Process and system for continuous rectification and recovery of 1, 2-butadiene

Abstract

The invention provides a continuous rectification recovery process of 1, 2-butadiene, which comprises the following steps: preheating a heavy C4 raw material and an extraction agent, feeding the preheated heavy C4 raw material and extraction agent into an extractive distillation tower, steaming out a light component A from the tower top, condensing, and returning to the tower top as reflux; the heavy component A is rectified in an extractant separation tower, a light component B is distilled out from the tower top, part of the light component B returns to serve as reflux, and the other part of the light component B enters a heavy component removal tower; the heavy component B returns to the extractive distillation tower through the heat exchanger. After heavy components of the light component B are removed in the heavy component removal tower, the light component C is evaporated out from the tower top, condensed and fed into a 1, 2-butadiene storage tank. And the heavy component C finally flows into a waste liquid tank. Wherein the heavy C4 raw material and the extraction agent are preheated by a heat exchanger, and the heat exchanger uses the heavy component B as a heat source. By providing a simple, feasible, economical and efficient continuous extractive distillation process, high-purity 1, 2-butadiene can be efficiently recovered from heavy C4 byproducts of a 1, 3-butadiene extraction device, and the content of the 1, 2-butadiene can reach 97%.

Description

Technical Field

[0001] The invention relates to the technical field of continuous extraction distillation recovery, and in particular to a continuous distillation recovery process and system for 1,2-butadiene. Background Art

[0002] In the continuous polymerization production process of solution styrene butadiene rubber and low-cis polybutadiene rubber, a gel inhibitor that can produce chain transfer must be added, that is, high-purity 1,2-butadiene. Otherwise, the active polymer molecular chains are prone to form gels during the production process, and these gels will be deposited on the stirring paddles, the inner wall of the reactor, and the dead corners of the pipeline. These deposited gels still have polymerization activity and will continue to react with the monomers to form macromolecular micelles, which will eventually lead to equipment blockage, production obstruction, and a significant increase in the gel content and quality of rubber products. By adjusting the reaction kinetics, 1,2-butadiene can effectively inhibit the formation of gels without affecting the polymerization and product quality.

[0003] 1,2-Butadiene is a volatile colorless liquid with a special smell, a boiling point of 10.9°C, a molecular weight of 54.09g / mol, and is insoluble in water but soluble in benzene and other polar organic solvents. According to existing patent literature, there are relatively few reports on new technologies and new process routes for 1,2-butadiene. For example, the US3751511 patent uses 2-butyne as a raw material to isomerize 1,2-butadiene through a catalyst composed of a first main group metal element and a fatty alcohol. The 1984 Japanese patent (Tokkai Sho 59-190929) uses an alkali metal hydroxide suspended or dissolved in a cationic solvent to prepare a catalyst to achieve the same purpose. In addition, in 1982, the Japanese Chemical Association reported that calcium oxide was used as a catalyst to isomerize various alkynes at a high temperature of 600°C to prepare 1,2-butadiene. However, these methods require specific compounds as raw materials, use different catalysts, and obtain 1,2-butadiene through complex chemical reaction steps under relatively harsh temperature and pressure conditions, which places high demands on raw material selection and processing. At the same time, these processes also involve safety and environmental regulations, and most of them use intermittent production processes, which cannot effectively guarantee production capacity and quality.

[0004] In the process of petroleum cracking ethylene, a large amount of C4 fraction by-products are produced, including 1,3-butadiene, isobutylene, 1-butene, cis-2-butene, trans-2-butene, 1,2-butadiene and C5 hydrocarbons. 1,2-Butadiene is usually present in the heavy C4 by-product of the 1,3-butadiene extraction unit using C4 fraction as raw material, and the content is usually between 4% and 15%. Heavy C4 is usually sold as fuel, while the 1,2-butadiene therein has a high recycling value. The CN101337858 patent uses the heavy C4 component of the 1,3-butadiene extraction unit as raw material, requires the content of 1,2-butadiene to be ≥7%, adopts chemical separation technology, and uses ordinary distillation technology after water washing to achieve heavy and light removal on the same tower, and continuously extracts the removed 1,2-butadiene from the side line. Although the process is simple, requires little investment and is easy to operate, the product purity of 1,2-butadiene is only 40%, which is far from meeting the production requirements of SSBR and LCBR. Patent CN103242126 also uses heavy carbon four byproducts as raw materials. It first removes light components such as 1,3-butadiene through a light removal tower, and then sends the tower bottom material to a heavy removal tower to remove heavy components such as C5, and obtains high-purity 1,2-butadiene from the top of the tower. This process effectively improves the purity of the product to more than 97%, but it also faces problems such as high energy consumption, high raw material requirements, large equipment investment, and low raw material utilization. A lot of 1,2-butadiene has not been effectively recovered.

[0005] At present, China has not yet produced high-purity 1,2-butadiene, and is completely dependent on imports, facing high risks, and the stability of the supply needs to be improved urgently. In addition, the introduction of foreign technology is not only expensive, but also has technical limitations. Therefore, it is urgent to develop a simple, practical, economical and efficient 1,2-butadiene production process. Summary of the invention

[0006] The present invention aims to solve the above problems, and therefore provides a simple, feasible, economical and efficient continuous extraction distillation process, which can efficiently recover high-purity 1,2-butadiene from the heavy carbon four by-products of the 1,3-butadiene extraction unit, and the content of 1,2-butadiene can be as high as 97%.

