煤催化气化工艺中碱金属腐蚀刚玉质耐火材料的实验研究

针对煤催化气化反应器设计中遇到的材料问题,采用碳酸钾及催化气化工况富含碱金属气化灰渣为实验原料,进行了碱金属腐蚀刚玉质耐火材料的实验研究。着重考察了有氧空气气氛和无氧还原性气氛、反应温度、反应时间、碱金属存在形态对腐蚀行为的影响,并结合SEM-EDX、XRD、核磁Al谱等表征手段,研究了反应前后碱金属和刚玉质耐火材料的成分、物相及结构变化。结果表明,碱金属对耐火材料腐蚀行为受反应的温度、气氛、时间及碱金属存在形态等因素影响较大。分析表明,有氧空气气氛下腐蚀尤为严重的原因是,原料中存在的钾与刚玉耐火材料发生化学反应生成新的钾的铝酸盐物相,且其含量随温度升高、反应时间延长而增加。

Experimental research on corrosions of corundum refractory by alkali metals in catalytic coal gasification process

The research on the issue of material corrosion in catalytic coal gasifier was focused on, in which the potassium carbonate and the coal ash from catalytic coal gasification with high alkali content were used to test the corrosion to the corundum refractory. The corundum refractory corroded by alkali metals at different reaction atmospheres, temperatures, reaction time, and alkali metal forms was characterized by using scanning electron microscope and energy spectrum analysis(SEM-EDX), X-ray diffraction (XRD) analysis, and ²⁷Al nuclear magnetic resonance (NMR) analysis. The results show that the corrosive behavior of alkali metals on refractory is affected by temperature, reaction atmosphere, reaction time, and alkali metal forms. Specially, the more serious corrosion of corundum refractory in air takes place due to a new phase, potassium aluminate, being formed via chemical reaction between potassium carbonate or coal ash with high alkali content and corundum refractory, and the content of potassium aluminate increases with increasing temperature and reaction time.