance, aging resistance, etc., and is widely used in the manufacture of products such as automobile tires, rubber hoses, and rubber belts. 1,3-butadiene can also be used to manufacture synthetic resins; synthetic resins have excellent mechanical properties, chemical corrosion resistance, insulation properties, etc., and are widely used in the fields of plastic products, coatings, adhesives, etc.
[0003] In known industrial plants, steam cracking for ethylene co-production, i.e., using naphtha, light diesel oil, etc. as raw materials and carrying out cracking reactions under high temperature and the presence of steam, is the main industrial source of 1,3-butadiene at present. During the cracking process, hydrocarbons in the raw materials undergo a series of complex chemical reactions to generate various products such as ethylene, propylene, and 1,3-butadiene. The advantages of this technology are wide raw material sources and mature technology; the disadvantages are large investment and complex product separation, and extractive distillation methods need to be used for rectification and purification.
[0004] At present, common 1,3-butadiene extractive distillation technologies mainly include the acetonitrile method (ACN method), the dimethylformamide method (DMF method), and the N-methylpyrrolidone method (NMP method). Among them, the acetonitrile solvent is highly toxic, and the dimethylformamide method has poor stability. The N-methylpyrrolidone method has excellent solvent properties, low toxicity, biodegradability, and low corrosiveness; the raw material range is relatively wide, high-quality butadiene can be obtained, and the product purity can reach more than 99.7%; the continuous on-line operation time of the device is long, and compared with similar processes, the solvent has strong anti-hydrolysis and thermal decomposition capabilities, and the solvent consumption can be reduced by more than 90%. Therefore, at present, the N-methylpyrrolidone method is mainly used for extractive distillation to prepare 1,3-butadiene. The production process mainly includes extractive distillation, degassing, distillation, and solvent regeneration processes. The crude C4 fraction is gasified and enters the bottom of the main washing tower, and the N-methylpyrrolidone extractant containing 8% water enters from the top of the tower. After a series of operations such as absorption, rectification, and degassing, 1,3-butadiene products are finally obtained from the top of the second distillation tower, and a small amount of solvent is regenerated to avoid impurity accumulation.
[0005] However, since the N-methylpyrrolidone extractive distillation method requires a series of rectification operations such as absorption, rectification, and degassing, including heating and cooling, the energy consumption of current industrial plants is relatively high. Therefore, how to reduce the energy consumption of the extractive distillation device is the goal that this technology needs to continue to optimize. Summary of the Invention
[0006] The object of the present invention is to provide a connection structure between the post-washing tower and the refining tower of a butadiene extractive distillation device, which can effectively reduce the equipment energy consumption and equipment load in the system.
[0007] The technical solution of the present invention to solve the above technical problems is: a connection structure between the post-washing tower and the refining tower of a butadiene extractive distillation device, including a post-washing tower and a butadiene refining tower. The bottom of the post-washing tower is connected to the side-line gas-phase input pipe of the upstream main washing and rectifying tower, and the upper part of the post-washing tower is connected to the lean extractant input pipe. The top of the post-washing tower is connected to the middle part of the butadiene refining tower through the gas-phase output pipe of the post-washing tower top, and a gas-phase input regulating valve of the butadiene refining tower is provided on the gas-phase output pipe of the post-washing tower top. The gas-phase output pipe of the post-washing tower top on the input side of the gas-phase input regulating valve of the butadiene refining tower is also connected to the input end of the post-washing tower condenser through the gas-phase input pipe of the post-washing tower condenser, and a gas-phase input regulating valve of the post-washing tower condenser is provided on the gas-phase input pipe of the post-washing tower condenser. The output end of the post-washing tower condenser is connected to the input end of the post-washing tower reflux drum.
[0008] The output end of the post-washing tower reflux drum is connected to the middle part of the butadiene refining tower through the liquid-phase input pipe of the butadiene refining tower, and a liquid-phase input regulating valve of the butadiene refining tower is provided on the liquid-phase input pipe of the butadiene refining tower. The liquid-phase input pipe of the butadiene refining tower on the input side of the liquid-phase input regulating valve of the butadiene refining tower is also connected to the post-washing tower above the lean extractant input pipe through the post-washing tower reflux pipe.
