Connecting structure of post-washing tower and refining tower of butadiene extractive distillation device
By optimizing the connection structure between the post-washing tower and the refining tower, and utilizing the heat of the gaseous products, the energy consumption of cooling and heating equipment is reduced, thus solving the problem of high energy consumption in the butadiene extraction distillation unit and achieving a reduction in equipment energy consumption and investment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-11
- Publication Date
- 2026-03-17
AI Technical Summary
Existing butadiene extractive distillation units have high energy consumption and need to be optimized to reduce equipment energy consumption and load.
Design a connection structure between the post-washing column and the purification column of a butadiene extraction distillation device. By using a regulating valve and a condenser in combination, reduce the flow rate of high-temperature gaseous material entering the condenser and increase the flow rate of high-temperature gaseous material entering the purification column, make reasonable use of the heat of gaseous products, and reduce the energy consumption of cooling and heating equipment.
It reduces the energy load of cooling and heating equipment in the post-washing and refining towers, reduces equipment size, and lowers equipment investment and energy consumption.
Smart Images
Figure CN223995434U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of butadiene production technology, and in particular to a connection structure between the post-washing tower and the refining tower of a butadiene extractive distillation apparatus. Background Technology
[0002] 1,3-Butadiene holds a significant position in the industrial sector, second only to ethylene and propylene, 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 possesses excellent elasticity, abrasion resistance, and aging resistance, 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 artificial resins; artificial resins possess excellent mechanical properties, chemical corrosion resistance, and insulation properties, and are widely used in plastic products, coatings, adhesives, and other fields.
[0003] In known industrial plants, steam cracking for ethylene co-production—using naphtha, light diesel oil, etc., as feedstock and undergoing cracking reactions under high temperature and steam conditions—is currently the main industrial source of 1,3-butadiene. During the cracking process, the hydrocarbons in the feedstock undergo a series of complex chemical reactions to produce various products such as ethylene, propylene, and 1,3-butadiene. The advantages of this technology are its wide availability of feedstocks and mature technology; the disadvantages are high investment costs and complex product separation, requiring extraction distillation for purification.
[0004] Currently, 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 these, acetonitrile solvent is highly toxic, and the DMF method has poor stability. In contrast, the N-methylpyrrolidone method offers excellent solvent performance, low toxicity, biodegradability, and low corrosivity; it has a wide range of feedstocks, yields high-quality butadiene with a purity exceeding 99.7%; and the equipment can operate continuously online for extended periods. Compared to similar processes, the solvent exhibits strong resistance to hydrolysis and thermal decomposition, reducing solvent consumption by over 90%. Therefore, the N-methylpyrrolidone method is currently the primary method for preparing 1,3-butadiene through extractive distillation. The production process mainly includes extractive distillation, degassing and distillation, and solvent regeneration. After the crude C4 fraction is vaporized, it enters the bottom of the main washing column. The N-methylpyrrolidone extractant containing 8% water enters from the top of the column. After a series of absorption, distillation, degassing and other operations, the 1,3-butadiene product is finally obtained from the top of the second distillation column. At the same time, a small amount of solvent is regenerated to avoid the accumulation of impurities.
[0005] However, because the N-methylpyrrolidone extractive distillation method requires a series of heating and cooling operations, including absorption, distillation, and degassing, current industrial-scale plants consume a relatively high amount of energy. Therefore, reducing the energy consumption of extractive distillation units is a goal that needs further optimization for this technology. Utility Model Content
[0006] The purpose of this invention is to provide a connection structure between the post-washing tower and the purification tower of a butadiene extraction distillation apparatus, which can effectively reduce the energy consumption and equipment load of the system.
