Device for co-production of high-purity mtbe and 1-butene by using poor isobutene mixed carbon four as raw material

Abstract

The utility model relates to the technical field of coal chemical industry, concretely is the device of high purity MTBE and 1 - butene's coproduction with poor isobutene mixed carbon four as raw material. The device of high purity MTBE and 1 - butene's coproduction with poor isobutene mixed carbon four as raw material, including etherification reactor, etherification reactor is connected with carbon four water washing tower through catalytic rectifying column, catalytic rectifying column is connected with the heat exchanger of 1 - butene refining feed and the heat exchanger of around pipe heat exchanger through carbon four water washing tower, around pipe heat exchanger is connected with isomerization reactor through electric heater, isomerization reactor is connected with the heat exchanger of 1 - butene refining feed through around pipe heat exchanger, around pipe heat exchanger is connected with the compressor buffer tank through the heat exchanger of 1 - butene refining feed. The device greatly improved the effective concentration of isobutene in the raw material into etherification unit, fundamentally solved the bottleneck of low isobutene content of raw material.

Description

Technical Field

[0001] This utility model relates to the field of coal chemical technology, specifically to an apparatus for the co-production of high-purity MTBE and 1-butene using a mixture of low-isobutylene and C4 as raw materials. Background Technology

[0002] In the mixed C4 byproducts of MTO (methanol-to-olefins) plants, the isobutylene content is typically low (2-5 wt%), while the n-butene content (including 1-butene and 2-butene) is as high as 85-90 wt%. In existing technologies, isobutylene is usually converted to MTBE via etherification, followed by separation and purification of 1-butene. However, existing production facilities suffer from numerous structural defects.

[0003] Traditional equipment typically employs a linear process, where separation occurs directly after etherification. For isobutylene-poor feedstocks, after complete isobutylene reaction, the majority of components, such as 2-butene, cannot be effectively converted within existing equipment structures. Most are burned as low-value liquefied gas or fuel, limiting the overall atom economy and economic efficiency of the equipment. There is a lack of structural design to convert low-value components into high-value feedstocks and return them to the upstream of the process.

[0004] Existing production facilities are often pieced together from multiple independent units, with inadequate heat exchange networks between these units. For example, the heat from high-temperature reaction products is usually dissipated directly through cooling water or air coolers, while other materials that require heating need additional steam or electric heating, resulting in high overall system energy consumption, large equipment footprint, increased operating costs, and carbon emissions.

[0005] Traditional designs may require multiple separation towers, such as a separate heavy removal tower, for isomerization products when separating and purifying high-purity 1-butene. This results in a lengthy process path, a large number of devices, and increased initial investment and maintenance costs. Furthermore, the fixed structure of traditional units prevents the increase of the effective concentration of isobutene entering the etherification reactor, making it difficult to improve the purity of MTBE products (typically below 95%), thus weakening product competitiveness. Additionally, the fixed unit structure prevents flexible adjustments to the MTBE and 1-butene yield ratio based on market demand.

[0006] Therefore, there is an urgent need for a new type of device with a more rational structural design, higher system integration, and the ability to achieve material recycling and value-added and energy cascade utilization, in order to solve the above problems. Utility Model Content

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a device for the co-production of high-purity MTBE and 1-butene using a mixture of isobutylene-poor C4 as raw material. By establishing an isomerization enrichment and circulation loop, the low-value n-butene in the etherified C4 is converted into high-value isobutylene, which is then circulated back to the inlet of the etherification reactor via pipeline. This closed-loop design increases the effective concentration of isobutylene in the raw material entering the etherification unit, fundamentally solving the bottleneck of low isobutylene content in the raw material, and enabling the MTBE product purity to consistently reach over 98%.

[0008] This utility model is achieved using the following technical solution: The apparatus for co-producing high-purity MTBE and 1-butene using lean isobutylene mixed C4 as raw material includes an etherification reactor. The etherification reactor is connected to a C4 water washing tower via a catalytic distillation column. The catalytic distillation column is connected to a coiled tube heat exchanger and a 1-butene refining feed heat exchanger via the C4 water washing tower. The coiled tube heat exchanger is connected to a heterogeneous reactor via an electric heater. The heterogeneous reactor is connected to the 1-butene refining feed heat exchanger via the coiled tube heat exchanger. The coiled tube heat exchanger is connected to a compressor buffer tank via the 1-butene refining feed heat exchanger. The compressor is connected to the 1-butene refining feed heat exchanger via the compressor buffer tank. The C4 water washing tower is connected to a n-butane removal tower via the 1-butene refining feed heat exchanger. The n-butane removal tower is connected to an isobutane removal tower via a pipeline.

