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A device and method for efficiently recovering dmf from wastewater

A waste water and high-efficiency technology, applied in organic chemistry, carboxylic acid amide separation/purification, etc., can solve the problems of affecting the use of recycled DMF, low DMF recovery rate, and high formaldehyde content, achieving low cost, high extraction efficiency, and reduction of ammonia nitrogen and nitrogen. Effects of COD Concentration

Active Publication Date: 2020-08-25
APELOA PHARM CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the need to vaporize a large amount of water during the operation, especially when the DMF content is low, more water needs to be removed by rectification, and the energy consumption is larger; when more water is removed, the solubility of the salt drops rapidly and crystallizes, resulting in rapid kettle temperature After the temperature exceeds 90 ° C, DMF will decompose when there is water, resulting in a low recovery rate of DMF
When the waste water contains formaldehyde at the same time, it will also lead to high formaldehyde content in the recovered DMF, which will affect the use of recovered DMF

Method used

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  • A device and method for efficiently recovering dmf from wastewater

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] like figure 1 As shown, a device for efficiently recovering DMF from wastewater includes reboiler H101a, extraction tower T101, reboiler H101b, static mixer X101, static stratification tank V101, rectification tower T102 and vacuum rectification tower T103; the DMF wastewater containing salt and formaldehyde is used as the light phase F and preheated by the reboiler H101a from the bottom of the extraction tower T101; the extractant is injected as the heavy phase S from the top of the extraction tower T101 after being preheated by the reboiler H101b, The light and heavy phases are countercurrently contacted in the tower for multi-stage extraction; the transfer of DMF from the water phase to the organic phase is completed in the extraction tower T101, the raffinate phase R is extracted from the top of the extraction tower T101, and the extraction phase E containing DMF is extracted from the extraction tower T101 Extracted from the bottom; the extract phase and water enter...

Embodiment 2

[0014] The present invention also provides a kind of efficient recovery DMF method from waste water, comprises the following steps:

[0015] Step 1: DMF waste water containing salt and formaldehyde is taken as light phase F and preheated through reboiler H101a and enters from the bottom of extraction tower T101;

[0016] Step 2: The extractant is injected as the heavy phase S from the top of the extraction tower T101 after being preheated by the reboiler H101b, and the light and heavy phases are countercurrently contacted in the tower for multi-stage extraction;

[0017] Step 3: Complete the transfer of DMF from the aqueous phase to the organic phase in the extraction tower T101, the raffinate phase R is extracted from the top of the extraction tower T101, and the extraction phase E containing DMF is extracted from the bottom of the extraction tower T101;

[0018] Step 4: The extraction phase and washing water enter the static mixer X101 according to a certain volume ratio, an...

Embodiment 3

[0030] On the basis of above-mentioned embodiment, further specifying, the stage number of extraction tower T101 is 10, and rotating speed 45r / min, rectifying tower T102 plate number is 30, and T103 plate number is 20, and the content of DMF in the DMF waste water is 10 %, containing 2.4% formaldehyde, 5% salt, the temperature entering the extraction tower T101 is 40°C, the two-phase volume ratio of the extractant / raw wastewater is 2.0, the temperature of the extractant entering the tower is 30°C, and the extracted from the top of the extraction tower The raffinate phase was analyzed by high-efficiency gas chromatography. The content of water was 91.20%, the content of DMF was 0.12%, the content of dichloromethane was 1.15%, the content of formaldehyde was 2.12%, and the content of salt was 5.4%. The extraction efficiency of the extraction tower was 98.8%. The washing water enters the static mixer X101 according to 20% of the volume of the extraction phase and mixes it into the...

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Abstract

The invention provides a device and a method for recovering DMF (N,N-dimethylformamide) from waste water containing salt and formaldehyde with an extraction and distillation combined technology. The method comprises steps as follows: DMF in the waste water is extracted to an organic phase through organic solvent extraction, the organic phase containing DMF is washed with water in certain proportion, formaldehyde in the organic phase is washed away, an aqueous phase obtained through washing is reused to the raw waste water for continuous extraction, and an extracting agent and DMF are recovered from an organic layer obtained after washing through distillation; a recovered extracting solvent is recycled, and the aqueous phase for washing formaldehyde is combined with raw water for continuous recovery of DMF. The device and the method are particularly suitable for treating low-concentration DMF waste water containing salt and formaldehyde, wherein the DMF content is lower than or equal to 30%, the formaldehyde content is lower than or equal to 5%, and the salt content is lower than or equal to 20%; the process can solve the problem of difficulty in DMF recovery of the waste water containing salt and formaldehyde, reduces energy consumption in a waste water treatment process while guaranteeing the DMF recovery rate, and has remarkable practicability and economic benefits.

Description

technical field [0001] The invention belongs to the technical field of waste water recovery, and in particular relates to a device and method for efficiently recovering DMF from waste water. Background technique [0002] N,N-Dimethylformamide (DMF) is a colorless and transparent liquid with strong polarity and low toxicity. It is miscible with water, alcohols, esters, ketones, ethers, unsaturated hydrocarbons and aromatic hydrocarbons. Known as "universal solvent", it is widely used in petrochemical, organic synthesis, pharmaceutical, pesticide, synthetic fiber, artificial leather and other fields, so a large amount of DMF wastewater will be produced in the chemical production process. At present, the industry adopts rectification method to treat high-concentration DMF wastewater, and adopts multi-effect rectification or pressure swing rectification method to recover low-concentration DMF wastewater. This recovery method not only has low yield, but also consumes a lot of ene...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C231/24C07C233/03
CPCC07C231/24C07C233/03
Inventor 江海波刘培培毛海舫姚跃良李金海何华兰何芳
Owner APELOA PHARM CO LTD