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Process for isolating crude terephthalic acid(CTA)

A crude terephthalic acid and acetic acid technology, applied in the separation/purification of carboxylic acid compounds, organic chemistry and other directions, can solve the problems of affecting the normal operation of production, high maintenance costs, and high frequency of alkaline washing

Inactive Publication Date: 2007-07-04
ACTION PERFECT ENG XIAMEN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, the rotary vacuum filter has the problem of crystallization and clogging of the product on the filter cloth due to the pressure drop during filtration, and the frequency of alkali cleaning is very high, which not only causes waste of products and caustic soda, but also affects the normal operation of production
In addition, when the filter cloth is damaged and needs to be replaced, it takes a long time, the repair cost is high, and the output and product quality are affected

Method used

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  • Process for isolating crude terephthalic acid(CTA)

Examples

Experimental program
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Embodiment 1

[0011] Please refer to Fig. 1 for the specific production process of this embodiment. The content of terephthalic acid in the acetic acid-containing mother liquor slurry 111 containing crude terephthalic acid (CTA) crystals is about 32-36%, the temperature is 106°C, and the concentration of the main impurity ash (heavy metals and oxidation reaction by-products) is 500-600ppm, the acetic acid-containing slurry 111 is pressurized at about 2-4kg / cm 2 (gauge pressure) is sent to the hydraulic filter area 11 of the filter 1 and stays in the filter tank of the filter 11 after being filtered to produce a wet filter cake. The filtrate 112 is drawn to the filtrate collection system for recycling. Because the saturation pressure of this slurry 111 is 0kg / cm 2 (gauge pressure), the saturation temperature is 106°C, and the pressure drop of the hydraulic filter zone 11 is about 1kg / cm 2 (gauge pressure), so the pressure and temperature of the filtrate 112 entering the filtrate collection...

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Abstract

The invention relates to a method for separating coarse terephthalic acid. The method takes rotary pressure filterer, and the filterer comprises liquid-pressure filtering, acetate filtering, gas-pressure filtering and feeding function areas. The temperature and pressure for filtering are controlled for not to form crystallization; the filtering cake with humidity rate being lower than 12wt% is dried; the ash concentration in product is less than 60 ppm, and the catalyst using period in later refinery hydrogenation reactors can be prolonged through effective removal of ash. The invention is characterized by stalbe operation, high productivity, low frequency for basic wash, reduced wastewater treating load, low investment and operation cost and saved electricity and steam.

Description

Technical field [0001] The invention relates to a method for recovering crude terephthalic acid from acetic acid-containing mother liquor slurry. Background technique [0002] In the traditional crude terephthalic acid (CTA) manufacturing process, centrifuges or rotary vacuum filters are often used for solid-liquid separation, that is, the slurry in the third crystallization tank is pumped into the centrifuge, and the crude terephthalic acid contained in the slurry is separated by centrifugal force. Terephthalic acid and mother liquor or pre-vacuumized, fully depressurized and cooled (temperature is 90°C, pressure is -0.5kg / cm 2 (gauge pressure)) is sent to the feed tank of the rotary vacuum filter, and then pumped to the bottom hopper of the rotary vacuum filter, and the crystal is suspended in the acetic acid solvent by overflowing part of the slurry, so that The pressure difference will adsorb the crystals on the drum to achieve the purpose of filtration. [0003] Howev...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/42C07C63/26
CPCC07C51/43C07C51/47
Inventor 黄泰平谭伟业范红波
Owner ACTION PERFECT ENG XIAMEN