Method for recovering dimethyl formamide

A dimethylformamide, evaporator technology, applied in chemical instruments and methods, carboxylic acid amide separation/purification, water/sludge/sewage treatment, etc. Insufficient rate and other problems, to achieve the effect of reducing the operating temperature of rectification, reducing the rate of re-steaming, and reducing the displacement

Active Publication Date: 2009-09-02
HUALUN LEATHER & PLASTIC SUZHOU
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This type of device uses heat transfer oil or low-pressure steam as a heat source, and the degree of heat energy reuse is not high
Atmospheric pressure rectification is adopted in the device. In the presence of water, when the temperature reaches 120-130°C, DMF is very easy to produce DMF and formic acid, and DMF and formic acid will produce azeotropy. After passing through the four-tower negative pressure deacidification tower The content of DMF in the final formic acid is still very high and must enter the formic acid decomposition tower for partial decomposition, and then return to the rectification tower for repeated rectification through alkali neutralization, which is a great waste of energy
In addition, DMF decomposes dimethylamine, although it can go through the deamination tower and then enter the boi

Method used

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  • Method for recovering dimethyl formamide
  • Method for recovering dimethyl formamide

Examples

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Embodiment 1

[0020] Example 1 As shown in the attached figure, a method for recovering dimethylformamide is carried out in four columns with evaporators operated under negative pressure.

[0021] Wastewater 101 containing about 20% DMF is introduced into a tower 1 with evaporator 1-2 for negative pressure concentration, the operating pressure is -0.095Mpa, the operating temperature is 40°C, and the concentration of DMF can be concentrated to about 40%; At the same time, the steam 2-105 leaving the top of the second tower is introduced into the evaporator 1-1 of the first tower as a heat source to heat the waste water in the first tower 1; the steam 1-105 leaving the top of the first tower is discharged to the outside.

[0022] The waste water containing about 40% DMF drawn from the bottom of the first tower 1 is sent into the evaporator 2-1 of the second tower 2 and heated together with the waste water in the second tower 2, and then enters the second tower 2 for negative pressure concentra...

Embodiment 2

[0026] Example 2 As shown in the attached figure, a method for recovering dimethylformamide is carried out in four columns with evaporators operated under negative pressure. The flow of the entire material is the same as that of Example 1, the difference lies in the operating conditions and the use of low-pressure steam instead of heat transfer oil 104 as a heat source.

[0027] In this embodiment, a tower 1 carries out negative pressure concentration, operating conditions: the pressure is -0-08Mpa, the temperature is 50°C, and the waste water 101 containing about 20% DMF can be concentrated to a concentration of about 45% DMF.

[0028] The second tower 2 carries out negative pressure concentration, operating conditions: the pressure is -0.075Mpa, the temperature is 70°C, the waste water containing about 45% DMF can be concentrated to a concentration of about 65% DMF.

[0029] The three towers 3 carry out negative pressure rectification, operating conditions: the pressure is -...

Embodiment 3

[0032] Example 3 (Comparative Example) The four-tower recovery method of the prior art is used to treat wastewater containing DMF. That is, one tower and two towers are concentrated under negative pressure; three towers are rectified at normal pressure; four towers are deacidified under negative pressure; the flow of materials is basically the same as the above-mentioned examples, the only difference is that the DMF containing high formic acid obtained at the bottom of the four towers needs to pass through alkali After neutralization in water, it goes to three towers for rectification.

[0033] In this embodiment, one tower is concentrated under negative pressure, operating conditions: the pressure is -0.08 ~ -0.085Mpa, the temperature is 50 ~ 60 ° C, the waste water 101 containing about 20% DMF is concentrated to a concentration of about 40% DMF .

[0034] The second tower is concentrated under negative pressure, operating conditions: the pressure is -0.065 ~ -0.07Mpa, the t...

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Abstract

A method for recycling dimethyl formamide relates to a method for recovering dimethyl formamide from waste water by an all-subpressure operation method. The method includes the steps of utilizing conduction oil or low-pressure steam as a heat source, sequentially leading the waste water containing DMF to four subpressure operation towers, and performing subpressure concentration in the first tower and the second tower, subpressure fractionating in the third tower and deacidification in the fourth tower, thereby obtaining finished DMF and methanoic acid. Due to the great decrease of stable operating temperature, the recovery rate of the DMF can reach over 99 percent, and the rate of purity reaches 99.99 percent; the resolution ratio of the DMF and the back evaporation rate of the peracid DMF are obviously reduced, a methanoic acid decomposition tower is cancelled, almost no DMF contains peracid, repeated rectification is not needed, and energy sources are saved by over 10 percent; and meanwhile, the dimethylamine quantity generated by decomposition is little and is completely absorbed by a boiler screen dust collection system without emission.

Description

technical field [0001] The invention relates to a method for reclaiming dimethylformamide from waste water, in particular to a method for reclaiming dimethylformamide from waste water using a full negative pressure operation method. Background technique [0002] Before the present invention was proposed, many domestic synthetic leather factories, acrylic fiber factories, and glove factories used dimethylformamide (abbreviation: DMF, the same below) as a solvent for batching in the production process. In order to reduce production costs, protect the environment, and protect people's health, these production plants have set up recycling devices to recycle DMF for reuse. There are also many equipment manufacturers who have finalized the production of recovery devices and provided them to the production plants. Generally speaking, most of these devices are four-tower processes, that is, the recovered waste water is first vacuum concentrated in the first and second towers to rem...

Claims

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Application Information

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IPC IPC(8): C07C233/03C07C231/24C02F9/10C02F1/04C02F103/36
Inventor 高金岗王俊峰
Owner HUALUN LEATHER & PLASTIC SUZHOU
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