MTBE cracking system for producing high-purity isobutene

Abstract

The utility model relates to isobutylene production technical field, specifically a kind of production system of MTBE cracking preparation high-purity isobutylene, including the MTBE refining tower connected in turn, cracking reactor, isobutylene heavy component removal tower, methanol water washing tower, isobutylene light component removal tower, MTBE refining tower connects MTBE raw material input pipeline, the tower bottom of isobutylene light component removal tower is connected high-purity isobutylene output pipeline;The tower bottom of MTBE refining tower is connected MTBE stripping column by tower bottom heavy component pipeline, the top of MTBE stripping column is connected MTBE refining tower by gas phase pipeline.In the utility model, in the bottom of MTBE refining tower, it can greatly reduce the MTBE content in heavy component that one MTBE stripping column is arranged;First heat exchanger is arranged, and the gas phase methanol at the top of methanol recovery column is used as isobutylene heavy component removal tower reboiler heat source, and steam is saved.In addition, methanol refining part is changed into single column from conventional two-column rectification, and the number of equipment is reduced.

Description

Technical Field

[0001] This utility model relates to the field of isobutylene production technology, specifically a production system for producing high-purity isobutylene by MTBE cracking. Background Technology

[0002] High-purity isobutylene is an important chemical raw material with wide applications in many fields. It can be used to produce polyisobutylene, butyl rubber, etc.

[0003] MTBE cracking to produce high-purity isobutylene is one of the most important production processes for high-purity isobutylene. This process uses MTBE as raw material and produces high-purity isobutylene and refined methanol through equipment such as raw material refining tower, cracking reaction, separation and compression, isobutylene de-heavy tower, isobutylene water washing tower, isobutylene de-light tower, methanol recovery tower, methanol de-light tower, and methanol de-heavy tower.

[0004] The above-mentioned conventional process has the following problems: First, in order to ensure that the impurities MSBE in the refined MTBE produced from the side stream are as low as possible and the purity of MTBE is as high as possible, the raw material refining tower will carry 50% to 70% of MTBE in the heavy components at the bottom of the tower. The heavy components are used for blending, resulting in the loss of the effective component MTBE and reducing the utilization rate of the raw material MTBE. How to reduce the MTBE content in the heavy components, improve the MTBE utilization rate, and improve the economic benefits of the unit is one of the problems that need to be solved. Secondly, the latent heat of condensation of the vapor phase methanol at the top of the methanol recovery tower is relatively large. Generally, circulating water is used to directly condense and cool it to 40°C. The latent heat of condensation of the high-temperature vapor phase methanol is not fully utilized, and a large amount of circulating water is consumed. Third, the methanol refining process currently generally uses a two-tower distillation system, namely a methanol light-weight removal tower and a methanol heavy-weight removal tower, which has problems such as long process, many pieces of equipment, large investment, and high energy consumption. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the defects of the prior art and provide a production system for producing high-purity isobutylene by MTBE cracking.

[0006] To solve the above-mentioned technical problems, this utility model provides the following technical solution: A production system for producing high-purity isobutylene by MTBE cracking includes an MTBE refining tower, a cracking reactor, an isobutylene heavy removal tower, a methanol washing tower, and an isobutylene light removal tower connected in sequence. The MTBE refining tower is connected to the MTBE feedstock input pipeline, and the bottom of the isobutylene light removal tower is connected to the high-purity isobutylene output pipeline. The bottom of the MTBE refining tower is connected to the MTBE stripping tower via a bottom reorganization pipeline, and the top of the MTBE stripping tower is connected to the MTBE refining tower via a gas phase pipeline, and is connected to the gas phase space inside the MTBE refining tower.

[0007] In the above structure, the MTBE stripping tower is installed at the bottom of the MTBE refining tower. Due to the height difference, the heavy components at the bottom of the MTBE refining tower can flow by gravity to the top of the MTBE stripping tower without pumping. Through stripping, the MTBE stripping tower can greatly reduce the MTBE content in the heavy components and improve the economic efficiency of the unit.

[0008] The MTBE stripping tower is located below the MTBE refining tower.

[0009] The MTBE stripping tower adopts an integrated tower-tank structure, with the tower mounted on the bottom tank. The tank contains heat exchange tubes as a built-in heater, and low-pressure steam is used to heat the material. This eliminates the need for an external reboiler, saving on-site installation space, reducing equipment investment, and making the stripping operation easier to control. The bottom of the tank is connected to the heavy component output pipeline.

