Showing papers in "Powder Technology in 2003"

TL;DR: In this article, a frictional-kinetic rheological model for dense assemblies of solids in a gas-particle mixture is described, which treats the kinetic and frictional stresses additively.

TL;DR: In this paper, a simulation of a freely bubbling bed of fluid catalytic cracking (FCC) catalyst operating at superficial gas velocities in the range of 0.05 to 0.20 m/s, using the two-fluid computational fluid dynamics (CFD) code Multiphase Flow with Interphase eXchanges (MFIX).

TL;DR: In this paper, an approach to quantify the grinding behavior of different materials is presented, based on a dimensional analysis and on fracture mechanical considerations, two material parameters, fMat. and Wm,min, are derived theoretically.

TL;DR: In this paper, the effect of physicochemical and process-related variables such as the excess gas velocity, atomizer location, liquid flow rate and concentration, and atomizing air flow rate on the growth of agglomerates was investigated.

TL;DR: In this paper, a whole-field, nonintrusive digital image analysis technique has been developed which enables measurement of bed expansion and segregation dynamics of coloured particles in dense gas-fluidised beds.

TL;DR: In this paper, the die compaction of pharmaceutical powders using a variable parameter Drucker-Prager type cap model was analyzed using a die instrumented with radial pressure sensors, which was also used to measure the coefficient of friction between powder and die wall.

TL;DR: In this article, a tabletop X-ray computed tomography (XRCT) system with a resolution of about 4 μm was used to characterize some pharmaceutical granules, showing that the pore network of individual granules comprises relatively large cavities connected by narrow pore necks.

TL;DR: In this article, the effect of shape in the results obtained using the electrical sensing zone method (ESZ) and the laser diffraction (LD) has been investigated using dynamic image analysis (DIA).

TL;DR: In this article, the relationship between porosity and interparticle forces for mono-sized spheres is quantified for two systems: packing of wet coarse spheres and packing of dry fine spheres where the dominant force is the van der Waals force.

TL;DR: In this article, the Monte Carlo method is used for simulating granular systems of spherocylindrical particles and porosities, calculated for simulated monodispersed beds, are presented as functions of particle elongation.

TL;DR: In this paper, a joint research project between the Technical University of Braunschweig and the technical University of Munchen investigates the possibilities for the production of stable product suspensions in a particle size range smaller than 100 nm.

TL;DR: The fluidization behavior of binary mixture differing in size in the gas bubbling fluidized bed is experimentally and theoretically studied in this paper, where the segregation phenomena are analyzed, and the relevancy of the pressure drop profile of the binary mixture to the definition of its minimum fluidization velocity is discussed.

TL;DR: In this paper, the authors studied the flow of particles in a horizontal rotating drum based on the results generated by the Distinct Element Method (DEM), which is comparable to those measured by means of Positron Emission Particle Tracking (PEPT), with a drum being 100 mm in diameter, 35% filled by spheres of 3 mm diameter and rotating at a speed from 10 to 65 rpm.

TL;DR: In this paper, the authors describe the rheological behavior of powders in the intermediate regime lying between the slow and rapid flow regimes, and derive an expression for the average stress that reduces to the quasi-static flow limit when fluctuations go to zero while, in the limit of large fluctuations, a liquid-like, viscous character is manifested by the bulk powder.

TL;DR: In this paper, a Cohesive Discrete Element Method (CDEM) was used to investigate the internal tensile stress and the tensile strength and shear strength of fine, cohesive granular materials.

TL;DR: In this paper, the authors focus on the agglomerate damage due to oblique impact on walls, as this is a common damage process during pneumatic conveying and size reduction in pin mills.

TL;DR: In this article, a mathematical investigation of particle motion on an inclined screening chute using the discrete element method (DEM) is presented, where special attention is paid to the implementation of an apertured boundary and the algorithm for allowing particles to pass through apertures or to rebound when approaching the screen surface.

TL;DR: In this paper, spherical agglomerated crystals of ascorbic acid with improved compactibility for direct tableting were successfully engineered by the spherical crystallization technique, where the micromeritic properties, such as flowability and packability, were preferably improved.

TL;DR: In this paper, a model shoe system for the study of powder flow in air and vacuum has been developed, which allows the flow and rearrangement of the powder to be observed using a high-speed video system.

TL;DR: In this paper, the influence of the dispersion technique on the sintering behavior of W-Cu composites is investigated, and a powder consisting of composite particles has an optimal Cu dispersion and a very fine tungsten phase.

TL;DR: In this article, the rolling theory for granular solids proposed by J.R. Johanson in the 1960s, later trials utilizing slab method and newly developed final element models are compared in terms of efficiency and accuracy of predicting the course of basic process variables.

TL;DR: In this article, a relationship between the underlying particle-size distribution and the measured chord-length distribution from a Lasentec Focused Beam Reflectance Measurement (FBRM) instrument is derived.

TL;DR: In this article, an exponential model is proposed for evaluating the effective viscosity of a particle-fluid mixture, which is restricted to the dilute condition without effects of dynamic particle interactions and fluid turbulence.

TL;DR: Microcapsules wall is made of polyurea and release rates monitored by pH-measuring in the disinfectant solution, are found to be very low, allowing a good compatibility of insecticide and disinfectant.

TL;DR: In this paper, a systematic evaluation of the possible magnitudes of electrostatic forces and van der Waals forces is presented, based on theoretical analysis and existing experimental data, which indicates that the electrostatic adhesion on a charged particle under the condition that it can be detached by an applied electric field is likely to be greater than van derWaals forces.

TL;DR: In this article, the main features of roll compactor design are reviewed and the interaction between feeder and compact quality is demonstrated, and the strong link of the stress distribution of the compact issued from a roll press fed by a single screw with the periodicity of the screw was demonstrated and explained.

TL;DR: In this paper, the authors present direct measurements of particle-particle and particle-surface interactions in the gas phase carried out with an atomic force microscope (AFM) and special emphasis is given to a proper statistical treatment of the data.

TL;DR: In this paper, a small-size spouted bed with a porous draft tube was employed to obtain hydrodynamic data of binary mixtures of glass beads for a range of operating conditions and design factors.

TL;DR: In this article, the authors investigated the possible gas leakages in a chemical-looping combustion (CLC) system and found that a typical leakage from the pot-seal into the fuel reactor was 6%, which corresponds to 0.3% of the total air added to the system, and would give a dilution of the CO 2 produced by approximately 6% air.

TL;DR: In this article, the adhesion forces by means of atomic force microscopy (AFM) measurements complemented by centrifugal detachment measurements in an ultracentrifuge were investigated.