The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Qinggong Wang - One of the best experts on this subject based on the ideXlab platform.
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Numerical study on the effect of fine Coal accumulation in a Coal Beneficiation fluidized bed
Powder Technology, 2015Co-Authors: Qinggong Wang, Junfu Lu, Hairui Yang, Bin ZhaoAbstract:Abstract One important phenomenon in Coal Beneficiation fluidized bed (CBFB) is the accumulation of fine Coal particles in Beneficiation due to poor screening efficiency and attrition of Coal samples. The effect of fine Coal accumulation is numerically studied in this work using a TFM–DEM hybrid model. The gas phase and medium solid phase are modeled by a two-fluid model (TFM), while the fine Coal particles are modeled by the discrete element method (DEM). Particles with a diameter of 0.9 mm are used as the fine Coal sample in the simulation. The gas–solid flow pattern and particle dynamics are investigated with different concentrations of fine Coal particles accumulated in the bed. For model validation purpose, the mean bed density distributions are compared with the experimental reports from He et al. (2013). The results show that a critical particle concentration exists in the fine Coal accumulation process in CBFB. When the fine Coal particles are less than 11 wt% in the bed, the flow pattern of medium phase is little affected and the Coal particles are well mixed in the bed. However, when the particle concentration exceeds this threshold, the uniformity of bed density distribution is destroyed and particle stratification occurs along the bed height according to their density difference. Flow dynamics of the dense bed and main forces acting on the fine Coal particles are analyzed to explain the underlying mechanism. With a large number of particles accumulated in the bed, the mixing effect of medium flow is suppressed. Motion of the fine Coal particles is less dependent on the bed disturbance, instead, the particle gravity plays a decisive role in the particle distribution and results in the particle segregation in the fine Coal accumulation process.
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numerical study of the effect of operation parameters on particle segregation in a Coal Beneficiation fluidized bed by a tfm dem hybrid model
Chemical Engineering Science, 2015Co-Authors: Qinggong Wang, Hairui Yang, Yuqing Feng, Peter J Witt, Weidi Yin, Qing Liu, Lubin WeiAbstract:Abstract A TFM–DEM hybrid model is introduced for modeling of the complex gas–solid flows in a pilot scale Coal Beneficiation Fluidized Bed (CBFB). The gas and the dense solid phases are modeled using an Eulerian-Eulerian or two fluid model (TFM), while the beneficiated Coal particles are modeled as a dilute phase by the discrete element method (DEM). In this work, the influence of some key operation parameters on particle segregation behavior is studied, including fluidized air velocity, bed depth, and Coal feed ratio and bed medium properties. Their effects are evaluated using a single Coal sample of diameter 4.3 mm. Particles are divided into five different density fractions to represent the wide density range of raw Coal samples. The simulation results demonstrate that by increasing the fluidizing air velocity from 1.2 u mf to 1.8 u mf of the dense medium solids, the segregation degree of beneficiated Coal particles is significantly reduced, but the segregation time is only slightly decreased. Increasing the particle feed mass or decreasing the bed depth has a similar influence on CBFB operation. Both help to improve particle segregation, but a shallower bed is demonstrated to be more effective for Coal Beneficiation. A decrease in the medium density can reduce the bed cut density as well as the Beneficiation limit for lighter samples, while a decrease in the medium size will increase the back-mixing effects, resulting in reduced Beneficiation quality. Hydrodynamic forces acting on the beneficiated particles are also quantified from the simulation results. By analyzing the magnitude and direction of each force acting on discrete particles, the mechanisms influencing particle segregation under different operation conditions are explained at the particle scale.
