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Apparatus and method for recovering perfluorocapylic acid from fluorine-containing polymer dry tail gas

A technology for perfluorooctanoic acid and tail gas drying, applied in the separation/purification of carboxylic acid compounds, organic chemistry, etc., can solve the problems of perfluorooctanoic acid accumulation, high investment and operating costs, and achieve good recovery effect, high practical value, and short process flow

Active Publication Date: 2018-07-06
ZHONGHAO CHENGUANG RES INST OF CHEMICALINDUSTRY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This type of method needs to be put into the exhaust gas absorption tower, which has high investment and operation costs, and PFOA is easy to accumulate in the hot air pipe before entering the absorption tower

Method used

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  • Apparatus and method for recovering perfluorocapylic acid from fluorine-containing polymer dry tail gas

Examples

Experimental program
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Embodiment 1

[0038] Such as figure 1 . This embodiment provides a device for recovering perfluorooctanoic acid from the tail gas of dried fluoropolymers, including a vacuum oven, a buffer tank, a water ring vacuum pump, a water tank, a distillation tower, and a rectification tower connected in sequence; wherein the water ring vacuum pump passes The heat exchanger and the water tank form a water circulation unit;

[0039] In the recovery device of the present invention, the connecting pipeline between the vacuum oven and the buffer tank needs to extend from the top of the buffer tank to the middle of the buffer tank, so as to ensure that PFOA is fully condensed in the buffer tank and improve its recovery rate.

[0040] The buffer tank does not need to be insulated, but part of the insulation is carried out at the part of the pipeline connected to the inlet of the buffer tank to adjust the temperature of the buffer tank.

[0041] The heat exchanger is selected from plate condensers.

[00...

Embodiment 2

[0044] This embodiment provides a method for recovering perfluorooctanoic acid in polytetrafluoroethylene vacuum drying tail gas by using the recovery device described in embodiment 1, the steps are as follows:

[0045] 1) After the fluorine-containing polymer is dried in a vacuum oven, its tail gas enters the buffer tank for vacuum concentration, and most of the perfluorooctanoic acid in the tail gas is enriched at the bottom of the buffer tank to form a concentrate;

[0046] Among them, it takes about 3 hours for the temperature of the vacuum oven to rise from normal temperature to 120°C. During this time, most of the water entrained in the resin is evaporated, and the surfactant ammonium perfluorooctanoate will be decomposed into perfluorooctanoic acid and ammonia. PFOA has a low boiling point and is therefore evaporated first, while PFOA remains in the resin due to its high boiling point. The water vapor, ammonia will be partially condensed in the buffer tank. At 120-140°C,...

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Abstract

The invention relates to an apparatus and method for recovering perfluorocapylic acid from fluorine-containing polymer dry tail gas dried by a vacuum baking oven. The apparatus comprises a vacuum baking oven, a buffer tank, a water-ring vacuum pump, a water tank, a distillation column and a rectifying tower which are connected in sequence, wherein the water-ring vacuum pump and the water tank forma water circulation unit through a heat exchanger. When applied to recovery of perfluorocapylic acid, the apparatus is good in recovery effect and short in process flow; a high-concentration perfluorocapylic acid concentrate enriched in the buffer tank can be directly used or be subjected to further rectification so as to obtain perfluorocapylic acid; moreover, a small amount of perfluorocapylicacid in circulation water can be effectively recovered after distillation and rectification. With the recovery apparatus and method in the invention, the recovery rate of perfluorocapylic acid is 72%or so and the purity of recovered perfluorocapylic acid is greater than 99.8%, so the recovery apparatus and method have high practical value.

Description

technical field [0001] The invention belongs to the field of chemical waste gas treatment, and specifically relates to a method and equipment for enriching and recovering perfluorooctanoic acid from tail gas of dry fluorine-containing polymers. Background technique [0002] Common drying methods for fluoropolymers mainly include vacuum drying and hot air circulation drying. Among them, in the vacuum drying method, the fluorine-containing polymer is heated to 120-200° C., and the moisture, ammonium perfluorooctanoate and perfluorooctanoic acid are evaporated and gradually sucked away with vacuuming. In order to prevent the pollution of PFOA, it is necessary to recover the PFOA in the tail gas of dry fluoropolymer. [0003] In the prior art, absorption towers are mainly used to absorb PFOA. In CN201310332105.2, the tail gas containing perfluorooctanoic acid vapor is absorbed by the absorption liquid, and the perfluorooctanoate in the absorption liquid after absorbing perfluo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/42C07C53/21
CPCC07C51/42C07C53/21
Inventor 叶飞杨李岗郑洪伟蒋玉超段绍书汪永红
Owner ZHONGHAO CHENGUANG RES INST OF CHEMICALINDUSTRY CO LTD