Numerical Modelling and Simulation of Gas-Liquid Trickle Flow in Trickle Bed Reactor Using an Improved Phenomenological Model

Abstract

For the past many decades, fossil fuels remain the major sources to fulfil energy requirements worldwide. Crude oil is processed in oil-refineries where it is subjected to hydrotreating. The process of hydrotreating involves the passage of the gas-liquid mixture through catalyst-filled Trickle Bed Reactors (TBRs) which involves simultaneous reactions of hydrodesulphurization and hydrodenitrogenation. In order to determine the actual energy requirements and thereby increasing energy efficiency and reducing associated cost, it is essential to have good understanding of dynamics of three-phase flow in trickle bed reactors. Correct estimation of pressure drop across the reactor height and contact efficiency of the system at different gas/liquids at different flow rates play a major role in the design of energy efficient trickle bed reactors. In this work a new phenomenological pore scale hydrodynamic model is proposed to predict pressure drop and liquid holdup in uniform and steady gas-liquid flow in a trickle bed reactor. Numerical analysis of already existing hydrodynamic models was performed and by inclusion of liquid film tortuosity in the flow, pressure drop and liquid holdup were estimated using the newly proposed numerical model. The flow simulations were performed in commercial software FLUENT using a three-phase Eulerian model. The numerical model was based on a robust 1D geometry which resulted in reduction of computation time. The model was validated against experiments reported in the literature. The obtained computational were also compared with other available models and showed good prediction for pressure drop and liquid holdup.