Modelling of high-chromia refractory spalling in slagging coal gasifiers

The economic viability of converting coal into clean burning liquid fuels in slagging coal gasifiers is compromised by the limited service lifetime of hot-face refractories. One of the most severe refractory degradation mechanisms is spalling, which can occur by either volume-expansion phenomena (compressive stresses) or by volume-shrinkage phenomena (tensile stresses). A volume-shrinkage model is benchmarked to high-chromia refractory material properties and performance under gasifier operating conditions. The model is found to be appropriate for first-order estimates of gasifier refractory lifetime when the apparent diffusivity of volatized Cr in the refractory includes the effects of slag-filled pores and cracks.