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This study designed and fabricated a novel top-lit downdraft gasifier stove (TLDDGS), which was compared with a traditional top-lit updraft gasifier stove (TLUDGS) in terms of modeling and performance. The experimental and simulation results demonstrated that the novel TLDDGS exhibits a downward-flow configuration. The average fuel consumption measured in the experiments was 4.57 ± 0.933 g/min. The average flame temperature from the experiment was 608 ± 43 °C. The TLDDGS mean flame temperature remained stable throughout the experiment. The O 2 , H 2 , CO 2 , CO, CH 4 , and N 2 in the diluted syngas from the experiment were 16.07, 0.33, 0.66, 2.56, 0.34, and 80.04% by volume, respectively. The total suspended particulates and CO in TLDDGS and TLUDGS were 15 and 28 mg/m3 and 335 and 69 ppm, respectively, which are within the limits specified by the local standard. Thus, the developed TLDDGS is a promising alternative for sophisticated cooking applications because of its superior performance in terms of flame stability. • The new design of top-lit downdraft gasifier stove has a partial syngas downward flow direction. • The top-lit downdraft gasifier stove has superior flame stability than the conventional stove. • The top-lit downdraft gasifier stove has less total suspended particulates than the conventional stove. • The top-lit downdraft gasifier stove has emission performance according to the standard. • The simulation well explained the mechanism of the top-lit downdraft gasifier stove. [ABSTRACT FROM AUTHOR]

• 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]

[Display omitted] • An integration of pilot-scale HTC, gasification, and anaerobic digestion for EFB conversion was investigated. • Inherent AAEMs have significant effects on gasification products. • CO and H 2 were enhanced under CO 2 /O 2 gasification. • Liquid products from HTC can be utilized for methane production via anaerobic digestion. • The mass and energy balance revealed that the whole process could be feasible. In the context of evolving a circular economy for the palm-oil industry, this article presents a study of oil-palm empty fruit bunch (EFB) conversion and utilization within a palm-oil mill. Pilot-scale hydrothermal carbonization (HTC), washing and gasification processes, as well as anaerobic digestion of the HTC liquid product were investigated. Results showed that the fuel properties of hydrochars had improved. In terms of air gasification, char and tar products accounted for 22.7–33.8 % and 17.3–28.8 %, respectively while CO 2 /O 2 gasification resulted in 31.3–36.6 % for char and 8.5–30.8 % for tar. In general, hydrochar (HT-EFB) gave the lower tar content compared to washed hydrochar (HTW-EFB) due to the catalytic effects of alkali and alkaline earth metals. Major tar components from HT-EFB and HTW-EFB were aliphatic and monoaromatic hydrocarbons, respectively. Syngas products from air gasification of hydrochars were 39.9–56.5 %, 11.4–21.4 %, and 9.0–14.4 % for CO, H 2 and CH 4 , respectively while CO 2 /O 2 gasification products yielded 45.1–56.6 %, 11.6–24.3 %, and 9.4–14.0 % for CO, H 2 and CH 4 , respectively. The lower heating value of syngas was in the range of 4.7–6.6 MJ/Nm3 and cold gas efficiency was approximately 39.1–55.1 %. The cumulative methane from the liquid products amounted to 213.8 and 154.5 L/kg COD for food/microorganism ratios of 1:2 and 1:3, respectively. The mass and energy balance showed that the whole process is promising for future commercialization. [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]