Superheated boilup

What happens if the reflux liquid is subcooled or the boilup vapor is superheated We have already looked at two similar cases where we have a subcooled liquid or a superheated vapor feed, hi those cases we found that a subcooled liquid would condense some vapor in the column, while a superheated vapor would vaporize some liquid. Since reflux and boilup are inputs to the column, we should expect exacdy the same behavior if these streams are subcooled or superheated. 

A superheated direct steam input or a superheated boilup from a total reboiler will cause vaporization of liquid inside the column. This is equivalent to a net increase in the boilup ratio, E/B, and makes the slope of the stripping section operating line approach 1.0. Since superheated vapor inputs can be analyzed in the same fashion as the subcooled liquid reflux, it will be left as homework assignments 4.C14 and 4.C15. 

Include the effects of subcooled reflux or superheated boilup in your McCabe-Thiele and Lewis analyses... 

C12. Show how to determine (V/B). Derive an equation for calculation of (V/B) from (L/V). C13. Sketch the McCabe-Thiele diagram if the Murphree liquid efficiency is constant and Ej g = 0.75. C14. Derive the equations to calculate L/V when a superheated boilup is used. 

D26. A distillation column with a partial condenser and a total reboiler is separating acetone and ethanol. There are two feeds. One feed is 50.0 mol% acetone, flows at 100.0 mol/min, and is a superheated vapor where approximately 1 mole of liquid will vaporize on the feed stage for each 20 moles of feed. The other feed is a saturated liquid, flows at 150.0 mol/min and is 35.0 mol% acetone. We desire a distillate product that is = 0.85 mole fraction acetone and a bottoms product that is Xg = 0.10 mole fraction acetone. The column has a partial condenser and a total reboiler. Boilup is returned as a saturated vapor. Column operates at a pressure of 1.0 atin. Assume CMO and use a McCabe-Thiele diagram. VLE data are given in Problem 4.D7. 

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