A butadiene oligomerization reaction solvent recovery process and system

Abstract

The invention discloses a solvent recovery process and system for butadiene oligomerization reaction. In the process, after the material to be purified from the butadiene oligomerization reaction is rectified by the first distillation tower, a first mixture is extracted from the tower top, and a second mixture is extracted from the tower bottom. After the second mixture is rectified by the second distillation tower, a third mixture is extracted from the tower top. The third compound is subjected to fractional condensation treatment to obtain a fourth mixture of gas phase and a fifth mixture of liquid phase. After the fourth mixture is rectified by the third distillation tower, a solvent is extracted from the tower top, and a seventh mixture is extracted from the tower bottom. A sixth mixture is extracted from the tower bottom of the second distillation tower. After the sixth mixture is rectified by the fourth distillation tower, CDT is extracted from the tower top, and heavy components are extracted from the tower bottom. The invention can effectively remove water and butadiene from the material after the butadiene oligomerization reaction, obtain COD and CDT products with a purity of not less than 99%, save energy consumption and equipment investment through thermal coupling treatment, and reduce the overall process operation cost.

Description

Technical Field

[0001] The invention relates to the technical field of chemical product synthesis, and in particular to a butadiene oligomerization reaction solvent recovery process and system. Background Art

[0002] In the present invention, butadiene is used as an abbreviation for 1,3-butadiene, CAS No. 106-99-0, COD is used as an abbreviation for 1,5-cyclooctadiene, CAS No. 111-78-4; CDT is used as an abbreviation for 1,5,9-cyclododecatriene, CAS No. 706-31-0; butadiene oligomerization reaction and oligomerization reaction refer to butadiene cyclodimerization and cyclotrimerization reactions.

[0003] Butadiene is one of the three major olefins in the petrochemical production process. Butadiene is cyclodimerized under the action of a catalyst to produce COD, which is an important intermediate in the preparation of suberic acid, octenedioic acid and tetrachlorocyclooctane; butadiene is cyclotrimerized under the action of a catalyst to produce CDT, which is an important intermediate in the preparation of nylon 12, nylon 612 and nylon 1012. Therefore, with the continuous increase in industrial demand, the research on butadiene oligomerization process and reaction material separation and purification process has broad application prospects.

[0004] The butadiene oligomerization process is carried out in a solvent system. After the reaction, the material is deactivated by a terminator and then enters a solvent recovery unit for purification. In industrial production, the purity of COD and CDT products affects the subsequent production efficiency. It is worth noting that the composition of the material to be purified after the butadiene oligomerization reaction is very complex, generally including unreacted butadiene, water, solvent, butadiene dimer (including tetravinylcyclohexene and COD), butadiene trimer (including CDT), heavy components (including butadiene tetramer) and other substances. It is difficult for ordinary separation processes to achieve the technical requirements of high purity, low energy consumption and excellent process. Summary of the invention

[0005] In view of the above problems, the present invention provides a butadiene oligomerization reaction solvent recovery process and system, which can effectively remove butadiene and water in the material, improve the recycling effect of the recovered solvent, and obtain high-purity COD and CDT products.

[0006] Specifically, on the one hand, a butadiene oligomerization reaction solvent recovery process of the present invention comprises steps S1-S5, wherein

[0007] Step S1: After the material to be purified from the butadiene oligomerization reaction is rectified by the first distillation tower, a first mixture is taken out from the top of the tower, and a second mixture is taken out from the bottom of the tower, and the second mixture enters step S2;

[0008] Step S2: After the second mixture is rectified by the second distillation tower, a third mixture is taken from the top of the tower, and the third compound is subjected to fractional condensation to obtain a fourth mixture in gas phase and a fifth mixture in liquid phase, and the fourth mixture enters step S3; a sixth mixture is taken from the bottom of the second distillation tower, and the sixth mixture is input into step S4;

[0009] Step S3: After the fourth mixture is distilled in the third distillation tower (3), the solvent is extracted from the top of the tower, and the seventh mixture is extracted from the bottom of the tower;

[0010] Step S4: After the sixth mixture is distilled in the fourth distillation tower, CDT is taken from the top of the tower, and heavy components are taken from the bottom of the tower.

