1. Amirhossein (Amir) Alikhanzadeh
Supervisor: Murray J. Thomson
Combustion Research Laboratory, Department of Mechanical
and Industrial Engineering
University of Toronto, Toronto, Ontario, Canada
Investigation of the effects of beam scattering and
beam wandering on laser beams passing thorough the
off-gas duct of an Electric Arc Furnace (EAF)
Master of Applied Science Thesis Defense
University of Toronto, Ontario
December 10th , 2014

2. Project Overview
2
TDL unable to
penetrate EAF
off –gas duct
Beam scattering
due to collision
with dust particles
Literature review -
Model
Rayleigh
scattering
Mie scattering
Geometric
scattering
Experiment In lab
Beam wandering
due to turbulence
and temperature
gradient
Experiment
In lab
Vertical Flow reactor
(VFR)

3. 3
Motivation : Steel industry
- Uses primarily scrap steel
- Lower energy consumption
- Regulations on the emissions
- 12 to 14 Billion $ sale in Canada (2012)
- High production
- Recycling rate of 40 % to 60 % in
Canada (7 million tonnes recycled in
2012)
- 7.5 % of industrial energy use
BENCHMARKING ENERGY INTENSITY IN THE CANADIAN STEEL INDUSTRY
(Prepared by Natural resources Canada)
EAF 2002 Energy intensity indicator
(MJ/tonnes of Hot Rolled Product)

4. 4
Electric Arc Furnace – Process control
- Heats charged material by means of electric arc
- Consists of three holes plus a “fourth hole”  off-gas extraction
- Off-gas temperature of around 1400 degrees Celsius
Courtesy of Yuhui Sun [University of Toronto]

5. 5
Objective: How important is this
study? Zolo - SCAN
- Zolo-SCAN
- System developed for in-situ measurement
- Difficulty getting the beam over the path
length of the exhaust duct
- Critical Path Length; two reasons

6. 6
Objective: How important is this
study? LINDARC
- Based on TDLAS
- Water cooled rod
- Making readings at the centre
- Reasons similar to Zolo-SCAN

7. 7
Problems with the systems such as
LINDARC and Zolo-SCAN
Most of the issues come from having the rods:
- Dust accumulation
- Rod corrosion
- Damage to the equipment because of molten steel
- Bridging the gap (LINDARC) by means of molten steel
High maintenance expenditure

8. 8
Background: Light interaction with
medium
Light – medium
interaction
Attenuation
(Loss)
Absorption Scattering
Rayleigh
scattering
Mie scattering
Direction and
shape
Scintillation
Beam
wandering

9. 9
Background: What is beam
scattering?
Light interaction
with particles
Reflection (Light
deviated from its
original path
Refraction
Diffraction
Absorption
(Absorbed and
converted to heat)
Reflection
Refraction
Diffraction
Heat dissipation

10. 10
Scattering model: Mie theory
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 0.5 1 1.5 2 2.5 3 3.5
Volumefraction
Particle diameter (microns)
Particle size distribution (Evans Group)
S-A sample Dust sample
-
Mie Scattering
• Particle size is comparable to the
wavelength
• Not heavily dependant on the
wavelength change
• Particle size parameter: 𝑥 =
𝜋𝑑
λ

11. Scattering model: Literature
validation
Scattering coefficient in
literature
Scattering coefficient
calculated with the model
11

12. Scattering model: Model implications – Changing
particle sizes and their distribution
Constant scattering area
- Total scattering area is kept the same while constituent particles are varied in size and
subsequently concentration
- The assumed particle sizes are 0.5,1,1.5,2,2.5 µm in diameter
Concentration of 1.5 micron = 0
Concentration of 1.5 micron = 25
Concentration of 1.5 micons = 50
Concentration of 1.5 micons = 75
Concentration of 1.5 micons = 100
0
5E+09
1E+10
1.5E+10
2E+10
2.5E+10
0.5 1
1.5
2
2.5
0.00E+00
2.50E+09
5.00E+09
7.50E+09
1.00E+10
Numberofparticles/cubicmeter
Particle size in microns 12

13. Scattering model: Model implications – Effects of
changing particle sizes and their distribution on light
transmission
13
- How NIR transmission is affected when the wavelength is close to the dominant particle sizes
0.5
0.6
0.7
0.8
0.9
1
0 25 50 75 100
I/I0
Percentage of 1.5 micron particles
Light transmission with change in particle size and concentration
VIS - Transmission
NIR- Transmission
MIR- Transmission

14. Scattering model: Model implications –
Effect of refractive index
0.8
0.9
1
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9
LIGHTTRANSMISSION
REFRACTIVE INDEX
Light Transmission (VIS)
Light Transmission (NIR)
Light Transmission (MIR)
14

