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Continuous production method for separating acetic acid from water by azeotropic distillation

A technology of azeotropic distillation and production method, which is applied in the field of continuous production of acetic acid and water separated by azeotropic distillation, which can solve the problems of large circulation loss of azeotropic agent and failure of automatic control, etc., and achieve good technical effect and stable operation Effect

Active Publication Date: 2013-07-24
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The technical problem to be solved by the present invention is that the control mode of the solvent dehydration tower in the prior art has limitations, and it is impossible to realize automatic control when the feed flow rate changes greatly, and the circulation loss of the entrainer is large as the feed load changes. To provide a new continuous production method for the separation of acetic acid and water by azeotropic distillation

Method used

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  • Continuous production method for separating acetic acid from water by azeotropic distillation
  • Continuous production method for separating acetic acid from water by azeotropic distillation

Examples

Experimental program
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Effect test

Embodiment 1

[0033] use figure 1 process shown. In terms of weight percentage, the feed composition is 61.5% of water, 37.8% of acetic acid, and the rest is methyl acetate and p-xylene. The rectification column has 60 plates (equivalent to 36 theoretical plates), the feed position is 36# plate, and the sensitive plate position is 27# plate. The feed rate is 100% of the normal load. The reflux flow of the side line is 3758 kg / h, the reflux flow of the oil phase at the top of the tower is 125000 kg / h, and the reflux flow of the water phase at the top of the tower is 7000 kg / h. The logistics situation and control effect are shown in Table 1.

[0034] The internal parts of the rectification column adopt sieve plate. According to the conventional design, the plate spacing is 550 mm, the tower diameter is 5200 mm, the opening ratio is 10%, and the double flow type, the lower limit of the vapor phase flow rate is 68% of the normal vapor phase lower limit.

[0035] The reflux rate and the fee...

Embodiment 2

[0037] use figure 1 process shown. In terms of weight percentage, the feed composition is 61.5% of water, 37.8% of acetic acid, and the rest is methyl acetate and p-xylene. There are 60 plates in the rectification column, the feeding position is 36# plate, and the sensitive plate position is 27# plate. The feed rate was 110% of normal load.

[0038] The feed flow rate of the rectification tower is uniformly cascade controlled through the liquid level controller 2 of the acetic acid intermediate tank 1 . The return flow of the side line is controlled according to the temperature of the sensitive plate, R OB = 4133.8. The return flow of the oil phase at the top of the tower is controlled by feedforward, and the total return flow of the oil phase R O f F ×A W × K = 71582.2 × 61.5% × 3.19 = 141413.8, the return flow rate of the oil phase at the top of the tower is R OA =R O -R OB =141413.8-4133.8=137500. The reflux flow of the water phase at the top of the tower is cont...

Embodiment 3

[0042] use figure 1 process shown. In terms of weight percentage, the feed composition is 61.5% of water, 37.8% of acetic acid, and the rest are entrainer methyl acetate and a small amount of p-xylene. There are 60 plates in the rectification column, the feeding position is 36# plate, and the sensitive plate position is 27# plate. The feed rate was 70% of the normal load.

[0043] The feed flow rate of the rectification tower is uniformly cascade controlled through the liquid level controller 2 of the acetic acid intermediate tank 1 . The return flow of the side line is controlled according to the temperature of the sensitive plate, R OB =2630. The return flow of the oil phase at the top of the tower is controlled according to the flow rate of 70% of the normal load, and the return flow of the oil phase at the top of the tower is R OA =87500. Return flow rate of water phase at the top of the tower R W =R O ×K2=90130.6×0.054=4900.

[0044] The design of rectifying colu...

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Abstract

The invention relates to a continuous production method for separating an acetic acid from water by azeotropic distillation, which mainly solves the problems of a solvent dehydration tower in the prior art, such as limitations to control methods, incapability of realizing automatic control when a feeding flow is significantly changed, and a large amount of entrainer circulation loss produced withthe change of a feeding load. In the method, uniform cascade control is performed on the liquid level of the feeding flow, passing through an acetic acid intermediate tank, of a rectifying tower; when the feeding flow of the rectifying tower is larger than the lower limit of the elastic operating range of the tower, feeding flow forward control is performed on the refluxing of water and oil phases at the top of the tower; and when the feeding flow reaches or is smaller than the lower limit of the elastic operating range, constant-flow control is performed on the refluxing of the oil phase at the top of the tower, and feeding flow proportional control is performed on the refluxing of the water phase. In the technical scheme, the problems are better solved; and the continuous production method can be applied to the industrial production of separating the acetic acid from the water by the azeotropic distillation.

Description

technical field [0001] The invention relates to a continuous production method for separating acetic acid and water by azeotropic distillation. Background technique [0002] The industrial production of terephthalic acid (Terephthalic Acid, TA) generally adopts the liquid-phase oxidation technology of p-xylene, that is, acetic acid as a solvent is introduced into the oxidation reactor, and cobalt acetate, manganese acetate and Hydrogen bromide, feed raw material p-xylene and air to carry out oxidation reaction at the same time. Since a large amount of heat of reaction is generated during the oxidation reaction, the solvent in the oxidation reactor, water generated during the reaction and some reaction by-products will be evaporated in large quantities. The evaporated steam is condensed and cooled in a series of heat exchangers connected in series, and part of the obtained condensate is sent back to the oxidation reactor, and the rest is sent to the solvent dehydration tower...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C53/08C07C51/46
Inventor 陈迎何勤伟李真泽
Owner CHINA PETROLEUM & CHEM CORP
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