[0007] The present invention provides a continuous distillation recovery process for 1,2-butadiene, comprising the following steps: S10: The heavy C4 raw material and the extractant are preheated and enter the extractive distillation tower for distillation. The light component A is evaporated from the top of the tower and condensed, and enters the light component reflux tank and returns to the top of the tower as reflux; the heavy component A is discharged from the bottom of the tower and enters the extractant separation tower; S20: The heavy component A enters the extractant separation tower for distillation, and the light component B is evaporated from the top of the tower and condensed and enters the separation reflux tank. A part of the light component B in the separation reflux tank returns to the top of the tower as reflux, and the other part enters the deweighting tower; the heavy component B is discharged from the bottom of the tower and enters the extractant kettle liquid tank, and then enters the extractive distillation tower after passing through the heat exchanger; S30: The light component B enters the de-heavy tower to remove the heavy component. The light component C is evaporated from the top of the tower and condensed, and then enters the 1,2-butadiene reflux tank for buffering, and then enters the 1,2-butadiene storage tank; the heavy component C is discharged from the bottom of the tower and enters the heavy component kettle liquid tank, and then enters the waste liquid tank; Among them, the heavy C4 raw material and the extractant are preheated by a heat exchanger, and the heat exchanger uses the heavy component B as a heat source.

[0008] Further, in step S10, the heavy carbon four raw material and the extractant are preheated and enter the extractive distillation tower for distillation, which specifically includes: The extractant in the extractant recovery tank and the heavy carbon four raw material enter the static mixer to obtain a mixture, and then pass through a heat exchanger to heat the mixture to the feed temperature, and then the mixture is sent to the middle part of the extractive distillation tower; Wherein, the extractant includes acetonitrile, and the feed ratio of acetonitrile to heavy carbon four raw material is (0.05-2.0):1.

[0009] Furthermore, in step S20, the heavy component B in the extractant kettle liquid tank passes through the heat exchanger and then continues to enter the top of the extractive distillation tower.

[0010] Further, the operating parameters of the extractive distillation column include: The bottom temperature of the extractive distillation tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-70°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0011] Further, the operating parameters of the extractant separation tower include: The bottom temperature of the extractant separation tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-60°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0012] Further, the operating parameters of the deweighting tower include: The bottom temperature of the deweighting tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-60°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0013] The present invention also provides a 1,2-butadiene continuous distillation and recovery system, which adopts the 1,2-butadiene continuous distillation and recovery process as described above; the 1,2-butadiene continuous distillation and recovery system comprises an extractive distillation unit, an extractant separation and recovery unit and a weight removal unit which are connected in sequence, the extractive distillation unit comprises an extractive distillation tower, a heat exchanger and a light component reflux tank, the extractant separation and recovery unit comprises an extractant separation tower, a separation reflux tank and an extractant kettle liquid tank, and the weight removal unit comprises a weight removal tower, a 1,2-butadiene reflux tank and a heavy component kettle liquid tank; The middle feed port of the extractive distillation tower is connected to the first branch of the heat exchanger, the top feed port is connected to the second branch of the heat exchanger, and the top discharge port flows back to the top of the extractive distillation tower after passing through the light component reflux tank; The middle feed port of the extractant separation tower is connected with the bottom discharge port of the extractive distillation tower, the top discharge port is refluxed to the extractant separation tower after passing through the separation reflux tank, and the bottom discharge port is connected with the extractant kettle liquid tank; the outlet of the extractant kettle liquid tank is connected with the inlet of the heat exchanger; The middle feed inlet of the de-weighting tower is connected with the separation reflux tank of the extractant separation tower, and the top discharge port refluxes to the de-weighting tower after passing through the 1,2-butadiene reflux tank.

[0014] Furthermore, the 1,2-butadiene continuous distillation recovery system also includes a heavy carbon four raw material storage tank and an extractant recovery tank; the extraction distillation unit also includes a static mixer, The inlet of the static mixer is communicated with the heavy C4 raw material storage tank and the extractant recovery tank, and the outlet of the static mixer is communicated with the heat exchanger.

[0015] Furthermore, the 1,2-butadiene continuous distillation recovery system also includes a 1,2-butadiene storage tank and a waste liquid tank; The inlet of the 1,2-butadiene storage tank is connected to the outlet of the 1,2-butadiene reflux tank; one inlet of the waste liquid tank is connected to the outlet of the light component reflux tank of the extraction distillation tower, and the other inlet of the waste liquid tank is connected to the outlet of the heavy component kettle liquid tank of the deweighting tower.

[0016] Furthermore, the extractive distillation unit also includes a 1# reboiler arranged at the bottom of the extractive distillation tower, the extractant separation and recovery unit also includes a 2# reboiler arranged at the bottom of the extractant separation tower, and the deweighting unit also includes a 3# reboiler arranged in the deweighting tower.

[0017] After adopting the technical solution of the present invention, the following technical effects can be achieved: (1) The heavy carbon four byproduct is used as a raw material, which is widely available and inexpensive, avoiding the sale of 1,2-butadiene as fuel, thereby reducing carbon emissions; the production process of the present invention can obtain 1,2-butadiene that does not contain water and harmful impurities, has high purity, and fully meets the production requirements of solution-polymerized styrene-butadiene rubber; the production device of the present invention has low equipment investment, simple process flow, mild conditions and convenient operation; (2) Acetonitrile is used as the extractant to extract 1,2-butadiene from the heavy carbon four components with high selectivity and efficiency. The boiling point of acetonitrile is 82°C, while the boiling point of 1,2-butadiene is only 11°C. The difference between the two is significant and they are easy to separate. At the same time, the feed ratio of acetonitrile to raw material is not high, which significantly improves the recovery rate of 1,2-butadiene and ensures low energy consumption. (3) During the production process, the high-temperature extractant at the bottom of the extractant separation tower and the preheated raw materials from the heat exchanger are used to save steam and refrigerant, ensuring low energy consumption for the overall operation; (4) The extractant enters from the top of the extractive distillation tower and is fully mixed with the rising air flow in the tower to carry out mass transfer and heat transfer. It then enters the process of separation, recovery and recycling, which improves the extraction effect of 1,2-butadiene without causing pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 This is a continuous extraction distillation recovery process flow chart provided for this embodiment.