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numerical study of particle segregation in a Coal Beneficiation fluidized bed by a tfm dem hybrid model influence of Coal particle size and density
Chemical Engineering Journal, 2015Co-Authors: Qinggong Wang, Hairui Yang, Yuqing Feng, Peter J Witt, Weidi Yin, Man ZhangAbstract:Abstract Particle segregation behavior in a Coal Beneficiation fluidized bed (CBFB) is numerically studied using a TFM–DEM hybrid model, in which the gas and the dense solid phases are modeled using a Eulerian–Eulerian or two fluid model (TFM), while the beneficiated Coal particles are modeled as a dilute phase by the discrete element method (DEM). For validation purpose, the numerical model was setup using geometric and operating conditions similar to a laboratory experimental model with the bed thickness set to one particle diameter to save computational cost. For a fixed gas injection velocity, the influence of particle size and density of the beneficiated samples was studied. It was found that the particles would segregate along the bed height due to the density differences with the degree of segregation being strongly influenced by particle size. Obvious segregation occurs for the coarse samples (6.7 mm and 4.3 mm) and little segregation occurs for the particles smaller than 3 mm. The flow patterns and segregation kinetics were qualitatively comparable with those observed in physical experiments conducted under similar conditions. On this basis, the underlying mechanisms governing particle segregation have been explained in terms of the hydrodynamic forces acting on individual particles. It was demonstrated that the segregation of coarse particles was mainly controlled by the balance between gravity and the local pressure force, while fine particles were more strongly affected by the direct drag forces from the gas phase and the continuum solid phase, thus making them difficult to separate.
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The segregation behaviors of fine Coal particles in a Coal Beneficiation fluidized bed
Fuel Processing Technology, 2014Co-Authors: Qinggong Wang, Hairui Yang, Bin Zhao, Weidi Yin, Lubin WeiAbstract:Abstract The segregation behaviors of fine Coal particles in a Coal Beneficiation fluidized bed (CBFB) were investigated in this work. The size range of 1–8 mm was taken into account and three separate size fractions were studied comparatively in the experiments, e.g. 1–2 mm, 3–5.5 mm and 5.5–8 mm. Both a clean Coal sample and a gangue sample were used as the processed material to study the segregation behaviors of both light particles and heavy particles. The dense bed was divided as seven layers from bottom to top and the particle distribution in each layer for each sample was fully demonstrated. The influences of the particle density, particle size and the fluidized air velocity were revealed, the segregation patterns under different conditions were compared and the segregation mechanism was carefully analyzed. The results showed that the flotation and sedimentation of the particles in CBFB were still largely influenced by the particle density for the fine size range particles, and density stratification occurred even within each size fraction sample. The weight fraction in each layer showed a quadratic increase along the bed height for the Coal particles. For gangue particles, a large fraction deposited in the bottom while the mass proportions in the middle layers also showed an increased tendency. With a decrease of the particle size, both the particle segregation and the density stratification phenomena deteriorated seriously. It was proved that particle feed size should be above 3 mm as the separation effect was quite inefficient for finer particles. By increasing the fluidized air velocity, the bed density slightly decreased but the bed turbulence was largely strengthened by the increasing bubble boiling effect. The flotation and sedimentation of the particles in 5.5–8 mm were obviously affected while no clear influence occurred to the rest of the two size fractions. Moreover, the results in this work provide a group of data that are quite suitable for CBFB numerical modeling studies.
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numerical study of gas solid flow in a Coal Beneficiation fluidized bed using kinetic theory of granular flow
Fuel Processing Technology, 2013Co-Authors: Qinggong Wang, Hairui Yang, Weidi Yin, Lubin WeiAbstract:Abstract Modeling the dynamic behavior of gas -solid flow in a pilot scale Coal Beneficiation fluidized bed (CBFB) model was performed in this work, a transient two-dimensional simulation was done based on the Eulerian model together with the kinetic theory of granular flows. Three steps were conducted to testify the choices of sub-models in CBFB modeling, including gas -solid exchange drag models, gas phase turbulence models, granular temperature models and wall boundary condition models for solid phase. Instantaneous and time-averaged results of particle volume fraction, bubble number and size, particle velocity distributions and vortices, as well as bed density distributions were obtained. The impacts of the sub-models on the flow characteristics in the dense CBFB were illustrated in detail and suitable models with better predictions of CBFB flow pattern were then demonstrated. The Syamlal -O'Brien drag model predicted better results in bed characteristics. The dispersed k-e turbulence model should be used to describe the gas turbulence in the dense CBFB flow regime. The partial slip wall condition for particles had a slight influence in the small model. The partial differential equation granular temperature model could predict the inter-phase surfaces more clearly and the flow pattern more accurately.
Lubin Wei - One of the best experts on this subject based on the ideXlab platform.
