The theoretical basis of oil-coal co-processing and process optimization

Abstract

This paper first described known thermal decomposition and hydrocracking processes using heavy oil and coal as feedstock respectively, where the characteristic and structural difference between crude and coal were presented. Studies showed that though fundamental differences observed between heavy oil and coal based thermal decomposition processes,the principle of free radical chain reactions was shared, which was the theoretical basis of oil-coal co-processing. It was reported that aromatics up to three-ring was mostly found in the hydrocracked products from coal feed; whereas segments from long paraffinic chain or aliphatic substituents in polycyclic aromatic hydrocarbons were the major components of oil based hydrocracked products. It should be noted that asphaltene and gum in heavy oil could favor the formation of coke and lower light oil yield during oil-coal co-processing, and the selection of suitable coal species was also significant. Based on the discussions,a two-stage reactors design was proposed for the co-processing process.