[0019] Description of reference numerals: 10-extractive distillation unit; 11-extractive distillation tower; 12-heat exchanger; 13-light component reflux tank; 14-static mixer; 15-1# reboiler; 16-kettle liquid extraction pump; 17-light component condenser; 18-light component reflux / extraction pump; 20-extractant separation and recovery unit; 21-extractant separation tower; 22-separation reflux tank; 23-extractant kettle liquid tank; 24-2# reboiler; 25-extractant extraction pump; 26-separation condenser; 27-separation Reflux pump; 28-separation and production pump; 30-de-weighting unit; 31-de-weighting tower; 32-1,2-butadiene reflux tank; 33-heavy component kettle liquid tank; 34-3# reboiler; 35-heavy component production pump; 36-1,2-butadiene condenser; 37-1,2-butadiene reflux / production pump; 40-heavy C4 raw material storage tank; 41-raw material feed pump; 50-extractant recovery tank; 51-extractant feed pump; 60-1,2-butadiene storage tank; 70-waste liquid tank. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] There are many patents on the preparation technology of 1,2-butadiene abroad. For example, U.S. Patent US3751511 uses 2-butyne as a raw material, and uses a catalyst composed of a first main group metal element and a fatty alcohol to carry out an isomerization reaction to successfully produce 1,2-butadiene. In addition, a patent published in Japan in 1984 (Tokkai Sho 59-190929) proposed suspending or dissolving an alkali metal hydroxide in a cationic solvent, or loading it on a carrier such as activated carbon or magnesium oxide, for the isomerization of 2-butyne to prepare 1,2-butadiene. In 1982, the Chemical Society of Japan also reported that calcium oxide was used as a catalyst to isomerize a variety of alkynes at a high temperature of 600°C to produce 1,2-butadiene. However, these methods all rely on specific compounds as raw materials, require the use of different catalysts, and obtain 1,2-butadiene through complex chemical reactions (such as isomerization, reduction, decomposition, etc.) under harsh temperature and pressure conditions. In addition, there are high requirements for the selection, pretreatment and post-treatment of raw materials, and some reaction processes and production aids are also subject to safety and environmental regulations. At the same time, the existing processes are mostly intermittent production, which makes it difficult to effectively guarantee production capacity and product quality.

[0022] Domestically, patent CN101337858 uses the heavy carbon four components of the 1,3-butadiene extraction device as raw materials. After water washing, the ordinary distillation process is used to achieve the process of removing heavy and light components on the same tower, and finally 1,2-butadiene is continuously extracted from the side line. This process has the advantages of simple process, low investment and convenient operation, but the product purity is only 40%, which is far from meeting the production requirements of SSBR and LCBR. Another patent CN103242126 also uses heavy carbon four by-products as raw materials. First, the light components (such as 1,3-butadiene, cis-2-butene, trans-2-butene, 1-butyne) are removed through the light tower, and then the tower bottom material is sent to the heavy tower to remove heavy components such as C5, so as to obtain high-purity 1,2-butadiene. This process effectively improves the product purity to more than 97%, but it also faces problems such as high energy consumption, large equipment investment, high raw material requirements and low recovery rate of 1,2-butadiene.

[0023] An embodiment of the present invention provides a continuous distillation recovery process for 1,2-butadiene, comprising the following steps: S10: The heavy C4 raw material and the extractant are preheated and enter the extractive distillation tower for distillation. The light component A is evaporated from the top of the tower and condensed, and enters the light component reflux tank and returns to the top of the tower as reflux; the heavy component A is discharged from the bottom of the tower and enters the extractant separation tower; S20: The heavy component A enters the extractant separation tower for distillation, and the light component B is evaporated from the top of the tower and condensed and enters the separation reflux tank. A part of the light component B in the separation reflux tank returns to the top of the tower as reflux, and the other part enters the deweighting tower; the heavy component B is discharged from the bottom of the tower and enters the extractant kettle liquid tank, and then enters the extractive distillation tower after passing through the heat exchanger; S30: The light component B enters the de-heavy tower to remove the heavy component. The light component C is evaporated from the top of the tower and condensed, and then enters the 1,2-butadiene reflux tank for buffering, and then enters the 1,2-butadiene storage tank; the heavy component C is discharged from the bottom of the tower and enters the heavy component kettle liquid tank, and then enters the waste liquid tank; Among them, the heavy C4 raw material and the extractant are preheated by a heat exchanger, and the heat exchanger uses the heavy component B as a heat source.

[0024] The present invention relates to a continuous distillation recovery process for 1,2-butadiene. The process realizes efficient separation and recovery of 1,2-butadiene through continuous distillation and extraction processes, thereby maximizing resource utilization. The heat exchanger and reflux tank design adopted reduce energy consumption, reduce dependence on external energy, and also reduce waste liquid generation, thereby contributing to environmental protection. Through a fine separation process, the purity of the final product 1,2-butadiene can be effectively improved to meet the strict requirements of industrial applications. The continuity feature of the process ensures the stability and efficiency of the production process, and is suitable for large-scale industrial applications.

