Effect of competing reversible reactions on optimal operating policies for plants with recycle

Abstract

A simple classification procedure for determining optimal steady-state operating policies for plants with recycle has recently been developed by Griffin et al. to cover complex process chemistries. (Griffin, D. W.; Mellichamp, D. A.; Doherty, M. F. AIChE J. 2008, 54, 2597). This procedure classifies a process chemistry into one of two groups of operating policies based solely on the reaction kinetics. The optimal operating policy for a bounded chemistry is to operate the reactor completely full for all production rates while a nonbounded chemistry may have a variable reactor volume subject to system constraints. The current work focuses on process chemistries with reversible reactions and demonstrates that the optimal operating policy can change depending on which reaction(s) is(are) reversible and the magnitude of the equilibrium constant(s). Process chemistries with a reversible desired reaction also exhibit multiple steady-states, but only one of the steady-states corresponds to feasible operating conditions. © 2009 American Chemical Society.