[0011] In the above technical solution, the first mixture mainly includes water and unreacted butadiene, and the second mixture is obtained after the first mixture is removed from the purified material.

[0012] Optionally, the first mixture is condensed by a first condenser to obtain a non-condensable gas (the main component is butadiene) and a liquid phase; the non-condensable gas is discharged into a flare for treatment, and the liquid phase is input into a reflux tank for phase separation to obtain an oil phase and a water phase, wherein the oil phase is returned to the top of the first distillation tower as reflux, and the water phase is discharged to a sewage treatment unit.

[0013] In the butadiene oligomerization reaction, water can cause the catalyst to be deactivated, thereby preventing the reaction from being carried out efficiently. Step S1 of the present invention can effectively discharge water from the material to be purified, thereby further reducing the water content in the recovered solvent; in addition, the present invention has a high solvent recovery rate, thereby improving the overall production efficiency.

[0014] Optionally, the operating pressure of the first distillation tower is 100~200kPaA, the top temperature is 10~60°C, the bottom temperature is 100~200°C, and the mass reflux ratio is 1~20.

[0015] In the above technical solution, the second mixture entering the second distillation tower is vaporized under the heating of the tower bottom reboiler, and the third mixture is extracted from the top of the tower. The third mixture is fractionated and condensed by the second condenser to obtain a fourth mixture in gas phase and a fifth mixture in liquid phase. The fourth mixture mainly includes solvent and butadiene dimer, and the fifth mixture is returned to the top of the second distillation tower as reflux. In addition, the sixth mixture mainly includes CDT and heavy components.

[0016] Optionally, the operating pressure of the second distillation tower is 2~50kPaA, preferably 2~20kPaA; the top temperature is 10~100°C; the bottom temperature is 120~180°C; and the mass reflux ratio is 1~10, preferably 1~5.

[0017] In the above technical scheme, after the solvent extracted from the top of the third distillation tower is condensed, a part of it is returned to the top of the distillation tower as reflux, and a part of it is extracted from the solvent recovery system of the present invention as a circulating solvent. The seventh mixture mainly includes COD and tetravinylcyclohexene, and is sent to the tank area after extraction.

[0018] Optionally, the operating pressure of the third distillation tower is 2~50kPaA, preferably 2~18kPaA; the top temperature is 10~100°C; the bottom temperature is 60~120°C, preferably 60~100°C; and the mass reflux ratio is 1~10, preferably 1~5.

[0019] In the above technical solution, the sixth mixture entering the fourth distillation tower is vaporized under the heating of the tower bottom reboiler, and the CDT extracted from the tower top is condensed, part of which is returned to the top of the distillation tower as reflux, and part of which is extracted as CDT product and sent to the tank area. The heavy components extracted from the tower bottom of the fourth distillation tower include butadiene tetramer and other heavy components, which are discharged and sent to the tank area for subsequent treatment after extraction.

[0020] Optionally, the operating pressure of the fourth distillation tower is 1~20kPaA, preferably 1~10kPaA; the tower top temperature is 100~150°C; the tower bottom temperature is 150~180°C; and the mass reflux ratio is 0.2~5, preferably 0.2~2.

[0021] In the above technical scheme, step S5 is also included. Specifically, after the seventh mixture is input into the fifth distillation tower for distillation, the seventh mixture is heated and vaporized, and a gas phase is extracted from the top of the tower; after the gas phase is condensed by the condenser, a part of it is returned to the top of the fifth distillation tower as reflux, and a part of it is extracted as a by-product tetravinylcyclohexene and sent to the tank area. A high-purity COD product is extracted from the bottom of the fifth distillation tower and sent to the tank area.

[0022] Optionally, the operating pressure of the fifth distillation tower is 5~50kPaA, preferably 5~15kPaA; the tower top temperature is 20~60°C; the tower bottom temperature is 80~150°C; and the mass reflux ratio is 5~50, preferably 5~10.

[0023] The above technical solution also includes heat coupling treatment. Specifically, the CDT extracted from the top of the fourth distillation tower is used as a heat source for vaporizing the bottom of the third distillation tower.

