Optimization of grading guard systems for trapping of particulates to prevent pressure drop buildup in gas oil hydrotreater

摘要

A new approach to optimize grading guard systems for gas oil hydrotreating reactor based on the phenomenon of clogging of catalyst beds with microparticulates and coke deposits was developed. Pellets with different shapes have been tested to obtain dynamic dependencies of filter coefficient and pressure drop buildup. The experiments were performed in the trickle-flow regime with different ensembles of microparticulates having sizes from 15 to 165 mu m. The observed effect of a filter cake formation was characterized in terms of average porosity of the interface beds and it was introduced in simulations plugging of catalyst bed. Estimation of the growth of coke deposits was made using modified Voorhies's equation and experimental samples obtained in the microreactor under hydrotreating process conditions using foulants of industrial gas oil hydrotreater. The analysis of coked samples was carried out using TGA. Based on the discrete model and experimental data, optimization procedure of grading guard systems was carried out using brute force search. All combinations of schemes of guard-beds were compared using integrated hydrodynamic resistance as a criterion. It was shown that an optimized scheme of guard-beds can reduce hydrodynamic resistance as compared to the schemes without guard-beds or with non-optimized guard-beds.