Steady State Design

Typical design variables of a reactive distillation column include column pressure P, number of reactive trays Nrx, number of trays in the stripping NS and rectifying NR sections, and the locations of the feed trays (NFA and NFB, respectively) as shown in Figure 18.1.

In this work, P is fixed at a constant value and NRX is selected to ensure the desired conversion with the conventional feed arrangement (heavy reactant to the top of the reactive zone and light reactant to the bottom of the reactive zone). The number of trays in the stripping and rectifying sections is set to twice of the minimum number of trays according to the Fenske equation,2 which is

For the rectifying tray number NR we use the liquid composition right above the reactive tray for xB, and for NS we use the vapor phase composition right below the reactive zone as xD. This leaves us with the feed tray locations as the design variables. Because all tray numbers are determined, the effects of feed tray locations can be compared by simply looking at the energy consumption (i.e., vapor boilup rate).

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