[0009] As a further improvement of the present invention, the top of the butadiene refining tower is connected to the input end of the butadiene refining tower condenser through the gas-phase output pipe of the butadiene refining tower top, and the output end of the butadiene refining tower condenser is connected to the input end of the butadiene refining tower reflux drum.
[0010] As a further improvement of the present invention, the output end of the butadiene refining tower reflux drum is connected to the upper part of the butadiene refining tower through the butadiene refining tower reflux pipe.
[0011] As a further improvement of the present invention, a liquid-phase pump is provided on the butadiene refining tower reflux pipe.
[0012] As a further improvement of the present invention, a reboiler is connected to the bottom of the butadiene refining tower through a pipeline.
[0013] As a further improvement of the present invention, the reboiler is a vertical thermosyphon reboiler.
[0014] As a further improvement of the present invention, a C4 / C5 output pipe is connected to the bottom of the butadiene refining tower.
[0015] As a further improvement of the present invention, a liquid-phase pump is further provided on the butadiene refining tower liquid-phase input pipe between the input end of the post-washing tower reflux pipe and the output end of the post-washing tower reflux tank.
[0016] As a further improvement of the present invention, the post-washing tower is an extractive distillation tower.
[0017] As a further improvement of the present invention, the butadiene refining tower is a plate distillation tower.
[0018] Beneficial effects
[0019] Compared with the prior art, the advantages of the connection structure between the post-washing tower and the refining tower of a butadiene extractive distillation device of the present invention are as follows:
[0020] 1. In this structure, through the regulation of the post-washing tower condenser gas-phase input regulating valve and the butadiene refining tower gas-phase input regulating valve, it is possible to reduce the flow rate of high-temperature gas-phase substances entering the post-washing tower condenser while increasing the flow rate of high-temperature gas-phase substances entering the butadiene refining tower, thereby reducing the energy consumption load of the cooling equipment, pumping equipment on the reflux line of the post-washing tower, and the heating equipment on the butadiene refining tower. Furthermore, the size of each device can also be reduced, reducing the investment in equipment.
[0021] Through the following description and in combination with the accompanying drawings, the present invention will become clearer. These drawings are used to explain the embodiments of the present invention. Brief description of the drawings
[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0023] Figure 1 It is a structural schematic diagram of the present invention.
[0024] Wherein: 1 - lean extractant input pipe; 2 - upstream main washing rectification tower side draw gas input pipe; 3 - post-washing tower; 4 - rich extractant output pipe; 5 - post-washing tower top gas output pipe; 6 - post-washing tower condenser gas input pipe; 7 - butadiene refining tower gas input regulating valve; 8 - post-washing tower condenser gas input regulating valve; 9 - post-washing tower condenser; 10 - post-washing tower reflux drum; 11 - butadiene refining tower liquid input regulating valve; 12 - butadiene refining tower liquid input pipe; 13 - post-washing tower reflux pipe; 14 - butadiene refining tower; 15 - butadiene refining tower top gas output pipe; 16 - butadiene refining tower condenser; 17 - butadiene refining tower reflux drum; 18 - butadiene refining tower reflux pipe; 19 - butadiene refining tower reboiler; 20 - C4 / C5 output pipe; 21 - liquid pump. Detailed implementation manners
[0025] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.
[0026] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; of course, it may also be a mechanical connection or an electrical connection; in addition, it may also be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0027] Now, embodiments of the present invention will be described with reference to the accompanying drawings.
[0028] Embodiment:
[0029] The detailed implementation manners of the present invention are as Figure 1 shown. A connection structure between the post-washing tower and the refining tower of a butadiene extractive distillation device includes a post-washing tower 3, a butadiene refining tower 14, and related reboiling and condensing systems. Among them, the bottom of the post-washing tower 3 is connected to the upstream main washing rectification tower side draw gas input pipe 2, the upper part of the post-washing tower 3 is connected to the lean extractant input pipe 1, and the bottom of the post-washing tower 3 is also connected to the rich extractant output pipe 4.
