Bulk handling is evolving in terms of safety, efficiency and automation.
The higher production demands in all bulk handling segments require increased efficiency at the lowest cost of ownership, in the safest and most efficient manner possible. As conveyor systems become wider, faster and longer, more energy production and more controlled throughput will be required. Add an increasingly stringent regulatory environment, and cost-conscious plant managers need to take a close look at which new equipment and design options match their long-term goals for the best return on investment.
Safety at higher belt speeds
Security is likely to become a new source of cost reduction. The percentage of treatment facilities with a strong safety culture is likely to increase over the next 30 years to the point of becoming the norm, not the exception. In most cases, with only a marginal adjustment in belt speed, operators quickly discover unforeseen problems in existing equipment and workplace safety. These problems are usually indicated by the greater volume of the spill, increased dust emissions, belt misalignment, and more frequent equipment wear and failure.
Larger volumes of cargo on the belt can produce more spills and fugitives around the system, which can present a trip hazard. According to the US Occupational Safety and Health Administration, slips, trips and falls account for 15% of all workplace fatalities and 25% of all workplace injury claims. Additionally, higher belt speeds make pinch and shear points more lethal in the conveyor, as reaction times are dramatically reduced when a worker is caught in clothing, tool, or limb by accidental contact.
The faster the tape, the faster the tape moves and the harder it is for a tape tracker to compensate, resulting in spillage all the way the tape is in. Caused by off-center cargo, seized tension rollers, or other reasons, the belt can quickly make contact with the main frame, chipping the edge and potentially causing a friction fire. Beyond the consequences for safety in the workplace, the belt can carry a fire throughout the installation at an extremely high speed.
Another danger in the workplace, which is increasingly regulated, is that of dust emissions. An increase in cargo volume means more weight at higher belt speeds, causing more vibration to the system and resulting in reduced air quality due to dust. In addition, the efficiency of the cleaning blade decreases as volumes increase, causing more fugitive emissions as the web returns. Abrasive particles can foul rolling components and cause them to seize, increasing the possibility of a friction fire and increasing maintenance costs and downtime. In addition, inferior air quality can lead to fines and forced shutdowns by inspectors.
Modern chute design
Wider and faster conveyors are deployed to reduce the cost per tonne of material transported. Traditional trough designs will likely remain a standard, but the push towards wider, higher-speed belts will require a substantial development of more reliable components, such as rollers, impact beds, and chutes.
A major problem with most standard chute designs is that they are not designed to handle increasing production demands. Unloading bulk material from a transfer chute onto a fast moving belt can displace the flow of material through the chute, causing off-center loading, increasing the discharge of fugitive material and emitting dust long after leaving the area settling. The result of off-center loading is poor tracking and spillage around the system and gateways.
New transfer chute designs help center material on the belt in a well-sealed environment that maximizes throughput, limits spills, reduces fugitive dust, and minimizes the risk of common workplace injuries. Rather than materials falling with high impact directly onto the belt, the descent of the cargo is controlled to promote belt health and extend the life of the impact bed and rollers by limiting the force of the cargo in the loading area. Reduced turbulence is easier on the wear liner and baseboard, and reduces the risk of fugitive material getting stuck between the skirt and the belt, which can cause friction damage and belt fraying.
Longer and taller than previous designs, modular stilling zones allow cargo to settle, providing more space and time for the air to slow down, so dust settles more completely. Modular designs easily adapt to future capacity changes. An outer wear liner can be changed from outside the chute, rather than requiring unsafe entry into the chute as in previous designs. Chute covers with internal dust curtains control airflow along the chute, allowing dust to clump on the curtains and eventually fall back onto the web in larger clumps. And double skirt sealing systems have a primary and secondary sealing strip in a two-sided elastomeric strip that helps prevent spills and dust from escaping from the sides of the chute.
Rethinking belt cleaning
Faster belt speeds can also result in higher operating temperatures and increased degradation of the cleaning blades. Larger volumes of cargo approaching at high speed struck the primary blades with greater force, causing some designs to wear out quickly, resulting in more recoil and increased spillage and dust. In an attempt to compensate for the reduced equipment life, manufacturers can reduce the cost of belt cleaners, but this is an unsustainable solution that does not eliminate the additional downtime associated with the belt cleaners. maintenance of the cleaner and regular blade changes.
While some blade manufacturers struggle to keep up with changing production demands, industry leaders in conveying solutions have reinvented the cleaning industry by offering rugged polyurethane blades that are made to order and cut on site. to ensure the freshest and most durable product. Using a torsion, spring, or air tensioner, primary scrapers are forgiving to the belt and splice, but are still very effective at loosening residue. For heavier applications, a primary cleaner design includes an array of tungsten carbide scrapers installed diagonally to form a three-dimensional curve around the head pulley. Field service has determined that it typically provides up to four times the life of urethane primary cleaners, without ever needing to re-tighten.
Taking belt cleaner technology into the future, an automated system increases blade life and belt health by removing blade contact with the belt whenever the conveyor runs empty. In addition, it reduces the labor for constant monitoring and tensioning of the blades to ensure optimum performance.
Connected to a compressed air system, the pneumatic tensioners are equipped with sensors that detect when the belt is no longer loaded and automatically reverse the blade, thus minimizing unnecessary wear on the belt and the cleaner. The result is consistently correct blade tension, reliable cleaning performance, and longer blade life – all managed without operator intervention.
Bulk handling, safety and automation in the future
Automation is the way of the future, but as experienced maintenance personnel retire, young workers entering the market will face unique challenges as safety and maintenance skills become more and more important. in addition to sophisticated and essential. While still requiring basic mechanical knowledge, new maintenance personnel will also need more advanced technical knowledge. This division of labor requirements will make it difficult to find people with multiple skills, which will push operators to subcontract certain specialized services and make maintenance contracts more frequent. Eventually, the monitoring of conveyors related to safety and predictive maintenance will become more and more reliable and widespread, allowing conveyors to operate autonomously and to forecast maintenance needs.
Author: Todd swinderman
CEO Emeritus, Martin Engineering