A waste-to-energy plant in Turin, Italy, was preparing for an outage on one of their lines. The plant required Notified Body (NB) approval for the scheduled work but as the outage was nearing the approval was yet to come. Fortunately, an alternative solution was offered that would deliver the better value and wouldn’t require NB approval.

Power Plant

Corrosion of the Boiler Pressure Parts

The plant, built by CNIM, was commissioned in 2014. Following several years in operation, the operators identified corrosion in the second pass of the boiler. Alloy 625 weld overlay was already installed in the top of the first and second pass, with refractory covering from the grate to the collector at top of 1^st/2^nd pass division wall. After the collector in the second pass, the waterwall had no fireside protection.

Boiler schematic showing the area with highest tube thinning

Selecting a Suitable Solution

The IGS HVTS solution was selected by the operator for a number of reasons. IGS have strong global references in similar applications supported thorough extensive laboratory testing. In addition, though IGS HVTS installs a high nobility, corrosion resistant metallic barrier on to the substrate surface, it is not a welding process, it does not create Heat Affected Zones (HAZ), there is no risk of thermal distortion and it does not require the same approvals as a weld overlay process. Therefore, the planned outage could proceed without any potential delays caused by the requirements of the NB.

HVTS Application in 2019

IGS Europe applied the IGS HVTS alloy cladding system on to a 159 square meter area below the existing alloy 625 overlay to cover the four walls including the division wall. Cyril Narjoz, IGS Boiler Maintenance Subject Matter Expert, said: “The project was well executed with a good synchronization with the client.”

Inspection in 2020 and Unexpected Scope

“One year later, in September 2020, we came back to perform an inspection. The IGS HVTS cladding was in good shape, but the client was worried about the pendant screens in the same area, not protected with HVTS and already replaced”, said Cyril.

In the second pass, this boiler has hanging evaporator panels, that increase the surface exchange area for the temperature transfer. The plant had already replaced them a few years before, and now noticed some signs of degradation, which were confirmed with UT readings performed by IGS. The plant then asked IGS to urgently protect these hanging panels as an unexpected scope. “Fortunately, we were performing another job nearby, and were able to mobilize very quickly”, added Cyril.

The new scope was executed without any problems. Additionally, HVTS cladding was applied to the supply tubes coming from the roof of the boiler that feed the collectors.

Inspection in 2021

Throughout 2020 the plant performed no repairs and had no tube leaks in the zones protected by the IGS HVTS cladding. At the end of 2021 another inspection of the protected area was performed during the application of an additional 50 square meter scope extension on the division wall. Minor touch up areas were addressed in-situ, with no concerns for the boiler pressure part integrity.

IGS HVTS inspection

2021 and beyond

Following the successful implementation and monitoring of the IGS HVTS cladding in the boiler to protect the water walls and pressure parts from metal wastage, the plant established a preventative maintenance program.  On this basis, the client has extended their outage/maintenance interval from approx. twelve (12) to eighteen (18) months, so following the September 2021 inspection the boiler will run through to January 2023 before another planned outage.  This brings significant value to the client by increasing the uptime and availability of the operation of the plant.

Boiler Reliability Guaranteed

IGS leverages decades of experience with over 500 boiler reliability applications. They are at the forefront of maximizing run time while minimizing outage frequency and cost. IGS solution has been successfully implemented to provide scalable, proactively manageable and fully refurbishable boiler tube protection from fly ash erosion and fireside corrosion.

IGS delivers a SMART solution that guarantees boiler reliability

• Systematic Approach to Boiler Reliability
• Materials and Equipment Engineered for Specific Results
• Applications by Trained and Certified Teams
• Results are Measured, Documented, and Monitored
• Testimonials Prove Performance!

 For more information, visit: integratedglobal.com/services/boiler-maintenance/

Integrated Global Services are bronze sponsors of Energy from Waste 2022 where Colin Bateman, Director of Business Development EMEA will be leading a session on 'Managing the technical challenges of changing feedstock - how do plants maintain availability and cope with differing grades and qualities of feedstock supplies?'

For the full programme visit efwconference.com