Handbook of Mechanical Engineering Calculations ar Episode 1 Part 10 doc

10.1

SECTION 10

MATERIALS HANDLING

Choosing Conveyors and Elevators for

Specific Materials Transported 10.1

Determining Equipment Design

Parameters for Overhead Conveyors

10.4

Bulk Material Elevator and Conveyor

Selection 10.9

Screw Conveyor Power Input and

Capacity 10.13

Design and Layout of Pneumatic

Conveying Systems 10.15

CHOOSING CONVEYORS AND ELEVATORS FOR

SPECIFIC MATERIALS TRANSPORTED

Determine the maximum allowable product weight between supports that can be

handled by a belt conveyor at any one time when it conveys 100,000 lb/ h (4540

kg/ h) of pulverized aluminum oxide in an abrasive state at a belt speed of 50 ft/

min (15.2 m/min) with a center-to-center distance of 32 ft (9.75 m) between belt

supports. Compare this capacity with that at belt speeds of 150, 250, and 350 fpm

(45.7, 76.2, and 106.7 m/min). Choose the type of conveyor and elevator to handle

this material under the conditions given.

Calculation Procedure:

1. Find the maximum allowable product weight at the given belt speed

Use the relation, P
KC/ 60 S, where P
maximum product weight on the belt

at any one time, lb (kg) between belt supports; K
load, lb/ h (kg/ h); C
center￾to-center distance between belt supports, ft (m); S
belt speed, ft/min (m/min).

Substituting, we have, P
(100,000)(32)/ 50 (60)
1066.7 lb (484.3 kg).

2. Determine the maximum allowable product weight at other belt speeds

Typical conveyor belt speeds vary from a low of 150 ft/min (45.7 m/min) to a

high 800 ft/min (243.8 m/min), depending on belt width, type of material con￾veyed, belt construction, etc.

For this belt, using the data given earlier, P
(100,000)(32)/ 150(60)
355.6

lb (161.4 kg) when the speed is 150 ft/min (45.7 m/min). Likewise for the two

higher speeds, respectively, P
(100,000)(32)/ 250(60)
213.3 lb (96.9 kg); P

(100,000)(32)/ (350(60)
152.4 lb (69.2 kg).

3. Verify the type of conveyor and elevator to use

With such a wide variety of conveyors and elevators to choose from, it is wise to

verify the choice before a final decision is made. Table 1, presented by Harold V.

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Source: HANDBOOK OF MECHANICAL ENGINEERING CALCULATIONS

10.2

TABLE 1 Preferred Types of Conveyors and Elevators for Bulk and Packaged Materials

Material

Physical

condition

Av wt/ volume

lb/ ft3 kg/ m3

Reaction on

conveyor

Preferred

conveyors*

Preferred

elevators* Comment

Acid phosphate

Alum

Aluminum oxide

Ammonium nitrate

Ammonium nitrate

Arsenic salts

Ashes: dry

wet

Bone meal

Borax

Bran

Brewers grains, hot

Carbon black (pellets)

Cement, dry

Clays

Coal: anthracite

steam sizes

bituminous, lump

bituminous, slack

Chalk

Coffee beans

Copra, ground

Cork, ground

Corn, shelled

Cottonseed

Cullet

Flaxseed

Flue dirt

Fly ash, clean

Glass batch

Glue

Graphite (flour)

Gravel

Gypsum

Heavy ores

Hog fuel

Lead salts

Lime, pebble

Damp

Granular

Pulv.

Pulv.

Damp

Pulv.

Granular

Sticky

Pulv.

Pulv.

Granular

Granular

Granular

Pulv.

Pulv.

Lumpy

Granular

Lumpy

Granular

Pulv.

Granular

Pulv.

Pulv.

Granular

Granular

Granular

Granular

Pulv.

Pulv.

Granular

Granular

Pulv.

Granular

Pulv.

Lumpy

Stringy

Pulv.

Granular

90

60–65

60

62

65

100

35–40

45–50

55–60

50–70

16–20

55

40

90–118

35–60

50–54

50–60

50–60

50–60

70–75

40–45

40

5–15

45

35–40

80–100

45

100

35–45

80

45

40

95–135

60

100

15–30

60–150

55–80

1,440

960–1,040

960

990

1,040

1,600

560–640

720–800

880–960

800–1,120

260–320

880

640

1,440–1,890

560–960

800–860

800–960

800–960

800–960

1,120–1,200

640–720

640

80–240

720

560–640

1,280–1,600

720

1,600

560–720

1,280

720

640

1,520–2,160

960

1600

240–480

960–2,400

880–1,280

Adheres

Abrasive

Abrasive

Hygroscopic

Adheres

Heavy

Abrasive

Abrasive

Abrasive

Corrosive

Adheres

May be abra￾sive

Abrasive shell

Sometimes

sticky

Abrasive

Shell abrasive

Abrasive

Mild abrasive

Abrasive

Lubricant

Abrasive

May jam

a, e

a, b, c, e

a, e

b, c, e

c, e

c, e

d, f

f

a, b, c, d, e

a, b, c, d, e

a, b, c, d, e

c, e

a, e

a, c, d, e

a, b, c, e

a, b, c, e

a, b, c, d, e

a, b, e

a, b, c, d, e

a, b, c, d, e

a, c, e

a, b, c, e

a, b, c, d, e

a, c, e

a, b, c, d, e

a, b, e

a, b, c, d, e

b, d, e, f

a, b, c, d, e

a, b, e

a, c, e

a, b, c, d, e

a, e, f

a, b, c, e

a, b, f

a, b, d, e

a, b, c, e

a, b, c, e

b

g, b

g

g, b

g, b

g, b

b

b

g, b, c

g, b

g, b

g, b

g, b

g, b

g, b

g, b

g, b, c

b

g, b, c

g, b, c

g, b

g, b

g, b

g, b, c

g, b

g, b

g, b, c

g, b

g, b, c

g, b

g, b, c

g, b, c

g, b

g, b

g, b

g

Sticky

Explosive

Sticky

Poisonous

Dusty

Corrosive

Sometimes sticky

Fragile

Packs

Sluggish

Sluggish

Fragile

Sticky

Sluggish

Corrosive

Free-flowing

Free-flowing

Keep cool

May be tough

Poisonous

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MATERIALS HANDLING