Syngas production from biomass pyrolysis in a continuous microwave assisted pyrolysis system

In light of the knowledge gap in the scale-up of microwave-assisted pyrolysis technology, this study developed a continuous microwave-assisted pyrolysis (CMAP) system and examined its feasibility for syngas production. Wood pellets were pyrolyzed in the system under various temperatures, and the product distribution and energy efficiency were investigated. At a processing temperature of 800 °C, the CMAP system obtained a high quality producer gas (lower heating value 18.0 MJ/Nm³ and a 67 vol% syngas content) at a yield of 72.2 wt% or 0.80 Nm³/kg d.a.f. wood, outperforming several conventional pyrolysis processes probably due to two factors: 1) reactions between primary tar and biochar enhanced by microwave irradiation, and 2) the absence of carrier gas in the process. Energy efficiency of the process was also assessed. Potentially the electricity consumption could be reduced from 7.2 MJ to 3.45 MJ per kg of wood, enabling net electricity production from the process.