Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.0 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering 6. Design and selection of flow promotion devices 6.1 Flow additives (glidants and lubricants) 6.2 Size enlargement (agglomeration) 6.3 Flow promotion devices …
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.1 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
Measures and Flow Promotion Devices to avoid Bridging and Chanelling
Flow promotion devices objectives
Increas-ing flow channel
Avoid channel-
ling
Avoid bridging
Improve flowability of powder
Flow additives (anti-caking agents, glidants, lubricants…)
X X X
Size enlargement (agglomeration, pelletizing, tabletting)
X X X
Wall liners and coatings
Slippery paints, wall coatings X X - Rigid plates X X - Flexible walls (X) (X) X
Rigid inserts Cone, roof, beams, grid, bin X X - Pneumatic flow promo-tion devices
Continous aeration (pneumatic bottom or bin)
X X X
Bin cushion, aeration tube, box, whistle
- (X) X
Rapid aeration in batch (nozzles, lance, cannon)
- X X
Gas shocks waves by explosions - X X Oscillating devices
External vibrator, rapper, knocker - (X) X Internal vibrating grid or cone (X) (X) X Soil penetration rocket - - X Oscillating bins X X X
Rotating devices
Flexible arm agitator - (X) X Beam, arm, plough, plate agitator (X) - X paddle shaft (X) - X
Feeders with flow promotion function
Arm agitators in convergent or divergent hoppers
X X X
Rotary plough feeder (bunker dis-charge wagon)
X X X
Transverse driven screw feeder X X X (X) partially effective
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.2 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering 6.1 Flow additives (glidants and lubricants)
Effect of flow additive on heap formation of a technical herbicide
Herbicide with 0.3% Aerosil Herbicide with 0.9% Aerosil
Consolidation functions σc = f(σ1) and time consolidation function of herbicide
0
5
10
15
20
25
30
0 5 10 15 20 25 30
Eina
xial
e D
ruck
fest
igke
it σ
c[k
Pa]
Verfestigungsspannung σ1 [kPa]
0,3 Ma.-%
0,3 Ma.-% (24h)
0,9 Ma.-%
0,9 Ma.-% (24h)
ffc = 1
ffc = 2
ffc = 4
ffc = 10
ffc = σ1/σc flow function acc. to Jenike
Estimation of optimal guest particle size and their content:
Adhesion force ( )
⋅+
⋅+⋅= 2
0
g2
0g
hsls,H0H a
d2a2d
d24
CF
Guest particle size at FH0,min
0)d(d
dF
g
0H = →
−⋅= 2
adad 3
0
h0min,g
Load of guest particle at FH0,min
⋅−
⋅
ρ⋅
ρ⋅π=
⋅
⋅=µ
h
0
3/2
h
0
h,s
g,s
h
ggg d
a2da
2m2mn
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.3 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
6.2 Agglomeration - Size Enlargement
Operation principles of agglomeration processes: a) tumble agglomeration (growth or agitation agglomeration)
pelletizing
A – feed material (for agglomeration), Q heat flow
b) press agglomeration (compaction) in partially open or closed die
• continuous sheets (ribbon)
• solid forms (tablets, briquettes)
c) sintering (thermal process)
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.4 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
Tumble Agglomeration (Pelletizing) 1. Balling drum and balling pan
a) balling drum b) balling pan A feed material P green pellets W water
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.5 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
Press Agglomeration Operation principles of press agglomeration : a) b) c)
a) in a closed die
b) in a open die
c) by roller pressure
A feed
B agglomerate
FP compaction or press force
FR wall friction force in the die
channel
h punch stroke length
l filling level (not compacted)
s thickness of compacted
material
k compaction (k=l/s)
β1 half of nip angle
1 punch
2 pressing die
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.6 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
pp
d) Plastic deformation of particles to create large contact areas
f) Plastic deformation of entire tablet
e) Breakage of edges, particle breakage, pore filling
p
p
b) Elastic-plastic contact deformation
a) Feed of loose packing
c) Pore filling by fine particles
p
h0
h(t)
h(t)
h(t)
h(t)
h(t)
Microprocesses and deformation mechanism at powder press agglomeration (compaction)
Compaction function of cohesive powder
com
pact
stre
ngth
lg(
σ T i
n M
Pa)
compaction pressure lg(p in M Pa)10-3
Tablet, briquette or ribbon strength σT
unia
xial
com
pres
sive s
tren
gth
σc
consolidation stress σ10
σc = a1 · σ1 + σ c,0
For hopper design
σT= f(p)
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.7 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering 6.3 Flow promotion devices
Lining of BinsMaterial data of ultrahigh-molecular weight polyethylen
fastening
rounded edge profiles promote mass flow
no bulging bolts or edges!
