Showing papers in "Powder Technology in 1992"

TL;DR: In this paper, Lagrangian-type numerical simulation was carried out on plug flow of cohesionless, spherical particles conveyed in a horizontal pipe and the motion of individual particles contacting each other was calculated using the equations of motion and a modified Cundall model.

TL;DR: In this paper, the angular void fraction distribution in randomly packed fixed beds of uniformly sized spheres in cylindrical containers is analyzed by a non-destructive non-linear model.

TL;DR: In this paper, a computer simulation which can randomly pack hard spheres for gravitationally stable lattices ranging from random loose packing to random close packing is described, and the model predicts that random packings form a quadrilateral in the packing density/mean coordination plane with packing densities ranging from 0.509 to 0.638 and mean coordination numbers ranging from 4.4 to 5.9.

TL;DR: In this article, the axial voidage distribution in fast fluidized beds is studied and a simple exponential function is described, with increasing voidage from the bottom to the top of the bed.

TL;DR: In this article, the hydrodynamics of cocurrent downflow gas in a 140 mm i.d. Circulating Fluidized Bed (CDCFB) was studied.

TL;DR: In this article, the slip factor of the actual gas velocity to particle velocity in the hydrodynamically fully developed region of Circulating Fluidized Bed risers (CFB) was approximated by ϕ = 1+5.6/Fr+0.47Fr0.41t=Ug/ϵVp.

TL;DR: In this paper, the influence of the dust loading and gas inlet and outlet dimensions on the performance of four industrial scale cyclones has been investigated under ambient conditions at an inlet velocity of 15 m s−1 over a loading range of 0.5 −130 g solid per m3 air.

TL;DR: The motion of alumina particles of mean size 74.9 μm in the region near to the wall of the 305 mm diameter riser of a cold model circulating fluidized bed has been studied using a high-speed video camera employing normal and magnifying lenses.

TL;DR: In this article, a unique method for imaging voidage within a fluidized bed has been developed at the Morgantown Energy Technology Center (METC), which allows high speed three-dimensional imaging of the voidage distribution in a bed to be recorded.

TL;DR: In this article, the effects of scale-up on the fluid dynamics of circulating fluidized beds (CFB) were investigated using a single cold laboratory facility with the ability to recycle fluidization gas mixtures of adjustable density and viscosity.

TL;DR: In this paper, the entrainment of Geldart Group A powders was investigated in a 7.62 cm diameter column fluidized batchwise at velocities between 0.2 and 0.7 m s −1.

TL;DR: In this paper, it was shown that the turbulent fluidization regime is a transition regime between bubbling and fast fluidization, where the gas drag force acting on them compensates with their gravity.

TL;DR: In this paper, experimental measurements of local solid mass flux were made in the riser component of two different circulating fluidized beds (CFBs) and tests were conducted in both a lab-scale riser measuring 5 cm i.d. and 2.7 m in height and a pilot scale riser of 15 cm I.d and 10.8 m height.

TL;DR: In this paper, gas and solid hydrodynamics have been studied in dilute circulating fluidized beds under conditions occurring in catalytic cracking risers, and the axial solid concentration profiles were determined in pilot and industrial scale beds.

TL;DR: In this article, a semi-empirical correlation based on the Archimedes number is presented for the prediction of the minimum gas velocity required to pick up particles in horizontal pneumatic conveying.

TL;DR: In this article, four cellulose polymers were investigated for their compaction behavior: Ethyl cellulose (EC), cellulose acetate (CA), CAB and cellulose acyclic propionate (CAPr).

TL;DR: In this article, a theory is developed to estimate the particle to particle cohesive force from pressure drop versus expansion data of packed vibrated beds of very fine particles subject to a gentle upflow of gas.

TL;DR: In this article, the effect of particle size on the adhesion behavior of two pharmaceutical powders, Starch 1500 an and Starch 1000 an, was examined using a centrifuge technique.

TL;DR: In this article, the Peclet number for radial gas mixing in the core of the upper dilute zone of a pilot scale circulating fluidized bed (CFB), 0.4 m in diameter and 9 m in height, was found to be independent of the superficial gas velocity.

TL;DR: In this article, the results of an experimental investigation of the formation of silica flocs and their subsequent breakage in a stirred tank, as a function of agitati

TL;DR: In this article, a conceptual flow regime diagram for a circulating fluidized bed riser is proposed, combining existing investigations with experimental data obtained under idealized conditions in which a fully independent control of gas velocity and solid circulation rate was conducted by use of a screw feeder for solid feed into the riser.

TL;DR: In this paper, an overview of modeling, measurement, identification and control issues arising in crystallizers is provided. Butler et al. present a model for estimating crystal size distribution from laser light scattering data and an optimal batch crystallization temperature profile is computed.

TL;DR: In this article, a three-dimensional hydrodynamic kinetic theory granular flow model was developed and used to compute bubble and solids motion in a rectangular fluid flow model, which was then used for the calculation of bubble motion.

TL;DR: In this article, the local slip velocity between gas and solid in the riser of a dilute circulating fluidized bed was investigated through simultaneous measurements of the gas and the solid at different velocities.

TL;DR: This paper showed that the smallest particles are not the most easily elutriated from fluidized beds of mixed size particles, and that electrostatic forces were not responsible for particle agglomeration.

TL;DR: In this article, a light transmission technique has been developed for measurement of the local porosity in two-dimensional gas-fluidized beds and the principles of liquid-solid fluidization and vibrofluidization were employed to perform the necessary calibration.

TL;DR: In this article, the authors provide modifications to several conclusive model equations presented by Gibilaro and Foscolo by considering the correct buoyancy force expression which is based on the density of fluid alone.

TL;DR: In this paper, the authors reported some tests of dust explosibility made in vessels of two different sizes, i.e., 1 m 3 and 20 l, and made some remarks on the validity of the cubic law in the 20 l sphere.

TL;DR: In this article, the transition state from mass flow to funnel or plug flow in hoppers is defined as functions of the hopper angle, granular material friction angle, and dry friction angle at the walls.