The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
Ying Wang - One of the best experts on this subject based on the ideXlab platform.
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gas solid flow behaviour prediction for sand in bypass pneumatic conveying with conventional frictional kinetic model
Applied Mathematical Modelling, 2016Co-Authors: K C Williams, Ying Wang, Bin ChenAbstract:Abstract Bypass pneumatic conveying is an alternative way to convey Material which does not have dense phase transport capability. The computational fluid dynamics based commercial software Fluent 6.3 is used to investigate the pressure drop as well as the gas–solid flow behaviour in a bypass pneumatic conveying system. The Conveyed Material was sand with a mean particle size of 378 µm and the solid loading ratio was in the range of 10–123. The conventional frictional-kinetic model combining frictional and kinetic stresses simultaneously was applied for pressure drop prediction. The simulation results were then compared with experimental results from bypass pneumatic conveying tests. Selected image results from the computational fluid dynamics simulations were utilised and compared with images captured from high speed camera. In addition, a test case with low air mass flow rate and high solid loading ratio 82.49 was chosen as an example to show detailed gas–solid flow behaviour in the simulation of highly dense flows. It was found that conventional frictional-kinetic model with modified packing limit and friction packing limit has greatly improved the pressure drop prediction result compared with kinetic theory without friction. The detailed analysis for the selected test case showed how the full bore dune formation and deformation of sand and bypass flutes interact. High amplitude fluctuations and variation in pressure and gas velocity were observed. The gas velocity vectors indicate a high degree of air penetration from the flute into the bypass pipe. This behaviour provides an aeration mechanism which is what makes the bypass system work and allows non-dense phase Material to be Conveyed in a dense mode of flow.
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Gas–solid flow behaviour prediction for sand in bypass pneumatic conveying with conventional frictional-kinetic model
Applied Mathematical Modelling, 2016Co-Authors: Ying Wang, Kenneth Williams, Bin ChenAbstract:Abstract Bypass pneumatic conveying is an alternative way to convey Material which does not have dense phase transport capability. The computational fluid dynamics based commercial software Fluent 6.3 is used to investigate the pressure drop as well as the gas–solid flow behaviour in a bypass pneumatic conveying system. The Conveyed Material was sand with a mean particle size of 378 µm and the solid loading ratio was in the range of 10–123. The conventional frictional-kinetic model combining frictional and kinetic stresses simultaneously was applied for pressure drop prediction. The simulation results were then compared with experimental results from bypass pneumatic conveying tests. Selected image results from the computational fluid dynamics simulations were utilised and compared with images captured from high speed camera. In addition, a test case with low air mass flow rate and high solid loading ratio 82.49 was chosen as an example to show detailed gas–solid flow behaviour in the simulation of highly dense flows. It was found that conventional frictional-kinetic model with modified packing limit and friction packing limit has greatly improved the pressure drop prediction result compared with kinetic theory without friction. The detailed analysis for the selected test case showed how the full bore dune formation and deformation of sand and bypass flutes interact. High amplitude fluctuations and variation in pressure and gas velocity were observed. The gas velocity vectors indicate a high degree of air penetration from the flute into the bypass pipe. This behaviour provides an aeration mechanism which is what makes the bypass system work and allows non-dense phase Material to be Conveyed in a dense mode of flow.
Bin Chen - One of the best experts on this subject based on the ideXlab platform.
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gas solid flow behaviour prediction for sand in bypass pneumatic conveying with conventional frictional kinetic model
Applied Mathematical Modelling, 2016Co-Authors: K C Williams, Ying Wang, Bin ChenAbstract:Abstract Bypass pneumatic conveying is an alternative way to convey Material which does not have dense phase transport capability. The computational fluid dynamics based commercial software Fluent 6.3 is used to investigate the pressure drop as well as the gas–solid flow behaviour in a bypass pneumatic conveying system. The Conveyed Material was sand with a mean particle size of 378 µm and the solid loading ratio was in the range of 10–123. The conventional frictional-kinetic model combining frictional and kinetic stresses simultaneously was applied for pressure drop prediction. The simulation results were then compared with experimental results from bypass pneumatic conveying tests. Selected image results from the computational fluid dynamics simulations were utilised and compared with images captured from high speed camera. In addition, a test case with low air mass flow rate and high solid loading ratio 82.49 was chosen as an example to show detailed gas–solid flow behaviour in the simulation of highly dense flows. It was found that conventional frictional-kinetic model with modified packing limit and friction packing limit has greatly improved the pressure drop prediction result compared with kinetic theory without friction. The detailed analysis for the selected test case showed how the full bore dune formation and deformation of sand and bypass flutes interact. High amplitude fluctuations and variation in pressure and gas velocity were observed. The gas velocity vectors indicate a high degree of air penetration from the flute into the bypass pipe. This behaviour provides an aeration mechanism which is what makes the bypass system work and allows non-dense phase Material to be Conveyed in a dense mode of flow.
