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    Co-combustion dynamics and products of textile dyeing sludge with waste rubber versus polyurethane tires of shared bikes
    (Elsevier Sci LTD, 2023) He, Yao; Chen, Xi; Tang, Xiaojie; Chen, Siqi; Evrendilek, Fatih; Chen, Tao
    The co-combustions of major waste streams such as textile dyeing sludge (TDS) and waste tires of shared bikes may reduce the dependence on fossil fuels, as well as enhance their circular management and the recovery of their value-added products. In this study, the ash-to-gas products, interaction effects, and reaction mechanisms of the co-combustions of TDS and waste tires were characterized. The mono-combustions included the three stages of water evaporation, volatiles release, and mineral decomposition for TDS and the five stages for both rubber (RT) and polyurethane (PUT) tires. The three substages of the main stage of volatiles release for TDS had the activation energy of 124.5, 144.9, and 167.5 kJ/mol and were best explained by the reaction mechanism models of D3, D5, and F2, respectively. The (co-)combustion performance indices rose with the increased heating rate. The blend of 25% TDS with 75% RT (TR) and 75% PUT (TP) led to the best co-combustion performance according to comprehensive combustion index, with TP outperforming TR. The co-combustions of TP and TR reduced the activation energy required for the main devolatilization stage reaction. There was no significant difference in the main reaction mechanisms between the co-combustions. The interaction between TDS and waste tires reduced the applied energy required for the main devolatilization stage. The co-combustions at the low temperature produced O-H, CH4, CO2, CO, SO2, NO, carbonyl products, olefin products, and ketones. The cocombustions increased the production of C-H, reduced SO2 release and the viscosity of their ashes, promoted the complete combustion of substances, and alleviated the scale and sintering issues regardless of TP versus TR and caused the early release of NO from TP. According to the thermodynamic equilibrium simulations, the TR cocombustion promoted the retentions of Ca, S, Si, and Fe, in particular, the fixation of S. The addition of PUT enhanced the combination of Ca and Si into CaSiO3. The optimization based on the artificial neural networks pointed to the temperature range of 400-800 oC and the TR co-combustion as the optimal operational conditions.
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    Co-pyrolytic performances, mechanisms, gases, oils, and chars of textile dyeing sludge and waste shared bike tires under varying conditions
    (Elsevier Science Sa, 2022) Tang, Xiaojie; Chen, Xi; He, Yao; Evrendilek, Fatih; Chen, Zhiyun; Liu, Jingyong
    The massive industrial wastes of textile dyeing sludge (TDS) and waste shared bike tires are becoming increasingly problematic environmentally and economically. Their co-pyrolysis maybe an affordable and ecofriendlier alternative so as to reduce their waste volumes and emissions, as well as recover value-added oils and chars. This study was the first to characterize the TDS co-pyrolysis with rubber (RT) versus polyurethane (PUT) tires and their performances, mechanisms, emissions, oils, and chars as a function of temperature and blend type and ratio. The co-pyrolysis increased the total weight loss from 51.76% with TDS to 55.30% with 50% TDS and 50% RT (TR55) and to 68.92% with TP55. TR55 and TP55 yielded the best performances, with the stronger synergistic effect with the TP than TR co-pyrolysis. The optimal reaction models were second-order (F2) and five-dimension diffusion (D5) for the two devolatilization sub-stages for TDS, two thirds-order (F1.5) for the TR55 and the second and fourth sub-stages of the TP55, and F2 for the first and third sub-stages of the TP55. The co-pyrolysis reduced emissions of CO, SO2, and nitrous compounds, did not change their temperature dependency, and produced more hydrocarbon products. The TR co-pyrolysis produced more D-limonene and isoprene and inhibited the isomerization of D-limonene. The TP co-pyrolysis further decomposed diaminodiphenylmethane into low-molecular weight benzene series such as toluene and styrene. The co-pyrolytic chars had higher branching degree of aliphatic side chain and bridge bond, with the TP ones having the enhanced char aromaticity.
  • Küçük Resim Yok
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    Co-thermal conversion, atmosphere, and blend type controls over heavy metals in biochars and bottom slags of textile dyeing sludge and durian shell
    (Elsevier Sci Ltd, 2023) Liu, Hui; Chen, Xi; Wei, Xipeng; Chen, Zhibin; Yuan, Haoran; Evrendilek, Fatih; Huang, Shengzheng
    The co-thermal conversions of textile dyeing sludge ((TDS) with biomass may be turned into a feasible and green technology to valorize energy and products, but the transformation behavior of heavy metals remains unclear. This study aimed to quantify the migrations and distributions of HMs in biochars and bottom slags and their environmental risks in response to the co-pyrolysis and co-combustion of durian shell (DS) and TDS, atmosphere type, blend ratio, and temperature. The co-combustion interaction of DS and TDS raised the residual HM contents of the bottom slag. Co-pyrolysis reduces the environmental risks of HMs of the TDS, and the effect of CO2 atmosphere is better. In 80N(2)20O(2), Cr, Zn, and Cu in the TDS bottom slag had the highest leaching toxicity concentrations at 900 degrees C. At 800 degrees C, the leaching toxicity concentrations of HMs were Cr > Cu > Zn > Mn in TDS. The O-2 concentration and atmosphere type did not significantly affect the HM morphology and transformation. K increased the temperature of converting solid-phase Ni to slag-phase NiO in DS sample and affected the transformation temperature and strength of Ni, Zn, and Pb in other sample at the high temperature. The combined results of all the three optimizations of HM contents, forms, and risks pointed to add 50 % DS in the N-2 atmosphere and add 50 % DS in 50N(2)50O(2) and 80CO(2)20O(2) atmospheres as the optimal co-pyrolysis/combustion settings, respectively.