(16f) Investigation of Mechanism of Chemical Looping Combustion of Coal Utilizing

Chemical looping combustion (CLC) is an emerging technology for clean energy production from fossil and renewable fuels. In CLC, an oxygen carrier (typically a metal oxide) is first oxidized with air. The hot metal oxide is then reduced in contact with a fuel in a second reactor, thus combusting the fuel. Finally, the reduced oxygen carrier is transferred back to the oxidizer. CLC thus allows for flame-less, NOx-free combustion without requiring expensive air separation. Most importantly, CLC produces sequestration-ready CO2-streams without significant energy penalty. A solid fuel such as coal is rarely used in CLC since the process with solid fuels faces many challenges. Few studies have been reported on the combustion of coal with oxygen carriers. Several mechanisms for the reaction of coal have been presented but the mechanism is not clearly understood. Research work focused in understanding the reaction mechanism of coal with oxygen carriers will be presented in this paper.

Thermo gravimetric studies and flow reactor studies were conducted with coal, coal char and carbon mixed with various metal oxide oxygen carriers in the presence of both nitrogen and carbon dioxide. X-ray diffraction studies and X-Ray photo electron studies were also conducted to understand the solid?solid interaction at various temperatures. Identification of reaction mechanisms and rate information obtained from these studies will be presented.