Hello, I have a question regarding Murphree efficiences and the associated McCabe-Thiele diagram. In partial reflux distillation, should I include the reboiler stage when stepping down (i.e. determining the # of stages) from the distillate to the bottoms composition? Or should I just use the total number of trays and forget the reboiler stage? My friend asked a professor this question last semester and he told my friend to forget the reboiler. This doesn't make sense to me because if you do not include the reboiler stage then the diagram suggests the bottoms composition (the one coming from the reboiler) is the composition coming out from the last tray. Here's the image of my current McCabe-Thiele diagram: http://img434.imageshack.us/my.php?image=one8xh.jpg Thanks.