Influence of Different Additives on the Slagging of Corn Straw and Design of Compound Additives

摘要

Biomass is regarded as a desirable substitute for fossil fuel worldwide. However, serious slagging and corrosion occur during its combustion, hindering its application in large-scale energy production. In the present study, we aimed to investigate the effects of different additives, such as MgCO3, CaCO3, Al2O3 and MgCO3-CaCO3-Al2O3, on the slagging characteristics of corn straw (CS). Our data showed that the effect of single additives on sintering intensity index (SII) was ranked in an order as MgCO3 > CaCO3 > Al2O3, and such effect on softening temperature (ST) was ranked as Al2O3 > MgCO3 > CaCO3. The existence of SiO2, potassium salt and aluminum silicate in CS was the primary factor causing slagging due to the formation of low-melting eutectics. The blend of additives initiated the occurrence of MgO, Ca2SiO4, Ca2Al2SiO7, KAlSiO4 and other compounds with high melting point, which was favorable for slagging mitigation. Orthogonal design was applied to study the effects of compound additives on SII, K content in ash, combustion performance of CS and HCl emission, and an optimal combination of additives consisted of 2.0 wt.% MgCO3, 2.0 wt.% CaCO3 and 1.5 wt.% Al2O3.