BRENNER

Description

[0001] This invention relates to a burner that produces exhaust gas with a low NOx content, and to a method for burning fuel with a low proportion of NOx in the exhaust gas.

[0002] Nitrogen oxides, chemically represented by the general formula NOx for various nitrogen oxides, are a harmful exhaust gas for which strict emission limits exist. NOx are formed from nitrogen (N₂) in the air during high combustion temperatures. These limits must be adhered to under all circumstances. NOx limits can be achieved either on the burner side by controlling the combustion of the fuel and the air supply, or on the exhaust side by subsequently removing NOx produced during combustion. State of the art

[0003] Various burner types have been described in the literature, some of which achieve a low NOx concentration in the exhaust gas.

[0004] DE102004059888A1 describes a burner for powdery, liquid and gaseous fuels with a tubular primary air and dust supply which forms a primary air and dust nozzle at its front end, an annular secondary air supply surrounding this with an annular secondary air nozzle through which a portion of the combustion air can be introduced in a twisted manner, an annular tertiary air nozzle ring arranged outside the secondary air supply and a conical burner block, wherein the conical burner block connects directly to the secondary air nozzle and is designed as a semi-combustor, and the tertiary air nozzle ring is arranged outside the conical-funnel-shaped opening of the burner block and comprises several individual nozzles.

[0005] DE112011103913T5 describes a fuel dust-fired boiler system in which a first nozzle, to shoot fuel dust towards a furnace wall, and a second nozzle, to shoot air for high-temperature combustion, are arranged alternately in a horizontal direction.

[0006] DE3623103A1 describes a flow-through or storage water heater with a combustion chamber heated by an atmospheric gas burner, through which heat exchange to the water takes place and which is connected to an air supply and exhaust gas discharge line via an intermediate fan, wherein the exhaust gas discharge line is directly connected to the air supply line via a branch line.

[0007] DE3832016A1 describes a process for the combustion of liquid or gaseous fuels, wherein a mixture consisting of fuel and primary air as well as secondary air is supplied to this combustion, wherein a proportion of the exhaust gases produced during combustion is added to the primary air and a proportion of the fuel is added to the secondary air.

[0008] DE4133176A1 describes a burner for liquid and / or gaseous fuels, which has in a burner housing a primary air pipe with a fuel supply having a fuel outlet head and coaxial to the primary air pipe a secondary air pipe with a secondary air outlet at its free end, wherein the secondary air pipe limits the secondary air outlet by a secondary air channel reducing ring which tapers in diameter towards the burner axis.DE4435640A1 describes a method for the combustion of pulverized fuel, in particular coal, by means of a burner with a primary air pipe carrying a mixture of air and fuel (primary air) and a jacket air pipe carrying jacket air and surrounding the primary air pipe, in which the primary air and swirled jacket air exit into a burner muffle, forming a primary combustion zone with an internal recirculation area, in which, upon exit of the primary air, the coal dust concentration in the edge region of the primary air pipe is ruptured by generating vortices, and in which swirled stage air is supplied to the primary flame, wherein, before the coal dust concentration in the edge region is ruptured, the flow velocity of the primary air is changed and the stage air is introduced in a ring of individual jets surrounding the primary combustion zone in such a way that a swirl is imposed on the total stage air.

[0009] EP2498002B1 describes an industrial burner of a thermal processing plant for the direct or indirect heating of a furnace chamber, which has a combustion chamber with at least one opening leading into a heating chamber, through which a material flow from the combustion chamber into the heating chamber, and at least one heat exchanger device which cools exhaust gas conveyed from the heating chamber into the heat exchanger device by heat exchange with combustion air, wherein the at least one heat exchanger device extends at least partially along the combustion chamber in the axial direction, and wherein thermal insulation is arranged between the combustion chamber and the at least one heat exchanger device.

[0010] US6652268B1 describes a burner assembly comprising a housing with an air inlet and a burner end. An impeller mounted within the housing is connected to the air inlet and is designed to direct air to the burner end of the housing. The burner assembly also includes an internal air tube mounted at the burner end of the housing to define an inner and an outer combustion zone.The assembly also includes several radiation plates mounted at the burner end of the housing adjacent to the outer combustion zone; an inner air vortex vane mounted on the inner air tube to direct some of the air from the impeller into the inner combustion zone; an inner gas injection nozzle mounted on the inner air tube to direct gaseous fuel into the inner combustion zone; an outer air vortex vane mounted at the burner end of the housing to direct some of the air from the impeller into the outer combustion zone; and several outer gas injection nozzles mounted at the burner end of the housing to direct gaseous fuel into the outer combustion zone. A first crenellated ring is mounted around the circumference of the inner air tube, and a second crenellated ring is mounted around the circumference of the burner end of the housing.

