A five-lump coupled kinetic model for residue hydrodesulfurization in an ebullated bed based on hydrocracking model

Abstract

Extensive attention is usually paid to sulfur removal in the residue hydrodesulfurization (HDS) process, however, the sulfur transfer (sulfur compounds are cracked into the low molecular weight sulfur compounds) is always neglected. In order to solve above problems, a five-lump coupled kinetic model for residue HDS based on hydrocracking model was proposed. A residue hydrocracking model with an absolute average error of less than 5 % was established firstly. Then the correlation between hydrocarbon conversion and sulfur transfer was established and the kinetics of sulfur transfer was described by employing this correlation. Subsequently, a coupled model for residue HDS was developed and the results showed the heavier the components were, the greater the amount of sulfur transfer would be. Compared to the conventional HDS model, the coupled model could calculate sulfur transfer and sulfur removal synchronously. For example, for components with boiling point above 600 °C, 52.4 % sulfur was converted into the hydrogen sulfide and 22.4 % sulfur was transferred within 4 h at 400 °C. The developed coupled model could provide a deep insight into the understanding of residue HDS.