催化裂化装置再生器二级旋分料腿结垢原因分析

Reasons analysis of fouling on the second-stage cyclone separator feed legin the regenerator of a catalytic cracking unit

为查明某催化裂化装置再生器二级旋分料腿结垢原因,对垢样进行元素分析,结果表明金属元素在样品催化剂细粉中进行了富集。通过X射线衍射分析,证明催化剂细粉发生了熔融和黏结。再生器二级旋分料腿结垢的主要原因:金属元素的富集降低了催化剂分子筛晶相结构崩塌温度。当CO及少量携带焦炭颗粒的细粉在二级旋分持续燃烧时,由于二级旋分内烟气夹带固体粒子很少,热阱作用减弱,使烟气温度骤升,当温度达到甚至超过催化剂细粉熔融温度时,细粉晶体结构破坏变为液相,在高速离心作用下黏附在料腿顶部形成垢层。通过再生器超温次数与垢样“年轮”层数关系比对,证明二旋料腿结垢与富氧再生环境及烧焦不均出现尾燃有对应关系,而金属元素富集降低了催化剂细粉的熔融温度。针对结垢原因,提出了相应的改进措施和建议。

By analyzing the elemental composition of the scale sample,it is demonstrated that metal elements have been enriched in the catalyst powder.Through X-ray diffraction analysis,it has been proven that the catalyst powder has undergone melting and bonding.The main reason for the scaling of the second-stage cyclone separator feed leg in the regenerator is that the enrichment of metal elements reduces the collapse temperature of the catalyst molecular sieve crystal structure.When CO and a small amount of fine powder carrying coke particles continue to burn in the second-stage cyclone separation,due to the small amount of solid particles carried by the flue gas in the second-stage cyclone separation,the heat trap effect weakens,causing a sudden increase in flue gas temperature.When the temperature reaches or even exceeds the melting temperature of the catalyst fine powder,the crystal structure of the fine powder breaks down and becomes liquid phase.Under high-speed centrifugation,it adheres to the top of the feed leg to form a scale layer.By comparing the relationship between the number of overheating times in the regenerator and the number of layers in the scale sample,it is proven that the melting of catalyst fine powder is related to the oxygen-rich regeneration environment and uneven coke burning,while the enriched metal elements reduce the melting temperature of the catalyst.Corresponding improvement measures and suggestions have been proposed for the causes of scaling.