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.