What causes the decrease in the pH value of the solvent in the benzene extraction unit?
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Sulfolane is being used, and the pH value keeps dropping. After adding monoethanolamine, the pH rises above 6, but it drops by 4-5 units again after just two or three days. The system pressure remains stable, a positive pressure is maintained, and no leaks are detected. Could it be that the solvent needs to be replaced, or is there some other reason? Please advise, experts! ! !
Reason: 1. The sulfolane regeneration temperature is too high； 2. Accumulation of chloride ions in the raw materials
The regeneration temperature is generally around 170 degrees; there are no chloride ions in the raw material
The benzene extraction feedstock comes from the reforming dehexane tower; the reformate oil contains trace amounts of chlorine.