Study on High-Temperature Ash Behavior Characteristics of Biomass

In contrast, wheat straw ash, with comparatively lower CaO (4.92%) and MgO (2.82%) contents, tended to generate low-melting-point potassium silicates under similar thermal conditions. At high temperatures, both corn and wheat straw ashes exhibited typical crystalline slag melting characteristics, with viscosity increasing linearly as the temperature decreased below a certain threshold. The abrupt viscosity increase in corn straw ash slag was primarily caused by the rapid nucleation and growth of silicate crystals during cooling.

Due to the “chemical dilution effect” caused by the high P2O5 content, KAlSiO4 persisted throughout the cooling process in wheat straw ash slag, which resulted in a generally higher viscosity and a sharp viscosity increase at the final stage of cooling. This study elucidated the mechanism by which the ash chemical composition, through determining high-temperature phase equilibrium and non-equilibrium kinetics, macroscopically influences the ash melting and flowing behaviors.

This research provided a theoretical foundation for further exploration of the high-temperature properties of biomass ash.