Oxy-combustion power plant integration in an oil refinery to reduce CO2 emissions

The refining sector comprises a lot of different processes, since a wide range of final products are obtained in refineries. In any case, CO2 emissions levels are high and three units can be considered as the main sources accounting the majority of carbon dioxide emissions to the atmosphere: the utility boilers system, the process heaters and the fluid catalytic cracking unit (FCC). In this study, the substitution of the utility boilers system for an oxy-combustion power plant is presented. The power plant is designed to cover the steam thermal and electricity demands of oil refinery. In addition, a heat integration methodology based on pinch analysis is applied to the whole concept for increasing efficiency. Final results show that more than 380,000 tonnes of CO2 could be avoided. Afterwards, a complete economic approach is carried out. Although profitability is still low with current economic costs, it is expected that in the medium term, oxy-combustion could be economically feasible in refining sector. To this extent, sensitivity analysis shows affordable values for main economic parameters that can be reached in the next years. A 24 €/MWh natural gas price reduces operational cost for oxy-combustion power plant below the conventional refinery value. An electricity price higher than 67 €/MWh and a CO2 cost around 20 €/tCO2 also seem to reduce operational cost below reference case ones. The study concludes with the analysis of some realistic future scenarios that prove the oxy-combustion technology both technically and economically feasible and payback periods between 9 and 11 years with IRR values around 7% can be affordable within the following years.