What is the specific role of the second solvent in aromatic extraction?
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One stream of the solvent is directed to the feed of the stripping tower as a second solvent. Its purpose is, first, to be used when the aromatic content is high, which is understandable; secondly, it increases the solubility of the solvent, which facilitates the separation of non-aromatic compounds in the stripping tower As I understand it, increasing solubility shouldn’t it reduce selectivity? That wouldn’t be favorable for separation. I saw a post before saying that reducing relative volatility should increase selectivity, right? I mainly want to understand how the second solvent affects the relative volatility – what’s the principle behind it?
Great master \ud83d\ude4f\ud83c\udffb, I understand what you mean. I’d like to ask: I know how to increase the relative volatility and solubility. What I’m wondering is why the relative volatility increases. I’ve checked that relative volatility refers to the ratio of the volatility of the volatile component to that of the less volatile component. So why does the amount of the second solvent added affect the ratio of the volatility of non-aromatic compounds to that of aromatic compounds in the solvent?
One solvent is sufficient; why add a second one as well? In the extraction tower, a pure solvent is used to separate the non-aromatic compounds from the top downward
Yes, normal primary solvents are fine; their presence is reasonable. Using a second solvent is still effective when the aromatic content in the feed exceeds 65%. I mainly want to understand how the relative volatility is affected
Our aromatics have always been above 65, and a certain solvent works very well
More solvent helps to better dissolve the aromatics in the stripping tower, thereby separating out the non-aromatics; that makes sense