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numerical study of the effect of operation parameters on particle segregation in a Coal Beneficiation fluidized bed by a tfm dem hybrid model
Chemical Engineering Science, 2015Co-Authors: Qinggong Wang, Hairui Yang, Yuqing Feng, Peter J Witt, Weidi Yin, Qing Liu, Lubin WeiAbstract:Abstract A TFM–DEM hybrid model is introduced for modeling of the complex gas–solid flows in a pilot scale Coal Beneficiation Fluidized Bed (CBFB). The gas and the dense solid phases are modeled using an Eulerian-Eulerian or two fluid model (TFM), while the beneficiated Coal particles are modeled as a dilute phase by the discrete element method (DEM). In this work, the influence of some key operation parameters on particle segregation behavior is studied, including fluidized air velocity, bed depth, and Coal feed ratio and bed medium properties. Their effects are evaluated using a single Coal sample of diameter 4.3 mm. Particles are divided into five different density fractions to represent the wide density range of raw Coal samples. The simulation results demonstrate that by increasing the fluidizing air velocity from 1.2 u mf to 1.8 u mf of the dense medium solids, the segregation degree of beneficiated Coal particles is significantly reduced, but the segregation time is only slightly decreased. Increasing the particle feed mass or decreasing the bed depth has a similar influence on CBFB operation. Both help to improve particle segregation, but a shallower bed is demonstrated to be more effective for Coal Beneficiation. A decrease in the medium density can reduce the bed cut density as well as the Beneficiation limit for lighter samples, while a decrease in the medium size will increase the back-mixing effects, resulting in reduced Beneficiation quality. Hydrodynamic forces acting on the beneficiated particles are also quantified from the simulation results. By analyzing the magnitude and direction of each force acting on discrete particles, the mechanisms influencing particle segregation under different operation conditions are explained at the particle scale.
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The segregation behaviors of fine Coal particles in a Coal Beneficiation fluidized bed
Fuel Processing Technology, 2014Co-Authors: Qinggong Wang, Hairui Yang, Bin Zhao, Weidi Yin, Lubin WeiAbstract:Abstract The segregation behaviors of fine Coal particles in a Coal Beneficiation fluidized bed (CBFB) were investigated in this work. The size range of 1–8 mm was taken into account and three separate size fractions were studied comparatively in the experiments, e.g. 1–2 mm, 3–5.5 mm and 5.5–8 mm. Both a clean Coal sample and a gangue sample were used as the processed material to study the segregation behaviors of both light particles and heavy particles. The dense bed was divided as seven layers from bottom to top and the particle distribution in each layer for each sample was fully demonstrated. The influences of the particle density, particle size and the fluidized air velocity were revealed, the segregation patterns under different conditions were compared and the segregation mechanism was carefully analyzed. The results showed that the flotation and sedimentation of the particles in CBFB were still largely influenced by the particle density for the fine size range particles, and density stratification occurred even within each size fraction sample. The weight fraction in each layer showed a quadratic increase along the bed height for the Coal particles. For gangue particles, a large fraction deposited in the bottom while the mass proportions in the middle layers also showed an increased tendency. With a decrease of the particle size, both the particle segregation and the density stratification phenomena deteriorated seriously. It was proved that particle feed size should be above 3 mm as the separation effect was quite inefficient for finer particles. By increasing the fluidized air velocity, the bed density slightly decreased but the bed turbulence was largely strengthened by the increasing bubble boiling effect. The flotation and sedimentation of the particles in 5.5–8 mm were obviously affected while no clear influence occurred to the rest of the two size fractions. Moreover, the results in this work provide a group of data that are quite suitable for CBFB numerical modeling studies.
