Assessment of Failure Modes of Components in High Capacity Pumps due to Synergistic Effects of Erosion and Corrosion – A Case Study in Lignite Mines

Abstract

Neyveli Lignite Corporation Ltd., Neyveli (a Navaratna Public Sector of Government of India), Tamil Nadu, India, operates three open cast lignite mines of total capacity 24 million tones per annum (mtpa) with ‘three pit head power stations’ of capacity 2490MW. The Mine operations are influenced by the aquifers and high monsoon that necessitated huge pumping of water before excavation of lignite. Hence a network of system of pumping was established for both ground water control (GWC) and storm water Control (SWC). As the volume of water to be handled is high capacity mining pumps of capacity 1.5m3/s and 180m Head are operated. These pumps in most of the occasions handle acidic water pH less than 3.5 and sand particles loaded up to 15% and experience variety of failures including erosion corrosion problems. The ‘Mean Time Between Failures’ was less than 100 hours in Mine-I and replacement and reconditioning of units are challenging jobs for maintenance crew.