Showing papers in "Powder Technology in 1994"

TL;DR: In this paper, a simple first-order lumped-parameter analysis of this compression process is presented, treating the system as purely dissipative and applying the Mohr-Coulomb macroscopic failure criterion.

TL;DR: In this paper, a generalized correlation of bubble size was developed for PFBC on the basis of a comprehensive analysis of previous work, which takes into account the different flow regimes at different pressures and gas velocities, as well as the special variation of bubble sizes within the lower pressure range of the bubbling regime.

TL;DR: In this article, a computer aided (CA) particle image processing system was used to analyze images which were obtained under different superficial gas velocities and solid circulating rates at different radial positions.

TL;DR: In this paper, the development of the cross-sectional distribution of the concentration of fine powders in dilute phase pneumatic conveying through different pipe elements was examined in detail in order to characterize the degree of segregation.

TL;DR: One bed of glass ballotini and several beds of potato starch were fluidized with air at varying fluidization velocities, while the distributor plate was being vibrated at different amplitudes and frequencies to study the effect on the fluidization quality.

TL;DR: In this article, a single fiber optic reflection probe was thoroughly tested in two-phase gas for the measurement of particle velocity and concentration, and a dynamic calibration procedure for particle concentration measurements has been proposed and tested in the downflow reactor section of a pilot-scale circulating fluidized bed.

TL;DR: In this article, the breakage induced in single circular particles that impact on solid plates has been studied using a two-dimensional simulation of solid fracture, which allows the computer experimenter to vary independently material properties such as Young's modulus, Poisson's ratio and work of fracture, flexibility that is unavailable in direct experimentation.

TL;DR: The primary aim of this model is to achieve a high degree of computational efficiency, to allow simulations to be performed very rapidly on a modest sequential machine.

TL;DR: In this article, a new model is proposed to describe the effects of structural inhomogeneities in fibrous filters on pressure drop and particle collection, where the filter is subdivided into a series of elements with different structural characteristics defined by local directionally-dependent permeabilities, and the resulting three-dimensional flow field is calculated.

TL;DR: In this paper, the authors examined pickup and saltation mechanisms of solid particles from an experimental viewpoint, in relation to the prediction of the minimum conveying velocity required in horizontal pneumatic transport systems that operate in dilute-phase.

TL;DR: In this paper, 11 granular materials of various sizes and internal structures were tested in an annular attrition cell that models the breakage occurring in a failure zone of a deforming powder.

TL;DR: In this paper, a two-solvent system was used to improve micromeritic properties, such as flowability, packability and compressibility, of pharmaceutical crystals for direct tabletting.

TL;DR: In this article, a unique phosphor tracer technique was developed that measured the solids tracer concentration with time at different radial and axial positions within the cocurrent downflow circulating fluidized bed with a 140 mm inner diameter.

TL;DR: In this paper, a semi-empirical expression that relates fragmentation rate to particle size, suspension volume and ultrasonic power was derived for both eroding and non-eroding powders.

TL;DR: In this paper, a two-dimensional model granular system consisting of steel or [poly(methyl methacrylate)] discs under vibration between glass walls is analyzed by computer using Hough transform algorithms to measure the position and angle of discs within the field of view.

TL;DR: In this article, the axial voidage profiles were obtained at room temperature with two solids (sand and coal) from group B of the Geldart classification, as a function of air velocity and solids flux.

TL;DR: In this paper, a semi-empirical model was developed to predict the overall pipeline pressure drop in the horizontal slug-flow of cohesionless bulk solids in a low-velocity pneumatic conveying test rig comprising various combinations of length and diameter.

TL;DR: In this article, the size distributions of interstices in random packings of spheres whose size distributions obeyed the log-normal distribution were investigated and the structure of the interstice was modelled in terms of a network of large pores interconnected by channels and the effects of the mode of packing and the standard deviation of the spheres on this network were measured.

TL;DR: In this paper, a two-dimensional gas fluidized bed has been recorded on video and analyzed using image analysis techniques, which offer the possibility to quantify local hold-up and all kind of bubble properties, such as size, shape and velocity, as a function of the bubble height in the bed.

TL;DR: In this paper, an investigation has been carried out of the packing densities of alumina and silicon carbide powders to determine the effect of material properties, particle shape and size distribution when subjected to tapping.

TL;DR: In this article, the flow properties of wheat flour at three different moisture contents (11.8, 14.7% and 16.4%, dry basis) were measured using the Jenike shear tester with no time consolidation, over a range of loading conditions.

TL;DR: In this article, the authors used an apparatus originally designed for the experimental determination of the packing density of powders to study the segregation effects with spherical and nonspherical particles with low aspect ratios.

TL;DR: In this paper, the authors measured the wall shear stress as the sum of fluid and particle components and found that the wall stresses increase with particle diameter and density, mean flow velocity and particle concentration, and a correlation for wall stresses has been obtained in terms of the mean concentration.

TL;DR: In this paper, the physicochemical and thermal properties of various forms of magnesium stearate were examined to establish their relationship with its lubricant abilities, and the mechanism of lubrication seemed to involve water and/or gas molecules entering the spaces of the crystal lattice, causing a decrease in the interactive forces, which, in turn, leads to easier shearing of the lubricant powder particles.

TL;DR: In this paper, the authors provided a clearly defined procedure for the calculation of the liberation spectrum that can be expected when any two-phase or porphyry three-phase ore is comminuted in a ball mill or an open-circuit continuous mill.

TL;DR: In this article, a 0.026 m i.d. Lucite tube at various pressures was investigated in a vertical pneumatic transport system with glass beads (97 and 545 μm) and coal (89 and 505 μm).

TL;DR: In this paper, the hydrodynamic behavior of a cold experimental circulating fluidized bed (CFB) has been investigated using deterministic chaos theory, and the time series of experimentally measured differential pressure fluctuations along the riser height of a CFB are analyzed.

TL;DR: In this article, the attrition of fluidized cracking catalyst (FCC) powder in the jetting region of a fluidized bed indicate that the attrition rate is proportional to the orifice velocity raised to the power 3.

TL;DR: In this paper, the authors observed that the granular flow in a screw feeder is similar to plug flow and the degree of mixing was increased by either increasing the shaft diameter, decreasing the pitch, increasing the flight diameter, increasing flight thickness and angle between the upper feeder and the lower feeder, or decreasing the rotational speeds of the upper screw and lower screw.