[0024] In large-scale industrial production, in addition to ensuring product purity, reducing process energy consumption is also a key point. In the technical solution of the present invention, the top temperature of the fourth distillation tower is about 20°C higher than the required temperature of the top of the third distillation tower, and the heat load of the top of the fourth distillation tower and the bottom of the third distillation tower are basically the same. Therefore, as a preferred technical solution of the present invention, the CDT extracted from the top of the fourth distillation tower is used as the heat source of the bottom of the third distillation tower, and the top discharge port of the fourth distillation tower is connected to the reboiler of the bottom of the third distillation tower through a pipeline, that is, the condenser at the top of the fourth distillation tower and the reboiler of the bottom of the third distillation tower are coupled into one device, which can reduce equipment investment, and save circulating water and steam consumption, thereby reducing energy consumption and reducing the overall process operation cost.

[0025] In the above technical solution, the solvent is one or more of cyclohexane, benzene, toluene, methylcyclohexane, cyclooctadiene, and cyclododecatriene.

[0026] The above technical scheme does not limit the internal structure of the distillation tower used; optionally, any one of the first distillation tower, the second distillation tower, the third distillation tower, the fourth distillation tower and the fifth distillation tower in the present invention may be provided with packing, trays or other internal parts or a combination of internal parts that can promote gas-liquid separation, and the technical scheme thus formed is within the protection scope of the present invention.

[0027] Specifically, on the other hand, the present invention provides a butadiene oligomerization reaction solvent recovery system, the system comprises a first distillation tower, a second distillation tower, a third distillation tower, and a fourth distillation tower, wherein

[0028] The first distillation tower is provided with a middle feed port, a top discharge port and a bottom discharge port, the middle feed port is used to input materials from the butadiene oligomerization reaction, and the bottom discharge port is connected to the middle feed port of the second distillation tower via a pipeline; the top discharge port of the second distillation tower is connected to the second condenser via a pipeline, the gas phase outlet of the second condenser is connected to the middle feed port of the third distillation tower via a pipeline, and the liquid phase outlet of the second condenser is connected to the top of the second distillation tower via a pipeline; the bottom discharge port of the second distillation tower is connected to the middle feed port of the fourth distillation tower via a pipeline; the third distillation tower is also provided with a top discharge port and a bottom discharge port; the fourth distillation tower is also provided with a top discharge port and a bottom discharge port.

[0029] The beneficial effects of the present invention are:

[0030] 1. Through the uniquely designed multi-stage vacuum distillation separation and purification of the materials after butadiene oligomerization reaction, COD and CDT products with a purity of not less than 99% are obtained; at the same time, unreacted butadiene and water can be effectively removed, so that the water content in the recovered solvent is less than 20ppm, ensuring the activity of the catalyst in the subsequent reaction system and promoting the efficient reaction; the solvent obtained by recycling is of high purity, and the solvent recovery rate reaches more than 99%, reducing the process cost.

[0031] 2. The butadiene oligomerization reaction solvent recovery process and system of the present invention can also produce high-purity tetravinylcyclohexene as a by-product.

[0032] 3. Thermal coupling treatment can save circulating water and steam consumption, significantly reducing the overall process operating costs in large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0034] Figure 1 It is a structural schematic diagram of a solvent recovery system for butadiene oligomerization reaction of the present invention;

[0035] Figure 2 Another structural schematic diagram of the butadiene oligomerization reaction solvent recovery system of the present invention.

[0036] The above drawings include the following reference numerals:

[0037] 1-first distillation tower, 11-first condenser, 12-first reboiler, 13-reflux tank, S14-first mixture, S15-second mixture, 2-second distillation tower, 21-second condenser, 22-second reboiler, S23-third mixture, S24-fourth mixture, S25-fifth mixture, S26-sixth mixture, 3-third distillation tower, 31-third condenser, 32-third reboiler, S33-seventh mixture, 4-fourth distillation tower, 41-fourth condenser, 42-fourth reboiler, 5-fifth distillation tower, 51-fifth condenser, 52-fifth reboiler. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be noted that in this embodiment, relational terms such as "first", "second", etc. are only used to distinguish one component with the same name from another, and do not necessarily require or imply any actual relationship or order between these components. Features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0039] Example 1

[0040] This embodiment proposes a butadiene oligomerization reaction solvent recovery system, and combines the system to describe in detail a butadiene oligomerization reaction solvent recovery process proposed by the present invention.