[0007] The technical solution of this utility model to solve the above-mentioned technical problems is: a connection structure between a post-washing tower and a refining tower in a butadiene extractive distillation apparatus, 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 distillation tower, and the upper part of the post-washing tower is connected to a lean extractant input pipe. The bottom of the post-washing tower is also connected to a rich extractant output pipe. The top of the post-washing tower is connected to the middle part of the butadiene refining tower through a post-washing tower top gas phase output pipe. A butadiene refining tower gas phase input regulating valve is provided on the post-washing tower top gas phase output pipe. The post-washing tower top gas phase output pipe on the input side of the butadiene refining tower gas phase input regulating valve is also connected to the input end of the post-washing tower condenser through a post-washing tower condenser gas phase input pipe. A post-washing tower condenser gas phase input regulating valve is provided on the post-washing tower condenser gas phase input pipe. The output end of the post-washing tower condenser is connected to the input end of the post-washing tower reflux tank.
[0008] The output end of the post-wash tower reflux tank is connected to the middle of the butadiene refining tower through the butadiene refining tower liquid phase input pipe, and the butadiene refining tower liquid phase input regulating valve is provided on the butadiene refining tower liquid phase input pipe. The butadiene refining tower liquid phase input pipe on the input side of the butadiene refining tower liquid phase input regulating valve is also connected to the post-wash tower above the lean extractant input pipe through the post-wash tower reflux pipe.
[0009] As a further improvement of this utility model, the top of the butadiene refining tower is connected to the input end of the butadiene refining tower condenser via the top gas phase output pipe of the butadiene refining tower, and the output end of the butadiene refining tower condenser is connected to the input end of the butadiene refining tower reflux tank.
[0010] As a further improvement of this utility model, the output end of the butadiene refining tower reflux tank is connected to the upper part of the butadiene refining tower through the butadiene refining tower reflux pipe.
[0011] As a further improvement of this utility model, a liquid phase pump is provided on the reflux pipe of the butadiene refining tower.
[0012] As a further improvement of this utility model, the butadiene refining tower bottom is connected to a reboiler via a pipeline.
[0013] As a further improvement of this utility model, the reboiler is a vertical thermosiphon reboiler.
[0014] As a further improvement of this utility model, the butadiene refining tower is connected to a C4 / C5 output pipe.
[0015] As a further improvement of this utility model, a liquid phase pump is also provided on the butadiene refining tower liquid phase input pipe between the input end of the post-wash tower reflux pipe and the output end of the post-wash tower reflux tank.
[0016] As a further improvement of this utility model, the post-washing tower is an extractive distillation tower.
[0017] As a further improvement of this utility model, the butadiene distillation column is a plate distillation column.
[0018] Beneficial effects
[0019] Compared with the prior art, the advantages of the connection structure between the post-washing column and the purification column of the butadiene extraction distillation apparatus of this utility model are as follows:
[0020] 1. In this structure, by regulating the gas phase input valve of the post-wash tower condenser and the gas phase input valve of the butadiene refining tower, the flow rate of high-temperature gas phase entering the post-wash tower condenser can be reduced while the flow rate of high-temperature gas phase entering the butadiene distillation tower can be increased. This reduces the energy load of the cooling equipment, pumping equipment on the reflux line of the post-wash tower and the heating equipment on the butadiene distillation tower. Furthermore, it can reduce the size of each piece of equipment and lower the investment in the equipment.
[0021] The present invention will become clearer from the following description and in conjunction with the accompanying drawings, which are used to explain the embodiments of the present invention. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of the structure of this utility model.
[0024] Wherein: 1-Lean extractant inlet pipe; 2-Upstream main wash distillation column side stream gas phase inlet pipe; 3-Post wash column; 4-Rich extractant outlet pipe; 5-Post wash column top gas phase outlet pipe; 6-Post wash column condenser gas phase inlet pipe; 7-Butadiene refining column gas phase inlet regulating valve; 8-Post wash column condenser gas phase inlet regulating valve; 9-Post wash column condenser; 10-Post wash column reflux tank; 11-Butadiene refining column liquid phase inlet regulating valve; 12-Butadiene refining column liquid phase inlet pipe; 13-Post wash column reflux pipe; 14-Butadiene refining column; 15-Butadiene refining column top gas phase outlet pipe; 16-Butadiene refining column condenser; 17-Butadiene refining column reflux tank; 18-Butadiene refining column reflux pipe; 19-Butadiene refining column reboiler; 20-C4 / C5 outlet pipe; 21-Liquid phase pump. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model 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 this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.
