ASH CHARACTERIZATION, TRANSFORMATION AND DEPOSITION IN BIOMASS-FIRED MOVING GRATE BOILERS

Abstract

To better reveal the ash deposition, mineral transformation, microstructure heterogeneity and mineral texture evolution behavior during combustion, several biomass fuels and combustion by-products were collected from different locations in two biomass-fired moving grate boilers. The elemental distribution, mineralogy, morphology and chemistry of fuels and combustion by-products were determined by different analytical techniques. Synchrotron radiation XRD and Rietveld refinement method were applied to determine the mineralogy, refine the crystallographic structures of minerals, and characterize texture heterogeneity of minerals in ash deposits. The procedures of SRXRD data reduction, Rietveld phase identification and texture analysis of ash deposits were summarized and developed, which will provide a new way to investigate and understand the ash deposition behavior in the boilers. The phase transformation pathways between different minerals during combustion were proposed. These findings will provide a deep insight into the ash deposition behavior, mineral transformation and mineral texture evolution during combustion in grate boilers.