结焦对FCC反应路线压力分布的影响

某石化公司0.8 Mt/a催化裂化装置开工后反应路线压力分布逐渐偏离设计值,第45 d时各点压力达到最大值.检修时发现提升管油浆喷嘴上部和转油线水平段结焦严重,造成提升管和转油线内径分别减小1/3与1/2.结焦造成管线内径减小、油气线速增大,是压力分布增大的主要原因,反应压力升高主要受转油线结焦影响,Y型段压力升高受转油线和提升管结焦两方面的影响.高速油气和催化剂对焦层剪切能力增强是结焦厚度存在上限的主要原因.另外,装置运行45 d后压力维持小幅度波动,这是新焦层不断形成和旧焦层持续脱落造成的.

Effect of coking on pressure distribution of FCC reaction route

The pressure distribution of reaction route gradually deviates from the design value after the start-up of 0.8 MM TPY FCC unit in a petrochemical company,and reaches the maximum value on the 45th day.During the maintenance,seriously coking is found in the upper part of the slurry nozzle and horizontal section of the oil transfer line,resulting in the reduction of the inner diameter of riser and oil transfer line by 1/3 and 1/2 respectively.The main reason for increment of pressure distribution is the reduction of pipeline inner diameter and increase of oil gas velocity due to coking.The increase of reaction pressure is mainly affected by the coking of the oil transfer line,and the increase of the Y-section pressure is affected by the coking of the oil transfer line and riser.Coke layer thickness possess the upper limit,which is mainly due to the increase of coke layer shear capacity by the high speed oil gas and catalyst.In addition,the pressure fluctuates slightly after 45 days of operation,which is caused by the continuous formation of new coke layer and the continuous shedding of old coke layer.