Control Loop Pairing and Interaction Analyses of the Falling Film Evaporator Process

The paper solves the control loop pairing problem of the falling evaporator process. To this end, we derive a dynamic input-output model by taking dominant time-delays into account. Besides classical methods to solve the loop pairing problem, such as Bristol's relative gain array or the Niederlinski index, we apply modern approaches, namely, the participation matrix and Hankel interaction index array. Since the former only focus on multiloop single-input-single-output control, the latter additionally give recommendations regarding the structure of a multivariable controller. On the one hand, we show a feasible pairing for multiloop single-input-single-output process control but, on the other hand, we conclude a triangular structure of a multivariable controller, which may achieve better results due to the strong interaction of two control loops.