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Gas–solid flow behaviour prediction for sand in bypass pneumatic conveying with conventional frictional-kinetic model
Applied Mathematical Modelling, 2016Co-Authors: Ying Wang, Kenneth Williams, Bin ChenAbstract:Abstract Bypass pneumatic conveying is an alternative way to convey Material which does not have dense phase transport capability. The computational fluid dynamics based commercial software Fluent 6.3 is used to investigate the pressure drop as well as the gas–solid flow behaviour in a bypass pneumatic conveying system. The Conveyed Material was sand with a mean particle size of 378 µm and the solid loading ratio was in the range of 10–123. The conventional frictional-kinetic model combining frictional and kinetic stresses simultaneously was applied for pressure drop prediction. The simulation results were then compared with experimental results from bypass pneumatic conveying tests. Selected image results from the computational fluid dynamics simulations were utilised and compared with images captured from high speed camera. In addition, a test case with low air mass flow rate and high solid loading ratio 82.49 was chosen as an example to show detailed gas–solid flow behaviour in the simulation of highly dense flows. It was found that conventional frictional-kinetic model with modified packing limit and friction packing limit has greatly improved the pressure drop prediction result compared with kinetic theory without friction. The detailed analysis for the selected test case showed how the full bore dune formation and deformation of sand and bypass flutes interact. High amplitude fluctuations and variation in pressure and gas velocity were observed. The gas velocity vectors indicate a high degree of air penetration from the flute into the bypass pipe. This behaviour provides an aeration mechanism which is what makes the bypass system work and allows non-dense phase Material to be Conveyed in a dense mode of flow.
David Mills - One of the best experts on this subject based on the ideXlab platform.
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System selection considerations
Pneumatic Conveying Design Guide, 2016Co-Authors: David MillsAbstract:The selection of a pneumatic conveying system for a particular application involves the consideration of numerous parameters associated with the Conveyed Material, the conveying conditions, and the system itself. The basic specification is usually that a Material should be Conveyed at a specified flow rate over a given distance. For any given situation, a wide combination of pipeline bores and conveying line pressure drop values are usually available that adequately meet the requirements. Therefore, there is rarely a problem of not being able to achieve a given duty; however, getting it right the first time is a common problem. Power consumption and hence system-operating costs are an obvious factor in the decision-making process. Furthermore, when selecting a pneumatic conveying system for a particular application, it is generally the conveying potential of the system that is of primary importance. The number of factors that have a potential influence on Material flow rate is quite considerable. They can be grouped into three broad categories: those associated with the Conveyed Material, the conveying conditions, and the pipeline geometry.
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Chapter 18 – Stepped Pipelines
Pneumatic Conveying Design Guide, 2016Co-Authors: David MillsAbstract:The use of stepped pipelines are to be recommended in any positive-pressure pneumatic conveying system where the air supply pressure is above about 0.8 bar gauge and in any vacuum conveying system where the operating vacuum is below about 0.4 bar. It can almost be guaranteed that a stepped pipeline will convey Material at a higher rate than the equivalent single-bore line and this applies to vacuum conveying systems as well as positive pressure. In some of the cases reported here, the improvement in conveying performance has been of the order of 100%. Significant reductions in conveying air velocity values can be achieved and this of particular advantage if the Conveyed Material is either abrasive or friable. Reference is also made to alternative air-extraction systems, which are generally applied to single-bore pipelines, and it is shown that an improvement in conveying performance can be achieved even when more than half of the original conveying air is discharged before the end of the pipeline.
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Chapter 11 – Conveying Characteristics
Pneumatic Conveying Design Guide, 2016Co-Authors: David MillsAbstract:In this chapter bulk particulate Materials are added to the air in the pipeline and the influence on the resulting conveying-line pressure drop is illustrated. Conveying air velocities and solids loading ratios are evaluated and the conveying limits are established for the different types of Conveyed Material. Data are presented on a number of powdered and granular Materials and it is shown how the properties of the Materials influence their conveying capability. The analysis is then extended to show how different conveying conditions can influence the power requirements for conveying Materials. This is further developed to evaluate specific energy data so that the economics of pneumatic conveying can be compared with alternative mechanical means of conveying. Individual elements of the pipeline are also examined to show how vertically up and vertically down sections of pipeline, as well as bends, compare with horizontal pipeline in the overall performance of a pneumatic conveying system.