[0010] The methanol washing tower is connected to the methanol recovery tower. The top gaseous methanol pipeline of the methanol recovery tower is connected to the first heat exchanger. After passing through the first heat exchanger, the gaseous methanol pipeline is connected to the top water cooler of the methanol recovery tower. The first heat exchanger is connected to the reboiler material pipeline of the isobutylene de-weighting tower.

[0011] In the above structure, the vaporous methanol at the top of the methanol recovery tower is used as the heat source for the reboiler of the isobutylene de-weighting tower to heat the isobutylene de-weighting tower, thus saving steam. At the same time, the vaporous methanol at the top of the methanol recovery tower is condensed, reducing the circulating water consumption of the methanol recovery tower's top water cooler.

[0012] The bottom crude methanol pipeline of the isobutylene de-weighting tower is connected to the methanol refining tower, the lower part of the methanol refining tower is connected to the side-source refined methanol pipeline, and the side-source refined methanol pipeline is connected to the refined methanol buffer tank.

[0013] The above structure replaces the conventional two-tower distillation of methanol (light and heavy components) with a single-tower methanol refining column using highly efficient structured packing. This reduces the number of equipment units and employs a side-stream extraction scheme. Side-stream extraction ensures that the refined methanol product does not carry either the light components from the top of the column or the heavy components from the bottom, thereby improving the purity of the refined methanol product, simplifying the process, reducing investment, and lowering energy consumption.

[0014] The refined methanol buffer tank is connected to a refined methanol external delivery pump.

[0015] A gaseous MTBE pipeline is installed on one side of the MTBE refining tower. The gaseous MTBE pipeline is connected to the reaction feed heat exchanger, and the bottom output pipeline of the pyrolysis reactor is connected to the reaction feed heat exchanger, so that the two pipelines exchange heat.

[0016] The gas phase MTBE pipeline is also connected to a second heat exchanger, and the bottom output pipeline of the pyrolysis reactor is also connected to a reaction product water cooler, thereby exchanging heat with the external medium.

[0017] The bottom output pipeline of the pyrolysis reactor is connected to the isobutylene deweighting tower after passing through a rich gas compressor.

[0018] The bottom of the methanol washing tower is connected to the middle of the methanol recovery tower via a pipeline, and the bottom of the methanol recovery tower is connected to the upper part of the methanol washing tower via a pipeline.

[0019] The beneficial effects achieved by this utility model are: 1. In this utility model, an MTBE stripping tower is set at the bottom of the MTBE refining tower. The MTBE stripping tower is installed at the bottom of the MTBE refining tower. Due to the height difference, the heavy components at the bottom of the MTBE refining tower can flow by gravity to the top of the MTBE stripping tower without pumping. Through stripping, the MTBE content in the heavy components can be greatly reduced, thereby improving the economic efficiency of the equipment.

[0020] 2. In this utility model, a first heat exchanger is set up to use the vaporized methanol at the top of the methanol recovery tower as the heat source for the reboiler of the isobutylene de-weighting tower to heat the isobutylene de-weighting tower, saving steam. At the same time, the vaporized methanol at the top of the methanol recovery tower is condensed, reducing the amount of circulating water used in the top water cooler of the methanol recovery tower.

[0021] 3. In this utility model, the methanol refining section is changed from the conventional two-tower distillation of methanol light-weight removal tower and methanol heavy-weight removal tower to a single tower, which reduces the number of equipment, simplifies the process, reduces investment, and reduces energy consumption. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of this utility model.

[0023] In the diagram: 1. MTBE refining tower; 2. Cracking reactor; 3. Isobutylene de-heavy component tower; 4. Methanol washing tower; 5. Methanol recovery tower; 6. Isobutylene de-light component tower; 7. MTBE stripping tower; 8. Bottom heavy component pipeline; 9. Second heat exchanger; 10. Reactor feed heat exchanger; 11. Reactor product water cooler; 12. Rich gas compressor; 13. Methanol refining tower; 14. Side-collected refined methanol pipeline; 15. Refined methanol buffer tank; 16. Refined methanol external pump; 17. Bottom crude methanol pipeline; 18. Reboiler material pipeline; 19. First heat exchanger; 20. Gas phase methanol pipeline; 21. Methanol recovery tower top water cooler. Detailed Implementation

