MechChem Africa September 2019

South Africa’s national power supplier continues to contend with various complex challenges - including boiler maintenance issues caused by, amongst other factors, boiler tube leaks. RTS gives some industry solutions for a common problem. Leak detection system prevents boilers ‘going down the tubes’

Ian Fraser, Managing Director of the RTS Africa Group.

I t is reported by US-based organisation, the Electric Power Re- search Institute (EPRI), that power generation plants in the US and Europe have, ‘on average, around 6% loss of plant availability due to boiler tube leaks’ – a major loss factor for these facilities. InSouthAfrica,industrialsolutionsproviderRTSAfricaTechnologies has an effective solution to the challenge of boiler tube leaks. This is in the form of a boiler tube leak detection system from UK-based principal Procon Engineering, a global leader in the field of acoustic leak detection, which invented the technology and introduced it to the world in 1974. With more than 250 installations in over 20 countries worldwide, Procon Engineering can proudly claim more experience and success than any other company in the field. This is according to Ian Fraser, managing director of the RTS Africa Group. He explains that the benefits of the early detection of boiler tube leaks include increased operating profit, personnel safety, availability and tube life. “In addition, early tube leak detectionmeans unscheduled outages can be avoided or at least reduced; as can repair costs and secondary damage, with the attendant reduction in financial penalties and insur- ance costs,” he adds. Commentingonhowthe technologyworks, Fraser says that Procon manufactures specialised ‘microphones’ – which bear little resem- blance to conventional audio microphones. These detect the very particular noise made by steam leaking from a boiler tube. “The sound of a boiler tube leak has a particular frequency that Proconmicrophones are selectively able todetect. In itself, this is quite a technical feat, as the firebox of a boiler is a fairly noisy environment,” he advises. Themicrophones are installed at the end of long steel tubes, which target specific points in the boiler tube system. As high levels of soot

areusuallypresent inboiler fireboxes, as anoption, theProconacoustic detectors can also be fitted with an air pulse system that clears the soot deposited in the tubes. The Procon leak detection system can detect small leaks before they become catastrophic failures. This is of operational importance. “A leak in a boiler tube can start as small as a pinhole - and remain an undetected problem for an extended period of time. But, eventually, the size of this hole will grow to a point where the growing diameter of the orifice leads to a major tube burst. When such an incident hap- pens, there can also be expensive secondary damage inside the boiler,” Fraser explains. A further key advantage of the Procon system lies in the number of microphones installed in a boiler. For example, a typical power station might have as many as 24 Procon acoustic devices installed in a boiler. The output from the Procon microphones is fed into an IT- controlled display – each microphone being represented by a bar on the display. This shows the sound levels from each microphone inside the firebox. For record-keeping purposes and systemanalysis, it is possible toprint out the data from a Procon system. When the leak occurs, the microphone nearest to the leak will display an elevated bar level. What is particularly useful is that other microphones in the area will also pick up the noise. “Powerstationtechniciansarethenabletolookatthecomputerdis- play and - judging fromthe varying sound levels fromthemicrophones – predict with some precision where the leak is occurring,” he says. For boiler maintenance teams, this is most helpful, as even during physical inspections of the inside of a boiler and its tubes, a pinhole size leak can be difficult to detect visually. However, with the evi- dence from the Procon system in hand, technicians are aware that there is a leak and can search for it until it is found in the shortest possible time. What theProcondetection systemalsoallows is for power station technicians to assess the seriousness of a particular leak. Depending on their assessment of the extent of the leak, itispossibletoplanascheduledboilermaintenanceshutdown so the impact of the downtime is minimised. In South Africa, Medupi and Kusile power stations both employ Procon tube leak detection systems; and RTS Africa installeda completeProcon systemon the sixboilers atArnot power station some years ago. “Compared to the cost of a boiler failure in amajor power station, the cost of the Procon system is minimal,” continues Fraser, adding the proviso that the system becomes increas- ingly cost-effective on larger boilers of 200 MW capacity and more. “The Procon system has been designed not only to serve power stations; but also the host of boilers used in the broad spectrum of industry,” Fraser explains. “With boilers that might service manufacturing or production environments, prevention of major failures will also assist in the avoidance of punitive financial penalties, and ultimately bring about a marked improvement in the company’s bottom line,” he concludes. q

RTS Technologies’ systems are designed specifically to meet clients’ plant requirements.

22 ¦ MechChem Africa • September 2019