The Experts below are selected from a list of 462 Experts worldwide ranked by ideXlab platform
Jianliang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Catalytic graphitization of Coke Carbon by iron: Understanding the evolution of Carbon Structure, morphology and lattice fringes
Fuel, 2020Co-Authors: Hang Zhang, Jianliang Zhang, Minmin SunAbstract:Abstract The catalytic graphitization process of Coke Carbon with iron was investigated in the temperature range of 1100 °C–1500 °C using X-ray diffraction, scanning electron microcopy, high-resolution transmission electron microscopy (HRTEM). The evolution of micro-crystal graphite lattice fringes was carefully analyzed by image processing of the HRTEM micrographs. A strong catalytic effect of iron on graphitization was observed at temperature above 1200 °C with an obvious increase of Carbon structural orders. Iron was found to promote the decrease of d0 0 2 value and increase of Lc values of the turbostratic Carbon, while the d0 0 2 value of the newly formed graphitic Carbon is quite below that of the commercial graphite when it just forms at 1200 °C. The melting point of iron particles were decreased due to the significant Carbon dissolution into iron, leading to the melting and aggregation of iron. The lattice fringe length and the stacking number of micro-crystal graphite were found to increase obviously, while no clear change of crystal orientation was observed. This indicates that the growth of micro-crystal graphite was along its original orientation. The Carbon dissolution – graphite precipitation mechanism can be used to explain the catalytic graphitization process very well.
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insights into phase and mineral matter of metallurgical Coke in cohesive zone
Fuel, 2019Co-Authors: Zhiyu Chang, Xiaojun Ning, Jianliang ZhangAbstract:Abstract A series of Coke samples collected from cohesive zone were examined by SEM/EDS. The forsterite, octahedral spinel crystal and silicon reduced from quartz particles were found in Coke. Besides the Coke, the alkalis aluminosilicate minerals were also distributed in the slag, iron and iron oxide layer. Many spinel crystalline phases presented in the slag will increase the slag viscosity and affect slag flow through the Coke bed. The coexistence of sodium enrichment and graphite precipitated from iron phase implies key clues for the formation of intercalation compounds with micro graphite crystals of Coke, probably providing an additional degradation mechanism for the Coke in cohesive zone. Iron sulfides, iron phosphides, reduced silicon and the crystalline phases rich in Ca-Al were expected to affect the Coke Carbon-dissolution reaction.
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Atomic-Scale Understanding about Coke Carbon Structural Evolution by Experimental Characterization and ReaxFF Molecular Dynamics
Energy & Fuels, 2019Co-Authors: Minmin Sun, Jianliang Zhang, Hang Zhang, Shan Ren, Mansoor BaratiAbstract:Atomic-scale structural transformation of Coke Carbon in the thermal annealing process was investigated with four Coke Carbon samples using X-ray diffraction, Raman spectroscopy, X-ray photoemissio...
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Influence of alkaline (Na, K) vapors on Carbon and mineral behavior in blast furnace Cokes
Fuel, 2015Co-Authors: Jianliang Zhang, Xiaojun Ning, Shan Ren, Mansoor Barati, Rita Khanna, Zhengjian Liu, Jianbo Zhong, Tianjun Yang, Veena SahajwallaAbstract:Abstract A series of adsorption–alkalization experiments were conducted in a muffle furnace on two types of blast furnace Cokes at 1300 °C in the presence of alkali vapors. Coke textures were found to peel off layer by layer after the alkalization process by potassium vapor, and macro fissures were observed for K/Coke ratios higher than 3/100. This phenomenon was not observed in the Coke samples alkalized by sodium vapor. A number of additional potassium-bearing and sodium-bearing phases were detected with scanning electron microscope and energy dispersive spectrometer after the alkalization process. The formation of kalsilite or potassium aluminum silicate (KAlSiO 4 ) and sodium alumina silicates (Na 6 Al 4 Si 4 O 17 ) was confirmed through X-ray diffraction, however the formation of intercalation compounds that were expected to form in the alkalized Coke samples could not be confirmed. The catalytic effect of sodium and potassium-bearing minerals appeared to be quite similar; the degradation of Coke strength by sodium was however found to be stronger than that caused by potassium. The severe degradation of Coke quality caused by alkali vapors was attributed to their strong influence on the Coke Carbon matrix, Coke minerals, as well as their catalytic effect on the Carbon gasification reaction.
