1 Dr. C. L. Jones Biosystems and Ag. Engineering Topics in Processing Materials Handling

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Dr. C. L. JonesBiosystems and Ag. Engineering

Topics in Processing

Materials Handling

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Materials Handling

• Assignment: – Read Chapter 8 handout

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Materials Handling

• More on Screw-type Conveyors

• http://www.flexicon.com/us/Products/FlexibleScrewConveyors/index.asp

• http://www.mcs.drexel.edu/~crorres/Archimedes/Screw/Applications.html

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Materials Handling

• More on Screw-type Conveyors

• Example: determining capacity and HP– Screw-type conveyor, 14 in. screw dia.,

conveying soy beans, 300 rpm, 25 ft. length

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Materials Handling• Bucket Conveyors

– http://www.goughecon.com/

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Materials Handling

• More on Bucket Conveyors

• Example: determining capacity and HP– Bucket conveyor with buckets like Fig.

8.10(b)– Bucket is 10.5 in. long, curve radius = 7 in.– Spacing is 3x projected width– Lift is 125 ft., belt speed = 300 ft/min,

handling wheat

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Materials Handling• Oscillating conveyors (fig. 8.11)• Trough imparts velocities in x and y directions• Used often for metering components in mixing• Rate of movement is easy to change and

remains constant over long periods of time.• Hard to calculate performance…usually

established by testing …vendor will provide data from their testing labs

• http://www.goldequipment.com/gold-mining-equipment-info.html#ANIMATED%20.GIF%20Files

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Materials Handling

• Pneumatic conveyors (Fig. 8.13)• Moves granular material through a duct using

high-velocity stream of air.• Advantages:

– Low initial cost– Mechanical simplicity…1 moving part (fan)– Conveying path can be random and branched– Path can be changed easily– Can handle wide variety of materials– Self cleaning

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Materials Handling

• Pneumatic conveyors (Fig. 8.13)• Disadvantages

– High power requirement– Possible damage to conveyed materials

• 4 types of systems (fig. 8.14)– Suction: operates below atm. pressure– Low pressure: high vel. low density air (centrif. fan

<14in. water pressure)– High pressure: low vel. high density air (pos.

displacement blower)

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Materials Handling

• Pneumatic conveyors (Fig. 8.13)– Fluidized system: high press. air and high

density air (material in air like an air-material slurry) Low conveying velocities

• Suction system best for – unloading matls. where point of unloading

may move (trucks, freight cars, boats)– Matls. with texture that would not pass

easily through valves, screw conveyors…

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Materials Handling

• Pneumatic conveyors (Fig. 8.13)• Pressure system best

– Where point of discharge varies– Loading trucks, freight cars, barges

• Vertical movement (lift) usually 50 ft/sec. granular lift rate– So air rate=50 ft/sec + rate to support material– Usually 15 – 50 ft^3/lb of material– Table 8.5

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Materials Handling

• Pneumatic conveyors (Fig. 8.13)

• Static air pressure =– wall-air friction loss + – pressure from weight of matl. +– energy loss from matl. rubbing pipe

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Materials Handling• Pneumatic conveyors (Fig. 8.13)• Horizontal movement• Losses from friction of air on walls, grain on

air, grain on walls, and grain on grain• Disagreement on whether air rates are lower

or higher than vertical movement!!!• http://www.vigan.com/code/EN/gene.asp

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Materials Handling

• Gravity Conveyors

• Simple

• Series of rollers or wheels

• Level or very slight incline

• Handles boxes generally

• Moves by gravity or by hand if level

• Good for intermittent service

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Materials Handling

• Cranes/Hoists

• Used in construction, generally

• Unloading barges

• Machine and assembly shops to move parts and units

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Materials Handling• Trucks and Carts• Widely used in manufacturing and

warehouses• Forklifts• Dollies• Can fill in where a permanent conveyor

system isn’t practical• Intermittent flow rate processes

Documents

1 Dr. C. L. Jones Biosystems and Ag. Engineering Topics in Processing Materials Handling