BURNER DEVICE FOR INDIRECT HEATING OF A FURNACE CHAMBER

The subject matter of the invention is a burner device for liquid or gaseous fuels for indirect heating of a furnace chamber, with a burner chamber (12) with a burner chamber orifice (16), with a radiant tube (16) which surrounds the burner chamber (12) at least in the region of the burner chamber orifice (16), and with an inner tube (18) which is arranged in the interior thereof, preferably runs coaxially with respect to the burner chamber orifice (16), and has an inner tube inlet (20) which points towards the burner chamber orifice (16) and an inner tube outlet (22) which is directed towards a closed end (21) of the radiant tube (17), wherein the outer circumferential surface of the inner tube (18) forms, with the inner circumferential surface of the radiant tube (17), an annular gap (23) for returning the gas mixture which flows through the inner tube (18) from its inlet (20) to the inner tube outlet (22), and wherein a recirculation passage (26) is configured between the inner tube inlet (20) and the burner chamber orifice (16). In order to develop a burner device of this type in such a way that a flameless oxidation can be reliably ensured in the interior of the device by a suitably high degree of recirculation of exhaust gases even in the case of the comparatively small dimensions of the radiant tube, the invention proposes that the ratio of the flow cross section (AI) of the inner tube (18) to the flow cross section (AR) of the annular gap (23) is selected in such a way that the static pressure component of the gas mixture flowing through the inner tube (18) and the annular gap (23) is smaller in the region of the inner tube inlet (20) than in the annular gap (23) in the region upstream of the recirculation passage (26). As a result of this solution, the emission values of a radiant tube burner device of this type are as satisfactory as those which are possible in the case of direct heating of a furnace chamber.