Power Volume 55, No. 1 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 Excerpt: ...a circular screen to the discharge spout. The air accompanying the coal passes out through a sheet-iron housing and stack. The bottom of this housing is formed by a screw conveyor, into which the pulverized coal drops from the mill discharge. This conveyor brings the coal to an elevator which feeds it into other screw conveyors and distribo es it to the bins located at the furnaces and boilers. When the fuel-preparing plant first started to operate, it was noticed that black clouds of coal dust escaped through the stack that carried off the surplus air from the pulverizing mills. This was overcome by connecting the mill exhaust stack to the suction of the fan that blows the powdered fuel into the drier furnace. This not only eliminated the dust, but effected a noticeable saving in the fuel required for the drier. About 50 cu.ft. per pound of coal is the amount of air required to carry the powdered fuel through the furnace pipe into the furnaces. This is less than one-third the amount required for combustion. The remaining two-thirds enters through adjustable portholes. The waste-heat boilers, built to receive the waste gases from the reverberatory furnaces, absorb from 40 to 50 per cent of the heat in the coal fired. When 93 tons of coal was burned in the furnace per 24 hours, the evaporation in the waste-heat boilers was 4.56 lb. of water per pound of coal, with a steam pressure of 185 lb. gage and a steam temperature of 540 deg. P. In designing the settings of the waste-heat boilers, it was necessary to take into careful consideration the question of ash deposit in the flue. For instance, long horizontal connections, particularly when of small cross-section, gave trouble by accumulating a deposit of fused dust and ashes. This trouble was corrected by usin...