[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; of course, they can also refer to a mechanical connection or an electrical connection; furthermore, they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0027] Embodiments of the present invention will now be described with reference to the accompanying drawings.
[0028] Example:
[0029] The specific embodiments of this utility model are as follows: Figure 1 As shown, a connection structure between a post-wash column and a purification column in a butadiene extractive distillation apparatus includes a post-wash column 3, a butadiene purification column 14, and related reboiling and condensation systems. The bottom of the post-wash column 3 is connected to the side-stream gas phase input pipe 2 of the upstream main wash distillation column, the upper part of the post-wash column 3 is connected to a lean extractant input pipe 1, and the bottom of the post-wash column 3 is also connected to a rich extractant output pipe 4.
[0030] During operation, the vapor phase from the upstream main wash distillation column is used as stripping steam for the downstream wash column 3 and is fed into the bottom of the downstream wash 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. The vapor phase from the upstream main wash distillation column also contains 1-butyne, butenyne, and 1,2-butadiene and cis-2-butene, which have similar solubility. Simultaneously, a lean extractant is introduced from the top of the downstream wash column 3 through the lean extractant inlet pipe 1. Its components include 85wt%-92wt% methylpyrrolidone and 8wt%-15wt% water, and its function is to absorb the 1-butyne and butenyne in the vapor phase from the upstream main wash distillation 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 tower 3 and sent to the upstream main washing distillation tower. The remaining crude 1,3-butadiene in gaseous form, as well as a small amount of 1,2-butadiene and cis-2-butene, are output from the gas phase output pipe 5 at the top of the post-washing tower.
[0031] Regarding the piping arrangement between the post-wash tower 3 and the butadiene refining tower 14: the top of the post-wash tower 3 is connected to the middle of the butadiene refining tower 14 via the post-wash tower top gas phase output pipe 5, and a butadiene refining tower gas phase input regulating valve 7 is installed on the post-wash tower top gas phase output pipe 5. 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 via the post-wash tower condenser gas phase input pipe 6, and a post-wash tower condenser gas phase input regulating valve 8 is installed on the post-wash tower condenser gas phase input pipe 6. The output end of the post-wash tower condenser 9 is connected to the input end of the post-wash tower reflux tank 10.
[0032] Furthermore, the output end of the post-wash tower reflux tank 10 is connected to the middle of the butadiene refining tower 14 via the butadiene refining tower liquid phase input pipe 12, and the butadiene refining tower liquid phase input pipe 12 is equipped with a butadiene refining tower liquid phase input regulating valve 11. 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 via the post-wash tower reflux pipe 13.
[0033] In this embodiment, the butadiene refining column 14 is connected to a reboiler 19 via a pipeline, which provides heat to the butadiene refining column 14. Specifically, the reboiler 19 is a vertical thermosiphon heat exchanger, using low-pressure steam as the heat source. This vertical thermosiphon reboiler 19 has the advantages of good heat transfer and small footprint. Meanwhile, to pump the liquid phase product in the post-wash column reflux tank 10, a liquid phase pump 21 is also installed on the butadiene refining column liquid phase input pipe 12 between the input end of the post-wash column reflux pipe 13 and the output end of the post-wash column reflux tank 10.