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numerical study of gas solid flow in a Coal Beneficiation fluidized bed using kinetic theory of granular flow
Fuel Processing Technology, 2013Co-Authors: Qinggong Wang, Hairui Yang, Weidi Yin, Lubin WeiAbstract:Abstract Modeling the dynamic behavior of gas -solid flow in a pilot scale Coal Beneficiation fluidized bed (CBFB) model was performed in this work, a transient two-dimensional simulation was done based on the Eulerian model together with the kinetic theory of granular flows. Three steps were conducted to testify the choices of sub-models in CBFB modeling, including gas -solid exchange drag models, gas phase turbulence models, granular temperature models and wall boundary condition models for solid phase. Instantaneous and time-averaged results of particle volume fraction, bubble number and size, particle velocity distributions and vortices, as well as bed density distributions were obtained. The impacts of the sub-models on the flow characteristics in the dense CBFB were illustrated in detail and suitable models with better predictions of CBFB flow pattern were then demonstrated. The Syamlal -O'Brien drag model predicted better results in bed characteristics. The dispersed k-e turbulence model should be used to describe the gas turbulence in the dense CBFB flow regime. The partial slip wall condition for particles had a slight influence in the small model. The partial differential equation granular temperature model could predict the inter-phase surfaces more clearly and the flow pattern more accurately.
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Coal dry Beneficiation technology in china: the state-of-the-art
China Particuology, 2003Co-Authors: Qingru Chen, Lubin WeiAbstract:Abstract In China, Coal is the major source of energy and its leading role in energy consumption would not change in the next 50 years. Coal preparation is the essential component of Clean Coal Technology. In China more than two-thirds of available Coal reserves are in arid areas, which results in the unfeasibility with conventional wet processing for Coal preparation. The uniqueness of dry Coal Beneficiation technology with air-dense medium fluidized bed is discussed in this paper and a detailed survey of the current status of theoretical study, commercial application and development of the new technology is given in this paper.
Yuemin Zhao - One of the best experts on this subject based on the ideXlab platform.
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Mixing and segregation behavior in an air dense medium fluidized bed with binary mixtures for dry Coal Beneficiation
Powder Technology, 2020Co-Authors: Jesse Zhu, Shahzad Barghi, Yuemin Zhao, Zhenfu Luo, Chenlong DuanAbstract:Abstract Particle mixing and segregation behavior in an Air Dense Medium Fluidized Bed with binary mixtures of solid particles were investigated for dry Coal Beneficiation. Magnetite mixed with Coal/gangue/sand particles belonging to Geldart B/D group were tested individually for the bed density adjustment. The effects of operating parameters including particle density ratio, particle size ratio, mixture composition, superficial gas velocity, and fluidized bed height on the mixing and segregation pattern were examined. The results demonstrated that the segregation becomes more severe with increasing density difference of binary mixtures. An increase in particle size ratio may also lead to partial segregation. Mixing and segregation of binary systems are almost independent of lower excess gas velocity and initial bed height when it is over 15 cm. Moreover, a mixing index was employed to evaluate the mixing and segregation performance, and the criteria for good mixing to achieve the bed density adjustment were identified.
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dry Coal Beneficiation by the semi industrial air dense medium fluidized bed with binary mixtures of magnetite and fine Coal particles
Fuel, 2019Co-Authors: Zhijie Fu, Shahzad Barghi, Yuemin Zhao, Chenlong DuanAbstract:Abstract Air Dense Medium Fluidized Bed (ADMFB) is deemed to be one of the most efficient methods for dry Coal Beneficiation. In the present work, a semi-industrial ADMFB system in continuous operation was utilized to study the effects of operating gas velocity, feed Coal size, and mixture composition of medium particles on the Coal Beneficiation in industrial practice. Binary mixtures of magnetite and fine Coal particles were used as the medium material, and four different feed Coal samples with the size ranges of −50 + 25, −25 + 13, −13 − 6, and −6 + 2 mm were tested individually. The experimental results showed that the influence of excess gas velocity on the dry Coal separation is relatively small in the lower flow rates. The separation density and probable error increase with the decreasing of feed Coal size, regardless of the type of feed Coal. The separation density can be continually reduced by further increasing the fraction of fine Coal in the medium material, with the compromise of the increased probable error. Moreover, the ash content and calorific value of −50 + 6 mm coarse Coal can be effectively upgraded, but the Beneficiation of −6 + 2 mm fine Coal was less efficient.
