(55e) Development of an Equation Oriented Model Applied to a Hydrodesulfurization (HDS) Process

The presence of impurities in refining units compromises the quality of its final products. For example, sulfur, nitrogen, oxygen and some metals when linked to organic compounds constitute the so-called oleolytic impurities. Among these, sulfur proves to be harmful because it is corrosive, increases the polarity of oils, changes the color and odor of final products, and is a contaminant to various catalysts in the refining process. Hydrotreating (HDT) remains one of the most effective processes in the removal of oleolytic impurities¹. The hydrodesulfurization (HDS) process consists of treating the contaminated oil charge with sulfur through a hydrogenation reaction in the presence of catalysts under controlled operating conditions. In general, this process occurs in trickle-bed reactors operating in one or more stages under high pressure. The concentration of sulfur in the oil and the quality of the associated desired final product will define the treatment intensity and influence the overall performance of the process². Therefore, a detailed phenomenological model in a process simulator is a useful tool to describe the hydrodesulfurization reactions and their particularities.

In this work, the implementation of an equation-oriented model of an HDS reactor will be presented. The first step corresponds to the development of a reaction kinetic block model to describe the hydrodesulfurization (HDS) process in the AVEVA SimCentral Simulation Platform. In its simulation structure, SimCentral allows total autonomy in the evaluation and development of new models, without a deep knowledge about computational programming. The HDS block is based on an already developed and validated phenomenological model^3,4 and has been implemented in SimCentral using the model writing functionality. The developed HDS block model will then be used as the base submodel for the second step that corresponds to a more detailed version of the HDT (Hydrotreating) trickle-bed reactor, where a set of typical reactions will be defined. The HDS developed model and the simulator block are validated using data from literature and from a large Latin America Refining Company.

References

¹ Swain, E. J. (2018) “US Refining Crude Slates Continue Towards Heavier Feeds, Higher Sulfur Contents”, Oil Gas Journal, 96, pp. 43-48;

² Ancheyta, J.; Alvarez, A.; Leyva, C. (2016) "Hydrotreating of Oil Fractions" in Zeynep Ilsen Önsan and Ahmet Kerim Avci (ed.). Multiphase Catalytic Reactors: Theory, Design, Manufacturing, and Applications, pp. 295-327;

³ Korsten, H.; Hoffmann, U. (1996) “Three Phase Reactor Model for Hydrotreating in Pilot Trickle Bed Reactors”, AIChE Journal, 42, pp. 1350-1360;

⁴ Tavernard, A.; Fernandes, T.; Bispo, H.; Brandão, A. Nicácio, J. (2020) “Three-Phase Trickle-Bed Reactor Model for Industrial Hydrotreating Processes” submitted to Fuel Processing Technology.