Analysis and Prediction of Corrosion of Refractory Materials by Potassium during Biomass Combustion-Thermodynamic Study

As a kind of renewable resource, biomass has been used more and more widely, but the potassium contained in biomass can cause corrosion of the refractory. For a better understanding of corrosion thermodynamic mechanisms, the five components of common refractory materials (magnesium chrome spinel MgO center dot Cr2O3, magnesium aluminum spinel MgO center dot Al2O3, Al2O3, MgO, and Cr2O3) with potassium salts (K2CO3, K2SO4, and KCl) under high-temperature were studied by using the FactSage (TM) 7.0 software. Thermodynamic calculation results indicate that MgO is the best corrosion resistance of the five components of refractory materials. Based on the obtained results, the corrosion experiments in the laboratory were carried out (muffle furnace or high-temperature tube furnace) for corrosion reaction of KCl and MgO. The chemical compositions of the corroded samples were analyzed by X-ray diffraction (XRD). Under laboratory conditions (600-1200 degrees C), no corrosion products have been observed in the high-temperature corrosion experiments. The result indicates that to prevent the corrosion processes, refractories should contain as much MgO as possible.