Showing papers in "Powder Technology in 1979"

TL;DR: In this article, the authors present data obtained with several solids in cold model rigs, which serve to delineate the fluidization regimes noted above and their boundaries, and also throw light on the phenomenon of choking.

TL;DR: In this paper, a purely kinematic model involving only one experimental constant is proposed for the description of the velocity field in a granular material discharging from a hopper, and experimental measurements have been made on velocity distributions on a two-dimensional hopper and excellent agreement with the model is found.

TL;DR: In this paper, the total bed pressure drop, the pressure-drop profile, bed expansion and bed voidage have been measured for a variety of binary particle mixtures over a wide range of gas velocities.

TL;DR: In this article, a simple expression for estimating the void fraction in mixtures of two or more monodisperse components of different sizes is proposed, which is compared to experimental data and it is shown that the predicted and observed void fractions are in satisfactory agreement.

TL;DR: In this article, a simplified graphical construction is developed for a binary particle mixture similar to that of Kynch, which was for a single species, for the slip velocity of each particle species within a polydisperse particle mixture moving vertically through a liquid.

TL;DR: In this paper, the effect of shape on hindered settling in creeping flow was investigated using spherical glass beads, cubical sodium chloride crystals and ABS plastic pellets, brick-like sugar crystals, and angular (imperfect octahedral) mineral silicate crystals.

TL;DR: Ordered powder mixtures have been produced using comparatively fine powder systems, such as a ball mill and a cube mixer as discussed by the authors, which have a higher degree of homogeneity than those hitherto prepared.

TL;DR: In this paper, a steric field-flow fractionation and segregation of particles according to particle size is proposed, where gravity is used as the force field and the desired particle movement is obtained by rotating the flow channel about an axis substantially parallel to the direction of flow to an inclined position with respect to a force field.

TL;DR: In this paper, pressure drop and choking were calculated for dense-phase vertical pneumatic conveying of solids using a model employing two continuity and two momentum equations, and the calculated pressure drops and choking velocities were found to be in good agreement with IGT high-pressure lift-line experiments.

TL;DR: In this paper, the authors reviewed the literature on gas distributors for gas fluidized beds from the point of view of stable operation of the bed and suggested an equation relating the minimum value of the ratio of the distributor pressure drop for stable operation and the bed pressure drop to the aspect ratio.

TL;DR: In this article, a dimensionless empirical constant, k, is proposed to replace the kinematic constant, B, for the flow of coarse granular media in the absence of air drag.

TL;DR: In this paper, the porosities in ternary mixtures of spheres and of coke particles were compared with the data existing in the literature and it was found that the porosity in the systems examined show similar behaviour which is dictated by the porosi of the pseudo-binaries of the two extreme size particles in the mixture.

TL;DR: In this paper, the effect of bed moisture on fluidization characteristics of fine powders has been studied and the results indicate that the sensitivity to moisture drastically changes from porous to non-porous materials.

TL;DR: In this paper, the characteristics of such distributors as are commonly employed in laboratories, pilot plant and large scale operations have been investigated in a 30.5 cm by 30. 5 cm square fluidized bed as a function of air fluidizing velocity and bed height.

TL;DR: In this article, nine shape indices have been defined using three kinds of powder particles which include circularity and elongation as reltionships between characteristic diameters, have been examined on their numerical lines.

TL;DR: In this paper, the subsidence theory is compared with the steady-state flux theory, which is a generalization of the steady state flux theory developed by Litwiniszyn and independently developed much later by the author.

TL;DR: In this paper, the authors analyzed the flow in both packed and fluidized beds in a rotating system and found that the tangential velocity distribution in the bed under these conditions is directly proportional to the bed radius.

TL;DR: In this paper, a study of the effect of sodium salicylate concentrations on ordered mixing homogeneity was carried out on a direct compression vehicle with both ordered and random mechanisms of mixing.

TL;DR: In this paper, four approaches to assess the homogeneity of a multicomponent solids mixture have been proposed and the mixing indices proposed are estimated on the basis of the 1. pseudo-binary mixture concept 2. pooled variance of the whole system 3. determinant of the sample covariance matrix or 4. absolute deviations from the population means.

TL;DR: While it is found that much of the published data is reliable, doubt is cast on some of the data presented in the most extensive laboratory investigation undertaken, recommendation for experimental procedures and procedures for the determination of bin pressures are presented.

TL;DR: In this article, a new method using parametric Fourier descriptors to represent particle shape is discussed, which is compared with the (R, θ) method described elsewhere.

TL;DR: In this article, the expected trend of an increasing homogeneity (decreasing standard deviation) as the degree of ordering of a component in the mixture increases was investigated, and two different systems were considered, a binary powder mixture where one component is partially ordered and a tertiary powder mixture, where the third component is totally ordered, but disproportionately distributed between the other two components.

TL;DR: In this paper, the authors made measurements of flow rates and tensile strengths of a variety of powders over a range of temperatures from −20° to 200°C and explained the effects of temperature on the hardness and elasticities of the materials concerned, and the distances between the particles.

TL;DR: In this paper, the flow properties of fluidized solids through a horizontal open channel with a porous tile distributor are reported, where the shear stress at the vertical wall of the experimental section was measured directly and that across the distributor estimated from the difference between the total stress represented by the pressure drop along the experimental sections and the wall shear stresses.

TL;DR: In this paper, the mixing of a cohesive drug with a cohesive, non-cohesive and free-flowing excipient was studied using two types of mixers, cylindrical shear and V-shaped tumbling.

TL;DR: In this paper, Monte Carlo simulation is used to extend the simple model originally derived by Vahl and Kingma for the flow of powder through a rotating cylinder to include dispersion.

TL;DR: Measurments on powders using photoacoustic (PAS) and photothermal (PTS) spectroscopic techniques are described in this paper, which avail themselves of the heat generated in a sample upon irradiation, which can be used to analyse and identify the sample through its absorption spectrum.