Modeling A Commercial Hydrocracker And Molecular Reconstruction Of Petroleum Fractions

Hydrocracking of heavy petroleum fractions is an important route in refinery and petrochemical industries.Optimization of commercial hydrocrackers with the aid of mathematical model can greatly benefit related enterprises.To this end,this dissertation consists mainly of two parts,i.e.,modeling a commercial hydrocracker and molecular reconstruction of petroleum fractions.First,based on a discrete kinetic lumping model,a mathematical model was developed to describe the commercial vacuum gas oil(VGO)hydrocracker in the Sinopec Qingdao refinery and chemical company.The results showed that the hydrocracker mathematical model was able to simulate the product fractions(gas,naphtha,aviation kerosene and unconverted oil)and bed temperature distribution of the hydrocracker.In addition,the model was employed to study the effects of feedstock flowrate,hydrogen makeup and inlet temperature on the hydrocracking of VGO.Unfortunately,however,the above model can only predict a product composition in terms of fractions,rather than detailed molecular composition.Therefore,the second part of this dissertation was focused on the molecular construction of VGO.A stochastic molecular construction model,based on probability distribution function to depict the molecular structure of hydrocarbons,was developed to simulate Saudi Arabia middle crude VGO and Iran crude VGO.It was shown that the molecular mixture derived from the stochastic molecular construction model had similar properties(density,elemental composition and family composition)to the measured counterparts,indicating the reliability and accuracy of the model.Thus,the stochastic molecular construction model can be extended to the molecular-level kinetic modeling of VGO hydrocracking.