Actual operation status of the deep desorption unit for chloroethylene synthesis wash acid wastewater
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Control the amount of water added at the top of the vinyl chloride synthesis wash tower; a small portion of the wash waste acid is used for neutralizing the alkali wash wastewater, and conventional desorption should be sufficient to maintain a balanced cycle of the by-product waste acid. In recent years, some companies have also installed deep desorption units. Are these units in operation continuously or only intermittently, and what is their actual performance? Please share and discuss.
When a conventional hydrochloric acid treatment unit is installed, a zero-removal unit should also be set up, so that the acid level can remain balanced. Using the acid waste from washing processes for neutralizing the alkali wash tower, as you suggested, is not appropriate; instead, a combined tower should be used.
Neutralizing the alkali wash wastewater always requires a small amount of waste acid; therefore, as long as the flow rate of the fresh water absorbent added at the top of the absorption tower is properly controlled, conventional desorption should be sufficient to maintain a balanced cycle of the by-product acid, without any excess dilute acid being generated. Of course, catalyst dust and other particles in the waste acid should be filtered out to prevent accumulation and blockages.
Regarding the same question, under low-load operation of the unit, the amount of acid produced by conventional desorption is low; therefore, it is worth considering the option of neutralizing the waste acid, and it may be necessary to employ advanced desorption methods.
The neutralization of spent alkaline solutions requires treatment of mercury-containing wastewater, and there isn’t really that much of this spent acid. Concentrated hydrochloric acid treated by conventional desorption can maintain circulation at low loads, but the desorption of 31% hydrochloric acid to 21% hydrochloric acid is limited by the capacity of conventional desorption units; when this capacity is exceeded, balanced circulation becomes impossible, and it is necessary to use advanced desorption units, transfer the material outside, or consider other neutralization methods.
If the 22% dilute acid obtained through conventional stripping is not subjected to further stripping and is relied on solely on a foam tower for absorption, it cannot be completely absorbed