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gasification of graphite and Coke in Carbon Carbon dioxide sodium or potassium Carbonate systems
Industrial & Engineering Chemistry Research, 2014Co-Authors: Kejiang Li, Xiaojun Ning, Jianliang Zhang, Tianqiu WangAbstract:The thermodynamics of possible reactions, including gasification and reduction reactions, in Carbon–Carbon dioxide–sodium or potassium Carbonate systems was analyzed first. And then, the gasification reactions of graphite and Coke with CO2 in this system were studied kinetically by temperature programmed thermogravimetry. The results showed that the Carbon conversion curve shifted to a lower temperature zone after Na2CO3 or K2CO3 was added, and graphite was more susceptible than Coke to be catalyzed by Na2CO3 or K2CO3. Ten kinetic equations were adopted to simulate the reaction process using the method of Coats–Redfern. The Avrami–Erofeev equation was found to be the most probable kinetic equation, with which the values of activation energy and frequency factor were calculated. The kinetic simulation indicated that the activation energy of Coke Carbon had been activated to the lowest level by its inner factors, thus it was difficult to be reduced by adding Na2CO3 or K2CO3. The kinetic compensation effect ...
V. V. Salomatov - One of the best experts on this subject based on the ideXlab platform.
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Heat and mass transfer in a coal-water fuel particle at the stage of “thermal” treatment
Thermophysics and Aeromechanics, 2016Co-Authors: V. V. Salomatov, S. V. Syrodoy, G. V. KuznetsovAbstract:The problem of heat and mass transfer has been solved numerically under the conditions of coal-water fuel particle ignition. The concurrent processes of evaporation, filtration of steam, thermal decomposition of the organic part of coal, thermal and chemical interaction of steam and Coke Carbon, and oxidation of products of their reaction and volatiles by the external oxidizer have been taken into account. The scales of influence of individual thermophysical and thermochemical properties of coals on the characteristics and conditions of ignition of coal-water slurry have been determined.
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The influence of heat transfer conditions on the parameters characterizing the ignition of coal-water fuel particles
Thermal Engineering, 2015Co-Authors: S. V. Syrodoy, G. V. Kuznetsov, V. V. SalomatovAbstract:The future of thermal power engineering both in Russia and abroad will depend in many respects on the use of coal as main fuel for generating heat and electricity. In this connection, matters concerned with development and introduction of new environmentally friendly and energy efficient coal firing technologies are becoming of much importance. Firing coal in the form of coal-water fuel is one of the most promising solutions. However, despite a rather long history of its development (more than 40 years), this technology has not found wide use as yet, which in all likelihood is due to lack of full mathematical and physicochemical models describing the processes that take place when a coal-water fuel particle undergoes thermal treatment and ignition. The article presents the results obtained from numerical solution of the coal-water fuel particle ignition problem taking into account simultaneously occurring main thermal treatment processes (thermal conductivity, water evaporation, filtration heat and mass transfer, thermal decomposition of the fuel organic part, and thermochemical interaction between water vapor and Coke Carbon). The ignition problem is solved using the finite difference method. For calculating the evaporation process taking into account nonequilibrium nature of the parameters at the interface boundary of the initial “coal-water fuel—dry coal” system, the method of capturing the phase transition front at the difference mesh node was used. The results obtained from numerical modeling were used for determining the conditions and parameters characterizing the ignition of coal-water fuel particles under the conditions typically existing in the furnace space of boiler units. The extent to which radiant heat transfer influences the ignition delay time is determined. It is shown that radiant heat transfer plays a determining role in the thermal preparation of fuel for ignition.
Veena Sahajwalla - One of the best experts on this subject based on the ideXlab platform.
