The Experts below are selected from a list of 1563 Experts worldwide ranked by ideXlab platform
Karen M. Steel - One of the best experts on this subject based on the ideXlab platform.
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influence of Coal thermoplastic properties on coking pressure generation part 2 a study of binary Coal blends and specific additives
Fuel, 2010Co-Authors: John J. Duffy, Merrick R Mahoney, Karen M. SteelAbstract:A number of Coal blends and pitch/Coal blends were evaluated using rheometry, thermogravimetric analysis and microscopy to confirm and further elucidate the coking pressure mechanism previously proposed by Duffy et al. (2007) [1]. We confirm that blending a low Rank, high fluidity, low coking pressure Coal, with a high Rank, low fluidity, high coking pressure Coal can significantly reduce the coking pressure associated with the latter. Interestingly, blending does not necessarily result in a fluidity that is midway between that of the two Coals; sometimes the fluidity of the blend is less than that of the low fluidity Coal, especially when the Coals are significantly different in Rank. This occurs because the increase in complex viscosity (η*) through resolidification of the low Rank, high fluidity Coal counteracts the reduction in η* resulting from softening of the high Rank, low fluidity Coal. It has also been confirmed that the η* of the resultant blend can be estimated from the η* of each component Coal using a logarithmic additivity rule commonly employed for polymer blends. Polarised light microscopy has indicated that the degree of mixing between Coals of different Rank is minimal, with fusion restricted to the particle surface. It is therefore inappropriate to think of such a Coal blend in the same way as a single Coal, since each component Coal behaves relatively independently. This limited fusion is important for understanding the coking pressure mechanism for blends. It is proposed here that the Lower Rank Coal, which softens at Lower temperature, is able to expand into the interparticle voids between the high Rank Coal that is yet to soften, and these voids can create channels for volatiles to traverse. Then, and importantly, when the high Rank Coal begins to expand, the pore structure developed in the resolidified structures of the low Rank Coal can facilitate removal of volatiles, while the resolidified material may also act as a suitable sorbent for volatile matter. This is considered to be the primary mechanism by which Coal blending is able to alleviate coking pressure, and applies to addition of inert material also. Addition of a Coal tar pitch was found to increase fluidity but also to extend the thermoplastic range to Lower temperatures. This caused an increase in the swelling range, which was accompanied by a long plateau in η*, a feature which has previously been observed for certain high fluidity, high pressure Coals. Elasticity and η* at the onset of expansion were also higher for both the pitch impregnated Coals and the high pressure blends, which supports previous findings for singly charged high pressure Coals, and confirms the potential use of such criteria for identifying potentially dangerous Coals/blends. © 2009 Elsevier Ltd. All rights reserved.
Lei Zhang - One of the best experts on this subject based on the ideXlab platform.
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Molecular insight into the mechanism of benzene ring in nonionic surfactants on low-Rank Coal floatability
Journal of Molecular Liquids, 2020Co-Authors: Jianying Guo, Lei Zhang, Shengyu Liu, Boris Albijanic, Xiaole SunAbstract:Abstract In this work, a combined molecular dynamics (MD) simulations and experiments were adopted to study the microscopic mechanism of the benzene ring in nonionic surfactants on low-Rank Coal (LRC) flotation. Two nonionic surfactants with identical headgroups, nonylphenol ethoxylate (NPEO) and dodecyl ethoxyl ethers (C12EO), were selected as the research objects. Two LRC surface models with varying metamorphism degrees were constructed. The rationality of the constructed surface models was firstly discussed from the chemical composition and structure. The morphology of the surfactants and the adsorption energy obtained by MD suggested that the arrangement of polar oxygen atoms in the surfactant depended on its interaction with the polar groups of LRC, and the presence of the benzene ring in the nonionic surfactant hardly changed its arrangement on the LRC surface. The benzene ring in the nonionic surfactant can enhance its adsorption on the higher Rank Coal surface via the π-bonds while it cannot promote its adsorption on the Lower Rank Coal surface. The results obtained from the experiments are in accordance with the simulation results.
