Increase of operational reliability of turbine components at the Vilyui-2 hydroelectric station

Conclusions

• 1. The collar seal of the turbine shaft is simple, corresponds to manufacturing and assembly requirements, is reliable in operation, and is insensitive to changes in the turbine operating regime.

• 2. The processes of manufacturing runners of Francis turbines at plants require further improvement to ensure minimum residual stresses and casting and welding defects.

• 3. During repair of Francis turbine runners having fatigue cracks, it is necessary to carry out an instrumental check for deformations of the rim and hub. It is necessary to develop simple and reliable instruments for checking deformations of elements during grooving and sealing of the cracks.

• 4. Air-arc cutting, although it is a highly productive method of grooving cracks, without an instrumental check for deformation of the rim (hub) it leads to distortion of the seal gaps and to additional works. Grooving of the cracks by grinding wheels is an effective and sufficiently productive method.

• 5. It is necessary to prepare and publish methodological instructions on eliminating cracks on runner blades of modern turbines with elucidation of the statistical data on operation of runners, with technological repair charts, tools, equipment, mechanization means, etc., being used.