15. 15
Scattering Experiment:
Description/Purpose
Vibration motors
Different size sieve
VIS source
MIR source
NIR sourceNIR detector
VIS detector
MIR detector
Collecting foil
Particles
Vibration motor
Sieve
Particles
15 cm
25cm25cm25cm25cm

16. 16
Scattering Experiment: Result
- Model could not be
fully verified with
experiments
- The experiment
showed that model
implications of less
scattering at long
wavelength is held
- Although only
qualitative
measurements for
mass, it can be seen
that more particles
means more
attenuation of light
0
25
50
75
100
Talc - 4.4 g Talc - 7.8 g Al2O3 - 6.6 g Al2O3 - 5.6 g
Attenuation
Test ( Particles used - mass dropped in one minute)
Light attenuation from particle scattering
VIS - %Attenuation
NIR - %Attenuation
MIR - %Attenuation

17. 17
Scattering model: Real particle sizes
- Malvern Spraytec
- Agglomeration of the particles is
evident by comparison to Evans’
result
Talc
Aluminum oxide
Jamie Loh [University of Toronto]

18. 18
Scattering : Conclusions
Particle size
distribution
Particle weight %
distribution
Particle refractive
index
Incident
wavelength
Predict how much beam
is lost due to scattering

19. 19
Beam wandering due to
turbulence?
Turbulence
Time Steps
- Varying Temperature, Density and
Index of refraction through
turbulence
- Amplitude fluctuations  Signal
fades
- Beam Wandering (Steering) –
Location movement
- or Scintillation  Distorted beam
shape
https://www.youtube.com/watch?v=VEFEQUY-KNA&list=LLSmktf7Lsrml6zbh078Zing&index=2

20. 20
Turbulence: Theory
- Kolmogorov theory of turbulence
- Energy flow starts from the outer scale and cascades
to smaller scale
- Act as small lenses
- Light beam of diameter bigger than the eddy would
refract and smaller than the eddy broadens the
beam; the net effect is a combination of the two
Energy injection
Energy transfer
Energy dissipation
Lo
lo

21. 21
Beam wandering: Effects of
refractive index change
https://www.youtube.com/watch?v=bW6EcCcjFW0&index=4&list=PLKvrYlykYnYvXdpiffFtD2-jUrv7_2NJE
Laser Detector
Laser
Detector
LASER
LASER
DetectorDetector
a)
b)
Time
Lightbeampower
Lightbeampower
Time
Light beam Detector
(a)
Time
Lightbeampower
Lightbeampower
Time
Light beam Detector
(b)
Time
Lightbeampower
Lightbeampower
Time
Light beam
Detector
(a)

22. 22
Beam wander: Small-scale
experiment
- To see how temperature gradient changes the beam
NIR
laserVIS
laser
Photo detectors
Time
Temperature

23. Beam wander: Small-scale
experiment implication
Amplitude = 0.0352* T
R² = 0.9825
0
5
10
15
20
0 100 200 300 400 500
Amplitude(cm)
Temp (oC)
DEVIATION FROM CENTRE OF THE DETECTOR VS HOT
PLATE SURFACE TEMPERATURE
23
- Linear relationship between temperature (gradient) and deviation from the detector

24. 24
Beam wandering: Experiment goal
- The experiment was designed to test if adding a large collecting lens
would improve the signal
Light beam Detector
Light beam Detector
(a)
(b)
Light beam Detector
Light beam Detector
(a)
(b)

25. 25
Beam wander: Experiment at the
Vertical Flow Reactor
Light beam
(VIS – NIR)
Detector movement
Front view
Collecting lens
Detector
(a)(b)
Plano convex lenses
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
- Mapping the intensity of laser received
at the detector
Light beam
Detector movement
Front view
Collecting lens
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
Collec
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
Co
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
Collec
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
Collec
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
Collec
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
Co
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
Co
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
Co
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
(VIS – NIR)
Detector movement
Front view
(b)
Detector movement
Front view
2.5 cm
2.5 cm 2.5 cm
- 2.5 cm
(a)
Light beam
Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (b)
Light beam
Detector movement
Front view
((b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a) (
Light beam
(VIS – NIR)
Detector movement
Front view
(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a)
Light beam
Detector movement
Front view
(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a)
Light beam
(VIS – NIR)
Detector movement
Front view
(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a)
Light beam
Detector movement
Front view
(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
- 2.5 cm
(a)
Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)
Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)
Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)
Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)Detector movement
Front view
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)
Detector movement
Front view
Collecting
(a)(b)
Detector movement
Front view
2.5 cm
5 cm 2.5 cm
(a) (b)Detector movement
Front view
Collect
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)Detector movement
Front view
Collecting lens
(a)(b)
Detector movement
Front view
2.5 cm
m 2.5 cm
(a) (b)Detector movement
Front view
Collecting l
(a)(b)
Detector movement
Front view
2.5 cm
- 2.5 cm 2.5 cm
(a) (b)Detector movement
Front view
Collecting lens
(a)(b)
Detector movement
Front view
2.5 cm
2.5 cm
(a) (b)Detector movement
Front view
Collecting lens
(a)(b)
Detector movement
Front view
2.5 cm
2.5 cm 2.5 cm
(a) (b)Detector movement
Front view
Collecting lens
(a)(b)
Detector movement
Front view
2.5 cm
2.5 cm
) (b)Detector movement
Front view
Collecting lens
(a)(b)
Detector movement
Front view
2.5 cm
cm 2.5 cm
(a) (b)

