Investigation of biochar production process from pine shavings and nut shells and determination of optimum process parameters

The study aims to investigate the torrefaction of wood chips and nut shells and the identification of optimimum temperature and residence time parameters. Torrefaction is a thermal process with a temperature range between 200 °C-300 °C and residence time 10 to 60 minutes. As a result of this process, hydrophobic biochar with increased energy density and with high grindability, is obtained. This biochar can be used in a coal combustion system with coal or as fuel in gasification systems. Temperature, particle size, residence time, heat flow, biological properties of biomass are the parameters that affecting the process. In this study, torrefaction of pine shavings and nut shells which sent by TÜBİTAK MAM E.E. was carried out in a muffin furnace which has 0-1500 °C temperature range and 10 ° C/d heat flow. The experiments were carried out at 3 torrefaction temperatures (260 °C, 280 °C, 300 °C) with 30 and 60 minutes residence time for each temperature value. As the temperature and residence time increased, the mass yield and the volatile matter ratio decreased and the thermal value and the fixed carbon ratio increased for both feedstocks. The effect of temperature is greater than the effect of residence time. It was concluded that 300 °C and 60 minutes residence time processing conditions for wood chips and nut shells would be the most suitable production conditions for co-combustion of coal and biochar in the fluidized bed.