FLEXIBILITY ANALYSIS AND DESIGN OF DYNAMIC PROCESSES WITH STOCHASTIC PARAMETERS

In this paper, we present theoretical developments for the analysis an d design of linear dynamic process systems in the presence of uncertai n parameters, described by Gaussian probability distribution functions . The concept of the stochastic flexibility index, as a metric for qua ntifying the ability of a process to maintain feasible operation in th e face of stochastic uncertainties, is first extended to linear dynami c models. A detailed procedure for evaluating the stochastic flexibili ty over time, is then outlined. This procedure fully exploits the math ematical properties of the system to enable derivation of analytical e xpressions describing the dynamic feasible region. These expressions a re then used as constraints in a single-stage design formulation for t he determination of an economically optimal process design that meets a desired stochastic flexibility target over the entire time horizon o f interest. With this formulation, the trade-offs between cost and tar get flexibility can be investigated. A numerical example is used to de monstrate the potential of the techniques. (C) 1998 Elsevier Science L td. All rights reserved.