Industrial process control system due to integration of equipment, existing material and energy recycle streams and their effects are extraordinary importance. The process in terms of safety, product quality and control stability have a challenge when there was defects in a process control system. The isomerization process is gaining importance in the presence of refining context due to upgrading the octane number of light naphtha fractions and also simultaneously reduces aromatic compounds especially benzene content. In this study, the isomerization unit control system of Imam Khomeini Oil Refinery Company (IKORC, shazand, Iran), by defined four controllers include: the temperature controller on pre-heater exchanger, the concentration controller on depentanizer, deisopentanizer and deisohexanizer towers. This work is based on the nine principles of the plant-wide process control, was investigated. It should be noted that currently lack these four controllers in isomerization unit, confront this unit to challenge in dealing with sudden disturbances. The results show that obtained data from dynamic simulation by Aspen Hysys v7.3 had an acceptable compliance with the principles of plantwide process control theory.
