The rheology of dense granular flows in a disc impeller high shear granulator

Khalilitehrani, Mohammad; Abrahamsson, Per; Rasmuson, Anders

doi:10.1016/j.powtec.2013.08.033

Cited by 13 publications

(9 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They showed that the powder rheology was mainly determined by the content of fines, and proposed a rheological model using mathematical modelling based on continuum mechanics. Based on experiments and CFD simulations, Khalilitehrani et al (2013;2015) studied the rheology of dense granular flows in a disc impeller high shear granulator. Remy et al (2009Remy et al ( , 2011 carried out stress analyses of particle flow in a rotating blade mixer using DEM.…”

Section: Introductionmentioning

confidence: 99%

Analysis of powder rheometry of FT4: Effect of air flow

Nan

Ghadiri

Wang

2017

Chemical Engineering Science

View full text Add to dashboard Cite

Understanding of particle flow behaviour as a function of strain rate is of great interest in many items of equipment of industrial processes, such as screw conveyors, impeller mixers, and feeders, etc. The traditional commercial instruments for bulk powder flow characterisation, such as shear cells, operate at low shear strain rates, and are not representative of unit operations under dynamic conditions. In recent years, the FT4 powder rheometer of Freeman Technology has emerged as a widely used technique for characterising particle flow under dynamic conditions of shear strain rate; yet little is known about its underlying powder mechanics. We analyse the effect of gas flow on the flow behaviour of cohesionless particles in FT4 both experimentally and by numerical simulations using the combined discrete element method (DEM) and computational fluid dynamics (CFD). The results show that the effect of gas flow on the flow energy could be described by the resultant fluid-induced drag on the particles above the blade position as the impeller penetrates the bed. The strain rate in front of the blade is mainly determined by the impeller tip speed, and is not sensitive to the gas flow and particle size. The flow energy correlates well with the shear stress in front of the blade. They both increase with the strain rate and are significantly reduced by the upward gas flow.

show abstract

Section: Introductionmentioning

confidence: 99%

Analysis of powder rheometry of FT4: Effect of air flow

Nan

Ghadiri

Wang

2017

Chemical Engineering Science

View full text Add to dashboard Cite

show abstract

“…However, in this work a new modeling framework is developed and the method it is not dependent on the specific choice of flow model. More accurate models for dense granular flows are needed and under development [13][14][15][16] for more reliable results. The present modeling framework is, however, not affected by the detailed flow modeling and in future work more accurate flow simulations can easily be incorporated.…”

Section: Figure 1 Side and Top View Of The Two Regions In The Granulmentioning

confidence: 99%

“…The continuum approach to particle flows in high shear granulation was first used by Darelius et al [9] and Ng et al [10]. This has further been studied by Abrahamsson et al [11][12][13] and developed by Khalilitehrani et al [14][15][16] which shows promising results but also a need for further development. The HSG process is a continuously changing system where the continuous changes in particle properties are bound to affect the flow field and vice versa.…”

Section: Introductionmentioning

confidence: 99%

Analysis of mesoscale effects in high-shear granulation through a computational fluid dynamics–population balance coupled compartment model

et al. 2018

View full text Add to dashboard Cite

In high shear granulation it has been pointed out that there is a need for meso-scale resolution and coupling between flow field information and the evolution of particle properties. In this article we develop a modelling framework that compartmentalizes the high shear granulation process based on process relevant parameters both in time and space. It is built up by a coupled flow field and population balance solver and is used to resolve and analyze the effects of meso-scales on the evolution of particle properties. A Diosna high shear mixer is modelled with micro crystalline cellulose powder as the granulation material. The analysis of the flow field solution and compartmentalization allows for a resolution of the stress and collision peak at the impeller blades. Different compartmentalizations were done showing the importance of resolving the impeller region, both for only aggregating systems and systems with breakage. An investigation on the time evolution of the flow field depending on the changing particle properties was also done, indicating the importance of resolving meso scale phenomena in time as well as space.

show abstract

“…As indicated above, in a typical HSG equipment there is coexistence of relatively dilute (solid volume fractions ranging from 0 to 0.5) and very dense regions (ranging from a volume fraction of 0.5 to the maximum packing of the material) [8,9]. The flow situation in the former region is most often described by the rapid flow theory, whereas in the latter, the quasi-static flow regime is assumed.…”

Section: Introductionmentioning

confidence: 99%

“…This approach focuses on the transition regime capturing the liquid-solid transition with a pressure-dependent yield stress determined for individual particle types and sizes from a set of flow experiments. The results show good potential, but the model is not capable of treating the rapid regime [8]. In Khalilitehrani et al [17], the framework was extended and combined with a rapid regime, kinetic theory of granular flow (KTGF), model with a transition criterion based on a regime determining inertial number.…”

Section: Introductionmentioning

confidence: 99%