Solar pyrolysis of beech wood: Effects of pyrolysis parameters on the product distribution and gas product composition

The solar pyrolysis of beech wood was investigated with the objective of determining the optimal pyrolysis parameters for maximizing the LHVs (lower heating values) of the gas products because they can be further utilized as fuel gas for power generation, heat and production of transportable fuels. The investigated variables were the pyrolysis temperature (600-2000 °C), heating rate (5-450 °C/s), argon flow rate (6-12 NL/min) and pressure (0.44-1.14 bar). The results indicate that the product yields (liquid, char and gas), gas composition (H2, CH4, CO, CO2 and C2H6) and LHV are strongly influenced by the pyrolysis parameters. The total gas LHV greatly increases with increasing temperature (from 600 to 1200 °C) and increasing heating rate (from 5 to 50 °C/s), which is mainly due to increases in the CO and H2 yields. The variation in the gas LHV with pressure and argon flow rate is slight. A maximum gas production of 62% with a LHV of 10 376 ± 218 (kJ/kg of wood) is obtained under solar pyrolysis conditions of 1200 °C, 50 °C/s, 0.85 bar and 12 NL/min. This heating value is almost identical to that of the initial beech wood, thus confirming that valuable combustible gases can be produced via the solar pyrolysis of beech wood.