Fireside Corrosion Monitoring

KEMA employs several corrosion monitoring techniques in industrial boilers including cooled and uncooled expositions probes, KEMCOP’s and electrochemical corrosion monitoring

Corrosion monitoring itself is well established and it is practiced in many ways. Each area of corrosion has its specific monitoring technique.

 

KEMCOP: simple and effective monitoring of corrosion and fouling

In 1997 KEMA started development of the KEMA Corrosion Probe (KEMCOP) which is a patented small sized corrosion probe. The KEMCOP overcomes all of the limitations of the classical corrosion monitoring techniques. The KEMCOP is a relatively cheap corrosion monitoring system that is used to monitor corrosion during operation at different spots in the boiler. The principle of the KEMCOP is based on the integration of a small sized corrosion probe inside the strip of a membrane water wall. The fixation of the probe in strip provides the cooling of the probe. The option to exchange the KEMCOP’s during full load operation adds up to the other advantages of this form of corrosion monitoring.

 

KEMPhase analysis

KEMPhase is a software tool developed to facilitate the interpretation of results obtained by chemical micro analysis. These are obtained by a Scanning Electron Microscope (SEM). KEMPhase is using sample related compounds with a bandwidth of chemical compositions rather than one unique composition. The SEM image can for instance be broadly defined in very general defined ‘compounds’ like iron oxides, alumina silicates, sulphates and phosphates. But also more specific sulphate compounds can be discriminated in the SEM image depending on their oxygen level. The KEMPhase Viewer enables to evaluate the results of the compound recognition process by correlating these with the back scattered electron image and the original mappings of the chemical elements. By using KEMPhase the SEM image and the series of element mapping are upgraded to an understandable visual representation of relevant substances.

 

KEMCOM

For a more detailed corrosion analysis in the field, KEMA utilises an electrochemical corrosion monitor. With this device it is possible to measure corrosion in real time and it provides the possibility to relate the results with a combination of influencing factors. An electrochemical corrosion probe is used for the collection of corrosion data. Cooling air is used to keep the electrodes at a constant surface temperature. Two types of probes are generally applied. One type for use in the water wall area has front face electrodes and is mounted flush with the water wall. The other type is used in the super heater area of the boiler, is inserted deep in the boiler and has ring type electrodes. By using reference rings of each material cut from the same tube as the exposed ring, it is possible to determine the material loss within an accuracy of 4 micron. A minimal exposure period of 3 weeks should be applied to get sensible results.