Recent results in optimal reactor synthesis via attainable region theory

In consideration of (isothermal) reactor designs involving only chemical re action and mixing, Feinberg and Hildebrandt (1997, Chem. Engng Sci. 52, 163 7-1665) showed that the set of all attainable composition vectors (the atta inable region) has a certain universal character. In particular, manifolds of extreme: points (protrusions) on the attainable region's boundary are in variably made up of plug-flow reactor trajectories. These trajectories ther efore form a system of PFR "highways" that provide access to the attainable region's extreme points. They also showed that, in a certain sense, CFSTRs and differential sidestream reactors (DSRs) provide means to navigate alon g the attainable region's boundary to a PFR trajectory of choice. Here we c onsider the special character of DSR trajectories that reside on the attain able region's boundary. Ideas from geometric control theory indicate that c ritical DSRs of this kind must conform to a very special sidestream additio n rate policy. Indeed, highly detailed equations that govern such a policy can be written in terms of the sidestream composition and the reaction kine tics. (C) 1999 Elsevier Science Ltd. All rights reserved.