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

2 Dr. C. L. Jones Biosystems and Ag. Engineering Materials Handling Assignment: –Read Chapter 8 handout

3 Dr. C. L. Jones Biosystems and Ag. Engineering Materials Handling More on Screw-type Conveyors xibleScrewConveyors/index.asphttp:// xibleScrewConveyors/index.asp himedes/Screw/Applications.htmlhttp:// himedes/Screw/Applications.html

4 Dr. C. L. Jones Biosystems and Ag. Engineering 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

5 Dr. C. L. Jones Biosystems and Ag. Engineering Materials Handling Bucket Conveyors –

6 Dr. C. L. Jones Biosystems and Ag. Engineering 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

7 Dr. C. L. Jones Biosystems and Ag. Engineering 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 info.html#ANIMATED%20.GIF%20Fileshttp:// info.html#ANIMATED%20.GIF%20Files

8 Dr. C. L. Jones Biosystems and Ag. Engineering 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

9 Dr. C. L. Jones Biosystems and Ag. Engineering 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)

10 Dr. C. L. Jones Biosystems and Ag. Engineering 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…

11 Dr. C. L. Jones Biosystems and Ag. Engineering 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

12 Dr. C. L. Jones Biosystems and Ag. Engineering 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

13 Dr. C. L. Jones Biosystems and Ag. Engineering 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!!!

14 Dr. C. L. Jones Biosystems and Ag. Engineering 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

15 Dr. C. L. Jones Biosystems and Ag. Engineering Materials Handling Cranes/Hoists Used in construction, generally Unloading barges Machine and assembly shops to move parts and units

16 Dr. C. L. Jones Biosystems and Ag. Engineering 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