PetroChina Liaoyang Petrochemical Company completed the modification of its ethylene plant for lighter raw materials in 2019 and transformed two gas furnaces to process liquefied gas and aromatic tail gas. The operation of the gas furnaces improved the ethylene yield, but the amount of circulating ethane increased greatly, resulting in the decrease of ethane conversion rate of the cracking furnace and affecting the normal operation of the plant. The secondary distribution of circulating ethane through process optimization solves the problem of low conversion rate. By reducing the outlet pressure of ethane vaporizer, the problem of high-frequency emission of ethane to flare due to high liquid level is reduced, and the system operation is optimized.