[0011] US5807094A describes a premixed-air natural gas burner with reduced thermal and immediate NOx emissions, employing a central cylindrical core chamber and an outer annular chamber separated by a hollow cylinder. This cylinder features a plurality of gas nozzles at a front end of the burner adjacent to a burner throat. The plurality of gas nozzles introduces natural gas into a core chamber, with the airflow passing through a fixed swirl baffle and controlled by a sliding airflow damper connected to the central cylindrical core chamber. A reduced stoichiometric air-fuel ratio (of approximately 0.6) is preferably maintained at an outlet of the central cylindrical core chamber. The remainder of the combustion air is supplied through the outer annular chamber to maintain an overall or cumulative burner stoichiometric ratio of approximately 1.05.

[0012] The aim of the present invention is to provide a burner that produces a low NOx content in the exhaust gas.

[0013] According to the invention, this is achieved by providing a burner comprising a hot gas side area and an outer area, a primary air supply line, a secondary air supply line, and a fuel supply line, wherein The secondary air supply line comprises three concentrically arranged cylindrical tubes (an innermost tube, a middle tube, and an outermost tube), wherein: the secondary air supply line projects into the hot gas side region; the innermost tube is open to the outside and open to the hot gas side; the middle tube is arranged concentrically around the innermost tube and has a domed closure that domes around the innermost tube on the hot gas side and is closed to the outside; the middle tube has overflow channels located on the outside, which have bores and are open towards the outermost tube; the outermost tube is closed to the outside and open to the hot gas side and has adjustable swirl plates at the opening on the hot gas side, which have an angle of attack of 15° to 80°;The fuel supply line is arranged concentrically around the secondary air supply line, which terminates immediately after entering the hot gas side region; wherein a first dead volume exists inside the burner between the secondary air supply line and the fuel supply line; and wherein the fuel supply line on the hot gas side has a nozzle assembly comprising: an annular orifice with holes; radially oriented injector suction nozzles that are in fluid communication with the holes and that project beyond the outer diameter of the primary air supply line on the suction side; wherein the holes in the annular orifice have an angle of attack of 0° - 60°, preferably 10° - 45°, particularly 45°, wherein the annular orifice forms a truncated cone having an angle of attack of 0° - 70°, preferably 20° - 45°, with the base of the cone pointing towards the outside;A second dead volume is arranged between the secondary air supply line and the fuel supply line on the outer side; the primary air supply line is arranged concentrically around the fuel supply line, which terminates immediately after entering the hot gas side region and has the following: at the opening on the hot gas side, a conical taper in diameter, the conical taper forming a truncated cone with an angle of 0° - 20°; an adjustable annular orifice at the opening of the conical taper facing the hot gas side; swirl plates adjustable in their angle of attack, arranged at an angle of 10° to 90°, preferably 40° - 70°.

[0014] This burner design achieves efficient fuel combustion with low NOx emissions. Secondary air is preheated in the domed baffle located on the hot gas side and enters the combustion chamber preheated. Swirl plates in the outermost secondary air supply pipe ensure a uniform distribution of the secondary air around the circumference of the pipe, resulting in a consistent secondary airflow into the combustion chamber (i.e., the hot gas side) across the entire opening. Additionally, the swirl plates create a vortex flow that stabilizes the flame.

[0015] The "primary air supply line" can also be called "primary air supply line", the "secondary air supply line" can also be called "secondary air supply line" and the "fuel supply line" can also be called "fuel supply line".

[0016] The outermost pipe of the secondary air supply line and / or the domed closure of the middle pipe of the secondary air supply line may be coated with heat-resistant material or made of heat-resistant material, e.g. ceramic.

[0017] The nozzle design in the fuel supply line ensures a uniform distribution of fuel across its entire circumference. The nozzle design consists of an annular orifice plate through which the fuel is fed into the combustion chamber, and injector intake nozzles integrated into this annular orifice plate to draw in exhaust gas from the immediate vicinity. These injector intake nozzles are positioned along the fuel flow channels. The injectors feature tubular, elongated intake nozzles on the intake side. The length of the injector intake nozzles is greater than the diameter of the primary air supply line, allowing them to draw exhaust gas from the immediate vicinity of the burner directly into the gaseous fuel stream. Alternatively, the intake openings of the injector intake nozzles can be directed inwards and be in fluid contact with the exhaust gas volume surrounding the secondary air nozzle.The design of the exhaust gas intake, whether from inside or outside, depends on the structural conditions of the thermal processing plant being fueled. The design with external intake offers the advantage that the intake gas is cooled in the injector intake pipes by the outgoing primary air. The intake and cooled exhaust gas stream is then introduced into the fuel stream. This results in a fuel-exhaust gas mixture at the fuel nozzle outlet, which reacts with oxygen in a combustion reaction. The exhaust gas component in the fuel stream reduces NOx emissions because the peak flame temperature remains low, thus reducing the formation of thermal NOx.

