Co-conversion of biomass and petroleum vacuum residue in delayed coker unit

Abstract

The co-conversion of rice straw biomass and petroleum vacuum residue is studied under the conditions of a commercial delayed coker unit. Co-conversion results in an increase in coke yield and decrease in pyrolysis oil yield as compared to the petroleum vacuum residue. The reduction of the acidity (TAN) of liquid product as compared to weighted average contribution from vacuum residue and biomass cracking is observed, making it suitable for processing in a refinery. Saturate compounds including paraffins and monocycloparaffins increase with increasing biomass dosing, whereas a decrease is observed for polycyclic aromatics. The amount of oxygenates in the liquid products increases with an increase in the biomass dosing. The sulfur content of coke from biomass co-processing is lower than the coke generated from vacuum residue alone, indicating a lower SO_x emission potential upon coke combustion. Metallic impurities concentrate in the coke / biochar produced during biomass co-processing, resulting in higher real density and ash content. The crystallite size of calcined coke decreases with an increase in biomass dosing but no substantial change in the graphite interlayer spacing occurs.