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Coarse Particles (coarse + particle)
Selected AbstractsEntrainment Rate of Coarse Particles at Different Temperatures in Gas Fluidized BedsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2007Jeong-Hoo Choi Abstract Based on available experimental data, an empirical relationship is developed for the entrainment rate of coarse particles at the exit of gas-fluidized beds, including the effects of fine particles in the bed, temperature, gas velocity, particle size and density, and column size. It predicts well the influence of fine particles on the entrainment rate of coarse particles, taking into account the momentum of the fine particles and the effect of superficial gas velocity. It also accounts well for the influence of temperature at different solid densities and gas velocities. À partir de données expérimentales disponibles, on a mis au point une relation empirique pour la vitesse d'entraînement des grosses particules à la sortie des lits fluidisés de gaz, incluant les effets des particules fines dans le lit, la température, la vitesse de gaz, la taille et la masse volumique des particules ainsi que la dimension de la colonne. Cette relation prédit bien l'influence des particules fines sur la vitesse d'entraînement des grosses particules, en tenant compte de la quantité de mouvement des particules fines et de l'effet de la vitesse de gaz superficielle. Elle prend bien en compte également l'influence de la température à différentes masses volumiques de solides et vitesses de gaz. [source] Cytochemical and ultrastructural characterization of growing colonies of human embryonic stem cellsJOURNAL OF ANATOMY, Issue 4 2004Kohei Johkura Abstract The morphology of human embryonic stem (ES) cells changes with their colonial growth. For a better understanding of the growth of ES cell colonies in culture, we determined their cytochemical and ultrastructural characteristics focusing on images of living cells under a phase contrast microscope. During the initial growth stages, the colonies exhibited a mosaic appearance with discernible cell,cell borders. PAS staining coupled with amylase digestion demonstrated that the bright granules and dark deposits in the cytoplasm contained glycogen. Ultrastructurally they were glycogen accumulations, and clustered open spaces associated with various amounts of glycogen. Although intercellularly heterogeneous, these structures were detectable throughout colony growth. As the colonies grew, compaction towards the centre emerged and increased, accompanied by heterogeneous increases in coarse particles with or without a halo. TUNEL showed these particles to consist at least in part of apoptotic cells/bodies. Transmission electron microscopy indicated that most apoptotic cells had been phagocytosed by intact ES cells. Spontaneous differentiation was detected occasionally in the periphery of the colonies. The presence of PAS-positive fibrous structures not susceptible to amylase digestion and laminin-immunoreactivity indicated the accumulation of extracellular matrix in the peripheral differentiated areas. These findings made it possible to determine the growth stage of human ES cell colonies. [source] Role of bed height and amount of dust on the efficiency of sound-assisted fluidized bed filter/afterburnerAICHE JOURNAL, Issue 12 2009Riccardo Chirone Abstract A 40-mm sound-assisted fluidized bed filter/afterburner for hot gas clean-up has been characterized in terms of bed saturation time, total amount of collected particles, fraction of fine particles permanently adhered on the coarse bed particles, and efficiency of using a regeneration strategy based on mechanical (attrition) and/or chemical (combustion) action. Experiments have been carried out at ambient temperature as well as at 850°C, with and without application of sound and varying bed height and amount of dust in the gas flow. The controversial effect of the application of sound: not only enhancement of particles interactions but also increase of fines permanently adhering on bed coarse particles is presented and discussed. A simplified model has been developed to obtain rough predictions of bed height which maximize fine particles capture, bed saturation time, total amount of particles collected in the bed, fraction of fine particles loading present as adhered particles on bed particles. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] The influence of the particle size distribution on fluidized bed hydrodynamics using high-throughput experimentationAICHE JOURNAL, Issue 8 2009Renske Beetstra Abstract The goal of the described project is to design mixtures of particles with optimal fluidization properties. Using high-throughput experimentation, a novel approach to study hydrodynamics in fluidized beds, the relevant properties can be obtained in a limited period of time. This approach is demonstrated by assessing the influence of particle size distribution on fluidized bed hydrodynamics of Geldart A powders. By manipulating the width of the particle size distribution of alumina powder, the bubble diameter is reduced up to 40%. The addition of fines to a given