[0030] When the device is operating, the vapor side-drawn from the upstream main washing and rectifying column is used as the stripping steam of the post-washing column 3 and is input from the bottom of the post-washing column 3. Its main component is crude 1,3-butadiene with a mass percentage of 95%-98% obtained by extraction with the extractant N-methylpyrrolidone. Moreover, the vapor side-drawn from the upstream main washing and rectifying column also contains 1-butyne, butenyne, and 1,2-butadiene and cis-2-butene with similar solubilities. At the same time, the lean extractant is input from the upper part of the post-washing column 3 through the lean extractant input pipe 1. Its components include 85wt%-92wt% of N-methylpyrrolidone and 8wt%-15wt% of water, and its function is to absorb 1-butyne and butenyne in the vapor side-drawn from the upstream main washing and rectifying column. Finally, the rich extractant that has absorbed 1-butyne and butenyne is discharged from the rich extractant output pipe 4 at the bottom of the post-washing column 3 and sent to the upstream main washing and rectifying column. The remaining crude 1,3-butadiene in the gaseous state and a small amount of 1,2-butadiene and cis-2-butene are output from the top gas output pipe 5 of the post-washing column.
[0031] Regarding the pipeline setting between the post-washing column 3 and the butadiene refining column 14: The top of the post-washing column 3 is connected to the middle part of the butadiene refining column 14 through the top gas output pipe 5 of the post-washing column, and a butadiene refining column gas input regulating valve 7 is provided on the top gas output pipe 5 of the post-washing column. The top gas output pipe 5 on the input side of the butadiene refining column gas input regulating valve 7 is also connected to the input end of the post-washing column condenser 9 through the post-washing column condenser gas input pipe 6, and a post-washing column condenser gas input regulating valve 8 is provided on the post-washing column condenser gas input pipe 6. The output end of the post-washing column condenser 9 is connected to the input end of the post-washing column reflux drum 10.
[0032] Moreover, the output end of the post-washing column reflux drum 10 is connected to the middle part of the butadiene refining column 14 through the butadiene refining column liquid input pipe 12, and a butadiene refining column liquid input regulating valve 11 is provided on the butadiene refining column liquid input pipe 12. The butadiene refining column liquid input pipe 12 on the input side of the butadiene refining column liquid input regulating valve 11 is also connected to the post-washing column 3 above the lean extractant input pipe 1 through the post-washing column reflux pipe 13.
[0033] In this embodiment, the bottom of the butadiene refining column 14 is connected to a reboiler 19 through a pipeline, and the reboiler 19 provides heat for the butadiene refining column 14. Specifically, the reboiler 19 adopts a vertical thermosyphon heat exchanger, and the heat source is low-pressure steam. The reboiler 19 is a vertical thermosyphon reboiler, which has the advantages of good heat transfer effect and small floor area. At the same time, in order to pump the liquid product in the post-washing column reflux drum 10, a liquid pump 21 is also provided on the butadiene refining column liquid input pipe 12 between the input end of the post-washing column reflux pipe 13 and the output end of the post-washing column reflux drum 10.
[0034] With the above design, it is to reasonably utilize the heat carried by the gas-phase product in the gas-phase output pipe 5 at the top of the post-wash tower. Specifically: The gas-phase product in the gas-phase output pipe 5 at the top of the post-wash tower is divided into two parts. One part directly enters the butadiene refining tower 14 through the gas-phase input regulating valve 7 of the butadiene refining tower. The other part enters the post-wash tower condenser 9 through the gas-phase input regulating valve 8 of the post-wash tower condenser. In the post-wash tower condenser 9, the gas-phase product is cooled to a liquid phase by circulating water and then enters the post-wash tower reflux drum 10. After that, the liquid-phase effluent of the post-wash tower reflux drum 10 is again divided into two parts. One part returns to the post-wash tower 3 through the post-wash tower reflux pipe 13. The other part is sent to the middle of the butadiene refining tower 14 after the flow rate is adjusted by the butadiene refining tower liquid-phase input regulating valve 11.
