Air Cannons Improve Safety

An improved air-cannon configuration eliminates backflow and clogging at a cement plant. 

Heidelberg Cement’s Lehigh-Hanson facility in Leeds, AL, upgraded its materials-handling system to resolve accumulation issues in its clinker cooler. Where clinker discharged from the kiln and fell into the clinker cooler, chunky material would cling to the static cooler grates and/or cooler curbs. Air cannons are commonly used to remedy this, but if they experience clogging from backflow or if they’re set in an environment that is too hot to properly maintain them, accumulations inevitably form. “Our cannons were located close to cooler walls where the conditions were very hot and dusty,” said Mike Schutt, Production Manager. 

With a 24-hr. production schedule, 175 ton/hr. of raw material is passed through the kiln, reaching approximately 3,500 F. Accumulations formed at the discharge point, reaching as high as 20 ft. in as little as a single shift. The buildup could stretch back into the kiln and cause serious problems, resulting in excessive downtime and an increased operation cost.  

The company’s initial solution had five cannons with standard OEM piping leading directly to problem areas located near the hottest part of the cooler. The area had an average sustained temperature of 150 F to 165 F, which made maintenance during operation extremely difficult. Over time, fine particulates from discharged clinker would migrate up the air cannon discharge pipe. Clinker dust would also settle within the cannon tank, diminishing the tank’s capacity and decreasing the power and effectiveness of the shot. 

Workers donned hot suits and were required to remove the entire cannon from the manifold for valve service. Reported to have been one of the most unpleasant projects in the plant, at least two workers were needed to perform the maintenance and, due to the heat, were only able to remain in the area for 5 min. at a time. 

“The system broke down so often, we finally just had to leave it and monitor the material buildup until the very last minute, then shut down the system for maintenance,” Schutt said. “This allowed us to get the most production possible, but it caused at least a day of unscheduled downtime a few times per year.” 

Rethinking buildup

Working with Martin Engineering, Neponset, IL (martin-eng.com), using advanced air cannon technology and an innovative mounting strategy, five 150-liter Martin Hurricane air cannons were installed in a long U-shaped pipe configuration away from the hottest area of the cooler. The units deliver powerful material flow support with easy maintenance. 

Lifting the units away from the discharge area and up several meters to a preexisting platform located well away from the hot wall and the kiln’s discharge zone, the cannons can be serviced without having workers wear the special high-temperature equipment.

Connected to the existing compressed-air system, the cannons supply more force output with less air consumption at half the size of other designs. Each unit fires a shot of air to 120 psi (8.27 BAR) from a pressurized tank through the long pipes and spreads the airstream across the area of buildup.  

To prevent unintentional firing due to drops in pressure, the valve requires a positive signal from the solenoid in the form of an air pulse. Able to be located as much as 200 ft. away from the cannons, the solenoid panel also allows operators to fire manually if needed. The Hurricane’s valve faces outward, opposite the pipe end, and is serviced without removing the cannon tank. A single technician simply detaches the air and solenoid connections, removes the eight bolts from the valve assembly, and slides it out for inspection and maintenance.

Moving forward

“After five years of constant operation, the results have been better than we ever expected,” reported Schutt. “Since the installation, we have had a significant reduction in downtime due to accumulation.”

The lack of heat exposure has reduced the impact on the equipment itself, increasing the life of the valves and the tank. Setting the tanks in an easily accessible and safe area means that workers can inspect the equipment more often and perform maintenance on a single cannon without downtime.

The cannons no longer experience buildup from backflow within the tank, allowing them to operate at full capacity. “Overall, we are very satisfied with the design and the equipment,” Schutt concluded. “I can see this configuration becoming a standard design across the cement industry.” The result is a safer workplace, extended equipment life, less downtime, and a lower cost of operation. EP

For more information, visit martin-eng.com.