Interparticle desorption and re-adsorption of alkali and alkaline earth metallic species within a bed of pyrolyzing char from pulverized woody biomass

Pulverized pine sawdust was pyrolyzed at 500 degrees C for a period long enough to complete tar evolution, and the resultant char was subjected to further heating at 700 degrees C in a fixed-bed reactor. Net release of alkali and alkaline earth metallic (AAEM) species from the char as a fixed bed was negligible unless the He flow was forced to pass through the bed. Even when the forced He flow was applied, the net release of each AAEM species was significantly influenced by the bed height even within a range up to 2.3 mm. These results showed that volatile AAEM species underwent repeated desorption from the char surface and adsorption onto it within the bed.