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Influence of alkaline (Na, K) vapors on Carbon and mineral behavior in blast furnace Cokes
Fuel, 2015Co-Authors: Jianliang Zhang, Xiaojun Ning, Shan Ren, Mansoor Barati, Rita Khanna, Zhengjian Liu, Jianbo Zhong, Tianjun Yang, Veena SahajwallaAbstract:Abstract A series of adsorption–alkalization experiments were conducted in a muffle furnace on two types of blast furnace Cokes at 1300 °C in the presence of alkali vapors. Coke textures were found to peel off layer by layer after the alkalization process by potassium vapor, and macro fissures were observed for K/Coke ratios higher than 3/100. This phenomenon was not observed in the Coke samples alkalized by sodium vapor. A number of additional potassium-bearing and sodium-bearing phases were detected with scanning electron microscope and energy dispersive spectrometer after the alkalization process. The formation of kalsilite or potassium aluminum silicate (KAlSiO 4 ) and sodium alumina silicates (Na 6 Al 4 Si 4 O 17 ) was confirmed through X-ray diffraction, however the formation of intercalation compounds that were expected to form in the alkalized Coke samples could not be confirmed. The catalytic effect of sodium and potassium-bearing minerals appeared to be quite similar; the degradation of Coke strength by sodium was however found to be stronger than that caused by potassium. The severe degradation of Coke quality caused by alkali vapors was attributed to their strong influence on the Coke Carbon matrix, Coke minerals, as well as their catalytic effect on the Carbon gasification reaction.
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recycling end of life polymers in an electric arc furnace steelmaking process fundamentals of polymer reactions with slag and metal
Energy & Fuels, 2012Co-Authors: Veena Sahajwalla, Magdalena Zaharia, Somoyote Kongkarat, Rita Khanna, Muhammad Faz Rahman, N Sahachaudhury, Paul Okane, Jonathan Dicker, Catherine Skidmore, David KnightsAbstract:Research on the use of waste polymeric materials is one of the solutions for developing environmentally friendly recycling processes for steelmaking. Different polymeric materials [i.e., rubber, high-density polyethylene (HDPE), polyethylene therephtalate (PET), and Bakelite], which have different chemical structures and compositions, were selected for this study as Carbon resources. The rapid heating to high temperatures provided during steelmaking will break down the polymeric chains and reactions with liquid slag, enabling gas formation. The dynamic changes in the volume of the slag droplet while in contact with the Coke/polymer substrates are measured. Significant levels of gas generation and entrapment are present, leading to an improved performance over Coke. Carbon/metal reactions were studied by measuring Carbon and sulfur pick-up by liquid metal as well as the formation of reaction products at the metal/Carbon interface. The measured Carbon pick-up value after 2 min of reaction for metallurgical ...
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Characterization of Thermal Annealing Effects on the Evolution of Coke Carbon Structure Using Raman Spectroscopy and X-ray Diffraction
ISIJ International, 2006Co-Authors: Masahiro Kawakami, Haruki Kanba, Kazunori Sato, Toshihide Takenaka, Sushil Gupta, R. Chandratilleke, Veena SahajwallaAbstract:An experimental study was conducted to monitor the evolution of Coke Carbon structure during thermal annealing in a temperature range from 1273 to 2473 K in a bench-scale reactor. Coke Carbon structure was characterized by using Raman Spectroscopy and the X-ray Diffraction. The Raman spectra of most of the Cokes displayed two broad peaks G* (1620 cm−1) and D* (1360 cm−1). Both Raman peaks were deconvoluted into five peaks namely G, D, D′, R1 and R2. On the basis of area under the respective band peaks, new structural parameters were obtained to quantify graphitic (G), graphitic defect (D) and random (R) Carbon fractions of Cokes.XRD analysis was used to show that stack height Carbon crystallite, Lc, of Coke increases with increasing annealing temperature while the impact of annealing duration was not significant particularly up to 1873 K. On the other hand, average Carbon crystallite width, La, did not improve significantly up to 1873 K, and increased rapidly after subsequent rise in the annealing temperature. It appears that during annealing up to 1873 K, modification of Coke Carbon structure could occur due to loss of basal Carbon as a consequence of in-situ gasification.The lateral expansion of Carbon crystallite, La, was related to relative intensity or shape of Raman band peaks such that both parameters did not change significantly up to an annealing temperature of 1873 K. At higher annealing temperatures, La values of Coke increased with decreasing D/G ratio. Lateral expansion of Carbon crystallite was attributed to progressive reduction of defects of graphitic Carbon of Coke, which can be monitored by D fraction of Raman Analysis. Combined Raman and XRD analysis suggested that rapid graphitization of Coke may not occur along all dimensions until the annealing temperature exceeds 1873 K.Combining XRD and Raman analysis would provide a comprehensive evaluation of the evolution of Coke Carbon structure at different temperatures and their subsequent implications on the efficiency of various ironmaking operations.