[0009] The C4 water washing tower is connected to the methanol recovery tower via a pipeline, and the etherification reactor is connected to a methanol feed pipeline. The methanol recovery tower is connected to the methanol feed pipeline via the methanol recovery pipeline.

[0010] The bottom of the isobutane removal tower is connected to a 1-butene discharge pipe, the top of the isobutane removal tower is provided with a C4 component discharge pipe, and the n-butane removal tower is connected to the C4 component discharge pipe through a pipe.

[0011] The heterogeneous reactor is connected to a coiled tube heat exchanger via a pipe, and the coiled tube heat exchanger is connected to a 1-butene refining feed heat exchanger via a pipe.

[0012] The 1-butene refining feed heat exchanger is connected to the compressor via a compressor buffer tank, and the bottom of the compressor buffer tank is provided with a heterogeneous heavy component discharge pipe.

[0013] A compressor buffer tank achieves a dual function. It not only serves as a buffer at the compressor inlet and a gas-liquid separator to protect the compressor, but also has a discharge pipe at its bottom for the isomerized heavy components. By controlling the temperature and pressure inside the tank, the small amount of heavy components generated during isomerization is condensed into liquid and discharged from the bottom. This "one tank, two uses" structure replaces the separate deweighting tower that might be needed in traditional processes, simplifying equipment layout and saving investment.

[0014] The etherification reactor is connected to a C4 feed pipe, and the compressor is connected to the C4 feed pipe through an isobutylene-rich C4 pipe.

[0015] The bottom of the catalytic distillation column is equipped with an MTBE discharge pipe.

[0016] The core structure of this device comprises a closed-loop system consisting of a heterogeneous reactor, a heat exchange and cooling system (winding-tube heat exchanger, 1-butene refining feed heat exchanger), a gas-liquid separation and pressurization system (compressor buffer tank, compressor), and isobutylene-rich C4 pipelines. The pipelines directly connect the pressurized isobutylene-rich material to the feed end of the etherification reactor, achieving material recycling and value enhancement. This specific pipeline connection structure ensures the enrichment of isobutylene and the high purity of MTBE.

[0017] The high-temperature outlet of the heterogeneous reactor is directly connected to the hot-side inlet of the coiled-tube heat exchanger, while its cold-side outlet is connected to the hot-side inlet of the 1-butene refining feed heat exchanger. Simultaneously, the cold side of the coiled-tube heat exchanger is connected to the feed of the heterogeneous unit, and the cold side of the 1-butene refining feed heat exchanger is connected to the feed of the 1-butene refining unit. This series-connected, cascaded heat exchange structure allows for the efficient recovery of a single unit of high-temperature heat energy for preheating two different cold materials, demonstrating a compact and efficient energy integration design.

[0018] Compared with the prior art, the beneficial effects of this utility model are: (1) This device converts low-value n-butene in C4 after etherification into high-value isobutene by setting up an isomer enrichment and circulation loop, and then circulates it back to the inlet of the etherification reactor through a pipeline. This closed-loop structural design increases the effective concentration of isobutene in the raw material entering the etherification unit, fundamentally solving the bottleneck of low isobutene content in the raw material, and enabling the purity of MTBE product to stably reach more than 98%.

[0019] (2) This device cleverly employs a two-stage series heat exchange network. The thermal energy of the high-temperature outlet material from the heterogeneous reactor is utilized in two stages: first, the cold material entering the heterogeneous unit is preheated via a coiled tube heat exchanger, and then the material entering the 1-butene refining unit is further preheated via a 1-butene refining feed heat exchanger. This structure maximizes the recovery of reaction heat, reduces the consumption of external heating steam and the load on cooling utilities, resulting in a significant reduction in energy consumption compared to traditional devices.

[0020] (3) This device designs the compressor buffer tank as a device with gas-liquid separation function, directly removing the heavy components generated by isomerization before the material enters the compressor, eliminating the need to set up a separate heavy component removal tower for the isomer products. In addition, the 1-butene refining unit adopts a series structure of "heavy component removal first and light component removal later", which optimizes the separation sequence. Compared with the traditional separation process, it reduces the equipment size, reduces the consumption of public works, and effectively reduces equipment investment and operating costs.

