Aug 10

Design of Screw Conveyor:

01-screw conveyor-screw conveyor design-screw conveyor design calculations-screw conveyor housing- screw conveyor flights- screw conveyor formulae- screw conveyor flow rates

The size of screw conveyor depends on two factors

1. The capacity of the conveyor

2. The lump size of the material to be conveyed (Maximum dimensions of the particle)

Usually there are three ranges of lump sizes which are considered for selection of screw size. These are:

· A mixture of lumps and fines in which not more than 10% are lumps ranging from maximum size to one half of the maximum, and 90% are lumps smaller than one half of the maximum size.

· A mixture of lump and fines in which not more than 25% are lumps ranging from the maximum size to one half of the maximum, and 75% are lumps smaller than one half of the maximum size.

· A mixture of lump only in which 95% or more are lumps ranging from maximum size to one half of the maximum size and 5% or less are lumps less than one tenth of the maximum size.

The allowable size of a lump in a screw conveyor is a function of the radial clearance between the outside diameter of the central pipe and the radius of the inside of the screw trough, as well as the proportion of the lumps in the mixture.

The lump size of the material affects the selection of screw diameter which should be at least 12 times larger than the lump size of a sized material and four times larger than the largest lumps of an un-sized material.

Example, if screw diameter is 250mm means radial clearance is 105mm, & Maximum lump size is 60mm of 10% lumps.

Capacity of Screw Conveyor:

01-screw conveyor capacity calculation-screw conveyor manufacturers-screw conveyor shaft- screw conveyor capacity- screw conveyor components- screw conveyor bearings

The capacity of a screw conveyor depends on the screw diameter, screw pitch, speed of the screw and the loading efficiency of the cross sectional area of the screw. The capacity of a screw conveyor with a continuous screw:

Q = V. ρ

Q = 60. (π/4).D2.S.n.ψ.ρ.C

Where,

Q = capacity of a screw conveyor

V = Volumetric capacity in m3/Hr

ρ = Bulk density of the material, kg/m3

D = Nominal diameter of Screw in m

S = Screw pitch in m

N = RPM of screw

Ψ = Loading efficiency of the screw

C = Factor to take into account the inclination of the conveyor

Screw Pitch:

Commonly the screw pitch is taken equal to the diameter of the screw D. However it may range 0.75 – 1.0 times the diameter of the screw.

01-screw conveyor pitch- screw conveyor inlet- screw conveyor output- screw conveyor blade- screw conveyor motor

Screw Diameter:

Nominal Size D

Trough height from center of screw shaft to upper edge of the trough

Trough width C

Thickness of Tough

Tubular shaft (d1 * Thickness)

Outside diameter of solid shaft

Coupling diameter of shaft

Heavy Duty

Medium Duty

Light Duty

100

63

120

-

2

1.6

33.7*2.5

30

25

125

75

145

-

2

1.6

33.7*2.5

30

25

160

90

180

5

3.15

1.6

42.4*2.5

35

40

200

112

220

5

3.15

2

48.3*3.5

40

40

250

140

270

5

3.15

2

60.3*4

50

50

315

180

335

5

3.15

-

76.1*5

60

50

400

224

420

5

3.15

-

76.1*5

60

75

500

280

530

5

3.15

-

88.9*5

70

75

RPM of Screw:

The usual range of RPM of screw is 10 to 165. It depends on the diameter of screw and the type of material (Max RPM of screw conveyor is 165)

Loading efficiency:

The value of loading efficiency should be taken large for materials which are free flowing and non abrasive, while for materials which are not free flowing and or abrasive in nature, the value should be taken low:

Ψ = 0.12 to 0.15 for abrasive material

= 0.25 to 0.3 for mildly abrasive material

= 0.4 to 0.45 for non abrasive free flowing materials

Inclination Factor:

The inclination factor C is determined by the angle of screw conveyor with the horizontal.

 

Angle of screw with the horizontal

10°

15°

20°

Value of factor C

1

0.9

0.8

0.7

0.65

You might also like

Screw Conveyor Power Calculation | Screw Conveyor Capacity Calculation | Screw Conveyor Formulae
Power requirement of Screw Conveyors: The driving power of the loaded screw conveyor is given by:...

Screw Conveyors | Screw Conveyor Working Principle | Screw Conveyor Systems
Screw Conveyors Screw conveyors were used as low height lift pump to irrigate the lands. It comprises...

Vertical Screw Conveyors | Vertical Screw Pump | Vertical Screw Conveyor Design
Vertical screw conveyors: A vertical screw conveyor conveys material upward in a vertical path....

Screw Conveyor Working | Screw Conveyor Applications | Screw Conveyor Pdf
Application of screw conveyors: Screw conveyors are employed for handling a great variety of materials...

.

Comments are closed.

preload preload preload