[0041] like Figure 1 As shown, the material to be purified from the butadiene oligomerization reaction is fed into the first distillation tower 1 from the middle feed port. After distillation in the first distillation tower 1, a first mixture S14 is extracted from the top of the tower, and the first mixture S14 is condensed by the first condenser 11 to obtain non-condensable gas, which is then discharged into the flare; the condensed liquid phase enters the reflux tank 13, and the water phase obtained after phase separation in the reflux tank 13 is discharged to sewage treatment, and the oil phase is returned to the top of the first distillation tower 1 as reflux. The bottom of the first distillation tower 1 is provided with a first reboiler 12. The second mixture S15 is extracted from the bottom of the first distillation tower 1, and the second mixture S15 enters the second distillation tower 2 for further distillation.

[0042] After the second mixture S15 is rectified by the second distillation tower 2, the third mixture S23 is extracted from the top of the tower. The third compound is cooled by the second condenser 21 to obtain a fourth mixture S24 in gas phase and a fifth mixture S25 in liquid phase. The fourth mixture S24 enters the third distillation tower 3, and the fifth mixture S25 is returned to the top of the second distillation tower 2 as reflux. The bottom of the second distillation tower 2 is provided with a second reboiler 22. The sixth mixture S26 is extracted from the bottom of the second distillation tower 2, and the sixth mixture S26 is input into the fourth distillation tower 4 for further distillation.

[0043] After the fourth mixture S24 is rectified by the third distillation tower 3, the top product is condensed by the third condenser 31 to obtain a solvent, and part of it is returned to the top of the third distillation tower 3 as reflux, and part of it is extracted as a circulating solvent. The bottom of the third distillation tower 3 is provided with a third reboiler 32. The seventh mixture S33 is extracted from the bottom of the third distillation tower 3.

[0044] After the sixth mixture S26 is rectified by the fourth distillation tower 4, the CDT extracted from the tower top is condensed by the fourth condenser 41, a part of which is returned to the tower top of the fourth distillation tower 4 as reflux, and a part of which is extracted as a CDT product and sent to the tank area. The fourth distillation tower 4 is provided with a fourth reboiler 42. The heavy component is extracted from the bottom of the fourth distillation tower 4.

[0045] In addition, a fifth distillation tower 5 is included. Specifically, after the seventh mixture S33 is distilled by the fifth distillation tower 5, a gas phase is extracted from the top of the tower; after the gas phase is condensed by the fifth condenser 51, a part of it is returned to the top of the fifth distillation tower 5 as reflux, and a part of it is extracted as a by-product tetravinylcyclohexene and sent to the tank area. The fifth distillation tower 5 is provided with a fifth reboiler 52 in the bottom of the tower.

[0046] Optionally, the first condenser 11 and the second condenser 21 are partial condensers, and the third condenser 31 , the fourth condenser 41 and the fifth condenser 51 are full condensers.

[0047] The present invention does not limit the type of reboiler. Any one of the first reboiler 12, the second reboiler 22, the third reboiler 32, the fourth reboiler 42 and the fifth reboiler 52 can be selected from one of a thermal siphon reboiler, a forced circulation reboiler, a falling film reboiler and a kettle reboiler.

[0048] Example 2

[0049] This embodiment proposes another butadiene oligomerization reaction solvent recovery system, the structure of which is the same as the system shown in Example 1, but a thermal coupling structure is provided. Figure 2 As shown, the top discharge port of the fourth distillation tower 4 is connected to the third reboiler 32 of the bottom of the third distillation tower 3 through a pipeline, that is, the CDT extracted from the top of the fourth distillation tower 4 is used as a heat source for vaporizing the bottom of the third distillation tower 3.

[0050] Examples 3-6 and Example 8 use the butadiene oligomerization reaction solvent recovery system shown in Example 1, and Example 7 uses the butadiene oligomerization reaction solvent recovery system shown in Example 2 to respectively demonstrate the butadiene oligomerization reaction solvent recovery process under specific working conditions. It should be noted that these process flows are only demonstrations of preferred processes and do not limit the scope of protection of the present invention.

[0051] Example 3

[0052] The composition of the material to be purified in this example is shown in Table 1. The solvent used is benzene, the target product is CDT, and the by-products are COD and tetravinylcyclohexene.

