How to Find Tube Leaks in the Superheater

Over half of boiler outages occur because of tube leaks, and boiler outages are the major cause of generation loss in power plants. When tube leakage occurs in the superheater and reheater, it is even more serious. That’s why power plants must be proactive about the maintenance and repair of boiler tube leaks, so secondary damage to other pressure parts, including superheater tubes and reheater tubes, can be avoided. The expenses involved in the repair or replacement of secondary damage can be costly.  

Unfortunately, even the most diligent monitoring and maintenance may not be enough to completely prevent a superheater tube leak. And if that happens, the leak may be challenging to find because it may not be something that you can see to pinpoint. Acoustic monitoring leak detection systems are designed to help locate tube leaks so they can be repaired quickly, minimizing downtime and avoiding power outages for consumers.  

Acoustic Monitoring vs. Traditional Methods of Detecting HRSG Tube Leaks

Using acoustic monitoring to identify tube leaks in steam generators isn’t a new technology. It’s been used for years in conventional steam plants and recovery boilers at pulp and paper plants. However, relatively recently, acoustic monitoring has been modified for use in heat recovery steam generators.

Traditionally, leak detection systems were limited to hearing a leak audibly or detecting vacuum fluctuations. Those methods work for larger leaks but are not sensitive or reliable enough to detect small leaks that are still in the early stages. The time it takes for a small, undetected leak to get big enough to be detected by conventional methods can lead to power plants running for extended periods with unnoticed tube leaks, leading to even more damage.

Acoustic monitoring systems use microphones and sensors to detect leaks in their early stages. These leak detection systems detect high-frequency sounds that are emitted from tube leaks, and piezoelectric sensors that have been attached to the boiler structure convert these waves into electronic voltage. The voltage is amplified, filtered, and then processed to specify the amount of leakage and the location of the leak. The system is monitored online, so hardware and software are both required for acoustic monitoring.

Acoustic Monitoring is used to:

• Detect leaks earlier than traditional methods
• Reduce secondary damage
• Locate the area of a leak before the unit comes offline
• Trend the severity and progression of the leak with real-time data
• Schedule a maintenance outage rather than a forced outage
• Pre-plan jobs with correct assets
• Manage market exposure and risk
• Avoid shadow loss of generation/production
• Provides additional safety measures for high-risk areas

The Value of Acoustic Monitoring in Finding Tube Leaks

Acoustic monitoring detection systems for boiler and superheater tubes are cost-effective because they are able to detect leakages in the early stages so they can be mitigated before more extensive damage occurs. As a result, it lowers the cost of repair and frequently decreases the amount of downtime required to make repairs.

For example, in a power plant, a superheater leak may be identified when there is a gradual increase in a signal level. That allows teams the time to create an operations plan to keep the unit running, but at a low load in the evening, rather than shutting it down. This may allow the HRSG to operate for several weeks so that an outage for maintenance and repair can be planned instead of an emergency.

SVI/Bremco for HRSG Tube Repair

At SVI/Bremco Dynamics, we are committed to providing exceptional services to our industrial plant clients, including those using HRSGs. We know that optimizing all system components is critical to the efficiency and profitability of your plant. So, whether you need superheater tube maintenance, repairs, or replacements, our team of technicians and engineers can help. Contact us today for more information or to schedule a site visit.