[0034] The above design is adopted to make reasonable use of the heat carried by the gaseous products in the gas phase output pipe 5 at the top of the post-washing tower. Specifically, the gaseous products in the gas phase output pipe 5 at the top of the post-washing tower are divided into two parts. One part enters the butadiene refining tower 14 directly through the gas phase input regulating valve 7. The other part enters the post-washing tower condenser 9 through the gas phase input regulating valve 8. In the post-washing tower condenser 9, the gaseous products are cooled into liquid phase by circulating water and then enter the post-washing tower reflux tank 10. Afterwards, the liquid effluent from the post-washing tower reflux tank 10 is divided into two parts. One part returns to the post-washing tower 3 through the post-washing tower reflux pipe 13. The other part, after its flow rate is regulated by the butadiene refining tower liquid phase input regulating valve 11, is sent to the middle part of the butadiene refining tower 14.
[0035] This design, by simply meeting the return flow requirements of the post-wash tower 3, will not affect the stable operation of the tower. Simultaneously, it reduces the flow rate of high-temperature gaseous phase entering the post-wash tower condenser 9, thereby significantly reducing the flow rate entering the condenser 9 and the liquid phase pump 21 there. This not only reduces the consumption of circulating water in the post-wash tower condenser 9 and the energy consumption of the liquid phase pump 21, but also allows for a reduction in the size of the post-wash tower condenser 9, liquid phase pump 21, and other related equipment, thus lowering equipment investment. Furthermore, this design increases the flow rate of high-temperature gaseous phase entering the butadiene distillation tower 14, thereby reducing the heat load on the reboiler 19 in the butadiene distillation tower 14 and allowing for a reduction in the size of the reboiler 19, further lowering equipment investment.
[0036] In addition, regarding the remaining piping configuration of the butadiene refining column 14: the top of the butadiene refining column 14 is connected to the input end of the butadiene refining column condenser 16 via the top gas phase output pipe 15. The output end of the butadiene refining column condenser 16 is connected to the input end of the butadiene refining column reflux tank 17. The output end of the butadiene refining column reflux tank 17 is connected to the upper part of the butadiene refining column 14 via the butadiene refining column reflux pipe 18. In this embodiment, a liquid phase pump 21 is installed on the butadiene refining column reflux pipe 18. Simultaneously, a C4 / C5 output pipe 20 is connected to the bottom of the butadiene refining column 14.
[0037] The main purpose of butadiene refining column 14 is to remove small amounts of 1,2-butadiene and cis-2-butene, ensuring the purity of the 1,3-butadiene product meets the required standards. Specifically, through distillation in butadiene refining column 14, the bottom of column 14 yields a mixture of 1,2-butadiene, cis-2-butene, and a small amount of C5+, which is discharged from the C4 / C5 outlet pipe 20. Simultaneously, the overhead vapor product of butadiene refining column 14 is 1,3-butadiene. This overhead vapor product is drawn from the top of column 14 and fed into butadiene refining column condenser 16, where the vapor 1,3-butadiene product is cooled to the liquid phase by circulating water. It then flows by gravity into butadiene refining column reflux tank 17. After the butadiene refining tower reflux tank 17 is connected to the butadiene refining tower reflux pipe 18 via the liquid phase pump 21, part of the liquid phase of 1,3-butadiene returns to the butadiene refining tower 14, and part of the liquid phase of 1,3-butadiene is sent downstream as a product.
[0038] In this embodiment, it is important to note that:
[0039] The post-wash column 3 is an extractive distillation column, with packed internals in the lower section and a plate column structure in the upper section. The operating pressure at the top of the post-wash column 3 is 0.3 MPa-0.6 MPa, and the operating temperature at the top is 45℃-60℃. The butadiene distillation column 14 is a plate distillation column with an operating pressure of 0.25 MPa-0.5 MPa and a bottom operating temperature of 50℃-65℃. Therefore, the vapor stream from the top of the post-wash column 3 can flow by gravity into the butadiene refining column 14 without the need for additional pressurization equipment.
