Heavy component recycling system in isobutene preparation process

Abstract

The utility model provides a heavy component recycling system in an isobutene preparation process, which comprises a tertiary butanol catalytic distillation tower, an isobutene heavy component removal tower and a tertiary butanol extraction tower, the top of the tertiary butanol catalytic distillation tower is sequentially connected with a catalytic distillation tower condenser, a catalytic distillation tower return tank and an isobutene compressor; an outlet of the isobutene compressor is connected with an inlet in one side of the isobutene heavy component removal tower through a pipeline, the bottom of the isobutene heavy component removal tower is connected with the bottom of the tertiary butanol extraction tower through a pipeline, and the top of the isobutene heavy component removal tower is used for extracting high-purity isobutene; a return pipe of the tertiary butanol catalytic distillation tower is connected with an outlet of a demineralized water tank; an inlet of the demineralized water tank is connected with the bottom of the tertiary butanol extraction tower; demineralized water or sewage at the bottom of the tert-butyl alcohol catalytic distillation tower is collected from an inlet at the top of the tert-butyl alcohol extraction tower, and a purifier is arranged when the sewage at the bottom of the tower is collected. The system has the advantages of short flow, low investment, no additional energy consumption and high tertiary butanol recovery rate.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology, and in particular relates to a system for recycling heavy components in the preparation process of isobutylene. Background Technology

[0002] The catalytic distillation of tert-butanol to produce high-purity isobutylene is one of the commonly used processes for producing high-purity isobutylene. During the decomposition of tert-butanol to produce isobutylene and water, isobutylene undergoes dimerization and polymerization, forming dimers and polymers with higher boiling points. After separating the isobutylene product in a de-heavy fraction tower, the heavy fraction at the bottom of the tower contains 50%–70% tert-butanol, as well as water, C5, styrene, xylene, dimers, and polymers, resulting in a complex composition. Furthermore, tert-butanol and dimers form an azeotrope. Conventional distillation to recover tert-butanol from the heavy fraction suffers from long process times, high energy consumption, large investment costs, and low purity. Currently, this heavy fraction is commonly used as a fuel or heavy oil blending component, resulting in low economic efficiency. Utility Model Content

[0003] In view of this, the present invention aims to propose a system for recovering and utilizing heavy components in the preparation process of isobutylene, so as to solve the problems of long process, high energy consumption, large investment and low purity in the distillation recovery of tert-butanol from heavy components in the prior art.

[0004] To achieve the above objectives, the technical solution of this utility model is implemented as follows:

[0005] A heavy component recovery and utilization system in an isobutylene preparation process includes a tert-butanol catalytic distillation column, an isobutylene deweighting column, and a tert-butanol extraction column. A tert-butanol inlet pipeline is provided on one side of the tert-butanol catalytic distillation column, and a catalytic distillation column condenser, a catalytic distillation column reflux tank, and an isobutylene compressor are connected in sequence to the top of the tert-butanol catalytic distillation column.

[0006] The outlet of the isobutylene compressor is connected to the inlet on one side of the isobutylene de-weighting tower via a pipeline. The bottom of the isobutylene de-weighting tower is connected to the bottom of the tert-butanol extraction tower via a pipeline. The top of the isobutylene de-weighting tower is used to collect high-purity isobutylene.

[0007] The reflux pipe of the tert-butanol catalytic distillation column is connected to the outlet of the demineralized water tank, and the inlet of the demineralized water tank is connected to the bottom of the tert-butanol extraction column. Demineralized water is injected into the top of the tert-butanol catalytic distillation column as cold reflux to absorb the tert-butanol in the C4 at the top of the column.

[0008] The top inlet of the tert-butanol extraction tower is fed with demineralized water or wastewater from the bottom of the tert-butanol catalytic distillation tower. This invention utilizes demineralized water or wastewater from the bottom of the tert-butanol catalytic distillation tower to extract and recover tert-butanol from heavy components, thereby improving the utilization rate of tert-butanol and saving costs.

[0009] Furthermore, the tert-butanol catalytic distillation tower is provided with a tert-butanol inlet pipeline on one side and a wastewater outlet pipeline at the bottom of the tower. The top outlet of the tert-butanol catalytic distillation tower is connected to the condenser inlet of the catalytic distillation tower via a first pipeline. The condenser outlet is connected to the reflux tank inlet of the catalytic distillation tower via a second pipeline. The top outlet of the reflux tank is connected to the isobutylene compressor inlet via a third pipeline. The isobutylene compressor outlet is connected to the inlet on one side of the isobutylene de-weighting tower via a fourth pipeline. The bottom outlet of the reflux tank is connected to the reflux pump inlet of the catalytic distillation tower via a fifth pipeline. The reflux pump outlet is connected to the top inlet of the tert-butanol catalytic distillation tower via a sixth pipeline.

