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CRC Mining have investigated the application of fibre optic Distributed Acoustic Sensing (DAS) for conveyor roller condition monitoring. This is the final report of project C24014.
Monitoring by means of acoustic distributed sensing can be achieved by using a single fibre optic cable coupled to a laser source and a signal detection-recording unit in order to measure, for example, strain and temperature at thousands of locations along the fibre, simultaneously. Also, by installing a fibre optic cable along the length of a conveyor a DAS interrogator (detection-measuring-recording) unit of a certain type can detect and report vibrations from any location along the conveyor to a resolution of, say one linear metre, or less, depending on the design of the interrogator. This project explored the application of such monitoring concepts to monitoring the operating conditions of equipment in real mining environments.
This project evolved from an earlier seed-research study.
The earlier work by CRC Mining, involved conducting preliminary testing of a single-pulse DAS interrogator unit monitoring vibration phenomena of conveyor rollers at the Queensland Coal Bulk Handling facility (QBH). The data collected during this initial trial was only later processed and analysed as a scope activity with the aim of developing suitable algorithms cable of discerning from the large and periodic time-domain acoustic frequency data sets the spectra that characterised any different stages of failed rollers/bearings. Given the linkages, this report includes references to the early analysis and first-generation algorithms that were developed.
Following a second set of field trials of a DAS conveyor monitoring system carried out at Dawson in 2015, further mathematical and algorithm developments were pursued. Earlier data sets were systematically re-processing while testing the new processing routines. The subsequent advances in data processing led to the identification of interim technology gaps prompting a third series of DAS control tests being required, which were carried out during June 2016 on an operating coal-transfer conveyor at the Queensland Bulk Handling. In parallel, lab tests were also complete using a lab testing rig at the CRC Mining campus.
As a result of the analysis it has been shown that the DAS technology is capable of detecting, with some precision, the condition and state of wear of the bearings in conveyor rollers and it is possible to pinpoint which roller; and in some cases the exact bearing along the conveyor structure that are damaged. It has also been shown that there are differences in results arising from the way the fibre is used and set up and the selection of settings on the DAS interrogator unit.
This project explored the functionality of a DAS conveyor monitoring system and further determined key requirements of operability and minimum technical specifications that will drive the design and the testing of a deployable version.
A separate second phase of work has been completed. The project is C25054. A final report for C25054 is available from the ACARP website.