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    Co-pyrolytic mechanisms and products of textile dyeing sludge and durian shell in changing operational conditions
    (Elsevier Science Sa, 2021) Liu, Hui; Zhang, Junhui; Liu, Jingyong; Chen, Laiguo; Huang, Hongyi; Evrendilek, Fatih
    Textile dyeing sludge (TDS) is a highly toxic solid waste whose co-pyrolysis can jointly achieve waste reduction and recovery of value-added products. This study aimed to fill the knowledge gaps about the co-pyrolysis mechanisms and products (gases and solids) and their dynamics in response to the atmosphere type, blend ratio, heating rate, temperature, and their interactions. The high temperature pyrolysis (>720 degrees C) in the CO2 atmosphere appeared as the best option for the waste reduction. The (co-)pyrolysis in the CO2 atmosphere enhanced S-containing air pollutants, CO, and CH4 but reduced NOx. The interaction effect between TDS and durian shell (DS) residues promoted the productions of furan and acid compounds and inhibited the productions of aromatic, phenolic, and N-containing compounds. The atmosphere type affected the type and strength of the reactions involved in the production of biochars. Our findings provide practical and new insights into the optimization of energy generation, product recovery, and emission control during the (co-)pyrolysis.
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    Emission-to-ash detoxification mechanisms of co-combustion of spent pot lining and pulverized coal
    (Elsevier, 2021) Chen, Zihong; Liu, Jingyong; Chen, Laiguo; Evrendilek, Fatih; Xie, Wuming; Wu, Xieyuan
    In response to the global initiative for greenhouse gas emission reduction, the co-combustion of coal and spent pot lining (SPL) may cost-effectively minimize waste streams and environmental risks. This study aimed to quantify the emission-to-ash detoxification mechanisms of the co-combustion of SPL and pulverized coal (PC) and their kinetics, gas emission, fluorine-leaching toxicity, mineral phases, and migrations. The main reaction covered the ranges of 335-540 ?C and 540-870 ?C while the interactions occurred at 360-780 ?C. The apparent activation energy minimized (66.99 kJ/mol) with 90% PC addition. The rising PC fraction weakened the peak intensity of NaF and strengthened that of Ca2F, NaAlSiO4, and NaAlSi2O6. The addition of PC enhanced the combustion efficiency of SPL and raised the melting temperature by capturing Na. PC exhibited a positive effect on solidifying water-soluble fluorine and stabilizing alkali and alkaline earth metals. The leaching fluorine concentrations of the co-combustion ashes were lower than did SPL mono-combustion. The main gases emitted were HF, NH3, NOx, CO, and CO2. HF was largely released at above 800 ?C. Multivariate Gaussian process modelbased optimization of the operational conditions also verified the gas emissions results. Our study synchronizes the utilization and detoxification of SPL though co-combustion and provides insights into an eco-friendlier lifecycle control on the waste-to-energy conversion.
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    Multiple drivers, interaction effects, and trade-offs of efficient and cleaner combustion of torrefied water hyacinth
    (Elsevier, 2021) Huang, Hongyi; Liu, Jingyong; Chen, Laiguo; Evrendilek, Fatih; Liu, Hui; Chen, Zhibin
    Developing cleaner and affordable alternatives to the sole reliance on fossil fuels has intensified efforts to improve the thermochemical conversion property of the second-generation lignocellulosic biomass. This study aimed to explore the effects of the two torrefaction temperatures (200 and 300 degrees C), the two reaction atmospheres (N-2/O-2 and CO2/O-2), and the three heating rates (5, 10, and 15 degrees C/min) on the combustion regime of water hyacinth (WH). Decomposition behaviors, reaction kinetics, thermodynamics, and mechanisms, evolved emissions and functional groups, and fuel microstructure properties were quantified. The deoxygenation and dehydration reactions acted as the main drivers of the torrefaction process, with the peak degree of deoxygenation of 8621% for WH torrefied at 300 degrees C (WH300). WH300 significantly reduced the quantity of oxygen-containing functional groups and altered the fuel microstructure properties. The order of the decomposition rates of the pseudo-components were hemicellulose > cellulose > lignin for both WH and WH torrefied at 200 degrees C (WH200) and cellulose > lignin > hemicellulose for WH300. The average activation energy fell from 197.71 to 195.71 kJ/mol for WH, 287.90 to 195.97 Itilmol for WH200, and 226.92 to 184.94 kyrnol for WH300 when the atmosphere changed from N-2/O-2 to CO2/O-2. The heating rate exerted a stronger control on their combustion behaviors than did the reaction atmosphere. CO2 , NO, and NO2 emissions dropped by 46.0, 53.1, and 65.9% for WH200 and 29.6, 42.8, and 62.5% for WH300, respectively, when compared to WH. 473.7 degrees C, 5 degrees C/min, and the CO2/O-2 atmosphere were the optimal settings for the maximized combustion efficiency. 717.1 degrees C was determined as the optimal setting for the minimized combustion emissions. Our study can yield new insights into the large-scale and cleaner combustion of the torrefied water hyacinth. (C) 2021 Elsevier B.V. All rights reserved.