[0021] (4) A diversion pipe and regulating valve are installed between the outlet of the C4 water washing tower and the inlet of the two downstream units. By adjusting the opening of the valve, the material ratio entering the two units can be changed, thereby flexibly controlling the final relative output of MTBE and 1-butene, enabling the unit to respond quickly to market changes and maximize benefits. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the device for co-producing high-purity MTBE and 1-butene using a mixture of isobutylene and C4 as raw materials according to this invention. In the diagram: 1. Etherification reactor; 2. Catalytic distillation column; 3. C4 water washing column; 4. Methanol recovery column; 5. 1-Butene refining feed heat exchanger; 6. Butane removal column; 7. Isobutane removal column; 8. Tube heat exchanger; 9. Electric heater; 10. Isomerization reactor; 11. Compressor buffer tank; 12. Compressor; 13. C4 feed pipeline; 14. Methanol feed pipeline; 15. Methanol recovery pipeline; 16. Isobutene-rich C4 pipeline; 17. MTBE discharge pipeline; 18. 1-Butene discharge pipeline; 19. C4 component discharge pipeline; 20. Isomerized heavy component discharge pipeline. Detailed Implementation

[0023] To make the objectives and technical solutions of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings.

[0024] Example 1 like Figure 1As shown, the apparatus for co-producing high-purity MTBE and 1-butene using lean isobutylene mixed C4 as feedstock includes an etherification reactor 1. The etherification reactor 1 is connected to a C4 water washing tower 3 via a catalytic distillation column 2. The catalytic distillation column 2 is connected to a coiled tube heat exchanger 8 and a 1-butene refining feed heat exchanger 5 via the C4 water washing tower 3. The coiled tube heat exchanger 8 is connected to a heterogeneous reactor 10 via an electric heater 9. The heterogeneous reactor 10 is connected to the 1-butene refining feed heat exchanger 5 via the coiled tube heat exchanger 8. The coiled tube heat exchanger 8 is connected to a compressor buffer tank 11 via the 1-butene refining feed heat exchanger 5. The compressor 12 is connected to the 1-butene refining feed heat exchanger 5 via the compressor buffer tank 11. The C4 water washing tower 3 is connected to a n-butane removal tower 6 via the 1-butene refining feed heat exchanger 5. The n-butane removal tower 6 is connected to an isobutane removal tower 7 via a pipeline. C4 water washing tower 3 is connected to methanol recovery tower 4 via a pipeline. Etherification reactor 1 is connected to methanol feed pipe 14, and methanol recovery tower 4 is connected to methanol feed pipe 14 via methanol recovery pipe 15. The bottom of isobutane removal tower 7 is connected to 1-butene discharge pipe 18, and the top of isobutane removal tower 7 is equipped with C4 component discharge pipe 19. n-Butane removal tower 6 is connected to C4 component discharge pipe 19 via a pipeline. Isomerization reactor 10 is connected to coiled tube heat exchanger 8 via a pipeline, and coiled tube heat exchanger 8 is connected to 1-butene refining feed heat exchanger 5 via a pipeline. 1-Butene refining feed heat exchanger 5 is connected to compressor 12 via compressor buffer tank 11, and the bottom of compressor buffer tank 11 is equipped with isomer heavy component discharge pipe 20. Etherification reactor 1 is connected to C4 feed pipe 13, and compressor 12 is connected to C4 feed pipe 13 via isobutene-rich C4 pipe 16. The bottom of catalytic distillation tower 2 is equipped with MTBE discharge pipe 17. The high-temperature outlet of the heterogeneous reactor 10 is directly connected to the hot-side inlet of the coiled tube heat exchanger 8, while its cold-side outlet is connected to the hot-side inlet of the 1-butene refining feed heat exchanger 5. Simultaneously, the cold side of the coiled tube heat exchanger 8 is connected to the feed of the heterogeneous unit, and the cold side of the 1-butene refining feed heat exchanger 5 is connected to the feed of the 1-butene refining unit. This series-connected, cascaded heat exchange structure allows for the efficient recovery of a single unit of high-temperature heat energy for preheating two different cold materials.

