BHEL’s new technique to combat silt erosion in Hydro Power Stations.
Two Hydro Electric Power Stations in the country have extended their lifespan by nearly five years by using a new High Velocity Oxy Fuel (HVOF) coating, developed indigenously by Bharat Heavy Electricals Limited (BHEL) to save critical components from silt erosion.
The process was applied successfully at Shanan (Punjab) and Baira Siul (Himachal Pradesh) HEPs. Encouraged by the results in these power stations, Uttaranchal Jal Vidyut Nigam (UJVN) has placed an order for coating the submerged parts of their 4x76 MW Maneri Bhali Hydro Power Station (Stage II).
Silt erosion in hydroelectric power stations and machinery is a worldwide problem and is more acute in India, especially in the Himalayan region. As per a recent study, silt erosion costs Indian hydro power stations Rs.5000 to Rs.6000 million every year due to loss of efficiency, forced outages and repairs.
There is a great potential for development of hydel power in the country, particularly in the Himalayan region. However, components of hydro power stations in this region are prone to severe erosion due to the presence of quartz particles in streams and rivers. Especially during the monsoon, it becomes impossible to control the silt convent passing through the turbine.
To combat this problem, in addition to UJVN, a number of state/central utilities have entrusted BHEL the contracts for application of HVOF coatings on critical components of hydro power stations like guide vanes, labyrinth seals, runner blades, lower rings, and top covers, which are exposed to erosion.
A proposal has also been submitted to the Government through the Central Electricity Authority (CEA), for setting up a national facility for undertaking further research on hard coating of underwater components of hydro turbines.
During fiscal 2004-05, BHEL spent about Rs.125 Crore on R&D, which was the highest among comparable industries in India. The focus of BHEL's R&D programmes is on areas like state-of-the-art control & instrumentation systems; clean coal technologies including Integrated Gasification Combined Cycle (IGCC,",",","); non-conventional energy systems; improved transmission and distribution products and systems; high efficiency, silt resistant hydro turbines and improved transportation systems.