Radiant device with gas burner and recirculation, adapted in view of reduced production of nitrogen oxides

A radiant device with gas burner and recirculation of burned gases for heating a vessel (1) bounded by a wall (10), this device comprising in longitudinal axial direction (L) a section (Se) external to the vessel (1) and a section (Si) both internal to the vessel and divided into three internal subsections (Si1, Si2, Si3) disposed successively at increasing distance from the wall (10) and, in inward radial direction (R), an envelope (2) comprising an external casing (21) and an internal envelope tube (22), the end (220) of which remote from the wall (10) is closed, an exchanger (3) disposed in the envelope (2) and extending over a portion of the external section (Se) and over the first two internal sections (Si1, Si2), a recirculation tube (4) extending over the third internal section (Si3) at a radial distance from the envelope tube (22) and having open inlet (41) and outlet (42) ends respectively relatively close to and relatively far from the wall (10) of the vessel, a retaining tube (5) internal to the exchanger (3) and extending over a portion of the external section (Se) and over the first internal section (Si1), a furnace tube (6) disposed in the exchanger (3), retained by the retaining tube (5) in the extension thereof and extending over the second internal section (Si2), and a central injection tube (7) transporting the gas, extending at least into the retaining tube (5) and traversing a partition (56) separating the retaining tube (5) from the furnace tube (6), the exchanger (3) comprising a separating tube (30) that defines with the retaining tube (5) and the furnace tube (6) an air intake path (T1) starting in an intake inlet (211) drilled in the casing (21) and ending at intake orifices (60) drilled in the furnace tube (6), the separating tube (30) defining with the envelope (2) a smoke-exhaust path (T2) ending at an exhaust outlet (212) drilled in the casing (21), and the furnace tube (6) ending in a nozzle (61) disposed facing the inlet end (41) of the recirculation tube (4), wherein the central injection tube (7) is fed by two conduits (71, 72), the first (71) of which transports at least gas and the second (72) of which transports at least air, in that the central injection tube (7) ends at a burner (8) disposed in the furnace tube (6) and discharging at the level of the nozzle (61), and in that a valve (710, 720) is interposed in at least one (72) of the conduits (71, 72), outside the casing (21).