MATERIALS HANDLING
air to deliver an abrupt discharge to dislodge the buildup. Te basic components include an air reservoir, fast-acting valve with trigger mechanism and a nozzle to distribute the air in the desired pattern to most effectively clear the accumulation. Te device performs work when
compressed air (or some other inert gas) in the tank is suddenly released by the valve and directed through an engineered nozzle, which is strategically positioned in the chute, tower, duct, cyclone or other location. Often installed in a series and precisely sequenced for maximum effect, the network can be timed to best suit individual process conditions or material characteristics. To customise the air cannon installation
to the service environment, specific air blast characteristics can be achieved by manipulating the operating pressure, tank volume, valve design and nozzle shape. A new process has been developed for installing air cannons in high-temperature applications without a processing shutdown, allowing specially trained technicians to mount the units on furnaces, preheaters, clinker coolers and in other high-temperature locations while production continues uninterrupted. Te new technology is designed to dramatically reduce expensive downtime associated with traditional installation methods, which require that high-heat processes be halted to allow core drilling and mounting of the cannons. Tis new approach allows technicians to add air cannons and nozzles to an operation while it’s in full swing, without disrupting the process. It’s been proven in dozens of installations to date, helping high-temperature processes maintain effective material flow and minimise shutdowns, improving efficiency while reducing lost production time.
ENGINEERED VIBRATION
Te age-old solution for breaking loose blockages and removing accumulations from chutes and storage vessels was to pound the outside of the walls with a hammer or other heavy object. A better solution is the application of engineered vibration, which supplies energy precisely where needed to reduce friction and break up the material to keep it moving to the discharge opening, without damaging the chute or vessel. Vibrators reduce the cohesion between the material particles and the adhesion between the particles and the container wall to increase the material flow. Te devices activate the material inside a chute or bin by energising the outside of the structure’s steel walls and transmitting vibratory waves into the bulk solid. Linear vibration is the best solution
for sticky, coarse, high-moisture materials. A convenient test is to take a handful of material and squeeze it into a ball. If the material readily remains in the ball after the fist is opened, linear vibration is probably the best choice. In contrast to linear designs, rotary vibrators create a vibratory force through the rotation of an eccentric weight, which creates a powerful vibration much as a household washing machine does when its load is off-centre. Tey supply an energy best suited to moving fine, dry materials.
New technology allows air cannons
to be installed and serviced without a process shutdown
Vibration can induce stress into metal
structures, and the walls may need to be reinforced at the point(s) of application. Vibrators are typically installed on a mounting plate or channel that spreads the vibratory energy (and the weight of the device) over a larger surface area. Because flow-aid devices often use
compressed air or other energy sources that can create a stored energy hazard, it is critical to follow lockout/tagout/ blockout/testout procedures. Even though build-up in a chute may still be in place, its hold on the chute wall might be weakened to the point that a slight disturbance during maintenance can cause it to fall. Tere is also an electrical shock hazard when working on the control systems. To prevent the possibility of remotely energising devices during maintenance and testing, appropriate safety procedures must be in place to prevent unintended actuation.
A series of air cannons can be programmed to deliver precisely timed operation for maximum benefit
Air cannons deliver a precisely controlled burst of compressed air to dislodge material buildup
Brad Pronschinske is with Martin Engineering.
www.martin-eng.com
www.engineerlive.com 47
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