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a method to improve fluidization quality in gas solid fluidized bed for fine Coal Beneficiation
Particuology, 2019Co-Authors: Chenyang Zhou, Chenlong Duan, Xuchen Fan, Yuemin ZhaoAbstract:Abstract Dry Coal separation has become essential in China because it does not consume water and it reduces environmental pollution. In this study, a method for improving fluidization quality in a fluidized bed separator using a micropore sponge is proposed. The separator is used for fine Coal Beneficiation. The pressure drop across the distributor and bed fluidization characteristics were analyzed to evaluate fluidization quality. The Beneficiation efficiency for fine Coal was further investigated by using a laboratory-scale fluidized bed with and without a micropore sponge. With the sponge, the highest pressure drop fluctuation factor decreased from 0.23 to 0.16, indicating an improvement in density stability. The modified separation method reduced the ash content of a sample of fine Coal from 23.83% to 10.70%. The probable error efficiency value E for −6 + 3 mm Coal was 0.12 g/cm3, close to the efficiency error values reported for other dry-Beneficiation techniques. The separation results show that using a sponge in the fluidized bed can readily improve the efficiency of fine Coal Beneficiation.
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dry Beneficiation of fine Coal deploying multistage separation processes in a vibrated gas fluidized bed
Separation Science and Technology, 2019Co-Authors: Song Wang, Xuliang Yang, Yu Yang, Yadong Zhang, Yuemin ZhaoAbstract:ABSTRACTIn this study, multistage separation processes were introduced into fine Coal Beneficiation in a vibrated gas-fluidized bed in order to improve the separation performance. The changes of Coal properties, operational parameters, and density segregation characteristics during multistage separation were systematically studied. The results showed that with an increase in the separation stage, the range of density was narrowed down and the required input energy decreased. The results showed that with the same yield, the ash content of clean Coal decreased from 12.53% for single separation stage to 8.91% for three separation stages, indicating a significant improvement on separation accuracy.
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flow pattern transition and Coal Beneficiation in gas solid fluidized bed with novel secondary distributor
Advanced Powder Technology, 2018Co-Authors: Xuchen Fan, Yuemin Zhao, Chenlong Duan, Chenyang Zhou, Qingxia LiuAbstract:Abstract Gas solid fluidized bed (GSFB) is an effective method of dry Coal separation. In this study, porous sponge was introduced into a typical gas solid fluidized bed as secondary air distribution layer (PSFB) to stabilize the fluidized bed layer. The difference between PSFB and GSFB in flow pattern transition process was studied. Compared with GSFB, the minimum gas velocity and bed density fluctuation decreased while bed expansion ratio increased in PSFB. Furthermore, the distribution of bubble phase and emulsion phase were more homogeneous in PSFB. Under the operational conditions, the results of Coal preparation in a PSFB showed that the ash content of clean Coal was 10.25% .The probable error (E) was 0.095 g/cm3, indicating that PSFB could provide a novel way for a good performance of dry coking Coal Beneficiation.
Hairui Yang - One of the best experts on this subject based on the ideXlab platform.
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Numerical study on the effect of fine Coal accumulation in a Coal Beneficiation fluidized bed
Powder Technology, 2015Co-Authors: Qinggong Wang, Junfu Lu, Hairui Yang, Bin ZhaoAbstract:Abstract One important phenomenon in Coal Beneficiation fluidized bed (CBFB) is the accumulation of fine Coal particles in Beneficiation due to poor screening efficiency and attrition of Coal samples. The effect of fine Coal accumulation is numerically studied in this work using a TFM–DEM hybrid model. The gas phase and medium solid phase are modeled by a two-fluid model (TFM), while the fine Coal particles are modeled by the discrete element method (DEM). Particles with a diameter of 0.9 mm are used as the fine Coal sample in the simulation. The gas–solid flow pattern and particle dynamics are investigated with different concentrations of fine Coal particles accumulated in the bed. For model validation purpose, the mean bed density distributions are compared with the experimental reports from He et al. (2013). The results show that a critical particle concentration exists in the fine Coal accumulation process in CBFB. When the fine Coal particles are less than 11 wt% in the bed, the flow pattern of medium phase is little affected and the Coal particles are well mixed in the bed. However, when the particle concentration exceeds this threshold, the uniformity of bed density distribution is destroyed and particle stratification occurs along the bed height according to their density difference. Flow dynamics of the dense bed and main forces acting on the fine Coal particles are analyzed to explain the underlying mechanism. With a large number of particles accumulated in the bed, the mixing effect of medium flow is suppressed. Motion of the fine Coal particles is less dependent on the bed disturbance, instead, the particle gravity plays a decisive role in the particle distribution and results in the particle segregation in the fine Coal accumulation process.
