Decoupling Dual Composition Controllers 1. Steady State Results

In this paper the steady state aspects of a new approach to dual composition control are presented. Dual composition control is achieved by controlling a function of the distillate and bottoms purities. The material balance variable, D or B, is used to control a linear combination of product purities. The energy balance variable, V or L, is used to control separation factor. For a very wide range of towers this approach yields only one-way coupling between the loops. The rationale behind using the approach presented is discussed.