The operational challenges of biomass-fuelled Circulating Fluidized Bed (CFB) boilers present complex materials engineering problems, particularly in managing simultaneous corrosion and erosion mechanisms. This case study examines a targeted tube protection strategy implemented at a waste to energy power generation facility.
Initial Diagnostic Assessment
Commissioned in 2008, the CFB boiler rapidly experienced critical tube metal degradation. Preliminary investigations identified two primary degradation pathways: erosive wear from particulate matter in waste-derived fuel streams and chemical corrosion induced by high-temperature gaseous elements.
The initial protective cladding quickly revealed limitations, with accelerated tube wall thickness reduction threatening the infrastructure's long-term operational integrity.
Critical observations included:
- Rapid material loss rates
- Non-uniform wear patterns
- Potential for premature structural compromise
Materials Engineering Solution
The solution chosen was SMARTGardTM; a maintenance philosophy that includes HVTS® (High Velocity Thermal Spray) cladding, engineered to protect CFB boilers from fly ash erosion, fireside corrosion, and fouling.
Integrated Global Services (IGS) applied the cladding system, customised to the process to mitigate the wastage and extend the life of the boiler tubes. To maximise budget utilisation during past outages, a thinner specification cladding was installed in 2015, focusing on the critical areas and ensuring boiler reliability until the 2017 outage.
Performance Validation Methodology: Inspection in 2017
The inspection was carried out together with the third party CFB boiler expert and the plant manager. The cladding was observed to be in excellent condition. This mini outage verified the reliability of the IGS HVTS® cladding. An extensive inspection was completed throughout the entirety of the cladding scope. With the topcoat completely intact, the cladding system was confirmed to be in ‘as-applied’ condition.
Fouling was virtually eliminated in the cladded locations and any adhered fouling was no longer tenacious and was easily brushed away.
Maintenance Implementation Timeline
- 2008 – 3rd party commodity thermal spray coating installed to mitigate expected corrosion within the CFB Boiler.
- 2015 – Aggressive corrosion-erosion mechanism analysed and customised IGS SMARTGardTM HVTS® cladding solution installed
- 2018 – 5-year maintenance plan created, prioritising locations based on wastage rates and tube condition.
Technical Considerations
The HVTS® cladding solution demanded a multifaceted engineering approach. Critical design parameters included:
- Maximising protective layer adhesion
- Eliminating thermal stress
- Developing a long-term protective system and ensuring boiler reliability
- Ensuring compatibility with existing boiler infrastructure
Quantitative Outcome Analysis
The implemented cladding protection strategy demonstrated significant operational advantages including the prevention of large-scale tube panel replacement, reduced maintenance frequency, and optimised outage duration, preventing any unplanned production interruptions.
Operational Economic Considerations
The plant manager commented: "We needed to protect a large area and prevent extensive panel replacements. With outage costs running into tens or hundreds of thousands of dollars daily, the maintenance expenses were minimal compared to potential production losses. Our goal was to reduce annual outage time to under 10 days, which meant we had to be incredibly strategic about addressing critical areas efficiently."
Methodological Insights
The successful intervention underscored several critical engineering principles:
- Comprehensive initial diagnostic capabilities
- Customised material engineering solutions
- Data-driven maintenance approach
- Predictive wear modelling strategies
Conclusion
Advanced cladding technologies provide a sophisticated intervention for mitigating material degradation in boilers, particularly in challenging combustion environments with complex fuel streams.
The research suggests continued development of predictive wear modelling and adaptive cladding technologies could further enhance long-term infrastructure reliability in waste-to-energy and biomass boiler applications. The case study demonstrates the critical role of innovative materials engineering in extending operational infrastructure lifespans and optimising industrial maintenance strategies.
By integrating comprehensive diagnostic approaches, precise engineering interventions, and systematic performance monitoring, plants can transform potential operational vulnerabilities into sustainable, reliable infrastructure solutions.
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