Electricity + Control July 2019

FLOW MEASUREMENT + INSTRUMENTATION round up

Boiler tube leak detection systems

can detect small leaks before they become catastrophic failures. "A leak in a boiler tube can start as small as a pinhole – and remain undetected for a long time. Eventually, the hole will grow to a point where it leads to a major tube burst. When such an incident happens, there can also be expensive secondary damage inside the boiler," Fraser points out. A further key advantage of the Procon system is the number of microphones installed in a boiler. For example, a typical power station might have as many as 24 acoustic devices installed in a boiler.The output from the 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 system analysis, all data can be printed. When a leak occurs, the microphone nearest 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. “Power station technicians can then look at the computer display and, judging from the varying sound levels from the microphones, predict with some precision where the leak is,” Fraser 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. With the evidence from the Procon system, technicians are aware there is a leak and can search for it until it is found. The Procon detection system also enables technicians to assess the seriousness of a particular leak. Depending on their assessment, a maintenance shutdown can be planned and scheduled so the impact of the downtime is minimised. In South Africa, Procon tube leak detection systems are in use at Medupi and Kusile power stations and on the six boilers at Arnot power station. "Compared to the cost of a boiler failure in a major power station, the cost of the Procon system is minimal," continues Fraser, adding that the system becomes increasingly cost-effective on larger boilers of 200 MW capacity and more. He notes too that 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. "With boilers that service manufacturing or production environments, prevention of major failures is just as critical and will also assist in preventing the potential costs of damages and downtime,” says Fraser. RTS Africa serves clients across a wide range of industry sectors such as mining, power generation, petrochemicals, glass, steel and energy. Enquiries: RTS Africa Group. Tel. +27 (0)12 433 6335 or visit www.rtsafrica.co.za

RTS Africa Technologies, a division of the Tshwane-based RTS Africa Group, offers a range of instrumentation-related solutions to address various industrial and process challenges. These include laser-based gas detection devices for use in hot and corrosive environments, and boiler tube leak detection systems. The boiler tube leak detection system is from UK-based principal Procon Engineering, the company that invented the technology and is still today a global leader in the field. According to Ian Fraser, Managing Director of the RTS Africa Group, with more than 250 installations in over 20 countries worldwide, Procon Engineering can claim more experience and success than any other company in boiler tube leak detection. Early detection of boiler tube leaks provides for safety of personnel, longer tube life, and most importantly, continued availability of the system. “Early tube leak detection means unscheduled outages can be avoided, or at least reduced,” says Fraser, “as can repair costs and secondary damage, with the attendant reduction in financial penalties and insurance costs.” Fraser explains that Procon manufactures specialised microphones that are designed to detect the particular noise made by steam leaking from a boiler tube. “The sound of a boiler tube leak has a particular frequency which Procon microphones can selectively detect. This in itself is quite a technical feat, as the firebox of a boiler is a fairly noisy environment,” Fraser says. The microphones are installed at the end of long steel tubes which target specific points in the boiler tube system. As there are usually high levels of soot in boiler fireboxes, as an option, the Procon acoustic detectors can also be fitted with an air pulse system which clears the soot deposited in the tubes. The key benefit of the Procon leak detection system is that it

Purpose-designed microphones are installed at specific points in the boiler tube system to detect leaks.

Electricity + Control

JULY 2019

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