Modeling residue hydroprocessing in a multi-fixed-bed reactor system Original Research Article

A three-phase heterogeneous plug-flow reactor model was developed to describe the behavior of residue hydroprocessing in a multi-fixed-bed reactor system. The model considers gas–liquid and liquid–solid mass-transfer phenomena and incorporates reactions such as hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodemetallization (HDM), hydrodeasphaltenization (HDAs) and hydrocracking (HCR) as well as hydrogen consumption. HDS reaction was described by Langmuir–Hinshelwood kinetics while the rest of the reactions were modeled with power law kinetics. To estimate kinetic parameters, experiments were carried out in a multi-reactor pilot plant loaded with a triple catalyst system under the following operating conditions: 380–420 °C temperature and 0.25–1.0 h−1 liquid hourly space velocity (LHSV), keeping constant hydrogen-to-oil (H2/oil) ratio at 891 std m3/m3 and pressure at 9.81 MPa. Model predictions showed good agreement with experimental data in the range of the studied operating conditions. The model was also applied for simulating an industrial scale residue hydroprocessing unit with multi-bed adiabatic reactors and hydrogen quenching.