Waste burner overfire draft system

Abstract

An overfire draft system for a waste burner is disclosed. Such system comprises air vents arranged circumferentially around the base of the burner for communicating the interior of the burner to the atmosphere and a draft modulated damper plate located in each air vent for automatically regulating the volume of overfire air delivered to the interior of the burner. Each draft modulated damper plate is provided with a lower lip which is deflected by a predetermined angle with respect to the plate to create an aerodynamic lift effect with large opening moment to assist the damper plate in its response under low air velocity conditions, and an oppositely deflected upper lip with proportionately less bent surface to avoid flutter or hunting of the damper as it approaches the maximum open position and to provide added dynamic opening force. The overfire draft system is also provided with ducts connected to the air vents and oriented so as to direct air tangentially around the base of the burner and toward the lower inside wall of the burner so as to minimize the disturbance of the inside air. The waste burner may also be provided with draft modulated or forced air vents arranged circumferentially at mid-elevation around the burner and duct means connected to such vents and directed at a small angle with the radius of the burner so as to cause turbulence in the flame zone and reduce the vertical velocity of gases above the fire, thus reducing emission of particulate materials. The waste burner may further be provided with a lip portion secured to the upper end thereof and extending toward the center of the burner for trapping the heavy particles entrained by hot gases and concentrated around the outside perimeter of the burner by the centrifugal forces generated by the usual rotational motion of such hot gases.

Dependencies are inferred from the claim text.