A Study on 500 MW Coal Fired Boiler Unit’s Bowl Mill Performance through Coal Sampling and Characterization: CPRI’s Experience

Coal-fired thermal power stations presently account for nearly 52 % of the total power generation in India’s power generation sector. There is a constant need to monitor the performance of the coal-fired power plant auxiliaries/ components and ensure maintenance of these to optimum levels of operating parameters to achieve the trouble-free generation of quality and consistent electric power output. Coal’s mineralogical content and its physical parameters decide the performance of the coal pulverizer in terms of optimum ground coal output and the life of the grinding elements in the coal mills/ pulverizers. The grinding media in the pulverizes are subjected to high erosion rates owing to the presence of abrasive minerals like pyrites, alumino-silicates and hard minerals like α quartz, which are attached to the coal mass as contaminants during mining. A study was undertaken along with the Pulverizers Division of M/s. BHEL for evaluation of Coal Bowl Mill, for guaranteed performance at a 500 MW capacity NTPC thermal power plant. The study was conducted to assess the effective performance of the pulverizers of this 500 MW boiler unit for its maximum capacity of 60.9 t/hr for guaranteed coal condition and assess optimum output in terms of fineness of the crushed coal during continuous loading under the designed operating parameters. The study was also carried out to ensure that the pulverizer grinding efficiency and the effective output of the finely crushed coal were achieved by proper optimization of the mill mechanical auxillaries and their operating parameters.