Exergy analysis and dynamic control of chemical looping combustion for power generation system

Chemical looping combustion (CLC) is an efficient technology for power generation system (PGS) and CO2 capture. Regarding carbon deposition, this work presents a global energy optimization strategy by integrating CLC with PGS process (CLC-PGS) based on exergy analysis. First, the CLC-PGS system is simulated by using Aspen Plus software and its steady-state simulation results are used for global exergy analysis. Second, the carbon deposition phenomena resulting in insufficient contact between oxygen carrier (OC) and methane (CH4) and thus low conversion of CH4 is considered in the CLC-PGS optimization. OC circulation rate is increased to address carbon deposition problem and alleviate exergy destruction along with fuel reactor (FR) temperature, the ratio of CH4 to steam (X-CTS), and the ratio of CH4 to OC (X-CTO) optimized simultaneously by exergy analysis. Finally, the pressure and liquid level of drum in heat recover steam generator (HRSG) are selected as key variables by transfer entropy method for control scheme design. The dynamic behaviors of three alternative control schemes are compared by Aspen Dynamics software, with the control scheme II resulting the best according to the stability indicators in the face of +/- 10% disturbances.