[0040] In addition, to facilitate understanding of how this system effectively reduces equipment energy consumption and load, the following three comparative examples are specifically presented:
[0041] Comparative Example 1:
[0042] In this example, we take an annual production capacity of 250,000 tons of 1,3-butadiene as an example. Figure 1 As shown, approximately 68.9 t / h of the gas phase from the upstream main wash distillation column side stream is produced, containing 96.7 wt% 1,3-butadiene, 0.53 wt% cis-2-butene, 1.34 wt% 1,2-butadiene, and 0.3 wt% 1-butyne and butenyne combined, with the remainder being C5 atoms and an aqueous extractant solution. This side stream enters the bottom of the post-wash column 3. Simultaneously, approximately 150 t / h of lean extractant, containing 92 wt% methylpyrrolidone and 8 wt% water at 40°C, enters the upper part of the post-wash column 3, where it comes into countercurrent contact with the gas phase from the upstream main wash distillation column side stream.
[0043] In post-wash 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 post-wash tower 3 are 1,3-butadiene, cis-2-butene, 1,2-butadiene, and trace amounts of water and C5, approximately 51 t / h.
[0044] In this embodiment, the operating pressure of the post-wash tower 3 is 0.4 MPaG, and the gas phase temperature at the top of the tower is 47°C. The gas phase at the top of the tower is then divided into two streams. The gas phase stream flowing to the butadiene refining tower 14 has a mass flow rate of 15 t / h, and the gas phase stream flowing to the post-wash tower condenser 9 has a mass flow rate of 36 t / h. The gas phase stream flowing to the post-wash tower condenser 9 is cooled to 45°C by circulating cooling water and becomes a liquid phase. A portion of the liquid, with a mass flow rate of 19 t / h, is used as reflux for the post-wash tower 3; the other portion, with a mass flow rate of 17 t / h, is fed into the butadiene refining tower 14 as liquid feed.
[0045] The butadiene refining column 14 is a plate column structure; in this embodiment, the actual number of plates is set to 90. The operating pressure of the butadiene refining column 14 is 0.37 MPa, and the reboiler operating temperature is 55°C. The gaseous and liquid feeds to the butadiene refining column 14 enter from the 50th plate. In this column, the main processes are the conventional distillation of 1,3-butadiene, cis-2-butene, 1,2-butadiene, and trace amounts of water and C5. The top of the column yields 1,3-butadiene with a relatively low boiling point, while the bottom contains cis-2-butene, 1,2-butadiene, and trace amounts of C5. The reflux at the top of the butadiene refining column 14 is cooled by circulating cooling water; the reboiler 19 in the reboiler is a vertical thermosiphon reboiler, heated by low-pressure steam. In this embodiment, the 1,3-butadiene product extracted from the top of the tower is 31.5 t / h with a purity of 99.8 wt%, which meets the requirements of national standards.
[0046] Comparative Example 2:
[0047] In this example, the gas stream from butadiene refining tower 14 has a mass flow rate of 7 t / h, and the gas stream from the post-wash tower condenser 9 has a mass flow rate of 44 t / h. This stream is cooled to 45°C by circulating cooling water and becomes liquid. A portion of this liquid (19 t / h mass flow rate) is used as reflux to post-wash tower 3; the remaining portion (25 t / h mass flow rate) is fed into butadiene refining tower 14 as liquid feed. The remaining operating conditions are the same as in the previous example.
[0048] Comparative Example 3:
[0049] In this comparative example, the mass flow rate of the gas stream directly into butadiene refining tower 14 is 0. The post-wash tower 3 operates in full reflux mode, meaning that all the gaseous product from the top of the tower enters the condenser 9 of the post-wash tower. At this time, butadiene refining tower 14 is entirely fed with liquid. All other operating conditions remain unchanged.
[0050] Through Comparative Examples 1-3, the following record table can be obtained. Specifically, this table is a comparison table of circulating water consumption, low-pressure steam consumption, and equipment dimensions in Comparative Examples 1, 2, and 3.
