FAILURE ANALYSIS STUDIES ON COMPONENTS• FROM THERMAL POWER PLANTS

Abstract

The thermal power plant is a plant based on boiler - turbine system and using coal / gas as fuel for the generation of steam. It provides most of the world's supply of electricity. It has been estimated that failures of boilers can be considered as one of the most likely causes for failure of thermal power plant. Boiler tubes of coal fired thermal power plants, subjected to prolonged'exposure at elevated temperature and pressure, continue to loose their load bearing capacity due to accumulation of severe damage. The corrosion damages at the inner and outer surfaces of the tubes are responsible for reduction in tube wall thickness. Main corrosion problems in coal fired power plants are the water side corrosion of inner wall tubes of the boiler and the oxidation / sulphidation and hot corrosion of outer walls of boiler tubes. The former is well understood and can be controlled by controlling the chemistry of feed water, the fire side corrosion is little more complicated and is a function of several variables, both operating condition and material. In this investigation efforts have been made to identify the various tubes failures in a. thermal power plant. The required tube samples have been collected from Panki Thermal Power Plant, Kanpur (U.P.). They have been systematically examined by visual inspection, metallography, cross section measurement, identification and characteristic of scale by XRD, SEM and EPMA analysis.