[0035] With such a design, as long as the reflux requirement of the post-wash tower 3 is met, it will have no impact on the stable operation of this tower. At the same time, this can also reduce the flow rate of the high-temperature gas-phase substances entering the post-wash tower condenser 9, thereby greatly reducing the flow rate entering the post-wash tower condenser 9 and the liquid-phase pump 21 at this place. Furthermore, not only can the consumption of circulating water in the post-wash tower condenser 9 and the energy consumption of the liquid-phase pump 21 be reduced, but also the sizes of the post-wash tower condenser 9, the liquid-phase pump 21 and other corresponding equipment can be reduced, reducing the equipment investment. And this design can also increase the flow rate of the high-temperature gas-phase substances entering the butadiene rectification tower 14, thereby not only reducing the heat load of the reboiler 19 on the butadiene rectification tower 14, but also reducing the size of the reboiler 19, and further reducing the equipment investment.
[0036] In addition, regarding the other pipeline settings on the butadiene refining tower 14: The top of the butadiene refining tower 14 is connected to the input end of the butadiene refining tower condenser 16 through the butadiene refining tower top gas-phase output pipe 15. The output end of the butadiene refining tower condenser 16 is connected to the input end of the butadiene refining tower reflux drum 17. The output end of the butadiene refining tower reflux drum 17 is connected to the upper part of the butadiene refining tower 14 through the butadiene refining tower reflux pipe 18. In this embodiment, a liquid-phase pump 21 is provided on the butadiene refining tower reflux pipe 18. At the same time, a C4 / C5 output pipe 20 is connected to the bottom of the butadiene refining tower 14.
[0037] The main purpose of the butadiene refining tower 14 is to remove a small amount of 1,2-butadiene and cis-2-butene to meet the purity standard of the 1,3-butadiene product. Specifically: through the rectification of the butadiene refining tower 14, 1,2-butadiene, cis-2-butene and a small amount of C5+ mixture are obtained at the bottom of the butadiene refining tower 14, and this mixture is discharged from the C4 / C5 output pipe 20; at the same time, the overhead gas product of the butadiene refining tower 14 is the 1,3-butadiene product. The overhead gas product of the butadiene refining tower 14 is led out from the top of the tower and fed into the butadiene refining tower condenser 16, where the gaseous 1,3-butadiene product is cooled to the liquid phase by circulating water. Subsequently, it flows by gravity into the butadiene refining tower reflux drum 17. After the butadiene refining tower reflux drum 17 is connected to the butadiene refining tower reflux pipe 18 through the liquid-phase pump 21, part of the liquid-phase 1,3-butadiene returns to the butadiene refining tower 14, and part of the liquid-phase 1,3-butadiene is sent as a product to the downstream.
[0038] In this embodiment, it should be noted that:
[0039] The post-washing tower 3 is an extractive distillation tower, with packing internals at the lower part and a plate tower structure at the upper part; and the operating pressure at the top of the post-washing tower 3 is 0.3 MPag - 0.6 MPag, and the operating temperature at the top is 45°C - 60°C. The butadiene distillation tower 14 is a plate distillation tower, with an operating pressure of 0.25 MPag - 0.5 MPag and a bottom operating temperature of 50°C - 65°C. Therefore, the gas-phase stream at the top of the post-washing tower 3 can flow by gravity into the butadiene refining tower 14 without additional pressurization equipment.
[0040] In addition, in order to facilitate the understanding of the effective reduction of the equipment energy consumption and equipment load in this system, the following three comparative examples are specifically proposed:
[0041] Comparative Example 1:
[0042] In this example, taking the annual output of 250,000 tons of 1,3-butadiene product as an example. As Figure 1 shown, the side-stream extract gas from the upstream main washing and rectifying tower is about 68.9 t / h, among which, it contains 96.7 wt% of 1,3-butadiene, 0.53 wt% of cis-2-butene, 1.34 wt% of 1,2-butadiene, and the total of 1-butyne and butenyne is 0.3 wt%, and the rest are C5 and the extractant aqueous solution. This side-stream extract enters the bottom of the post-washing tower 3. At the same time, the lean extractant is about 150 t / h, among which, it contains 92 wt% of N-methylpyrrolidone, 8 wt% of water, and the temperature is 40°C, and it enters the upper part of the post-washing tower 3 to contact the side-stream extract gas from the upstream main washing and rectifying tower countercurrently.
