Application of hydro-abrasive erosion model from IEC 62364:2019 standard in Francis turbines

Abstract

Hydro-abrasive erosion in hydraulic turbines is critical and one of the prominent issue due to its association with maintenance costs and production losses in the hydropower plant. IEC 62364:2019* standard guide focuses mainly on hydroelectric powerplant equipment and provides the standard on particle abrasion rates on several combinations like operating conditions, component materials properties, water quality among many factors. With the consideration of different critical parameters, a theoretical model of abrasion rate on hydraulic turbines is proposed by IEC 62364:2019. Present study is conducted to elucidate the several terms used in the theoretical model of abrasion rate for Francis turbine as per the guidelines. The work has taken account into run-off river (RoR) hydropower plant consisting of Francis runner operating in sediment laden rivers in the Himalayan area. Theoretical expected erosion depth for runner inlet, runner outlet, guide vanes facing plates and labyrinth seals is calculated. Characteristic velocities of runner (Wrun) and guide vanes (Wgv) were estimated to be 32.26 m/s and 35.05 m/s respectively. Particle load was calculated based upon the sampling data available from the site. Measurement data from field observation during overhauling was used for comparison with the data calculated from empirical relation. For 229 hours operation of turbine, observed abrasion depth varies from 8.1 mm in guide vanes to 1.5 mm in labyrinth ring corresponding to calculated values of 7.53 mm and 1.89 mm for same components. Results shows good correlation among calculated values from IEC and measured values from the site. An optimized solution can thus be devised based on the evaluation of hydro-abrasive erosion along with energy production and maintenance expenses.