[0025] The above-mentioned apparatus for co-producing high-purity MTBE and 1-butene using a mixture of C4 and isobutylene as raw materials includes the following steps during operation: (1) Fresh isobutylene-poor mixed C4 feedstock is fed through C4 feed pipe 13 and mixed with recycled material returned from isobutylene-rich C4 pipe 16 and methanol added from methanol feed pipe 14. The mixture enters etherification reactor 1 for etherification reaction. The reaction product enters catalytic distillation column 2, where it continues to react and is separated. High-purity MTBE product is collected from the bottom of the column through MTBE discharge pipe 17. Unreacted C4 and methanol azeotrope enters C4 water washing column 3 from the top of the column and is washed with water to remove methanol. The methanol-water solution at the bottom of the column enters methanol recovery column 4, and the recovered methanol is recycled through methanol recovery pipe 15. (2) The etherified C4 flowing out from the top of C4 water washing column 3 is split into two parts. The first part of the material enters the 1-butene refining unit. It first flows through 1-butene refining feed heat exchanger 5 and is preheated to 55-80°C by hot material from the isomerization unit. Then it enters n-butane removal column 6 to remove n-butane and other heavy components. The top material then enters the isobutane removal tower 7 to remove isobutane and other light components. Finally, the high-purity 1-butene product is collected from the bottom of the isobutane removal tower 7 through the 1-butene discharge pipe 18. (3) The second part of the C4 after etherification enters the butene isomerization unit. It first enters the coiled tube heat exchanger 8 as a cold material, and is preheated to 150-250℃ and vaporized by the high-temperature product from the isomerization reactor 10. Then it is finally heated to the reaction temperature by the electric heater 9 and enters the isomerization reactor 10 equipped with the modified ZSM-35 catalyst to undergo a skeletal isomerization reaction, converting n-butene into isobutene. The high-temperature product after the reaction is cooled in two stages through the coiled tube heat exchanger 8 and the 1-butene refining feed heat exchanger 5, and the heat is recovered and utilized. The cooled material enters the compressor buffer tank 11, where gas-liquid separation is carried out, and the generated heavy components are discharged from the bottom of the isomerized heavy component discharge pipe 20. The gaseous isobutylene-rich C4 enters the compressor 12 and is pressurized to 0.8-1.0 MPaG. Finally, it returns to the inlet of the etherification reactor 1 in step (1) through the isobutylene-rich C4 pipeline 16 to complete the cycle.

Claims

1. An apparatus for co-producing high-purity MTBE and 1-butene using isobutylene-poor mixed C4 as raw material, characterized in that, The reactor includes an etherification reactor (1), which is connected to a C4 water washing tower (3) via a catalytic distillation column (2). The catalytic distillation column (2) is connected to a coiled tube heat exchanger (8) and a 1-butene refining feed heat exchanger (5) via the C4 water washing tower (3). The coiled tube heat exchanger (8) is connected to a heterogeneous reactor (10) via an electric heater (9). The heterogeneous reactor (10) is connected to the 1-butene refining feed via the coiled tube heat exchanger (8). The heat exchanger (5) is connected, the coiled tube heat exchanger (8) is connected to the compressor buffer tank (11) through the 1-butene refining feed heat exchanger (5), the compressor (12) is connected to the 1-butene refining feed heat exchanger (5) through the compressor buffer tank (11), the C4 water washing tower (3) is connected to the n-butane removal tower (6) through the 1-butene refining feed heat exchanger (5), and the n-butane removal tower (6) is connected to the isobutane removal tower (7) through a pipeline.

2. The apparatus for co-producing high-purity MTBE and 1-butene using isobutylene-poor mixed C4 as raw material according to claim 1, characterized in that, The C4 water washing tower (3) is connected to the methanol recovery tower (4) through a pipeline. The etherification reactor (1) is connected to a methanol feed pipeline (14). The methanol recovery tower (4) is connected to the methanol feed pipeline (14) through a methanol recovery pipeline (15).

3. The apparatus for co-producing high-purity MTBE and 1-butene using isobutylene-poor mixed C4 as raw material according to claim 1, characterized in that, The bottom of the isobutane removal tower (7) is connected to a 1-butene discharge pipe (18), and the top of the isobutane removal tower (7) is provided with a C4 component discharge pipe (19). The n-butane removal tower (6) is connected to the C4 component discharge pipe (19) through a pipe.

4. The apparatus for co-producing high-purity MTBE and 1-butene using isobutylene-poor mixed C4 as raw material according to claim 1, characterized in that, The heterogeneous reactor (10) is connected to the coiled tube heat exchanger (8) via a pipe, and the coiled tube heat exchanger (8) is connected to the 1-butene refining feed heat exchanger (5) via a pipe.

5. The apparatus for co-producing high-purity MTBE and 1-butene using isobutylene-poor mixed C4 as raw material according to claim 1, characterized in that, The 1-butene refining feed heat exchanger (5) is connected to the compressor (12) through the compressor buffer tank (11), and the bottom of the compressor buffer tank (11) is provided with a heterogeneous heavy component discharge pipe (20).

6. The apparatus for co-producing high-purity MTBE and 1-butene using isobutylene-poor mixed C4 as raw material according to claim 5, characterized in that, The etherification reactor (1) is connected to a C4 feed pipe (13), and the compressor (12) is connected to the C4 feed pipe (13) through an isobutylene-rich C4 pipe (16).

7. The apparatus for co-producing high-purity MTBE and 1-butene using isobutylene-poor mixed C4 as raw material according to claim 1, characterized in that, The bottom of the catalytic distillation column (2) is provided with an MTBE discharge pipe (17).

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