Low excess air tangential firing system

摘要

A furnace (10) in which pulverized coal is burned in suspension. The coal is introduced along with primary air, tangent to an imaginary circle (42). The auxiliary air is introduced tangent to an imaginary circle (44) directly above the primary air, in a direction of rotation opposite that of the primary air. The auxiliary air is directed tangent to a circle of greater diameter than that of the primary air. There are a plurality of alternating levels within the furnace where primary air (38), and then auxiliary air (40), is introduced.