CN216472988U - High-purity MTBE preparation system capable of efficiently removing isobutene - Google Patents

Abstract

The application provides a high-purity MTBE preparation system of high-efficient desorption isobutene, this preparation system including etherification prereactor, catalytic rectification tower and in the etherification prereactor and catalytic rectification tower between the rectification separator who obtains the MTBE goods that concatenates. The technical scheme realizes the high-efficiency removal of isobutene and simultaneously obtains the MTBE product with high purity and quality, and has the practical technical advantages of shortening the process flow, simplifying the system composition and having industrial economy.

Description

High-purity MTBE preparation system capable of efficiently removing isobutene

Technical Field

The patent application relates to the field of petrochemical industry, in particular to a process unit system for removing isobutene in mixed carbon four by using a process method for preparing MTBE.

Background

The popularization and implementation of the embodiment about expanding the production of biofuel ethanol and popularizing and using the ethanol gasoline for vehicles means that MTBE cannot be used as a gasoline additive component and faces a forbidden situation. However, besides the application as gasoline additive component, MTBE is an important chemical raw material, but when used as a chemical raw material, the purity requirement of MTBE is high, and the purity of MTBE as a gasoline additive component cannot meet the application requirement of the chemical raw material. The reason is that by-product impurities such as MSBE and the like can be generated in the preparation of MTBE by etherification, and because the boiling points of the MSBE impurities and the MTBE are very close to each other and are only 3.8 ℃, great process difficulty is brought to the purification of the MTBE, and the energy consumption is high.

Another technical significance of MTBE production exists in that it is a process that removes isobutylene from mixed C four cuts with minimal loss of butene-1 components. Butene-1 is an important basic chemical raw material, is mainly used for synthesizing sec-butyl alcohol, dehydrogenating to prepare butadiene and the like, and industrial carbon four is a main resource for providing butene-1. The industrial C-IV fraction mainly contains cis-2-butene, trans-2-butene, isobutene, normal butane, isobutane and other components besides butene-1, and the butene-1 and the isobutene have extremely close boiling points, so that the butene-1 and the isobutene cannot be separated by adopting a conventional rectification process, and the synthesis of MTBE becomes a practical and feasible technical process for separating the isobutene fraction from C-IV and avoiding the loss of the butene-1.

However, the prior MTBE preparation process method has the following technical problems: the method aims at pursuing the quality of high-purity MTBE, the conversion rate of isobutene is low, and the index requirement on isobutene content when industrial carbon four is supplied as a butene raw material cannot be met; and with the technical goal of deeply removing isobutene in industrial carbon IV, the purity of the prepared MTBE can hardly reach the purity index of the chemical raw material. The technical means of the existing MTBE preparation process cannot give consideration to the technical requirements of two aspects, and even if the technical requirements of two aspects are given consideration to the technical conditions, the process is too complex, the system flow is long, the equipment components are many, and the operation energy consumption is high.

Disclosure of Invention

The invention aims to apply an MTBE preparation means, shorten the process flow, simplify the system composition, realize the efficient removal of isobutene from industrial mixed C4 fraction and obtain an MTBE product with high purity and quality, and provide a high-purity MTBE preparation system capable of efficiently removing isobutene.

The technical scheme of the high-purity MTBE preparation system for efficiently removing isobutene provided by the patent application comprises the following main technical contents: a high-purity MTBE preparation system capable of effectively removing isobutene comprises an etherification pre-reactor for preparing MTBE and a catalytic rectifying tower, and is characterized in that a rectifying separator for separating MTBE products from product material flow of the etherification pre-reactor is connected in series between the etherification pre-reactor and the catalytic rectifying tower, and intermediate product vapor-phase material flow separated by the rectifying separator is connected into a feeding pipe of the catalytic rectifying tower.

In a preferred embodiment of the above overall solution, the pre-reactor is formed by connecting one or more reactors in series.

In one preferable embodiment of the above-mentioned overall technical solution, the rectifying separator is a plate-type rectifying tower or a packed rectifying tower having a stripping section and a rectifying section disposed therein.

In a preferable aspect of the above overall technical solution, the etherification pre-reactor is a fixed bed reactor, a tubular reactor or an expanded bed reactor, and the hot spot temperature control mode is external circulation heat extraction or tubular isothermal reactor.

In one preferred embodiment of the above whole technical scheme, one branch of the catalytic distillation tower top condensate flows back to the top of the distillation separator.

In a preferable top of the above-mentioned whole technical solution, the bottom of the rectifying separator is connected with a reboiler external pipeline.

