Coal firing furnace and method of operating a coal-fired furnace

Abstract

A method of operating a pulverized coal-firing furnace so as to achieve no more than a predetermined variation in the instantaneous vertical velocities of the flow exiting a combustion chamber of the furnace is provided. The method includes, in one variation thereof, providing a series of lower compartments for introducing therethrough one of air, fuel, and air and fuel into the combustion chamber. At least one upper compartment is disposed above the topmost compartment of the series of lower compartments at a relative disposition to the topmost compartment in a spacing range between a contiguous disposition to a more spaced disposition which is no more than twice the average spacing between any given compartment and an adjacent compartment. Air is injected from the at least one upper compartment generally in opposition to the swirling fireball along a direction which is offset to the other side of the diagonal in a manner such that the injected air promotes the evolution of the swirling fireball into an upward flow in the top half of the furnace characterized by portions thereof flowing upward at differing vertical velocities with a maximum variation of no more than thirty percent between the instantaneous vertical velocities of the portions of the upward flow as measured across a horizontal plane in the top half of the furnace.