6-Lump Kinetic Model for a Commercial Vacuum Gas Oil Hydrocracker

Abstract

A 6-lump kinetic model, including a catalyst decay function for hydrocracking of vacuum gas oil in a commercial plant, is proposed. The model considers vacuum gas oil (VGO) and unconverted oil, having boiling point higher than 380-°C (380+°C) as one lump. Other lumps are diesel (260-380-°C), kerosene (150-260-°C), heavy naphtha (90-150-°C), light naphtha (40-90-°C) and gases (40-°C) as products. Initially, a kinetic network with thirty coefficients is considered, but following an evaluation using measured data and order of magnitude analysis, mainly the route passes of converting middle distillates to naphtha lumps are omitted; thus the number of kinetic coefficients is reduced to eighteen. This result is consistent with the reported characteristics of amorphous catalyst, which has the tendency to produce more distillates than naphtha. By using catalyst decay function in the kinetic model and replacing days on stream with a noble term, called accumulated feed, the prediction of the final approach during 1.5 years is in good agreement with the actual commercial data. The average absolute deviation (AAD%) of the model is less than 5% for all main products. If the residue or unconverted VGO is considered, the error only increases to 6.94% which is still acceptable for a commercial model. The results also confirm that the hydrocracking of VGO to upgraded products is represented better by a second order reaction.

Application of Bayesian Approach in the Parameter Estimation of Continuous Lumping Kinetic Model of Hydrocracking Process

“…For example, Sedighi et al [10] studied a 6-lump kinetic model by considering the vacuum gas oil (VGO) having TBP temperature greater than 380˚C, diesel (260˚C -380˚C), kerosene (150˚C -260˚C), heavy naphtha (90˚C -150˚C), light naphtha (40˚C -90˚C), and gases (<40˚C) as discrete lumps of the process. In the discrete lumps approach, the heavier products associated with a higher TBP temperature can partially convert to the lighter products in a parallel/series reaction chain while each reaction path has its own reaction kinetic rate.…”

Development of Vacuum Residue Hydrodesulphurization–Hydrocracking Models and Their Integration with Refinery Hydrogen Networks

“…Several authors have established the use of lumps in the kinetic modeling of VGO and heavy oil cracking systems . Recently, Gao et al proposed an eight-lump kinetic model for the catalytic cracking of vacuum residue fractions.…”

“…Several authors have established the use of lumps in the kinetic modeling of VGO and heavy oil cracking systems. 17 Recently, Gao et al 18 proposed an eight-lump kinetic model for the catalytic cracking of vacuum residue fractions. However, the model does not account for feedstock properties and thus makes it difficult to simulate the model outcomes on a different vacuum residue feed.…”

Analysis of Heat and Mass Transfer and Parametric Sensitivity in an Experimental Fixed-Bed Reactor for the Catalytic Cracking of Heavy Hydrocarbons Based on Modeling and Experiments

“…On the other hand, semiempirical models, which have simple calculations, cannot be used for these reactions. , Therefore, the lumping methodology has been utilized for the complex reaction systems involved in the catalytic cracking process. In this way, similar components according to their boiling point and molecular characteristics are categorized into several cuts or lumps. , Many lumping models for catalytic cracking have been proposed and classified into two groups: (1) components are lumped based on the molecular structure characteristics of hydrocarbons, such as the four-lump kinetic model of Ojong et al, the seven-lump kinetic model of Fukuyama and Terai, the eight-lump model of Wang et al., the twelve-lump model of Zong et al., and the seventeen-lump model of Singh et al; (2) components are lumped based on the boiling point or molecular weight range, such as the four-lump kinetic model of Dave et al, Ancheyta-Juárez et al, and by Shayegh et al, the five-lump kinetic model of Sánchez et al and Ancheyta-Juárez et al, , the six-lump model of Ancheyta and Sotelo, Sadighi et al, Xiong et al, John et al, and by Seyed Asaee et al, the seven-lump model of Heydari, and the eight-lump model of Sani et al, You et al, and Sun et al In addition to these two types, in several studies, lumped kinetic models based on the chemical structure and boiling points are mixed, such as the ten-lump kinetic model proposed by Du et al and the nine-lump model by Ebrahimi et al and by Zhang et al Generally, the type of model is selected based on the purpose of the research.…”