Pulverized-Coal Flames: Flame Propagation in the Absence of Recirculation

摘要

The Bureau of Mines conducted an experimental study of conditions needed to produce flames of pulverized coal when the heat needed for ignition is supplied only from the flame and hot furnace refractory. An electrically heated furnace which burned about 1 pound of coal per hour was designed and fabricated. A sheath of air, surrounding the primary coal and air stream, was used to prevent entry of hot gases from recirculating combustion products. Furnace temperatures needed for ignition ranged from about 1,830F for an Illinois coal to 2,250F for a Beckley seam coal. Apparent flame velocities were about 2 to 5 feet per second, increasing the volatile content of the coal and with distance from the burner mouth to the flame. The time required for ignition, approximately 0.02 to 0.07 sec, was a better measure of flame behavior than was velocity. (Author)