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General Operating Problems
Pneumatic Conveying Design Guide, 2016Co-Authors: David MillsAbstract:In this chapter a very broad range of possible operating problems are considered that are very specific to particular types of system and to common system components. These include the use of backup filters, the problem of air ingress and air loss in systems, and the control of feed rate. Positive- and negative-pressure systems, combined systems, and single-plug systems are all included in the analysis. Blowers, blow tanks, rotary valves, filters, and vacuum nozzles are all identified as system components that need particular consideration. Specific problems that tend to be overlooked are also included, such as the influence of altitude, gradual plant wear, pipeline purging, and temperature variations with regard to both Conveyed Material and conveying air. Seasonal variations resulting from changes in both humidity and temperature are also considered. By way of introduction to the chapters that follow, specific problems relating to component wear, degradation of Conveyed Materials, and the possibilities of an explosion are also considered.
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Chapter 8 – System selection considerations
Pneumatic Conveying Design Guide, 2004Co-Authors: David MillsAbstract:Publisher Summary The selection of a pneumatic conveying system for a particular application involves the consideration of numerous parameters associated with the Conveyed Material, the conveying conditions, and the system itself. The basic specification is usually that a Material should be Conveyed at a specified flow rate over a given distance. For any given situation, a wide combination of pipeline bores and conveying line pressure drop values are usually available that adequately meet the requirements. Therefore, there is rarely a problem of not being able to achieve a given duty; however, getting it right the first time is a common problem. Power consumption and hence system-operating costs are an obvious factor in the decision-making process. Furthermore, when selecting a pneumatic conveying system for a particular application, it is generally the conveying potential of the system that is of primary importance. The number of factors that have a potential influence on Material flow rate is quite considerable. They can be grouped into three broad categories: those associated with the Conveyed Material, the conveying conditions, and the pipeline geometry.
Kenneth Williams - One of the best experts on this subject based on the ideXlab platform.
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Gas–solid flow behaviour prediction for sand in bypass pneumatic conveying with conventional frictional-kinetic model
Applied Mathematical Modelling, 2016Co-Authors: Ying Wang, Kenneth Williams, Bin ChenAbstract:Abstract Bypass pneumatic conveying is an alternative way to convey Material which does not have dense phase transport capability. The computational fluid dynamics based commercial software Fluent 6.3 is used to investigate the pressure drop as well as the gas–solid flow behaviour in a bypass pneumatic conveying system. The Conveyed Material was sand with a mean particle size of 378 µm and the solid loading ratio was in the range of 10–123. The conventional frictional-kinetic model combining frictional and kinetic stresses simultaneously was applied for pressure drop prediction. The simulation results were then compared with experimental results from bypass pneumatic conveying tests. Selected image results from the computational fluid dynamics simulations were utilised and compared with images captured from high speed camera. In addition, a test case with low air mass flow rate and high solid loading ratio 82.49 was chosen as an example to show detailed gas–solid flow behaviour in the simulation of highly dense flows. It was found that conventional frictional-kinetic model with modified packing limit and friction packing limit has greatly improved the pressure drop prediction result compared with kinetic theory without friction. The detailed analysis for the selected test case showed how the full bore dune formation and deformation of sand and bypass flutes interact. High amplitude fluctuations and variation in pressure and gas velocity were observed. The gas velocity vectors indicate a high degree of air penetration from the flute into the bypass pipe. This behaviour provides an aeration mechanism which is what makes the bypass system work and allows non-dense phase Material to be Conveyed in a dense mode of flow.
