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Solids Flux (solid + flux)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

Direct Measurements of Instantaneous Solid Flux in a CFB Riser using a Novel Multifunctional Optical Fiber Probe

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2009
S. Ye
Abstract With a novel optical fiber probe that can measure instantaneous local particle velocity and solid concentration simultaneously, extensive experiments were conducted to study transient flow structures in a 15.1-m long circulating fluidized bed (CFB) riser of 100,mm in diameter. This study analyzed the radial and axial distributions of solid concentration, particle velocity, and their variations with nine operating conditions and at six axial levels. Instantaneous local solid concentration and particle velocity were found to be well correlated at most of the radial positions. The detailed time evolution, axial and radial distribution of instantaneous solid flux, and the variation of solid flux with operating conditions were also investigated. The radial solid flux profile showed a flat shape with a maximum at near wall area under most operating conditions. The instantaneous solid flux was found to have a strong fluctuation at a radial position of r/R,=,0.8 ~ 0.9. [source]

A critical analysis of the acceleration length and pressure profile of single-particle systems in a circulating fluidized bed

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2008
Mitali Das
Abstract A study was conducted to explore the hydrodynamic behaviors using both Geldart group A and B materials in a circulating fluidized bed unit consisting of fast column (riser) of 0.1016 m i.d. and 5.62 m height. The materials tested were 120 µm of the fluid catalytic cracking (FCC) catalyst, 166 µm of iron ore, 215 µm of coal and five types of sand particles, ranging in size from 300 to 622 µm. The superficial air velocity ranged between 2.01 and 4.681 m/s and solid fluxes of 12.5,50 kg/m2s. Riser static pressure profiles were measured for the FCC catalyst, coal, iron ore and sand particles. Acceleration lengths were determined from the data, and using these and other data from the literature two correlations for the acceleration length were established for Geldart's group A and B particles. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Experimental investigation into cavity-type inertial separators,a novel technique for development of subcompact circulating fluidized bed boilers

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2005
Animesh Dutta
Abstract Cavity-type inertial separators developed by GRI (Patent no. 2, 159, 949, Canada, 2002) were tested in a semi-industrial size circulating fluidized bed pilot plant operated at room temperature. Three rows of separators were hung from the roof of the pilot plant where one row was kept inside the riser and the others were kept in the primary separation chamber, located between the back-pass and the riser. Parameters measured were axial pressure drops along the height of the riser, vertical solids flux on the separator walls, lateral outwards solids flux in the riser with and without separator and local temperatures on the separator walls. A net downwards solids flux is on the inner wall of the separators; however, no downwards solids flux is on the outer walls of the separators. Heat transfer coefficients on the outer wall are found higher than those on the inner walls of the separator. It is also found that the presence of inertial separators not only provides additional heat transfer surfaces but also indirectly increases the heat transfer coefficients on the riser wall. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Lateral flux and velocity of FCC particles in a CFB riser

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2001
Stefan Malcus
Abstract The radial profiles of the lateral solids mass flux and the lateral solids velocity were determined for FCC particles in a 7 m tall circulating fluidtzed bed riser 0.14 m in diameter by applying a lateral flux probe and electrical capacitance tomography. The external solids mass flux was varied between 148 and 302 kg/(m2.s), while the superficial gas velocity was varied between 3.7 and 4.7 m/s. Under these conditions, a dense bottom region and an upper dilute region coexisted in the riser. Lateral fluxes in the dense bottom region reached 100 kg/(m2.s) at the wall, but fell to 14 kg/(m2.s) at the wall in the upper dilute region. At both axial locations, a net deposition of solids from the core to the annulus occurred, indicating that fully developed flow was never established under these conditions. The lateral fluxes in the bottom region were significantly larger than those found in previous studies. It was further concluded that considering the lateral solids flux to be only a function of solids concentration is an over-simplification. Les profils radiaux du flux massique de solides latéral et de la vitesse de solides iatérale ont été déterminés pour des particules de FCC dans une colonne à lit fluidisé circulant de 7 m de hauteur et de 0,14 m de diamètre, en appliquant une sonde de flux latérale et la tomographic par capacitance électrique. On a fait varier d'une part le flux massique de solides externe entre 148 et 302 kg/(m2.s) et d'autre part la vitesse de gaz superficielle entre 3,7 et 4,7 m/s. Dans ces conditions, une région inférieure dense et une région supérieure diluée coexistent dans la colonne. Les flux latéraux dans la région inférieure dense atteignent 100 kg/(m2.s) à la paroi, mais tombent à 14 kg/(m2.s) à la paroi dans la région supérieure diluée. Aux deux régions axiales, une déposition nette de solides se produit du coeur vers l'espace annulaire, indiquant que un écoulement pleinement développé n'a jamais été établi dans ces conditions. Les flux latéraux sont nettement plus important que ceux trouvés dans les études antérieures. II a en outre été conclu que le fait de considéer le flux de solides latéral uniquement comme étant fonction de la concentration de solides constituait une sur-simplification. [source]

Solids Circulation Flux and Gas Bypassing in a Pressurized Spout-fluid Bed with a Draft Tube

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2002
Rui Xiao
Abstract An experimental study on solids circulation flux and gas bypassing of a spout-fluid bed with a draft tube at elevated pressures up to 600 kPa was performed in a 200 mm diameter cylindrical steel column with a 608 conical distributor. Glass beads with mean diameter 2.067 mm were used as bed materials to investigate the effect of operating conditions and geometric configuration on the solids circulation flux and the gas distribution between the annulus and the draft tube. A novel technique has been developed to measure the solids fluxes under pressure, and gas (CO2) traces have been employed to investigate gas bypassing characteristics. The solids circulation flux is greatly enhanced when operating pressure and auxiliary gas flowrate are increased, and it is also strongly influenced by geometric configuration. Two experimental relations are proposed for predicting solids circulation flux enhancement factors. Une étude expérimentale sur le flux de circulation des solides et la dérivation du gaz d'un lit jaillissant muni d'un tube d'aspiration à des pressions élevées jusqu'à 600 kPa, a été réalisée dans une colonne d'acier cylindrique de 200 mm de diamètre avec un distributeur conique à 608. Des billes de verre d'un diamètre moyen de 2,067 mm ont été utilisées comme matériaux de lit pour étudier l'effet des conditions opératoires et de la configuration géométrique sur le flux de circulation des solides et la distribution du gaz entre l'espace annulaire et le tube d'aspiration. Une nouvelle technique a été élaborée pour mesurer les flux de solides sous pression et les caractéristiques de la dérivation du gaz ont été étudiées à l'aide de gaz traceurs (CO2). Le flux de circulation des solides est grandement amélioré lorsque la pression de fonctionnement et le débit de gaz auxiliaire sont augmentés, et il est également fortement influencé par la configuration géométrique. Deux relations expérimentales sont proposées pour la prédiction des facteurs d'amélioration du flux de circulation des solides. [source]