The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform
Mark Jones - One of the best experts on this subject based on the ideXlab platform.
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Stress field measurements in slug flow pneumatic Conveying
2012Co-Authors: Peter W Wypych, David B Hastie, T. Krull, Mark Jones, Alan W. RobertsAbstract:Dense-phase is a specific form of pneumatic Conveying, in which bulk solids are transported along a pipeLine at relatively low Conveying speeds. Slug-flow pneumatic Conveying is a full-bore mode of flow within the dense-phase flow regime where granular materials are transported as plugs at Conveying speeds generally below 5 m/s. Especially applications in the food and processing industry require Conveying of fragile and brittle materials which makes this form of pneumatic Conveying well suited due to its more gentle handling characteristics. An accurate assessment of the stress field and the wall friction is the crucial step to a reliable prediction of the Conveying parameters, mainly the pressure drop for any given combination of air and material mass flow rate. With the help of a newly developed test apparatus, two important parameters can now be determined for a moving material slug; the wall friction coefficient and the stress transmission coefficient, which relates the slug’s lateral to axial stress. This paper reports on the experiments conducted with the stress transmission test cell while it was inserted into a full scale pneumatic Conveying Line.
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Characterization of the gas pulse frequency, amplitude and velocity in non-steady dense phase pneumatic Conveying of powders
Particuology, 2008Co-Authors: Kenneth Williams, Mark Jones, A. A. CennaAbstract:Abstract Current modelling techniques for the prediction of Conveying Line pressure drop in low velocity dense phase pneumatic Conveying are largely based on steady state analyses. Work in this area has been on-going for many years with only marginal improvements in the accuracy of prediction being achieved. Experimental and theoretical investigations undertaken by the authors suggest that the flow mechanisms involved in dense phase Conveying are dominated by transient effects rather than those of steady state and are possibly the principal reasons for the limited improvement in accuracy. This paper reports on investigations on the pressure fluctuation behaviour in dense phase pneumatic Conveying of powders. The pressure behaviour of the gas flow in the top section of the pipeLine was found to exhibit pulsatile oscillations. In particular, the pulse velocity showed variation in magnitude while the frequency of the oscillations rarely exceeded 5 Hz. A wavelet analysis using the Daubechie 4 wavelet found that the amplitude of the oscillations increased along the pipeLine. Furthermore, there was significant variation in gas pulse amplitude for different types of particulate material.
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Stress-Field Modeling and Pressure Drop Prediction for Slug-Flow Pneumatic Conveying in an Aerated Radial Stress Chamber
Particulate Science and Technology, 2004Co-Authors: T. Krull, Mark Jones, S. KeysAbstract:Slug-flow pneumatic Conveying is a full-bore mode of flow within the dense-phase flow regime where bulk materials are transported in the form of slugs at Conveying speeds below saltation velocity. The mechanism of slug-flow pneumatic Conveying consists of the particles being picked up from the stationary bed in front of a moving slug while the same amount of material is deposited behind the slug. Stress field modeling of the material slug is the first step in developing a prediction model for the pressure drop along a pneumatic Conveying Line. However, a reliable prediction strongly relies on an accurate assessment of several factors, including the particle properties, pipeLine dimensions, and operating conditions. So far, the particle diameter has always been one of the crucial parameters, which is not desirable in regards to the limitations it imposes on the choice of bulk materials. This article focuses on one parameter, the stress transmission coefficient kw, which relates the lateral wall stress within a slug of material to the axial stress. To date, this parameter could not be measured directly in an aerated material bed and had to be estimated. Inaccuracies within the prediction were therefore unavoidable. A newly designed test chamber now enables the measurement of the lateral and axial stresses within a slug, which leads directly to this stress transmission coefficient. This article outLines the design of the test apparatus and reports on the experimental results. For the two materials tested, an exponential correlation between the pressure on top of the slug (frontal stress) and the stress transmission coefficient was obtained. Calculating the wall friction coefficient leads to a constant value above a certain material-specific air velocity
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Measurement of the stress transmission coefficient of material slugs in an aerated radial stress chamber
Particulate Science and Technology, 2003Co-Authors: T. Krull, Mark Jones, Alan W. Roberts, Peter W WypychAbstract:In dense-phase pneumatic Conveying, particles are transported along a pipeLine at relatively low Conveying speeds. Due to the relatively gentle handling characteristics of this mode of flow, it is suitable for Conveying fragile and brittle bulk materials used in the food and chemical industries. The simulation of the stress field within a slug aims at developing an accurate prediction model for the pressure drop along a pneumatic Conveying Line. A reliable prediction of the pressure drop strongly depends on an accurate assessment of the particle properties, the pipeLine dimensions, and the operating conditions. In past decades, a few models have been developed to serve this purpose, most of them including the mean particle diameter as a crucial parameter. This generally limits the selection of materials to those of nearly spherical particle shape, as it is extremely difficult to obtain a representative diameter for irregularly shaped particles or bulk commodities comprising differently sized and/or shaped...
