Solids Handling in The Chemical Company
Dr. Hermann J. Feise1)
DI Thomas Letzelter2)
1) Science Relations 2) Process Systems Engineering
124.09.2012
2Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Solids Handling
Bulk Solids Characterization
Flow properties
Shear testers
Design of Storage Silos
Gravity fed storage systems
Flow promoting devices
Conveying of Bulk SolidsScrew conveyors, pneumatic conveying
Storing and Conveying of Bulk Solids
Being an Engineer in IndustryThe phone call
4:30 pm a customer calls
A new factory for our product „Powdery White“
Can you design the handling and shipping facilities for us?
YES, ......
Oh, and we have two grades, the fine and the instant product.
What question do you ask?
…
…
…
…
…
3Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
4Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Merrow (1986): “use of solids in a process is the most prominent factor causing delayed start-up”
Merrow (1998): “things did not get better”
delays of up to 18 month
process predictions of solids processes are inferior to fluid - processes
Particle technology is becoming increasingly important
The Role of Particle Technology
5Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Characterization of Bulk Solids: Bulk Solids are NOT like liquids
Gravel Baking powder
Vitamin powder Cement
Flow under gravity
Surface
Liquid: level
Bulk solids: angle of repose
Flow
Liquid: incompressible
Bulk solids: dilatant
Storgae pressure
Liquid: hydro static
Bulk solids: Janssen - effect
6Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Bulk Density – Bulk Solids Density
Flow properties, packaging
NOT a material constant
Depends on compaction, shaking, electro static conditions...
Tapped density / bulk density = Hausner number
Different countries – different standards – different bulk densities
Fülltrichter
Bodenklappe
MeßbecherPrüfgerät zur Schüttdichtebestimmung nach DIN 53466
Feed hopper
Knife valve
Graded cylinder
Device to determine the bulk density acc DIN 53466
7Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Bulk Solid PropertiesJanssen - Effect
= lateral stress ratio = h/v
x = external or wall friction angle
U = circumference
A = cross sectional area
Janssen (1895)
v A
v + dv) A
g b A dz
w U dz
h U dzdz
z
vh
Hydro static
xhw
zA
U
tan
e1UA
x tan
x
bv tan
g4D
w
8Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Reversion of frictional force!
v A
v + dv) A
g b A dz
w U dz
h U dzdz
z
v
1eUA z
AUx tan
x
bv tan
g
Bulk Solid PropertiesJanssen - Effect
9Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
250
200
150
100
50
00 100 200 300 400 500
Curve (1) Theoretical
Curve (2) ExperimentalMillet Vcon ? 30 mm/s
Forc
e -N
Column Length - mm
Force to Convey Millet seed Vertically through a 45 mm Acrylic Tube
© P. Arnold, U Wollongong
10Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Bulk Solid Properties: Virtual Experiment
1
1
22
fc
fc
Cylindrical sample with fricitonless supports
Compaction with lateral support Consolidation stress
1
Bulk solid density b
‚shear‘ No lateral support Uni-axial compressive
strength fcConsolidation Shear
11Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Bulk Solid Properties: Ringschergerät
Current industrial standard
Ring Shear Tester RST-01pc
Sample size: 200 bzw. 900ml
Automatic control
‚unlimited‘ travel
Several data points per sample
Suitable for products with x95< 4 mm
http://www.dietmar-schulze.de/fre.html
Lid
Tie Rod
Tie Rod
Guard Roll
Guard RollShear Cell
Cross Bar
Bulk Material
N
S
S
12Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
S
S
S
travel
travel
travel
Over-consolidated sampleMaterial flows under dilation
Well pre-sheared sampleMaterial flows under constand volume, no compaction
Under – consolidated sampleMaterial keeps compaction during shear
Shear test vs. Travel diagram
N =normal force, S = shear force
Shear Test
13Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Test Evaluation acc. Jenike
2 fc
i e
c Cohesion
E
Internal friction angle
Sha
er s
tres c
1Normal stress
Plastic deformation
i = internal friction angle
e = effective angle of internal friction
fc = uniaxial compressive strength
1 = major principal stress (axial)
2 = minor principal stress (radial)
14Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
S
N Past industrial standard
Sample size: 600 ml
Material requirement: 3 - 15 Liter
Max. travel <= 5mm
Suitable for materials with x95< 4 mm
Bulk Solid Properties: Jenike Shear Cell
N = normal force, S = shear force
15Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Bulk Solid Properties: Walker Ring Shear Cell
Walker Ring Shaer Tester
Sample size: 2 Liter
‚unlimited‘ travel
Several data points per sample
Suitable for products with x95< 4 mm
Probenbeheizung bis ca. 80°C
TI
N el. Beheizungu. Isolation
Deckel
S
Meßhebel (fest)
ProduktprobeRingzelleel. Beheizungu. Isolation
Antrieb
16Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Compaction Shear
52.55
Lower PistonLower Punch
SampleShear Plane
Ledge
46.63
41.48
Die
Outer Piston
Inside Piston52.40
44.32
23*
Bulk Solids Properties: Johanson Hang-Up Indicizer
17Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Flow Profiles and Flow Properties
Mass Flow Funnel Flow Arching Ratholing
Dead zone
Flow channel
18Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
1
1
Compaction with cohesive products
Jamming with coarse, non cohesive products
Types of Arching
19Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Cost of Method [£]
Prob
ability of S
uccess [%
]
Phon
e call, letter
Book, jou
rnal
Seminar, sho
rt visit
Feasibility stud
y
Shear test
Pilot p
lant te
sting
Full scale testing
0
20
40
60
80
100
0,1 1 10 100 1000 10000 100000
Quelle: H. Wright, bulk solids handling, 8(1988)5, 627-628
Process Engineering Silo Design
20Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Silo Pressure Profiles
Material element
D
H
h* 1= fckrit
dmin
1
1fc
1
Hydrostatic pressure of a liquid
fc, 1, 1
1 = major principal stress1 = embankment stressfc = uniaxial compressive
strength at 1
21Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Silo Stresses
wa. b. w
wc. wd.