[0018] The first dead volume serves for thermal insulation and can be filled with a suitable material for thermal insulation between the secondary air and fuel areas.

[0019] The conical taper in the primary air supply line serves to accelerate the primary airflow. The adjustable annular orifice and the swirl plates, which can be adjusted in their angle of attack, ensure a uniform distribution of the primary air over the entire circumference of the supply line and / or create a vortex structure in the outgoing fluid.

[0020] Furthermore, this arrangement causes the secondary airflow to be locally offset along the longitudinal axis before being introduced into the combustion reaction with the fuel. This arrangement concept achieves staged combustion based on air staging.

[0021] A burner can cover a power range from 10 kWh to 100,000 kWh, which corresponds to an hourly natural gas consumption of 1 m³ to 10,000 m³. The burner can be operated with any gaseous fuel, such as natural gas, methane, ethane, propane, butane, etc., as well as with powdered solid fuels, such as pulverized coal, or gasified liquid fuels, such as hydrazine.

[0022] In one embodiment of the invention, the secondary air supply line can be length-adjustable, with the pipe-in-pipe system for the secondary air supply projecting into the combustion chamber with a length L. This length L can be varied according to the relationship L = D * f, where D = outer diameter of the primary air supply line and f = 0 ≤ f ≤ 3. This allows the design to be adapted to the flow velocities of the gases (primary air, secondary air, fuel) and the combustion requirements. In particular, the concept of air staging for NOx reduction can be variably designed and optimized with a view to achieving the highest possible NOx reduction.

[0023] In one embodiment of the invention, approximately one-third of the secondary air supply line can extend into the hot gas side area. This ensures good heat transfer to the secondary air. Preheating the secondary air ensures a more stable and complete combustion of the remaining fuel.

[0024] In another embodiment of the invention, the ratio of (outer diameter of innermost secondary air supply pipe) (hereinafter: ADi) : (outer diameter of middle secondary air supply pipe) (hereinafter: ADm) : (outer diameter of outermost secondary air supply pipe) (hereinafter: ADa) can be approximately 0.7-1.3 : 1.26-2.34 : 1.82-3.38, preferably approximately 1 : 1.8 : 2.6. This represents an excellent geometry that delivers improved combustion.

[0025] In one embodiment of the invention, the second dead volume can be approximately 1 / 5 of the length of the secondary air supply line. This serves as thermal insulation between the secondary air area and the fuel supply line.

[0026] In one embodiment of the invention, the ratio of (inner diameter of the fuel supply line) (hereinafter: IDZ) : (outer diameter of the fuel supply line) (hereinafter: ADZ) can be approximately 0.7-1.3 : 0.98-1.82, preferably approximately 1 : 1.4. This represents an excellent geometry that provides improved combustion.

[0027] In one embodiment of the invention, the ratio of (inner diameter of the primary air supply line) (hereinafter: IDP) : (outer diameter of the primary air supply line) (hereinafter: ADP) can be approximately 0.7-1.3 : 0.91-1.69, preferably approximately 1 : 1.3. This represents an excellent geometry that delivers improved combustion.

[0028] In one embodiment of the invention, the first dead volume can be a vacuum or thermally insulated. This ensures that the fuel does not heat up before entering the hot gas side.

[0029] In one embodiment of the invention, the outermost pipe of the secondary air supply line can have overflow channels opening into the first dead volume, and the first dead volume can have baffles that reduce its size. The annular orifice can also be adjustable and have openings on its inner surface. This creates a tertiary airflow that flows into the hot gas side region via an adjustable annular orifice on the inside of the fuel nozzle. This results in more efficient and stable combustion.

[0030] In one embodiment of the invention, the radially oriented injector intake nozzle can have at least one guide plate that is oriented in the same way as the swirl plate in the primary air supply line. This imparts an additional swirl to the primary air. This further promotes the formation of a vortex flow in the primary air.

[0031] In one embodiment of the invention, the outermost pipe of the secondary air supply line can have a nozzle ring with radially or radially and axially oriented outflow openings at the outlet into the hot gas side area.

