Several issues regarding the effects of changes in the feed concentration of a distillation column
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Firstly, the answers to these questions can be found in the book as well; it’s just that the calculation basis isn’t provided. Therefore, I hope everyone can give the calculation process. The first question is: when the feed concentration decreases while everything else remains unchanged, including the discharge volume and concentration, I know whether the minimum reflux ratio increases or decreases, but I can’t find a basis for this calculation; it’s not possible to determine it either by drawing diagrams. Second, the feed concentration decreases while the temperature and flow rate remain unchanged. With the outlet amounts at the bottom and top of the tower remaining constant, how does the concentration change? The book states that the concentration decreases, but my calculations suggest that it might not necessarily change; I’m looking for the basis for this calculation
As the feed concentration decreases and the light components increase, if there are multiple feed inlets, these inlets should be moved upward, resulting in a reduced reflux volume (and a lower reflux ratio)； As the feed concentration decreases while the temperature and flow rate remain unchanged, if the discharge amounts at the bottom and top of the tower stay the same, the excess light components will inevitably lead to an increase in the light components at both the bottom and top of the tower, resulting in a decrease in their concentration.
Thank you, but I need the specific calculation process, such as drawing diagrams or using formulas for comparison