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numerical study of the effect of operation parameters on particle segregation in a Coal Beneficiation fluidized bed by a tfm dem hybrid model
Chemical Engineering Science, 2015Co-Authors: Qinggong Wang, Hairui Yang, Yuqing Feng, Peter J Witt, Weidi Yin, Qing Liu, Lubin WeiAbstract:Abstract A TFM–DEM hybrid model is introduced for modeling of the complex gas–solid flows in a pilot scale Coal Beneficiation Fluidized Bed (CBFB). The gas and the dense solid phases are modeled using an Eulerian-Eulerian or two fluid model (TFM), while the beneficiated Coal particles are modeled as a dilute phase by the discrete element method (DEM). In this work, the influence of some key operation parameters on particle segregation behavior is studied, including fluidized air velocity, bed depth, and Coal feed ratio and bed medium properties. Their effects are evaluated using a single Coal sample of diameter 4.3 mm. Particles are divided into five different density fractions to represent the wide density range of raw Coal samples. The simulation results demonstrate that by increasing the fluidizing air velocity from 1.2 u mf to 1.8 u mf of the dense medium solids, the segregation degree of beneficiated Coal particles is significantly reduced, but the segregation time is only slightly decreased. Increasing the particle feed mass or decreasing the bed depth has a similar influence on CBFB operation. Both help to improve particle segregation, but a shallower bed is demonstrated to be more effective for Coal Beneficiation. A decrease in the medium density can reduce the bed cut density as well as the Beneficiation limit for lighter samples, while a decrease in the medium size will increase the back-mixing effects, resulting in reduced Beneficiation quality. Hydrodynamic forces acting on the beneficiated particles are also quantified from the simulation results. By analyzing the magnitude and direction of each force acting on discrete particles, the mechanisms influencing particle segregation under different operation conditions are explained at the particle scale.
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numerical study of particle segregation in a Coal Beneficiation fluidized bed by a tfm dem hybrid model influence of Coal particle size and density
Chemical Engineering Journal, 2015Co-Authors: Qinggong Wang, Hairui Yang, Yuqing Feng, Peter J Witt, Weidi Yin, Man ZhangAbstract:Abstract Particle segregation behavior in a Coal Beneficiation fluidized bed (CBFB) is numerically studied using a TFM–DEM hybrid model, in which the gas and the dense solid phases are modeled using a Eulerian–Eulerian or two fluid model (TFM), while the beneficiated Coal particles are modeled as a dilute phase by the discrete element method (DEM). For validation purpose, the numerical model was setup using geometric and operating conditions similar to a laboratory experimental model with the bed thickness set to one particle diameter to save computational cost. For a fixed gas injection velocity, the influence of particle size and density of the beneficiated samples was studied. It was found that the particles would segregate along the bed height due to the density differences with the degree of segregation being strongly influenced by particle size. Obvious segregation occurs for the coarse samples (6.7 mm and 4.3 mm) and little segregation occurs for the particles smaller than 3 mm. The flow patterns and segregation kinetics were qualitatively comparable with those observed in physical experiments conducted under similar conditions. On this basis, the underlying mechanisms governing particle segregation have been explained in terms of the hydrodynamic forces acting on individual particles. It was demonstrated that the segregation of coarse particles was mainly controlled by the balance between gravity and the local pressure force, while fine particles were more strongly affected by the direct drag forces from the gas phase and the continuum solid phase, thus making them difficult to separate.
