1.1 Belt conveyor

1.2 Apron belt conveyor

1.3 Belt balance for dosing

4.1 Screw feeder

4.2 Rotary feeder, star feeder

4.3 Rotary scraper

4.4 Table, Disk, Roller feeder

4.5 Agitator, Stirrer

4.6 Rotary plough, arms, beams

2.1 Sceleton flight conveyor

2.2 Chain feeder

Hopper Discharge Devices

with traction without traction

1. Belt feeder 2. Chain conveyor 3. Vibratory 4. Rotary 5. Other as feeder: feeder: feeder: devices:

3.1 Pushed chute

3.2 Discharge chute

3.3 Dosing chute, pipe

3.4 Vibratory bin

3.5 Dosing screen, beams, perforated bottom

3.6 Pendular bottom (walking floor)

5.1 Hopper outlet valves, gates

Arrangement of Bin-Feeder Interface for Mass Flow

1. Flange arrangement of bin-feeder transition 2. Double plates a) wrong b) right a) wrong b) right

3. a) gate with horizontal obstacle b) partially opened plate within the outlet area rotary valve

4. Discharge of easy flowing powder by rotary feeder

5. Arrangement of rotary plough feeder a) plough b) outer c) under- too short wall step scratching

dead zoens

chute interface

outlet cross section offeeder plate

closedsaddle

stagnant zone

plateopened

chutefitting turned to right

dead zone

deadzonesin theedges

free cross section

dead zone

deadzone

deadzone

no powderdischarge

stagnant zone

rotary plough

6. Draw-off behaviour of belt conveyor

a) in front at smooth belt and large b) uniform at sloping striker plate vertical gate opening, (increasing draw-off height) back at rough belt and small vertical gate opening

c) uniform at widen chute opening d) uniform at increasing weir level (sloping cross-sectional area of outlet) (sloping draw-off height)

7. Boundary (interface, shear zone) of horizontally drawn-off powder layer

8. Sceleton flight conveyor with sloping plates within chute interface

sloping plates, skirts or liners

trough,skeleton flight conveyor

direction ofconveying

aus: Schulze, D., Austragorgane und Austraghilfen, Chem.-Ing.-Techn. 65 (1993) 48-57

hopper outlet levelb) uniform powder draw-off

c) only in front draw-off

a) draw-off from back

gate or weir level andbulk heighton belt hB

Arrangement of Bin-Feeder Interface for Mass Flow

weir plates

Feeders for Powder Discharge of Mass Flow Bunker1. Belt and sceleton flight (Redler) conveyorfor mass flow

3. Rotary feeder for mass flow

bmin

. .... . ... .

.

.. .. . . .. .. . . .. . ... . .......

B

chute interfacewith guide skirt

. . .... . . ..... . ....

lminh R

2

2 1

b min

b R

1lmin/hR = 1 - 1,5

BB

b min

...

. ... .. ... . .. . ..

.. .

........

. ..

.

...

.

.

.. .. . . ...

..

.. . .

.

.

....

.. .

... .... .

..

..

..

.. .. .. . .

1

2 h Bb A

. ...

. .

. ..

.

...

.

lmin

b B

sloping strikerplate

widen discharge opening

bmin

h S

2. Vibratory chute for mass flow

a) wrong b) right

a) wrong b) right

a) wrongb) right

2 = 1 - (5 - 8°)

1 = 3 - 5°

1 = 2 = 3 - 5°

double rotor

hS = (1 - 1,5).b

4. Screw feeder for mass flow at wedge-shaped hopper

I) wrong II) right

Feeders for Powder Discharge of Mass Flow Hopper

constant pitchuniform draw by variable pitch

a) progressive pitch sS

b) progressive screw diameter dS c) degressive core diameter dK ( = 5°)

d) degressive screw wall thickness bS

e) progressive paddle pitch f) right- and left-hand screw with centric or periphere discharge

dead zone

5. Vibratory bin for mass flow ("Bin Activator")

Feeders for Powder Discharge of Mass Flow Bunker

Vibratory Bin

600 900 1200 1500 1800 2100 2400

module size (bin outlet diameter) D in mm

1,5

1,0

0,5

0

inst

alle

d po

wer

con

sum

ptio

n P

in k

W

4

3

2

1

0

spec

ific

pow

er c

onsu

mpt

ion

P/m

in W

/kg

1100

1000

900

800

700

600

500

400

300

200

100

0

mas

s m

in k

g

20

15

10

5

0

reco

mm

ende

d pr

ice

K in

TD

M

80

70

60

50

40

30

20

0

10

spec

ific

pri

ce K

/m in

DM

/kg

m

K

P

P/m

K/m

1. Vertical stress v and tangential (horizontal) draw-off force Fh on a) Rubber belt conveyor without guide skirt b) Apron belt conveyor with guide skirt

c) Sceleton flight conveyor (Redler)

2. Time dependent filling height HFill, vertical stress v and horizontal force Fh

3. Vertical stress vG as function of displacement of discharge device z at filling

Tangential Force of Discharge Devices

HFüll HFüll

filling discharge

time

Fh v,0 .l.b.[tan( e) + 2.≈

Fh v,0 .l.b.[tan( e) + ≈

Fh = v,0 .l.b. tan( e)

posit

ion

of a

ctiv

e sh

ear

plan

e

Active and Passive Rankine's Stress State Limits

Yield locus: = tan i · + c = tan i ·( + Z) or R = sin i ·( M + Z)

ph,a

activepassive

shea

r st

ress

tensile strength Z

cohesion c

i

2,aa=

i4 2+

iR ,a

2· a

pv

1,a

yield locus

ph,p

1,p

p = i

4 -

2

M,p =1,p + 2,p

2

position of passive shear plane

R,p=1,p 2,p

2

-

active passive

principal stresses

lateral orhorizontal stress ratio

2,a = · 1+ · c

1 - sin i

1 + sin i

2 · cos i

1 + sin i1,p = · 2,p+ · c

1 + sin i

1 - sin i

2 · cos i

1 - sin i

lower limit for c = 0 upper limit for c = 0

ph,p

pv

= = = tan21 + sin i

1 - sin i(

4 + i

2p

ph,a

pv

= = = tan21 - sin i

1 + sin i

(4

- i

2a

·

·

·

active

i

4 2+

pv

ph,apv

ph,p

passive

i

4 2-

pv

ph,a

pvph,p

normal stress

given: pv = 1 = b.g y c,

searched: 2 stress states which meet the yield condition

y

x

2,p

unload peak at bridging

steady-state flow

Fillingpv = f(filling height H(t))

time t

vert

ical

load

Fv =

p v d

A

1

b

Fillingactive - plastic stress state

Dischargepassive - plastic stress state

Vertical Pressure upon a Discharge Device

Dischargepv = f(H) pv = f(b)

2

2

1

funnel flow zonepassive stress field

stagnant zoneactive stress field