Doctoral Thesis

Limit Modes of Particulate Materials Classifiers

Main document 7.68 MB Thesis 3.6 MB

FSIDoctoral ThesisStudent: Ing. Martin AdamčíkAcad. year: 2017/2018

Leader: prof. Ing. Tomáš Svěrák, CSc.

Opponents: prof. Ing. František Štěpánek, Ph.D., doc. Ing. Roman Fekete, Ph.D.

With material science demands on ever smaller particle sizes, new approaches and effective methods of their classification are needed. Turbulent flow field patterns and particle trajectories inside of a dynamic air classifier are investigated. Increasing computing power together with new turbulence models and approaches to simulate complex fully turbulent problems by solving Navier-Stokes equations allows studying and capturing smaller flow structures and properties more accurately. Particles below 10 microns are more susceptible to smaller local vortexes and particle fates are therefore more dependent on these local structures. Area of focus are the conditions required for classification of particles with sizes below 10 microns as this size is at the limit of air classification method possibilities. CFD software and the latest knowledge in turbulence modelling are used to numerically simulate flow field inside a dynamic air classifier. Effects of varying operating parameters on flow patterns and discrete phase classification outputs are investigated. Experimental verification of the simulated flow fields includes advanced imaging method (PIV) measurement of flow velocity and is used to visualize flow field structures in the classifier rotor blade passageway region. Predicted particle trajectories and their fates are experimentally verified by classification trials carried out on dynamic air classifier and the particle distribution curves are established by laser diffraction method. Tromp curves and efficiency of classification process are studied.

Language

English

State

Defended (thesis was successfully defended)

Hodnocení známka

P

Faculty

Department

Study branch

Applied Mechanics

Classification by opponent
prof. Ing. František Štěpánek, Ph.D.

viz. posudek v pdf.



File inserted by the reviewer Size
posudek_PhD_Adamcik_2017 (1).pdf [.pdf] 298.9 kB B

Classification by opponent
doc. Ing. Roman Fekete, Ph.D.

viz. posudek v pdf.



File inserted by the reviewer Size
oponentsky posudok dizertacnej prace ADAMCIK.pdf [.pdf] 111.15 kB B

Objectives which should be achieve

•    Design and realization of trajectories measurement and granulometry analysis of major flows of very fine particulate materials in the latest generation of dynamic air classifiers
•    Modelling of particle motion of very fine particulate materials in dynamic air classifiers by means of latest available numerical model apparatus
•    Opportunities of process and mechanical design modifications of dynamic air classifiers which would help overcome current granulometric limits of classification processes

Literature

Literatura:
Feng, Y., Liu, J., Liu, S. (2008). Effects of operating parameters on flow field in a rotor air classifier. In: Minerals Engineering, vol. 21, pp. 598-604.
Griffiths, W., D., Boysan, F. (1996). Computational fluid dynamics (CFD) and empirical modelling of the performance of a number of cyclone samplers. In: Journal of Aerosol Science, vol. 27, no. 2, pp. 281-304.
Holdich, R., G. Fundamentals of Particle Technology. Midland Information Technology and Publishing, 2002. ISBN 13: 9780954388102
Johansen, S., T., Silva, S., R. (1996). Some considerations regarding optimum flow fields for centrifugal air classification. In: International Journal of Mineral Processing, vol. 44-45, pp. 703-721.
Leschonski, K. (1996). Classification of particles in the submicron range in an impeller wheel air classifier. In: KONA Powder and Particle Journal, no. 14, pp. 52-60.

Keywords

Rotor air classifier, fine particle classification, Tromp curve, particle image velocimetry (PIV), laser diffraction method, numerical simulation CFD

Characteristics of thesis dilemmas

Synopsis:
•    Literature review of dynamic air classification of very fine particulate materials process
•    Design and modification of current dynamic air classifier allowing nonintrusive flow field velocity measurement and flow pattern visualization in active classification zones
•    Testing of measuring systems of the experimental setup
•    Measurements of separation efficiency in relation to rotor speed, feed rate and flow rate
•    Elaboration of experimental results by use of available mathematical models
•    Evaluation of data obtained experimentally and prediction of possibilities of overcoming current granulometric limits of dynamic air classifiers