Simulation of an Atmospheric Residue Desulfurization Unit by Quasi-Steady State Modeling

Abstract

The current trend in petroleum refining is to maximize the conversion of the bottom of the barrel to improve the profitability of the refinery. Atmospheric residue desulfurization (ARDS) plays a key role in this, especially, when processing crudes with moderate to high sulfur contents. A deterministic quasi‐steady state model has been developed to simulate the long term behavior of the reaction section of an atmospheric residue desulfurization (ARDS) unit, consisting of four co‐current catalytic trickle bed reactors in series. The model uses the properties of the feedstock and the catalyst and is capable of simulating profiles of sulfur, coke, and metal depositions and the temperature along the reactors, taking into account also catalyst deactivation. Hydrogen quenching has also been simulated and simulation results predict all the essentials of the long term behavior of both experimental and industrial scale ARDS reactors satisfactorily. Comparing the simulation results with actual commercial data, the model predicted perfectly the middle part of the run. The model is unable to simulate the End‐of‐Run conditions due to pore mouth plugging phenomenon.

Evaluation of Time-on-Stream Deactivation Models with Effectiveness Factors for Industrial Feedstock Hydrotreating in Bench-Scale Tests

“…Each form was described by its own reactivity and complex reaction modes. In this study, the compounds were grouped according to their species – sulfur for HDS reactions and nitrogen for HDN reactions – to express the chemical reaction rate into a single reaction model. , …”

“…In this study, the compounds were grouped according to their species − sulfur for HDS reactions and nitrogen for HDN reactions − to express the chemical reaction rate into a single reaction model. 61,62 To study the reactions on the internal surface area of the catalysts, we defined the reaction rate (r j ″) based on per unit of surface area (mol/(m 2 s)) (r j ″= r j ′/Sa), where r j ′ is the reaction rate based on per catalyst mass (mol/(g cat s)). Furthermore, the kinetic model to describe the HDS reaction was based on a Langmuir−Hinshelwood model (eq 12) with hydrogen sulfide inhibition, while for the HDN reaction, the rate was expressed by the power-law model (eq 13) with respect to the concentrations of nitrogen and hydrogen.…”

Optimization Study of Residuum Hydrotreating Processes

“…For this reason, the mathematical model can be considered as a quasi-steady state model describing the ARD process at different time snapshots. Detailed description of the mathematical model used in this study is presented by Al-Radwan (1996) and Lababidi et al (1998).…”

“…Chao et al (1991) developed a mathematical model describing the catalyst deactivation in commercial-scale hydrodesulfurization reactors. Lababidi et al (1998) presented a deterministic quasisteady state model to simulate the long-term behaviour of the reaction section of an ARD unit. Reviews of catalytic hydrotreating and conversion of residues were presented by Dautzenberg and Deken (1984), and Baltus (1993).…”