The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Haim Kalman - One of the best experts on this subject based on the ideXlab platform.
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Simplified model for Particle collision related to Attrition in pneumatic conveying
Advanced Powder Technology, 2020Co-Authors: Dmitry Portnikov, Nir Santo, Haim KalmanAbstract:Abstract This paper presents a simple method for predicting Particle Attrition during pneumatic conveying. The model calculates the changes in the Particle size during pneumatic conveying (as a result of the collisions between the Particles and bend walls) by using empirical correlations for both the machine and material functions. The method does not require the use of complicated simulations such as DEM–CFD. Furthermore, the computational model was written in MATLAB, and the results agree well with the experimental results for salt Particles. The computation time was very short: a few seconds for the first collision (Particles passed through one bend), and below one minute for six collisions. The experimental results and parametric study show that higher bend radius ratios caused less damage to the conveyed material. Moreover, higher air velocities and larger pipe diameters caused more damage to the conveyed material.
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A novel Particle Attrition model for conveying systems
Powder Technology, 2016Co-Authors: Avi Uzi, Haim Kalman, Avi LevyAbstract:Abstract The ability to forecast how a conveying system will operate prior to its construction is a major issue for both industry and research. A trustworthy prediction can assist in the design of a conveying system and save efforts and resources spent in trial and error. In the present study, a novel model is presented for predicting the size reduction of Particles coupled with the flow field in pipeline conveying. The model consists of two parts: a one-dimensional two-phase model that calculates the flow field and a one-dimensional breakage algorithm that accounts for Particle collisions and breakage. The breakage algorithm exploits both empirical comminution functions defining the Particle characteristics and machine functions (impact velocity and collision frequency) defining the system behavior, which are developed from CFD-DEM simulations. In the breakage model, the Particles are described as individual discrete entities within a representative mass. This approach facilitates the use of low computational resources in the prediction of Particle size reduction in conveying systems, thereby making it especially applicable for long-range industrial pipelines. Furthermore, in this method, it is possible to take into account Particle fatigue and Attrition not only in straight pipe sections but also in bends. In the current study, our new breakage model was implemented in a dilute-phase pneumatic conveying system. The machine functions developed for this system showed the following clear tendencies: Finer Particles collide with the pipe wall at higher impact velocities and higher frequencies, while Particle-Particle interactions occur more frequently for coarser Particles. Furthermore, it was found that breakage due to Particle-Particle interactions was significant inside bend elements, thereby implying that these collisions cannot be neglected. The model predictions of Particle Attrition were in good agreement, with a mean deviation of 5.8%, with the breakage results obtained previously by our group in dilute-phase pneumatic conveying experiments.
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DEM simulation of Particle Attrition in dilute-phase pneumatic conveying
Granular Matter, 2011Co-Authors: Tamir Brosh, Haim Kalman, Avi LevyAbstract:Three dimensional numerical simulations of Particles motion in a given geometry pneumatic conveying system are conducted in order to obtain a better understanding of the Attrition process. A new and innovative procedure of implementing empirical comminution functions (Kalman et al. in Gran Mat 11:253–266, 2009) into DEM-CFD simulations was used and modified. The comminution functions include: initial strength distribution, selection function, breakage function, equivalence function and fatigue function. The implementation involves converting the probability comminution functions into individual Particle properties by a random method and then converting the velocity dependent comminution functions into strength-dependent ones. The predictions of the numerical simulations are used to analyze the flow field characteristics and the size reduction process.
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Fatigue analysis of Particle Attrition in a rotating drum
Particle and Particle Systems Characterization, 2001Co-Authors: Evgeny Grant, Haim KalmanAbstract:Rotating drums are commonly used as grinders by inserting balls or rods into the drum. They are also employed as a standard measurement device for Attrition and friability, mainly in the pharmaceutical industry. This paper presents a phenomenological study of the behavior of rotating drums and the fatigue phenomenon. A sensitivity test showed that for potash the drum should rotate at 30 rpm and the sample weight should be 100 g, so as to maximize the Attrition rate. Further experimentation showed that the crush strength of the surviving Particles changes significantly during the test owing to fatigue.
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Design criteria for Particle Attrition
Advanced Powder Technology, 1998Co-Authors: Haim Kalman, D. GoderAbstract:Attrition and comminution are major effects that occur in handling and conveying systems of particulate solids. However, appropriate design tools based on reliable and significant bulk solids' properties are not available. In this paper we outline some preliminary steps and ideas to obtain such tools (by similarity to the design of solid machine parts). Furthermore, we show that particulate systems are damaged by constant as well as cyclic loads. In this sense most existing experimental systems could be analyzed and compared. The results gained by a new fatigue machine show clearly the effect of fatigue in compression up to 25 000 cycles of loading. By introducing systems in which the strength properties of either single Particles or particulate systems could be defined, their behavior is characterized. Moreover, two examples are analyzed: a rotary drum and a pneumatic conveying pipe line (in very dilute states). Both systems are actually affected by the same phenomenon (fatigue) at various ranges of loads.