[0053] Table 1 Composition of the material to be purified in Example 3 (wt%)

[0054] composition Butadiene water Solvent (benzene) Tetravinylcyclohexene COD CDT Heavy components content 1% 500~5000ppm 22% 1% 1% 70% ≤5%

[0055] The operating parameters of each distillation column are shown in Table 2.

[0056] Table 2 Operating parameters of each distillation tower in Example 3

[0057] Serial number The first distillation tower 1 Second distillation tower 2 The third distillation tower 3 Fourth distillation tower 4 Fifth distillation tower 5 Operating pressure / kPaA 100~150 2~20 2~20 1~10 5~15 Tower top temperature / ℃ 10~30 10~60 10~30 100~120 20~60 Tower temperature / ℃ 100~150 120~180 60~100 150~180 80~120 Reflux ratio 1~10 1~5 1~5 0.2~2 5~10

[0058] The material to be purified is input into the butadiene oligomerization reaction solvent recovery system of the present invention from the middle feed port of the first distillation tower 1. After separation and purification, CDT with a purity of more than 99.5% is extracted from the top of the fourth distillation tower 4; solvent benzene with a water content of ≤20ppm is extracted from the top of the third distillation tower 3, and the solvent recovery rate calculated based on the flow rate of the solvent contained in the material to be purified and the flow rate of the solvent extracted from the top of the third distillation tower 3 is greater than 99%; tetravinylcyclohexene with a purity of more than 99% is extracted from the top of the fifth distillation tower 5, and COD with a purity of more than 99% is extracted from the bottom of the fifth distillation tower 5.

[0059] Example 4

[0060] The composition of the material to be purified in this example is shown in Table 3. The solvent used is methylcyclohexane, the target product is CDT, and the by-products are COD and tetravinylcyclohexene.

[0061] Table 3 Composition of the material to be purified in Example 4 (wt%)

[0062] composition Butadiene water Solvent (methylcyclohexane) Tetravinylcyclohexene COD CDT Heavy components content 1% 500~5000ppm 22% 1% 1% 70% ≤5%

[0063] The operating parameters of each distillation tower are shown in Table 4.

[0064] Table 4 Operating parameters of each distillation tower in Example 4

[0065] Serial number The first distillation tower 1 Second distillation tower 2 The third distillation tower 3 Fourth distillation tower 4 Fifth distillation tower 5 Operating pressure / kPaA 100~150 2~20 2~15 1~10 5~15 Tower top temperature / ℃ 10~30 40~60 40~60 100~120 40~60 Tower temperature / ℃ 120~150 150~180 60~100 150~180 80~120 Reflux ratio 1~10 3~5 3~5 0.2~2 5~10

[0066] The material to be purified is input into the butadiene oligomerization reaction solvent recovery system of the present invention from the middle feed port of the first distillation tower 1. After separation and purification, CDT with a purity of more than 99.5% is extracted from the top of the fourth distillation tower 4; solvent methylcyclohexane with a water content of ≤20ppm is extracted from the top of the third distillation tower 3, and the recovery rate of methylcyclohexane is greater than 99%; tetravinylcyclohexene with a purity of more than 99% is extracted from the top of the fifth distillation tower 5, and COD with a purity of more than 99% is extracted from the bottom of the fifth distillation tower 5.

[0067] Example 5

[0068] The composition of the material to be purified in this example is shown in Table 5. The solvent used is benzene, the target product is COD, and the by-products are CDT and tetravinylcyclohexene.

[0069] Table 5 Composition of the material to be purified in Example 5 (wt%)

[0070] composition Butadiene water Solvent (benzene) Tetravinylcyclohexene COD CDT Heavy components content ≤3% 500~5000ppm ≤30% ≤5% 55% ≤15% ≤5%

[0071] The operating parameters of each distillation tower are shown in Table 6.

[0072] Table 6 Operating parameters of each distillation tower in Example 5

[0073]

[0074] The material to be purified is input into the butadiene oligomerization reaction solvent recovery system of the present invention from the middle feed port of the first distillation tower 1. After separation and purification, COD with a purity of more than 99.5% is extracted from the bottom of the fifth distillation tower 5; solvent benzene with a water content of ≤20ppm is extracted from the top of the third distillation tower 3, and its recovery rate is greater than 99%; CDT with a purity of more than 99.5% is extracted from the top of the fourth distillation tower 4, and tetravinylcyclohexene with a purity of more than 99% is extracted from the top of the fifth distillation tower 5.

