Post on 26-May-2015
1 LASENTEC
LASENTEC
The Scale-Up of Solid/Liquid Separations
The Role of Particle Size
Terry Redmond
James Ward
2 LASENTEC
Common Definitions
Filtrate Medium
Filter Cake
3 LASENTEC
Common Definitions
Medium Resistance (Rm)
Pressure (Pi)
Pressure (Pf)
Cake Resistance (Rc)
4 LASENTEC
Common Definitions
(Rm)
Pressure (Pi)
Pressure (Pf)
(Rc)
Filtrate Velocity (v)
)( mc
fi
RR
PPVelocity
WherePi = Initial PressurePf = Final PressureRc = Cake ResistanceRm = Media Resistance = Filtrate Viscosity
5 LASENTEC
Common Definitions
Filtrate Medium
Filter Cake
6 LASENTEC
Common Definitions
Filtrate Medium
Filter Cake
7 LASENTEC
Common Definitions
FiltrateMedium
Filter Cake AMRC /
WhereRc = Cake ResistancePf = Dry Mass of ParticlesA = Area = Specific Cake Resistance
8 LASENTEC
Common Definitions
FiltrateMedium
Filter Cake
Whereq = Volumetric FlowrateA = Filter Areav = Filterate VelocityP = Pressure Drop = Specific Cake Resistancec* = dry mass solid / vol filterateV = Volume = Filtrate viscosity
)*(
)(/
RmAVc
PAvAq
9 LASENTEC
Inverse Filter Leaf Test
VacuumSource
VacuumAdjust
Vacuum Gauge
Slurry
Filter Media
PA
Rm
PA
VcVt
)2(
*/
2
10 LASENTEC
Inverse Filter Leaf Test
PA
Rm
PA
VcVt
)2(
*/
2
t /
V
V
PA
Rm
)2(
*2 PA
c
11 LASENTEC
Filter Blinding - The Role of Fines
t /
V
V
Run 1
PA
Rm
12 LASENTEC
Inverse Filter Leaf Test
t /
V
V
Run 1
PA
Rm
13 LASENTEC
Inverse Filter Leaf Test
t /
V
V
Run 1
Run 2
PA
Rm
14 LASENTEC
Inverse Filter Leaf Test
t /
V
V
Run 1
Run 2
15 LASENTEC
Inverse Filter Leaf Test
t /
V
V
Run 1
Run 2
Run 3
16 LASENTEC
The Components of Alpha
17 LASENTEC
The Components of Alpha
p
pp VSK
3
21 1/
Where = Specific Cake ResistanceK = ConstantSp = Mean Particle Surface AreaVp = Mean Particle Volume = Porosity of Filter Cake
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A Focus on Particle Size
p
pp VSK
3
21 1/
524,000 µm3524,000 µm3Total volume
314,000 µm231,400 µm2Surface area
10 µm100 µmDiameter
1000 particles1 particleTotal number
BA
100B
A
19 LASENTEC
Alpha and the Real World
1.2 x 10^9
1.8 x 10^9
3.8 x 10^9
3.9 x 10^9
Specific Cake Resistance vs Mean Square Wt
y = -6.6689x + 68.984
R2 = 0.9144
0
10
20
30
40
50
60
70
0 1 2 3 4 5
Specific Cake Resistance
Mea
n S
qu
are
Wei
gh
The mean particle size decreases by 32% as the cake resistance increases by 325+%
20 LASENTEC
Another Example
Chord length distribution comparison
0
2
4
6
8
10
12
14
Chord length
Pop
ula
tion
%
Control
Ostwald, fast stir
21 LASENTEC
Another Example
Chord length distribution comparison
0
2
4
6
8
10
12
14
Chord length
Pop
ula
tion
%
Control
Ostwald, fast stir
Existing process (plant batches)
D-90 D-50 D-10 26.8m 9.0m 2.1m
Ostwald ripened (plant batches)
D-90 D-50 D-10 59.4m 18.8m 5.2m
No filter bed blindingeven after 16 batches
22 LASENTEC
Another Example
Chord length distribution comparison
0
2
4
6
8
10
12
14
Chord length
Pop
ula
tion
%
Control
Ostwald, fast stir
Existing process (plant batches)
D-90 D-50 D-10 26.8m 9.0m 2.1m
Ostwald ripened (plant batches)
D-90 D-50 D-10 59.4m 18.8m 5.2m
No filter bed blindingeven after 16 batches
In Summary• Particle attrition in crystallizer and filter dryer.
reduced, no slurry handling problems.
• Mean particle size doubled.
• Eliminated Fuji plate blinding, entirecampaign run without plate wash.
• Reduced process time by 3 hours (10%).
• Reduced labour by 120 operator hours/month.
• Increased monthly throughput from 20 batchesto 24 batches.
• FBRM paid for itself in 2 months.
23 LASENTEC
A Focus on Particle Size
p
pp VSK
3
21 1/
87.1B
A
37% Increase1,161,800µm3847,800µm2Total Surface Area
Decrease 3.3%96.7 µm100.0 µmVolume
mean diameter
Decrease 87.7%12.3 µm100.0 µmNumber
mean diameter
0%14,140,000 µm314,140,000 µm3Total volume
Increase 3700%1026 particles27 particlesTotal number
Relative changeAfter breakage of one particle
Initial particle system
(An 87% increase in Specific Cake Resistance)
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Conclusions
Building from Filtration Theory we were able to determine why particles are important to filtration scale-up
By developing the idea of Media Resistance and Filter area we were able to investigate how fines increase filter time by blinding
By looking into the components of Specific Cake Resistance we were able to explain why PSD and cake compressibility are important
We confirmed the literature equations to real world data sets
25 LASENTEC
Acknowledgements
Ron Washburn and Jon Hokinson for IT work
Cheryl Thom for transportation of instrumentation
Everyone at Mettler Toledo Millersville for the use of facilities and equipment