Control design for an industrial distillation column

Abstract

Control design of industrial distillation columns is a well-known problem. The diversity of columns makes a general approach impractible. Non-linearities, multivariable character and possible time delays of individual columns are the source of the control design problems. This paper discusses a process anlaysis and control design procedure for industrial binary high-purity distillation columns. Use is being made of both mechanistic modelling and process identification. It is shown that the procedure, as applied, permits rapid evaluation of several types of control strategies, ranging from PID control and physical decoupling to mathematical decoupling and model-based control. It was proven that multivariable control leads to improved control performance for the application considered. Furthermore it is shown that by model-based process analysis and basic control design, complex control problems can be significantly reduced.