[0075] Example 6

[0076] The composition of the material to be purified in this example is shown in Table 7. The solvent used is toluene, the target product is CDT, and the by-products are COD and tetravinylcyclohexene.

[0077] Table 7 Composition of the material to be purified in Example 6 (wt%)

[0078] composition Butadiene water Solvent (Toluene) Tetravinylcyclohexene COD CDT Heavy components content ≤3% 500~5000ppm ≤30% ≤5% ≤5% ＞70% ≤5%

[0079] The operating parameters of each distillation tower are shown in Table 8.

[0080] Table 8 Operating parameters of each distillation tower in Example 6

[0081] Serial number The first distillation tower 1 Second distillation tower 2 The third distillation tower 3 Fourth distillation tower 4 Fifth distillation tower 5 Operating pressure / kPaA 100~200 5~20 5~15 1~10 5~15 Tower top temperature / ℃ 30~60 40~60 40~60 100~120 40~60 Tower temperature / ℃ 120~180 150~180 60~100 150~180 80~120 Reflux ratio 1~10 3~5 5~10 0.2~2 5~10

[0082] The material to be purified is input into the butadiene oligomerization reaction solvent recovery system of the present invention from the middle feed port of the first distillation tower 1. After separation and purification, CDT with a purity of more than 99.5% is extracted from the top of the fourth distillation tower 4; solvent toluene with a water content of ≤20ppm is extracted from the top of the third distillation tower 3, and the recovery rate of toluene is greater than 99%; tetravinylcyclohexene with a purity of more than 99% is extracted from the top of the fifth distillation tower 5, and COD with a purity of more than 99% is extracted from the bottom of the fifth distillation tower 5.

[0083] Example 7

[0084] This embodiment adopts the butadiene oligomerization reaction solvent recovery system shown in Example 2 for separation and purification. The composition of the material to be purified and the parameter settings of each distillation tower in this embodiment are the same as those shown in Example 6. After separation and purification, CDT with a purity of more than 99.5% is extracted from the top of the fourth distillation tower 4, solvent toluene with a water content of ≤20ppm is extracted from the top of the third distillation tower 3, tetravinylcyclohexene with a purity of more than 99% is extracted from the top of the fifth distillation tower 5, and COD with a purity of more than 99% is extracted from the bottom of the fifth distillation tower 5.

[0085] It can be seen from Example 6 that the temperature at the top of the fourth distillation tower 4 is more than 20°C higher than the temperature at the bottom of the third distillation tower 3, and the heat loads of the two are basically the same. Therefore, in this embodiment, the CDT steam at the top of the fourth distillation tower 4 is used as the heat source for the bottom of the third distillation tower 3, and the third condenser 31 and the fourth reboiler 42 are coupled into one device to reduce process energy consumption.

[0086] Take the production unit with an annual output of 50,000 tons of CDT as an example: the circulating water consumption at the top of the fourth distillation tower 4 is 98.75 t / h, and the steam consumption at the bottom of the third distillation tower 3 is 1.5 t / h. After thermal coupling, 12,000 tons of steam can be saved annually, and 790,000 tons of circulating water can be saved annually. Further calculated at 200 yuan / ton for steam and 0.2 yuan / ton for circulating water, the annual cost saving can reach 2.558 million yuan / year.

[0087] Example 8

[0088] The composition of the material to be purified in this example is shown in Table 9. The solvent used is a mixture of COD and tetravinylcyclohexene. The target product is CDT, and the by-products are COD and tetravinylcyclohexene.

[0089] Table 9 Composition of the material to be purified in Example 8 (wt%)

[0090] composition Butadiene water Tetravinylcyclohexene COD CDT Heavy components content ≤3% 500~5000ppm ≤5% ≤35% ＞70% ≤5%

[0091] The operating parameters of each distillation tower are shown in Table 10.

