催化裂化装置反应系统防结焦技术分析

叙述了催化裂化装置结焦的危害并指出油气重组分冷凝油滴是结焦的内因,油气所处的环境是结焦的外因。从焦块组成与焦块催化剂粒度分布可看出,焦炭中氢的质量分数不足4%,主要是催化剂细粉与高度缩合的碳氢化合物。在操作波动、沉降器温度变化时,很容易发生焦块脱落影响反应再生系统催化剂循环,从而导致非计划停工,影响长周期稳定运行。避免出现"未汽化油"和"湿"催化剂是防治反应系统结焦的有效手段,合理适度提高反应深度,降低反应器油气中油浆重馏分含量,也是减缓抑制结焦的重要手段之一。通过优化原料组成、采用MIP/MIP-CGP工艺和RICP工艺等新技术、优化粗旋设计和在粗旋灰斗增设预汽提器、优化提升管出口连接形式、操作上控制油浆不回炼并尽可能减少回炼油,规范开停工程序等有效防范和抑制结焦的措施,可以实现催化裂化装置长周期稳定运行。

Analysis of anti-coking technologies for reactor system in FCCU

The hazard of coking in FCCU equipment is described.It is pointed out that the condensed oil droplets formed by heavy components of reaction vapor is the internal cause of coking,while the reaction vapor’s surrounding condition is the external cause of coking.It is found out from the analysis of coke compositions and catalyst size distribution in coke that the hydrogen in coke is lower than 4 m% and the coke is mainly made of catalyst fins and highly condensed hydrocarbons.When the operation fluctuates and temperature in disengager changes,the coke block,affecting the catalyst circulation between reactor and regenerator,and the unscheduled shutdown of the unit is the final result.The effective measures to prevent the reactor system from coking is to eliminate ＂unvaporized oil＂ and ＂wet＂ catalyst.Properly increasing the reaction severity and decreasing the heavy distillation such as slurry oil in reaction vapor also proves to be an effective means for minimizing coking in equipment.The long-term smooth stable operation of FCC unit can be maintained by optimization of feedstocks,application of state-of-the-art technologies such as MIP/MIP-CGP and RICP,optimization of rough cyclone design,addition of pre-stripper for rough cyclone hopper,optimization of riser outlet connection,no slurry oil recycle and possibly minimizing recycle oil and practice of effective coking prevention and control measures such as standardization of start-up/shutdown procedures,etc.