[0010] Furthermore, the top of the demineralized water tank is connected to a demineralized water intake pipeline, and the bottom of the demineralized water tank is connected to the sixth pipeline via a seventh pipeline.

[0011] Furthermore, a demineralized water pump is installed on the seventh pipeline.

[0012] The tert-butanol feedstock enters the tert-butanol catalytic distillation column through the tert-butanol inlet pipeline. Inside the tert-butanol catalytic distillation column, tert-butanol decomposes into isobutylene and water. After rectification by the tert-butanol catalytic distillation column, the gaseous material at the top of the column is mainly composed of isobutylene, with a small amount of tert-butanol. The gaseous material enters the condenser of the catalytic distillation column through the first pipeline and is condensed to 40°C. At this point, it is a two-phase gas-liquid mixture. The gas-liquid mixture flows by gravity into the reflux tank of the catalytic distillation column through the second pipeline. Gas-liquid separation occurs in the reflux tank. The gaseous material (isobutylene) enters the isobutylene compressor through the third pipeline, while the liquid material (tert-butanol and isobutylene mixture) is pressurized by the catalytic distillation column reflux pump, mixed with demineralized water, and then enters the top of the tert-butanol catalytic distillation column as reflux.

[0013] Furthermore, the bottom of the isobutylene deweighting tower is connected to the heavy component extraction pipeline, the top outlet of the isobutylene deweighting tower is connected to the inlet of the isobutylene deweighting tower condenser through the eighth pipeline, the outlet of the isobutylene deweighting tower condenser is connected to the inlet of the isobutylene deweighting tower reflux tank through the ninth pipeline, the outlet of the isobutylene deweighting tower reflux tank is connected to the inlet of the isobutylene deweighting tower reflux pump through the tenth pipeline, and the outlet of the isobutylene deweighting tower reflux pump is connected to the top inlet of the isobutylene deweighting tower through the eleventh pipeline.

[0014] The eleventh pipeline is connected to the high-purity isobutylene extraction pipeline.

[0015] The gaseous material (isobutylene) from the isobutylene compressor outlet enters the isobutylene de-weighting tower via the fourth pipeline. The bottom of the isobutylene de-weighting tower contains heavy components, which then enter the tert-butanol extraction tower. The top of the isobutylene de-weighting tower contains gaseous high-purity isobutylene. The high-purity isobutylene enters the isobutylene de-weighting tower condenser via the eighth pipeline and is condensed to 40°C, at which point it becomes a liquid phase. The liquid phase flows by gravity through the ninth pipeline into the isobutylene de-weighting tower reflux tank. The liquid phase in the isobutylene de-weighting tower reflux tank is pressurized by the isobutylene de-weighting tower reflux pump. Part of it enters the top of the isobutylene de-weighting tower as reflux, and the other part is collected as high-purity isobutylene product.

[0016] Furthermore, the bottom inlet of the tert-butanol extraction tower is connected to the heavy component extraction pipeline, the bottom outlet of the tert-butanol extraction tower is connected to the inlet of the demineralized water tank through the twelfth pipeline, and the top outlet of the tert-butanol extraction tower is connected to the oil phase extraction pipeline.

[0017] Furthermore, when demineralized water is introduced into the top inlet of the tert-butanol extraction tower, a thirteenth pipeline is connected to the demineralized water inlet pipeline, and the outlet of the thirteenth pipeline is connected to the top inlet of the tert-butanol extraction tower.

[0018] Furthermore, when the wastewater from the bottom of the tert-butanol catalytic distillation tower is collected at the top inlet of the tert-butanol extraction tower, a fourteenth pipeline is connected to the wastewater collection pipeline, and the outlet of the fourteenth pipeline is connected to the top inlet of the tert-butanol extraction tower.

[0019] The heavy components are pressurized from the bottom of the isobutylene de-removal tower and then from the bottom of the tert-butanol extraction tower into the tert-butanol extraction tower. All or part of the demineralized water or wastewater from the bottom of the tert-butanol catalytic distillation tower enters from the top of the tert-butanol extraction tower. Tert-butanol is soluble in water, while dimers and other hydrocarbons are insoluble in water. The heavy components flowing from bottom to top and the demineralized water or wastewater from the bottom of the tert-butanol catalytic distillation tower flowing from top to bottom come into countercurrent contact on the packing in the tert-butanol extraction tower. The tert-butanol in the heavy components enters the aqueous phase to obtain a tert-butanol aqueous solution. The tert-butanol aqueous solution flows out from the bottom of the tert-butanol extraction tower and enters the demineralized water tank. After being pressurized by the demineralized water pump, it continues to enter the top of the tert-butanol catalytic distillation tower. The recovered tert-butanol continues to participate in the reaction in the tert-butanol catalytic distillation tower, and the oil phase is collected from the top of the tert-butanol extraction tower.

