Slagging characteristics of industrial waste incineration system in sections with different temperatures

Complex industrial wastes are prone to form slagging during the incineration process, causing blockage in the circulation parts of the incineration system and affecting the heat transfer, thus reducing the economy of the incinerator, and shortening its continuous operation cycle. The formation process and characteristics of slag in an incineration system were researched by X-ray diffraction, scanning electron microscope, energy spectrometer, and differential scanning calorimetry in this paper. The results show that the slag surfaces of samples in the high-temperature sections are in the molten state, which are mainly composed of low-melting-point eutectic compounds (NaAlSiO₄, NaAlSi₃O₈, CaMgSi₂O₆) and low-temperature eutectic compounds (CaAl₂Si₂O₈, Fe₂SiO₄). These low melting point eutectic compounds formed a molten state at high temperature, promoting the adhesion of slag particles to the incineration inner wall and sintering to create a dense slagging layer. The surfaces of slag samples in the low-temperature sections are characterized by particle agglomerates, with a decrease in sodium and calcium silicate/aluminosilicate content and the appearance of sodium and calcium sulfates in the slags. Gaseous sulfate and a small amount of silicate melt form a viscous layer to capture ash particles and promote slag growth at relatively lower temperature. Through kinetic calculations, the most probable mechanism function for the melting process of slag samples is f(α)=(1-α)².