Technical and life cycle performance comparison between petroleum coke chemical looping combustion and oxy-combustion combining with advanced steam cycles for power generation processes

Inferior petroleum coke is attractive to be used in power generation industry since it has the advantage of high calorific value. To address the environmental problem of petroleum coke combustion for power generation, this paper establishes a process model of petroleum coke chemical looping combustion (CLC) and compares its performance with that of a petroleum coke oxy-combustion (OCB). The results show that CO2 capture rate of the CLC and OCB both reach about 100%. Under the petroleum coke conversion rate of 70%, the net electrical efficiencies of the petroleum coke CLC and OCB are 28.61% and 24.68%. The life cycle energy consumption and GHG emission of the CLC and OCB are 12.08/12.76 GJ/MWh and 338.03/397.91 kg CO2 eq/MWh, respectively. Compared with the sub-critical steam cycle in the above base case, the net electrical efficiencies of the CLC integrated with supercritical and ultra-supercritical cycles are increased by 0.93 and 1.53 percentages points, while their life cycle energy consumption and GHG emission are decreased by 0.31/0.49 GJ/MWh and 5.85/ 10.34 kg CO2 eq/MWh. When the conversion rate increases from 70% to 95%, the net electrical efficiencies of the CLC process are increased to 39.71/40.97/41.84%, and their life cycle results are decreased to 9.32/9.09/8.95 GJ/MWh and 300.85/296.20/292.07 kg CO2 eq/MWh. Therefore, improving conversion rate of the CLC and its coupling with advanced steam cycles for power generation are important for clean and efficient utilization of inferior petroleum coke.