by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

According to Statista, installed wind power worldwide reached a cumulative capacity of almost 743 GW (gigawatts) in 2020 and is expected to reach almost 841 GW by 2022. As it remains a competitive source of renewable energy, engineers are looking for ways to enhance the efficiency and reliability of wind farms and the turbines that comprise them. One design aspect under consideration is the seals that are used in these turbines. This week, we will discuss the various benefits of spring-energized seals for wind turbines. 

Sealing Challenges in Wind Energy

Wind turbine seals face many challenges during their lifetime:

  • Wide range of temperatures and temperature variations
  • Abrasive materials that can wear down a seal jacket and damage the sealing surface over time
  • Complications arising from below freezing temperatures
  • Regular exposure to moisture and rain
  • Constant exposure to UV that can degrade the seal jacket material

In addition, there are issues related to seal failure: maintenance and repair, a potential domino-effect of damage to internal components (e..g, gear box, electronics),efficiency errors, downtime, and technician safety.

One potential sealing solution for wind energy applications is the spring-energized seal. Spring-energized seals are commonly used in renewable and green energy applications, and wind energy is no exception.

What Are Spring-Energized Seals

Unlike traditional seals, spring-energized seals have an energizer (usually in the form of a spring or rubber) that enables the seal lip to maintain contact with the sealing surface. As with traditional lip seals, they are available in a wide variety of configurations. And there are different types of spring energizers to choose from, allowing for a fairly customized sealing solution for various renewable energy applications.

Benefits of Spring-Energized Seals

The resiliency made possible by the energizing spring enables the seals to provide very reliable performance in high pressures as well as wide environmental pressure variations. In fact, when configured correctly they provide an almost leak-proof seal, which can be critical not just for the wind turbine as a whole but for the precision components inside. 

Spring-energized seals can continue to provide an effective seal even in cases of hardware misalignment, out of rounders, eccentricity, and some degree of jacket wear and changes in sealing surface condition due to wear  (often caused by abrasive materials in the environment). They can also account for dimensional changes that result from wide temperature differentials such as those experienced by wind turbines, as well as extreme heat and cryogenic environmental conditions that can range between 140°F and -65°F.

Implementing spring-energized seals results in several benefits. More reliable seals reduce overall maintenance requirements for a wind turbine, and this can have a very positive financial impact for wind farms with multiple wind turbines at work. Effective, durable seals also lead to significantly less downtime and associated costs as well as more continuous electricity output. In fact, investing in spring-energized seals as opposed to more traditional seals will undoubtedly save money over time and extend the useful life of the wind turbines.

When a polymer material such as PTFE, PEEK, and UHMW PE is used for the seal jacket, there are no complications due to lubricants because these materials are self-lubricating. They have extremely low friction, do not exhibit stick-slip behavior, and have an extremely low starting torque and prevent the seal from freezing to the sealing surface. In addition, PTFE and PEEK exhibit excellent chemical compatibility with the various lubricants they may come into contact with. 

They also possess good UV resistance, which can be critical for seals that are constantly exposed to sunlight. Because wind turbines are often exposed to abrasive materials such as sand, dust, and saltwater, their wear properties are a definite benefit. The low levels of moisture absorption exhibited by these materials means that they will not change shape when exposed to humidity, moisture, and water.

Both materials also work well in the presence of extreme temperatures (including cryogenic) and exposure to moisture, humidity, and rain. In addition, PTFE and PEEK are available in high PV (Pressure-Velocity) grades that are ideal for dynamic sealing solutions. When combined with the proven performance of a spring-energized seal, they lead to more efficient wind turbines.

Finally, the use of spring-energized seals also has a positive effect on technicians’ safety by reducing the maintenance and repairs that must be performed at dangerous heights.

Conclusion

The use of spring-energized seals for wind energy should be considered as an option to 

increase efficiency and useful life while reducing downtime and maintenance costs. These seals along with a polymer jacket can provide an almost leak-proof solution that can withstand the many challenges of seals in the aggressive environments where wind turbines are found.

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