Patent ID: 7624707
Filing Date: 2009-12-01
Classification: F23L

Abstract:
1. An over fire air port arrangement for a fossil fuel fired furnace or boiler, comprising: front and rear walls and a pair of sidewalls forming a furnace enclosure; vertically spaced bottom, second and third level burners through at least one of the front and rear walls generating bottom, second and third flame paths, respectively, in the furnace enclosure when burning fossil fuel; and an over fire air port arrangement configured to efficiently reduce fuel NOx formation during combustion in the furnace enclosure, the over fire air port arrangement including at least one bottom over fire air port through at least one sidewall appropriately sized and positioned to transversely and directly inject over fire air into the bottom flame path to provide sufficient residence time and mixing of the over fire air in the bottom flame path without interfering with the other flame paths; and at least one middle over fire air port through at least one sidewall, spaced vertically above and horizontally offset from the at least one bottom over fire air port and appropriately sized and positioned to transversely inject over fire air into at least one of the second and third level flame paths to provide sufficient residence time and mixing of the over fire air in the at least one of the second and third level flame paths without interfering with the other flame paths.