A method for optimizing operation of solvent dehydration system in aromatic acid production process

A technology for system optimization and production process, applied in chemical instruments and methods, separation/purification of carboxylic acid compounds, preparation of organic compounds, etc., can solve problems such as large reflux ratio and high acid consumption, and achieve increased reflux ratio and improved Purity, the effect of increasing energy consumption

Active Publication Date: 2016-06-29
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the process mentioned in the above patents has problems such as high reflux ratio and high acid consumption, and there is no method for optimizing the operation of the solvent dehydration system using aromatic hydrocarbons as entrainers in the reported literature.

Method used

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  • A method for optimizing operation of solvent dehydration system in aromatic acid production process

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Terephthalic acid is produced by catalytic oxidation of p-xylene (PX) under a catalyst at a certain temperature and pressure. During the production process, the acetic acid aqueous solution cooled by the steam at the top of the oxidation reactor enters the upper part of the solvent dehydration tower T1.

[0032] Such as figure 1 As shown, the theoretical plate number of the solvent dehydration tower T1 is 60, the theoretical plate number of the entrainer refining tower T2 is 30, and the theoretical plate number of the methyl acetate recovery tower T3 is 30. The flow rate of the aqueous acetic acid solution entering the solvent dehydration tower is 1000kg / hr, which contains 70wt.% of acetic acid, 29.5wt.% of water, and 0.5wt.% of the quality of methyl acetate. Feed, after the overhead steam 2 is condensed, the condensate 3 enters the phase separator V1, and the concentrated acetic acid 4 extracted from the bottom of the solvent dehydration tower T1 and returned to the ox...

Embodiment 2

[0034] Keep other conditions constant in Example 1, the PX reflux flow rate is 740kg / hr, the reflux flow rate and the total amount ratio of entering the solvent dehydration tower T1 water are 2.5, and the concentrated acetic acid water content of the solvent dehydration tower T1 tower kettle returning to the oxidation unit is 3.5wt.%. , containing PX0.3wt.%, the content of acetic acid in the water phase of the methyl acetate recovery tower T3 is 0.02%, the reflux of the upper water phase of the solvent dehydration tower T1 is 60kg / hr, and the output of the water phase of the methyl acetate recovery tower T3 is It is 230kg / hr, and the reflux rate accounts for 20.1% of the total amount of water phase in the T3 tower kettle of the methyl acetate recovery tower. The extracted methyl acetate content is 98.0%.

Embodiment 3

[0036] Keep other conditions constant in Example 1, the PX reflux flow rate is 590kg / hr, the oil phase reflux flow rate and the total amount ratio of water entering the solvent dehydration tower T1 are 2, and the concentrated acetic acid in the solvent dehydration tower T1 tower kettle returns to the oxidation unit with a water content of 4.0wt .%, containing PX0.2wt.%, the content of acetic acid in the water phase of the tower kettle T3 of the methyl acetate recovery tower is 0.015%, the return flow rate of the water phase in the upper part of the solvent dehydration tower T1 is 75kg / hr, and the water phase of the methyl acetate recovery tower T3 The output is 215kg / hr, and the reflux rate accounts for 25.9% of the total amount of water phase in the tower tank of the methyl acetate recovery tower T3. The content of methyl acetate extracted from the top of the entrainer refining tower T2 is 98.1%. The content of methyl acetate produced at the top of the tower is 98.2%.

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Abstract

The invention discloses a method for optimizing the operation of a solvent dehydration system during the production process of aromatic acid. The aromatic hydrocarbon corresponding to the aromatic acid to be prepared is taken as the azeotropic agent; then the aromatic hydrocarbon is subjected to azeotropic distillation in a solvent dehydration tower; acetic acid can be extracted from the tower bottoms; the condensed liquid from the tower top is separated, the oil phase and water phase go through a azeotropic agent refining tower and a methyl acetate recycling tower to separate methyl acetate and then flow back to the solvent dehydration tower; the top part of the solvent dehydration tower is provided with an oil phase reflux device, the upper part and the lower part of the solvent dehydration tower are both provided with a water phase reflux device; through adjusting the water phase reflux amount of the water phase reflux device arranged on the upper part of the solvent dehydration tower, the oil phase reflux amount can be reduced, thus the energy consumption of the solvent dehydration tower is reduced; the water phase reflux device arranged on the lower part of the solvent dehydration tower can bring the azeotropic agent in the lower part of the solvent dehydration tower to the upper part, and thus the phenomenon that the azeotropic agent is mixed with the condensed acetic acid in the tower kettle of the solvent dehydration tower is avoided, so the content of acetic acid that is returned to the oxidation system is stable.

Description

technical field [0001] The invention relates to a method for separating acetic acid and methyl acetate from an aqueous solution of acetic acid produced by an oxidation unit in the production process of aromatic carboxylic acids, in particular to a method for the production of aromatic carboxylic acids using the same aromatic hydrocarbon as the raw material for the preparation of aromatic acids. A method for optimizing the operation of solvent dehydration systems with boiling agents. Background technique [0002] The solvent dehydration system is an important unit in the production process of aromatic acids, which is used to recover acetic acid and methyl acetate in the vapor phase and part of the liquid phase of the oxidation system. At present, the solvent dehydration processes commonly used in industry include ordinary rectification and azeotropic rectification. Due to the high energy consumption of ordinary distillation, azeotropic distillation has the characteristics of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C53/08C07C51/46C07C69/14C07C67/54
CPCC07C51/46C07C67/54C07C53/08C07C69/14
Inventor 刘宗健汪洋王保正陈韶辉袁浩任珉顾美娟
Owner CHINA PETROLEUM & CHEM CORP
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