[0024] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0025] Example: like Figure 1 As shown, a production system for producing high-purity isobutylene by MTBE cracking includes an MTBE refining tower 1, a cracking reactor 2, an isobutylene de-heavy tower 3, a methanol washing tower 4, and an isobutylene de-light tower 6 connected in sequence. The MTBE refining tower 1 is connected to the MTBE raw material input pipeline, and the bottom of the isobutylene de-light tower 6 is connected to the high-purity isobutylene output pipeline. The bottom of the MTBE refining tower 1 is connected to the MTBE stripping tower 7 via a bottom reorganization branch pipeline 8, and the top of the MTBE stripping tower 7 is connected to the MTBE refining tower 1 via a gas phase pipeline, and is connected to the gas phase space inside the MTBE refining tower 1.

[0026] In the above structure, the MTBE stripping tower 7 is installed at the bottom of the MTBE refining tower 1. Due to the height difference, the heavy components at the bottom of the MTBE refining tower 1 can flow by gravity to the top of the MTBE stripping tower 7 without pumping. Through stripping, the MTBE stripping tower 7 can greatly reduce the MTBE content in the heavy components and improve the economic efficiency of the unit.

[0027] The MTBE stripping tower 7 is located below the MTBE refining tower 1.

[0028] The MTBE stripping tower 7 adopts an integrated tower-tank structure, with the tower mounted on the bottom tank. The tank contains heat exchange tubes as a built-in heater, and low-pressure steam is used to heat the material. This eliminates the need for an external reboiler, saving on-site installation space, reducing equipment investment, and making the stripping operation easier to control. The bottom of the tank is connected to the heavy component output pipeline.

[0029] The methanol washing tower 4 is connected to the methanol recovery tower 5. The top gaseous methanol pipeline 20 of the methanol recovery tower 5 is connected to the first heat exchanger 19. After passing through the first heat exchanger 19, the gaseous methanol pipeline 20 is connected to the top water cooler 21 of the methanol recovery tower. The first heat exchanger 19 is connected to the reboiler material pipeline 18 of the isobutylene de-weighting tower 3.

[0030] In the above structure, the vaporous methanol at the top of methanol recovery tower 5 is used as the heat source for the reboiler of isobutylene de-weighting tower 3 to heat the isobutylene de-weighting tower 3, saving steam. At the same time, the vaporous methanol at the top of methanol recovery tower 5 is condensed, reducing the circulating water consumption of the methanol recovery tower top water cooler 21.

[0031] The bottom crude methanol pipeline 17 of the isobutylene de-weighting tower 3 is connected to the methanol refining tower 13, the lower part of the methanol refining tower 13 is connected to the side-source refined methanol pipeline 14, and the side-source refined methanol pipeline 14 is connected to the refined methanol buffer tank 15.

[0032] The above structure replaces the conventional two-tower distillation of methanol light component removal and methanol heavy component removal with a single-tower methanol refining tower 13 with high-efficiency structured packing, reducing the number of equipment and adopting a side-stream extraction scheme. Side-stream extraction can ensure that the refined methanol product does not carry the light components from the top of the tower or the heavy components from the bottom of the tower, which can improve the purity of the refined methanol product, simplify the process, reduce investment, and reduce energy consumption.

[0033] The refined methanol buffer tank 15 is connected to the refined methanol external pump 16.

[0034] A gaseous MTBE pipeline is installed on one side of the MTBE refining tower 1. The gaseous MTBE pipeline is connected to the reaction feed heat exchanger 10. The bottom output pipeline of the cracking reactor 2 is connected to the reaction feed heat exchanger 10, so that the two pipelines exchange heat.

[0035] The gas phase MTBE pipeline is also connected to the second heat exchanger 9, and the bottom output pipeline of the pyrolysis reactor 2 is also connected to the reaction product water cooler 11, thereby exchanging heat with the external medium.

[0036] The bottom output pipeline of the pyrolysis reactor 2 is connected to the isobutylene deweighting tower 3 after passing through the rich gas compressor 12.

[0037] The bottom of the methanol washing tower 4 is connected to the middle of the methanol recovery tower 5 via a pipeline, and the bottom of the methanol recovery tower 5 is connected to the upper part of the methanol washing tower 4 via a pipeline.

[0038] In practical implementation, taking the production of high-purity isobutylene from 60,000 tons / year of MTBE cracking as an example, the effects of this technical solution after implementation are as follows: (1) The purity of high-purity isobutylene products increased from 99.5% to 99.9%, and the product quality improved.