According to the technical scheme of the high-purity MTBE preparation system for efficiently removing isobutene, MTBE is separated from a product mixture in a rectifying separator before an etherified product enters catalytic rectification, the catalytic rectification process that side reactions such as MSBE and isobutene dimerization are easy to occur is avoided, and the influence of side reaction impurities on the quality of the separated MTBE is avoided, so that the purity of the separated MTBE is ensured, high-quality MTBE products with the purity higher than 99% are obtained, and the technical index requirements of the MTBE products as chemical raw materials are met; the separated intermediate product material flow is sent into a catalytic distillation tower again, the deep reaction is carried out on the material flow containing unreacted isobutene and methanol under the action of a catalyst, the MTBE generated by the catalytic distillation tower along with the reaction is separated, the etherification reaction balance in the catalytic distillation tower is broken, the material flow continuously and deeply reacts in the positive direction of etherification, the comprehensive reaction is carried out, the high conversion rate of isobutene is realized, the content of isobutene in the residual carbon four is less than or equal to 100ppm, and the technical index requirement of the material flow as a butene raw material on the content of isobutene is met. The technical scheme also has the following technical advantages: firstly, the material separated by MTBE in the rectifying and separating part is a vapor phase, and the vapor phase material flow directly enters the catalytic rectifying tower without condensation treatment, so that the secondary vaporization process of the catalytic distilling tower on the feeding material is omitted, and the energy consumption is greatly saved; the rectification separator and the catalytic distillation tower actually share a set of condensation reflux composition, and the condensation reflux composition comprises a condenser, a reflux tank and a reflux pump, so that the equipment composition is simplified, the consumption of circulating cooling water is saved, and the energy consumption is further reduced; thirdly, the technical scheme has wide application types of the mixed C-C raw materials; in sum, the technical scheme has the practical technical advantage of industrial economy.

Drawings

FIG. 1 is a schematic diagram of a production system of the present patent application.

Detailed Description

The high-purity MTBE process method for efficiently removing isobutene uses industrial mixed C4 and methanol as raw materials, improves the isobutene conversion rate through an etherification pre-reactor and a catalytic rectification tower, and simultaneously prepares the high-purity MTBE, so that the obtained MTBE meets the high technical index requirement of the MTBE as a chemical raw material on the purity, and the residual carbon C meets the technical index requirement of the MTBE as a butylene raw material on the low isobutene content.

The basic preparation system based on the process method comprises an etherification pre-reactor 2 for preparing MTBE by industrial mixed carbon tetra-etherification and a catalytic rectification tower 4. And carrying out isobutene etherification catalytic reaction on industrial mixed C4 and methanol in an etherification pre-reactor 2 under the action of an acid catalyst. The etherification pre-reactor 2 can be one of a fixed bed reactor, a tubular reactor or an expanded bed reactor, and can also be formed by connecting one reactor or a plurality of reactors in series or in parallel. The control mode of the hot spot temperature of the etherification pre-reactor 2 is an external circulation heat taking mode or a tubular constant temperature reactor and the like. The methanol feed stream 103 and the carbon four feed stream 101 enter the etherification reactor 2 from the top thereof, and the product stream 104 is led out from the bottom of the etherification reactor 2. Wherein, the catalyst can be ion exchange resin catalyst, molecular sieve catalyst, etc., and is packed in bulk with regular packing or particles.

The industrial mixed C-C raw material is wide in application range, can be cracking C-C, the isobutene content of the cracking C-C is 35-46 wt% generally, or catalytic cracking C-C, the isobutene content of the cracking C-C is 9-25 wt% generally, and can also be etherified C-C, the isobutene content of the cracking C-C is 2-5 wt% generally, or a mixture of at least two of the C-C.

In order to avoid the influence of heavy components in the raw materials, such as carbon five, MTBE, MSBE, TBA, sulfide and the like on the separation of the rectification separation part to obtain the purity of the MTBE, the heavy components of the raw materials 100 can be removed from a de-weighting tower 1, and the de-weighted mixed carbon four raw material flow 101 and a methanol raw material flow 103 enter an etherification pre-reactor 2 for etherification reaction. The alcohol-olefin ratio is preferably controlled to 1.0-5.0. In the implementation, in order to control the occurrence of side reactions, the impurity content of byproducts such as MSTE, TBA, dimers and the like in the etherification reaction product material flow 104 is reduced, the high purity of the MTBE product obtained in the rectification separation part is ensured, the reaction temperature is preferably controlled to be 35-70 ℃, the most preferably 40-60 ℃, and the reaction pressure is preferably 0.6-1.0 MPa; the hot spot temperature control mode of the reactor is an external circulation heat-taking reactor or a tubular constant temperature reactor.

