Adhesion strength of straw biomass ash: Effect of dolomite additive

A self-designed tester is used to study the ash adhesion strength of straw biomass and the effect of dolomite additive. TG-DSC, SEM-EDX, XRD and thermodynamic equilibrium are applied to analyze the thermal behaviors, mineral transformation and liquid phase formations of ash samples. The results indicate that the adhesion strength of rice straw ash appears at 600 °C, increases rapidly above 700 °C, and reaches 21.83 kPa at 1000 °C. The melting related to KCl causes the ash adhesion strength of rice straw at low temperature. The more viscous silicate melts result in a rapid rise in ash adhesion strength with increasing temperature. Dolomite additive can inhibit the melting of KCl and increase the appearance temperature of ash adhesion strength. Dolomite promotes the formation of high melting point minerals such as orthoclase, CaMgSi2O6, wollastonite, periclase and magnesium silicate in ash, reduces the liquid phase and controls the growth of ash adhesion strength. When the addition ratio is more than 5%, dolomite has a better inhibitory effect on the ash adhesion strength of straw. When 5% dolomite is added, the appearance temperature of ash adhesion strength increases by 200 °C, and the ash adhesion strength decreases by 58.54% at 1000 °C.