A dry low NO.sub.X staged combustion system includes a fuel nozzle and a combustion compartment. The fuel nozzle includes a purge gas tube, a diffusion combustion fuel tube, an isolation gas tube, a premixed combustion fuel tube, a premixed combustion air tube. The purge gas tube is configured to feed a purge gas. The diffusion combustion fuel tube is fitted over the purge gas tube, and having an end provided with a diffusion combustion fuel swirler. The isolation gas tube is fitted over the diffusion combustion fuel tube. The premixed combustion fuel tube is fitted over the isolation gas tube. The premixed combustion air tube is fitted over the premixed combustion fuel tube. The combustion compartment is located downstream of the fuel nozzle.

A gaseous fuel-air burner having a bluff body flame stabilizer, and methods of operating the same, are described herein. One device includes a bluff body configured to stabilize a flame produced by the gaseous fuel-air burner, wherein the bluff body has a conical shape configured to stabilize the flame by generating a recirculation zone having a stagnation point where the flame is stabilized.

A mobile heating device operated with liquid fuel is provided, having: a combustion chamber (2) comprising a combustion air inlet (3), wherein the combustion chamber adjacent to the combustion air inlet (3) comprises a widening portion (20) the cross-section of which widens with increasing distance from the combustion air inlet (3) and in which in operation combustion air and fuel are converted in a flaming combustion; a fuel supply which is arranged such that fuel is supplied into the widening portion (20); and an air guide device (6) being adapted to feed combustion air into the widening portion (20) with a flow component directed in the circumferential direction such that an axial recirculation region (RB) forms in the widening portion (20) in which gases flow in the direction towards the combustion air inlet (3) oppositely to a main flow direction (H). The combustion chamber (2) is fluidically sectioned into a primary combustion zone (PZ) and a secondary combustion zone (SZ). The primary combustion zone (PZ) comprises the widening portion (20) and the recirculation region (RB). The secondary combustion zone (SZ) is provided with a secondary combustion air inlet (23) in such a manner that a higher air-fuel ratio λ than in the primary combustion zone (PZ) forms in the secondary combustion zone (SZ).

A device for the post-combustion of exhaust air, comprises a burner, which has a fuel nozzle, and a burner cone and which protrudes in a raw-gas chamber, into an exhaust-air flow of exhaust air to be treated at least by the burner cone of the burner. The burner cone has a one- or a multi-part wall, which wall surrounds the pre-mixing chamber and has one or more wall segments. The fuel nozzle comprises an opening of at least one fuel outlet for discharging fuel into the pre-mixing chamber. The wall bounding the pre-mixing chamber outwardly on the lateral side has a structure such that the pre-mixing chamber formed in the interior of the wall opens in the downward direction in the manner of a funnel on at least one cone longitudinal segment symmetrically to an axis of symmetry defining the axial direction of the burner. The burner cone comprises, in at least one longitudinal segment of the cone longitudinal segment of the wall, which cone longitudinal segment opens in the manner of a funnel, a plurality of tangential inlet openings in order for exhaust air surrounding the burner cone to enter the pre-mixing chamber tangentially.

Embodiments of the present invention include high-temperature staged recirculating burners and radiant tube burner assemblies that provide high efficiency, low NOx and CO emissions, and uniform temperature characteristics. One such staged recirculating burner includes a combustion tube having inside and outside helical fins forming opposing spiral pathways for combustion gases and products of combustion, a combustion nozzle coupled to the combustion tube, a gas tube running axially into the combustion tube, and a staging gas nozzle coupled to the gas tube, where the staging gas nozzle includes radial exit holes into the combustion tube and an axial gas staging tube extending into the combustion nozzle to stage combustion.

A burner apparatus and method which provide an increased amount of internal flue recirculation for reducing NO.sub.x emissions by ejecting a series of surrounding primary fuel streams and also ejecting on one or more subsequent series of surrounding fuel streams outside of the burner wall toward the burner combustion wherein each succeeding series of surrounding fuel streams must travel a greater distance to the combustion zone and each series of surrounding fuel streams must contact one or more radial impact structures provided on the exterior of the burner wall.

A fuel-fired burner 100 includes a combustion air inlet 113 for receiving combustion air coupled to a combustion air nozzle 136 at an input to a second chamber 152 within a burner housing 110 spaced apart from a third chamber 168 within the second chamber. The combustion air nozzle 136 directs the combustion air 171 into the third chamber 168. A fuel inlet 111 coupled to a burner nozzle 167 secured to a burner mounting plate 161 has a recycle port 164 for receiving hot exhaust gas provided to an exhaust gas path 165. A jet pump located entirely inside the burner housing is configured to receive the hot exhaust gas from the exhaust gas path. The jet pump operates by flowing the combustion air through the combustion air nozzle 136 which suctions in the hot exhaust gas through the recycle port into the exhaust gas path then into a gas mixing zone 178 for mixing the hot exhaust gas and the combustion air.

A fuel-fired burner 100 includes a combustion air inlet 113 for receiving combustion air coupled to a combustion air nozzle 136 at an input to a second chamber 152 within a burner housing 110 spaced apart from a third chamber 168 within the second chamber. The combustion air nozzle 136 directs the combustion air 171 into the third chamber 168. A fuel inlet 111 coupled to a burner nozzle 167 secured to a burner mounting plate 161 has a recycle port 164 for receiving hot exhaust gas provided to an exhaust gas path 165. A jet pump located entirely inside the burner housing is configured to receive the hot exhaust gas from the exhaust gas path. The jet pump operates by flowing the combustion air through the combustion air nozzle 136 which suctions in the hot exhaust gas through the recycle port into the exhaust gas path then into a gas mixing zone 178 for mixing the hot exhaust gas and the combustion air.

A cylindrical burner apparatus and method which produce low NO.sub.x emissions and low noise levels without being dependent upon a blower, or natural draft, for providing air flow or flue gas recirculation. A flow of combustion air is induced into an initial tube pass of the burner by discharging a gas fuel from a plurality of discharge ports located in the initial tube pass. At the same time, a flow of recycled flue gas is induced through a bypass duct between a subsequent tube pass of the burner and the initial tube pass by discharging one or more jets of gas fuel through the bypass duct.

A vehicle heater includes a burner area, a circumferential wall providing a combustion chamber, a flame tube with a first end forming or adjacent to a part of the combustion chamber circumferential wall and a second flame tube end. A heat exchanger housing has a circumferential wall enclosing the flame tube. A waste gas backflow space is formed, between an outer side of the flame tube and an inner side of the heat exchanger housing circumferential wall, with an inlet area at the second flame tube end and with an outlet area in the area of the first flame tube end. An inner dimension of the circumferential wall increases in the direction from an inlet area of the waste gas backflow space to an outlet area. An outer dimension of the flame tube increases in the direction from the second flame tube end to the first flame tube end.