Some remarks on direct solid fuel combustion using chemical looping processes

Direct solid fuel combustion using the concept of chemical looping is a novel approach projected to have higher energy efficiency than conventional and competing technologies in a carbon-constrained scenario. The concept is first discussed by presenting a thermodynamic analysis on oxygen carrier material selection. Iron-based material is considered as a promising candidate, and its salient features in the context of solid fueled chemical looping combustion (CLC) are introduced. The CLC reactor configurations are compared based on the modes of reducer design and operation, which significantly affects the whole system performance. A brief review on recent experimental studies indicates that initial results for the solid fueled CLC technologies are promising. An optimal reducer configuration that provides effective gas-solid contacting pattern, and the need for favorable thermodynamics of the oxygen carrier medium were identified as the important challenges for an eventual chemical looping combustion with solid fuels commercial scale-demonstration.