Condensed water recycling system for evaporation process

Abstract

The invention relates to the field of industrial sewage recycling and particularly relates to a condensed water recycling system for an evaporation process. The condensed water recycling system comprises an evaporation device, a condenser, a process condensed water tank and an electrolyzer cathode chamber which are connected sequentially; condensed water generated by the evaporation device and the condenser is conveyed to the electrolyzer cathode chamber to serves as a diluting medium, so that process condensed water is recovered effectively; a first pH meter and a first flowmeter are arranged on a pipeline which connects the process condensed water tank and the electrolyzer cathode chamber together, so that the flow and pH value of the condensed water entering the electrolyzer cathode chamber are monitored; and since a pipeline leading to a primary brine refining unit is connected with a pipeline between the first pH meter and a first control valve, the process condensed water is discharged to the primary brine refining unit and used for desalting when the pH value of the process condensed water does not meet the requirement, so that the process condensed water is treated and utilized effectively, and further the comprehensive and efficient utilization of the process condensed water is realized.

Description

technical field [0001] The invention relates to the field of recycling industrial sewage, in particular to a system for recycling condensed water in an evaporation process. Background technique [0002] In recent years, in the development of my country's chlor-alkali industry, ionic membrane electrolyzers are gradually replacing diaphragm electrolyzers and mercury electrolyzers, and the concentration of alkali produced by ionic membrane electrolyzers can directly reach 32%. In order to maintain a stable concentration of alkali solution at the outlet of the cathode chamber of the electrolyzer and take away the heat generated inside the electrolyzer, it is necessary to add some pure water as a dilution medium to the circulating liquid entering the cathode chamber of the electrolyzer, and to precisely control the amount of pure water added. Otherwise, it will cause the deviation of the cathode lye concentration. For an ion-exchange membrane electrolysis device with a productio...

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Problems solved by technology

For an ion-exchange membrane electrolysis device with a production capacity of 200,000 tons / year, the amount of pure water used for the cathode of the electrolyzer is about 25m 3 / h, the operating pressure of the pure water station is high

At the same time, in the chlor-alkali plant, in the process of obtaining caustic soda products with different concentrations, the evaporation device and the condenser will produce a large amount of condensed water, which is usually not effectively utilized but discharged as sewage, causing pollution to the environment. And it will also waste a small amount of lye contained in these condensed water. Therefore, in the chlor-alkali industry and even other chemical companies, how to reduce the consumption of pure water and reduce the discharge of process condensed water, so as to solve the problem of water balance is the biggest problem facing the industry. problem

[0003] At present, although some data show that industrial condensed water can be used as pure water for electrolysis, there is a lack of corresponding implementation measures, and because the process has strict requirements on the pH and addition amount of the dilution medium entering the electrolyzer, if the requirements are not met, the ions will be destroyed. Therefore, how to ensure that the process condensed water entering the cathode chamber of the electrolytic cell meets the requirements and how to effectively deal with the process condensed water that does not meet the requirements is an important problem facing the recycling and utilization of process condensed water in the chlor-alkali industry.

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