Abstract: 8 Linde Pyracrack1-1 cracking furnaces are designed for the Megaton ethylene plant at PetroChina Dushanzi Petrochemical Company, each with an ethylene production capacity of 150 thousand tons per year. The ethylene plant has been operated for 8 years since its startup in September 2009. The fouling in convection section was serious, and the superheating temperature of super-high-pressure steam (SS) in light hydrocarbon cracking furnace was low. By increasing the excess air coefficient, the temperature of SS was only maintained at 465~485 ℃. The energy consumption of cracking furnace was increased, and the thermal efficiency was low. Although manual cleaning was performed and high frequency acoustic wave soot blower was installed, the process requirements could not be met, thus influencing the long term operation of the ethylene plant. The chemical cleaning of convection section effectively solved this problem, improved the thermal efficiency of cracking furnace and reduced the emission of exhaust gas.

Key words: cracking furnace；convection section, chemical cleaning, thermal efficiency