Design optimization of head cover of vertical francis turbine from maintenance perspective in context to sediment laden river projects

Abstract

Francis turbine operating in sediment laden river projects, excessive wear and damage often occurs on the guide vanes, facing plates, runner and labyrinth rings due to sand erosion. The requirement of dismantling the head cover to repair the facing plates and wearing ring is one of the major influencing parameter of turbine assembly design to increase down time during turbine maintenance. This article discusses on standard assembly design of head cover for vertical Francis turbine installed in Nepalese hydropower station, including its effect on unit outage during overhauling of the machine. Design optimization of head cover has been carried out by considering the maintenance performance analysis tool, intending to explore the ease of maintenance and to identify the maintenance friendly assembly design of vertical Francis turbine.