Abstract: Oil refining enterprises urgently need to reduce CO₂ emissions to meet the requirement of the “carbon peak and carbon neutral targets”. Decarbonization measures maintain current operating conditions unsurely result in loss of benefits. By using overall process optimization, the pathway of the Decarbonization measures with least environmentally expensive can be found out. For a typical 10 Mt/a refinery, the overall process model was integrated with the carbon emission model. The quality stream, energy stream and carbon stream in the whole plant were optimized synergistically, and the effects of selected Decarbonization measures were quantified and evaluated.The results show that measuresincluding optimizing the processing direction of material and gradient utilization of hydrogen are effective for reducing CO₂ emission and comprehensive energy consumption. Among them, in terms of processing direction of material, shortening the processing flow of hydrogen-containing gas and heavy oil is recommended as a priority. For gradient utilization of hydrogen, each ton of reformer hydrogen utilized in this case could reduce 0.51 tons of carbon emission for the refinery. The present work provides guidance for refineries to reduce CO₂ emission by optimizing the overall process.

Key words: CO₂ emission reduction, overall process optimization, quantitative evaluation, processing direction of material, hydrogen gradient utilization