pH of low-temperature methanol washing wastewater
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There is a problem with our process； Non-condensable gas is drawn from the pre-distillation column to the inlet of the off-gas scrubber; it has been in operation for about 40 days now. The pH has increased from 5.5–6.5 before to 7–8 now; please discuss the reasons for this!
Has ammonia accumulated in the system?
Are you referring to the wastewater discharged from the bottom of the five towers, or those from the bottom of the six towers? Could you explain it more clearly?
If the landlord is referring to the pH value of the washing water at the bottom of the exhaust gas scrubber, it shouldn’t be that high!
I’m sorry: I caused everyone to misunderstand. By PH, I mean the pH of the wastewater at the bottom of the methanol-water separation tower. The ammonia accumulation in the system is not high, and it remains within the specified limits.
May I ask the original poster, how many years have you been in operation? Before the modification, was the pH value of the wastewater from the methanol-water separation tower between 5.5 and 6.5? Is it because the addition of non-condensable gas from distillation causes the pH value to rise? ? The distillation non-condensable gas contains acidic substances; their dissolution in the exhaust gas scrubber will lower the pH of the washing water. Bringing this water to the methanol-water separation tower may result in a slight decrease in pH, but it should not cause an increase in pH! In our original system, no alkali was added to the methanol-water separation tower, and the pH value remained between 7 and 8!