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.8 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
Rigid Hopper Inserts
a) before
b
Θ
ΘG, con
b) Plate insert
b
bmin
Θ
c) Cone insert
ΘG
bmin, wedge
bmin, con
ΘG, wedge
d) Bin insert ("Binsert")
bmin, wedge
2 · ΘG, con
bmin, con
ΘG, con
ΘGΘG
ΘG hopper angle limit of the flow zone
flow zone
deadzone
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.9 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
Pneumatic Flow Promotion Devices
Druckluft
Druckluft
Druckluft
Druck-luft
Ruhe-stellung
Druckluft
Ruhe-stellung
Druckluft
Druckluft
poröser Boden
Druckluft
a) Fluidisation of whole bin b) Aeration bottom
c) Aeration box d) Bin wall cushion
e) Porous aeration tube f) Aeration whistle
g) Movable air lance h) Air cannon
porous bottom compressed air
compressed aircompressed air
compressed air
compressed air
compressed air
at rest
at rest
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.10 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
Air Pressure Shock Device (Air Cannon)
channelling piping (ratholing) bridging in hopperr in shaft
filling
compressed air
shock waveoutflow
rapid releasing valve
Arrangement of air cannons:
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.11 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
Vibrating discharge aids
a) Unbalanced motor at hopper wall (dashed lines: wall oscillations at high-frequency excitation f > 100 Hz)
b) Silo with flexible connected vibrating
hopper and conical deflector (Δx < 4 mm, f < 25 Hz)
Additional options for convex deflector and/or oscillating inserts (rods, cages, screens, flexible grids):
c) Matcon-Bules as
“valve” with low-ered cone (left) and with lifted and vi-brating cone by pneumatic excita-tion as discharge aid (right)
Kollmann, Th.: Schwingungsinduziertes Fließen feinstkörniger, kohäsiver Pulver, Diss. Otto-von-Guericke-Universität Magdeburg 2002
Fig_PC&P_6 Lecture Product Characterization and Processing of Pharmaceutical Particulate Solids, flow promotion devices, Jürgen Tomas 31.05.2013
Figure 6.12 Prof. Dr.-Ing. habil. J. Tomas – chair for Mechanical Process Engineering
Arrangement of Discharge Aids at Time Consolidations
1. Minimum discharge width versus storage time at rest
bmin(tmax)
bmin(t1)
bmin,0
b2
0 t1 tmaxstorage time t
outle
t wid
th b
min
bmin(t) = bmin,0 + b∞· [1 - exp(- )] tt63
_
b) discharge aid necessary for t > t1
bmin(tmax)
bmin(t1)a) no discharge aid necessary
bmin(tmax)
2. Outlet design
no bridging for t < tmax
0
bmin(t1)
bmin(tmax)
bmin,0
b2
no bridging for t < t1
no bridging for t = 0
bridgingho
pper
hei
ght
y
bmin,0
bmin(tmax)
bmin(t1)c) discharge aid necessary for t > 0
b2
bmin(tmax)
bmin(t1)
bmin,0
d) discharge aid necessary for t > 0
e) discharge aid always necessary
see Schulze, D., Austragorgane und Austraghilfen, Chem.-Ing.-Techn. 65 (1993) 48-57