Itaipu Binacional Hydro Power Plant Thrust Bearing Design Optimization for Higher Efficiency

Hydro generators installed in Itaipu Binacional power plant with 824/737 MVA rated output power (50/60 Hz) belong to the largest ones in the world. Among many unique features, the generators are equipped with the largest hydrodynamic thrust bearings ever built (external diameter 5,200 mm, axial load equals approximately 3,600 t). This paper is an attempt to propose a new thrust bearing design with the use of the state-of-the-art technologies and simulation techniques that demonstrate a reduction of friction power losses generated by the thrust bearing. This paper is divided into two parts. Within the first one, the original thrust bearing design which was implemented in the generators is described. Related calculation results based on a TEHD (thermo-elasto-hydrodynamic) calculation software used by Alstom will be presented. A comparison between measurement results gathered in the 1980s is given. In the second part, a potential solution of a more beneficial bearing design is described. The proposed thrust bearing design modification is an implementation of Alstom's Polypad TM coating. This modern polymer (PEEK) coating material has already been used by Alstom in projects around the world for many years. This coating allows pushing the operating parameters limits toward higher temperatures and lower oil film thicknesses far beyond the limits known for the conventional bearing materials.