[0025] In the production process of ethylene by petroleum cracking, a large amount of C4 fractions are produced as by-products, which mainly include 1,3-butadiene, isobutylene, butene-1, cis / trans-2-butene, 1,2-butadiene and C5 hydrocarbons. After being processed by the 1,3-butadiene extraction device, 1,2-butadiene is enriched in the heavy C4 by-product, and its content is usually between 4% and 15%. The present invention uses the heavy C4 by-product as a raw material and adopts a continuous extraction, distillation and recovery process to produce high-purity 1,2-butadiene.

[0026] The finished product indicators of 1,2-butadiene obtained by the continuous extraction distillation recovery process of the present invention are as follows: 1,2-butadiene content ≥97%; inhibitor (TBC) content ≤100ppm; C5 hydrocarbon content ≤0.6%; 1,3-butadiene content ≤0.3%; butene-1 and cis / trans-2-butene content ≤2.5%; C4-acetylene component content ≤300ppm.

[0027] It should be noted that all the heavy components B in the extractant kettle liquid tank are returned to the top of the extractive distillation tower.

[0028] In some embodiments of the present application, in step S10, the heavy carbon four raw material and the extractant are preheated and enter the extractive distillation tower for distillation, which specifically includes: The extractant in the extractant recovery tank and the heavy carbon four raw material enter the static mixer to obtain a mixture, and then pass through a heat exchanger to heat the mixture to the feed temperature, and then the mixture is sent to the middle part of the extractive distillation tower; Wherein, the extractant includes acetonitrile, and the feed ratio of acetonitrile to heavy carbon four raw material is (0.05-2.0):1.

[0029] The heavy C4 raw material is mixed with acetonitrile in a static mixer to form a uniform mixture, which is then heated to the required feed temperature through a heat exchanger. The heated mixture is fed into the middle of the extractive distillation tower for subsequent distillation separation. By selecting acetonitrile as the extractant, the separation of the heavy C4 raw material can be effectively promoted due to its good solubility and selectivity. The feed ratio of the extractant to the heavy C4 raw material is in the range of (0.05-2.0):1, ensuring effective extraction at different concentrations.

[0030] By preheating and mixing, the extraction process is optimized, which can significantly improve the separation efficiency of heavy C4 raw materials. By using heavy component B as the heat source and preheating with a heat exchanger, it helps to reduce overall energy consumption and improve economic efficiency. The adjustability of the feed ratio allows the method to adapt to different production needs and raw material characteristics, improving the flexibility of the process.

[0031] In some embodiments of the present application, in step S20, the heavy component B in the extractant kettle liquid tank passes through the heat exchanger and then continues to enter the top of the extractive distillation tower.

[0032] In step S20, after the heavy component B in the extractant kettle liquid tank is cooled by the low-temperature heavy carbon four raw material mixed flow, it is continued to be sent to the top of the extractive distillation tower. The heavy component B separated in the previous step is an important component in the distillation process and needs to be further processed to improve the purity of the product. The heavy component B passes through the heat exchanger, the purpose of which is to recover heat, and then preheat the raw material to adapt to the separation conditions in the subsequent distillation tower. Furthermore, the heavy component B that has recovered heat and cooled down is sent to the top of the extractive distillation tower to ensure that it can fully contact with the rising steam and optimize the separation effect.

[0033] By recovering the heat of the heavy component B, the energy utilization rate can be improved, the overall energy consumption can be reduced, and the economic efficiency of the process can be improved. Sending the treated heavy component B to the top of the tower can help maintain the stable operating conditions in the distillation tower and improve the purity and quality of the product.

[0034] In some embodiments of the present application, the operating parameters of the extractive distillation column include: The bottom temperature of the extractive distillation tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-70°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0035] The temperature and pressure of the tower bottom affect the evaporation and separation efficiency of the liquid. Appropriate temperature and pressure help improve the efficiency of the extraction process. Controlling the temperature and pressure at the top of the tower can ensure the effective separation of light components and optimize the contact conditions between steam and liquid. The height of the packing section directly affects the gas-liquid contact area in the tower. The appropriate height can improve the separation efficiency and ensure better material transfer. Adjusting the reflux ratio can optimize the distribution of materials in the tower to meet different separation requirements, thereby improving the purity of the target product.

[0036] In some embodiments of the present application, the operating parameters of the extractant separation tower include: The bottom temperature of the extractant separation tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-60°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0037] Set appropriate tower bottom temperature and pressure range to ensure the efficiency and stability of the extractant separation process, while avoiding improper operation or equipment damage caused by too high or too low temperature. By controlling the temperature and pressure at the top of the tower, the steam separation effect is optimized to ensure that the light components can effectively escape from the top of the tower. The height of the packing section affects the separation efficiency of the tower. The appropriate height can increase the gas-liquid contact area and improve the separation effect. The adjustment of the reflux ratio can optimize the material transfer in the tower, adapt to the separation requirements of different raw materials and target products, and enhance the purity of the product.

[0038] In some embodiments of the present application, the operating parameters of the deweighting tower include: The bottom temperature of the deweighting tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-60°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0039] Setting the appropriate tower bottom temperature and pressure is the key to ensure the effective separation of 1,2-butadiene. These conditions affect the evaporation rate and separation efficiency of the liquid. Controlling the temperature and pressure at the top of the tower helps to ensure that light components (such as 1,2-butadiene) escape smoothly from the top of the tower, improving the overall separation effect. The height of the packing section affects the effectiveness of gas-liquid contact, and the appropriate height can increase the accuracy and efficiency of separation. Adjusting the reflux ratio can optimize the distribution of materials in the tower, adapt to different separation requirements, and improve the purity and yield of the product.

