Abstract: The conventional control strategy adopted for the cracking furnace of the 800kt/a ethylene plant at PetroChina Sichuan Petrochemical Co., Ltd. led to some problems including a large fluctuation in average COT, the imbalance of pass temperature and the unstable control of total feed flow. Advanced process control (APC) system was designed for the eight USC tubular reactors, including total feed volume and pass temperature balance control and average COT control. The background and practical needs for the APC system and the system struction, operation interface and securable logic of advanced control are introduced. The application results show that, compared with the conventional control strategy, the APC system has better tracking ability, robustness and disturbance rejection ability, and shows high value in industrial application.

Key words: cracking furnace；advanced process control, coil outlet temperature/COT, securable Logic