Investigation Of Numerical Model For Heavy Oil Fluidized Catalytic Pyrolysis On Riser Reactor

Fluidized catalytic pyrolysis is a typical technology for increasing production of lowcarbon olefins.Riser reactor is one of the main reactors used in fluid catalytic pyrolysis unit at present.Research shows that developing a reasonable reactor mathematical model is very essential for the design,operation and optimization of the reactor,it is helpful for understanding the reaction process,predicting the product distribution and optimizing the operating conditions.However,some published investigation often neglected the influence of non-uniform structure to establish a concise and easy solving model,which might result in discrepancy with the actual situation.A well-adapted reactor mathematical model should include both reaction kinetics model and the effect of transfer process on the reactions.Based on the above reasons,a one-dimensional riser reactor mathematical model for catalytic pyrolysis of heavy oil has been established by combining of the eleven-lump kinetic model and one-dimensional axial flow model.According to the selected one-dimensional axial flow model——particle entrainment model,the riser reactor was divided into two reaction zones: dilute phase and dense phase zones,and their effects on the reaction were investigated respectively.Meanwhile,the eleven-lump kinetic model was established with taking into account the reaction characteristics and mechanism of catalytic pyrolysis process,and the reaction network was consisted of 48 reactions,some important secondary reaction were also considered besides cracking reaction.The kinetic parameters was estimated from experimental data obtained on a pilot unit by the hybrid function of particle swarm optimization algorithm and interior-point algorithm through the sub-model method.The final results showed that the predicted yield of each component coincided well with the experimental results,the maximum mean absolute deviations and mean relative error of the main products yields were 0.95% and8.84% respectively,which also indicated the mathematical model have good predicting ability for the outlet parameters of the riser reactor.It can be used to predict the product distribution and properties at certain set operating conditions.In addition,it can be found that the change of each lumps' yields in the dense phase zone is much greater than in the dilute phase zone,that is,the reaction mainly occurs in the dense phase zone,and the influence of the dilute phase zone on the reaction is less.Finally,owing to the mathematical model was proposed on a small riser reactor of laboratory,it has much difference with industrial production units,further improvements and optimization are needed for practical use.