Long-term continuous operation of a 3-MWth chemical looping combustion system for steam generation and CO2 separation

This study demonstrates the long-term continuous operation of a 3-MW th natural-gas (NG)-fueled chemical looping combustion (CLC) steam generation system using a Ni-based oxygen carrier. The CLC system operated stably for more than 300 h and produced adequate heat to generate superheated steam. During long-term operation, the oxygen carrier maintained high reactivity and retained 88% (12.9 wt%) of its initial oxygen transfer capacity (14.7 wt%). At approximately 945 °C, the fuel reactor achieved a fuel conversion of 99.5% (negligible CH 4 and 0.5% H 2 ) and CO 2 selectivity of 96.6% (2.9% CO), resulting in the inherent separation of a high-concentration CO 2 stream (96.6%). Excess heat was successfully recovered through a boiler system to produce superheated steam (35 barg and 440 °C) at a rate of 2677 kg/h (2.46-MW th ), corresponding to 97% of the designed steam energy (35.8 barg, 323 °C, 3000 kg/h, and 2.53-MW th ). This study presents the first successful demonstration of steam generation from an MW-scale NG-fueled CLC process without external heat supply. In addition, part of the separated CO 2 was supplied to an integrated compression, liquefaction, and storage system, producing 5.4 ton/day of liquefied CO 2 with 100% purity (with no traces of CO and O 2 ). • A 3-MW th NG-fueled CLC system successfully operated for over 300 h continuously. • Ni-based oxygen carrier retained 88% oxygen transfer capacity after long-term use. • Remarkable fuel conversion (99.5%) and CO 2 selectivity (96.6%) were achieved. • Steam generated during CLC operation without external heat supply. • CO 2 produced from CLC liquefied and stored.