There is a coking phenomenon in settlers of the 1. 4 Mt/a catalytic cracking unit in Chan-gqing Petrochemical Company,which restricts the unit for a long period operation. The analysis showed that the cyclone separator of the settler adopts a soft connection structure,leading to a leakage of oil and gas due to breathing effect. The long residence time of these oil and gas in settler is the fundamental cause of coking. In the technical transformation in 2016,the cyclone separator was changed from the soft connection to a direct connection,the second stage riser was canceled,and the mixed recycling oil and raw materials enter the first stage riser. The results showed that the settler is not longer coking,the op-eration elasticity is stronger,while no catalyst loss is observed when the pressure fluctuation of the di-rect connected settlers occurs,and the solid content in slurry meets the requirement. There is no oil and gas in the upper space of the settler and no obvious coking phenomenon. The yield of light oil increases 0. 61 percent points,gasoline octane number improves 0. 47,and the content of LPG increases 0. 54 per-cent points.%中国石油长庆石化公司1. 4 Mt/a 催化裂化装置自建成以来,一直存在沉降器结焦问题,制约装置长周期运行.该装置沉降器旋风分离器采用软连接结构,分析认为软连接结构处油气的呼吸效应造成油气逃逸后在沉降器停留时间过长,这是引起沉降器结焦的根本原因.在2016年技术改造中,将沉降器旋风分离器由软连接改为直连,取消二段回炼油提升管,回炼油及原料混合后进入一段提升管.改造结果表明:沉降器基本不结焦,旋风分离器直连操作弹性较大,沉降器压力波动时无催化剂跑损现象,油浆固含量合格;沉降器上部空间基本无油气滞留,未发生明显结焦现象;轻质油收率提高0. 61百分点,汽油辛烷值提高0. 47个单位,液化气丙烯体积分数上升0. 54百分点.
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