Advances in conveyor belt condition monitoring.
Conveyor belts are vital links for moving mined material or products to a processing plant. When a conveyor belt breaks or its operation is halted for unscheduled maintenance, it can cause large losses in production as well as repair and clean-up costs. The loss of major belts at large facilities can quickly escalate to millions of Rand, even from a single belt failure, where such downtime can be days rather than hours. For this reason, predictive maintenance systems that accurately plot conveyor condition and degradation over time are invaluable to plant managers.
Types of damage usually sustained on a belt include steel core damage caused by foreign bodies cutting into the belt at the loading chute and product entrapment under the rollers (steel-core conveyor belts are widely used for long overland conveyors), surface damage, bad tracking, edge damage, splice failures and longitudinal rips.
Belt inspection is typically carried out by visually monitoring surface condition, magnetic monitoring of steel cores, X-ray imaging and vibration monitoring. The cost of such systems is typically less than the cost of a single conveyor failure or stoppage caused by unscheduled maintenance on large plants.
A new generation of conveyor belt condition monitoring and inspection systems is appearing that can monitor belt damage and forecast belt failures by combining a number of these into a system dedicated to increasing belt life through decay analysis and to stopping catastrophic failure through timely intervention.
The BeltView and BeltWatch conveyor condition monitoring systems developed and marketed in South Africa by Westplex detect all the types of damage listed above, and are at the forefront of this field. Both systems include multi-channel magnetic core monitoring, high resolution visual inspection and accurate tracking measurement. Further development to include X-ray imaging is planned.
These systems combine the power of high resolution computer based visual inspection with a multichannel magnetic steel core monitor. They include accurate tracking and belt width measurement. All this information is synchronised to produce a wealth of raw data upon which a comprehensive analysis of surface defects, buried steel core faults, tracking and alignment issues can be performed.
Two methods of condition monitoring can be done:
Periodic belt surveys (BeltView)
A detailed inspection of the belt can be conducted at time intervals specified by the belt owner. The data captured provides a synchronised view of the belt surface in high definition imagery overlaid on the magnetic signature of the cord condition and the tracking data of the belt. All the splice positions are displayed for reference purposes. Once reviewed and analysed, maintenance recommendations can be created in the automatic report generator for use by the correct personnel.
The BeltView system is portable for use by dedicated personnel, such as a Condition Monitoring department.
Periodic surveys have a number of advantages:
* A highly detailed analysis can be made of belt surface damage caused by mechanical intrusions, scrapers or seized idlers. This is a significant cause of belt life deterioration where the surface is simply worn away.
* The magnetic signature read with the visual data provides very accurate positional and overview information of damage spread and type. This is used to determine trends in damage increase and severity, which is used to schedule repairs and replacements.
* A detailed recording of the whole of the high resolution belt surface image and the magnetic signature can be archived for later comparison.
* A lower capital cost to a plant that has more than one conveyor.
However, defects or failures that occur on a time-scale shorter than the survey time intervals (eg, three or six months) can possibly result in catastrophic failure as there is no realtime monitoring.
On-Line systems (BeltWatch)
Beltwatch is a permanently installed monitoring system that continuously monitors steel core belt magnetic signatures, tracking and (optionally) surface images. The system consists of a rugged computer linked to permanent mount magnetic, tracking and vision sensors, which can optionally be linked to a control room computer and display system.
On-line systems have the advantages of:
* Continuous on-line measurement of steel core and tracking.
* Immediate warnings of deterioration and failures.
* Link to scada systems with multipriority alarm features.
* Optional live control room displays of tracking, defects and surface images, with report generation facilities of all belts in a production facility.
* Optional surface images of events.
However, on-line systems have higher capital costs to a plant that has multiple conveyor systems.
Either system provides essential condition monitoring and maintenance management information, and can pay for itself by the avoidance of one unforeseen conveyor belt failure.
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version