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The segregation behaviors of fine Coal particles in a Coal Beneficiation fluidized bed
Fuel Processing Technology, 2014Co-Authors: Qinggong Wang, Hairui Yang, Bin Zhao, Weidi Yin, Lubin WeiAbstract:Abstract The segregation behaviors of fine Coal particles in a Coal Beneficiation fluidized bed (CBFB) were investigated in this work. The size range of 1–8 mm was taken into account and three separate size fractions were studied comparatively in the experiments, e.g. 1–2 mm, 3–5.5 mm and 5.5–8 mm. Both a clean Coal sample and a gangue sample were used as the processed material to study the segregation behaviors of both light particles and heavy particles. The dense bed was divided as seven layers from bottom to top and the particle distribution in each layer for each sample was fully demonstrated. The influences of the particle density, particle size and the fluidized air velocity were revealed, the segregation patterns under different conditions were compared and the segregation mechanism was carefully analyzed. The results showed that the flotation and sedimentation of the particles in CBFB were still largely influenced by the particle density for the fine size range particles, and density stratification occurred even within each size fraction sample. The weight fraction in each layer showed a quadratic increase along the bed height for the Coal particles. For gangue particles, a large fraction deposited in the bottom while the mass proportions in the middle layers also showed an increased tendency. With a decrease of the particle size, both the particle segregation and the density stratification phenomena deteriorated seriously. It was proved that particle feed size should be above 3 mm as the separation effect was quite inefficient for finer particles. By increasing the fluidized air velocity, the bed density slightly decreased but the bed turbulence was largely strengthened by the increasing bubble boiling effect. The flotation and sedimentation of the particles in 5.5–8 mm were obviously affected while no clear influence occurred to the rest of the two size fractions. Moreover, the results in this work provide a group of data that are quite suitable for CBFB numerical modeling studies.
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numerical study of gas solid flow in a Coal Beneficiation fluidized bed using kinetic theory of granular flow
Fuel Processing Technology, 2013Co-Authors: Qinggong Wang, Hairui Yang, Weidi Yin, Lubin WeiAbstract:Abstract Modeling the dynamic behavior of gas -solid flow in a pilot scale Coal Beneficiation fluidized bed (CBFB) model was performed in this work, a transient two-dimensional simulation was done based on the Eulerian model together with the kinetic theory of granular flows. Three steps were conducted to testify the choices of sub-models in CBFB modeling, including gas -solid exchange drag models, gas phase turbulence models, granular temperature models and wall boundary condition models for solid phase. Instantaneous and time-averaged results of particle volume fraction, bubble number and size, particle velocity distributions and vortices, as well as bed density distributions were obtained. The impacts of the sub-models on the flow characteristics in the dense CBFB were illustrated in detail and suitable models with better predictions of CBFB flow pattern were then demonstrated. The Syamlal -O'Brien drag model predicted better results in bed characteristics. The dispersed k-e turbulence model should be used to describe the gas turbulence in the dense CBFB flow regime. The partial slip wall condition for particles had a slight influence in the small model. The partial differential equation granular temperature model could predict the inter-phase surfaces more clearly and the flow pattern more accurately.
Chenlong Duan - One of the best experts on this subject based on the ideXlab platform.
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Mixing and segregation behavior in an air dense medium fluidized bed with binary mixtures for dry Coal Beneficiation
Powder Technology, 2020Co-Authors: Jesse Zhu, Shahzad Barghi, Yuemin Zhao, Zhenfu Luo, Chenlong DuanAbstract:Abstract Particle mixing and segregation behavior in an Air Dense Medium Fluidized Bed with binary mixtures of solid particles were investigated for dry Coal Beneficiation. Magnetite mixed with Coal/gangue/sand particles belonging to Geldart B/D group were tested individually for the bed density adjustment. The effects of operating parameters including particle density ratio, particle size ratio, mixture composition, superficial gas velocity, and fluidized bed height on the mixing and segregation pattern were examined. The results demonstrated that the segregation becomes more severe with increasing density difference of binary mixtures. An increase in particle size ratio may also lead to partial segregation. Mixing and segregation of binary systems are almost independent of lower excess gas velocity and initial bed height when it is over 15 cm. Moreover, a mixing index was employed to evaluate the mixing and segregation performance, and the criteria for good mixing to achieve the bed density adjustment were identified.
