Maintenance, Test & Measurement, Calibration


Automatic purge system for power stations

February 2023 Maintenance, Test & Measurement, Calibration

The 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 buildup within the Inspecta pipe-sets for leak detection in power stations.

Instrotech designed the successful Acoustic Steam Leak Detection Systems (Inspecta ASLD) and has now developed a fully automatic purging system that is 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 Eskom power stations, Inspecta ASLD systems use acoustic detection technology that detects tube leaks less than 2 mm in diameter in the large boiler structure. The coal used by Eskom 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 manually or automatically cleaned their ability to detect the leaks early is significantly degraded.

Cost savings case study

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.

If the fly ash is allowed to build up over a period of five to six hours, this will result in a serious degradation in the leak detection sensitivity of the Inspecta ASLD. Under these degraded conditions, tube leaks may only be detected after progressing for some time. 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.

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. If there is a delay in the detection of a fast progressing tube leak by just a few hours, the downtime to repair the boiler may increase by more than five times compared to a leak that is detected earlier.

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 tenfold.


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