Systems analysis of pressurized chemical looping combustion for SAGD applications

Chemical looping combustion is a promising option for the conversion of fossil fuels with inherent separation of CO2 and efficient use of energy. Nevertheless, key process challenges such as oxygen carrier reaction rates, costs, and environmental concerns still exist. We expected that these challenges would be overcome by operating chemical looping combustors at elevated pressures with ilmenite ore as the oxygen carrier. This work describes a design study that was performed to examine the potential for replacement of once-through steam generators (OTSGs) at steam assisted gravity drainage (SAGD) facilities for bitumen production with near zero CO2 emission pressurized chemical looping combustors. In order to minimize capital costs for the systems, design was constrained to ensure that all major components could be shop built. Heat and material balances for many different process configurations were generated using Aspen HYSYS process simulation software allowing for a range of options to be evaluated. We determined that operating pressures should be restricted to between 4 and 7 bar(g) to achieve very high steam generation efficiencies, while avoiding high power demand. Energy integration of pressurized chemical looping combustion with a Canada's Oil Sands Innovation Alliance (COSIA) typical SAGD plant using Pinch analysis was performed resulting in a significant decrease in natural gas and boiler feed water (BFW) make-up requirements, while at the same time reducing CO2 emissions by over 95% down to 2.85 kg CO2/bbl bitumen. Having established that process performance is attractive, an economic study to establish the most economical design for pressurized chemical looping combustion for steam generation is now required.