Impact of Biomass Ash-Bauxite Bed Interactions on an Indirect Biomass Gasifier

Journal article, 2016

The influence of interactions between biomass ash and bauxite bed material on the performance of an indirect gasification system was investigated. With bauxite as the starting material, changes in gasification performance over time were assessed through measurements of gas composition, the amount of tar in the gas, cold gas efficiency, and carbon conversion. As the operation progressed and interactions with ash elements occurred, the bauxite showed increased activities for tar decomposition and carbon conversion. Additional experiments with solid samples that were extracted from the gasifier were performed in a laboratory-scale reactor and revealed the activity of the bauxite toward a water gas shift reaction as well as an increased ability to transport oxygen. Further analyses of the same solid samples showed that the bauxite had been enriched with ash elements; specifically, catalytically active alkali metals were detected in leachable form. In general, bauxite has been shown as an interesting material from a fuel conversion point of view. However, the effect on fuel conversion has been overshadowed by the high oxygen transport ability of bauxite.