[0020] The demineralized water entering the top of the tert-butanol catalytic distillation column or the wastewater entering the bottom of the tert-butanol catalytic distillation column is used to extract and recover tert-butanol from the heavy components. The system's own material water is used as the extractant, eliminating the need to introduce other extractants and saving costs.

[0021] Furthermore, a purifier is installed on the fourteenth pipeline. The catalyst in the tert-butanol catalytic distillation tower is an acidic resin catalyst. Some of the sulfonic acid groups will be removed as the reaction proceeds. The removed sulfonic acid groups enter the wastewater at the bottom of the tower, causing the wastewater to be strongly acidic. Therefore, the wastewater is treated by the purifier before entering the tert-butanol extraction tower, which greatly reduces the problem of equipment and pipeline corrosion.

[0022] Compared with existing technologies, the heavy component recycling system in the isobutylene preparation process described in this utility model has the following advantages:

[0023] (1) This utility model adds a tert-butanol extraction tower, which uses the demineralized water at the top of the tert-butanol catalytic distillation tower or the wastewater at the bottom of the tert-butanol catalytic distillation tower to extract and recover tert-butanol from the heavy components. It uses the system's own material water as the extractant, without the need to introduce other extractants, which saves costs and has a short process and low investment.

[0024] (2) The materials entering and exiting the tert-butanol extraction tower of this utility model are self-pressurized or utilize the original pressure system, without the need for additional power facilities such as pumps, and without any additional energy consumption.

[0025] (3) The system described in this utility model improves the utilization rate of tert-butanol and effectively recovers tert-butanol, with a recovery rate of over 96%.

[0026] (4) When the wastewater at the bottom of the tert-butanol catalytic distillation tower is used as the extractant, a purifier is set up to purify the acidic wastewater, which greatly reduces the problem of equipment and pipeline corrosion. When demineralized water is used as the extractant, the demineralized water passes through the purifier without purification, and the process operation is flexible. Attached Figure Description

[0027] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0028] Figure 1 This is a schematic diagram of a heavy component recycling system in an isobutylene preparation process according to Embodiment 1 of this utility model;

[0029] Figure 2 This is a schematic diagram of a heavy component recycling system in an isobutylene preparation process as described in Embodiment 2 of this utility model.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. First pipeline; 2. Second pipeline; 3. Third pipeline; 4. Fourth pipeline; 5. Fifth pipeline; 6. Sixth pipeline; 7. Seventh pipeline; 8. Eighth pipeline; 9. Ninth pipeline; 10. Tenth pipeline; 11. Eleventh pipeline; 12. Twelfth pipeline; 13. Thirteenth pipeline; 14. Fourteenth pipeline; 15. Tert-butanol catalytic distillation column; 16. Isobutylene deweighting column; 17. Tert-butanol extraction column; 18. Tert-butanol inlet pipeline; 19. Catalytic distillation... 20. Catalytic distillation column condenser; 21. Catalytic distillation column reflux tank; 22. Isobutylene compressor; 23. Demineralized water tank; 24. Wastewater collection pipeline; 25. Catalytic distillation column reflux pump; 26. Demineralized water intake pipeline; 27. Demineralized water pump; 28. Heavy component collection pipeline; 29. ​​Isobutylene deweighting column condenser; 30. Isobutylene deweighting column reflux tank; 31. Isobutylene deweighting column reflux pump; 32. High-purity isobutylene collection pipeline; 33. Oil phase collection pipeline; 34. Purifier. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0033] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0034] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Example 1

[0037] A system for recovering and utilizing heavy components in an isobutylene preparation process includes a tert-butanol catalytic distillation column 15, an isobutylene deweighting column 16, and a tert-butanol extraction column 17. A tert-butanol inlet pipeline 18 is provided on one side of the tert-butanol catalytic distillation column 15. A catalytic distillation column condenser 19, a catalytic distillation column reflux tank 20, and an isobutylene compressor 21 are connected in sequence to the top of the tert-butanol catalytic distillation column 15.

[0038] The outlet of the isobutylene compressor 21 is connected to the inlet on one side of the isobutylene de-weighting tower 16 via a pipeline. The bottom of the isobutylene de-weighting tower 16 is connected to the bottom of the tert-butanol extraction tower 17 via a pipeline. The top of the isobutylene de-weighting tower 16 is used to collect high-purity isobutylene.