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Devolatilization and kinetics of maceral concentrates of bituminous Coals
Fuel Processing Technology, 2016Co-Authors: Lei ZhangAbstract:Abstract The potential of achieving effective utilization for a given Coal using maceral separation is dependent on the differences in thermal characteristics of its maceral concentrates. In this paper, vitrinite-rich and inertinite-rich concentrates were obtained from five bituminous Coals with R random ranging from 0.64% to 1.73% using a float-sink procedure. The devolatilization characteristics and kinetics of maceral concentrates were investigated using thermogravimetric analysis at the heating rate of 8 °C/min − 1 from 50 °C to 1200 °C. The devolatilization is comprised of three regions characterized by different weight loss rates. During principal devolatilization, inertinite-rich concentrates are characterized by similar initial temperature, slight greater temperature of maximum rate of weight loss, and greater terminal temperature. The maximum rate of weight loss and the index of volatile matter released decrease with an increase in Rank; the Lower the Rank, the greater the differences between vitrinite-rich and inertinite-rich concentrates. The principal devolatilization displays the greatest apparent activation energy, followed by post-principal devolatilization, and the least for initial devolatilization. During principal devolatilization, the apparent activation energy difference of vitrinite-rich and inertinite-rich concentrates is higher in Lower-Rank Coal and becomes almost zero at the R random of 1.73%. The minimum activation energy and apparent activation energy were in detail discussed.
John J. Duffy - One of the best experts on this subject based on the ideXlab platform.
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influence of Coal thermoplastic properties on coking pressure generation part 2 a study of binary Coal blends and specific additives
Fuel, 2010Co-Authors: John J. Duffy, Merrick R Mahoney, Karen M. SteelAbstract:A number of Coal blends and pitch/Coal blends were evaluated using rheometry, thermogravimetric analysis and microscopy to confirm and further elucidate the coking pressure mechanism previously proposed by Duffy et al. (2007) [1]. We confirm that blending a low Rank, high fluidity, low coking pressure Coal, with a high Rank, low fluidity, high coking pressure Coal can significantly reduce the coking pressure associated with the latter. Interestingly, blending does not necessarily result in a fluidity that is midway between that of the two Coals; sometimes the fluidity of the blend is less than that of the low fluidity Coal, especially when the Coals are significantly different in Rank. This occurs because the increase in complex viscosity (η*) through resolidification of the low Rank, high fluidity Coal counteracts the reduction in η* resulting from softening of the high Rank, low fluidity Coal. It has also been confirmed that the η* of the resultant blend can be estimated from the η* of each component Coal using a logarithmic additivity rule commonly employed for polymer blends. Polarised light microscopy has indicated that the degree of mixing between Coals of different Rank is minimal, with fusion restricted to the particle surface. It is therefore inappropriate to think of such a Coal blend in the same way as a single Coal, since each component Coal behaves relatively independently. This limited fusion is important for understanding the coking pressure mechanism for blends. It is proposed here that the Lower Rank Coal, which softens at Lower temperature, is able to expand into the interparticle voids between the high Rank Coal that is yet to soften, and these voids can create channels for volatiles to traverse. Then, and importantly, when the high Rank Coal begins to expand, the pore structure developed in the resolidified structures of the low Rank Coal can facilitate removal of volatiles, while the resolidified material may also act as a suitable sorbent for volatile matter. This is considered to be the primary mechanism by which Coal blending is able to alleviate coking pressure, and applies to addition of inert material also. Addition of a Coal tar pitch was found to increase fluidity but also to extend the thermoplastic range to Lower temperatures. This caused an increase in the swelling range, which was accompanied by a long plateau in η*, a feature which has previously been observed for certain high fluidity, high pressure Coals. Elasticity and η* at the onset of expansion were also higher for both the pitch impregnated Coals and the high pressure blends, which supports previous findings for singly charged high pressure Coals, and confirms the potential use of such criteria for identifying potentially dangerous Coals/blends. © 2009 Elsevier Ltd. All rights reserved.