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Numerical study on pressure prediction and its main influence factors in pneumatic conveyors
Chemical Engineering Science, 2010Co-Authors: Kenneth Williams, Jiemin Zhou, Mark JonesAbstract:Abstract The flow characteristics of multiphase gas–solid flow in a pneumatic conveyor were investigated numerically and experimentally to predict the important pressure within the pipeline. The effects of particle size, particle density, and bend radius ratio on pressure drop over the bend pipeline were also analysed. Experiments were conducted to obtain the static pressure at certain cross-sections of a fine powder pneumatic conveying pipeline with a length of 26 m and an inner diameter of 53 mm. The Conveyed Material was flyash with a mean particle size of 30 μm and the solids loading ratio was in the range 20–70. A numerical study of gas–solid flow in complex three-dimensional systems was undertaken by means of commercial CFD software Fluent 6.3. The simulation was performed using the Euler–Euler approach, accounting for four-way coupling. The calculated results of pressure gradient were found to be in good agreement with the measured data, with a fitting slope of 0.781 for the first horizontal straight pipeline and 1.017 for horizontal bend. It was also found that the pressure gradients increase with increase in particle diameter rapidly and reach the peak value when particle diameter is 150 μm, and then begin to decrease and show a slight steepening with increase in particle diameter with a value greater than 150 μm. An increase in particle density results in increase in pressure gradient. The pressure drop is much smaller when the roughness height is zero. The pressure gradient over the horizontal bend increases gradually with the increase of roughness height. The larger the roughness constant is defined, the greater the pressure drop will be. The bend pressure gradient decreases significantly when the bend radius ratio increases from 1 to 3, and then much slowly for bend radius ratios 3–6. With the increase of velocity difference, the pressure drop decrease is different at first, after 0.2–0.3 m, the pressure reduces the same.
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Numerical simulation study on sensitivity of pressure drop predicting in pneumatic transport with various settings
2009Co-Authors: Kenneth Williams, Jiemin Zhou, Mark JonesAbstract:The sensitivity of pressure drop predicting in pneumatic transport with different settings were investigated numerically by means of the commercial CFD software Fluent. The simulation was performed by the Euler-Euler approach accounting for four-way coupling. The pressure drops between certain cross-sections of a pneumatic conveying pipeline with a length of 26m and an inner diameter of 53 mm were predicted based on a series of experiments. The Conveyed Material was flyash with a mean particle size of 30 micron and the solids loading ratios was in the range of about 20 to 70. The agreement of the predictions with the experiments was found to be very good. Furthermore, the effect of various CFD settings on the pressure drops was investigated systematically. It was found that models for solids shear viscosity, solids pressure, radial distribution and drag coefficient have little effect on pressure drop predictions, and viscous model for different turbulence models has a little larger influence on pressure drop in comparison. The most sensitive variables are related to wall shear conditions. The sensitivity of pressure drop predicting in pneumatic transport with different settings were investigated numerically by means of the commercial CFD software Fluent. The simulation was performed by the Euler-Euler approach accounting for four-way coupling. The pressure drops between certain cross-sections of a pneumatic conveying pipeline with a length of 26 m and an inner diameter of 53 mm were predicted based on a series of experiments. The Conveyed Material was flyash with a mean particle size of 30 micron and the solids loading ratios was in the range of about 20 to 70. The agreement of the predictions with the experiments was found to be very good. Furthermore, the effect of various CFD settings on the pressure drops was investigated systematically. It was found that models for solids shear viscosity, solids pressure, radial distribution and drag coefficient have little effect on pressure drop predictions, and viscous model for different turbulence models has a little larger influence on pressure drop in comparison. The most sensitive variables are related to wall shear conditions.
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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experimental study on particle steady state velocity distribution in horizontal dilute phase pneumatic conveying
Chemical Engineering Science, 2018Co-Authors: Nir Santo, Dmitry Portnikov, Itamar Eshel, Raviv Taranto, Haim KalmanAbstract:Abstract Particle and slip velocity evaluations are essential for the design of dilute phase pneumatic conveying systems in which the particles are fully suspended in the pipe, transportet at high velocities and low pressures with solid loading ratios that do not exceed 15. Although the subject was widely researched, it lacks a consistent correlation over various operating conditions and wide range of particle properties. Moreover, investigating the three dimensional velocity distribution in a cross section of a pipe may further contribute to the understanding of the phenomenon. In this study, we present a thorough experimental investigation of particle velocity obtained from 3“, 2“ and 1“ horizontal, dilute phase pneumatic conveying systems with various operating conditions and Conveyed Material with the following property ranges: 0.06 mm 940 kg m 3 ρ p 5800 kg m 3 ; 14 m s U g 28 m s ; 2.4 . · 10 4 Re g 1.4 · 10 5 ; 26 mm D 76 mm; 0.3 η 3 . The velocity was obtained using a high speed video camera combined with image processing. Data was obtained in all three dimensions for each particle allowing an investigation of the velocity distribution and the effect each component has on the equivalent velocity. The velocities of the non-axial directions were found to be considerably low in relative to the axial velocity. Therefore, in terms of the kinetic energy (e.g.), the non-axial velocities have negligible contribution; however, they have a major effect on the flow and acceleration mechanism. A correlation is presented for the axial particle velocity evaluation in the range of the tested operating conditions, which is mainly affected by the Archimedes number of the particle, with a good fit of our data and various data points from previous publications.