particle size distribution also decreases the bubble diameter up to 40%, whereas the addition of coarse particles hardly influences the bubble size. At low gas velocities, the bubble size was found to increase with fines addition or increasing standard deviation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] A Sampling Approach for Evaluating Particle Loss During Continuous Field Measurement of Particulate MatterPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 2 2005Christopher A. Noble Abstract A method for evaluating sample bias in field measurements is presented. Experiments were performed in the field and laboratory to quantify the bias as a function of particle size for the scanning mobility particle sizer and the aerodynamic particle sizer. Sources of bias and sample loss considered in this work were sampling line loss, instrumental differences and inlet efficiencies. Measurement of the bias and sample loss allow for correction of the data acquired in the field, so as to obtain more representative samples of atmospheric concentrations. Substantial losses of fine and ultrafine particle count were observed, with sampling line losses ranging from 10,50,%, dependent on particle size. Only minor line losses were observed for coarse particles (approximately 5,%) because the sampling line was oriented vertically. Please note: corrected DOI, in print wrong DOI (10.1002/ppsc.200400939) [source] Entrainment Rate of Coarse Particles at Different Temperatures in Gas Fluidized BedsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2007Jeong-Hoo Choi Abstract Based on available experimental data, an empirical relationship is developed for the entrainment rate of coarse particles at the exit of gas-fluidized beds, including the effects of fine particles in the bed, temperature, gas velocity, particle size and density, and column size. It predicts well the influence of fine particles on the entrainment rate of coarse particles, taking into account the momentum of the fine particles and the effect of superficial gas velocity. It also accounts well for the influence of temperature at different solid densities and gas velocities. À partir de données expérimentales disponibles, on a mis au point une relation empirique pour la vitesse d'entraînement des grosses particules à la sortie des lits fluidisés de gaz, incluant les effets des particules fines dans le lit, la température, la vitesse de gaz, la taille et la masse volumique des particules ainsi que la dimension de la colonne. Cette relation prédit bien l'influence des particules fines sur la vitesse d'entraînement des grosses particules, en tenant compte de la quantité de mouvement des particules fines et de l'effet de la vitesse de gaz superficielle. Elle prend bien en compte également l'influence de la température à différentes masses volumiques de solides et vitesses de gaz. [source] Classification of Suspensions by Means of Rotating Filter Discs and Autodynamic High-Frequency BackwashingCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2010L. Steinke Abstract A new method for the classification of suspensions by means of rotating filter discs is presented. The classification without a filter cake buildup by means of a single shaft disc filter is possible using the high-frequency autodynamic backwashing method. High-frequency autodynamic backwashing results from an overpressure fluctuation between the filtrate and concentrate sides, resulting in different flow directions of the filtrate volume flow. The main parameters are the centrifugal force acting on the fluid inside the discs in combination with the fact that the discs are slightly inclined. It is demonstrated that the separation of coarse particles is entirely possible. [source] Investigation of Fluid and Coarse-Particle Dynamics in a Two-Dimensional Spouted BedCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2004T. Swasdisevi Abstract The aerodynamics of particles and gas flow in a two-dimensional spouted bed (2DSB) with draft plates is investigated with the aid of the discrete element method. The geometry of the 2DSB with draft plates is set as close as possible to the experimental apparatus of Kudra [1] and Kalwar [2]. The physical properties of the coarse particles are similar to those of shelled corn. The calculated minimum spouting velocity and pressure drop agree well with the correlations of Kudra [1] and Kalwar [2]. In the spout region, the particle vertical velocities are found to decrease as the height increases. The fluid velocity in the downcomer region decreases as the superficial gas velocity increases. The particle circulation rate increases when the friction coefficient decreases or the separation height increases. At the minimum spouting velocity, the bed height does not affect the particle circulation rate in the 2DSB with draft plates. The draft plates not only reduce the minimum spouting velocity and pressure drop but also increase the maximum spoutable bed height. The effect of taking out the draft plates on the spouting phenomenon is investigated and the effect of putting in a deflector on the possible breakage of the particles is also estimated. [source] | ||||||||||