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Process for separating acetic acid from water by salt-containing extracting, rectifying and separating

A technology for extractive distillation and extractive distillation column, which is applied in the field of salt-added extractive distillation to separate acetic acid and water, and can solve the problems of high energy consumption, low separation efficiency, large number of trays, etc.

Active Publication Date: 2008-11-19
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is that the existing technology has the problems of low separation efficiency, large number of trays and high energy consumption in the process of separating acetic acid and water. method

Method used

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  • Process for separating acetic acid from water by salt-containing extracting, rectifying and separating

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Effect test

Embodiment 1

[0014] The theoretical number of plates of the extractive distillation column is 50 (the number of plates is counted from top to bottom), and the tributylamine liquid mixture (massfraction 5% of potassium thiocyanate) that contains potassium thiocyanate is selected as the salting solvent, Add from the 8th theoretical plate, the flow rate is 8 g / min, the mixture of acetic acid and water is added from the 25th theoretical plate, the mass fraction of water is 70%, the mass fraction of acetic acid is 30%, and the flow rate is 10 g / min . The extractive distillation tower is operated under normal pressure, the reflux ratio at the top of the tower is 0.4, and the temperature at the top of the tower is controlled at 99.5-101.0°C. When analyzing the top product, the mass fraction of water is 99.85%, and the mass fraction of acetic acid is 0.15%. The energy consumption is 4.25 kJ / hour, and the energy consumption of the tower kettle is 7.38 kJ / hour. A small amount of water, acetic acid,...

Embodiment 2

[0016] The theoretical plate number of extractive distillation tower is 50 (the number of plate is counted from top to bottom), selects the tributylamine liquid mixture (massfraction 25% of potassium thiocyanate) that contains potassium thiocyanate as salting solvent, Add from the 8th theoretical plate, the flow rate is 8 g / min, the mixture of acetic acid and water is added from the 25th theoretical plate, the mass fraction of water is 70%, the mass fraction of acetic acid is 30%, and the flow rate is 10 g / min . The extractive distillation tower is operated under normal pressure, the reflux ratio at the top of the tower is 4, and the temperature at the top of the tower is controlled at 99.5-101.0°C. When analyzing the top product, the mass fraction of water is 99.9%, and the mass fraction of acetic acid is 0.1%. The energy consumption is 10.18 kJ / hour, and the energy consumption of the tower kettle is 20.86 kJ / hour. The condition parameter of solvent recovery tower is as embo...

Embodiment 3

[0018] The theoretical plate number of extractive distillation tower is 20 (the number of plate is counted from top to bottom), selects the tributylamine liquid mixture (massfraction 10% of sodium thiocyanate) that contains sodium thiocyanate as salting solvent, Add from the 5th theoretical plate, the flow rate is 22 g / min, the mixture of acetic acid and water is added from the 12th theoretical plate, the mass fraction of water is 70%, the mass fraction of acetic acid is 30%, and the flow rate is 10 g / min . The extractive distillation tower is operated under normal pressure, the reflux ratio at the top of the tower is 3, and the temperature at the top of the tower is controlled at 99.5 to 101.0°C. When analyzing the top product, the mass fraction of water is 99.78%, and the mass fraction of acetic acid is 0.22%. The energy consumption is 8.32 kJ / hour, and the energy consumption of the tower kettle is 18.49 kJ / hour. The extractive distillation column is discharged from a small...

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Abstract

The invention relates to a method for separating acetic acid and water by salt addition, extraction and distillation. The method mainly solves the problems of low separating efficiency, the excess number of column plates and high energy consumption in the separation of the acetic acid and the water. The method adopts the technical proposal comprising the following steps that; an acetic acid aqueous solution enters an extraction and rectification tower and is added with salt, extracted and rectified; the water is extracted in a tower top; and a mixture of the acetic acid, the salt and solvent is obtained in a tower kettle, wherein, the solvent selects at least one of an N-methyl ketopyrrolidine, an N-methylmorpholine, a sulfolane or a tertiary amine organic alkali polar solvent; the salt added in the solvent is selected from at least one of thiocyanate, acetate or nitrate; the mixture of the acetic acid, the salt and the solvent enters to a solvent recovery tower; the distilled liquid in the tower top is the acetic acid with a concentration over 97 percent in mass by percentage; and a saline solvent is obtained in the tower kettle, thereby well solving the problems. The method can be used in industrial application of producing and reclaiming acetic acid.

Description

technical field [0001] The invention relates to a method for separating acetic acid and water by adding salt, extracting and rectifying. Background technique [0002] In the production process of acetic acid, because the relative volatility of acetic acid and water is close to 1, their separation is relatively difficult, and the methods of ordinary rectification and azeotropic rectification are generally used at home and abroad. Ordinary distillation has a simple process flow and easy operation and control, but requires a large number of trays and consumes a lot of energy in the process; azeotropic distillation uses a small number of trays, but the amount of azeotropic agent is large, the configuration is complicated, and the process consumes a lot of energy. Operational control is more complicated. [0003] US5167774 and US4729818 disclose the separation of acetic acid and water by the method of ordinary extraction and rectification. In the US5167774 patent, tetramethylene...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C53/08C07C51/44B01D3/40
Inventor 钟禄平肖剑钟思青顾军民张惠明
Owner CHINA PETROLEUM & CHEM CORP
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