Ash Fusion Characteristics Under Complex Atmosphere in Coal Combustion Process

Focusing on the ash fusion characteristics under complex atmosphere during coal combustion, an atmosphere-controllable ash fusion characteristics test system was developed. The effects of reacting atmospheres on ash fusion characteristics were studied. Then, the ashes which were prepared at high temperature (1 100℃) under different atmosphere were analyzed by XRD(X-Ray Diffractioin) to determine the compounds. The results indicated that the ash fusion points remained unchanged in the transformation process of O₂ into CO₂. The ash fusion points declined significantly under the weak reducing atmosphere (φ(N₂): φ(CO):φ(CO₂)=80%:5%:15%). The variation of ash fusion point of high iron content coal was more obvious. The ash fusion points increased when the reducing atmosphere was enhanced. Under the weak reducing atmosphere, the ash fusion points were lowest because the Fe contained compounds were reduced to Fe²⁺ contained compounds with lower melting temperatures. However, the formed Fe²⁺contained compounds were further reduced to elemental iron, thus increasing the ash fusion point.