Reducing Belt Drift and Improving Rate
Clean Plant automated hosing can help significantly reduce belt drift.
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How Clean Plant automated hosing can reduce belt drift and improve rate
Bulk material conveyors utilise the engineering principal of positive stability, such that when the centre of mass shifts away from a centre position a restoring force is generated directing the mass back towards the centre.
A simple analogy of this phenomenon is to consider that the trough idlers of a conveyor are a ramp, with it being easier for belting to roll downwards toward the centre of the conveyor than it is to move upwards.
An undesirable consequence of this phenomenon is that if the centre of mass (bulk material) is out of alignment with the belting centreline, the bulk material will still track towards the centre regardless if the belting itself is pushed beyond the edge of the conveyor.
Plant protection devices, known as belt drift detection, are in place to identify belt drift and prevent catastrophic damage to plant and personnel. Detection devices trip when the belting itself moves off centre, with the off centre allowance prior to activation often being as little as 100mm activation, effectively a 100mm variation between the centre of mass of the bulk material and the belting centreline.
With as little as 100mm of bias loading resulting in a drift event, performance of the conveyor belt is heavily dependent upon the material loading performance, and design of the transfer chute and loading profile of the feed conveyor. A major limitation of bulk material transfer design is the assumption that geometry of the transfer chute once in service remains constant and unchanging, an assumption that is fundamentally false without the ability to ensure that the geometry remains consistent after construction.
In order for flow surfaces to be effective and maintain optimal rates without spillage or induce conveyor belt drift relies upon the surface geometry of the process surface remaining constant and free from build up. This is a task many operations teams are not resourced to undertake as access to the process surface is not readily accessible without isolation and the removal of guarding. For example, a flow surface adjusted one day to be effective can become ineffective the next as build up develops or if the surface was set with build up present.
This industry challenge results in plant trips or unscheduled loss events impacting performance metrics. An industry technique to achieve performance metrics and prevent downtime is the concept of reducing rates in order to prevent plant trips from occurring. The technique works by reducing the mass (weight) on the conveyor belts and in turn the forces pushing the belting towards belt detection devices lowering the likelihood of a belt drift event occurring and delaying the need to stop and hose the transfer chutes.
Although effective at preventing plant trips and reducing unscheduled loss, the practice results in significant lost opportunity. The process plants operate at reduced output for extended periods of time. Only minutes would have been required in order to restore the plant to optimal production if it had not been for the requirement to bring the plant to a stop, and mobilise an operator in order to complete hosing activities.
Clean Plant automated hosing enables operators to remove process material build up from process control surfaces such as loading boots, deflector plates and diverter gates frequently and automatically without the need to expose plant operators to the process plant equipment. Furthered by increasing frequency of hosing events, the equipment is able to operate at its optimal design capacity consistently without the need to stop for cleaning, or at reduced rates to prevent spillage, or require high manning levels.
When compared to administrative such as lowering rate, or the implementation of mitigating engineering controls such as the implementation of guilders, eliminating a root cause of conveyor drift through the implementation of automated and frequent hosing enables operators to: