Sediment Impact On Turbine Material: Case Study Of Modi River, Nepal

Abstract

Hydropower is considered as one of the most economical and stable base energy source compared with other sources of energy of Nepal. Researches coherent to this field are not new but yet it is not sufficient, lots of tiles have to be kept for better understanding of hydropower effecting elements. Sand is the most affecting element that damages the turbine blades, so research on relation of sand and turbine is most. This research is done to find out the impact of sediment on turbine material. Modi River sediment at eight different stations has been taken as sample and its erosion rate in turbine blade sample specimen has been accounted in this study. Rotating disc apparatus has been utilized to find out the total impact of sand on turbine material. Four same kind of test turbine material is used on single rotating disc all at a time at same condition to define sand impact. Thirty gram (gm) of sediment mixed with three liters of water is used to strike sample pieces for five minutes. Two different tests of sediment samples of 8 different locations were studied. After all the test it is observed that the first test sand sample of location 1 and turbine material 1 has the highest impact with a weight loss of 7.764 mg and least impact in sand sample location 1 and sand sample 3 with a weight loss of 3.5 mg. Average weight loss of turbine material in first location is 5.929 mg which is the greatest impact and 4.0083 at eight locations which is the least. Relating to turbine material first rotating disc turbine specimen P0A has been affected highly with weight loss of 9.289 mg and less eroded on P5A rotating turbine specimen with weight loss of 1.2 mg.

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

“…The underwater components such as guide vanes, runner, facing plate and wearing ring are most affected in run off river projects causing forced outage. 5 Studies have shown that up to 80% of hydro turbines required for future installations under Himalayan basin in Nepal will need Francis type of turbine. 6 Most of Francis turbine installed in Nepalese hydropower stations need frequent overhauling for maintenance and repair of eroded parts.…”

Numerical Analysis of Erosive Wear on the Guide Vanes of a Francis Turbine

“…It has been observed that the shape of runner blade has a significant effect on velocity distribution and hence on the sediment erosion of the runner. Poudel et al [5] studied the impact of sediment on turbine material. They used a rotating disc apparatus to find out the total impact of sand on turbine material.…”

Comparative study of sediment erosion on alternative designs of Francis runner blade

“…Some studies have also been carried out to investigate the effect of size and concentration of silt particles on Pelton turbine buckets through laboratory experiments [8,9]. Some of the earlier researches were focused on the impact of sediment particles on turbine materials [11][12][13][14][15][16][17], and to identify coating materials to protect the surface of the turbine components exposed to sediments [11][12][13][14]. Researches have also been carried out for complete mechanical design of turbines by selection of different erosion resistant materials and coatings [18,19].…”