Method and system for separating sodium carbonate and sodium bromide in PTA oxidation tail gas washing tower discharge liquid

Abstract

The invention relates to a method for separating sodium carbonate and sodium bromide in a PTA oxidation tail gas washing tower discharge liquid. The method comprises the following steps: in a sodium bicarbonate removal tower, adjusting the pH value of the washing tower discharge liquid to be 11.0-12.0 in a steam heating or sodium hydroxide adding manner to obtain a decarbonized washing tower discharge liquid; conveying the decarbonized washing tower discharge liquid to an ultrafiltration device to remove suspended particulate matters so as to obtain ultrafiltration produced water and ultrafiltration concentrated water, and discharging the ultrafiltration concentrated water; and conveying the ultrafiltration produced water to a two-stage nanofiltration device and a two-stage RO device, wherein the first-stage nanofiltration concentrated water is a sodium carbonate-containing solution, and the first-stage RO concentrated water is a sodium bromide-rich solution. The invention relates to a system for separating sodium carbonate and sodium bromide in the PTA oxidation tail gas washing tower discharge liquid. According to the method and the system, sodium bicarbonate in the discharged liquid of the PTA oxidation tail gas washing tower can be converted into sodium carbonate, and the sodium carbonate is separated from sodium bromide.

Description

technical field [0001] The invention belongs to the technical field of resource utilization of bromine-containing wastewater, and in particular relates to an energy-saving decarbonization method and system for the discharge liquid of a PTA oxidation tail gas scrubber, and involves decomposition and removal of sodium bicarbonate in the process of treating the discharge liquid of a PTA oxidation tail gas scrubber Sodium carbonate in the wash effluent is recovered after carbon dioxide. Background technique [0002] PTA (purified terephthalic acid) is one of the important bulk organic products downstream of petrochemical industry. At present, PTA is mainly produced by the air oxidation method of p-xylene. The PTA oxidation tail gas produced in the production process is the organic waste gas containing various pollutants discharged from the oxidation reactor, and is the most harmful gas emitted by the PTA device. Therefore, the effluent from the PTA oxidation tail gas scrubber i...

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Problems solved by technology

[0003] The discharge liquid of the PTA oxidation tail gas scrubber mainly contains sodium bromide, sodium bicarbonate, sodium carbonate, etc., and the concentration of sodium bicarbonate in the discharge liquid of the scrubber is as high as 2.0%, but the cobalt-manganese catalyst recovery device only needs sodium carbonate and does not need carbonic acid Sodium hydrogen carbonate needs to be removed from the effluent of the scrubber. At present, the effluent of the scrubber is directly discharged to the sewage treatment plant as wastewater for treatment. The cost of wastewater treatment is high and a lot of resources are wasted.

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