Economics of a Reactor-Column Process

Of course, there is additional capital investment in the distillation column and its associated heat exchangers (condenser and reboiler) and most importantly, there will be an energy cost to provide heat to the reboiler. We neglect any energy cost in the 

This reactor-column process has several degrees of freedom that can be adjusted to satisfy some economic objective. The most important is the size of the reactor. The smaller the reactor, the larger the column and the recycle flow. 

The same kinetic case considered in the previous section is used in the reactor. The reactor effluent F (with composition z) is fed to a stripping column that sends the lighter component A out the top as a recycle stream and the heavier component B out the bottom as the final product stream. A stripping column is used, as opposed to a full column with reflux, because previous studies have shown that a stripper is the optimum economic design. Since the overhead is not a product stream, it does not have to have a high purity. The vapor going overhead is condensed and pumped back to the reactor at a molar flowrate D and composition xD. The liquid rate in the stripper is F and the vapor rate is D. 

The vapor-liquid equilibrium (VLE) is assume to be described by a constant relative volatility between components A and B of a= 1.5. On each tray in the column, the compositions (mole fraction A) of the liquid x and vapor v are related as follows  

The design of the stripper is based on finding the pinch point between the VLE line and the operating line. If the feed is saturated liquid, this occurs at vmax  

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