Corrosion and Erosion in Pulverized Coal based Fluidized Bed Combustion Boiler in Power Plants

Abstract

Coal is a complex fuel that contains fraction of non combustible minerals called ash and varying amount of sulfur. Since the very early days of using coal for combustion to produce steam for power generation or for processing industries, corrosion and/or erosion problems at high temperatures in pulverized coal/coal based plants have been matters of concern. Up to 450°C, the problem of corrosion can occur at water wall and in range of 500°C to 650°C, this can happen with re-heater and super-heater. The scenario of these issues have been changed in last few years for the reasons which includes use of low grade coal, methods adopted for low NOx emission and demand for higher efficiency. With fluidized bed combustion (FBC), even with low grade coals, higher combustion efficiency could be achieved due to excellent gas/solid reactivity at comparatively low reaction temperature. However corrosion, erosion and combined corrosion/erosion are major causes of degradation of material associated with fluidized bed combustion boilers. This paper describes the investigations carried out on wear due to corrosion and/or erosion occurred in captive thermal power plant using FBC boilers for their steam requirement.