ABSTRACT
In inferential control, a control scheme uses an inferential variable as the controller measured value. A simple technique of model identification is developed using Lotus 1-2-3; the process input may have any form or shape. An empirical model can be just as good as a model based on mass and energy balances. Model-based control would have to be used in order to make tight control possible. If the temperature was controlled, however, disturbances would mostly be eliminated by the temperature controller. Straight analyser to temperature control could function satisfactorily since temperature and concentration changes would be restricted to a limited operating range, and the process gain would vary only slightly. Assume that the temperature difference has to be controlled by manipulating the inlet temperature. In an effort to minimize energy consumption in distillation towers, many control schemes use pressure minimization.
