CFD-Process Co-Simulation Of Catalytic Cracking For Heavy Oil

Against the background that the amount of recoverable crude oil is gradually decreasing worldwide and the quality of crude oil tends to be heavy and inferior,while the market demand for low carbon olefins is increasing,a new process of coupling alkaline catalytic cracking for heavy oil was proposed to realize the graded high-value conversion of inferior heavy oil and can obtain high-yield light oils and low carbon olefins.In this work,the reactor and the reaction-separation system of this process were simulated by using computer simulation technology that can scale up and optimize the process,which provides the theoretical basis of industrial application of this process.In order to realize the industrial scale-up and the subsequent fractionation system modeling and calculation of heavy oil alkaline catalytic cracking,this work firstly established ten lumped kinetic reaction networks.Matlab programming software was used to obtain the kinetic parameter,pre-exponential factor and activation energy of each reaction.It provides data for the simulation and amplification of reactor and subsequent separation process.The reliability of the model was verified by comparing the numerical solution of the yield with the experimental values.Then,the Computational Fluid Dynamics(CFD)method,which can accurately describe the internal flow and reaction behavior of the reactor,was adopted to realize the reactor scaling up of the process,and the numerical simulation and prediction of the catalytic cracking process in the 2 million ton/year downer reactor were carried out.The dynamic data was imported into the simulation software for calculation,and the coupling of CFD flow and dynamics was realized.The effects of operational factors such as the catalyst to oil ratio,reaction temperature,reaction time and recycle ratio on the product distribution were simulated and investigated.Finally,Aspen Plus,a process simulation software that enables the simulation of reaction-separation systems,was coupled with the reduced order model established by CFD simulation results,and the reaction-separation system of heavy oil alkaline catalytic cracking process was modeled.This method realizes the combination of CFD and process,which can accurately and quickly simulate the catalytic cracking process and make up for the shortcomings of CFD simulation which can only simulate a single reactor and the long calculation time.The results demonstrate that the combined CFD/process simulation model can be used to obtain reliable product predictions in a short time(30 s).This simulation method fills the gap of CFD-process simulation in catalytic cracking unit and provides a new idea and method for rapid simulation and prediction of alkaline catalytic cracking of heavy oil.