Jennifer Mcmillan - One of the best experts on this subject based on the ideXlab platform.
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Particle Attrition with supersonic nozzles in a fluidized bed at high temperature
Powder Technology, 2012Co-Authors: Cedric Briens, Franco Berruti, Jennifer McmillanAbstract:Abstract Fluidized beds are used for a variety of processes such as food, pharmaceutical, petrochemical and energy production. Supersonic gas injection nozzles are used to grind Particles in fluidized beds. For example, in the Fluid Coking process, which uses thermal cracking reactions to upgrade heavy oil, supersonic nozzles inject steam to control coke Particle size. Maintaining a high Attrition rate with a lower steam flowrate would reduce energy consumption, increase reactor throughput, and reduce sour wastewater production. The purpose of the present research is to study Particle Attrition with supersonic convergent–divergent nozzles in a fluidized bed at high temperatures, under conditions such as those encountered in the Fluid Coking process. According to the experimental results, the grinding efficiency is significantly improved by increasing fluidized bed temperature, Attrition gas properties, or nozzle size. The experimental data further suggest that Particle fragmentation is the dominant Attrition process when using supersonic nozzles in a hot fluidized bed.
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Jet Attrition in a fluidized bed. Part II: Effect of fluidized bed hydrodynamics
Powder Technology, 2012Co-Authors: Qi Zhang, Franco Berruti, Cedric Briens, Tarek J. Jamaleddine, Jennifer McmillanAbstract:Abstract The effect of fluidized bed hydrodynamics on jet Attrition with a supersonic Attrition nozzle has been studied in this paper. The aim is to determine a hydrodynamic condition that can help improve Particle Attrition. Two hydrodynamic zones were created by a specially designed fluidized bed. Experiments were conducted with a supersonic Attrition jet either straddling both hydrodynamic zones, or completely enclosed within one hydrodynamic zone. It is found that jet grinding is most effective when the nozzle tip is located in a high fluidization velocity region and jet tip located in a low fluidization velocity region. Also, a larger nozzle is more effective in terms of the new surface area created. A baffle is found to improve the jet Attrition process when it was inserted underneath the jet tip cavity.
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Nozzle design influence on Particle Attrition by a supersonic steam jet
Powder Technology, 2011Co-Authors: Konstantin Pougatch, Martha Salcudean, Jennifer McmillanAbstract:Abstract This paper presents an extension of a mathematical model for Particle Attrition inside a fluidized bed by a supersonic air jet and its application to optimize the nozzle design. A new method to calculate grinding efficiency is presented. Also, heat transfer is included in the model because of the large interfacial temperature difference. Numerical simulations are conducted to investigate various nozzle designs, i.e. a range of area ratios (indicative of the jet being over- or under-expanded) and nozzle expansion angles, and different bed fluidization velocities. It is found that the perfectly expanded nozzle (the exit pressure equal to the outside pressure) provides better Attrition performance than over- and under-expanded jets. The nozzle expansion angle also has an influence on the grinding efficiency: narrow angled nozzles have higher grinding efficiency. In addition, the analysis of various bed fluidization velocities indicates that increasing the velocity results in a modest improvement of the grinding efficiency.
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Simulation of Particle Attrition by supersonic gas jets in fluidized beds
Chemical Engineering Science, 2010Co-Authors: Konstantin Pougatch, Martha Salcudean, Jennifer McmillanAbstract:Abstract Particle breakage by gas jet is encountered in many processes. Quite often it is necessary to evaluate the Attrition performance of different equipment configurations at various flow conditions. Therefore, a simulation tool that can be applied for industrial scale devices can be very beneficial for process design and optimization. A mathematical model for Particle Attrition by high velocity gas jets is developed. The model utilizes an Eulerian–Eulerian approach for the gaseous and particulate phases coupled with the kinetic theory of granular flow and a novel Attrition model connecting the solid phase properties and the granular temperature with the breakage rate. Modelling results allow the calculation of the grinding efficiency – a quantitative measure of the Attrition performance. For validation purposes, the model is applied to a large number of cases that have been investigated experimentally. Simulation results demonstrate that the increase of the nozzle inlet pressure or the exit diameter for a forward step nozzle produces an increase of the grinding efficiency. In addition, the convergent–divergent nozzle is more efficient in breaking the Particles than the nozzle that contains only the convergent section.
