Abstract: The cracking properties of heavy feedstocks, such as hydrocracking tail oil, atmospheric second and third cut oils, vacuum distillation first and second cut oils were evaluated under the conditions of different temperatures with water to oil ratios of 0.8 in a small scale steam cracking simulation device. The results showed that with the increase of cracking temperature, the ethylene yield increased gradually, while the propylene yield decreased, the yields of diene and triene increased first and reached maximum at 810 ℃and then decreased. The hydrogenation tail oil had the highest yield of ethylene, propylene, and butadiene, indicating the best cracking performance, followed by the atmospheric second cut oil and the third cut oil, and the vacuum fractions (the first and second cut oil) were the worst.

Key words: ethylene, heavy distillate, cracking