A preliminary study of the dynamic behaviour of thermal cracking processes for implementing advanced control and optimization

Nowadays industrial chemical processes must operate at maximum efficiency and one of the ways to save energy and still obtain high quality products is by using advanced process control. The coking furnace is the heart of any thermal cracking installation and the coil outlet temperature influences directly the quality of the end products and the coke deposits on the walls. The major concern is to maintain a constant gas outlet temperature in order to decrease the deposits and implicitly maintain the tube metal temperature and the pressure, constant. Advanced control is a good alternative solution to obtain the desired product yield and still maintain the safety conditions, without changing the system's configuration or replacing the existent components with new ones. A mathematical model of a thermal cracking coil was developed, based on free radical mechanism and some basic assumptions. In order to predict the coil's behaviour (temperature, product yields and pressure), a simulator for the dynamic process was used.