Method and device for removing light components in trioxymethylene

A technology of paraformaldehyde and light components, applied in the fields of fractionation, organic chemistry, etc., can solve the problems of easy decomposition of paraformaldehyde, high energy consumption of the tower, and low operation flexibility of removing light components, so as to avoid a large amount of decomposition , Lower tower bottom temperature and higher product purity

Active Publication Date: 2013-12-18
XINGTAI RISUN COAL CHEM IND
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  • Abstract
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  • Application Information

AI Technical Summary

Problems solved by technology

However, in the production process of this method, the operation flexibility of removing light components in the light removal process is extremely small, and the content of trace methanol, formaldehyde, formic acid and water in the paraformaldehyde solution in the tower kettle is relatively high, and the general paraformaldehyde content is 99.90% %~99.96%, methanol content is 50~180ppm, formaldehyde content is 60~210ppm, formic acid content is 40~120ppm, water content is 80~220ppm, the operating temperature at the bottom of the tower is 124~128℃, and the reflux ratio is 3~5. The energy consumption of the tower is high, and the paraformaldehyde with a long residence time at high temperature is easy to decompose

Method used

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  • Method and device for removing light components in trioxymethylene

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Comparison scheme
Effect test

Embodiment 1

[0019] (1) Send the extracted mixture of paraformaldehyde, benzene, a small amount of water and organic matter into the light removal tower, and carry out the removal under the conditions of tower bottom temperature 120°C, tower top temperature 79°C, reflux ratio 2, and pressure 2Kpa. Light, the top gas of the light removal tower returns to the extraction process after being condensed and cooled.

[0020] (2) The mixture of paraformaldehyde and trace amounts of water, methanol, formaldehyde, formic acid, etc. at the bottom of the tower after light removal is sent to the stripping tower. The stripping tower uses nitrogen as the stripping medium. The stripping is carried out at a temperature of 115°C and a pressure of 1Kpa.

[0021] After detection and analysis, the content of paraformaldehyde in the bottom of the stripping tower is 99.99%, the content of methanol is 27ppm, the content of formaldehyde is 28ppm, the content of formic acid is 14ppm, and the content of water is 22p...

Embodiment 2

[0023] (1) Send the extracted mixture of paraformaldehyde, benzene, a small amount of water and organic matter into the light removal tower, and carry out the removal under the conditions of tower bottom temperature 122°C, tower top temperature 79°C, reflux ratio 3, and pressure 5Kpa. Light, the top gas of the light removal tower returns to the extraction process after being condensed and cooled.

[0024] (2) The mixture of paraformaldehyde and trace amounts of water, methanol, formaldehyde, formic acid, etc. at the bottom of the tower after light removal is sent to the stripping tower. The stripping tower uses nitrogen as the stripping medium. The stripping is carried out under the conditions of temperature 116°C and pressure 5Kpa.

[0025] After detection and analysis, the content of paraformaldehyde in the bottom of the stripping tower is 99.97%, the content of methanol is 40ppm, the content of formaldehyde is 35ppm, the content of formic acid is 25ppm, and the content of w...

Embodiment 3

[0027] (1) Send the extracted mixture of paraformaldehyde, benzene, a small amount of water and organic matter into the light removal tower, and carry out the process under the conditions of tower bottom temperature 118°C, tower top temperature 78°C, reflux ratio 1, and pressure 0.1Kpa. Light removal, the top gas of the light removal tower returns to the extraction process after being condensed and cooled.

[0028] (2) The mixture of paraformaldehyde and trace amounts of water, methanol, formaldehyde, formic acid, etc. at the bottom of the tower after light removal is sent to the stripping tower. The stripping tower uses nitrogen as the stripping medium. The stripping is carried out under the conditions of temperature 114°C and pressure 0.1Kpa.

[0029] After detection and analysis, the content of paraformaldehyde in the bottom of the stripping tower is 99.95%, the content of methanol is 115ppm, the content of formaldehyde is 128ppm, the content of formic acid is 56ppm, and th...

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Abstract

The invention discloses a method and a device for removing light components in trioxymethylene, which belong to the technical field of purification of trioxymethylene. The method includes the following steps of firstly, feeding extracted trioxymethylene, benzene and small amount of mixture of water and organic matter into a light component removing tower to remove light components, returning to extraction process after gas on the top of the light component removing tower is condensed and cooled; and secondly; feeding trioxymethylene at the bottom of the light component removing tower and small amount of mixture of water, methyl alcohol, formaldehyde, formic acid and the like to be stripped in a stripper. By adding the stripper, temperature at the bottom of the light component removing tower and backflow ratio can be reduced by the additional stripping process, energy consumption is reduced greatly, trioxymethylene can be prevented from being decomposed greatly, and purity of trioxymethylene can be improved effectively.

Description

technical field [0001] The invention relates to the technical field of paraformaldehyde purification, in particular to a method and a device for removing light components from paraformaldehyde. Background technique [0002] Trioxane is an important raw material for the production of engineering plastic polyoxymethylene. In the production process, the purity of paraformaldehyde is required to be ≥99.98%, water ≤100ppm, and other impurities (including methanol, formaldehyde, formic acid, heavy components, etc.) ≤100ppm. After synthesis and concentration, the concentration of paraformaldehyde reaches 30% to 50%. Since the mixture of paraformaldehyde, formaldehyde and water can form a ternary azeotropic component of paraformaldehyde-formaldehyde-water, it is difficult to purify the three components by simple distillation techniques. There are currently two main methods for subsequent separation and purification of polyoxymethylene, namely freeze crystallization and extraction s...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D323/06B01D3/14
Inventor 牛磊范娟娟刘剡薛永行王灵清杨洪庆牛建波王成胡方元韩金乐
Owner XINGTAI RISUN COAL CHEM IND
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