Primetals Technologies introduced unique acoustic monitoring systems known as the Material Screening Monitor, Material Type Monitor, Torch Cutting Monitor, Bag Cleaning Monitor, Discharge Monitor, and Grain Size Monitor. These systems detect sound deviations from the normal state and allow condition-based maintenance activities to be initiated before potential damage can take place. In combination with a new cloud service, evaluation of the sound emitted from steel-plant equipment is carried out, and this information can be accessed at the touch of a finger—24 hours a day, 7 days a week. In 2016, an acoustic monitoring system was put into operation for the first time in a dedusting plant at voestalpine Stahl GmbH in Linz, Austria.
Designed on a bionic basis, acoustic monitoring systems are able to continuously monitor all plant equipment and components that emit a specific sound spectrum. Plant noise is generated, for example, by electric arc furnaces, the nozzles of torch-cutting machines in continuous casting plants, motors, drives, switching relays, and valve stations.
Whereas people find it difficult to detect gradual wear, the acoustic monitoring systems utilize long-term analyses of emitted sound. The systems employ an industrial microphone, a monitoring system, and an evaluation system.
First Application
The acoustic monitoring systems were put to the test for the first time ever in the dedusting system of a secondary metallurgical plant. In this application example, the Bag Cleaning Monitor analyzed the sound caused by the cleaning valves of a pulse-jet bag-filter plant. The profile of each cleaning pulse is recorded in 500-ms-long intervals and evaluated immediately afterwards. Audio data is recorded for analysis only and subsequently deleted after processing. Furthermore, the Bag Cleaning Monitor and other acoustic monitors do not sample human voices. Following data evaluation, the results are visualized in the customer’s HMI (human-machine interface).
Example of Acoustic Monitoring and Evaluation Results
The condition of the three pulse-jet bag-filter valves was monitored with the Bag Cleaning Monitor. For one valve, everything is working within an acceptable range, while another valve showed a decrease in performance, suggesting gradual wear on the valve membrane. Gradual equipment wear is particularly difficult to detect, and in some cases, it is discovered too late, namely, once the problem becomes evident. With the online Bag Cleaning Monitor, such wear can be detected earlier through historical trend analyses and interpretation. The final valve was also only found to be operating at 40% of its performance capability, therefore requiring maintenance or replacement.
System Flexibility
In combination with an online connection, it is also possible to utilize the Bag Cleaning Monitor as a cloud-based service. In this case, the system can be separated from the local IT network to enable a fully stand-alone monitoring solution. All in all, the system increases the plant-information level and contributes to increased plant productivity through the avoidance of equipment failure.
Success Story
The Bag Cleaning Monitor was installed and put into operation in a secondary dedusting plant of voestalpine Stahl in Linz, Austria, in January 2016. The sound spectrum emitted by the pulse-jet valves during cleaning of the bag filter is analyzed, and any deviation from normal plant operation is detected by the acoustic system. Condition-based maintenance instructions are submitted to maintenance personnel via mobile devices. The Bag Cleaning Monitor was implemented at voestalpine, installed in one day without any plant stoppages, optimized in just two days, and brought into operation two months before the scheduled date.