[0039] The top of the tert-butanol catalytic distillation column 15 is connected to a demineralized water tank 22. The outlet of the demineralized water tank 22 is connected to the bottom outlet of the catalytic distillation column reflux tank 20. The inlet of the demineralized water tank 22 is connected to the bottom of the tert-butanol extraction column 17. Demineralized water is injected into the top of the tert-butanol catalytic distillation column 15 as cold reflux to absorb the tert-butanol in the C4 at the top of the column.

[0040] Demineralized water is introduced at the top inlet of tert-butanol extraction tower 17. This invention uses demineralized water to extract and recover tert-butanol from heavy components, thereby improving the utilization rate of tert-butanol and saving costs.

[0041] The tert-butanol catalytic distillation column 15 is provided with a tert-butanol inlet pipe 18 on one side and a wastewater outlet pipe 23 at the bottom of the column. The top outlet of the tert-butanol catalytic distillation column 15 is connected to the inlet of the catalytic distillation column condenser 19 via a first pipe 1. The outlet of the catalytic distillation column condenser 19 is connected to the inlet of the catalytic distillation column reflux tank 20 via a second pipe 2. The top outlet of the catalytic distillation column reflux tank 20 is connected to the inlet of the isobutylene compressor 21 via a third pipe 3. The outlet of the isobutylene compressor 21 is connected to the inlet on one side of the isobutylene de-weighting column 16 via a fourth pipe 4. The bottom outlet of the catalytic distillation column reflux tank 20 is connected to the inlet of the catalytic distillation column reflux pump 24 via a fifth pipe 5. The outlet of the catalytic distillation column reflux pump 24 is connected to the top inlet of the tert-butanol catalytic distillation column 15 via a sixth pipe 6.

[0042] The top of the demineralized water tank 22 is connected to the demineralized water intake pipe 25, and the bottom of the demineralized water tank 22 is connected to the sixth pipe 6 through the seventh pipe 7.

[0043] The seventh pipeline 7 is equipped with a demineralized water pump 26.

[0044] The tert-butanol feedstock enters the tert-butanol catalytic distillation column 15 through the tert-butanol inlet pipe 18. Inside the tert-butanol catalytic distillation column 15, tert-butanol decomposes into isobutylene and water. After distillation in the tert-butanol catalytic distillation column 15, the gaseous material at the top of the column is mainly composed of isobutylene, with a small amount of tert-butanol. The gaseous material enters the catalytic distillation column condenser 19 through the first pipe 1 and is condensed to 40°C. At this point, it is a two-phase gas-liquid mixture. The gas-liquid mixture flows by gravity into the catalytic distillation column reflux tank 20 through the second pipe 2. Gas-liquid separation is carried out in the catalytic distillation column reflux tank 20. The gaseous material (isobutylene) enters the isobutylene compressor 21 through the third pipe 3. The liquid material (tert-butanol and isobutylene mixture) is pressurized by the catalytic distillation column reflux pump 24, mixed with demineralized water, and then enters the top of the tert-butanol catalytic distillation column 15 as reflux.

[0045] The bottom of the isobutylene deweighting tower 16 is connected to the heavy component extraction pipeline 27. The top outlet of the isobutylene deweighting tower 16 is connected to the inlet of the isobutylene deweighting tower condenser 28 through the eighth pipeline 8. The outlet of the isobutylene deweighting tower condenser 28 is connected to the inlet of the isobutylene deweighting tower reflux tank 29 through the ninth pipeline 9. The outlet of the isobutylene deweighting tower reflux tank 29 is connected to the inlet of the isobutylene deweighting tower reflux pump 30 through the tenth pipeline 10. The outlet of the isobutylene deweighting tower reflux pump 30 is connected to the top inlet of the isobutylene deweighting tower 16 through the eleventh pipeline 11.

[0046] The eleventh pipeline 11 is connected to the high-purity isobutylene extraction pipeline 31.

[0047] The gaseous material (isobutylene) from the outlet of the isobutylene compressor 21 enters the isobutylene de-weighting tower 16 via the fourth pipeline 4. The bottom of the isobutylene de-weighting tower 16 contains heavy components, which enter the tert-butanol extraction tower 17. The top of the isobutylene de-weighting tower 16 contains gaseous high-purity isobutylene. The high-purity isobutylene enters the isobutylene de-weighting tower condenser 28 via the eighth pipeline 8 and is condensed to 40°C, at which point it is in the liquid phase. The liquid phase flows by gravity through the ninth pipeline 9 into the isobutylene de-weighting tower reflux tank 29. The liquid phase in the isobutylene de-weighting tower reflux tank 29 is pressurized by the isobutylene de-weighting tower reflux pump 30. Part of it enters the top of the isobutylene de-weighting tower 16 as reflux, and part of it is collected as high-purity isobutylene product.

