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

摘要：

为了研究高铬砖在含磷高钠煤渣侵蚀下的蚀损机制,以某厂多元料浆气化炉筒身上部与拱顶交界处残砖为试样,采用扫描电镜结合能谱分析仪对残砖进行了显微结构和微区成分分析。用后残砖由反应层、脱锆渗透层、含锆渗透层组成。由于服役条件下含磷高钠煤渣对高铬砖的溶解能力较强,基质(Al-Cr)_ss固溶体和部分电熔氧化铬颗粒重结晶形成较为致密的(Mg-Al-Cr-Fe)_ss多元尖晶石固溶体,使高铬砖产生结构差异,容易造成裂纹,是导致高铬砖蚀损剥落的主要原因。煤渣中的磷酸盐能够促进含磷晶相/液相的析出,提高了渣的黏度,可减缓渣对高铬砖的渗透。

关键词: P₂O₅, Na₂O, 煤渣, 高铬砖, 侵蚀