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The first lecture in the module Particle Technology, delivered to second year students who have already studied basic fluid mechanics. Some applications of Particle Technology are described, in industry and nature, and particle size analysis and means of representing the data. The format for the laboratory classes for the module and their reports are covered.
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Particle TechnologyProfessor Richard [email protected]
Watch this lecture at http://www.vimeo.com/9936959.
Also visit; http://www.midlandit.co.uk/particletechnology.htm
for further resources.
Format
1 Lecture per week, 1 Problem Class – tutorials & self
study 1 hour on: Moodle/Learn – tutorials &
self study Laboratories (oral, report &
experimental) Two hour exam (75% module mark)
Exam
Two hour exam 3 questions from 5 Question 1 obligatory PSD Previous answers old papers on
Learn Tutorial problems (& book on:
www.particles.org.uk)
Lecture topics
Particles & Characterisation Dilute particulate systems Hindered systems Fluid flow in porous
media/Fluidisation Filtration
Membranes & colloids
Emulsions, surfaces & dispersions
Centrifugal separation
Two phase flow, rheology & powders
Gas cleaning Comminution &
mixing
Problem Classes
See: http://learn.lboro.ac.uk/ www.particles.org.uk References:
• 614.83 , 620.43, 621.54, 660.283 & 660.2842
• Coulson & Richardson Vol 2; • Fundamentals of Particle Tech – free pdf
book • Rhodes, Introduction to Particle
Technology
Particles & Characterisation
Introduction to Particle Technology Equivalent spherical diameters Shape factors Specific surface area Size ranges and grades Normalised distributions Particle size analysis
What is Particle Technology?
Study, characterisation, prediction of properties during the processing of particle dispersions ranging down to sub-microscopic material. It is the extension of mechanics (fluids and solids) into particle containing systems. The term 'particles' includes liquid emulsions, drops, foams, oils, dusts, bubbles, fogs, etc…
N.B. The definition of a micron, andhuman hair is 70 microns,blood cells are 8 microns,bacteria are bigger than 0.2 microns- all are particles
What’s the problem?
Viscosity Density Molecular size Heat capacity Flow regime Easy to define for a fluid How do these change with particles?
Equivalent spherical diameters
To equate some property of the irregular shaped particle to a sphere with the same property, e.g. same volume as particle:Has the same
volume as a sphere - hence:
3
6 VxV
Note use of x for diameter.
Equivalent spherical diameters
It is possible to measure volume of a particle by displacement, or electrical resistance of suspension, and equate to that of sphere of same volume.
Some other equivalences include projected area, surface area and mass 2
4 Ap xA
2SAS xA 3
6Mass Vx
Shape factors
Volume of a sphere:
Hence volume shape factor is:
The volume shape factor for a cube is?
3
6 VxV
6
Specific surface
Specific surface area per unit volume - usually abbreviated to specific surface is the surface area over volume:
Hence Sv=6/x as is commonly used.
Use density to convert to SMASS
3
2
6x
xSv
Size ranges and grades
Size ranges and grades
Size ranges and grades
Normalised distributions
Normalised distributions
Normalised distributions
Normalised distributions
Normalised distributions
Normalised distributions
Normalised distributions
N (x)3n (x)3
P artic le d iam eterP artic le d iam eter00
x m axxm ax
Normalised distributions
0
50
100 %
1 10 100 1000
Particle diam eter, m .
MALVERN
Clarcel/calcite suspension
Normalised distributions
18816214012110489.977.566.957.749.842.937.13227.623.820.5
10010010010010010099.999.799.699.498.897.394.791.58884.
0000000.10.20.10.20.61.52.63.23.53.8
17.715.313.211.49.88.57.36.35.44.74.13.532.62.21.9
79.874.167.460.553.446.138.8322620.715.811.57.95.33.82.4
4.45.76.76.97.17.37.36.865.34.933.62.61.51.4
Size Sizem icrons m icronsunder under
% %in band in band
Median size 9.2 m
Specific surface: 0.944x105 m-1
Sauter mean diameter: 6.4 m
Normalised distributions
Particle size analysis
All techniques measure property and relate it to the equivalent spherical diameter.
Select your technique to be the most appropriate for the end use of the data.
The Coulter Counter
The image above is provided by Beatop (OMEC) Instruments Limited. As found at Beatop (OMEC) Instruments Limited http://www.beatop.com/Particle_Counter/principle_illustration.html
Particle size analysis
Malvern Sedimentation/Sedigraph
Particle size analysis
0
20
40
60
80
100 C
um
ula
tiv
e m
ass
un
de
rsiz
e,
%.
1 10 100
Particle diameter, m icrons.
Median sizes:laser diffraction 19.8Coulter 13.5sedim entation 18.5
laser d iffraction sed im en ta tion C oulter
Summary
Equivalent spherical diameters Shape factors Specific surface area Size ranges and grades Normalised distributions Particle size analysis
Particle Tech Labs
Think design not laboratory Problem given by boss Might use Perry, C&R 6, etc. But lab exp to check model,
equations… Model could be good, just your
material… Report to boss ‘model no good’ is
NOT GOOD ENOUGH, so what – we still need it
Particle Tech Labs
So, design is it over or under? Does dodgy model matter? How to improve MODEL, not
experiment 2nd week, you tell us what you want
to do Repeating experiments only checks
on reproducibility of experiment, nothing else
Data analysis – assume data until known
Particle Tech Labs
References, use Harvard system and minus 6 marks for a Bibliography rather than a Reference section – minus 4 for no references at all. For example,
Bloggs, F., 2008, An anti-gravity machine, Journal of Good Ideas, 123, pp 22-33.
Orals: use PICTURES, do NOT derive equations. Do show flow diagram, etc.
This resource was created by Loughborough University and released as an open educational resource through the Open Engineering Resources project of the HE Academy Engineering Subject Centre. The Open Engineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme.
© 2009 Loughborough University
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