[0048] The bottom inlet of the tert-butanol extraction tower 17 is connected to the heavy component extraction pipeline 27, the bottom outlet of the tert-butanol extraction tower 17 is connected to the inlet of the demineralized water tank 22 through the twelfth pipeline 12, and the top outlet of the tert-butanol extraction tower 17 is connected to the oil phase extraction pipeline 32.

[0049] The demineralized water intake pipeline 25 is connected to the thirteenth pipeline 13, and the outlet of the thirteenth pipeline 13 is connected to the top inlet of the tert-butanol extraction tower 17.

[0050] The heavy components enter the tert-butanol extraction tower 17 from the bottom of the isobutylene de-removal tower 16 under pressure. All or part of the demineralized water enters from the top of the tert-butanol extraction tower 17. Tert-butanol is soluble in water, while dimers and other hydrocarbons are insoluble in water. The heavy components flowing from bottom to top and the demineralized water flowing from top to bottom come into countercurrent contact on the packing in the tert-butanol extraction tower 17. The tert-butanol in the heavy components enters the aqueous phase to obtain a tert-butanol aqueous solution. The tert-butanol aqueous solution flows out from the bottom of the tert-butanol extraction tower 17 and enters the demineralized water tank 22. After being pressurized by the demineralized water pump 26, it continues to enter the top of the tert-butanol catalytic distillation tower 15. The recovered tert-butanol continues to participate in the reaction in the tert-butanol catalytic distillation tower 15, and the oil phase is collected from the top of the tert-butanol extraction tower 17.

[0051] The demineralized water entering the top of the tert-butanol catalytic distillation column 15 is used to extract and recover tert-butanol from the heavy components. The system's own water is used as the extractant, eliminating the need to introduce other extractants and saving costs.

[0052] Taking a 20,000-ton / year tert-butanol to high-purity isobutylene process as an example (scale is based on the amount of high-purity isobutylene produced), the heavy components in the tert-butanol to high-purity isobutylene process are fed into the tert-butanol extraction tower 17 from the bottom under self-pressure, with a feed rate of 250 kg / h, a feed temperature of 40℃, and a feed pressure of 0.4 MPaG. Demineralized water is fed into the tert-butanol extraction tower 17 at 100% load (1000 kg / h). The extraction tower operates at 40℃, with a top pressure of 0.25 MPaG and a bottom pressure of 0.35 MPaG. The extraction tower has a diameter of 250 mm and a height of 9200 mm, and is filled with random-packed stainless steel packing. The tert-butanol recovery rate is 98%. The tert-butanol in the heavy components enters the aqueous phase, which is the tert-butanol aqueous solution at the bottom of the tower that flows by gravity into the demineralized water tank 22. It is then pressurized by the demineralized water pump 26 and sent to the top of the tert-butanol catalytic distillation tower 15. The oil phase overflows from the top of the tert-butanol extraction tower 17 and is pressurized to the heavy component tank area. The composition of the materials entering and leaving the tert-butanol extraction tower 17 is shown in Table 1.

[0053] Table 1. Composition of materials in the tert-butanol extraction tower of Example 1

[0054]

[0055]

[0056] Example 1: The total investment in new equipment, instruments, pipelines, etc. was 95,000 yuan. The recovery rate of tert-butanol was 98%, which greatly improved the utilization rate of tert-butanol and saved costs.

[0057] Example 2

[0058] A system for recovering and utilizing heavy components in an isobutylene preparation process includes a tert-butanol catalytic distillation column 15, an isobutylene deweighting column 16, and a tert-butanol extraction column 17. A tert-butanol inlet pipeline 18 is provided on one side of the tert-butanol catalytic distillation column 15. A catalytic distillation column condenser 19, a catalytic distillation column reflux tank 20, and an isobutylene compressor 21 are connected in sequence to the top of the tert-butanol catalytic distillation column 15.

[0059] The outlet of the isobutylene compressor 21 is connected to the inlet on one side of the isobutylene de-weighting tower 16 via a pipeline. The bottom of the isobutylene de-weighting tower 16 is connected to the bottom of the tert-butanol extraction tower 17 via a pipeline. The top of the isobutylene de-weighting tower 16 is used to collect high-purity isobutylene.

[0060] The top of the tert-butanol catalytic distillation column 15 is connected to a demineralized water tank 22. The outlet of the demineralized water tank 22 is connected to the bottom outlet of the catalytic distillation column reflux tank 20. The inlet of the demineralized water tank 22 is connected to the bottom of the tert-butanol extraction column 17. Demineralized water is injected into the top of the tert-butanol catalytic distillation column 15 as cold reflux to absorb the tert-butanol in the C4 at the top of the column.