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degradation behaviour of a high csr Coke in an experimental blast furnace effect of Carbon structure and alkali reactions
Isij International, 2005Co-Authors: Tobias Hilding, Sushil Gupta, Veena Sahajwalla, Bo Bjorkman, Janolov WikstromAbstract:A high CSR Coke was tested in the LKAB’s Experimental Blast Furnace (EBF) at Lulea. The evolution of physical and chemical properties of the centre-line Coke samples were analysed by Light Optical Microscopy (LOM), BET N2 absorption and SEM/XRF/XRD. Alkali distribution in the EBF Cokes was examined by XRF/SEM and EDS. Thermo Gravimetric Analysis (TGA) was used to measure isothermal and nonisothermal CO2 reactivity of the Cokes. The crystalline order of Carbon and the concentration of alkalis were found to increase as the Coke descended through thermal reserve zone to the cohesive zone of the EBF. The crystallite height (Lc) of EBF Coke Carbon displayed a linear correlation with the measured EBF temperatures demonstrating the strong effect of temperature on Carbon structure of Coke in the EBF. Alkali concentration of the Coke was increased as it descended into the EBF, and was uniformly distributed throughout the Coke matrix. The CO2 reactivity of lower zone Cokes was found to increase when compared to the reactivity of the upper zones Cokes, and was related to the catalytic effect of increased alkalis concentration. The deterioration of Coke quality particularly Coke strength and abrasion propensity were related to Coke graphitisation, alkalization and reactivity. Coke graphitisation is shown to have a strong influence on the Coke degradation behaviour in the EBF.
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Carbon structure of Coke at high temperatures and its influence on Coke fines in blast furnace dust
Metallurgical and Materials Transactions B, 2005Co-Authors: Sushil Gupta, Veena Sahajwalla, Pinakin Chaubal, Ted YoumansAbstract:A thermal annealing study of three industrial Cokes was carried out in a horizontal tube furnace at a range of temperatures up to 1600 °C under N_2. Evolution of the Carbon structure of Cokes was established by determining the stack height (L_002) of aromatic Carbon layers on the basis of the 002 Carbon peak in their X-ray diffraction (XRD) spectra by using the classical Scherrer’s approach. The heat-treatment temperature is shown to have a strong impact on the growth of crystalline order of Coke Carbon by demonstrating a linear correlation between the Carbon crystallite height (L_002) and the annealing temperature. The intensity of the thermal effects on the growth of the crystalline order of Coke Carbon is influenced by the Coke ash chemistry, particularly with the iron content of the Coke. The Carbon structure of blast furnace (BF) dust samples was also analyzed by using XRD and scanning electron microscopy (SEM). Under a similar range of heat-treatment temperatures, growth of the Carbon crystallite (L_002) of Coke, in both the laboratory and the industrial BF, was found to be of the same order of magnitude. The correlation between the Carbon structure (L_002) of Coke and the annealing temperature is used to ascertain the temperature of the origin of Coke fines in a BF. The Carbon structure of Coke is shown to have a significant influence on the Coke behavior in a BF such that highly ordered Coke displayed lower reactivity as well as higher proportion of Coke fines in the dust. The Carbon structure of Coke fines in BF dust has been shown as an indicator of the crystallite dimension (L_002) of the Coke in a BF, and has a potential to assess Coke performance, particularly of the Coke fine generations from different thermal regimes of a BF and also their subsequent consumption.
Xiaojun Ning - One of the best experts on this subject based on the ideXlab platform.
