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Experimental study and SEM-EDS analysis of agglomerates from gasification of biomass in fluidized beds

Abstract

Fluidized bed gasification is an attractive conversion technology for biomass. However, processing biomass in fluidized beds suffers from ash related problems. In this work, bed agglomeration of wood pellets and grass pellets was compared, focusing on de-fluidization temperatures and variation in microstructure and composition of agglomerates. The results showed that both biomasses form agglomerates at temperatures between 700 °C and 900 °C. After each test run, residual sand and agglomerates were discharged and the ash/bed material ratio was calculated. Larger amount of accumulated ash and agglomerates were collected from the gasification of grass pellets than that from wood pellets, indicating that different mechanisms are present in the agglomerate formation. The ash/bed material varied from 3 to 10 wt% for the grass pellets and from 0.8 to 1.5 wt% for the wood pellets. A scanning electron microscope with energy dispersive X-ray spectroscopy was used for characterizing morphology and elemental composition of the agglomerates. The findings show that the surface of agglomerates from grass were dominated by Si, Ca and K, while the surface of agglomerates from wood mainly were dominated by Si and K. The cross-sectional analysis concluded that Si, Ca, and K are the ash forming elements that play the most significant role in agglomeration processes.

Category

Academic article

Language

English

Author(s)

  • Nora Cecilie Ivarsdatter Furuvik
  • Liang Wang
  • Rajan Jaiswal
  • Rajan Kumar Thapa
  • Marianne Sørflaten Eikeland
  • Britt Margrethe Emilie Moldestad

Affiliation

  • University of South-Eastern Norway
  • SINTEF Energy Research / Termisk energi

Year

2022

Published in

Energy

ISSN

0360-5442

Publisher

Pergamon Press

Volume

252

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