Waste-to-energy (WtE) facilities have the potential to become one of the most sustainable and reliable forms of energy creation on the planet, but they have their challenges. The most eco-conscious way of adopting WtE is by repurposing fossil fuel plants and retrofitting them for burning and transforming biomass.
Whether working with old or new mechanisms, each scenario requires prioritizing erosion- and corrosion-resistant boilers and peripherals. Chlorine, salts, and other materials are the most concerning red flags. Certain techniques protect against them to extend equipment longevity, reduce costs, and heighten renewable energy’s reputation.
What Corrosion Prevention Provides WtE Plants
Corrosion creep is a sneaky deterrent to WtE performance and dependability. Even if boiler corrosion prevention involves weld metal overlays (WMOs), it does not protect the rest of the plant from residual, corrosive byproducts and reactions. WMOs degrade after a few years of intense use, requiring individual care to prevent further damage.
Therefore, implementing corrosion protection measures ensures peace of mind, increases safety by defending business-critical components like tubes, and bolsters reliability by preventing unintended service disruptions from accumulated fly ash residues. Operators remain protected and productive as they experience fewer leaks, cracks, and accidents with equipment.
These are several prevention strategies that save WtE plants money. Investing in these processes lengthens a machine’s life span by safeguarding against wear and tear. Industries will spend less on spare parts, reactive maintenance, and downtime because critical components are sturdier and operations are more optimized.
The WtE sector is booming because of growing awareness of the climate crisis and how the energy and waste industries have some of the most monumental roles to play in healing the planet. Corrosion-prevention objectives reduce a corporation’s environmental impact. More substantial boilers, heat exchangers, and scrubbers lead to less waste, fewer opportunities for hazardous materials to escape, and more robust sustainability compliance regarding emissions and carbon footprints.
Every factor compounds to create more efficient and lucrative operations. Setting early precedents for choosing suitable boiler materials, instructing operators on the best care practices, and implementing strict oversight and maintenance schedules defend WtE’s position as a top contender in the green energy space. The reputation enhancement leads to more significant funding and regulatory backing for faster adoption.
How to Implement More Corrosion Prevention
If a WtE facility still needs a structured corrosion prevention plan, these are industry-leading techniques to remain competitive. Facility structures are becoming more diverse as WtE innovations arise annually, so trial and error may be necessary to find the perfect combination of solutions.
Choose the Right Materials
Boiler corrosion prevention requires appropriate materials, which makes a world of difference when withstanding the intensity of waste and biomass energy generation. The most popular and well-regarded options include:
- Stainless Steel. Choose austenitic over martensitic steels for their naturally high resistance against corrosion and heat, alongside extensive market incumbency.
- Fiberglass-Reinforced Plastics. This is a lightweight alternative to other materials with comparable corrosion resistance.
- Ceramic. It has high temperature tolerances, and its strength improves with coatings.
- High-Nickel Alloys. These are ideal against acidic elements and chlorides.
- Bricks. Prioritize this in WtE environments dealing with high volumes of acid.
Apply Surface Coatings
As mentioned with ceramic, many materials become more resilient with surface coatings. The WtE industry uses a few methods, including epoxy, ceramic, and thermal sprays. Each has benefits but increases protection against waste in any state of matter.
For example, thermal spraying has gone through significant advancements over the years as it caused high permeability. Experts have reimagined it for modern applications with stronger bond strengths, substrate pretreatments, and heightened spray velocity to make it market-viable. Alternatively, epoxies are easy to apply and have intense adhesion properties.
Perform Chemical Treatments
Sometimes, WtE technology needs more than surface coatings. Chemical treatments are more temporary barriers against corrosion, but they are conveniently integrated into process streams. These are the most common:
- Passivation. Uses oxidizing agents to eliminate contaminants on surfaces to form a protective layer.
- Corrosion Inhibitors. Relies on adsorbent phosphates, nitrites, and more to create shields on material surfaces. There are also inhibitors for scale to prevent deposits.
- pH Management. Adds acids or sodas to slow the corrosion rate when water streams are too alkaline or acidic.
- Biocides. Combats microbial-influenced corrosion and spread by introducing compounds that hinder growth.
Leverage Cathodic Protection Measures
WtE plants may incorporate more electricity to prevent corrosion rather than blending additives into streams. This is called cathodic protection, and it usually takes the form of sacrificial anode, galvanic cathodic, or impressed current protection.
Sacrificial anode cathodic protection relies on having another high-voltage metal alloy like zinc or magnesium as the anode to handle the brunt of the corrosive reaction. This requires more supervision than other methods, primarily when avoiding sags that reduce voltage by up to 90% or spikes causing safety concerns. Galvanic cathodic protection operates similarly but uses differing metals. Finally, impressed current cathodic protection directs a current to the corrosive material through anodes made of elements like graphite. Then, the surface becomes a protected cathode.
Reinforce Maintenance and Waste Management Habits
Strategies only matter if the equipment receives the attention required to operate effectively. Routine inspections and preventive maintenance alert operators of problems early, allowing them to clean and perform healthy waste management of corrosive byproducts.
Where Corrosion Prevention Has Benefitted Plants
Research shows how much boiler corrosion prevention affects shutdown times. Equipment failures are responsible for 22.9 days of unscheduled time and operation losses in WtE plants, with 43% of those pinpointing boilers as the primary cause. Plant managers must focus on current research to find the most impactful ways to direct remediation and process discovery.
How effective have these strategies been in WtE facilities? One case study explored the effectiveness of high-velocity thermal sprays on stainless steel at the Renergia Perlen plant in Switzerland. After 14 months, there was no sign of corrosion or damage to sprayed boilers, extending their life more than outright replacements could—which would happen every five years or less.
Waste-to-Energy Facilities Can Withstand Corrosion
The WtE sector is expanding, and maintaining momentum is crucial for an energy- and waste-cognizant future. Burning and converting waste and biomass into a reliable fuel source means investing in the infrastructure with even more research and development (R&D), and regulatory action. Success is inevitable if plant managers and stakeholders reinforce the value of erosion and corrosion prevention.
—Emily Newton is an industrial journalist who regularly covers stories for the utilities and energy sectors. She is also Editor-in-Chief of Revolutionized.