[0039] (2) Adding a first heat exchanger 19, with an investment of RMB 230,000, can save 1.4t / h of heating steam for isobutylene de-weighting tower 3, and at the same time save 87t / h of circulating water for methanol recovery tower top water cooler 21.

[0040] (3) The methanol refining section was changed from the conventional two-tower distillation of methanol light and heavy removal towers to a methanol refining tower 13 with high-efficiency structured packing and a side-stream extraction methanol refining scheme. The number of equipment was reduced from 14 to 8. The investment was reduced from 4 million to 2.6 million, a decrease of 35%. Steam consumption was reduced from 3.5 t / h to 2.6 t / h, a decrease of 25.7%.

[0041] As can be seen from the data in the examples, this production system can significantly improve the quality of high-purity isobutylene products, reduce steam and circulating water consumption, and reduce equipment investment. The effect is remarkable and effectively solves the problems existing in the prior art.

Claims

1. A production system for producing high-purity isobutylene by MTBE cracking, characterized in that, The system includes an MTBE refining tower (1), a cracking reactor (2), an isobutylene de-heavy tower (3), a methanol washing tower (4), and an isobutylene de-light tower (6) connected in sequence. The MTBE refining tower (1) is connected to the MTBE feedstock input pipeline, and the bottom of the isobutylene de-light tower (6) is connected to the high-purity isobutylene output pipeline. The bottom of the MTBE refining tower (1) is connected to the MTBE stripping tower (7) via a bottom reorganization branch line (8), and the top of the MTBE stripping tower (7) is connected to the MTBE refining tower (1) via a gas phase line and connected to the gas phase space inside the MTBE refining tower (1).

2. The production system for producing high-purity isobutylene by MTBE cracking according to claim 1, characterized in that, The MTBE stripping tower (7) is located below the MTBE refining tower (1).

3. The production system for producing high-purity isobutylene by MTBE cracking according to claim 1, characterized in that, The MTBE stripping tower (7) adopts an integrated tower-tank structure. The tower is installed on the bottom tank, and a heat exchange tube is installed inside the tank as a built-in heater. Low-pressure steam is used to heat the material.

4. The production system for producing high-purity isobutylene by MTBE cracking according to claim 1, characterized in that, The methanol washing tower (4) is connected to the methanol recovery tower (5). The top gaseous methanol pipeline (20) of the methanol recovery tower (5) is connected to the first heat exchanger (19). After passing through the first heat exchanger (19), the gaseous methanol pipeline (20) is connected to the top water cooler (21) of the methanol recovery tower. The first heat exchanger (19) is connected to the reboiler material pipeline (18) of the isobutylene de-weighting tower (3).

5. The production system for producing high-purity isobutylene by MTBE cracking according to claim 1, characterized in that, The bottom crude methanol pipeline (17) of the isobutylene de-weighting tower (3) is connected to the methanol refining tower (13), the lower part of the methanol refining tower (13) is connected to the side-source refined methanol pipeline (14), and the side-source refined methanol pipeline (14) is connected to the refined methanol buffer tank (15).

6. The production system for producing high-purity isobutylene by MTBE cracking according to claim 5, characterized in that, The refined methanol buffer tank (15) is connected to the refined methanol external pump (16).

7. The production system for producing high-purity isobutylene by MTBE cracking according to claim 1, characterized in that, A gas phase MTBE pipeline is installed on one side of the MTBE refining tower (1), and the gas phase MTBE pipeline is connected to the reaction feed heat exchanger (10). The bottom output pipeline of the cracking reactor (2) is connected to the reaction feed heat exchanger (10).

8. The production system for producing high-purity isobutylene by MTBE cracking according to claim 7, characterized in that, The gas phase MTBE pipeline is also connected to the second heat exchanger (9), and the bottom output pipeline of the pyrolysis reactor (2) is also connected to the reaction product water cooler (11).

9. The production system for producing high-purity isobutylene by MTBE cracking according to claim 7, characterized in that, The bottom output pipeline of the pyrolysis reactor (2) is connected to the isobutylene deweighting tower (3) after passing through the rich gas compressor (12).

10. The production system for producing high-purity isobutylene by MTBE cracking according to claim 4, characterized in that, The bottom of the methanol washing tower (4) is connected to the middle of the methanol recovery tower (5) via a pipeline, and the bottom of the methanol recovery tower (5) is connected to the upper part of the methanol washing tower (4) via a pipeline.

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