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insights into phase and mineral matter of metallurgical Coke in cohesive zone
Fuel, 2019Co-Authors: Zhiyu Chang, Xiaojun Ning, Jianliang ZhangAbstract:Abstract A series of Coke samples collected from cohesive zone were examined by SEM/EDS. The forsterite, octahedral spinel crystal and silicon reduced from quartz particles were found in Coke. Besides the Coke, the alkalis aluminosilicate minerals were also distributed in the slag, iron and iron oxide layer. Many spinel crystalline phases presented in the slag will increase the slag viscosity and affect slag flow through the Coke bed. The coexistence of sodium enrichment and graphite precipitated from iron phase implies key clues for the formation of intercalation compounds with micro graphite crystals of Coke, probably providing an additional degradation mechanism for the Coke in cohesive zone. Iron sulfides, iron phosphides, reduced silicon and the crystalline phases rich in Ca-Al were expected to affect the Coke Carbon-dissolution reaction.
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Influence of alkaline (Na, K) vapors on Carbon and mineral behavior in blast furnace Cokes
Fuel, 2015Co-Authors: Jianliang Zhang, Xiaojun Ning, Shan Ren, Mansoor Barati, Rita Khanna, Zhengjian Liu, Jianbo Zhong, Tianjun Yang, Veena SahajwallaAbstract:Abstract A series of adsorption–alkalization experiments were conducted in a muffle furnace on two types of blast furnace Cokes at 1300 °C in the presence of alkali vapors. Coke textures were found to peel off layer by layer after the alkalization process by potassium vapor, and macro fissures were observed for K/Coke ratios higher than 3/100. This phenomenon was not observed in the Coke samples alkalized by sodium vapor. A number of additional potassium-bearing and sodium-bearing phases were detected with scanning electron microscope and energy dispersive spectrometer after the alkalization process. The formation of kalsilite or potassium aluminum silicate (KAlSiO 4 ) and sodium alumina silicates (Na 6 Al 4 Si 4 O 17 ) was confirmed through X-ray diffraction, however the formation of intercalation compounds that were expected to form in the alkalized Coke samples could not be confirmed. The catalytic effect of sodium and potassium-bearing minerals appeared to be quite similar; the degradation of Coke strength by sodium was however found to be stronger than that caused by potassium. The severe degradation of Coke quality caused by alkali vapors was attributed to their strong influence on the Coke Carbon matrix, Coke minerals, as well as their catalytic effect on the Carbon gasification reaction.
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gasification of graphite and Coke in Carbon Carbon dioxide sodium or potassium Carbonate systems
Industrial & Engineering Chemistry Research, 2014Co-Authors: Kejiang Li, Xiaojun Ning, Jianliang Zhang, Tianqiu WangAbstract:The thermodynamics of possible reactions, including gasification and reduction reactions, in Carbon–Carbon dioxide–sodium or potassium Carbonate systems was analyzed first. And then, the gasification reactions of graphite and Coke with CO2 in this system were studied kinetically by temperature programmed thermogravimetry. The results showed that the Carbon conversion curve shifted to a lower temperature zone after Na2CO3 or K2CO3 was added, and graphite was more susceptible than Coke to be catalyzed by Na2CO3 or K2CO3. Ten kinetic equations were adopted to simulate the reaction process using the method of Coats–Redfern. The Avrami–Erofeev equation was found to be the most probable kinetic equation, with which the values of activation energy and frequency factor were calculated. The kinetic simulation indicated that the activation energy of Coke Carbon had been activated to the lowest level by its inner factors, thus it was difficult to be reduced by adding Na2CO3 or K2CO3. The kinetic compensation effect ...
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Gasification of Graphite and Coke in Carbon–Carbon Dioxide–Sodium or Potassium Carbonate Systems
Industrial & Engineering Chemistry Research, 2014Co-Authors: Jianliang Zhang, Xiaojun Ning, Zhengjian Liu, Tianqiu WangAbstract:The thermodynamics of possible reactions, including gasification and reduction reactions, in Carbon–Carbon dioxide–sodium or potassium Carbonate systems was analyzed first. And then, the gasification reactions of graphite and Coke with CO2 in this system were studied kinetically by temperature programmed thermogravimetry. The results showed that the Carbon conversion curve shifted to a lower temperature zone after Na2CO3 or K2CO3 was added, and graphite was more susceptible than Coke to be catalyzed by Na2CO3 or K2CO3. Ten kinetic equations were adopted to simulate the reaction process using the method of Coats–Redfern. The Avrami–Erofeev equation was found to be the most probable kinetic equation, with which the values of activation energy and frequency factor were calculated. The kinetic simulation indicated that the activation energy of Coke Carbon had been activated to the lowest level by its inner factors, thus it was difficult to be reduced by adding Na2CO3 or K2CO3. The kinetic compensation effect ...