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Study of High Velocity Attrition Nozzles in a Fluidized Bed
2007Co-Authors: Jennifer Mcmillan, Cedric Briens, Franco Berruti, Edward ChanAbstract:The objective of this study was to test different high velocity Attrition nozzles and operating conditions in order to determine the effects of various parameters on the grinding efficiency. Nozzle geometry, as well as gas properties such as speed of sound and density had a significant impact on the grinding efficiency. In addition, a model was developed in order to understand the Particle breakage mechanisms during Particle Attrition. The model showed that the primary Attrition mechanism was the splitting of Particles rather than their erosion.
Yolanda A Criado - One of the best experts on this subject based on the ideXlab platform.
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Kinetics of the CaO/Ca(OH)2 Hydration/Dehydration Reaction for Thermochemical Energy Storage Applications
Industrial & Engineering Chemistry Research, 2014Co-Authors: Yolanda A Criado, M Alonso, J. Carlos AbanadesAbstract:The calcium oxide hydration/dehydration reaction is proposed as a suitable reaction couple for thermochemical energy storage systems. However, limited work has been reported on the reaction kinetics of CaO/Ca(OH)2 under appropriate operation conditions for storage applications involving fluidized beds. This study focuses on the effect of temperature, partial steam pressure, and Particle size upon the intrinsic hydration and dehydration reaction kinetics when natural materials are used. The experimental data have been fitted satisfactorily to a shrinking core model for both hydration and dehydration reactions, at reaction temperatures between 400 and 560 °C and partial steam pressures between 0 and 100 kPa. The reaction rates measured are higher than those previously reported in the literature. In the case of large Particle sizes of natural material, Particle Attrition has been detected indicating the need to develop more suitable materials for thermochemical energy storage applications.
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kinetics of the cao ca oh 2 hydration dehydration reaction for thermochemical energy storage applications
Industrial & Engineering Chemistry Research, 2014Co-Authors: Yolanda A Criado, M Alonso, Carlos J AbanadesAbstract:The calcium oxide hydration/dehydration reaction is proposed as a suitable reaction couple for thermochemical energy storage systems. However, limited work has been reported on the reaction kinetics of CaO/Ca(OH)2 under appropriate operation conditions for storage applications involving fluidized beds. This study focuses on the effect of temperature, partial steam pressure, and Particle size upon the intrinsic hydration and dehydration reaction kinetics when natural materials are used. The experimental data have been fitted satisfactorily to a shrinking core model for both hydration and dehydration reactions, at reaction temperatures between 400 and 560 °C and partial steam pressures between 0 and 100 kPa. The reaction rates measured are higher than those previously reported in the literature. In the case of large Particle sizes of natural material, Particle Attrition has been detected indicating the need to develop more suitable materials for thermochemical energy storage applications.
Carlos J Abanades - One of the best experts on this subject based on the ideXlab platform.
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kinetics of the cao ca oh 2 hydration dehydration reaction for thermochemical energy storage applications
Industrial & Engineering Chemistry Research, 2014Co-Authors: Yolanda A Criado, M Alonso, Carlos J AbanadesAbstract:The calcium oxide hydration/dehydration reaction is proposed as a suitable reaction couple for thermochemical energy storage systems. However, limited work has been reported on the reaction kinetics of CaO/Ca(OH)2 under appropriate operation conditions for storage applications involving fluidized beds. This study focuses on the effect of temperature, partial steam pressure, and Particle size upon the intrinsic hydration and dehydration reaction kinetics when natural materials are used. The experimental data have been fitted satisfactorily to a shrinking core model for both hydration and dehydration reactions, at reaction temperatures between 400 and 560 °C and partial steam pressures between 0 and 100 kPa. The reaction rates measured are higher than those previously reported in the literature. In the case of large Particle sizes of natural material, Particle Attrition has been detected indicating the need to develop more suitable materials for thermochemical energy storage applications.
J. Carlos Abanades - One of the best experts on this subject based on the ideXlab platform.
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Kinetics of the CaO/Ca(OH)2 Hydration/Dehydration Reaction for Thermochemical Energy Storage Applications
Industrial & Engineering Chemistry Research, 2014Co-Authors: Yolanda A Criado, M Alonso, J. Carlos AbanadesAbstract:The calcium oxide hydration/dehydration reaction is proposed as a suitable reaction couple for thermochemical energy storage systems. However, limited work has been reported on the reaction kinetics of CaO/Ca(OH)2 under appropriate operation conditions for storage applications involving fluidized beds. This study focuses on the effect of temperature, partial steam pressure, and Particle size upon the intrinsic hydration and dehydration reaction kinetics when natural materials are used. The experimental data have been fitted satisfactorily to a shrinking core model for both hydration and dehydration reactions, at reaction temperatures between 400 and 560 °C and partial steam pressures between 0 and 100 kPa. The reaction rates measured are higher than those previously reported in the literature. In the case of large Particle sizes of natural material, Particle Attrition has been detected indicating the need to develop more suitable materials for thermochemical energy storage applications.