Simulation and control of a multiple effect evaporator

Sugar production contains a number of unit operations in series. The most energy consuming unit is the evaporation process. The aim of this paper is to describe the development of a concept to control the product quality and the energy consumption in the evaporation process. Despite extensive use in sugar production the multiple effect evaporator has been a difficult system to analyze and control. To investigate the control strategies a real time simulator has been developed. Using the simulator, a control scheme has been designed and implemented. The control system is based on the idiomatic concept. The problem is to derive proper strategies for decomposing the process into smaller independent functions, and to synthesize control actions which achieve and maintain those functional structures. These structures are controlled using well known strategies (idioms). The control concept has been tested on the real time simulator and with minor modifications it has been implemented in a Danish sugar plant.