Merrick R Mahoney - One of the best experts on this subject based on the ideXlab platform.
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influence of Coal thermoplastic properties on coking pressure generation part 2 a study of binary Coal blends and specific additives
Fuel, 2010Co-Authors: John J. Duffy, Merrick R Mahoney, Karen M. SteelAbstract:A number of Coal blends and pitch/Coal blends were evaluated using rheometry, thermogravimetric analysis and microscopy to confirm and further elucidate the coking pressure mechanism previously proposed by Duffy et al. (2007) [1]. We confirm that blending a low Rank, high fluidity, low coking pressure Coal, with a high Rank, low fluidity, high coking pressure Coal can significantly reduce the coking pressure associated with the latter. Interestingly, blending does not necessarily result in a fluidity that is midway between that of the two Coals; sometimes the fluidity of the blend is less than that of the low fluidity Coal, especially when the Coals are significantly different in Rank. This occurs because the increase in complex viscosity (η*) through resolidification of the low Rank, high fluidity Coal counteracts the reduction in η* resulting from softening of the high Rank, low fluidity Coal. It has also been confirmed that the η* of the resultant blend can be estimated from the η* of each component Coal using a logarithmic additivity rule commonly employed for polymer blends. Polarised light microscopy has indicated that the degree of mixing between Coals of different Rank is minimal, with fusion restricted to the particle surface. It is therefore inappropriate to think of such a Coal blend in the same way as a single Coal, since each component Coal behaves relatively independently. This limited fusion is important for understanding the coking pressure mechanism for blends. It is proposed here that the Lower Rank Coal, which softens at Lower temperature, is able to expand into the interparticle voids between the high Rank Coal that is yet to soften, and these voids can create channels for volatiles to traverse. Then, and importantly, when the high Rank Coal begins to expand, the pore structure developed in the resolidified structures of the low Rank Coal can facilitate removal of volatiles, while the resolidified material may also act as a suitable sorbent for volatile matter. This is considered to be the primary mechanism by which Coal blending is able to alleviate coking pressure, and applies to addition of inert material also. Addition of a Coal tar pitch was found to increase fluidity but also to extend the thermoplastic range to Lower temperatures. This caused an increase in the swelling range, which was accompanied by a long plateau in η*, a feature which has previously been observed for certain high fluidity, high pressure Coals. Elasticity and η* at the onset of expansion were also higher for both the pitch impregnated Coals and the high pressure blends, which supports previous findings for singly charged high pressure Coals, and confirms the potential use of such criteria for identifying potentially dangerous Coals/blends. © 2009 Elsevier Ltd. All rights reserved.
Xiaole Sun - One of the best experts on this subject based on the ideXlab platform.
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Molecular insight into the mechanism of benzene ring in nonionic surfactants on low-Rank Coal floatability
Journal of Molecular Liquids, 2020Co-Authors: Jianying Guo, Lei Zhang, Shengyu Liu, Boris Albijanic, Xiaole SunAbstract:Abstract In this work, a combined molecular dynamics (MD) simulations and experiments were adopted to study the microscopic mechanism of the benzene ring in nonionic surfactants on low-Rank Coal (LRC) flotation. Two nonionic surfactants with identical headgroups, nonylphenol ethoxylate (NPEO) and dodecyl ethoxyl ethers (C12EO), were selected as the research objects. Two LRC surface models with varying metamorphism degrees were constructed. The rationality of the constructed surface models was firstly discussed from the chemical composition and structure. The morphology of the surfactants and the adsorption energy obtained by MD suggested that the arrangement of polar oxygen atoms in the surfactant depended on its interaction with the polar groups of LRC, and the presence of the benzene ring in the nonionic surfactant hardly changed its arrangement on the LRC surface. The benzene ring in the nonionic surfactant can enhance its adsorption on the higher Rank Coal surface via the π-bonds while it cannot promote its adsorption on the Lower Rank Coal surface. The results obtained from the experiments are in accordance with the simulation results.
