In collaboration with HÜBERS and glass fabric manufacturer Chongqing Polycomp International Corp. (CPIC), Covestro has created the first ever large polyurethane (PU) rotor blade in China.
Manufactured at the Shanghai FRP Research Institute, the blade is 37.5m long and dimensioned for an output of 1.5 megawatts. It is made with a special infusion resin in conjunction with reinforcing glass fibers.
The half-shells for the rotor blades are manufactured using the vacuum infusion process that enables short cycle times. This involves placing the core materials and glass fiber fabrics in a mold and sealing the structure hermetically with a film. Once the vacuum has been created, introducing the liquid resin starts the infusion process.
“This is a clear cost advantage for manufacturers,” said Kim Klausen, who is in charge of Covestro’s global wind energy program. “After all, rotor blades account for around a quarter of the total cost of new wind turbines.”
Thanks to the vacuum, the process only requires a relatively short amount of time and prevents the formation of cavities. The advantage that PU resin has over epoxy resins is that it flows more easily and ensures better wetting of the glass fibers used for reinforcement. The resin also exhibits good mechanical properties.
Curing process starts when the mold is subsequently heated and is faster than when using epoxy resins.
Covestro has also developed an efficient solution for the coating of steel towers and rotor blades. With its Pasquick technology, the number of coats can be reduced compared with the conventional process and it cures faster. Both factors help to further reduce the cycle time and the manufacturing costs of wind turbines.
Source: China Plastic & Rubber Journal