The catalytic distillation tower 4 is a conventional catalytic distillation device tower, and catalysts such as ion exchange resin catalysts, molecular sieve catalysts and the like are filled in the reaction section in a regular packing mode or a particle bulk packing mode. After the catalytic distillation column 4 is connected to the etherification pre-reactor 2, the unreacted isobutene in the product stream 104 is subjected to a deep reaction and product separation. The top of the tower is a residual carbon four-stream 108 containing methanol, after condensation and cooling, one branch is taken as a reflux stream 109 at the top of the tower, and the other branch is sent to the downstream, such as a methanol recovery part, and is subjected to methanol recovery and recycling through an extraction tower 5 and a rectification recovery tower 6 of the methanol recovery part. The etherification reactor, the catalytic distillation column and the methanol recovery unit are not substantially related to the innovative technical means of the present application, and thus are not described in detail.

In the preparation system, a rectification separator 3 is connected in series between an etherification pre-reactor 2 and a catalytic rectification tower 4 and is used for separating MTBE from an etherification reaction product material flow 104, and the obtained MTBE material flow 105 has high purity and the content is more than or equal to 99 percent; the required operation heat is provided for the rectifying separator, and the tower bottom of the rectifying separator is connected with a reboiler external pipeline 9.

The rectifying separator 3 is a plate-type rectifying tower or a packed rectifying tower internally provided with a stripping section and a rectifying section; the separated vapor phase material flow 106 of the rectifying separator 3 is directly connected into a stripping section feeding pipe of the catalytic rectifying tower 4, the unreacted isobutene in the material flow is continuously subjected to deep reaction and product separation in the catalytic rectifying tower 4, and the material flow 107 with low content of MTBE containing byproducts is output from the tower bottom.

In the preparation system, the operating pressure of the rectifying separator 3 is lower than that of the etherification pre-reactor 2, and is not lower than the reaction operating pressure of the catalytic rectifying tower 4, and the optimal pressure is 0.4-0.8 MPa.

After condensation and cooling, the residual carbon four stream 108 containing methanol at the top of the catalytic rectifying tower 4 is taken as a reflux stream 109 at the top of the tower, and one branch of condensate is taken as a reflux stream 110 at the top of the rectifying separator 3, the reflux stream 110 at the top of the rectifying separator 3 can be connected with the carbon four after the downstream methanol extraction, and the reflux amount of the reflux stream 110 is 0.1-0.5 times of the residual carbon four stream 108 containing methanol.

Claims (10)

1. A high-purity MTBE preparation system capable of efficiently removing isobutene comprises an etherification pre-reactor (2) for preparing MTBE and a catalytic rectifying tower (4), and is characterized in that a rectifying separator (3) for separating MTBE products from a product material flow of the etherification pre-reactor is connected in series between the etherification pre-reactor (2) and the catalytic rectifying tower (4), and an intermediate product material flow (106) separated by the rectifying separator (3) is connected to a feeding pipe of the catalytic rectifying tower (4).

2. The system according to claim 1, characterized in that the pre-reactor (2) is formed by a reactor or a plurality of reactors connected in series.

3. The production system according to claim 1, wherein the rectifying separator (3) is a plate-type rectifying column or a packed rectifying column having a stripping section and a rectifying section inside.

4. The production system according to claim 1 or 3, characterized in that the etherification pre-reactor (2) is a fixed bed reactor, a tubular reactor or an expanded bed reactor.

5. The production system according to claim 4, characterized in that the etherification pre-reactor (2) employs an external circulation heat-removal reactor or a shell-and-tube isothermal reactor.

6. The system according to claim 1, wherein a branch of the overhead condensate stream of the catalytic distillation column (4) is refluxed to the top of the distillation separator (3).

7. The production system according to claim 1, wherein the production system is further provided with a downstream component, and the downstream component is a methanol recovery section.

8. A production system according to claim 7, wherein the rectification separator (3) is connected with a reflux at the top with a methanol extracted C4 from a downstream methanol recovery section.

9. The preparation system according to claim 1, wherein a reboiler external pipeline (9) is connected to the bottom of the rectification separator (3).

10. The preparation system according to claim 1, characterized in that a de-weighting tower (1) is arranged in the system, and the de-weighted mixed carbon four material flow (101) and the methanol material flow (103) are connected to enter the etherification pre-reactor (2).

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