The physicochemical properties of different biomass ashes at different ashing temperature

There are no specific standards for biomass ash analysis in China, so the standards for coal ash analysis are usually used to determine the property of biomass ash. Three kinds of biomass including rice straw, pine sawdust and Chinese Parasol Tree leaf burned at 815 °C, 600 °C and 500 °C respectively corresponding to the temperature required in the standard of GB and ASTM. The ash content and composition were analyzed. Based on the ash composition results, the volatilization of alkali oxides in biomass ash and slagging/fouling problems related to biomass thermochemical conversion were investigated. The alkali metals were relatively more volatile with the increasing of ashing temperature. The crystalline phase composition and surface morphology characteristics of the ash particles were investigated by XRD and SEM analysis. The increasing ashing temperature resulted in the decreasing of the diffraction intensities of metal salts and the increasing of the diffraction intensities of silicon compound. Ash fusion temperatures were measured by 5E-AFII Ash Fusion Analyzer. The results indicated that the ash content, composition, crystalline phases composition, surface morphology and ash fusibility were all closely related to ashing temperatures. The analysis at 600 °C ashing temperature was regarded as the optimal for an exact determination of ash properties.