Nonlinear Modeling and Cascade Control Design for Multi Effect Falling Film Evaporators

Due to increasing application of multi effect falling film evaporators in food industry, the exact modeling of these processes is important. The aim of this paper is use ability of nonlinear modeling in determining falling film evaporator state variables. Because of large time delays and process disturbances, the tight exact control of product concentration is difficult. By using the nonlinear modeling, the control of three effect falling film evaporator with the use of cascade control algorithm is analyzed. This paper discusses the application and design of a cascade algorithm to control the product concentration in a milk powder three effect falling-film evaporator. It has been shown that the disturbance rejection properties can be significantly improved with cascade control while still maintaining the tracking properties.