MATERIALS HANDLING
Using proven fl ow technology
like a vibrating dribble chute and air cannons working in tandem will promote more uptime and greater production
Hinged drip pans designed to be lowered with winches
surface. A vibrating dribble chute is a vibrator attached to a fl oating low friction liner to make the surface active using vibration and gravity to move the material toward the discharge stream. In some cases, whole chutes can be isolated to make the applied vibration more eff ective.
AIR CANNONS FOR TRANSFER CHUTES Air cannons have demonstrated to be highly eff ective for aiding fl ow and eliminating clogging of diff icult materials in large chutes. The benefi t of air cannons is that, when properly mounted, they dislodge material in typical buildup prone areas such as corners and low angle surfaces. Air cannons release pulses of compressed air to shear buildup from surfaces. They are simple devices with one moving part that only requires compressed air and a trigger method. The cannons can be discharged manually as needed or on a timed sequence. The cannons are pointed in the
direction of the cargo fl ow providing 48
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consistent and eff icient production. Firing sequences are accomplished with a simple timer set at an interval based on the cycles of material fl ow. Intervals can be fi ne-tuned for fl uctuations in humidity or freezing where clogging is more prevalent, or during changes in volume, material type or belt speed, when added fl ow aids are required. Adjustments to fi ring sequences are accomplished manually by a nearby solenoid box or can be routed to a centralized logistical system. Another use of air cannons on
dribble chutes is to angle the nozzle downward behind a heavy fl exible curtain that ripples when the air cannon is fi red, dislodging the adhered material from the surface. Ideally, the curtain would be made from a rubber material with a slick low-friction face that is easily replaceable once it is worn.
IN SUMMARY Problems associated with carryback – such as cleaning spillage, clearing
buildups and unclogging chutes – used to be considered a cost of doing business. For operators experiencing excessive buildup from carryback, labour costs and workplace safety concerns might require a review of the discharge zone design of their belt conveyors. Over time, when calculating for labour and lost production, unplanned outages to manually clean spillage can justify the cost of a total discharge zone redesign. This includes a larger head pulley, the adequate number of cleaners for the application, and a complete transfer chute confi guration with fl ow aids. Using proven fl ow technology like a vibrating dribble chute and air cannons working in tandem will promote more uptime and greater production.
R. Todd Swinderman is President Emeritus, Martin Engineering.
www.martin-eng.com
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