[0061] Wastewater from the bottom of the tert-butanol catalytic distillation tower is collected at the top inlet of the tert-butanol extraction tower 17. This invention uses the wastewater from the bottom of the tert-butanol catalytic distillation tower 15 to extract and recover tert-butanol from the heavy components, thereby improving the utilization rate of tert-butanol and saving costs.

[0062] The tert-butanol catalytic distillation column 15 is provided with a tert-butanol inlet pipe 18 on one side and a wastewater outlet pipe 23 at the bottom of the column. The top outlet of the tert-butanol catalytic distillation column 15 is connected to the inlet of the catalytic distillation column condenser 19 via a first pipe 1. The outlet of the catalytic distillation column condenser 19 is connected to the inlet of the catalytic distillation column reflux tank 20 via a second pipe 2. The top outlet of the catalytic distillation column reflux tank 20 is connected to the inlet of the isobutylene compressor 21 via a third pipe 3. The outlet of the isobutylene compressor 21 is connected to the inlet on one side of the isobutylene de-weighting column 16 via a fourth pipe 4. The bottom outlet of the catalytic distillation column reflux tank 20 is connected to the inlet of the catalytic distillation column reflux pump 24 via a fifth pipe 5. The outlet of the catalytic distillation column reflux pump 24 is connected to the top inlet of the tert-butanol catalytic distillation column 15 via a sixth pipe 6.

[0063] The top of the demineralized water tank 22 is connected to the demineralized water intake pipe 25, and the bottom of the demineralized water tank 22 is connected to the sixth pipe 6 through the seventh pipe 7.

[0064] The seventh pipeline 7 is equipped with a demineralized water pump 26.

[0065] The tert-butanol feedstock enters the tert-butanol catalytic distillation column 15 through the tert-butanol inlet pipe 18. Inside the tert-butanol catalytic distillation column 15, tert-butanol decomposes into isobutylene and water. After distillation in the tert-butanol catalytic distillation column 15, the gaseous material at the top of the column is mainly composed of isobutylene, with a small amount of tert-butanol. The gaseous material enters the catalytic distillation column condenser 19 through the first pipe 1 and is condensed to 40°C. At this point, it is a two-phase gas-liquid mixture. The gas-liquid mixture flows by gravity into the catalytic distillation column reflux tank 20 through the second pipe 2. Gas-liquid separation is carried out in the catalytic distillation column reflux tank 20. The gaseous material (isobutylene) enters the isobutylene compressor 21 through the third pipe 3. The liquid material (tert-butanol and isobutylene mixture) is pressurized by the catalytic distillation column reflux pump 24, mixed with demineralized water, and then enters the top of the tert-butanol catalytic distillation column 15 as reflux.

[0066] The bottom of the isobutylene deweighting tower 16 is connected to the heavy component extraction pipeline 27. The top outlet of the isobutylene deweighting tower 16 is connected to the inlet of the isobutylene deweighting tower condenser 28 through the eighth pipeline 8. The outlet of the isobutylene deweighting tower condenser 28 is connected to the inlet of the isobutylene deweighting tower reflux tank 29 through the ninth pipeline 9. The outlet of the isobutylene deweighting tower reflux tank 29 is connected to the inlet of the isobutylene deweighting tower reflux pump 30 through the tenth pipeline 10. The outlet of the isobutylene deweighting tower reflux pump 30 is connected to the top inlet of the isobutylene deweighting tower 16 through the eleventh pipeline 11.

[0067] The eleventh pipeline 11 is connected to the high-purity isobutylene extraction pipeline 31.

[0068] The gaseous material (isobutylene) from the outlet of the isobutylene compressor 21 enters the isobutylene de-weighting tower 16 via the fourth pipeline 4. The bottom of the isobutylene de-weighting tower 16 contains heavy components, which enter the tert-butanol extraction tower 17. The top of the isobutylene de-weighting tower 16 contains gaseous high-purity isobutylene. The high-purity isobutylene enters the isobutylene de-weighting tower condenser 28 via the eighth pipeline 8 and is condensed to 40°C, at which point it is in the liquid phase. The liquid phase flows by gravity through the ninth pipeline 9 into the isobutylene de-weighting tower reflux tank 29. The liquid phase in the isobutylene de-weighting tower reflux tank 29 is pressurized by the isobutylene de-weighting tower reflux pump 30. Part of it enters the top of the isobutylene de-weighting tower 16 as reflux, and part of it is collected as high-purity isobutylene product.

