ASSESSING THE IMPACT OF SPECIFIC WEIGHT OF DIFFERENT-SIZED PARTICLES ON OPERATIONAL PERFORMANCE OF COAL PREPARATION PLANT

Abstract

In case of firing pulverized coal in power steam boiler certain fuel preparation process has to be taken in order to ensure stable and optimal combustion in boil-er furnace. Before entering furnace low caloric coal is introduced from coal bun-ker to the coal preparation system where milling/pulverization and drying pro-cesses of raw large coal particles are conducted. For the purpose of defining fineness of grinding of pulverized coal mill gaseous mixture at mill outlet is in-troduced to the separator where large coal particles, separated from outgoing mill gaseous mixture, are recirculated to mill for regrinding. In this paper char-acter of two-phase flow in inertial separator at milling plant in TPP Nikola Tesla Unit B under various operating conditions has been analyzed. The CFD ap-proach has been used for calculating two-phase flow in separators flow domain. Measurement data taken on site along with results of performed heat balance calculations of milling plant have been used for validating calculation model as well as for setting appropriate boundary conditions in CFD model. The CFD cal-culations has been performed for different positions of all regulating flaps, recir-culation rates of gaseous phase and values of specific weight of solid phase in two-phase mixture. For evaluating separators operating performance at different operating regimes changes of milling capacity and fineness of grinding of pulver-ized coal at separators outlet have been observed. Additionally, deviation rate of trajectories of different-sized particles to the streamlines of gaseous phase has been examined.