Acoustic Leak Detectors for Combined Cycle HRSG Boilers

Acoustic Steam Leak Detection systems has been used successfully for decades as a valuable tool for the management of boiler tube steam leak for early tube-leak detection on coal fired boilers and is being utilized now by Combined Cycle Power Station with Heat Recovery Steam Generator (HRSG).  The system provides a means by which boiler tube leaks can be detected before they can otherwise be detected with traditional methods. The system is designed to give the maximum warning of a forced outage that is due to a tube leak. Early detection of leaks provides the time and information that will allow the engineers to identify, locate, evaluate, monitor and plan the engineering procedures to make repairs to the boiler.

The Acoustic Steam Leak Detection system consists of multiple sensors strategically located around the HRSG that continuously monitors the ambient background sound and can be installed to the boiler tubing, header piping, attemperators, feedwater heaters, and anywhere where there is pressurize steam/air/water.  These sensors have two output signals, one signal is processed such that the unwanted sounds in the boiler are attenuated and the sound of a tube leak amplified.  The second signal enables the user to listen to the actual sounds inside the boiler.

Basic HRSG background:

For Combined Cycle HRSG unit’s severe thermal and mechanical fatigue damage to the boiler tubing and steam piping can be attributed to quenching from the attemperators which continues to be a problem. Each HRSG boiler produces a different sound and will therefore produce a different level of back ground noise. However experience with many leaks and many boilers have shown us that a level of 94dB is a reliable threshold where a leak is probable. A sudden unexplained increase in signal level will cause an alarm and should be investigated. It is common that a leak will produce an increase in sound level on more than one sensor. This can be achieved using the dedicated computer program available from Greenbank Energy or the station DCS computer. 

For Natural Gas Electricity Generators there are:
  • Combined Cycle HRSG Boilers with Gas Turbines
  • Gas Fired Boilers
  • Simple Cycle Turbines
  • Coal Fired Boiler Co-Fired with Natural Gas
  • Coal Fired Boiler converted / Retrofitted to Natural Gas 
  • Other Natural Gas configurations exist but these are the most prevalent
The Greenbank Energy Solutions (GESI)  LA 202 Acoustic Leak Detection System is the longest standing system of its type available. Since 1974 there have been over three-hundred systems installed worldwide.  The modular, expandable system has been designed to meet virtually every application requirement for performance and economy.
Research has proven that true acoustic measurement of sound level in a confined space is more accurate through a wider band width than indirect piezo measurement. However, to provide the ultimate system flexibility, GESI can provide either airborne or structure borne sensors as the application requires.
Damage to steam and water piping systems by corrosion, thermal-mechanical fatigue, or slagging has long affected conventional coal-fired boilers. HRSG designs can be affected by some of these issues as well, causing unscheduled outages and lost revenue.
A well-designed acoustic leak detection system enables operators to continually monitor and trend real-time performance of various systems in the unit and provide early detection of a potential problem. Strategically placed sensors enable operators to safely determine the location of a leak or malfunction and schedule required maintenance based on severity. The modularity of the LA202 system allows for additional points to be added at any time with minimal cost and effort.
Typical Applications:
  • Boiler Tubes
  • Superheater / Reheater
  • Main Headers
  • Waterwalls
  • Attemperators
  • Isolation Valves / Relief Valves
  • Pipeline Flow / No Flow



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