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Now showing items 1 - 10 of 10

  • Pore Characteristics and Slurryability of Coal Blends

    Zhu, Jie-Feng   Wang, Jie   Liu, Jian-Zhong   Cheng, Jun   Wang, Zhi-Hua   Zhou, Jun-Hu   Cen, Ke-Fa  

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  • Pore Characteristics and Slurryability of Coal Blends

    Zhu, Jie-Feng   Wang, Jie   Liu, Jian-Zhong   Cheng, Jun   Wang, Zhi-Hua   Zhou, Jun-Hu   Cen, Ke-Fa  

    The pore characteristics and slurryability of two coal blends between Shigang anthracite coal and Huangling bituminous coal (SG/HL), and Guizhou anthracite coal and Xiaotun lean coal (GZ/XT), respectively, were investigated. The fractal dimensions of coal were calculated in the two regions of P/P-0 < 0.45 and P/P-0 > 0.45 and defined as D, and D-2, respectively. Upon an increase in the blending ratio of parent coal with smaller BET surface area (SBET) and total pore volume (TPV), the S-BET and TPV of coal blends monotonously decreased. D-1 was mainly related to the Smeso/macro(10-220 nm)/S-total and mineral phase within coal while D-2 was closely affected by the Vmeso(2-10 nm)/V-total. D-1 of SG/HL coal blends had no apparent linear correlation with the pore structure parameters whereas I), of GZ/XT coal blends changed linearly with the pore structure parameters. Both D-2 of SG/HL coal blends and that of GZ/XT coal blends changed linearly with the pore structure parameters. The slurry quality of coal water slurry (CWS) prepared from coal blends is comprehensively affected by the physicochemical properties and blending ratio of parent coals. Therefore, the maximum solid loading (MSL) and water separation ratio (WSR) of CWS prepared from coal blends do not always change linearly with the blending ratio of parent coal.
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  • Effect of microwave irradiation on the grinding characteristics of Ximeng lignite

    Zhu, Jie-Feng   Liu, Jian-Zhong   Yuan, Shao   Cheng, Jun   Liu, Yan   Wang, Zhi-Hua   Zhou, Jun-Hu   Cen, Ke-Fa  

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  • Effects of different drying methods on the grinding characteristics of Ximeng lignite

    Zhu, Jie-Feng   Liu, Jian-Zhong   Wu, Jun-Hong   Cheng, Jun   Wang, Zhi-Hua   Zhou, Jun-Hu   Cen, Ke-Fa  

    Ximeng lignite (XL) was treated by using different drying methods, namely, conventional, microwave, and combination, to investigate their effects on the grinding characteristics of XL. The controlled mechanisms that improved the grindability of XL treated by different drying methods were analyzed with proximate analysis and scanning electron microscope. Results showed that the removal moisture and the physical structure damage induced by thermal stress or steam jet flow improved the grindability of treated XL. Microwave drying had the most remarkable effect on the grindability of XL. The increments in grindability of XL irradiated for 0.5 and 3 min were 44.03% and 200.45%, respectively. Compared with conventional dying, combined drying simultaneously improved grindability of XL, and reduced energy consumption. However, combined drying reduced the effects of microwave drying on the increment in the grindability of XL. Drying treatment for a short period could not effectively increase the mass fraction of finely ground product unless drying time was properly prolonged. According to the economy evaluation at lab scale, treatment of XL by microwave drying for a short period improved the grindability of treated XL and achieved a maximum energy saving of around 10% after a long period of the grinding process. (C) 2015 Elsevier Ltd. All rights reserved.
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  • Effects of different drying methods on the grinding characteristics of Ximeng lignite

    Zhu, Jie-Feng   Liu, Jian-Zhong   Wu, Jun-Hong   Cheng, Jun   Wang, Zhi-Hua   Zhou, Jun-Hu   Cen, Ke-Fa  

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  • Thin-layer drying characteristics and modeling of Ximeng lignite under microwave irradiation

    Zhu, Jie-Feng   Liu, Jian-Zhong   Wu, Jun-Hong   Cheng, Jun   Zhou, Jun-Hu   Cen, Ke-Fa  

