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Excluded / Included Mineral Matter and Its Size Distribution Relative Significance on Slagging and Fouling Characteristics

  • R. P. Gupta
  • X. He
  • R. Ramaprabhu
  • T. F. Wall
  • I. Kajigaya
  • S. Miyamae
  • Y. Tsumita

Abstract

The effect of the nature of mineral matter (extraneous or inherent) on combustion generated ash is investigated by means of thermodynamic calculations and combustion experiments in a drop-tube furnace. Five coals, including one high in silica, one high in calcium and magnesium and one high in iron, were analysed for mineral matter size distribution using the CCSEM technique. The particle size distribution of mineral matter is found to be bi-modal in nature. The coal samples are found to have included mineral matter smaller than 20 μm whereas the excluded mineral is mostly larger than 40 μm in size.

The nature of mineral matter determines its reactions during combustion; the excluded mineral matter is in equilibrium with the bulk flue gases at the gas temperatures whereas the included minerals are in equilibrium with char at the burning char particle temperature. It is predicted from the thermodynamic calculations that almost all the evaporation is either from the included mineral matter or from the atomically dispersed minerals in coal. This is due to the high temperature and reducing atmosphere inside the char particle. The release of the evaporated species is controlled by diffusion through the burning char particle and may be, therefore, estimated theoretically.

The theoretical predictions of the ash character so derived are compared with the experimental data obtained by firing the coals in 10%, 23% and 50% oxygen in a drop tube furnace. The amount of mineral matter that is vaporised may be related to fouling, whereas, the melt phase present on the surface of large particles may be related to slagging. The mineral matter distribution is, therefore, related its effect on these two factors.

Keywords

Particle Temperature Mineral Matter Mineral Species Included Mineral Coal Matrix 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1996

Authors and Affiliations

  • R. P. Gupta
    • 1
  • X. He
    • 1
  • R. Ramaprabhu
    • 1
  • T. F. Wall
    • 1
  • I. Kajigaya
    • 2
  • S. Miyamae
    • 2
  • Y. Tsumita
    • 2
  1. 1.Department of Chemical EngineeringUniversity of NewcastleAustralia
  2. 2.Ishijikawa-Harima Heavy Industries Co. LtdKoto-ku Tokyo 135Japan

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