Power generation facilities can benefit from using turnkey solutions provider Procon Engineering’s boiler tube leak-detection to avoid unplanned shutdowns, says industrial and processing solutions provider RTS Africa Technologies MD Ian Fraser.

“This equipment provides a continuous diagnostic tool that enables plant operators to identify and locate a leak, long before it results in a tube burst that causes an unplanned shutdown. "Maintenance crews then have the opportunity to locate and repair the leak during the next scheduled shutdown, avoiding loss of generation capacity at crucial times.”

Fraser emphasises that this is especially helpful, as leaks in a boiler tube can be smaller than 1 mm and can remain undetected for a long period.

He also reiterates the importance of this solution at power stations, particularly State-owned power utility Eskom’s power stations, as a shutdown could remove 800 MW from the national power grid.

The equipment includes a series of specially designed microphone and acoustic sensors that are installed at strategic positions around a boiler. Fraser says Procon’s years of experience enable it to recommend the ideal number and position of microphones on any boiler.

The sensors are tuned to detect specific sound frequencies that are emitted by a steam leak. The audio band sound-pressure waves from inside the boiler pass along the acoustic wave guide. This functions as a “listening tube”, where they are detected by the airborne transducer mounted at the end of the wave guide.

The airborne sensors can detect a hole of 1 mm to 2 mm at 10 m in clear space. All transducers contain a sound- or vibration-generating element to enable operational staff to conduct online functional tests from the control room.

If a leak has existed for an extended period, the cause of the leak can be traced on the signal trend display, as the solution is based on identifying a rising noise trend within a boiler, Fraser states. The signal trend display can illustrate trends in a period of between 10 minutes and 60 days.

Fraser stresses that this feature is unique to the equipment offered from Procon.

RTS Africa Technologies can provide a complete solution, which includes initial design, installation, training and ongoing support.

Fraser highlights that, currently, Procon boiler tube leak-detection equipment is being installed at Eskom’s Medupi and Kusile power stations. Ten years ago, a full installation at Arnot power station, in Mpumalanga, was also completed, with RTS Africa still involved with regular replacements for microphones and amplifier cards.

He mentions that this equipment can be installed on any conventional boiler. In theory, installations such as this should virtually eliminate unplanned shutdowns from boiler tube leaks.

Improvements and New Markets

Last year, RTS started to investigate the option of offering simpler display and diagnostic options for testing systems, which would make them more cost effective for smaller boilers.

Fraser confirms that, since then, progress has been made, enabling RTS to offer this solution for smaller systems with only a few acoustic channels.

“It’s a simple matter of capital cost. The standard diagnostic system consists of a 19-inch rack and a fully computerised diagnostic system. The smaller systems will use a less complex display, and recording systems will be set up for a small number of channels,” he stresses.

Any further updates to the system would purely focus on improvements in terms of stability and reliability.

While the system is imported from Procon, in the UK, Fraser states that RTS does provide local hardware, such as acoustic tubes and IP65 enclosures for the amplifiers, for the system.

He highlights that the local market for this equipment would need to be larger before the company would consider manufacturing the equipment locally.

While the benefits of this system for power stations are clear, Fraser adds that the company’s marketing campaign is “to attract the attention of any boiler operator who is at risk of experiencing costly and unscheduled boiler failures from tube bursts”.

RTS Africa Technologies is an accredited distributive agent and service engineer for Procon Engineering products in sub- Saharan Africa.