Andrew Sowinski - One of the best experts on this subject based on the ideXlab platform.
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Electrostatic charging behaviour of polypropylene particles during pulse pneumatic Conveying with spiral gas flow pattern
Chemical Engineering Science, 2021Co-Authors: Milad Taghavivand, Poupak Mehrani, Andrew Sowinski, Kwangseok ChoiAbstract:Abstract The electrostatic charging behaviour of 5-µm and 1500-µm polypropylene particles were studied during pulse pneumatic Conveying with a spiral air flow. The Conveying Line was made of stainless steel with a total length of 1.3 m and inner diameter of 0.035 m. Effects of Conveying gas velocity as well as particles mass loading were studied on particles charge-to-mass (Q/m) ratio. A high-speed camera set at 5000 frames per second (fps) capturing speed was used to record the particles movement pattern within the Conveying Line. Results clearly indicated a relationship between the particles motion pattern and their electrostatic charging behaviour. A direct relationship was observed between the Conveying gas velocity and particles Q/m, whereas in general, particles Q/m magnitude was found to be inversely related with the mass loading. The Q/m of larger particles was found to be greater than that for the smaller particles. Additionally, charge measurements were performed and compared between a cyclone-type Faraday cage and a through-type Faraday cage with a filter bag inside. It was observed that the charge measured by these Faraday cages could differ drastically depending on particles size. The back pressure created inside the filter bag was suspected to be a significant contributor for such as observation.
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Electrostatic charging behaviour of a silica powder during pulse pneumatic Conveying
Powder Technology, 2020Co-Authors: Milad Taghavivand, Benjamin J. Cho, Poupak Mehrani, Andrew SowinskiAbstract:Abstract The electrostatic charging of a dehydrated and non-dehydrated silica powder used as a catalyst support in polyethylene production was investigated using pulse pneumatic injection. The charge-to-mass ratios (Q/m) of powders were studied at varying Conveying Line lengths and pathways, Conveying gas velocities and powder mass loadings. Results showed a direct relationship between the Conveying Line length and the powders' charging, whereas changing the pathway did not show a significant effect. Increasing the mass loading from 0.1 to 1 g decreased the powders' Q/m, while increasing the mass loading from 1 to 2 g showed no influence. Increasing the Conveying gas velocity from 15 to 30 m/s increased the Q/m of the non-dehydrated powder, whereas no change was observed in the case of the dehydrated powder. Significant tube fouling was observed with the dehydrated powder, while the non-dehydrated powder left a negligible amount of fouling.
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Study of electrostatic charging of single particles during pneumatic Conveying
Powder Technology, 2019Co-Authors: Milad Taghavivand, Andrew Sowinski, Bilal Elchamaa, Poupak MehraniAbstract:Abstract In this study the electrostatic charging behaviour of single particles of different sizes and materials were investigated during pneumatic Conveying. The particles used included 3.18 and 0.79 mm PTFE as well as 3.18 mm Nylon particles. Particles were pneumatically conveyed in stainless steel (316 Grade) tubes with 4.57 mm inner diameter. Effects of Conveying tube length, Conveying gas velocity and pathway of particles (i.e. addition of 90° elbows and smooth bends) on particles charge-to-mass ratio were studied. Results showed that the smaller PTFE particles reached the saturation charge in the longest straight tube at all Conveying gas velocities tested. Whereas the other two larger particles reached saturation charge only in the longest straight tube and at the lowest gas velocity. For large particles moving in straight tubes, in general, the lowest gas velocity resulted in a higher charge-to-mass ratio. The particles pathway had a large impact on their charging behaviour at high gas velocities, whereas at the lowest gas velocity, the total tube length was more influential on particles charging. Finally, the charge of the particles determined by measuring the current from the Conveying Line was found to be in good agreement with that measured directly by a Faraday cage.
Milad Taghavivand - One of the best experts on this subject based on the ideXlab platform.