[0032] In one embodiment of the invention, pipe sections can be arranged in the domed closure of the central pipe of the secondary air supply line. These pipe sections protrude through the domed closure at one end and through a dust baffle at the opposite end. The backflowing secondary air, acting as an injector, carries exhaust gas from the combustion chamber and mixes it with the secondary air. This gas mixture is then combusted with the fuel at the outlet openings of the secondary air supply line. The dust baffle creates the back pressure necessary for the injector action and the associated downstream pressure drop.

[0033] In one embodiment of the invention, the cross-section of the natural gas-carrying annular orifice has an outwardly directed cone over which the primary air flows. This geometry of the annular orifice forces an inward flow of the primary air. Additionally, a cylindrical annular orifice can be mounted on the cone to better align the primary air flow.

[0034] In one embodiment of the invention, holes can be arranged on the inside of the annular orifice, which are in fluid communication with the holes in the annular orifice. This allows exhaust gas to be drawn from the inside into the fuel stream via the injector intake nozzle.

[0035] In one embodiment, a feed line for additives can be arranged centrally along the burner axis and protrude through the domed closure of the central pipe of the secondary air supply line, which has a nozzle on the hot gas side. The feed line can also be arranged radially around the burner. Through this feed line, flammable or non-flammable additives, such as waste oils and heating oils, fatty solutions of animal or vegetable origin, organic waste materials and solvents, waste acids and alkalis, wastewater, sulfur-containing liquids, chlorinated and halogenated gases and liquids, can be co-combusted via this additional injection system. The aforementioned substances are supplied to the combustion chamber by means of the additional feed line, which is arranged centrally along the burner axis or radially around the burner. The additives are finely atomized and injected into the burner flame via a nozzle.This supply line also allows exhaust gas to be drawn off to the outside in counterflow to the secondary air, thereby preheating the secondary airflow.

[0036] In one embodiment, the outlet openings of the pipe sections on the side of the baffles can be narrowed by a longitudinally adjustable cone (valve). This allows the total exhaust gas mass flow in the secondary airflow to be regulated.

[0037] In one embodiment, an outer annular gap can be formed by two tubes surrounding the burner, the inner tube having an opening and the outer tube having an outlet. Exhaust gas can be drawn off through the outer annular gap in counterflow to the primary air via the outlet located in the outer tube, thereby preheating the primary airflow. Additionally, the interior of the two tubes creates a closed combustion chamber in which staged combustion takes place and the hot gases can escape through the opening located on the inside of the tubes.

[0038] Another aspect of the invention relates to a method for burning fuel in a burner as defined above, wherein secondary air is introduced into the secondary air supply line of a burner as defined above, wherein the secondary air is swirled by the swirl plates; fuel is introduced into the fuel supply line, wherein the fuel is injected into the swirled primary air at an outward angle through the holes in the annular orifice; primary air is introduced into the primary air supply line, wherein the primary air is swirled by the swirl plates. This achieves efficient combustion with a low NOx content in the exhaust gas.

[0039] In one embodiment of the other aspect of the invention, the proportion of secondary air can be 20-50 vol.% and the proportion of primary air 50-80 vol.% of the total air required for combustion. This ratio results in excellent exhaust gas characteristics.

[0040] In one embodiment of the other aspect of the invention, the total air ratio for the sum of primary and secondary air λ can be approximately 1.0 to 2.0, preferably approximately 1.0 to 1.5, and particularly approximately 1.0 to 1.1. This allows for the use of a stoichiometric excess of air or oxygen.

[0041] In one embodiment of the other aspect of the invention, the oxygen concentration in the secondary and primary air can range from 21% to 100% by volume. Accordingly, the nitrogen content decreases with increasing oxygen concentrations. Higher oxygen concentrations allow combustion processes to be conducted much more efficiently, as the combustion temperature and heat transfer based on gas radiation increase significantly with rising oxygen concentrations in the oxidizer stream. Thus, this burner enables increased energy efficiency while simultaneously reducing NOx emissions.

[0042] In one configuration of the process, the primary and secondary air can be an air-exhaust mixture, an air-oxygen mixture, or an exhaust gas-oxygen mixture. Thus, the burner in question enables an external exhaust gas recirculation process with oxygen enrichment. In this process, a partial exhaust gas stream is diverted from the main stream, enriched with oxygen, and supplied to the burner at the primary and secondary air inlets as a substitute for air. The enthalpy of the recirculated exhaust gas-oxygen mass flow can then be used directly for energy savings. Based on this concept, not only NOx but also CO₂ emissions can be drastically reduced.

