Effect of main characteristics of pelletized renewable energy resources on combustion characteristics and heat energy production

With the aim to provide a more effective utilization of different renewable energy resources for cleaner and more effective heat energy production, this work presents a complex experimental research and comparison of the chemical composition and combustion characteristics for different types of pelletized biomass fuels. Biomass pellets are produced from wood biomass (spruce sawdust), herbaceous biomass (reed canary grass) and their binary mixtures under previously tested different pelletization regimes. The complex experimental investigation of the main parameters of biomass pellets and their combustion characteristics is carried out along with estimation of correlations between the combustion characteristics and the main characteristics of densified biomass samples. It has been found that the densification of herbaceous biomass with an addition of woody biomass (spruce sawdust) improves the combustion characteristics of the densified herbaceous biomass, providing a faster thermal decomposition of biomass pellets with the increase of the average mass loss rate from 0.125-0.130 g/s for densified reed canary grass to 0.142-0.144 g/s for the mixture of reed canary grass and woody spruce (50:50). The addition of woody biomass ensures a more complete combustion of volatiles and decreases the average mass fraction of polluting emissions (CO, NO_x) in the products. Moreover, the investigation results show that the densified biomass mixture of reed canary grass and spruce sawdust (50:50) has a lower ash content, a higher heating value, an increased heat production rate and total amount of energy in comparison with herbaceous biomass.