采用锐钛矿型二氧化钛对两种硫酸盐黑液半焦在860℃的温度下进行了直接苛化与水蒸气气化实验。结果表明:黑液半焦中的有机碳可在6 min内气化完毕,直接苛化反应也可在此时间内完成;气化所得气体的干基高位热值约10 MJ/m3;气化与直接苛化所得固体产物熔点高于900℃且粉末状态良好,主要成分为五钛酸钠,该产物水解后生成氢氧化钠和不易继续水解的三钛酸钠;回收的三钛酸钠继续用于直接苛化实验时,固体产物没有发生结块现象,可以循环利用;约占黑液总硫20%的硫以非还原态留存于气化残余固体中。
Steam gasification of kraft black liquor char was performed at 860℃ in a tube furnace with direct causticization using anatase titanium dioxide and recycled sodium tri-titanate.The organic carbon in the black liquor char could be completely gasified within 6 min,approximately equal to the complete conversion time of sodium carbonate in black liquor char to sodium penta-titanate at these conditions,and the generated dry gas had a high heating value of nearly 10MJ/m3.The main component of solid product was sodium penta-titanate,and the sodium tri-titanate recycled from hydrolysis of sodium penta-titanate had satisfactory reactivity compared to fresh titanium dioxide.No agglomeration of solid product was observed through the process of reactions.About 20% of total sulfur in black liquor retained in the gasified residual solid in the form of non-reduced state.