Search results for "Fluidization"

Experimental analysis of bubble size distributions in 2D gas fluidized beds

2010

Abstract The present work focuses on the development of a novel statistical approach for the analysis of the behavior of a 2D fluidized bed operating under bubbling and slugging conditions. Experimental data were collected by means of a purposely built lab-scale 2D fluidized bed and an original digital image analysis technique (DIAT), allowing the acquisition of a number of data sufficient to perform a statistical analysis of bubble dynamics. In particular, measurements of bubble size distributions (BSD) along the bed were performed. The analysis allowed to characterize the shape of BSD for different particle systems and fluidization gas velocities; interestingly a bimodal shape of BSD is o…

A quantitative assessment of the effect of distributor type on particle circulation

1997

Abstract Garncarek's quantitative index of inhomogeneity has been used to compare the effect of distributor type on the degree of uniformity of solids mixing in a gas-fluidized bed assessed by following a tracer particle using the technique of Positron Emission Particle Tracking. The bed was a sand of 475 μm diameter fluidized at 2 U mf and contained within a column of 150 mm diameter. A porous and perforated plate distributor are compared. The index shows that tracer locations are generally more homogeneously distributed throughout the vertical section of the bed with the porous plate distributor. Behaviour varies with height and horizontal sections of the bed show that there is little dif…

Improvement of the techno-functional properties of pea proteins by microfluidization

2017

The use of pea (Pisum sativum (L.)) proteins in the food industry is still limited despite their good environmental sustainability, heath-oriented composition, reliable origin and stable price. However, one of the most important limitations is their low solubility which determines a number of their techno-functional properties. Microfluidization is a non-thermal emerging technology that may modify the structure and the techno-functional properties of pea proteins. Microfluidization combines high shear forces due to the stream speed and direction; impact forces from collisions with the walls and with the fluid itself; and turbulence inside the chamber. The objective of this work was to evalu…

Analysis of the bubbling behaviour of 2D gas solid fluidized beds

2008

Abstract In the field of gas–solid fluidization, bubbles, and all features regarding them, have a very great importance, as they significantly affect the process performance. Numerous experimental studies on bubbles, and their formation, evolution, and properties, have been performed in the past. These investigations appear particularly difficult, due to the nature of these systems, since the gas phase is distributed in both the bubble and the emulsion phase. Several experimental approaches have been developed to tackle this study. Among these, the Digital Image Analysis Technique purposely developed in Part I of the present work, based on the use of a video camera for monitoring the phenom…

On the use of a powder rheometer to characterize the powder flowability at low consolidation with torque resistances

2017

The Anton Paar Powder Cell was used to measure the torque necessary to rotate an impeller in beds of glass beads, sand and alumina powders aerated between no aeration to the minimum for fluidization. Measured torque values depend on the material tested, on the air flow rate applied, on the impeller depth and on the height of the impeller blade. The effect of the impeller depth is linear for low impeller depth and is less than linear at high depth values. A model was developed for the interpretation of the experimental results based on the idea that the material is shearing on the surface described by the impeller rotation. The model allows to estimate an effectiveness of the impeller in the…

Modeling of Magnetic-Field-Assisted Fluidization: Model Development and CFD Simulation of Magnetically Stabilized Fluidized Beds

2014

Magnetic-field-assisted fluidization is starting to be considered as a viable alternative to standard fluidized beds for those operations (such as particle separations, filtration, adsorption) in which the solid phase can be made of magnetic particles or, alternatively, the fluidizing agent is a ferro-fluid; thus the fluid bed responds to the action of magnetic fields, and stabilized fluidization regimes can be generated. One of the major difficulties to be tackled is the development of a predictive model capable of estimating the stabilized-to-bubbling transition velocity for a given magnetic field or, on the other hand, the magnetic field intensity required to stabilize the bed to a quies…

Aggregative behavior of cohesive magnesium carbonate powders during fluidization and aerated discharge

2014

In this paper we studied the aerated discharge of two magnesium carbonate powders differing in their average diameter and particle size distribution. These samples were characterized by means of fluidization experiments and rheology shear tests carried out in a rotating shear cell. In the hopper discharge experiments, besides the discharge rates and the mass of residual solids as a function of the aeration rate, the aggregative behavior was observed by means of photographic techniques. Solids aggregates were actually visible within the aerated beds of solids during the fluidization experiments and in the streams of the discharging solids. Experimental data on the powder flow properties and …

CFD prediction of bubble behavior in two-dimensional gas-solid fluidized beds

2009

This work focuses on the computational fluid dynamics (CFD) simulation of a laboratory-scale, two-dimensional fluidized bed and the relevant experiments in order to validate the prediction capability of the adopted codes and models. Both experimental and computational quantitative data were analyzed by means of an original digital image analysis technique, allowing for coherent comparison of computational and experimental results. In particular, this work analyzes the capability of the CFD simulations in predicting the fluctuating behavior of bubbling fluidized beds by means of frequency analysis of bubble-related phenomena.

Endosomal escape of canine parvovirus is assisted by membrane fluidization

2007

Gas-Fluidization Characteristics of Binary Mixtures of Particles in 2D Geometry

2012

The bubbling behaviour of fluidized beds has been thoroughly investigated in the last decades by means of several techniques, e.g. X-ray, Inductance, Resistance and Impedance based techniques, PIV. In recent years, Digital Image Analysis Techniques have shown their potential for accurate and cost effectively measurements.Most of the work related to bubble behaviour analysis deals with single-sized particles, while almost all industrial equipment operates with multi-sized particles. Although considerable work has been done in the past with focus on the analysis of the mixing-segregation behaviour and predictions of fluid dynamics regime transitions, a lack of knowledge still exists in the an…