How air cannons revolutionised cleaning at a cement plant
Recently, a cement plant in the Caribbean was experiencing issues in its raw material chute. Build-up occurred in the entire chute, but the principal problem was near the top. Sticky material fell into the chute in large chunks, blocking the chute.
The plant had installed air cannons supplied by three different vendors to fight this problem. Unfortunately, the air cannons were unable to shift the build-up, requiring manual clean-up. The plant was often forced to stop production and clean this chute every five hours. An average of 900 tons of production was lost per day, equating to a US$54,000 daily loss.
Jeff Shelton, IGS air cannon expert, says that: “Little has changed in the air cannon market over the past two decades, in terms of design of the cannon and its components. All the while, the cement industry has continued to innovate, creating new maintenance challenges. It was time that the air cannon technology caught up with the industry.”
Evaluating air cannon alternatives
The plant was made aware of the IGS Big Blue air cannons, which are widespread in the power industry, yet relatively new to cement. IGS has performed several improvements to the conventional air cannon component designs and cleaning power.
Chris Landers from IGS explains that, “For air cannons to solve build-up issues they must be applied correctly. The air cannons in this application were not applied correctly in our opinion. We felt there were issues with the following; location of nozzle, type of nozzle and the cleaning energy provided by each cannon.”
The effectiveness of a blast from an air cannon is determined by many factors. Location, orientation and type of nozzle applied to the cannon are instrumental in the success of an air cannon installation. But the type of blast from the cannon is also important.
There are two main types of air cannon blasts or discharges: a pusher, and a blaster. Both are effective in the correct application, but the key to success is applying the correct blast style to the type of material being moved and the desired results.
Air cannon companies have long touted the superiority of their cannons based on “peak force”. This is the initial power of the blast of the air cannon. The theory has ‘been more power means more material moved’. This has led companies to move to high peak force cannons but much smaller volumes of air applied. A high peak force is beneficial when the material to be blasted is very hard. The blast can break and shatter the hard material causing it to crumble and be blasted away. The blaster cannon does not work well with all materials though. The high peak force will penetrate completely through many materials only leaving a hole and not removing any build-up.
A pusher type cannon blast literally shoves the material out of the way. This can often be accomplished with a lower peak force, but using a larger volume of air with each blast. As long as the blast force exceeds the cohesive force bonding the build-up together or to the surface, the blast will remove the build-up. In addition, the blast time is longer, allowing it to penetrate further. The larger volume of air delivers more mass, creating more energy to affect the material.
Traditional air cannons from all manufacturers consist of a single air receiver tank with a firing/piston assembly to control the blast of compressed air. The firing assembly may be externally attached to the tank, or more recently, internal to the tank. Either way, the air cannon has always been mounted to a nozzle or pipe that had been installed in the location where material build-up needed to be removed.
Traditional air cannons needing to be mounted directly to the blast nozzle have always presented problems for the plant. The air cannon is mounted very close to the process resulting in extreme heat and material from the process impacting the cannon. These are the major contributors to any company’s air cannons failing.
Mounting the cannon this close to extreme heat makes it very difficult, if even possible, to perform any maintenance duties to keep the cannon operating. And the nozzles and cannons are often mounted very high on a silo or structure. Performing maintenance on these cannons requires expensive scaffolding. Quite often no work is done to keep these cannons working. It is also very difficult for the plant to determine if these cannons are even functioning.
Many applications require mounting numerous air cannons close together, one for each nozzle. This restricts or prohibits the ability of plant personnel to perform other required duties in this area. If more cannons are needed in the future it is very difficult to add any in these situations.
These and other limitations have been accepted for many years. The new Multiplier, or Super Cannon, minimises or eliminates these standard air cannon drawbacks. IGS can apply one single air cannon to a Multiplier system that replaces multiple single traditional air cannons offering many benefits over traditional air cannon installation.
Remote mounting of traditional air cannons has long been discouraged by air cannon companies. The thinking was the air cannon blast would lose its effectiveness over a length of pipe connecting to the nozzle. IGS has overcome this antiquated way of thinking by creating greater force and using a larger volume of air which maintain the blast power even through lengthy pipe runs. This combined with innovative nozzle technology and application experience have proven that mounting the air cannon in accessible locations is not only possible, but is the way air cannons will be applied in the future.
Smooth solution for air cannon drawbacks
Following a thorough evaluation and multiple consultations with IGS technical experts, a solution was identified and installed at the cement plant. A three-port multiplier with high-velocity nozzles was fitted. The high-velocity nozzle produces a high energy ball of air, moving material better than a wide thin blast of air from a fan jet nozzle. Increased air tank volume would now make the sticky material easier to move. New discharge locations have now made it possible to push the material downward, at the angle of the chute, instead of across the chute. Any working cannons were relocated.
The IGS Multiplier coupled with a larger 300L air cannon combined the initial power of the blaster with the large moving mass of the pusher to effectively clean this chute where other cannons had been ineffective. This mix of blast types allows the operator to not only break up hardened build-up, but also then shove it out of the way.
As a result of the IGS Big Blue air cannon installation, manual cleaning was no longer necessary. The plant is now evaluating further areas, where build up is a problem, for additional air cannon upgrades.
Efficiency and innovation are major drivers in the current climate. Cement plant managers, therefore, look for vendors that are able to fortify their resources by taking traditional systems and enhancing them for better performance. Eventually, what may now be considered “new” will become a new standard of cleaning.
The success of this installation allowed this plant to elect to purchase 75 additional air cannons to install on its preheat tower. The air cannons are part of a project to switch fuels. The plant is moving away from the expensive low-sulphur coal to a high-sulphur pet coke. It is established this change will create significant build-up in the preheat tower. The plant worked with IGS to best determine the location of auxiliary air cannons. Each air cannon is being supplied with the high-velocity nozzles.