Steam turbines are essential in power generation, converting heat into mechanical energy with impressive efficiency. However, with their performance comes the significant challenge of water droplet erosion. This issue is particularly true for the last, or L-0, stage blades where water droplets impact the leading edge, causing various complications in critical areas. Explore the Kennametal Stellite™ solution for extending the life of steam turbine blades suffering from water droplet erosion.
Enhancing Steam Turbine Reliability and Blade Life with Erosion Shields
Understanding the Severity of Water Droplet Erosion
Water droplet erosion occurs when turbine blades travelling at extreme high speeds strike water droplets, eroding the blade material and creating several critical problems. One major concern is that as material is lost, the natural frequencies of the blades can shift into resonance, resulting in high cycle fatigue failure that can pose serious risks to the turbine’s operation. Additionally, water droplet erosion causes the edges of the blades to become jagged, increasing their susceptibility to crack propagation. If these cracks go undetected, they can lead to catastrophic failures and prolonged outages, which would significantly disrupt energy production.
The Role of Stellite alloy 6B Erosion Shields
To combat the detrimental effects of water droplet erosion, power plants have long used erosion shields to protect the blade’s leading edge. These protective barriers are designed to enhance the durability of turbine blades, ensuring longer service life and improved reliability. With Kennametal's Stellite 6B shields we strive to maximize the performance and purpose of steam turbines using the known wear-resistant properties of Stellite 6B.
Stellite 6B Erosion Shields
Introducing Stellite 6B
A leading material for erosion shields is Kennametal's Stellite 6B (UNS R30016, AMS 5894). Known for its excellent physical and mechanical properties, Stellite 6B is a wrought alloy that offers both superior toughness and exceptional resistance to erosive wear. Its forged microstructure enables it to withstand harsh conditions, making it ideal for turbine applications.
Key Benefits of Stellite 6B
- Enhanced Toughness: Stellite 6B provides the toughness and wear resistance needed to handle the impact from water droplets, ensuring maximum blade life.
- Weldability: Stellite 6B can be easily welded or brazed to turbine blades, facilitating efficient installation.
- Proven Performance: Some operators have had Stellite 6B shielded blades in service for over 30 years, demonstrating their significant advantage.
Types of Erosion Shields
Kennametal offers Stellite 6B erosion shields with a range of profiles and designs to ensure a proper fit to your turbine blade. Two of our primary erosion shield designs include J-style and bar-style. Each design has distinct features that cater to different needs and blade geometries.
J-Style Shields
J-style shields are thinner and are typically brazed to the blade’s leading edge. A precise “J” profile is formed into the shield allowing for exact fit with the blade. Kennametal offers a range of “J” profiles to match your blade geometry.
Bar-Style Shields
In contrast, bar-style shields are larger and machined to fit specific blade designs. These shields are typically welded to the blade. Kennametal produces these shields according to your requirements.
Summary
The threat of water droplet erosion to steam turbine blades is a significant concern that can lead to costly failures and downtime, but Kennametal's Stellite 6B erosion shields offer an effective solution to enhance blade durability. By improving erosion resistance and reducing the risk of crack propagation, these shields help maintain the efficiency and reliability of steam turbines. In turn, investing in erosion shields not only extends the lifespan of turbine blades but also contributes to the overall efficiency of energy production by protecting these critical components to ensure a steady and reliable power supply.
