Reduced Pollutant Emissions and Slagging Rate of Straw Pellet Combustion by Optimizing the Multi-Layer Distribution of Secondary Air

The utilization of coal and other fossil fuels is becoming increasingly restricted. Straw biomass, as a clean and renewable energy, plays a significant role in achieving zero carbon emissions. However, straw biomass is prone to slagging in the combustion process due to its high alkali metal content. The ash slagging rate and pollutant emission level of flue gas can be reduced by optimizing the air distribution, in order to decrease the fuel layer temperature in the combustion chamber. The results reveal opposite change trends of CO and NO x concentrations in the flue gas. The NO x emissions of corn stalk combustion under the multi-layer secondary air distribution are obvious compared with those of rice husk combustion. The slagging rate of corn stalks is highly correlated with temperature T 1 of the fuel bed. The silica ratio ( G ), alkali / acid ratio ( B / A ), Na content index ( Na (index)) and alkaline index ( Al c ), cannot accurately predict the slagging tendency when temperature T 1 changes. Therefore, the modified predictive index ( G t ) was proposed to predict the slagging tendency of corn stalks with the combustion zone temperature T 1 effectively. The experimental results can contribute to the efficient combustion and low pollutant emissions of straw biomass