[0051] Comparative Example 1 Comparative Example 2 Comparative Example 3 Post-wash tower condenser 9 circulating water consumption t / h (30℃-38℃) 400 490 570 Reboiler 19 Low-pressure steam consumption t / h 17.5 18.8 20.2 The power consumption of the liquid phase pump 21 in post-washing tower 3 is kWh. 14.6 17.8 20.7 <![CDATA[Condenser 9 of the post-washing tower, 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 table above, the higher the flow rate of the vapor stream from the top of the post-wash tower 3 directly to the butadiene refining tower 14, the lower the low-pressure steam consumption and the lower the circulating cooling water consumption. Compared with Comparative Example 3, Comparative Example 1 shows a reduction of 2.7 t / h in low-pressure steam consumption, a reduction of 181 t / h in circulating cooling water consumption, and a reduction of 6.1 kWh in the power consumption of the liquid phase pump 21 in post-wash tower 3. Simultaneously, the heat exchange area of the post-wash tower condenser 9 is reduced by 490 m². 2 The heat exchange area of reboiler 19 was reduced by 50m². 2 This also indicates that the size of the heat exchanger will be reduced, and the equipment investment will be lower.
[0053] The present invention has been described above in conjunction with the preferred embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations made in accordance with the essence of the present invention.
Claims
1. A connecting structure of a finishing column and a polishing column of a butadiene extractive rectification apparatus, comprising a polishing column (3) and a butadiene finishing column (14), characterized in that, The tower kettle of the afterwashing tower (3) is connected with the side line produced gas phase input pipe (2) of the upstream main washing rectifying tower, and the upper part of the afterwashing tower (3) is connected with the lean extractant input pipe (1), and the bottom of the afterwashing tower (3) is also connected with the rich extractant output pipe (4); the top of the afterwashing tower (3) is connected with the middle part of the butadiene refining tower (14) through the afterwashing tower top gas phase output pipe (5), and the butadiene refining tower gas phase input adjusting valve (7) is arranged on the afterwashing tower top gas phase output pipe (5); the afterwashing tower top gas phase output pipe (5) on the input side of the butadiene refining tower gas phase input adjusting valve (7) is also connected with the input end of the afterwashing tower condenser (9) through the afterwashing tower condenser gas phase input pipe (6), and the afterwashing tower condenser gas phase input adjusting valve (8) is arranged on the afterwashing tower condenser gas phase input pipe (6); the output end of the afterwashing tower condenser (9) is connected with the input end of the afterwashing tower reflux tank (10); The output end of the afterwashing tower reflux tank (10) is connected with the middle part of the butadiene refining tower (14) through the butadiene refining tower liquid phase input pipe (12), and the butadiene refining tower liquid phase input adjusting valve (11) is arranged 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 adjusting valve (11) is also connected with the afterwashing tower (3) above the lean extractant input pipe (1) through the afterwashing tower reflux pipe (13).
2. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 1, characterized by The top of the butadiene refining tower (14) is connected with the input end of the butadiene refining tower condenser (16) through the butadiene refining tower top gas phase output pipe (15).
3. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 2, characterized by The output end of the butadiene refining tower reflux tank (17) is connected with the upper part of the butadiene refining tower (14) through the butadiene refining tower reflux pipe (18).
4. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 3, characterized by A liquid phase pump (21) is arranged on the butadiene refining tower reflux pipe (18).
5. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 1, characterized by The tower kettle of the butadiene refining tower (14) is connected with the reboiler (19) through a pipeline.
6. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 5, wherein The reboiler (19) is a vertical thermosyphon reboiler.
7. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 1, characterized by The tower kettle of the butadiene refining tower (14) is connected with the C4 / C5 output pipe (20).
8. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 1, characterized by A liquid phase pump (21) is further arranged on the butadiene refining tower liquid phase input pipe (12) between the input end of the afterwashing tower reflux pipe (13) and the output end of the afterwashing tower reflux tank (10).
9. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 1, characterized by The afterwashing tower (3) is an extractive rectifying tower.
10. The connecting structure of the post washing column and the refining column of the butadiene extractive rectification apparatus according to claim 1, characterized by The butadiene refining tower (14) is a plate type rectifying tower.