New control system for crude oil processing improvement of control qualityand plant operability

Most control loops in many installed control systems use only standard, lin ear PID controllers. Such situations offer the possibility to improve both control quality and plant operability without additional investments. The d esign of the new control system for crude oil processing in the PARAMO refi nery a.s. in Pardubice, Czech Republic, was divided into three different pa rts: (1) A new control strategy based on the gain scheduling method for the pressure control and the feedforward method for the level control has been proposed for stabilization of the desalter tank. (2) A special ratio contr oller connected in cascade to the original flow controllers has been used f or the minimization of the temperature difference between the heated stream s (not controlled in the original system). (3) A combined feedforward-feedb ack cascade system has been designed for the feed temperature control. All proposed systems have been tested and set in operation. it has been proven that there is outstanding improvement over the original control system in s tabilization of the output temperature, in simplification of the system ope rability, and in savings of heating medium.