(480b) Copper Oxide-Based Oxygen Carrier for Chemical Looping Combustion of Methane: Investigation of Attrition Behaviors and Particulate Formation

Authors: 
Li, F., North Carolina State University
He, F., North Carolina State University
Linak, B., US EPA
Chemical looping combustion (CLC) process offers a potentially effective approach for CO2 capture from carbonaceous fuel combustion via cyclic redox reactions of oxygen carrier particles in circulating fluidized bed systems. A potential challenge to CLC is the attrition of oxygen carrier particles, which can result in loss of materials and/or particulate emissions. In this study, attrition behavior and particle loss of a copper oxide-based oxygen carrier from a methane CLC process was investigated in a fluidized bed reactor. The aerodynamic diameters of most elutriated particulates, after passing through a horizontal settling device, ranged from 2 to 5 μm. A notable number of submicron particulates were also identified. Cyclic reduction and oxidation reactions in CLC were determined to weaken the oxygen carrier particles, resulting in increased particulate emission rates when compared to oxygen carriers without redox reactions. The generation rate for particulates < 10 μm was found to decrease with progressive cycles over as-prepared oxygen carrier particles and then reach a steady state. The surface of the oxygen carrier is also found to be coarsened due to a Kirkendall effect, which also explains the enrichment of Cu on particle surfaces and in small particles. It is therefore desirable to collect and reprocess small particles generated from chemical looping processes to reduce the loss of Cu. The current study also indicates that particulate control devices based on existing technologies may be required for methane CLC using Cu-based oxygen carriers. The lifetime of the Cu-based oxygen carrier examined is estimated to be ~5000 h.