[0040] Reasonable operating parameters can significantly improve the separation efficiency of 1,2-butadiene and ensure the high purity of the product. The wide range of parameters enables the deweighting tower to adapt to different raw materials and production conditions, enhancing the flexibility of the process. Reasonable control of the temperature and pressure in the tower helps to reduce operating fluctuations, ensure the stability of the separation process, and reduce the risk of equipment failure. By optimizing the reflux ratio and energy use, the overall economy is improved, the production cost is reduced, and the feasibility of industrial application is enhanced.

[0041] The embodiment of the present invention further provides a 1,2-butadiene continuous distillation and recovery system, which adopts the 1,2-butadiene continuous distillation and recovery process as described above; the 1,2-butadiene continuous distillation and recovery system comprises an extractive distillation unit 10, an extractant separation and recovery unit 20 and a de-weighting unit 30 which are sequentially connected, the extractive distillation unit 10 comprises an extractive distillation tower 11, a heat exchanger 12, and a light component reflux tank 13, the extractant separation and recovery unit 20 comprises an extractant separation tower 21, a separation reflux tank 22, and an extractant kettle liquid tank 23, and the de-weighting unit 30 comprises a de-weighting tower 31, a 1,2-butadiene reflux tank 32, and a heavy component kettle liquid tank 33; The middle feed port of the extractive distillation tower 11 is connected to the first branch of the heat exchanger 12, the top feed port is connected to the second branch of the heat exchanger 12, and the top discharge port is refluxed to the top of the extractive distillation tower 11 after passing through the light component reflux tank 13; The middle feed port of the extractant separation tower 21 is connected to the bottom discharge port of the extractive distillation tower 11, the top discharge port is refluxed to the extractant separation tower 21 after passing through the separation reflux tank 22, and the bottom discharge port is connected to the extractant kettle liquid tank 23; the outlet of the extractant kettle liquid tank 23 is connected to the inlet of the heat exchanger 12; The middle feed port of the deweighting tower 31 is connected to the separation reflux tank 22 of the extractant separation tower 21 , and the top discharge port refluxes to the deweighting tower 31 after passing through the 1,2-butadiene reflux tank 32 .

[0042] The embodiment of the present invention provides a 1,2-butadiene continuous distillation recovery system, which adopts the above-mentioned 1,2-butadiene continuous distillation recovery process, and its structure includes three units connected in sequence: an extractive distillation unit 10, an extractant separation and recovery unit 20, and a de-weighting unit 30. The extractive distillation unit 10, the extractant separation and recovery unit 20, and the de-weighting unit 30 are connected in sequence. Figure 1 Not shown.

[0043] The system design optimizes the extraction and separation efficiency of 1,2-butadiene by effectively connecting each unit to form a continuous distillation recovery process. Specifically: the setting of the extraction distillation unit 10 ensures efficient component separation, and uses the heat exchanger 12 to achieve energy recovery and reduce energy consumption; the extractant separation and recovery unit 20 can effectively recover and separate the extractant, reduce the waste of raw materials, and enhance economic efficiency; the de-heavy unit 30 combines the separation and recovery of heavy components to ensure the purity of the final product and optimize the entire production process.

[0044] The design of the 1,2-butadiene continuous distillation recovery system improves the separation and recovery efficiency of 1,2-butadiene, ensuring product quality and yield. Through the application of the heat exchanger 12, the recovery of heat energy is achieved, the energy consumption is reduced, and the requirements of sustainable development are met. The recovery of the extractant and the effective separation of the heavy components reduce the consumption of raw materials and improve the overall production economic benefits.

[0045] In some embodiments of the present application, the 1,2-butadiene continuous distillation recovery system further includes a heavy carbon four raw material storage tank 40 and an extractant recovery tank 50; the extraction distillation unit 10 further includes a static mixer 14, The inlet of the static mixer 14 is communicated with the heavy C4 raw material storage tank 40 and the extractant recovery tank 50 , and the outlet of the static mixer 14 is communicated with the heat exchanger 12 .

[0046] The heavy carbon four raw material storage tank 40 is used to store the heavy carbon four raw material, providing a stable raw material supply for the extraction and distillation process, ensuring the continuity and stability of production. The extractant recovery tank 50 is used to recover and store the used extractant, reducing resource waste and improving economic benefits. The static mixer 14 fully mixes the heavy carbon four raw material and the extractant to ensure that the composition of the mixture is uniform before entering the heat exchanger 12, thereby optimizing the subsequent separation process.

[0047] In some embodiments of the present application, the 1,2-butadiene continuous distillation recovery system further includes a 1,2-butadiene storage tank 60 and a waste liquid tank 70; The inlet of the 1,2-butadiene storage tank 60 is connected to the outlet of the 1,2-butadiene reflux tank 32; one inlet of the waste liquid tank 70 is connected to the outlet of the light component reflux tank 13, and the other inlet of the waste liquid tank 70 is connected to the outlet of the heavy component kettle liquid tank 33.

[0048] The 1,2-butadiene storage tank 60 is responsible for storing the finished 1,2-butadiene obtained after distillation, ensuring a stable supply of the finished product during the production process and facilitating subsequent processing. The waste liquid tank 70 is used to collect and store the waste liquid generated during the distillation process, including non-target products separated from light components and heavy components, which helps to achieve systematization of waste management and processing. The introduction of the finished product storage tank and the waste liquid tank 70 enhances the continuity of the production process, allowing the system to operate efficiently and reduce downtime.

