环烷基蜡油加氢裂化装置反应系统压降升高原因

加工环烷基蜡油的中海石油宁波大榭石化有限公司2.1 Mt/a加氢裂化装置在运行过程中出现系统压降快速上升的情况，被迫停工。除了精制反应器压降外，系统压降主要发生在高压换热器部位。高压换热器入口分配器内部及精制反应器保护剂床层结垢篮及其上部积累了大量的白色垢物，堵塞了高压换热器入口分配器，导致高压换热器压降快速增大。该白色垢物为环四磷酸铁，是由装置进料中所含的铁元素与装置上游常减压蒸馏装置所添加的高温缓蚀剂中的含磷化合物反应所生成。提出控制进料中磷质量分数不超过0.5 μg/g，以及常减压蒸馏装置采用无磷缓蚀剂或升级设备材料等应对措施

REASONS OF PRESSURE DROP RISE IN REACTION SYSTEM OF NAPHTHENE-BASE VGO HYDROCRACKING UNIT

Due to the rapid rise of system pressure drop，the naphthene-base VGO hydrocracking unit with a capacity of 2.1 Mt/a of CNOOC Ningbo Daxie Petrochemical Co. Ltd. had to be shut down. It was confirmed that the system pressure drop occurred mainly in the high pressure heat exchanger and partially in the refining reactor. The white dirt accumulated in the inlet distributor of high pressure heat exchanger and also deposited in the scaling basket and in the upper part of the guard catalyst of refining reactor, resulting in a rapid rise of system pressure drop. The white dirt is Fe2P4O12 formed by the reaction of iron element in the VGO feed and the phosphorus compound in the high temperature corrosion inhibitor in the upstream crude distillation unit. Countermeasures, such as controlling phosphorus content in hydrocracking feed below 0.5 μg/g，meanwhile adopting the phosphorus-free corrosion inhibitor or upgrading equipment materials in the upstream crude distillation unit, were proposed.