Jinlong Zhang - One of the best experts on this subject based on the ideXlab platform.
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Vacuum activation-induced Ti 3+ and Carbon co-doped TiO 2 with enhanced solar light photo-catalytic activity
Research on Chemical Intermediates, 2015Co-Authors: Yi Zhou, Mingyang Xing, Jinlong ZhangAbstract:Ti3+ and Carbon co-doped TiO2 photocatalysts were prepared hydrothermally to introduce the Carbon, and followed by simple vacuum activation to achieve the Ti3+ self-doping. The prepared co-doped photocatalysts were characterized by XRD, TEM, UV–Vis absorption spectra, EPR, and XPS. It was found that the co-doped TiO2 has dispersed nanoparticles and a narrower band-gap compared with the un-doped TiO2 and single-doped TiO2. The experimental results displayed that the Coke Carbon generated on the surface of co-doped TiO2 acts as a photosensitizer and has the photosensitization effect under solar light irradiation. Except for the Carbon sensitization effect, the Ti3+ self-doping modification has a synergistic effect which is the reason for the effective photo-degradation of methyl orange under simulated solar light irradiation.
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Facile preparation of C-modified TiO2 supported on MCF for high visible-light-driven photocatalysis
RSC Advances, 2015Co-Authors: Bocheng Qiu, Mingyang Xing, Chengchao Zhong, Jinlong ZhangAbstract:A green and facile approach is employed to prepare an efficient visible-light-driven photocatalyst by using mesocellular foams (MCF) as a matrix, glucose as a Carbon-modified source and TiO2 as the catalytic active site, which is denoted as C-modified TiO2/MCF. Characterization results reveal that nano-sized TiO2 nanoparticles are loaded in the pore channels of MCF rather than being aggregated on the surface of the MCF. Furthermore, glucose selectively covers the surface of the TiO2/MCF composites during the stirring process due to the excellent adsorption capacity of MCF, and glucose then can be transformed into Coke Carbon through a hydrothermal process. In addition, a facile thermal treatment is adopted to enhance the visible light photocatalytic activity of the TiO2/MCF composites. It is believed that the post-thermal treatment plays a significant role in controlling the Carbon diffusion from the surface to the bulk of TiO2. Compared to traditional C-TiO2 photocatalysts, the prepared C-doped catalyst exhibits stable Carbon doping of TiO2, superior adsorption capacity and higher visible light photocatalytic activity owing to the special structure of the supported mesoporous catalyst. This study implies that the novel photocatalyst has good application prospects in photocatalytic water splitting, dye-sensitized solar cells and other fields.
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Gel-hydrothermal synthesis of Carbon and boron co-doped TiO2 and evaluating its photocatalytic activity
Journal of hazardous materials, 2011Co-Authors: Mingyang Xing, Jinlong ZhangAbstract:Abstract Carbon and boron co-doped TiO 2 photocatalysts were prepared firstly by the gel-hydrothermal method, that is, synthesized through sol–gel process followed by hydrothermal in the glucose solution. The prepared photocatalysts were characterized by XRD, Raman spectra, TEM, N 2 physical adsorption, XPS, and UV–vis absorption spectra. It was found that the co-doped TiO 2 has a larger BET surface areas and a narrower band gap than undoped TiO 2 . The experimental results show that the Coke Carbon generated on the Carbon doped TiO 2 surface act as a photosensitizer and has the photosensitization effect under the visible light. Except for Carbon sensitization effect, the boron and Carbon co-doped TiO 2 has synergistic effect which is responsible for effective photo-degradation of 2,4-dichlorophenol in the visible light irradiation.