催化裂化反应深度的研究与应用

Study on Reaction Severity of Catalytic Cracking and Its Application

由于流化催化裂化(FCC)原料组成、产品收率、目的产品组成与性质均已发生巨大变化,原料转化率已不能准确地反映现代FCC的实际反应深度。在研究催化裂化一次反应和二次反应的基础上,把催化裂化反应分为3类:即分子数量增加但相对分子质量减小的化学反应、分子数量减少但相对分子质量增加的化学反应和分子数量与相对分子质量基本不变的化学反应。提出了催化裂化反应深度指数的定义和计算方法,并用其计算了6套大型工业FCC装置的反应深度指数。结果表明,反应深度指数涵盖了裂解反应、缩合反应和中间产物二次反应进行的程度,反应深度指数比原料转化率或重油转化率能更显著地衡量催化裂化反应深度的变化。

Feedstock conversion ratio cannot be used as the parameter to accurately reflect reaction severity of modern fluidized catalytic cracking(FCC)unit due to changes in feedstocks composition,product yield,products composition and their properties.Based on their primary and secondary reactions,catalytic cracking reactions can be classified into three different types by comparison of before and after reaction:number of molecules increases but relative molecular mass decreases,number of molecules decreases whereas relative molecular mass increases,and not many changes of both number of molecules and relative molecular mass.Definition and calculation methods for reaction depth index(RDI)of catalytic cracking were proposed,and RDI values of six large-scale commercial FCC units were calculated.Calculation results suggested that RDI is more capable to measure reaction severity for FCC unit than traditional conversion ratio or heavy oil conversion ratio,since the concept of RDI considered the contribution of all three secondary reaction severities,i.e.,intermediate products,decomposition and condensation reactions.