The pulverizer shownin Fig:1 has grinding elements consisting of stationary rollers and apower-driven bowl in which pulverization takes place as the coalpasses between the sides of the bowl and the rollers. A primary airfan draws a stream of heated air though the mill,carrying the fineparticles of coal into a two-stage classifier located on the top ofthe pulverizer. The vanes of the classifier return the coarseparticles of coal through the center cone to the bowl for furthergrinding, while the coal that has been pulverized to the desiredfineness passes out of the mill, through the fan, and into the burnerlines. The automatic control changes the supply of coal to the bowlof the mill by adiusting the feeder speed and the flow of primary airby regulating a damper in the line from the pulverizer to the fan.This arrangement of primary air fan has the advantage of having acleaner facility because the mill is under suction rather than beingpressurized, thereby eliminating coal leakage. However, the fan nowmust handle a coal-air mixture and, therefore, its design mustincorporate additional preventivewear features to offset the erosioncaused by the coal-air mixture.

Pulverized coal may be radilytransported through a pipe by means of a high-velocity stream of air,but the coal will not be equally distributed through the crosssection of the pipe. This causes difficulty when two burners aresupplied from one pulverizer mill.the distributor (Fig.2) divides thecross section of the main pipe into several narrow strips. Themixture of pulverized coal and air that enters these strips isdirected into the two burner pipes in order to obtain equal amountsof coal to the burners.