[0043] In the post-washing tower 3, 1-butyne and butenyne, which are more soluble in the extractant, are absorbed by the extractant and then discharged from the bottom of the tower. The main components of the gas phase at the top of the post-washing tower 3 are 1,3-butadiene, cis-2-butene, 1,2-butadiene, as well as trace amounts of water and C5, approximately 51 t / h.
[0044] In this embodiment, the operating pressure of the post-washing tower 3 is 0.4 MpaG, and the temperature of the gas phase at the top of the tower is 47°C. Subsequently, the gas phase at the top of the tower is divided into two streams. The mass flow rate of the gas-phase stream going to the butadiene refining tower 14 is 15 t / h, and the mass flow rate of the gas-phase stream going to the condenser 9 of the post-washing tower is 36 t / h. The gas-phase stream going to the condenser 9 of the post-washing tower is cooled to 45°C by circulating cooling water and then becomes a liquid phase. Part of the liquid with a mass flow rate of 19 t / h is used as the reflux of the post-washing tower 3; the other part of the liquid with a mass flow rate of 17 t / h enters the butadiene refining tower 14 as a liquid-phase feed.
[0045] The butadiene refining tower 14 has a plate tower structure. In this embodiment, the actual number of trays is set to 90. The operating pressure of the butadiene refining tower 14 is 0.37 MPag, and the operating temperature at the bottom of the tower is 55°C. The above-mentioned gas-phase feed and liquid-phase feed to the butadiene refining tower 14 enter the butadiene refining tower 14 from the 50th tray. In this tower, ordinary distillation of 1,3-butadiene, cis-2-butene, 1,2-butadiene, as well as trace amounts of water and C5 is mainly carried out. 1,3-butadiene with a relatively low boiling point is obtained at the top of the tower, and cis-2-butene, 1,2-butadiene, and trace amounts of C5 are at the bottom of the tower. The top reflux of the butadiene refining tower 14 is provided with cooling capacity by circulating cooling water; the reboiler 19 at the bottom of the tower uses a vertical thermosyphon reboiler, and heat is provided by low-pressure steam. In this embodiment, the 1,3-butadiene product taken out from the top of the tower is 31.5 t / h, with a purity of 99.8 wt%, meeting the requirements of national standards.
[0046] Comparative Example 2:
[0047] In this example, the mass flow rate of the gas-phase stream going to the butadiene refining tower 14 is 7 t / h, and the mass flow rate of the gas-phase stream going to the condenser 9 of the post-washing tower is 44 t / h. This stream is cooled to 45°C by circulating cooling water and then becomes a liquid phase. Part of the liquid with a mass flow rate of 19 t / h is used as the reflux of the post-washing tower 3; the other part of the liquid with a mass flow rate of 25 t / h enters the butadiene refining tower 14 as a liquid-phase feed. The remaining operating conditions are the same as those in the previous example.
[0048] Comparative Example 3:
[0049] In this comparative example, the mass flow rate of the gas-phase stream directly going to the butadiene refining tower 14 is 0, and the post-washing tower 3 operates in a total reflux mode, that is, all the gas-phase products at the top of the tower enter the condenser 9 of the post-washing tower. At this time, all the feeds to the butadiene refining tower 14 are in the liquid phase. The remaining operating conditions remain unchanged.
[0050] By comparing Comparative Examples 1-3, the following record table can be obtained. Specifically, this table is a comparison table of the circulating water consumption, low-pressure steam consumption, and equipment dimensions in Comparative Example 1, Comparative Example 2, and Comparative Example 3.