[0049] In some embodiments of the present application, the extraction distillation unit 10 also includes a 1# reboiler 15 disposed at the bottom of the extraction distillation tower 11, the extractant separation and recovery unit 20 also includes a 2# reboiler 24 disposed at the bottom of the extractant separation tower 21, and the deweighting unit 30 also includes a 3# reboiler 34 disposed at the deweighting tower 31.

[0050] The 1# reboiler 15 is arranged at the bottom of the extractive distillation tower 11. By transferring heat to the bottom of the extractive distillation tower 11, the gas-liquid contact in the tower is promoted, the separation efficiency is improved, and the high-purity 1,2-butadiene product is ensured. The 2# reboiler 24 is arranged at the bottom of the extractant separation tower 21, and is used to heat and regenerate the extractant to enhance the separation performance of the extractant. The 3# reboiler 34 is arranged at the de-weighting tower 31 of the de-weighting unit 30, and is responsible for providing appropriate heat to promote the separation of the heavy components.

[0051] By setting up multiple reboilers, the interaction between the liquid phase and the gas phase is enhanced, the efficiency of extraction and separation is improved, and the high purity of the product is ensured. The effective use of the reboiler allows the heat to be recycled, reducing the demand for external heat sources, thereby reducing energy consumption and improving the economy of the system. The introduction of 2# reboiler 24 optimizes the recovery process of the extractant, reduces the cost of raw materials, and complies with the principles of green chemistry. By precisely controlling the operation of the reboiler, the stable operation of the extraction and separation process is ensured, the operation fluctuations are reduced, and the overall production efficiency is improved.

[0052] After adopting the technical solution of the present invention, the following technical effects can be achieved: 1. Raw material advantage: Using heavy carbon four by-products as raw materials, which are widely available and inexpensive, avoids selling 1,2-butadiene as fuel, thereby reducing carbon emissions.

[0053] 2. High-purity products: The production process of the present invention can obtain 1,2-butadiene that does not contain moisture and harmful impurities and has high purity, which can fully meet the production requirements of solution-polymerized styrene-butadiene rubber.

[0054] 3. Continuous production: It adopts continuous production technology with large production capacity to meet its own usage needs.

[0055] 4. Small equipment investment: The production device of the present invention has small equipment investment, simple process flow, mild conditions and easy operation.

[0056] 5. Efficient extraction: Using acetonitrile as the extractant, 1,2-butadiene can be extracted from the heavy carbon four components with high selectivity and efficiency. The boiling point of acetonitrile is 82°C, while the boiling point of 1,2-butadiene is only 11°C. The difference between the two is significant and easy to separate. At the same time, the feed ratio of acetonitrile to raw materials is not high, which significantly improves the recovery rate of 1,2-butadiene and ensures low energy consumption.

[0057] 6. Flexible adjustment: The feed ratio of acetonitrile extractant to heavy carbon four raw material can be adjusted in real time within a wide range to ensure excellent extraction effect, and the requirements for the stability of 1,2-butadiene content and specifications in the raw material are not high.

[0058] 7. Energy-saving operation: During the production process, the high-temperature extractant at the bottom of the extractant separation tower and the preheated raw materials from the heat exchanger are used to save steam and refrigerant, ensuring low energy consumption for the overall operation.

[0059] 8. Efficient mixing: The extractant enters from the top of the extraction distillation tower, fully mixes with the rising air flow in the tower for mass transfer and heat transfer, and then enters the separation, recovery and recycling process, which improves the extraction effect of 1,2-butadiene without causing pollution.

[0060] 9. Environmental protection and no waste: No three wastes are discharged during the entire production process, keeping the environment pollution-free.

[0061] 10. Technological independence: This invention breaks the foreign technology monopoly, avoids dependence on imported technology, saves high technology transfer costs, and ensures the stability of supply.

[0062] Example 1 The embodiment of the present invention provides a 1,2-butadiene continuous distillation recovery system, which is as follows: The continuous extraction distillation recovery system designed in this embodiment mainly includes four parts: a tank area, an extraction distillation unit 10, an extractant separation and recovery unit 20 and a weight removal unit 30.

[0063] 1. Tank farm The tank area consists of the following parts: heavy carbon four raw material storage tank 40, raw material feed pump 41; extractant recovery tank 50, extractant feed pump 51; 1,2-butadiene storage tank 60; waste liquid tank 70. All tank materials are made of carbon steel.

[0064] The storage conditions are as follows: the storage temperature range of raw materials, extractants, products and waste liquid is -50℃ to 80℃, and the pressure is set to 0.1MPa (normal pressure). The heavy carbon four raw material storage tank 40, the extractant recovery tank 50 and the 1,2-butadiene storage tank 60 need to be protected by nitrogen, while the waste liquid tank 70 can use air atmosphere.

[0065] There are many kinds of extractants, including methanol, ethanol, propanol, isopropanol, n-butanol, etc., and acetonitrile is the best choice. When using acetonitrile as an extractant, the feed ratio of acetonitrile to heavy carbon four raw materials should be controlled between (0.05-2.0):1. Acetonitrile has the ability to extract 1,2-butadiene with high selectivity and high efficiency, and its boiling point of 82°C is significantly different from the boiling point of 1,2-butadiene of 11°C, which is easy to separate. In addition, the feed ratio can be adjusted according to the different levels of raw materials to ensure excellent extraction effect, thereby improving the recovery rate of 1,2-butadiene, while reducing energy consumption and reducing the requirements for raw material level.

