Decentralized control of the tennessee eastman process

Abstract

Tennessee Eastman problem was proposed by Downs and Vogel. It is based on the real industrial chemical process and the Fortran code provided by Downs and Vogel represents this process. This process includes five unit operations : a reactor, a product condenser, a vapor-liquid separator, a recycle compressor and a product stripper. It has 12 valves available for manipulation and 41 measurements available for monitoring or control. Two products and two byproducts are produced by four gas phase reactions from four reactants. There are four setpoint changes and 20 disturbances in this process. Therefore, it is an objective to develop a control strategy to overcome the given setpoint changes and disturbances. In this study, decentralized control system using PID controller is used to control this process. The proposed control strategy begins with the selection of the method for production rate control. The production rate is controlled by manipulating the setpoint of feed flow rate with the feedback control loop based on material balance. Second, levels and pressure are controlled. The stripper level is controlled by the stripper bottom flow rate, the separator level by the separator bottom flow rate and the reactor level by using the temperature relation between the condenser cooling water flow rate and the separator. The reactor pressure is controlled by the purge flow rate. The product composition is controlled by the feedforward control using the steady-state value and the feedback control using the measurements of the reactor feed analyzer and the product analyzer. The reactor temperature is controlled by the reactor jacket cooling water flow rate. The proposed control system was tested with 20 disturbances and 3 setpoint changes except for purge gas composition of component B changes. The results of regulatory problems and servo problems shows better performance than the strategy proposed by Ricker for the base case.