Conversion of Coal in a Fluidized Bed Chemical Looping Combustion Reactor with and without Oxygen Uncoupling

Chemical looping combustion (CLC) is a carbon capture technology that involves circulating metal-based oxygen carrier particles between two reactors, where the metal is alternately oxidized by air and then reduced by fuel as the fuel combusts. In the variant of CLC known as chemical looping with oxygen uncoupling (CLOU), the oxygen carrier releases gaseous O 2 in the fuel reactor, allowing for a rapid reaction with solid fuels. This study focuses on improving the understanding of mechanisms responsible for carbon conversion of coal and coal char in a bench-scale fluidized bed reactor using oxygen carriers with and without oxygen uncoupling properties. Effects of coal particle size and temperature on the rate of carbon conversion are evaluated in order to quantify performance and to aid in design and modeling of large-scale fully circulating chemical looping systems. The data confirms that conversion with a copper-based CLOU carrier is faster and results in lower CO and CH 4 concentrations than the natural ore ilmenite, which does not have CLOU properties. However, with coal as fuel, the increase in the rate of char carbon conversion with CLOU is lower than that previously reported because of competition for oxygen by volatiles. Conversion is also faster with smaller particles but results in higher CO concentrations as small particles gasify and release volatiles more quickly.