[0066] 2. Extraction distillation unit 10 The extractive distillation unit 10 is composed of the following equipment: a heat exchanger 12, an extractive distillation tower 11, a No. 1 reboiler 15, a kettle liquid extraction pump 16, a light component condenser 17, a light component reflux tank 13, and a light component reflux / extraction pump 18. The equipment in the unit is made of carbon steel.

[0067] The equipment process conditions are as follows: The raw material inlet temperature of the heat exchanger 12 is room temperature, and the outlet temperature (i.e., the feed temperature of the extractive distillation tower 11) is 0°C-80°C. The heating medium comes from the extractant kettle liquid tank 23 at the bottom of the extractant separation tower 21, and the temperature before heat exchange is 50°C-90°C, and the temperature after heat exchange is 35°C-80°C.

[0068] The bottom temperature of the extractive distillation tower 11 is 35°C-100°C, the top temperature is room temperature-70°C, the bottom pressure is 0.2MPa-0.6MPa, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0069] The 1# reboiler 15 uses low-pressure steam as a heat medium, and the light component condenser 17 uses low-temperature circulating water as a refrigerant.

[0070] 3. Extraction agent separation and recovery unit 20 The extractant separation and recovery unit 20 comprises: an extractant separation tower 21, a No. 2 reboiler 24, an extractant kettle liquid tank 23, an extractant extraction pump 25, a separation condenser 26, a separation reflux tank 22, a separation reflux pump 27, and a separation extraction pump 28. The equipment of the unit is made of carbon steel.

[0071] The equipment process conditions are as follows: The temperature of the extractant kettle liquid in the extractant kettle liquid tank 23 is 50°C-90°C.

[0072] The bottom temperature of the extractant separation tower 21 is 35°C-100°C, the top temperature is room temperature-60°C, the bottom pressure is 0.2MPa-0.6MPa, the top pressure is 0.19-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0073] The 2# reboiler 24 uses low-pressure steam as a heat medium, and the separation condenser 26 uses low-temperature circulating water as a refrigerant.

[0074] 4. Weight removal unit 30 The de-weighting unit 30 includes: a de-weighting tower 31, a 3# reboiler 34, a heavy component kettle liquid tank 33, a heavy component extraction pump 35, a 1,2-butadiene condenser 36, a 1,2-butadiene reflux tank 32, and a 1,2-butadiene reflux / extraction pump 37. The equipment of the unit is made of carbon steel.

[0075] The equipment process conditions are as follows: The bottom temperature of the deweighting tower 31 is 35°C-100°C, the top temperature is room temperature-60°C, the bottom pressure is 0.2MPa-0.6MPa, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

[0076] The 3# reboiler 34 uses low-pressure steam as a heat medium, and the 1,2-butadiene condenser 36 uses low-temperature circulating water as a refrigerant.

[0077] Example 2 The embodiment of the present invention provides a 1,2-butadiene continuous distillation recovery process, which is as follows: In the continuous extraction and distillation recovery process of this embodiment, the heavy C4 raw material in the heavy C4 raw material storage tank is continuously fed into the static mixer through the raw material feed pump. At the same time, the extractant is also continuously fed into the same static mixer through the extractant feed pump, fully mixed with the heavy C4 raw material, and the feed ratio is adjusted in real time, and then fed into the middle of the extraction distillation tower together.

[0078] Before the raw materials enter the extractive distillation tower, they are first preheated by a heat exchanger. The preheating liquid comes from the high-temperature extractant recovery liquid in the extractant kettle tank, so that the raw materials reach a suitable feeding temperature. At the same time, the cooled high-temperature extractant is continuously input from the top of the extractive distillation tower and fully mixed with the rising airflow in the tower to complete mass transfer and heat transfer. This preheating process effectively reduces energy consumption.

[0079] In the extractive distillation tower, light component impurities are removed from the top of the tower, and the 1,2-butadiene extract is continuously input into the extractant separation tower through the kettle liquid extraction pump for separation and recovery of the extractant. The extractant recovery liquid is continuously extracted from the extractant kettle liquid tank at the bottom of the extractant separation tower through the extractant extraction pump, and finally returned to the extractive distillation tower for repeated use.

[0080] 1,2-butadiene containing heavy components is continuously extracted from the top of the extractive distillation tower and fed into the de-heavy tower through a separation extraction pump to further remove the heavy components. After entering the de-heavy tower, the heavy components are removed from the bottom of the tower, and the residual liquid enters the heavy component kettle liquid tank, which is then sent to the waste liquid tank through the heavy component extraction pump for loading and recycling. At the same time, the light component impurities from the light component reflux tank of the extractive distillation tower will also enter the waste liquid tank.

[0081] Finally, the high-purity 1,2-butadiene gas with a content of up to 97% is discharged from the top of the deweighting tower, flows into the 1,2-butadiene reflux tank through the 1,2-butadiene condenser for buffering, and then is produced by the reflux pump 1,2-butadiene reflux / production pump and transported to the 1,2-butadiene storage tank, ready to enter the polymerization unit for the production of SSBR.

