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Effective Diffusivity and Spalling Models for Slagging Coal Gasifiers
Author(s) -
Williford Ralph E.,
Johnson Kenneth I.,
Sundaram S. Kamakshi,
Pilli Siva
Publication year - 2008
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2008.02755.x
Subject(s) - spall , thermal diffusivity , materials science , slag (welding) , coal , composite material , porosity , refractory (planetary science) , ultimate tensile strength , metallurgy , diffusion , compressive strength , thermodynamics , chemistry , physics , organic chemistry
Spalling reduces the lifetime of hot‐face refractory linings in slagging coal gasifiers, and has an important impact on the economics of coal gasification. Spalling is caused by ingress of the molten slag into the porous refractory, followed by reaction with the refractory to produce either volumetric expansion (compressive stresses) or volumetric shrinkage (tensile stresses). In this paper, ingress of the molten slag into the porous refractory is described by an effective diffusivity that treats simultaneous capillary and diffusive mechanisms in terms of the average pore radius and the slag viscosity. This effective diffusivity can be applied in spalling models to estimate spall thicknesses that are useful for determining whether the spall originated from tensile or compressive mechanisms.