[0051] Comparative Example 1 Comparative Example 2 Comparative Example 3 Circulating water consumption of the post-washing tower condenser 9 t / h (30°C - 38°C) 400 490 570 Low-pressure steam consumption of the reboiler 19 t / h 17.5 18.8 20.2 Power consumption of the liquid-phase pump 21 of the post-washing tower 3 kwh 14.6 17.8 20.7 <![CDATA[Rear scrubber condenser 9 heat transfer area m 2 > 900 1150 1380 <![CDATA[Reboiler 19 heat transfer area m 2 > 310 330 360
[0052] As can be seen from the above table, the greater the flow rate of the top gas phase stream of the post-washing tower 3 directly going to the butadiene refining tower 14, the smaller the low-pressure steam consumption and the smaller the circulating cooling water consumption. Compared with Comparative Example 1 and Comparative Example 3, the low-pressure steam consumption is reduced by 2.7 t / h, the circulating cooling water consumption is reduced by 181 t / h, and the power consumption of the liquid-phase pump 21 of the post-washing tower 3 is reduced by 6.1 kwh. At the same time, the heat transfer area of the post-washing tower condenser 9 is reduced by 490 m 2 , and the heat transfer area of the reboiler 19 is reduced by 50 m 2 , which also indicates a reduction in the size of the heat exchanger and a decrease in equipment investment.
[0053] The present invention has been described in combination with the best embodiments, but the present invention is not limited to the disclosed embodiments above, and should cover various modifications and equivalent combinations made according to the essence of the present invention.
Claims
1. A connection structure of a post-wash tower and a refining tower of a butadiene extraction and distillation device, comprising a post-wash tower (3) and a butadiene refining tower (14), characterized in that: The tower kettle of the post-wash tower (3) is connected to the side line gas phase input pipe (2) of the upstream main wash distillation tower, and the upper part of the post-wash tower (3) is connected to the lean extractant input pipe (1); the top of the post-wash tower (3) is connected to the middle part of the butadiene refining tower (14) through the post-wash tower top gas phase output pipe (5), and the post-wash tower top gas phase output pipe (5) is provided with a butadiene refining tower gas phase input regulating valve (7), the post-wash tower top gas phase output pipe (5) on the input side of the butadiene refining tower gas phase input regulating valve (7) is also connected to the input end of the post-wash tower condenser (9) through the post-wash tower condenser gas phase input pipe (6), and the post-wash tower condenser gas phase input regulating valve (8) is provided on the post-wash tower condenser gas phase input pipe (6), and the output end of the post-wash tower condenser (9) is connected to the input end of the post-wash tower reflux tank (10); The output end of the post-wash tower reflux tank (10) is connected to the middle of the butadiene refining tower (14) through a butadiene refining tower liquid phase input pipe (12), and a butadiene refining tower liquid phase input regulating valve (11) is provided on the butadiene refining tower liquid phase input pipe (12). The butadiene refining tower liquid phase input pipe (12) on the input side of the butadiene refining tower liquid phase input regulating valve (11) is also connected to the post-wash tower (3) above the lean extractant input pipe (1) through a post-wash tower reflux pipe (13).
2. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 1, characterized in that: The top of the butadiene refining tower (14) is connected to the input end of the butadiene refining tower condenser (16) through the butadiene refining tower top gas phase output pipe (15), and the output end of the butadiene refining tower condenser (16) is connected to the input end of the butadiene refining tower reflux tank (17).
3. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 2 is characterized in that: The output end of the butadiene refining tower reflux tank (17) is connected to the upper part of the butadiene refining tower (14) through a butadiene refining tower reflux pipe (18).
4. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 3 is characterized in that: The butadiene refining tower reflux pipe (18) is provided with a liquid phase pump (21).
5. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 1 is characterized in that: The bottom of the butadiene refining tower (14) is connected to a reboiler (19) via a pipeline.
6. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 5, characterized in that: The reboiler (19) is a vertical thermosyphon reboiler.
7. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 1, characterized in that: The bottom of the butadiene refining tower (14) is connected to a C4 / C5 output pipe (20).
8. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 1, characterized in that: A liquid phase pump (21) is also provided on the butadiene refining tower liquid phase input pipe (12) between the input end of the post-wash tower reflux pipe (13) and the output end of the post-wash tower reflux tank (10).
9. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 1, characterized in that: The post-wash tower (3) is an extractive distillation tower.
10. The connection structure of the post-wash tower and the refining tower of the butadiene extraction and distillation device according to claim 1, characterized in that: The butadiene distillation tower (14) is a plate-type distillation tower.