[0092] Table 10 Operating parameters of each distillation tower in Example 8

[0093] Serial number The first distillation tower 1 Second distillation tower 2 The third distillation tower 3 Fourth distillation tower 4 Fifth distillation tower 5 Operating pressure / kPaA 100~200 5~20 5~15 1~10 5~15 Tower top temperature / ℃ 30~60 50~100 50~100 100~120 40~60 Tower temperature / ℃ 120~200 150~180 50~100 150~180 80~120 Reflux ratio 1~10 3~5 5~10 0.2~2 5~10

[0094] The material to be purified is input into the butadiene oligomerization reaction solvent recovery system of the present invention from the middle feed port of the first distillation tower 1. After separation and purification, CDT with a purity of more than 99.5% is extracted from the top of the fourth distillation tower 4, and the solvent extracted from the top of the third distillation tower 3 is a mixture of COD and tetravinylcyclohexene (including 90wt% COD and 10wt% tetravinylcyclohexene), and the water content of the obtained solvent is ≤20ppm; tetravinylcyclohexene with a purity of more than 99% is extracted from the top of the fifth distillation tower 5, and COD with a purity of more than 99% is extracted from the bottom of the fifth distillation tower 5.

[0095] The above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple improvements and modifications can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A butadiene oligomerization solvent recovery process, characterized in that: It includes steps S1-S4, wherein Step S1: After the material to be purified from the butadiene oligomerization reaction is rectified by a first distillation tower (1), a first mixture (S14) is extracted from the top of the tower, and a second mixture (S15) is extracted from the bottom of the tower, and the second mixture (S15) enters step S2; the operating pressure of the first distillation tower (1) is 100-200 kPaA, the top temperature is 10-60°C, the bottom temperature is 100-200°C, and the mass reflux ratio is 1-20; the first mixture (S14) is subjected to fractional condensation treatment to obtain a non-condensable gas and a liquid phase, wherein the non-condensable gas is discharged into a flare, and the liquid phase is input into a reflux tank for phase separation to obtain an oil phase and a water phase, wherein the oil phase is returned to the top of the first distillation tower (1) as reflux, and the water phase is discharged to a sewage treatment unit; Step S2: After the second mixture (S15) is rectified in the second vacuum distillation tower (2), a third mixture (S23) is taken out from the top of the tower, and the third mixture is subjected to fractional condensation to obtain a fourth mixture (S24) in gas phase and a fifth mixture (S25) in liquid phase, and the fourth mixture (S24) enters step S3; a sixth mixture (S26) is taken out from the bottom of the second vacuum distillation tower (2), and the sixth mixture (S26) is input into step S4; Step S3: After the fourth mixture (S24) is rectified by the third vacuum distillation tower (3), the solvent is extracted from the top of the tower, and the seventh mixture (S33) is extracted from the bottom of the tower; Step S4: After the sixth mixture (S26) is distilled in the fourth vacuum distillation tower (4), CDT is taken out from the top of the tower, and heavy components are taken out from the bottom of the tower; The method further comprises step S5: after the seventh mixture (S33) is distilled in a fifth vacuum distillation tower (5), tetravinylcyclohexene is extracted from the tower top and COD is extracted from the tower bottom.

2. The butadiene oligomerization solvent recovery process according to claim 1, characterized in that: The operating pressure of the second vacuum distillation tower (2) is 2-50 kPaA; the tower top temperature is 10-100°C; the tower bottom temperature is 120-180°C; The mass reflux ratio is 1-10.

3. The butadiene oligomerization reaction solvent recovery process according to claim 2, characterized in that: The operating pressure of the second vacuum distillation tower (2) is 2-20 kPaA.

4. The butadiene oligomerization reaction solvent recovery process according to claim 2, characterized in that: The mass reflux ratio of the second vacuum distillation tower (2) is 1-5.

5. The butadiene oligomerization reaction solvent recovery process according to claim 1, characterized in that: The operating pressure of the third vacuum distillation tower (3) is 2-50 kPaA; the tower top temperature is 10-100°C; the tower bottom temperature is 60-120°C; The mass reflux ratio is 1-10.

6. The butadiene oligomerization reaction solvent recovery process according to claim 5, characterized in that: The third vacuum distillation tower (3) has a pressure of 2 to 18 kPaA.

7. The butadiene oligomerization reaction solvent recovery process according to claim 5, characterized in that: The bottom temperature of the third vacuum distillation tower (3) is 60-100°C.

8. The butadiene oligomerization solvent recovery process according to claim 5, characterized in that: The mass reflux ratio of the third vacuum distillation tower (3) is 1-5.

