Abstract: During the actual production of cracking furnace in the ethylene plant at PetroChina Sichuan Petrochemical Co., Ltd., the process and control were inconsistent with the expectations. The load of the gas phase cracking furnace was too high, so through the transformation of fresh propane process, part of the propane was sent to light hydrocarbon furnace for cracking, so as to ensure the stable load of gas phase cracking furnace. The purge gas system was pressurized, so a secondary line was added to the electromagnetic valve which controls the return of purge gas to the hearth of cracking furnace, and the drain pipeline of the purge gas system was led to the coke pool for the formation of a backwater bend, so as to meet the safety and environmental requirements on site. The temperature of super high pressure steam was greatly fluctuated due to the unstable flow of attemperating and pressure reducing water, so the split control of the attemperating and pressure reducing water was optimized, and the linear unstable valve was limited, so as to ensure the stability of the process parameters of super high pressure steam. And the limit method is also used to optimize the split control of fuel gas flow, so as to ensure the stability of fuel gas flow.

Key words: gas phase cracking furnace, purge gas, super high pressure steam, fuel gas