[0069] The bottom inlet of the tert-butanol extraction tower 17 is connected to the heavy component extraction pipeline 27, the bottom outlet of the tert-butanol extraction tower 17 is connected to the inlet of the demineralized water tank 22 through the twelfth pipeline 12, and the top outlet of the tert-butanol extraction tower 17 is connected to the oil phase extraction pipeline 32.

[0070] The wastewater collection pipeline 23 is connected to the fourteenth pipeline 14, and the outlet of the fourteenth pipeline 14 is connected to the top inlet of the tert-butanol extraction tower 17.

[0071] The heavy components enter the tert-butanol extraction tower 17 from the bottom of the isobutylene de-removal tower 16 under pressure. All or part of the wastewater from the bottom of the tert-butanol catalytic distillation tower 15 enters the tert-butanol extraction tower 17 from the top. Tert-butanol is soluble in water, while dimers and other hydrocarbons are insoluble in water. The heavy components flowing upward and the wastewater from the bottom of the tert-butanol catalytic distillation tower 15 flowing downward come into countercurrent contact on the packing in the tert-butanol extraction tower 17. The tert-butanol in the heavy components enters the aqueous phase to obtain a tert-butanol aqueous solution. The tert-butanol aqueous solution flows out from the bottom of the tert-butanol extraction tower 17 and enters the demineralized water tank 22. After being pressurized by the demineralized water pump 26, it continues to enter the top of the tert-butanol catalytic distillation tower 15. The recovered tert-butanol continues to participate in the reaction in the tert-butanol catalytic distillation tower 15, and the oil phase is collected from the top of the tert-butanol extraction tower 17.

[0072] The wastewater at the bottom of the 15th column of the tert-butanol catalytic distillation tower is used to extract and recover tert-butanol from the heavy components. The system's own material water is used as the extractant, eliminating the need to introduce other extractants and saving costs.

[0073] The fourteenth pipeline 14 is equipped with a purifier 33. The catalyst in the tert-butanol catalytic distillation tower 15 is an acidic resin catalyst. Some of the sulfonic acid groups will be removed as the reaction proceeds. The removed sulfonic acid groups enter the wastewater at the bottom of the tower, making the wastewater strongly acidic. Therefore, the wastewater is treated by the purifier 33 before entering the tert-butanol extraction tower 17, which greatly reduces the problem of equipment and pipeline corrosion.

[0074] Taking a 20,000-ton / year tert-butanol to high-purity isobutylene process as an example (scale is based on the amount of high-purity isobutylene produced), in the tert-butanol to high-purity isobutylene process, the heavy components enter the tert-butanol extraction tower 17 from the bottom under self-pressure, with a feed rate of 250 kg / h, a feed temperature of 40℃, and a feed pressure of 0.4 MPaG. Wastewater from the bottom of the tert-butanol catalytic distillation tower 15, at a rate of 1001.5 kg / h, is purified by purifier 33 and then enters the tert-butanol extraction tower 17 from the top. The extraction tower operates at a temperature of 40℃, with a top pressure of 0.25 MPaG and a bottom pressure of 0.35 MPaG. The extraction tower has a diameter of 250 mm and a height of 9200 mm, and is filled with randomly packed stainless steel packing. The tert-butanol recovery rate is 96.3%, and corrosion of subsequent wastewater pipelines and the tert-butanol extraction tower 17 is significantly reduced. The tert-butanol in the heavy components enters the aqueous phase, which is the tert-butanol aqueous solution at the bottom of the tower that flows by gravity into the demineralized water tank 22. It is then pressurized by the demineralized water pump 26 and sent to the top of the tert-butanol catalytic distillation tower 15. The oil phase overflows from the top of the tert-butanol extraction tower 17 and is pressurized to the heavy component tank area. The composition of the materials entering and leaving the tert-butanol extraction tower 17 is shown in Table 2.

[0075] Table 2. Composition of materials in the tert-butanol extraction tower of Example 2

[0076]

[0077]

[0078] Example 2: The total investment in new equipment, instruments, pipelines, etc. was 95,000 yuan. The recovery rate of tert-butanol was 96.3%, which greatly improved the utilization rate of tert-butanol and saved costs.

