Constrained multivariable control of a distillation column using a simplified model predictive control algorithm

Distillation columns are important process units in petroleum refining and need to be maintained close to optimum operating conditions because of econ omic incentives. Model predictive control has been used for control of thes e units. However, the constrained optimization problem involved in the cont rol has generally been solved in practice in a piece-meal fashion. To solve the problem without decomposition, the use of a linear programming (LP) fo rmulation using a simplified model predictive control algorithm has been su ggested in the literature. In this paper, the LP approach is applied for co ntrol of an industrial distillation column, The approach involved a very sm all size optimization problem and required very modest computational resour ces. The control algorithm eliminated the large cycling in the product comp osition that was present using SISO controllers. This resulted in a 2.5% in crease in production rate, a 0.5% increase in product recovery, and a signi ficant increase in profit. (C) 2001 Elsevier Science Ltd. All rights reserv ed.