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Electrostatic charging behaviour of polypropylene particles during pulse pneumatic Conveying with spiral gas flow pattern
Chemical Engineering Science, 2021Co-Authors: Milad Taghavivand, Poupak Mehrani, Andrew Sowinski, Kwangseok ChoiAbstract:Abstract The electrostatic charging behaviour of 5-µm and 1500-µm polypropylene particles were studied during pulse pneumatic Conveying with a spiral air flow. The Conveying Line was made of stainless steel with a total length of 1.3 m and inner diameter of 0.035 m. Effects of Conveying gas velocity as well as particles mass loading were studied on particles charge-to-mass (Q/m) ratio. A high-speed camera set at 5000 frames per second (fps) capturing speed was used to record the particles movement pattern within the Conveying Line. Results clearly indicated a relationship between the particles motion pattern and their electrostatic charging behaviour. A direct relationship was observed between the Conveying gas velocity and particles Q/m, whereas in general, particles Q/m magnitude was found to be inversely related with the mass loading. The Q/m of larger particles was found to be greater than that for the smaller particles. Additionally, charge measurements were performed and compared between a cyclone-type Faraday cage and a through-type Faraday cage with a filter bag inside. It was observed that the charge measured by these Faraday cages could differ drastically depending on particles size. The back pressure created inside the filter bag was suspected to be a significant contributor for such as observation.
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Electrostatic charging behaviour of a silica powder during pulse pneumatic Conveying
Powder Technology, 2020Co-Authors: Milad Taghavivand, Benjamin J. Cho, Poupak Mehrani, Andrew SowinskiAbstract:Abstract The electrostatic charging of a dehydrated and non-dehydrated silica powder used as a catalyst support in polyethylene production was investigated using pulse pneumatic injection. The charge-to-mass ratios (Q/m) of powders were studied at varying Conveying Line lengths and pathways, Conveying gas velocities and powder mass loadings. Results showed a direct relationship between the Conveying Line length and the powders' charging, whereas changing the pathway did not show a significant effect. Increasing the mass loading from 0.1 to 1 g decreased the powders' Q/m, while increasing the mass loading from 1 to 2 g showed no influence. Increasing the Conveying gas velocity from 15 to 30 m/s increased the Q/m of the non-dehydrated powder, whereas no change was observed in the case of the dehydrated powder. Significant tube fouling was observed with the dehydrated powder, while the non-dehydrated powder left a negligible amount of fouling.
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Study of electrostatic charging of single particles during pneumatic Conveying
Powder Technology, 2019Co-Authors: Milad Taghavivand, Andrew Sowinski, Bilal Elchamaa, Poupak MehraniAbstract:Abstract In this study the electrostatic charging behaviour of single particles of different sizes and materials were investigated during pneumatic Conveying. The particles used included 3.18 and 0.79 mm PTFE as well as 3.18 mm Nylon particles. Particles were pneumatically conveyed in stainless steel (316 Grade) tubes with 4.57 mm inner diameter. Effects of Conveying tube length, Conveying gas velocity and pathway of particles (i.e. addition of 90° elbows and smooth bends) on particles charge-to-mass ratio were studied. Results showed that the smaller PTFE particles reached the saturation charge in the longest straight tube at all Conveying gas velocities tested. Whereas the other two larger particles reached saturation charge only in the longest straight tube and at the lowest gas velocity. For large particles moving in straight tubes, in general, the lowest gas velocity resulted in a higher charge-to-mass ratio. The particles pathway had a large impact on their charging behaviour at high gas velocities, whereas at the lowest gas velocity, the total tube length was more influential on particles charging. Finally, the charge of the particles determined by measuring the current from the Conveying Line was found to be in good agreement with that measured directly by a Faraday cage.
Chi-hwa Wang - One of the best experts on this subject based on the ideXlab platform.
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Effects of an electrostatic field in pneumatic Conveying of granular materials through incLined and vertical pipes
Chemical Engineering Science, 2006Co-Authors: Eldin Wee Chuan Lim, Yan Zhang, Chi-hwa WangAbstract:Abstract The pneumatic transport of granular materials through an incLined and vertical pipe in the presence of an electrostatic field was studied numerically using the discrete element method (DEM) coupled with computational fluid dynamics (CFD) and a simple electrostatic field model. The simulation outputs corresponded well with previously reported experimental observations and measurements carried out using electrical capacitance tomography and high-speed camera techniques in the present study. The eroding dunes and annular flow regimes, observed experimentally by previous research workers in incLined and vertical pneumatic Conveying, respectively, were reproduced computationally by incorporating a simplified electrostatic field model into the CFD–DEM method. The flow behaviours of solid particles in these regimes obtained from the simulations were validated quantitatively by experimental observations and measurements. In the presence of a mild electrostatic field, reversed flow of particles was seen in a dense region close to the bottom wall of the incLined Conveying pipe and forward flow in a more dilute region in the space above. At sufficiently high field strengths, complete backflow of solids in the incLined pipe may be observed and a higher inlet gas velocity would be required to sustain a net positive flow along the pipe. However, this may be at the expense of a larger pressure drop over the entire Conveying Line. In addition, the time required for a steady state to be attained whereby the solids flow rate remains substantially constant with respect to time was also dependent on the amount of electrostatic effects present within the system. The transient period was observed to be longer when the electrostatic field strength was higher. Finally, a flow map or phase diagram was proposed in the present study as a useful reference for designers of incLined pneumatic Conveying systems and a means for a better understanding of such systems.
