(686a) Investigation of Chemical Looping Combustion of Coal Utilizing Various Oxygen Carriers

Chemical looping combustion (CLC) is an emerging technology for clean energy production from fossil and renewable fuels. Chemical looping combustion (CLC) is a new flameless combustion technology that involves the use of a regenerable metal oxide as an oxygen carrier that transports oxygen from the air to the fuel. In this process, direct contact between fuel and air is avoided with high-purity CO2 produced from the combustion of fuel gas. A Solid fuel such as coal is rarely used in CLC since the process with solid fuels faces many challenges. However, if we address these challenges CLC would be a very economical way for utilization of coal. Research work on feasibility of utilizing oxygen carriers for coal combustion will be presented in this paper. Samples of coal mixed with bulk and supported metal oxides (NiO, Fe2O3, CuO, MnOx, Co2O3) were heated up to 1000 oC in a Thermo Gravimetric Analyzer equipped with a mass spectrometer. Three steps of weight losses were observed: the moisture loss at about 100 oC, coal partial pyrolysis at 400-500 oC, and coal-combustion at 600-1000 oC. The results strongly supported the feasibility of coal combustion utilizing oxygen carriers. Combustion rate appeared to be faster in the presence of CO2 than that with N2. Thermodynamic calculations to understand the interaction of ash with metal oxide carriers and data from bench scale flow reactor tests will also be presented.