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• Comprehensive study on fixed-bed decoupling gasifier was done using wood pellet. • Combustion zone is separated from other zones in the decoupling gasifier. • Syngas from decoupling gasifier had much higher CO 2 content (10–17%). • Tar yield of decoupling gasifier are 5.1 g/Nm3, 94% lower than updraft gasifier. • LHV of syngas from decoupling gasification was 6.82–7.66 MJ/m3. This study comprehensively assessed the gasification of wood pellets in a pilot-scale decoupling gasifier. Operating parameters, product characteristics, thermal degradation behavior as well as kinetic and thermodynamic parameters of the gasifier were evaluated and compared with conventional updraft gasifier. Temperature profiles showed that the decoupling gasifier temperatures in all zones were lower than in the updraft gasifier, even though the temperature of the combustion zone was the same. The tar yield from the decoupling gasifier was found to be 94% lower than that of the updraft gasifier. The LHV of syngas from decoupling gasification was 6.82–7.66 MJ/Nm3, which was lower than that from updraft gasification. Kinetics study suggested that the energy for the decomposition of wood pellet in the decoupling gasifier was slightly higher than that in the updraft gasifier, as proven by its higher activation energy. Thermodynamics analysis appeared to support that the presence of CO 2 in the flue gas atmosphere of decoupling gasification caused more heavy volatiles and char. This study is expected to deepen the understanding of the mechanism and overall characteristic of the fixed-bed decoupling gasifier for the production of low-tar syngas. [ABSTRACT FROM AUTHOR]

This paper aims to the design innovation concept of e-waste pyrolysis and decoupling biomass gasification in pilot-scale for e-waste recycling and metal recovery. The syngas product and exhaust gas from decoupling gasification were injected to the pyrolysis burner for fuel reduction in sustaining the pyrolysis process. Results showed that the PCB (printed circuit board) and WC (waste cable) materials had pyrolysis oil yield of 20% and 27.3%, respectively, and pyrolysis char yield of 48% and 42%wt, respectively. Single ring compounds were the major compositions of the pyrolysis oil. The main composition of the synthesis gas product was 10.91% vol (H 2), 23.4% vol (CO), and 5.68% vol (CH 4). The methane content of the decoupling process was higher than that of conventional gasification. Precious metal content in the PCB char comprised Au, Ag, and Cu. Metal recovery from PCB char and ash via ultrasonication was 83.8–89.8%. The combined pyrolysis and decoupling gasification process offered a reduction in LPG (liquefied petroleum gas) consumption (36.1–41.7%), and high energy recovery from the pyrolysis products (53.4–81.6%). This could save the cost of e-waste recycling by about 25.7–28.7% compared to traditional pyrolysis. Therefore, the combined pyrolysis and decoupling gasification has a very good potential for e-waste conversion and metal recovery. [Display omitted] • E-waste pyrolysis and decoupling biomass gasification were investigated. • Characteristic of pyrolysis oil from PCB and WC was middle distillate. • Metal recovery was 83.8% (PCB char) and 89.8% (PCB ash) using ultrasonication • Reduction in LPG consumption was 36.1-41.7% and energy recovery was 53.4-81.6% • E-waste conversion cost was 0.19-0.2 USD/kg. [ABSTRACT FROM AUTHOR]