Nonlinear control of an evaporator using an error trajectory technique

This paper outlines the successful application of an adaptive control metho d in an industrial environment. The control strategy incorporated MRAC (Mod el Reference Adaptive Control) using an adaptive PID where the adaptive par ameter was estimated using a macroscopic energy balance over the control zo ne based on the concept of a tracking error trajectory. Success is demonstr ated in a plant for sugar production where the formation of candy, due to i ncorrect management, the steam flow to the evaporators prevented the sugar syrups leaving the system to pass to the centrifugal screens. This stopped production three or four times a day for 30 min, leading to serious problem s in relation to cost and quality, the evaporators being very sensitive to temperature changes. (C) 2000 Society of Chemical Industry.