Sometimes the equilibrium curve does not look really curvy. The more curvy the equilibrium curve is, the better is the separation of the key components. Previously we already learned how to determine the minimum reflux ratio in case of an easily-separated mixture. This time we will discuss how to determine the same parameter when the equilibrium curve differs or gets less curvy.
Example:
Notice that the equilibrium curve gets closer to the bisecting line as X-value approaches one. This is a completely different mixture in comparison to the one that we used as an example in the previous entry.
First step is to mark all those given compositions such bottom-, feed- and distillate composition. In reality only the distillate composition is required. However there is no harm in marking all those points on the diagram.
Secondly from that distillate composition draw a tangent to the curve and extrapolate it until we have the value of y-intercept, a.
Since we know a is equal to xd/(v+1) , we can easily determine its minimum reflux ratio, provided xd is known before.
Example:
Notice that the equilibrium curve gets closer to the bisecting line as X-value approaches one. This is a completely different mixture in comparison to the one that we used as an example in the previous entry.
First step is to mark all those given compositions such bottom-, feed- and distillate composition. In reality only the distillate composition is required. However there is no harm in marking all those points on the diagram.
Secondly from that distillate composition draw a tangent to the curve and extrapolate it until we have the value of y-intercept, a.
Since we know a is equal to xd/(v+1) , we can easily determine its minimum reflux ratio, provided xd is known before.
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