Patent ID: 6220188
Filing Date: 2001-04-24
Classification: F23C

Abstract:
A windbox burner comprising a register casing (2) with ports (3) for inflow of combustion air, a secondary air pipe (35) coaxial with the register casing and enclosed by the register casing and having inlet ports (36) for secondary air, and a ring damper (20) substantially coaxial with the register casing and extending axially between two first annular sealing means, one of said first annular sealing means being located adjacent to each axial end of the ports of the register casing, said ring damper being axially displaceable and having at each end a second annular sealing means (21;26) which, in the closed position of the ring damper, sealingly abuts a corresponding one of said first annular sealing means (22;23), thereby preventing the combustion air from flowing through the ports of the register casing (3) to the burner tip, said first and second sealing means (21,23;22,26) being made of a stainless and heat-resistant material, and at least one of the first and second sealing means comprising at least one plane leaf spring (23;26) the plane of which is substantially perpendicular to the longitudinal axis of the ring damper (20),wherein the secondary air pipe (35) supports an axially adjustable tubular damper (37) adapted to overlap at least a portion of each of the inlet ports (36) of the secondary air pipe, said tubular damper having an external collar (38) extending, in a first open position of the ring damper, at least most of the distance from the tubular damper to the register casing and substantially closing off an annular passageway between the secondary air pipe and the register casing so that in said first open position, the flow of air through the space between the secondary air pipe and the register casing is substantially blocked by the external collar, and in a second, more open position, the external collar is axially spaced from the ring damper so that an axial opening is present between the ring damper and the external collar, whereby air is permitted to flow through said opening as tertiary air.