Commonly used in many production processes to vertically lift bulk solids, continuous bucket elevators are a key conveying technology that many facilities depend upon for efficient material handling.
An aspect often overlooked with continuous bucket elevators is the need to consider how material is fed into the unit. As an equipment type, bucket elevators require a controlled infeed of material to operate effectively. Failing to consider how material will be presented to the conveyor can result in lost throughput, product degradation, and equipment damage and downtime.
①Consider the Method of Infeed Control Required
Bucket elevators can receive material from a variety of upstream process equipment, including mixers, blenders, dryers, pastillators, etc. Irrespective of the equipment type, it is critical to evaluate how the flow of material will be regulated as it enters the elevator infeed. To perform effectively, bucket elevators require a uniform and consistent rate of feed.
②Consider the Infeed Orientation
For continuous bucket elevators, it is preferred to feed material “in line” to the elevator infeed as opposed to, for example, feeding at right angles to the elevator infeed. Feeding material inline to the elevator infeed permits a more even distribution of material across the width of the buckets. In contrast, feeding the elevator perpendicularly can result in uneven material distribution within the buckets, as well as causing increased bucket wear that results from the more concentrated impact of material. The latter point is a particularly important consideration when moving abrasive materials or heavy products through the elevator. This can be resolved by incorporating a bias cut to either the transition chute, or vibratory feeder tray.
③Consider the Material Drop Height
Minimizing the height from which material is dropped into the elevator reduces product dusting and allows for a gentler transfer of material. Ensuring a gentle transfer minimizes particle attrition and is important when handling fragile or friable materials that could degrade when dropped into elevator from too high a height. In addition, minimizing the material drop height reduces impact wear on the buckets, reducing the need for maintenance interventions and replacement parts.
④Consider the Equipment Start-Up Sequencing
To ensure that no load is present at start-up, the elevator should be started and allowed to “ramp up” to the desired operating speed before being fed with material. This can be accomplished by setting an appropriate time delay on the control device used to regulate the flow of material into the elevator infeed. The time delay ensures that no material enters the elevator until the operating speed is reached, avoiding any potential damage to the conveyor.
⑤Consider the Need for Any Transition Chutes
Transition chutes contain and direct material as it transfers from an upstream process into the elevator infeed. Material containment is particularly important when handling hazardous or toxic materials, which usually require fully enclosed connections. These sealed connections would be made either using a direct “flanged” or a “flexible” type. Transition chutes should be designed with a geometry and size that allows for a controlled and even flow of material through the chute and into the elevator.
