Upgrading of heavy oil and residuum by the CANMET hydrocracking process: comparison of pitch conversion from experiments using CSTR and tubular reactors

Abstract

A model was developed to derive rate of pitch (+524°c) conversion as a function of temperature in the CANMET hydrocracking process for upgrading heavy oils and refinery residues using gas-liquid-solid concurrent slurry reactors. The model considered the gas void fraction and degree of vaporization to be important pararneters. For the CSTR model, complete mixing in the liquid phase was assumed, whereas an axial dispersion model was used for tubular reactors. Rate constants can be derived from experimental data obtained from either continuous stirred tank reactor (CSTR) or tubular reactor experiments, or from both data simultaneously. Results for a single feedstock, light Arabian vacuum bottoms, are presented. Rate constants were derived solely from experimental results obtained from runs carried out in a CSTR. They were then used in an axial dispersion model to predict pitch conversions at conditions identical to those used in two tubular reactors with diameter/ length ratios of 102 and 48. Comparison of predictions with experimental results showeà very good agreement. The effect of vaporization on distributions of pitch conversion, pitch concentration and liquid velocity along the reactor was also examined.