Studies on products resulting from thermal conversion of Nigerian petroleum residue to hydrocarbons

The thermal upgrading of petroleum residues to liquid fuels was studied at atmospheric pressure in a delayed coking reactor system. The intent of this work was to investigate the effects of process variables such as reaction temperature (200°C to 600°C), reaction time (0 to 120min), additive concentration loading, and additive-to-residue ratio on the amounts and quality of organic liquid product (OLP). The results obtained from the gas-liquid chromatographic analyses of the OLP revealed an upward trend of the conversion process and selectivity of the aromatic compounds with additive-to-residue ratio (ARR). This led to maximum yield of 37.2% achieved with ARR of 5 compared to 31% achieved with ordinary thermal conversion. The selectivity for aromatic hydrocarbons was maximal at 83.1 wt%, the selectivity towards aromatics and aliphatic hydrocarbons were highest for methanol-potassium hydroxide and methanol respectively. In all additive system cases, maximum OLP was produced at an optimum reaction temperature of 370°C in the delayed coking reactor and at higher residence time. The gaseous product consisted of carbon monoxide and carbon dioxide and C 1 - C 6 hydrocarbons, which amounted to about 20 to 30 wt% of liquid distillate. Judging by all the information obtained in this study, high temperature, high reaction time, and methanol-potassium hydroxide appear to be efficient process conditions for thermal conversion of petroleum refinery vacuum residue.