[0079] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A system for recycling heavy components in an isobutylene preparation process, characterized in that: It includes a tert-butanol catalytic distillation column (15), an isobutylene deweighting column (16), and a tert-butanol extraction column (17). The tert-butanol catalytic distillation column (15) is provided with a tert-butanol inlet pipeline (18) on one side. The top of the tert-butanol catalytic distillation column (15) is connected in sequence to a catalytic distillation column condenser (19), a catalytic distillation column reflux tank (20), and an isobutylene compressor (21). The outlet of the isobutylene compressor (21) is connected to the inlet on one side of the isobutylene de-weighting tower (16) through a pipeline. The bottom of the isobutylene de-weighting tower (16) is connected to the bottom of the tert-butanol extraction tower (17) through a pipeline. The top of the isobutylene de-weighting tower (16) is used to collect high-purity isobutylene. The reflux pipe of the tert-butanol catalytic distillation column (15) is connected to the outlet of the demineralized water tank (22), and the inlet of the demineralized water tank (22) is connected to the bottom of the tert-butanol extraction column (17); Demineralized water is collected at the top inlet of the tert-butanol extraction tower (17) or wastewater is collected at the bottom of the tert-butanol catalytic distillation tower (15).

2. The heavy component recycling system in the isobutylene preparation process according to claim 1, characterized in that: The tert-butanol catalytic distillation tower (15) is provided with a tert-butanol inlet pipe (18) on one side and a wastewater outlet pipe (23) at the bottom of the tert-butanol catalytic distillation tower (15). The top outlet of the tert-butanol catalytic distillation tower (15) is connected to the inlet of the catalytic distillation tower condenser (19) through the first pipe (1). The outlet of the catalytic distillation tower condenser (19) is connected to the inlet of the catalytic distillation tower reflux tank (20) through the second pipe (2). The top outlet of the catalytic distillation tower reflux tank (20) is connected to the inlet of the isobutylene compressor (21) through the third pipe (3). The outlet of the isobutylene compressor (21) is connected to the inlet on one side of the isobutylene de-weighting tower (16) through the fourth pipe (4). The bottom outlet of the catalytic distillation tower reflux tank (20) is connected to the inlet of the catalytic distillation tower reflux pump (24) through the fifth pipe (5). The outlet of the catalytic distillation tower reflux pump (24) is connected to the top inlet of the tert-butanol catalytic distillation tower (15) through the sixth pipe (6).

3. The heavy component recycling system in the isobutylene preparation process according to claim 1, characterized in that: The top of the demineralized water tank (22) is connected to the demineralized water intake pipeline (25), and the bottom of the demineralized water tank (22) is connected to the sixth pipeline (6) through the seventh pipeline (7).

4. The heavy component recycling system in the isobutylene preparation process according to claim 3, characterized in that: The seventh pipeline (7) is equipped with a demineralized water pump (26).

5. The heavy component recycling system in the isobutylene preparation process according to claim 1, characterized in that: The bottom of the isobutylene deweighting tower (16) is connected to the heavy component extraction pipeline (27). The top outlet of the isobutylene deweighting tower (16) is connected to the inlet of the isobutylene deweighting tower condenser (28) through the eighth pipeline (8). The outlet of the isobutylene deweighting tower condenser (28) is connected to the inlet of the isobutylene deweighting tower reflux tank (29) through the ninth pipeline (9). The outlet of the isobutylene deweighting tower reflux tank (29) is connected to the inlet of the isobutylene deweighting tower reflux pump (30) through the tenth pipeline (10). The outlet of the isobutylene deweighting tower reflux pump (30) is connected to the top inlet of the isobutylene deweighting tower (16) through the eleventh pipeline (11). The high-purity isobutylene extraction pipeline (31) is connected to the eleventh pipeline (11).

6. The heavy component recycling system in the isobutylene preparation process according to claim 1, characterized in that: The bottom inlet of the tert-butanol extraction tower (17) is connected to the heavy component extraction pipeline (27), the bottom outlet of the tert-butanol extraction tower (17) is connected to the inlet of the demineralized water tank (22) through the twelfth pipeline (12), and the top outlet of the tert-butanol extraction tower (17) is connected to the oil phase extraction pipeline (32).

7. The heavy component recycling system in the isobutylene preparation process according to claim 1, characterized in that: When demineralized water is collected at the top inlet of the tert-butanol extraction tower (17), the thirteenth pipeline (13) is connected to the demineralized water collection pipeline (25), and the outlet of the thirteenth pipeline (13) is connected to the top inlet of the tert-butanol extraction tower (17).

8. The heavy component recycling system in the isobutylene preparation process according to claim 1, characterized in that: When the wastewater from the bottom of the tert-butanol catalytic distillation tower (15) is collected at the top inlet of the tert-butanol extraction tower (17), the wastewater collection pipeline (23) is connected to the fourteenth pipeline (14), and the outlet of the fourteenth pipeline (14) is connected to the top inlet of the tert-butanol extraction tower (17).

9. A heavy component recycling system in an isobutylene preparation process according to claim 8, characterized in that: A purifier (33) is installed on the fourteenth pipeline (14).

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