Abstract:

During the operation of the domestic FCC unit with two-stage regenerator, the separation efficiency of the first and second stage cyclone separators of the second regenerator abruptly decreased. It appeared that the average particle size of the equilibrium catalyst and the fines from the third stage cyclone separator increased, the fine content of the equilibrium catalyst decreased, and the catalyst loss increased. In the course of the inspection of the unit, it showed that the joint of the ash hopper and cyclone leg of the second stage cyclone separator of the second regenerator was severely fouled, as well as the external wall of the first and second stage cyclone separators of the second regenerator, and the conical outlet of the third stage cyclone separator of the second regenerator. The results showed that the content of calcium sulfate in the fouling samples from the second stage cyclone separator internal wall and the external wall of the first and second stage cyclone separators exceeded 70%, while the fouling of the third stage cyclone separator and the blades of the flue gas turbine was mainly catalyst fine powders and metallic oxides. The oxygen-rich regeneration environment of the second regenerator, the revamp for capacity expansion leading to the increase of catalyst concentration in the dilute phase and the increase of the content of iron and calcium in crude oil may account for the accumulation of calcium sulfate.

Key words: FCC unit, the second regenerator, cyclone separator, calcium sulfate accumulation, fouling, blockage, electric desalting, low oxygen content

摘要：

国内某两段再生催化裂化装置，在运行过程中出现第二再生器一、二级旋风分离器(旋分)效率突然降低的问题，具体表现：平衡剂、三级旋分细粉平均粒径变大，平衡剂中细粉减少，催化剂跑损量增加；装置停工检修时发现，第二再生器二级旋分灰斗与料腿连接处结垢严重，第二再生器一、二级旋分外顶部也出现垢块、第二再生器三级旋分单管下料锥口结垢严重。垢物分析结果表明：第二再生器二旋分内及一、二级旋分外顶部垢块中硫酸钙质量分数超过70%,而三级旋分及烟机叶片上积垢主要为催化剂细粉和金属氧化物。该装置第二再生器富氧再生环境、扩能改造导致第二再生器稀相催化剂浓度增加及原料油中重金属铁、钙含量升高可能是造成硫酸钙大量积聚的原因。

关键词: 催化裂化装置, 第二再生器, 旋风分离器, 硫酸钙积聚, 结垢, 堵塞, 电脱盐, 低氧含量