a. Filling stateb. Beginning dischargec. Mass flowd. Funnel flow
Quelle: J. Schwedes, TU Braunschweig 1985
22Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Silo Design acc.to JenikeRepresentative sample
Operating Conditions
Wall material
Storage time
Storage temperaturehumidity
.
.
.
Silogeometry
Design for mass flow
or
Hopper angle
Silo shape
Storage volume
Mass flow angle
Sheartesting
Wall frictionµ = tan(x)
Bulk solids density
b
Friction anglee, i
Flow function, time flow function:fc ÷ 1
Hopper angle
Pressure distributionin hopper Critical stress conditions
Minimum outlet size against arching and ratholing
Jenike - Method(Bulletin 123)
23Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Silo Design: Mass Flow – Funnel Flow Boundaries
Axial-symmetric Silo Plane Silo
Quelle: DIN 1055, Beuth Verlag 2005
Funnel Flow FunnelFlow
Mass Flow possible
Mass Flow possible
DIN 1055: 2005
Hopper inclanation
Hop
per w
all f
rictio
n co
effic
ient
h
= ta
n x
Hopper inclanation
Hop
per w
all f
rictio
n co
effic
ient
h
= ta
n x
24Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Silo Design: Mass Flow – Funnel Flow Boundaries
DIN 1055: 1984
Quelle: DIN 1055, Teil 6; Beuth Verlag 1984
Axial-symmetric Silo Plane Silo
25Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Silo Desgin: Silo Shapes
Dmin
ax
D
H
ax eben
H
B
Bmin
eben
H
B
Bmin
L > 3 * Bmin
L
Axial-symmetric pyramidal plane
steep Less steepsteep
26Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
*STUDY BY TERBORG OF 500 SAMPLES
Mass Flow Angle*
100
80
60
40
20
00° 10° 20° 30° 40°
Hopper angle (axial-symmetric hopper)
% p
ropo
rtion
odf
hop
pers
with
mas
s flo
w
axc
c
27Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Flow Promotion – not this way
© BASF SE, 1999
Silo Design: Silo Discharge for Mass Flow
Flow properties
Storage time
Silo Shape
28Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Dmin/D
ax
15°
30°
0,5
4m
Rotary valve
Vibrating hopper
Scraper
Live Bottom
29Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Silo Design: Minimum Silo Outlet and Time consolidation
Mass Flow Silo
Maximum stoppage time: 3 days (week end)
Continuous discharge
Flow promoters
conveyor
Flow promoter, continuous
Flow promoter after prolonged stoppage
Alternative: Recycling
Dmin(3 d)
Dmin
DAus
Gravity flow
Flow promoters, short term
Discharge device
Conveyor
30Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Mechanical Conveying: Screw Conveyors
Principle:
Screw helix moves through the material
50 - 200 rpm
Operational conditions
L < 6 m, no intermediate bearing
L < 60 m , intermediate bearing
Horizontal, vertical,
tilted (<30°)
Several feed or discharge ports
Closed system (inert atmosphere)
No bends (exception: flexible screw conveyors)
Single and multiple screws
Additional features
Heating, cooling, mixing, homogenizing, degassing …
31Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Mechanical Conveying: Flexible Screw Conveyors
Screw without core (pig tail) rotates in a flexible casing (plastic hose)
Advantages Low investment cost Can manage one bend Horizontal or vertical
Disadvantage Low capacity (DN200: 40 m³/h) L < 15m; H < 12m High rotational speeds Wear of casing and helix
(Ermüdungsbruch) Incomplete discharge
32Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Mechanical Conveying: Vibratory Conveyors
Models Electromagnetical vibratory conveyors
– Non balanced mounting– L < 6m
Isolated counterbalanced vibratory conveyor
– Heavy (balancing weights)– L = 6 - 30 m possible– Q > 100 to/h
