Friday, April 18, 2008

Chemical Engineering Rules of thumbs – Conveyers [Screw, Belt , Bucket , Drag Type, Pneumatic]

Screw Conveyers

Screw Conveyers are suitable for sticky and abrasive solids with up inclined angle up to 200. Screw Conveyers. The conveying distance is normally up to 150 ft. A 12 in. diameter screw conveyer can transport solids at a rate of 1000-3000 cuft/hr with 40-60 rpm speed.

Belt Conveyers

Belt Conveyers are suitable for high capacity and long distance such as one or more miles with up inclined angle up to 300 . As example a 24 in. wide belt can use to convey material at 3000 cuft/hr with speed of 100 ft/min. Belt conveyers use low power when comparing to others.

Bucket Conveyers (Elevators)

Bucket Conveyers are suitable for vertical transport of sticky and abrasive materials. As example with 20 X 20 in. bucket, 1000 cuft/hr rate can be achieved at a rate of 100 ft/min.

Drag Type Conveyers (Redler)

Drag Type Conveyers are suitable for short distance transport in any direction and it is completely enclosed conveying method. Unit sizes are change from 3 in. square to 19 in. square and speed can be vary from 30 ft/min to 250 ft/min. Power requirements are comparatively high.

Pneumatic Conveyers

Pneumatic Conveyers are suitable for high capacity and short distance. Vacuum or low pressure is employed (6-12 psig) with 35 – 120 ft/sec range of air velocities depending on material and pressure.

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