26. 26
Beam wander: Near Infrared Laser
signal strength map on Vertical axes
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-15 -10 -5 0 5 10 15
INTENSITY(V)
POSITION (MM)
NO HEAT - NO LENS HEATED - NO LENS
0
2
4
6
8
10
12
-6 -4 -2 0 2 4 6
INTENSITY(V)
POSITION (MM)
NO HEAT- WITH LENS HEATED - WITH LENS
Vertical axis – No lens Vertical axis – With lens
41 % drop
9 % drop
16 mm
6 mm

27. 27
Beam wander: Near Infrared Laser
signal strength map on Horizontal
0
2
4
6
8
10
12
-12 -7 -2 3 8
Intensity(V)
Horizontal Position (mm)
NO HEAT - NO
LENS
NO HEAT- WITH
LENS
HEATED - NO
LENS
HEATED - WITH
LENS

28. Beam wander: Visible Laser signal
strength map on Horizontal axis
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
1.35
-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
Intensity(V)
Horizontal Position (mm)
NO HEAT - NO LENS
HEATED - NO LENS
HEATED - WITH LENS
28

29. Beam wander: Visible Laser signal
strength map on Vertical axis
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
1.35
-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8
Intensity(V)
Vertical Position (mm)
NO HEAT - NO LENS
HEATED - NO LENS
HEATED - WITH LENS
29

30. 30
Beam wander: Frequency of
occurrence - Method
- The “aperture” is fixed in position and the intensity of light inside the aperture is received
by the detector
http://www.pnas.org/content/111/34/12320.full

31. Beam wander: Frequency of
occurrence - Result
0000
25
75
0 0.00.00.00.0
34.2
60.7
4.7
0
25
50
75
100
1.4-1.51.3-1.41.2-1.31.1-1.21.0-1.10.9-10.8-0.9
PercentageofdatapointsinIntensitybin
Intensity (V)
VIS Source:Frequency of occurance
No Heat No Lens
Heated No Lens
Heated with Lens
31
- Adding the lens  Higher power and peak, narrower profile

32. Beam wander: Frequency of
occurrence - Result
- Adding the lens  Higher power and peak, narrower profile
0.000.000.000.000.000.000.000.000.000.000.00
37.25
59.80
2.94
0.00
0
20
40
60
80
100
NIR Source:Frequency of occurance
Mean centre data (NHNL)
Mean centre data (NHL)
Mean centre data (HNL)
Mean centre data (HL)
32

33. 33
Conclusion
Large collecting lens, continuous
monitoring of the temperature in
the medium for modeling
(Reduce fluctuation and improve signal strength)
Current wavelengths are mainly
Infra red; limitation in terms of
the dust particles that exist in the
off-gas duct
Zolo-SCAN, LINDARC: Define a
Critical Path Length, need robust
system, high maintenance
Moving to a longer wavelengths;
THz is a possible solution
(Minimize the effects of scattering)
Stronger signal
at the detector

34. 34
Suggestions for future work
Improvements
on this study
Model Experiment

35. 35
Future work: Model
Adding Rayleigh
and Geometric
scattering to
improve dynamic
range for particle
sizes
Find an
experimental
relationship
between the
concentration and
light transmission

36. 36
Future work: Experiment
Model the
conditions of
the turbulent
medium
Real –time
continuous
measurements of
the temperatures
inside the medium
Need improvement
in characterizing the
particle sizes and
distributions for the
scattering
predictions

37. 37
Acknowledgments
- Dr.Zhenyou Wang (University of Toronto)
- Dr. Arathi Padmanabhan (University of Toronto)
- Prof.Murray Thomson (University of Toronto)

38. 38
Questions

39. 39
Background: Rayleigh scattering
- Responsible for blue sky
- Responsible for red sunset
- Preferential scattering
Rayleigh Scattering
• Particulate much smaller than wavelength
• RS ∝ 𝑑6
• RS ∝ λ−4

40. Scattering coefficient
- Responsible for blue sky
- Responsible for red sunset
- Preferential scattering
D-MIR D-NIR D-VIS
3.237212 1.480141 0.603516
0
2
4
6
1 1.2 1.4 1.6 1.8 2
SCATTERINGCOEFFICIENT
REFRACTIVE INDEX CHANGE FOR X=3
Scattering coefficient - x=2.5
Scattering coefficient - x=3
AVG
40