Suppose that the distillation column shown in figure has been designed to separate a methanol-water mixture that

Question:

Suppose that the distillation column shown in figure has been designed to separate a methanol-water mixture that is .50% methanol (MeOH). This high purity column has a large number of trays and a nominal distillate composition of xD = 5 ppm of MeOH. Because a composition analyzer is not available, it is proposed to control xD indirectly by measuring and controlling the liquid temperature at one of the following locations:(a) The reflux stream.(b) The top tray in the rectifying section.(c) An intermediate tray in the rectifying section, midway between the feed tray and the top tray. Discuss the relative advantages and disadvantages of each choice based on both steady-state and dynamicconsiderations.