An essential part of the cement production process is the consistent flow of bulk materials, as poor material flow can put a stranglehold on a plant’s profitability. Accumulations in storage systems and process vessels can choke material movement, causing bottlenecks that create expensive obstacles to equipment performance and process efficiency.
Poor material flow also raises maintenance expenses, diverting manpower from core activities. If they become severe enough, flow problems can bring production to a complete stop.
Air cannons have a long history of resolving material flow issues associated with bulk handling. Also known as 'air blasters,' they are employed in a number of applications in cement production, from unclogging hoppers to moving super-heated material through the cooling process. Recent innovations in the engineering, installation, assembly, and design of air cannons have been particularly effective in maintaining safe, efficient flow in preheater towers.
"As raw materials travel through the conveying, crushing, calcining, mixing, and packaging processes, air cannons are instrumental in maintaining process flow," explained Sid Dev, Martin Engineering Product Manager for air cannons. "They function by releasing a powerful shot of pressurised air from a tank through a pipe assembly to a specialised nozzle, removing collected material from surfaces and directing it back into the process stream."
Early technologies
Early air cannon designs exposed several issues, including compressed air consumption, safety, and the downtime associated with installation and maintenance. Until recently, cannons relied on air tanks that often weighed hundreds of pounds, with inward-facing valves firing straight across the vessel. To perform maintenance on the valve, the whole tank required removal, involving significant labour and time, and posing potential safety issues due to the weight of the units.
Some equipment created a significant drain on other systems sharing the compressed air system, raising the cost of operation. Older models featured negative firing valves that had the potential to misfire due to drops in pressure, throwing off the firing sequence and further burdening the compressed air system.
Modern air cannon design
"The last decade has seen a revolution of sorts in air cannon technology," said Dev. "Engineers have gone back to the drawing board and completely reinvented the equipment from the moment air enters the tank to its contact with material. It has become more efficient, cost-effective, and safer to service."
Today, design and engineering advancements are producing air cannons that are more compact and lighter, with greater efficiency and power. Suppliers are innovating the way they’re built, installed, serviced, and powered in order to maximise production and reduce both downtime and the overall cost of operation, while contributing to improved safety.
To extend service life, high heat retractable nozzles are now available for especially abrasive locations, extending into the vessel to fire, then retracting back into the protective pipe. Both the rugged construction and reduced exposure to punishing environments extend nozzle life. They are also designed to be easily removed from a flange by a single worker and serviced as individual units outside of a Y-pipe assembly, without shutting down production.
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