Acidity of the extraction solvent
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In the extraction unit, the pH of the sulfolane analysis gradually decreased to 6.6, but the temperature of the unit never exceeded 180°C. What is the reason for this? Is it necessary to increase monoethanolamine to adjust the pH?
Where does the stripping water come from? Has an analysis been done?
Do you use distillation extraction or liquid-liquid extraction? Distillation extraction involves the use of stripping water and blending solvents; the degradation of sulfolane does not necessarily require a temperature above 200°C, as even trace amounts of oxygen in the system can cause its degradation. Adding ethanolamine in the early stages is effective, but if it is continued to be added later on, it becomes ineffective once a certain amount has been reached.
We have been using it for 5 years; we only added monoethanolamine in the second year. How can micro-oxygen levels be measured?
Check the sealing performance of your extraction negative pressure system – that is, stop the steam extractor and see how long the negative pressure can be maintained. Also examine the pressure control system of the extraction feed tank to determine whether any air has mixed into the feed.
Original poster, do you take samples of the lean solvent on a regular basis for inspection? If the pH value is on the acidic side, it’s possible that the solvent has begun to degrade and break down; take a sample of the lean solvent and check its color and appearance before making a decision
The color is close to brown; it is transparent, though