    The thin-layer drying characteristics of Ximeng lignite (XL) were investigated under microwave irradiation, and mathematical modeling using thin-layer drying models from literature was performed. The effects of coal particle size and microwave power level on drying characteristics were studied. The drying rate increased and drying time decreased with increasing particle size or microwave power level. The drying rate and drying rate to moisture ratio curves, which contained a constant rate period at lower microwave output powers, exhibited fast heating and falling rate periods at different coal-particle sizes and microwave output power levels. Among the 14 thin-layer drying models proposed, the Midilli-Kucuk model provided a better fit for all applied drying conditions and could be used to estimate moisture in XL at any time during the microwave-drying process after running a multiple regression analysis. The drying rate constants and apparent diffusion coefficients (determined from the Midilli-Kucuk model and Fick's second law, respectively) increased with increasing particle size or microwave power level. The activation energy estimated from a modified Arrhenius equation was E-a = 77.0485 W/g. The equilibrium moisture of XL decreased with increasing microwave output power or decreasing particle size. (C) 2014 Elsevier B.V. All rights reserved.
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  • Synthesis of Spirofluorenyl-beta-Lactams through Cycloaddition and Ring Contraction from N-Aryl Fluorenone Nitrones and Methylenecyclopropanes

    Wei, Cui   Zhu, Jie-Feng   Zhang, Jin-Qi   Deng, Qi   Mo, Dong-Liang  

    A variety of spirofluorenyl-beta-lactams have been prepared in moderate yields over three steps from N-aryl fluorenone nitrones and methylenecyclopropanes through a [3+2] cycloaddition, reduction and subsequent acid-catalyzed ring contraction cascade strategy under mild reaction conditions. Experimental studies showed that the stereochemistry remained intact after the ring contraction step. Furthermore, the obtained spirofluorenyl-beta-lactam was easily converted to two novel spiroazetidine and spiroquinolinone scaffolds in good yields.
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  • Fractal characteristics of pore structures in 13 coal specimens:Relationship among fractal dimension,pore structure parameter,and slurry ability of coal

    Zhu, Jie-Feng   Liu, Jian-Zhong   Yang, Yu-Meng   Cheng, Jun   Zhou, Jun-Hu   Cen, Ke-Fa  

    The fractal characteristics of pore structures in 13 different coal specimens were investigated. Insights into the relationship among fractal dimension, pore structure parameter, and slurry ability of coal were provided. N-2 adsorption/desorption at 77 K was applied to analyze the pore structure of coal. Two fractal dimensions, D-1 and D-2, at relative pressures of 0 to 0.45 and 0.45 to 1, respectively, were calculated with the fractal Frenkel-Halsey-Hill model. Results reveal that the value of D-1 is mainly affected by the influence of meso- and macro-pores with an average pore size range of 10 nm to 220 nm on the specific surface area; therefore, Di can be utilized to quantitatively describe the surface roughness of these meso- and macro-pores in coal. Meanwhile, the value of D-2 is mainly related to the effects of fine mesopores with an average pore size range of 2 nm to 10 nm on the total pore volume; therefore, D-2 can be utilized to quantitatively describe the volumetric roughness of these mesopores in coal. Di has no apparent linear correlation with the pore structure parameters and maximum solid loading of coal, and D-2 has a positive linear correlation with the specific surface area and total pore volume of coal. The increase in specific surface area, total pore volume, and D-1 has negative effects on the slurry ability of coal. High-rank coals with high ash content and low volatile matter relatively have higher Di and lower D-2. Meanwhile, with increasing coal rank, D-2 has a decreased trend. The fine mesopores with an average pore size range of 2 nm to 10 nm in coal have direct effects on the pore structure parameters and D-2 of coal; thus, the slurry ability of coal may be improved if the number of these mesopores in coal is reduced by modification processes, such as microwave irradiation, hydrothermal treatment and so on. (C) 2016 Elsevier B.V. All rights reserved.
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  • Fractal characteristics of pore structures in 13 coal specimens: Relationship among fractal dimension, pore structure parameter, and slurry ability of coal

    Zhu, Jie-Feng   Liu, Jian-Zhong   Yang, Yu-Meng   Cheng, Jun   Zhou, Jun-Hu   Cen, Ke-Fa  

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  • Cycloaddition of Fluorenone N-Aryl Nitrones with Methylenecyclopropanes and Sequential 1,3-Rearrangement:An Entry to Synthesis of Spirofluorenylpiperidin-4-ones

    Ma, Xiao-Pan   Zhu, Jie-Feng   Wu, Si-Yi   Chen, Chun-Hua   Zou, Ning   Liang, Cui   Su, Gui-Fa   Mo, Dong-Liang  

    A facile synthesis of various spirofluorenylpiperidin-4-ones has been achieved in good yields from fluorenone N-aryl nitrones and methylenecyclopropanes. This method involved an initial cycloaddition to form a 5-spirocyclopropane-isoxazoline, which underwent a highly selective 1,3-rearrangement to give the desired product. The stereochemistry of the spirofluorenylpiperidin-4-one could be controlled by the cycloaddition and sequential rearrangement strategy. Furthermore, the spirofluorenylpiperidin-4-ones could be not only prepared in one-pot procedure but also converted to useful scaffolds by reduction or oxidation conditions.
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