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In wet flue gas desulfurization (FGD) systems, equipment corrosion is influenced not only by the sulfur content but also by halide ions. Halides not only have corrosive properties themselves but can also exacerbate the corrosive environment by altering factors. Additionally, the abrasive effects of particulate matter and high-temperature gas/vapor flows contribute to erosion corrosion, which can damage protective linings.
In practice, corrosion in FGD systems is far more complex, resulting from a combination of different types of corrosion, including pitting, crevice corrosion, stress corrosion, and electrochemical corrosion. This process is gradual and fluctuates over time, influenced by factors such as climate, temperature, and operational conditions. Moreover, the variability in fuel and water composition, as well as equipment and operational differences, affects the corrosion rates of ducts and chimney tubes.
When selecting an appropriate lining material for the steel inner of a chimney, several factors must be considered:
1. Technical Feasibility: The material must meet the corrosion resistance requirements of the complex chemical environment.
2. Economic Viability: The solution should offer a low construction cost, with a focus on reducing upfront investment.
3. Ease of Construction: It should be easy to install, with quick installation speed and a short project timeline.
4. Low Operating and Maintenance Costs: It should be easy to maintain, with a focus on reducing long-term operational costs.
The choice of materials should not only consider initial costs but also the reliable operational life cycle and total service life to make an economically sound decision.
Clad plates are widely considered an economic solution for FGD system chimneys. The most common clad materials used in these applications are nickel-steel clad plate and titanium-clad plates, each offering distinct advantages:
Nickel provide excellent resistance to pitting and stress corrosion cracking, which are common in FGD systems.Nickel-based alloys are particularly effective in handling high-temperature environments and have high strength, making them ideal for use in areas with high mechanical stress, such as chimney ducts and reactor linings.
The most commonly used nickel claddingin FGD systems include C-31, C-625, C-276, and C-59, all of which offer superior resistance to corrosion in the presence of halides and other reactive chemicals.
Titanium alloys, known for their excellent resistance to corrosion in acidic and chloride-rich environments, are ideal for use in FGD systems, where high halide concentrations often accelerate corrosion.
Titanium's high resistance to both general corrosion and localized corrosion, such as crevice and pitting corrosion, makes it a preferred choice for harsh environments.
As a lining material, titanium clad plate can achieve a service life of up to 50 years, ensuring long-term durability in flue gas desulfurization systems.Its low density and high strength-to-weight ratio also make titanium a good option for reducing the weight of structures without compromising performance.
While nickel-steel clad plate and titanium-steel clad plate are still generally more expensive upfront compared with stainless steel, they offer long-term durability and minimal maintenance, resulting in cost savings over the life of the equipment. Using clad materials like nickel-steel clad plate and titanium-steel clad plate in flue gas desulfurization systems provides a cost-effective solution for combating corrosion while maintaining operational efficiency and minimizing maintenance. The selection between these materials depends on the specific chemical, thermal, and mechanical conditions within the system.
Fugo Tech is focused on the manufacturing of clad metal plate and distributes the Stainless Steel, Titanium, Nickel Alloy, Zirconium and other non-ferrous metal pipes, fittings, flanges, and fasteners.
