Pilot-scale pyrolysis and activation of typical biomass chips in an interconnected dual fluidized bed: Comparison and analysis of products

A 150 kg/h novel pilot dual fluidized bed (DFB) was designed, constructed, and commissioned. In this study, six types of biomass chips were investigated and compared in interconnected pyrolysis and activation/gasification systems using dolomite as bed material, and employing steam and flue gas as activation agents. The maximum iodine and methylene blue adsorption capacities were 436.79 mg/g (pear wood char) and 203.65 mg/g (walnut wood char), respectively, indicating high adsorption capacity of char. The carbon fixation ratios were 34.70–53.75 wt%, and the maximum lower heating value of 9.34 MJ/Nm3 was achieved for pyrolysis gas with the highest CO and H2 contents of 44.30 vol% and 16.18 vol%, respectively. The maximum phenolic compounds reached 73.46% for mesquite wood chips oil. Oils collected from the riser contained fewer organic species compared to oil from pyrolyzer. Furthermore, energy efficiencies were found to range from 66.70% to 84.91%, and the total energy yields were 67.12–87.08%. The internal rate of return and payback period of the process were 33.25–44.29% and 3.0–2.2 years, respectively. Co-production of activated biochar, combustible gas, and oils from the interconnected DFB system exemplifies noteworthy environmental and economic advantages for sustainable energy practices.