Simulation of Heavy Oil Hydroprocessing

This chapter details the development of a hydroprocessing reactor model and its further application in the design and simulation of a heavy oil upgrading process developed by the Mexican Institute of Petroleum (IMP). The chapter includes a description of the case of study, the experimental studies, the mathematical formulation of the reactor model, reactor scale-up and design, and simulation results at different scales. 

Kinetic and reactor modeling will always be a fundamental step in the design of chemical processes. The main objective of this task is to construct a computational tool for predicting product distribution and reactor behavior at various operating conditions. In this sense, modeling of heavy oil hydroprocessing is of extreme complexity because there are so many parallel physical and chemical processes inside the reactor phase equilibrium, mass transfer of reactants and products between the three phases present in the reactor (gas, liqnid, and solid), intraparticle diffusion, a vast reaction network, and catalyst deactivation, to name a few. Ideally, the contribution of all these events must be accounted for in order to increase prediction capability however, the level of sophistication of the model will generally depend on the pursued objectives. 

Compared with the reactor model developed in Chapter 6 for hydrotreating of heavy-oil-derived gas oil, the reactor model for hydroprocessing of heavy oil must account for other phenomena that are implicit with the heaviness of the feed, such as 

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Alvarez A, Ancheyta J, Munoz JAD. Modeling, simulation and analysis of heavy oil hydroprocessing in fixed-bed reactors employing liquid quench streams. Appl. Catal. A Gen. 2009 361 1-12. 

A detailed model for steady-state and dynamic simulation of HDT reactor is developed. Heavy-oil-derived gas oil is used as feed to exemplify the solution of the model. Experiments were conducted at bench-scale reactor to determine kinetic constants of the different HDT reactions and related hydrodynamic parameters. The developed model is further applied to simulate the behavior of an isothermal HDT bench-scale reactor and nonisothermal HDT commercial reactor. The selection of heavy gas oil feed to model the HDT reactor was due to its ease in handling the experiments, analysis of products, and absence of catalyst deactivation at the conditions studied, so that the model can be properly applied and validated. The following chapters will focus on the adaptation and application of the model for modeling hydroprocessing of heavy oil. 

Chapter 8 is dedicated to the modeling of heavy oil upgrading via hydroprocessing. Experimental studies for generation of kinetic data, catalyst deactivation, and long-term stability test are explained. Mass and heat balance equations are provided for the reactor modeling for steady-state and dynamic behavior. Simulations of bench-scale reactor and commercial reactor for different situations are also reported. 

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