Exploratory Pilot-Scale Pyrolysis of Paulownia Wood Chips: Product Recovery and Operational Behavior

Pilot-scale pyrolysis requires joint assessment of product recovery and operational behavior. This exploratory study reanalyzed three Paulownia wood-chip runs at nominal setpoints of 300, 400 and 500 °C in a five-section reactor. Each condition processed a reported 20 kg wet-feed charge. Five-second timestamps defined a common 60 min window with 721 observations per run. Recovered solid masses were 7.3, 7.4 and 5.8 kg, and condensate masses were 9.1, 8.3 and 6.6 kg. Combined recoveries were 82.0, 78.5 and 62.0% of wet feed. Unadjusted gas-flow means were 1.757, 3.380 and 8.444 m3·h−1, conditional on an undocumented flowmeter reference state. Temperature-channel d10 means 302.94, 398.43 and 497.72 °C. Elemental analysis revealed a substantial enrichment of carbon content in biochar, increasing from 46.2 wt.% in raw Paulownia biomass to a maximum of 76.99 wt.% at 400 °C. Concurrently, organic dry matter content decreased with increasing temperature due to progressive devolatilizations and ash concentration. The findings confirm that Paulownia biomass can be efficiently valorized through pyrolysis into products suitable for renewable energy production, carbon sequestration and agricultural and environmental applications, supporting its integration into circular bioeconomy systems.