On the application of tuning regulators to control a commercial heat exchanger

The synthesis of a practical controller for a commercial heat exchanger using tuning regulators [17] is described in this paper. The problem considered is to find a robust feedback-feedforward controller so that the output temperature and output flow of the heat exchanger are satisfactorily regulated, independent of any variations in input flow, input temperature, etc. of the process. In this control design problem, it is assumed that a mathematical model of the heat exchanger is not available, i.e., the process which is to be regulated is unknown. In this case, on using the approach outlined in [17], some simple "off-line" experiments are applied to the heat exchanger, and from the results of these experiments it is determined that a solution to the problem exists; a controller is then obtained using the results of these experiments and by applying some simple "on-line" tuning experiments. This paper describes these experiments, the results of performing the on-line tuning, and the final control configuration obtained. It is found that the new controller obtained performs extremely satisfactorily and is superior to the "conventional" controller for the process.