| HRSGs and boilers
Managing corrosion and extending asset life in European WtE boilers
Waste-to-energy boilers operate in environments where corrosion is an inherent and ongoing consideration. The combination of chlorine-rich fuels, variable feedstock composition, and elevated steam conditions accelerates material degradation when compared to that encountered in conventional power generation. For maintenance teams, the focus is on effective corrosion management throughout the asset’s operational life. This requires a clear understanding of degradation mechanisms, supported by appropriate inspection strategies and timely intervention. In this context, material selection and the application of weld overlay, including re-overlay, are established approaches to maintaining component integrity. When implemented correctly, these measures can help manage degradation rates, support planned maintenance strategies, and extend the service life of critical boiler components.
The role of chlorine in high- temperature boiler corrosion In European WtE boilers, chlorine-induced high-temperature corrosion is the primary driver of fireside damage.
Municipal solid waste contains significant amounts of chlorine, largely from PVC and other chlorinated materials. During combustion, chlorine forms hydrogen chloride (HCl) and reacts with alkali and heavy metals such as zinc, lead, sodium, and potassium. These reactions produce low-melting-point
A practical perspective on materials, inspection, and high-quality weld overlay execution Lech Biegus Regional Operations Lead, Integrated Global Services (IGS) metal chlorides, including ZnCl2
and PbCl2
on tube surfaces and ● flux and destabilise protective oxide layers (eg, Cr2
O3 );
● promote active oxidation mechanisms; ● accelerate metal wastage.
In practice, this manifests as general wall thinning, localised pitting, and, in severe cases, rapid loss of tube integrity, particularly in high-temperature regions.
The role of fuel variability Unlike conventional fuels, waste streams are inherently inconsistent. Variations in chlorine content, alkali metals, moisture, and ash composition can significantly alter deposit chemistry. Biomass co-firing, now increasingly common in
Europe, introduces additional potassium and sodium, further influencing deposit melting behaviour. This variability
means that corrosion rates are not constant. A boiler may experience
. These compounds form molten deposits
relatively mild conditions during one run and aggressive degradation in the next. From an operational standpoint, corrosion behaviour in WtE boilers is highly plant- specific and cannot be reliably predicted from design conditions alone.
Understanding erosion–corrosion in WtE boilers
In addition to chemical attack, many WtE boilers experience erosion–corrosion, particularly in areas exposed to high-velocity, particle-laden flue gases. This is commonly observed in: ● superheater banks;
Example of boiler tube degradation. Photo: IGS
www.modernpowersystems.com | October 2026 | 19
Picture credit: Richard OD/
Shutterstock.com
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