9. The butadiene oligomerization reaction solvent recovery process according to claim 1, characterized in that: The operating pressure of the fourth vacuum distillation tower (4) is 1-20 kPaA; the tower top temperature is 100-150°C; the tower bottom temperature is 150-180°C; The mass reflux ratio is 0.2-5.

10. The butadiene oligomerization reaction solvent recovery process according to claim 9, characterized in that: The operating pressure of the fourth vacuum distillation tower (4) is 1-10 kPaA.

11. The butadiene oligomerization solvent recovery process according to claim 9, characterized in that: The mass reflux ratio of the fourth vacuum distillation tower (4) is 0.2-2.

12. The butadiene oligomerization reaction solvent recovery process according to claim 1, characterized in that: The operating pressure of the fifth vacuum distillation tower (5) is 5-50 kPaA; the tower top temperature is 20-60°C; the tower bottom temperature is 80-150°C; and the mass reflux ratio is 5-50.

13. The butadiene oligomerization solvent recovery process according to claim 12, characterized in that: The operating pressure of the fifth vacuum distillation tower (5) is 5-15 kPaA.

14. The butadiene oligomerization solvent recovery process according to claim 12, characterized in that: The mass reflux ratio of the fifth vacuum distillation tower (5) is 5-10.

15. The butadiene oligomerization reaction solvent recovery process according to claim 1, characterized in that: The method also includes heat coupling treatment, wherein the CDT extracted from the top of the fourth vacuum distillation tower (4) is used as a heat source for vaporizing the bottom of the third vacuum distillation tower (3).

16. The butadiene oligomerization reaction solvent recovery process according to claim 1, characterized in that: The solvent is one or more of cyclohexane, benzene, toluene, methylcyclohexane, cyclooctadiene, and cyclododecatriene.

17. The butadiene oligomerization solvent recovery process according to claim 1, characterized in that: The process is carried out in the following device: the device comprises a first distillation tower (1), a second vacuum distillation tower (2), a third vacuum distillation tower (3), and a fourth vacuum distillation tower (4), wherein The first distillation tower (1) is provided with a middle feed inlet, a tower top discharge port and a tower bottom discharge port, wherein the middle feed inlet is used to input materials from butadiene oligomerization reaction, and the tower bottom discharge port is connected to the middle feed inlet of the second vacuum distillation tower (2) via a pipeline; The top discharge port of the second vacuum distillation tower (2) is connected to the second condenser (21) via a pipeline, the gas phase outlet of the second condenser (21) is connected to the middle feed port of the third vacuum distillation tower (3) via a pipeline, and the liquid phase outlet of the second condenser (21) is connected to the top of the second vacuum distillation tower (2) via a pipeline; the bottom discharge port of the second vacuum distillation tower (2) is connected to the middle feed port of the fourth vacuum distillation tower (4) via a pipeline; The third vacuum distillation tower (3) is also provided with a tower top discharge port and a tower bottom discharge port; The fourth vacuum distillation tower (4) is also provided with a tower top discharge port and a tower bottom discharge port.

18. The butadiene oligomerization reaction solvent recovery process according to claim 17, characterized in that: It also comprises a fifth vacuum distillation tower (5), wherein the bottom discharge port of the third vacuum distillation tower (3) is connected to the middle feed port of the fifth vacuum distillation tower (5) via a pipeline; the fifth vacuum distillation tower (5) is also provided with a top discharge port and a bottom discharge port.

19. The butadiene oligomerization reaction solvent recovery process according to claim 17, characterized in that: The top discharge port of the fourth vacuum distillation tower (4) is connected to the third reboiler (32) of the bottom of the third vacuum distillation tower (3) via a pipeline.

20. The butadiene oligomerization solvent recovery process according to claim 17, characterized in that: The top discharge port of the first distillation tower (1) is connected to the first condenser (11) via a pipeline; the first condenser (11) is a partial condenser, and the first condenser (11) is provided with a gas phase outlet and a liquid phase outlet, and the liquid phase outlet is connected to a reflux tank (13) via a pipeline; the reflux tank (13) is provided with a water phase and an oil phase outlet, wherein the oil phase outlet is connected to the top of the first distillation tower (1) via a pipeline.

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