Title:
Char Conversion Characterized by Synchrotron Based X-ray Micro-Tomography and SEM-EDS Analysis
Author(s):
Strandberg, A., Thyrel, M., Rudolfsson, M., Lestander, T.A., Backman, R., Skoglund, N., Broström, M.
Document(s):
Paper
Abstract:
Fuel and ash properties were studied during fuel conversion by careful examination of char samples at different degrees of char oxidation. Two types of lignocellulosic pellets with different compositions of ash forming elements were used: poplar and straw from wheat. The charred pellets were investigated by synchrotron-based X-ray micro-tomography to create 3D images of the development of cracks, internal cavities, and ash layers during conversion. Furthermore, SEM-EDS was used to for detailed chemical and morphological information of the ash layers formed. The pore development during pellet conversion was found to deviate from what has previously been described for the structure of solid wood particles. Large cracks and internal cavities were formed extensively already during devolatilization. For poplar, no mobility of the ash forming elements were observed as the burnout proceeded. Ash layer properties varied between the two fuels: poplar formed a porous, permeable, low density and Ca rich ash, whereas wheat straw ash accumulated on the surface in the form of high density melt that develop into bubbles on the surface. As the conversion proceeded, the ash layer covered more of the active char surface area, but without totally blocking the gas transport.
Keywords:
pellet, poplar, thermochemical conversion, wheat straw, chemical composition
Topic:
Biomass Conversion Technologies for Heating, Cooling and Electricity
Subtopic:
Gasification for synthesis gas production
Event:
25th European Biomass Conference and Exhibition
Session:
2BO.14.5
Pages:
485 - 491
ISBN:
978-88-89407-17-2
Paper DOI:
10.5071/25thEUBCE2017-2BO.14.5
Price:
FREE
