South Africa experiences regular power outages that are often blamed on power generators being shut down owing to boiler tube leaks, but a well-established and proven solution is available from engineered solutions specialist and supplier RTS Africa Technologies – accredited agents and service engineers for Procon Boiler Tube Leak Detection, based in the UK.
The well-proven Procon technology offers an effective system that can detect leaks that may occur in boiler tubes – long before they grow to the point where they cause a tube burst that results in the boiler having to be shut down.
When this happens at one of the large new power stations, a shut down immediately removes 800 MW off the grid. A leak in a boiler tube can start as small as less than 1 mm – and remain an undetected problem for an extended period of time.
Of course, it is not only at power generation plants that boiler tube leak detection offers advantages. Many industrial plants operate large boilers that are critical to maintaining plant processes. When their boilers experience a tube leak, this can even lead to a complete plant shutdown, resulting in significant loss in production and revenue.
Procon Boiler Tube Leak Detection systems provide a continuous diagnostic tool that enables plant operators to identify and locate a leak, long before it results in 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.
The system consists of a series of specially designed microphones (acoustic sensors) that are installed at strategic positions around the boiler. Procon’s many years of experience enables them to recommend the optimum number and position of microphones on any particular boiler. These sensors are tuned to detect the particular sound frequencies emitted by a steam leak. The audio band sound pressure waves from inside the boiler pass along the acoustic waveguide which functions as a ‘listening tube’ where they are detected by the Airborne Transducer mounted at the end of the waveguide.
The airborne sensors can detect a 1 mm to 2 mm hole at 10 m in clear space. All transducers contain a sound, or vibration, generating element to enable on-line functional tests to be made by operational staff from the control room. This feature is unique to the systems offered by Procon.
The signal from the microphone is converted into a 4-20mA signal which is sent to the central diagnostic console. A bar graph display provides individual sound level indications for each sensor on the monitor screen, up to a maximum of 48 channels. A boiler diagram [Mimic] is provided on the monitor screen to show the location of each sensor on the boiler.
The operator may interrogate the system via a keyboard/mouse terminal to change the display page to select bar graph display with alarm messages; boiler mimic diagram with alarm messages; signal trend display, 10 min to 60 days period [up to 8 channels]; system test with alarm legends and frequency spectrum.
It is important to note that the Procon Boiler Tube Leak Detection system is a diagnostic tool that needs to be continuously monitored and interrogated. The system is readily accessible, and a designated operator can easily observe a rising sound trend on one or more channels which enables this data to be logged and used to locate the leak at the next shutdown. If the leak has existed for some time, the origin can be traced on the Signal Trend Display.
RTS Africa Technologies can provide the complete package – including initial design, installation, training, and ongoing support.
At this time, Procon Boiler Tube Leak Detection equipment is installed at both Medupi and Kusile power stations and some years ago RTS Africa carried out a full installation at Arnot power station in Mpumalanga.