Effects of biomass composition variations on gasification and combustion characteristics

The main aim of this study is to investigate, analyze and compare the gasification and combustion characteristics of different types of pelletized biomass (softwood, herbaceous biomass and agriculture residues) with different contents of cellulose, hemicelluloses and lignin and to obtain cleaner and more effective heat energy production. Kinetic study of the thermo-chemical conversion of biomass pellets includes complex measurements of the biomass weight loss rate at thermal decomposition of biomass and correlating variations of the flame temperature, heat production rates and composition of products with estimation of the correlations between the main characteristics of the pelletized biofuel, biomass weight loss rates, heat energy production and composition of the products. The analysis shows faster thermal decomposition and thermo-chemical conversion of softwood granules (spruce) with a higher heating value and carbon content determining a correlating increase of the heat production rate and the rate of CO₂ production with a higher average volume fraction of CO₂ in the products. The higher heating value of wheat straw lignin promotes higher heat energy production that predominately refers to the char conversion stage. The analysis of the correlation between the nitrogen content in biomass and the NO_x mass fraction in the products evidences that a higher content of nitrogen in biomass pellets leads to higher average and peak values of the mass fraction of NO_x emission.