Abstract: A method of firing a pulverized fuel-fired steam generator furnace wherein a mixture of recirculated cleaned flue gas and air is supplied to the mill for drying the pulverized fuel in the mill and transporting the pulverized fuel to the furnace. The volume flow rate of the gaseous mixture of recirculated flue gas and air is controlled in response to the feed rate of fuel to the mill to maintain a mixture to fuel ratio in the transport stream of about but not less than 1.5. The volume flow rate of recirculated flue gas with respect to the volume flow rate of air is controlled to maintain the oxygen content of the gaseous mixture at a level of at least 12% by volume and preferably in the range of 12 to 15% by volume.

Abstract: A tangentially fired pulverized coal furnace in which the means for introducing fuel and air from the corners operate as independent firing systems at low ratings and contribute to the fireball at higher ratings. The coal flow through a nozzle is deflected radially outwardly at low ratings and allowed to continue essentially straight at high ratings. A surrounding secondary air flow is concentrated at the coal stream and may be varied from a swirling action at low ratings to a parallel flow action at high ratings.