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dry Coal Beneficiation by the semi industrial air dense medium fluidized bed with binary mixtures of magnetite and fine Coal particles
Fuel, 2019Co-Authors: Zhijie Fu, Shahzad Barghi, Yuemin Zhao, Chenlong DuanAbstract:Abstract Air Dense Medium Fluidized Bed (ADMFB) is deemed to be one of the most efficient methods for dry Coal Beneficiation. In the present work, a semi-industrial ADMFB system in continuous operation was utilized to study the effects of operating gas velocity, feed Coal size, and mixture composition of medium particles on the Coal Beneficiation in industrial practice. Binary mixtures of magnetite and fine Coal particles were used as the medium material, and four different feed Coal samples with the size ranges of −50 + 25, −25 + 13, −13 − 6, and −6 + 2 mm were tested individually. The experimental results showed that the influence of excess gas velocity on the dry Coal separation is relatively small in the lower flow rates. The separation density and probable error increase with the decreasing of feed Coal size, regardless of the type of feed Coal. The separation density can be continually reduced by further increasing the fraction of fine Coal in the medium material, with the compromise of the increased probable error. Moreover, the ash content and calorific value of −50 + 6 mm coarse Coal can be effectively upgraded, but the Beneficiation of −6 + 2 mm fine Coal was less efficient.
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a method to improve fluidization quality in gas solid fluidized bed for fine Coal Beneficiation
Particuology, 2019Co-Authors: Chenyang Zhou, Chenlong Duan, Xuchen Fan, Yuemin ZhaoAbstract:Abstract Dry Coal separation has become essential in China because it does not consume water and it reduces environmental pollution. In this study, a method for improving fluidization quality in a fluidized bed separator using a micropore sponge is proposed. The separator is used for fine Coal Beneficiation. The pressure drop across the distributor and bed fluidization characteristics were analyzed to evaluate fluidization quality. The Beneficiation efficiency for fine Coal was further investigated by using a laboratory-scale fluidized bed with and without a micropore sponge. With the sponge, the highest pressure drop fluctuation factor decreased from 0.23 to 0.16, indicating an improvement in density stability. The modified separation method reduced the ash content of a sample of fine Coal from 23.83% to 10.70%. The probable error efficiency value E for −6 + 3 mm Coal was 0.12 g/cm3, close to the efficiency error values reported for other dry-Beneficiation techniques. The separation results show that using a sponge in the fluidized bed can readily improve the efficiency of fine Coal Beneficiation.
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flow pattern transition and Coal Beneficiation in gas solid fluidized bed with novel secondary distributor
Advanced Powder Technology, 2018Co-Authors: Xuchen Fan, Yuemin Zhao, Chenlong Duan, Chenyang Zhou, Qingxia LiuAbstract:Abstract Gas solid fluidized bed (GSFB) is an effective method of dry Coal separation. In this study, porous sponge was introduced into a typical gas solid fluidized bed as secondary air distribution layer (PSFB) to stabilize the fluidized bed layer. The difference between PSFB and GSFB in flow pattern transition process was studied. Compared with GSFB, the minimum gas velocity and bed density fluctuation decreased while bed expansion ratio increased in PSFB. Furthermore, the distribution of bubble phase and emulsion phase were more homogeneous in PSFB. Under the operational conditions, the results of Coal preparation in a PSFB showed that the ash content of clean Coal was 10.25% .The probable error (E) was 0.095 g/cm3, indicating that PSFB could provide a novel way for a good performance of dry coking Coal Beneficiation.
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industrial application of a modularized dry Coal Beneficiation technique based on a novel air dense medium fluidized bed
International Journal of Coal Preparation and Utilization, 2017Co-Authors: Yuemin Zhao, Zhenfu Luo, Bo Zhang, Liang Dong, Chuncheng Liang, Chenlong DuanAbstract:ABSTRACTCoal is one of the most important primary energy sources all over the world. One of the clean-Coal technologies is Coal preparation, and dry-Coal Beneficiation plays an increasingly important role with an increasing shortage of water. A novel air dense medium fluidized bed (ADMFB) separator developed by the China University of Mining and Technology, with magnetic powder and fine Coal acting as the heavy medium, has the advantages of uniform and stable bed density, low cost, and high reliability. The world’s first modularized dry-Coal Beneficiation based on the novel ADMFB was established, realizing the industrial application of ADMFB separation technology. The industrial application showed that the ash content of Coal decreased to 3.46% with an ash rejection of 85.57%, the yield of clean Coal was 67.88%, the probable error (E value) was 0.055 g/cm3, the organic efficiency was 93%, and the heavy-medium loss when separating one ton of Coal was 0.42 kg. Less than $2 was spent for separating one ton o...