fractionated treatment and separate refining of pulp to reduce energy consumption
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Fractionated treatment and
separate refining of pulp to reduce
energy consumption
17.11.2015
Rafael Giner Tovar
Institute of Pulp, Paper and Fibre Technology
1
Outline
• Introduction
• Fractionation and separate refining
• Results
• Conclusions
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Introduction Why refining?
• Refining
Process engineering → milling process
Pulp and paper industry → forming process
• Through refining, fibres are…
internally fibrillated → higher flexibility
externally fibrillated → fines production, higher bonding area
long fibres are shortened
ideally, short fibres are not affected
better fibre-fibre bonding
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• Refining needed in stock preparation, improving
fibre-fibre bonding ability
sheet formation
physical properties of the final product
• Unrefined pulp
lower sheet strength
rough surface
• Chemical and mechanical pulp need to be refined before they
become suitable for papermaking
Refining can represent up to 60% of the total power consumption
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4 Introduction Why refining?
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5 Introduction Thermomechanical Pulp (TMP) Plant
Outline
• Introduction
• Fractionation and separate refining
• Results
• Conclusions
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Fractionation and separate refining
• Fractionation is used to separate pulp into fine and coarse fraction
• Fine fraction
can have higher tensile strength than the coarse fraction
their properties do not improve through refining
• Coarse fraction
only the coarse fraction needs to be refined
refining only coarse fraction energy consumption could be
reduced
• Different types of fractionation devices available
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Fractionation and separate refining Types of refiners
• Lab scale
Jokro mill
PFI Mill
Valley Beater
• Industrial refiner (e.g)
Voith Sulzer Twinflo E
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(PFI Mill, Frank-PTI)
(Valley Beater, Frank-PTI)
(Jokro Mill, Frank-PTI)
Fractionation and separate refining Fractionation on the lab scale
Preparation of the sample
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Mesh 16
Mesh 30
Mesh 50
Mesh 200
Fines Fine fraction
Coarse
fraction
Bauer McNett
1. Refining of the entire sample (reference)
2. Refining of the coarse fraction
3. Refining of the fine fraction
• Refining performed using a Jokro Mill
600 rpm in desintegrator
20 minutes, 150 rpm
240 rpm in desintegrator
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10 Fractionation and separate refining Refining on the lab scale
• Preparation of handsheets (Rapid-Köthen)
• Determination of properties such as thickness/density, tensile
strength, beating degree (°SR), air permeability
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Coarse
Mesh (16)
Fine Mesh
(30,50,200)
Fines
(<200) BrittJar
Jokro-
mill
Mixture
representing
whole pulp
Sheet-
forming
Fractionation and separate refining Sheet forming and mechanical testing
Refining of the coarse fraction
Outline
• Introduction
• Fractionation and separate refining
• Results
• Conclusions
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0
20
40
60
80
100
120
140
160
180
Thic
kness (
µm
)
Thickness
Unrefined
Entire sample
Coarse fraction refined
Fine fraction refined
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Bre
akin
g lengh (
m)
Breaking length
Unrefined
Entire sample
Coarse fraction refined
Fine fraction refined
0
2
4
6
8
10
12
14
16
18
°SR
Schopper-Riegler
Unrefined
Entire sample
Coarse fraction
Fine fraction
0
1000
2000
3000
4000
5000
6000
Air p
erm
eabili
ty (
ml/m
in)
Air permeability
Unrefined
Entire sample
Coarse fraction refined
Fine fraction
Outline
• Introduction
• Fractionation and separate refining
• Results
• Conclusions
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Conclusions
• Refining improves the paper properties
• Promising results when the coarse fraction is refined compared to
refining the whole sample
Similar effect on dewatering
Comparable results on thickness
Comparable results on air permeability
40% less material refined → similar increase in breaking length → energy
savings
• Future trials using different pulps and coarse/fine fraction ratios
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