Inspecta Automatic Purge System is a cost-effective, ambient-air purge system that requires neither compressed air nor an additional power source to remove the fly ash build-up within the Inspecta pipe-sets, for leak detection in power stations.
Instrotech, which designed the successful acoustic steam leak detection systems (Inspecta ASLD), has now developed a fully automatic purging system that’s easily retrofitted to existing Inspecta installations. The installation of this system eliminates routine manual purging of the pipe-sets and maintains the leak detection system at peak performance, without manual intervention.
Installed in most of Eskom’s power stations, Inspecta ASLD systems use acoustic detection technology that detects tube leaks less than 2mm in diameter in the large boiler structure. The coal used in power stations is very high in ash content, so there is a considerable amount of fly ash remaining after combustion. This fly ash swirls inside the boiler and quickly blocks the ‘listening’ pipe-sets that contain the sensitive leak-detection microphones. Unless the systems are frequently cleaned (either manually or automatically) their ability to detect the leaks early, will be significantly degraded.
The proven Inspecta ASLD has been shown to reliably detect steam tube leaks. To achieve this accuracy, the system must be correctly calibrated and the ‘listening’ pipe-sets kept clear of any obstruction that will reduce the sensitivity of the system. Experience has shown that if there is any obstruction that reduces the sensitivity by more than 10%, it will result in a measurable degradation of the Inspecta ASLD and a delay in the detection of a tube leak. The resulting delay in detecting a tube leak may well result in extensive secondary tube damage and significantly extend the downtime to repair the damaged boiler.
Figure 1 shows that to optimise effective leak detection operation, the pipe-sets, located in particularly the combustion areas of the boiler, should be cleared of fly ash buildup every 1,5 to 2 hours. It is not practical to reliably achieve this using a manual purging system.
It is assumed that a tube leak occurred rapidly and created significant secondary damage, so that upwards of 40 tubes were damaged. From EPRI information (EPRI 2003), the boiler outage time increases steeply as secondary damage increases. It took 11 days to repair the boiler which resulted in 11 days of lost electricity production.
Inspecta APS retrofitting
The Inspecta APS system can be installed into the current Inspecta ASLD configuration by simply replacing the existing Inspecta pipe-set with an Inspecta APS enabled one. All existing plant wiring remains the same.
Installing Inspecta APS onto a boiler ensures the pipe-sets are automatically kept clear of fly ash, ensuring that the sensitivity of the Inspecta steam leak detection system is not compromised. This, in turn, will enable the system to reliably detect small tube leaks at a very early stage.
Benefits of the Inspecta APS
- Complements the existing Inspecta ASLD system.
- Easily retrofitted to Inspecta ASLD plant sensor network. The Binder connector fitted, is compatible with the Inspecta HA-3 sensor. An option exists to fit power station-specific connectors if required.
- Significantly increases the effectiveness of the Inspecta ASLD system by automatically maintaining optimum performance levels.
- Improved early leak detection means that boiler outage times can be significantly reduced.
- Inspecta APS removes the routine maintenance human factor. It is automatic and does not require any human intervention to function.
- The system is purpose-designed to work in the extreme environmental conditions of a power station boiler house.
- AI-driven adaptive performance
If early leak detection is achieved by installing Inspecta APS, and consequently reducing downtime for leak repairs in a large generation unit, by only one day, the savings in electricity production loss exceed the cost of the system by ten-fold.
Contact Instrotech, Phone 010 595-1831, sales@instrotech.co.za , www.instrotech.co.za
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