Study of the pyrolysis of biomass using thermo-gravimetric analysis (TGA) and concentration measurements of the evolved species

The mass losses of biomass and the mole fractions of evolved species during biomass pyrolysis were measured using a thermo-gravimetric analyzer and a real-time gas analyzer, respectively. Each biomass sample (sawdust) was pyrolyzed in a lab-scale furnace, in a nitrogen atmosphere under non-isothermal conditions at heating rates of 5, 10, 20, and 30°C/min until the furnace wall temperature reached 900 °C. Using a non-isothermal kinetic method based on a first-order model, the experimental data from the thermo-gravimetric analysis (TGA) and real-time gas analysis (GA) were interpreted using a single model and a parallel model, respectively. Using the TGA data, the activation energy (E) and pre-exponential factor (A) were 1451kJ/mol and 2.67E+111/min, respectively. Utilizing both the TGA and GA data, the calculated activation energies for CO, H_2{1} 11, H_2{2}, THC, and the liquids (tar+water) were 41.7, 39.6, 51.1, 37.6, and 128.4 kJ/mol, respectively. By subtracting the total gaseous mass from the DTG (derived thermogravimetric) data, the yield of the liquids was obtained and was found to be higher (58-64%) than the yields of the pyrolyzed gas (20-25%) or of the char (10-12%). The cold gas efficiency (CGE) ranged from 0.38 to 0.47.