(203c) Conversion of Solid Fuels in the Iron-Based Chemical Looping Process

The chemical looping schemes that directly convert solid fuels such as coal and biomass pose economical and technical attractiveness since it adapts relatively cheap solid fuels, avoiding a capital and energy intensive gasifier. For the solid fuel chemical looping processes to be feasible, the slow kinetics of solid-solid reaction between the solid fuels and oxygen carriers must be overcome. In addition, the effects of contaminants in solid fuels on the oxygen carriers need to be addressed. A two-stage counter-current moving bed is proposed for effective conversion of solid fuels. In the first stage, the oxygen carriers in the upper section convert the gaseous volatiles from the solid fuels. Then, the bottom stage converts char, as the metal oxides are reduced to the lower oxidation states. Prior to the moving bed demonstration, externally-heated fixed bed is used to simulate the reaction between volatiles and iron particles. Additionally, the char conversion enhancement is further studied with steam or CO2 along with the cold model study. These studies show that the oxygen carrier developed at the Ohio State University is capable of converting volatiles from coal and biomass and chars to CO2 with highly recyclable manner. The effects of contaminants such as sulfur and ash on the reactivity and recyclability of the oxygen carrier particle are also studied.