Hydrodynamic characteristics of fluidization in a conical or tapered bed differ from those in a columnar bed because the superficial velocity in the bed varies in the axial direction. Fixed and fluidized regions could...Hydrodynamic characteristics of fluidization in a conical or tapered bed differ from those in a columnar bed because the superficial velocity in the bed varies in the axial direction. Fixed and fluidized regions could coexist and sharp variations in pressure drop could occur, thereby giving rise to a noticeable pressure drop-flow rate hysteresis loop under incipient fluidization conditions. To explore these unique properties, several experiments were carried out using homogeneous, well-mixed, ternary mixtures with three dif- ferent particle sizes at varying composition in gas-solid conical fluidized beds with varying cone angles. The hydrodynamic characteristics determined include the minimum fluidization velocity, bed fluctuation, and bed expansion ratios. The dependence of these quantities on average particle diameter, mass fraction of the fines in the mixture, initial static bed height, and cone angle is discussed. Based on dimensional analysis and factorial design, correlations are developed using the system parameters, i.e. geometry of the bed （cone angle）, particle diameter, initial static bed height, density of the solid, and superficial velocity of the fluidizing medium. Experimental values of minimum fluidization velocity, bed fluctuation, and bed expansion ratios were found to agree well with the developed correlations.展开更多
Hydrodynamics of conical fluidized bed differ from that of columnar beds by the fact that a velocity gradient exists along the axial direction of the bed.The gas–liquid–solid fluidized bed has emerged in recent year...Hydrodynamics of conical fluidized bed differ from that of columnar beds by the fact that a velocity gradient exists along the axial direction of the bed.The gas–liquid–solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operations.Such a device is of considerable industrial importance as evident from its wide applications in chemical,refining,petrochemical,biochemical processing,pharmaceutical and food industries.To explore this,a series of experiments have been carried out for homogeneous well-mixed ternary mixtures of dolomite of varying compositions in a three-phase conical fluidized bed.The hydrodynamic characteristics determined included the bed pressure drop,bed fluctuation and bed expansion ratios.The single and combined effects of operating parameters such as superficial gas velocity,superficial liquid velocity,initial static bed height,average particle size and cone angle on the responses have been analyzed using response surface methodology(RSM).A 25 full factorial central composite experimental design has been employed.Analysis of variance(ANOVA) showed a high coefficient of determination value and satisfactory prediction second-order regression models have been derived.Experimental values of bed pressure drop,bed fluctuation and bed expansion ratios have been found to agree well with the developed correlations.展开更多
文摘Hydrodynamic characteristics of fluidization in a conical or tapered bed differ from those in a columnar bed because the superficial velocity in the bed varies in the axial direction. Fixed and fluidized regions could coexist and sharp variations in pressure drop could occur, thereby giving rise to a noticeable pressure drop-flow rate hysteresis loop under incipient fluidization conditions. To explore these unique properties, several experiments were carried out using homogeneous, well-mixed, ternary mixtures with three dif- ferent particle sizes at varying composition in gas-solid conical fluidized beds with varying cone angles. The hydrodynamic characteristics determined include the minimum fluidization velocity, bed fluctuation, and bed expansion ratios. The dependence of these quantities on average particle diameter, mass fraction of the fines in the mixture, initial static bed height, and cone angle is discussed. Based on dimensional analysis and factorial design, correlations are developed using the system parameters, i.e. geometry of the bed （cone angle）, particle diameter, initial static bed height, density of the solid, and superficial velocity of the fluidizing medium. Experimental values of minimum fluidization velocity, bed fluctuation, and bed expansion ratios were found to agree well with the developed correlations.
文摘Hydrodynamics of conical fluidized bed differ from that of columnar beds by the fact that a velocity gradient exists along the axial direction of the bed.The gas–liquid–solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operations.Such a device is of considerable industrial importance as evident from its wide applications in chemical,refining,petrochemical,biochemical processing,pharmaceutical and food industries.To explore this,a series of experiments have been carried out for homogeneous well-mixed ternary mixtures of dolomite of varying compositions in a three-phase conical fluidized bed.The hydrodynamic characteristics determined included the bed pressure drop,bed fluctuation and bed expansion ratios.The single and combined effects of operating parameters such as superficial gas velocity,superficial liquid velocity,initial static bed height,average particle size and cone angle on the responses have been analyzed using response surface methodology(RSM).A 25 full factorial central composite experimental design has been employed.Analysis of variance(ANOVA) showed a high coefficient of determination value and satisfactory prediction second-order regression models have been derived.Experimental values of bed pressure drop,bed fluctuation and bed expansion ratios have been found to agree well with the developed correlations.
