EFEITO DA TORREFAÇÃO DE PELLETS DE Pinus taeda L. NA PRODUÇÃO DE COMBUSTÍVEL COM MAIOR POTENCIAL ENERGÉTICO

Abstract

Pellets is a renewable granulated-solid fuel of high density based on biomass. Although the pellets have a higher concentration of biomass, their High Heating Value is not different from the biomass that gave rise to it. Because the low calorific value of the pellets is a limiting factor to its use as fuel, its possible to increase its energy content by the application of thermochemical processes via pyrolysis, such as torrefaction. The main purpose of this research is to verify whether the torrefaction of the pellets increases its calorific value and also evaluates its burning by means of the CO emission factor. The torrefaction occurred in the temperature range from 200 to 300ºC and in the time from 30 to 90 minutes. The main effects on energy content of the torrified pellets and environmental properties of its combustion were evaluated through linear regression modeling. Results showed that when we increased the severity of torrefaction, the gravimetric yield and the hygroscopicity of the pellets decreased. Additionally, when the fixed carbon increased, the high heating value also increased because the lignin content becames higher. Finally, in the incomplete combustion reaction, the air-fuel ratio and CO emission factor increased because of the carbon content was steadily higher. We conclude that the torrefaction process is efficient to increase the energy content of the torrified pellets, to reduce their hygroscopicity, and then to conducted for the production of high quality torrefied wood pellets. The implication is that torrefied pellets have a higher energy content and lower moisture content than biomass and it can contribute to the environment clearness purpose as a source of renewable energy.