Products Suitable for: hot, abrasive, dusty Nor sited for: cohesive, tacky
Design Several feed and discharge ports horizontal up to ±5° No bends
33Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
MaterialClass
1 2 3 4 5
Powder sluggish100 –300mesh
Powdersluggishadhesive (incl. class 1 when damp)
Powder sluggishfluidizes3 – 325mesh
Granualrfree-flowing>100 mesh> 25 Ib/ft3
Fibrous, flaky, floccu-lent
Large particlesSizes> 3˝
Abrasive solids
High temp-era-ture
Belt conveyor
Vibratory conv
Drag chain c.Redler conv
Plastic elevator
Screw conv.Flex screw converyor
Drag disc conv. AeroMech
Bucket elevator
34Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Belt Conveyor
Drag chain conveyor
Drag disc conveyor
Screw conveyor
Vibratory conveyor
Aeromechanical conveyor
Flexible screw conveyor
Screw feeder without intermediate bearings
30 60Conveying distance [m] 100 150
Feed
er /
Con
veyo
r
35Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Pneumatic Conveying Principle
Discharge air
Pressureizedair
Product
PI
Ambient air Feed port
Silo with filter unit
36Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Geldard diagram of fluidization
10000
5000
2000
1000
500
200
10010 20 50 100 200 500 1000 2000 5000
Mean particle size dp [µm]
Den
sity
diff
ernc
e (
s– F
) [kg
\m
3 ]
Group C
Group AGroup B
Group DDiagram acc. to Geldart, boundaries acc. to Molerus
37Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Pneumatic Conveying StatesHorizontal Conveying
Dichtstromförderung Dünnstromförderung
DruckförderungstabilerVollrohr-/Kolben-
Saug- oder Druckförderung
Instabiler stabiler FörderbereichKolben- / Dünen- / FlugförderungDünen-
ruhendeSchüttung
Gutdurchsatz
log (mittlere Gasgeschwindigkeit)
Leerlaufkurve
log
(bez
ogen
er D
ruck
verlu
st/L
änge
nein
heit)
vmin v *
c)d)
f)
e)
pmin
b)
a)
MS3MS2MS1MS0= 0MS = 0.
MS3 > MS2 > MS1. . .
. . . .
Dichtstromförderung Dünnstromförderung
DruckförderungstabilerVollrohr-/Kolben-
Saug- oder Druckförderung
Instabiler stabiler FörderbereichKolben- / Dünen- / FlugförderungDünen-
ruhendeSchüttung
Gutdurchsatz
log (mittlere Gasgeschwindigkeit)
Leerlaufkurve
log
(bez
ogen
er D
ruck
verlu
st/L
änge
nein
heit)
vmin v *
c)d)
f)
e)
pmin
b)
a)
MS3MS2MS1MS0= 0MS = 0.
MS3 > MS2 > MS1. . .MS3 > MS2 > MS1. . .
. . . .
Dense Phase Conveying Lean Phase Conveyingpressure‐ or vacuum conveying
Stable plug flow Instableplug flow
Solids conveying rate
Air only
Granular bed at rest
(log) mean gas velocity, v
(log) re
lative pressure drop, p/l
Stable dispersion flow
3Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012
Pneumatic Conveying: Air flow controller
Dense phase conveyor (Roto-Conveyor or pressure vessel system)
Laval nozzle with variable nozzle geometry
Almost constant air flow rate (ideal pump characteristic) at all pressure levels up to the supply pressure
Suitable for explosion protection areas (no ignition sources)
Can supply systems with various discharge ports and conveying distances (routing and run length) Q [m³/h]
p
[mba
r]
VentilatorCompressorAir flow controller
Fa. Waeschle
Being an Engineer in IndustryThe phone call
4:30 pm a customer calls
A new factory for our product „Powdery White“
Can you design the handling and shipping facilities for us?
YES, ......
Oh, and we have two grades, the fine and the instant product.
What question do you ask?
Product Split, Production capacity
Product Data
Storage Volume, Storage Time
Packaging (bags, Super Sacks, loose)
What do you suggest to do?
…
…
…
39Dr. Hermann J. Feise, GOH/C Science Relations and Innovation Management24.09.2012