[0082] Figure 1 This is a continuous extraction distillation recovery process flow chart provided for this embodiment.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A continuous distillation recovery process for 1,2-butadiene, characterized in that: The following steps are involved: S10: The heavy C4 raw material and the extractant are preheated and enter the extractive distillation tower for distillation. The light component A is evaporated from the top of the tower and condensed, and enters the light component reflux tank and returns to the top of the tower as reflux; the heavy component A is discharged from the bottom of the tower and enters the extractant separation tower; S20: The heavy component A enters the extractant separation tower for distillation, and the light component B is evaporated from the top of the tower and condensed and enters the separation reflux tank. A part of the light component B in the separation reflux tank returns to the top of the tower as reflux, and the other part enters the deweighting tower; the heavy component B is discharged from the bottom of the tower and enters the extractant kettle liquid tank, and then enters the extractive distillation tower after passing through the heat exchanger; S30: The light component B enters the de-heavy tower to remove the heavy component. The light component C is evaporated from the top of the tower and condensed, and then enters the 1,2-butadiene reflux tank for buffering, and then enters the 1,2-butadiene storage tank; the heavy component C is discharged from the bottom of the tower and enters the heavy component kettle liquid tank, and then enters the waste liquid tank; Among them, the heavy C4 raw material and the extractant are preheated by a heat exchanger, and the heat exchanger uses the heavy component B as a heat source.

2. The 1,2-butadiene continuous distillation recovery process according to claim 1, characterized in that: In step S10, the heavy carbon four raw material and the extractant are preheated and enter the extractive distillation tower for distillation, which specifically includes: The extractant in the extractant recovery tank and the heavy carbon four raw material enter the static mixer to obtain a mixture, and then pass through a heat exchanger to heat the mixture to the feed temperature, and then the mixture is sent to the middle part of the extractive distillation tower; Wherein, the extractant includes acetonitrile, and the feed ratio of acetonitrile to heavy carbon four raw material is (0.05-2.0):

1.

3. The continuous distillation recovery process for 1,2-butadiene according to claim 1, characterized in that: In step S20, the heavy component B in the extractant kettle liquid tank passes through the heat exchanger and then continues to enter the top of the extractive distillation tower.

4. The continuous distillation recovery process for 1,2-butadiene according to claim 1, characterized in that: The operating parameters of the extractive distillation column include: The bottom temperature of the extractive distillation tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-70°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

5. The 1,2-butadiene continuous distillation recovery process according to claim 1, characterized in that: The operating parameters of the extractant separation column include: The bottom temperature of the extractant separation tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-60°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

6. The 1,2-butadiene continuous distillation recovery process according to claim 1, characterized in that: The operating parameters of the deweighting tower include: The bottom temperature of the deweighting tower is 35°C-100°C, the bottom pressure is 0.2MPa-0.6MPa, the top temperature is 20°C-60°C, the top pressure is 0.19MPa-0.59MPa, the packing section height is 10m-40m, and the reflux ratio is 0.5-10.

7. A 1,2-butadiene continuous distillation recovery system, characterized in that: The 1,2-butadiene continuous distillation recovery system adopts the 1,2-butadiene continuous distillation recovery process according to any one of claims 1 to 6; the 1,2-butadiene continuous distillation recovery system comprises an extractive distillation unit (10), an extractant separation and recovery unit (20) and a weight removal unit (30) connected in sequence, the extractive distillation unit (10) comprising an extractive distillation tower (11), a heat exchanger (12), and a light component reflux tank (13), the extractant separation and recovery unit (20) comprising an extractant separation tower (21), a separation reflux tank (22), and an extractant kettle liquid tank (23), and the weight removal unit (30) comprising a weight removal tower (31), a 1,2-butadiene reflux tank (32), and a heavy component kettle liquid tank (33); The middle feed port of the extractive distillation tower (11) is connected to the first branch of the heat exchanger (12), the top feed port is connected to the second branch of the heat exchanger (12), and the top discharge port flows back to the top of the extractive distillation tower (11) after passing through the light component reflux tank (13); The middle feed port of the extractant separation tower (21) is connected to the bottom discharge port of the extractive distillation tower (11), the top discharge port flows back to the extractant separation tower (21) after passing through the separation reflux tank (22), and the bottom discharge port is connected to the extractant kettle liquid tank (23); the outlet of the extractant kettle liquid tank (23) is connected to the inlet of the heat exchanger (12); The middle feed inlet of the deweighting tower (31) is connected to the separation reflux tank of the extractant separation tower (21), and the top discharge port flows through the 1,2-butadiene reflux tank (32) and then refluxes to the deweighting tower (31).

8. The 1,2-butadiene continuous distillation recovery system according to claim 7, characterized in that: The 1,2-butadiene continuous distillation recovery system further comprises a heavy carbon four raw material storage tank (40) and an extractant recovery tank (50); the extractive distillation unit (10) further comprises a static mixer (14), The inlet of the static mixer (14) is in communication with the heavy carbon four raw material storage tank (40) and the extractant recovery tank (50), and the outlet of the static mixer (14) is in communication with the heat exchanger (12).

9. The 1,2-butadiene continuous distillation recovery system according to claim 7, characterized in that: The 1,2-butadiene continuous distillation recovery system further includes a 1,2-butadiene storage tank (60) and a waste liquid tank (70); The inlet of the 1,2-butadiene storage tank (60) is connected to the outlet of the 1,2-butadiene reflux tank (32); one inlet of the waste liquid tank (70) is connected to the outlet of the light component reflux tank (13), and the other inlet of the waste liquid tank (70) is connected to the outlet of the heavy component kettle liquid tank (33).

10. The 1,2-butadiene continuous distillation recovery system according to claim 9, characterized in that: The extractive distillation unit (10) further comprises a #1 reboiler (15) arranged at the bottom of the extractive distillation tower (11), the extractant separation and recovery unit (20) further comprises a #2 reboiler (24) arranged at the bottom of the extractant separation tower (21), and the de-weighting unit (30) further comprises a #3 reboiler (34) arranged at the de-weighting tower (31).

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