关键词: P₂O₅, Na₂O, 煤渣, 高铬砖, 侵蚀

Abstract:

In order to study the degradation mechanism of high chrome bricks in phosphorus containing high sodium coal slag,a residual brick in the junction of the upper cylindrical part and the dome part of a multi-component slurry gasifier of a plant was analyzed.The microstructure and micro zone phase composition of the residual brick were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).Post-mortem analysis of the residual brick shows three layers: a reaction layer,a zirconia depletion penetration layer and a zirconia containing penetration layer.Since phosphorus containing high sodium coal slag has strong dissolution to high chrome brick during service,(Al-Cr)_ss solid solution in the matrix and some fused Cr₂O₃ recrystallized particles form (Mg-Al-Cr-Fe)_ss spinel solid solution,introducing structural differences and cracking,which causes spalling.Phosphate in the coal slag can promote precipitation of phosphorus containing liquid/crystal phases,increase the slag viscosity and slow down the slag penetration.

Key words: phosphorus pentoxide, sodium monoxide, coal slag, high chrome bricks, corrosion