Distillation wastewater COD
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Please tell me why the COD of distillation wastewater always exceeds the standard? When sampling, it was 99.9%, no problem. Now the COD is 8000+
Although the methanol content is low, there will be some high boiling point fusel alcohols in it, and the COD will certainly not be low.
How to deal with this high boiling point fusel alcohol? Sometimes our COD will drop to over 1,000 for no apparent reason.
High boiling point fusel alcohols are generally controlled based on the side line extraction. When the COD you mentioned decreases, it should be that the temperature of the side line extraction sensitive point is higher. As the fusel alcohols move up, there will be less fusel alcohols in the wastewater at the bottom of the tower. There is no way to deal with the fusel alcohols in the wastewater. Isn’t this wastewater going to gasification and coal grinding as supplementary water?
Our wastewater goes to sewage treatment, so it is more sensitive. Our atmospheric tower does not have lateral production. There is a recycling tower. What you said makes sense. Can you tell me what the lateral extraction of the atmospheric tower looks like?
Since your normal pressure tower does not have side extraction, you need to control the temperature of the sensitive point to be low and press the fusel alcohol to the tower still. Then the normal pressure tower still cannot be sent out directly. Instead, the wastewater from the stripper still should be sent out after being stripped in the stripper. As for the side line extraction of the atmospheric tower, it is the same as the side line extraction of the stripping tower. The purpose is to extract fusel alcohols such as ethanol and ensure product quality.
Distillation generally uses a three-tower process or a four-tower process, and the older ones have two towers. MTO has only one tower.
Fusel alcohol must be extracted from the side line. If not, it will accumulate in the atmospheric tower, which will cause high resistance to a certain extent or flow down, causing the residual COD to become unstable and exceed the standard.