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Pneumatic Conveying of granular solids in horizontal and incLined pipes
AIChE Journal, 2004Co-Authors: Kewu Zhu, Chun Kit Wong, S. Madhusudana Rao, Chi-hwa WangAbstract:Computational fluid dynamics simulations are used to investigate the pneumatic Conveying of granular solids through an incLined pipe at different inclinations. Model predictions agreed reasonably well with the measurements reported by Tsuji and Morikawa in 1982 for mean gas and solids velocities. The results of influence of model parameters, inclination angle, and feeding conditions on the flow patterns were also reported. Particle–wall collisions were found to have a very significant effect on the solids distribution over the cross section of the Conveying tube for large particles. Upon introducing finite-amplitude sinusoidal fluctuations in the gas velocity at the inlet of the pipe, solids density waves were observed to move along the Conveying Line with significant axial dispersions. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1729–1745, 2004
Poupak Mehrani - One of the best experts on this subject based on the ideXlab platform.
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Electrostatic charging behaviour of polypropylene particles during pulse pneumatic Conveying with spiral gas flow pattern
Chemical Engineering Science, 2021Co-Authors: Milad Taghavivand, Poupak Mehrani, Andrew Sowinski, Kwangseok ChoiAbstract:Abstract The electrostatic charging behaviour of 5-µm and 1500-µm polypropylene particles were studied during pulse pneumatic Conveying with a spiral air flow. The Conveying Line was made of stainless steel with a total length of 1.3 m and inner diameter of 0.035 m. Effects of Conveying gas velocity as well as particles mass loading were studied on particles charge-to-mass (Q/m) ratio. A high-speed camera set at 5000 frames per second (fps) capturing speed was used to record the particles movement pattern within the Conveying Line. Results clearly indicated a relationship between the particles motion pattern and their electrostatic charging behaviour. A direct relationship was observed between the Conveying gas velocity and particles Q/m, whereas in general, particles Q/m magnitude was found to be inversely related with the mass loading. The Q/m of larger particles was found to be greater than that for the smaller particles. Additionally, charge measurements were performed and compared between a cyclone-type Faraday cage and a through-type Faraday cage with a filter bag inside. It was observed that the charge measured by these Faraday cages could differ drastically depending on particles size. The back pressure created inside the filter bag was suspected to be a significant contributor for such as observation.
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Electrostatic charging behaviour of a silica powder during pulse pneumatic Conveying
Powder Technology, 2020Co-Authors: Milad Taghavivand, Benjamin J. Cho, Poupak Mehrani, Andrew SowinskiAbstract:Abstract The electrostatic charging of a dehydrated and non-dehydrated silica powder used as a catalyst support in polyethylene production was investigated using pulse pneumatic injection. The charge-to-mass ratios (Q/m) of powders were studied at varying Conveying Line lengths and pathways, Conveying gas velocities and powder mass loadings. Results showed a direct relationship between the Conveying Line length and the powders' charging, whereas changing the pathway did not show a significant effect. Increasing the mass loading from 0.1 to 1 g decreased the powders' Q/m, while increasing the mass loading from 1 to 2 g showed no influence. Increasing the Conveying gas velocity from 15 to 30 m/s increased the Q/m of the non-dehydrated powder, whereas no change was observed in the case of the dehydrated powder. Significant tube fouling was observed with the dehydrated powder, while the non-dehydrated powder left a negligible amount of fouling.
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Study of electrostatic charging of single particles during pneumatic Conveying
Powder Technology, 2019Co-Authors: Milad Taghavivand, Andrew Sowinski, Bilal Elchamaa, Poupak MehraniAbstract:Abstract In this study the electrostatic charging behaviour of single particles of different sizes and materials were investigated during pneumatic Conveying. The particles used included 3.18 and 0.79 mm PTFE as well as 3.18 mm Nylon particles. Particles were pneumatically conveyed in stainless steel (316 Grade) tubes with 4.57 mm inner diameter. Effects of Conveying tube length, Conveying gas velocity and pathway of particles (i.e. addition of 90° elbows and smooth bends) on particles charge-to-mass ratio were studied. Results showed that the smaller PTFE particles reached the saturation charge in the longest straight tube at all Conveying gas velocities tested. Whereas the other two larger particles reached saturation charge only in the longest straight tube and at the lowest gas velocity. For large particles moving in straight tubes, in general, the lowest gas velocity resulted in a higher charge-to-mass ratio. The particles pathway had a large impact on their charging behaviour at high gas velocities, whereas at the lowest gas velocity, the total tube length was more influential on particles charging. Finally, the charge of the particles determined by measuring the current from the Conveying Line was found to be in good agreement with that measured directly by a Faraday cage.