A kind of dilute acetic acid recovery method combining extraction and azeotropic distillation

A technology of azeotropic distillation column and dilute acetic acid, which is applied in chemical recovery, separation/purification of carboxylic acid compounds, etc., can solve the problems of high energy consumption, uneconomical, and increased vapor-liquid phase load of the system, and reduce steam consumption , reduce energy consumption, reduce the effect of content

Inactive Publication Date: 2011-12-07
EAST CHINA UNIV OF SCI & TECH
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Problems solved by technology

If the water concentration is too low, the azeotropic distillation column will need more entrainer, the gas-liquid phase load in the distillation column will increase, and the energy consumption of the system will be high, which is uneconomical

Method used

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  • A kind of dilute acetic acid recovery method combining extraction and azeotropic distillation

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Embodiment

[0025] For the specific flow chart of the embodiment, please refer to figure 1 , the material composition in the present embodiment is based on mass fraction.

[0026] In the mixture stream 1 to be separated, the injection rate of dilute acetic acid is 29225 kg / h, the mass fraction of acetic acid is 0.15, and the mass fraction of water is 0.85. Stream 2, as a part of stream 1, is extracted in the upper part of the extraction tower with a flow rate of 10000kg / h; stream 3 is another part of stream 1, which directly enters the azeotropic distillation tower for heterogeneous azeotropic distillation , the flow rate is 19225kg / h.

[0027] The extraction tower 1 adopts a packed tower, the theoretical plate number of the extraction tower 1 is 30, the selected operating condition is normal temperature 25°C, and the stream temperature can also be selected as 40-50°C, and the operating pressure is generally atmospheric pressure.

[0028] Stream 9 is the extraction agent required for ex...

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Abstract

The invention relates to a method for recovering dilute acetic acid by combining extraction and azeotropic rectification. The method first carries out liquid-liquid extraction on part of the acetic acid-water component to be separated, the extractant is injected into the bottom of the extraction tower, and is extracted by countercurrent contact with dilute acetic acid to obtain the top component (extract phase) comprising acetic acid and the extractant and meet environmental protection requirements. The waste water (raffinate phase) is discharged; then, the extract phase and another part of dilute acetic acid enter the azeotropic rectification tower to carry out azeotropic rectification. Azeotrope of boiling agent and water. The azeotropic agent and water achieve liquid-liquid separation in the phase separator, the organic phase returns to the azeotropic rectification tower as an azeotropic agent and returns to the extraction tower for use as an extraction agent, and the water phase enters the azeotropic agent recovery tower or is discharged. The extractant and entrainer used in the present invention are the mixture of alkyl acetate and corresponding alcohol. The extraction technology reduces the water content entering the azeotropic distillation, thereby reducing the amount of the entrainer and saving the heating steam flow of the azeotropic distillation column, so as to reduce the amount of the azeotrope and the energy consumption of the device.

Description

technical field [0001] The invention provides a method for recovering dilute acetic acid by combining extraction and azeotropic distillation techniques. It belongs to the separation engineering field of chemical engineering, and is especially suitable for the treatment of low-concentration acetic acid wastewater. It is an acetic acid dehydration system combined with an extraction technology and azeotropic distillation technology that takes into account both efficiency and environmental protection. Background technique [0002] Acetic acid is widely used in industry. It can be used as a solvent for oxidation reactions and as an important raw material for organic synthesis industry. During the use of acetic acid, it is often necessary to purify and refine acetic acid, which often involves the separation of acetic acid and aqueous solution. The acetic acid-containing wastewater generated in the production process, although the acetic acid content in the wastewater is low, the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C53/08C07C51/46
CPCY02P20/582
Inventor 李绍军林琳
Owner EAST CHINA UNIV OF SCI & TECH
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