[0043] In one embodiment of the other aspect of the invention, the fuel can comprise nitrogen. Nitrogen-containing fuels such as hydrazine can be used. Hydrocarbons used as fuels can also contain small amounts of nitrogen. With this burner, these nitrogen-laden fuels can be combusted without causing significant NOx emissions.

[0044] In one embodiment, the fuel may include or be gaseous hydrocarbons, hydrogen, biogas, coal dust-air mixtures, hydrogen sulfide, carbon monoxide gas, carbon monoxide-hydrogen mixtures, coke oven gases, tail gases.

[0045] In one version of the process, exhaust gas can be drawn directly into the fuel stream via the injector action. This results in more efficient NOx reduction.

[0046] In one embodiment of the process, the outward-facing injector intake nozzles can be cooled by the outgoing primary air. This minimizes the thermal stress on the injector intake nozzles.

[0047] In one embodiment of the process, the aspirated exhaust gas stream inside the injector intake nozzles can be cooled below the condensation temperature (dew point) for the exhaust gas moisture, causing water in the exhaust gas stream to condense and the liquid water to be introduced into the fuel stream. This also results in a lower combustion temperature, thereby suppressing thermal NOx formation.

[0048] In one version of the process, exhaust gas can be drawn into the secondary air stream, and subsequently, an air-exhaust gas mixture is introduced at the secondary air nozzle opening for combustion with the injected fuel. The introduced exhaust gas reduces the combustion temperature and thus the NOx emissions.

[0049] In a training program for this process, the quantities of material flows can be automatically controlled for low NOx and CO emissions based on a rigidly functioning programmed logic or a neural network individually trained for the respective process conditions. This makes it easy to comply with legal limits.

[0050] The following reference symbols are used in the examples and figures: 1 Secondary air supply line 1a Innermost pipe of the secondary air supply line 1b Middle pipe of the secondary air supply line 1c Outermost pipe of the secondary air supply line 1d Dome-shaped closure of the middle pipe of the secondary air supply line 1e Transfer channels of the middle pipe of the secondary air supply line 1f Swirl plates for axial or radial swirl of the secondary air 1g Transfer channel to the first dead volume 1h Nozzle ring with radial or radially and axially oriented outlet openings 1i Injector intake pipes for mixing exhaust gas from the combustion chamber into the secondary air flow 1j Baffle plate for cross-sectional reduction in the secondary air return line for injector system for mixing exhaust gas into the secondary air 1k Outer annular gap formed by pipes 1m and 1n 1l Outlet on the outer of the two pipes 1n forming the outer annular gap 1k 1m The inner of the both tubes that form the outer annular gap 1k 1nthe outer of the two tubes,10 Opening on the inner of the two pipes 1m that form the outer annular gap 1k 2 Fuel supply line 2a Additive supply line 2b Nozzle on the additive supply line 3 Primary air supply line 4 First dead volume 4a Partition 5 Nozzle assembly in the fuel supply line 5a Ring orifice with holes 5b Holes in the ring orifice for fuel supply 5c Injector intake nozzles with radially outward or inward directed intake nozzles 5d Tertiary air passage in the ring orifice 5e Integrated guide vanes on the injector intake nozzles 5f Holes on the inside of the ring orifice for exhaust gas intake 9 Second dead volume 10 Adjustable ring orifice in the primary air supply line 11 Swirl plates in the primary air supply line 21 Hot gas side area 22 Outer area Drawings

[0051] Fig. 1 shows a cross-section of a burner of the invention.

[0052] Fig. 2 shows a cross-section of a nozzle construction of the invention.

[0053] Fig. 3 shows a burner of the invention with an axial outflow of secondary air into the hot gas area.

[0054] Fig. 4 shows a three-dimensional view of a burner of the invention.

[0055] Fig. 5 shows an embodiment of the invention with overflow openings and partitions.

[0056] Fig. 6 shows a nozzle design of an embodiment of the invention.

[0057] Fig. 7 shows another embodiment of the invention with integrated guide plates on the injector intake nozzles.

[0058] Fig. 8 shows yet another embodiment of the invention with a supply line for additives.

[0059] Fig. 9 Figure 1 shows another embodiment of the invention with injector intake pipes for mixing exhaust gas from the combustion chamber into the secondary air stream.

[0060] Fig. 10 shows yet another embodiment of the invention with an adjustable ring orifice in the primary air supply line.

[0061] Fig. 11 shows a jagged nozzle gap that allows the secondary air to flow out both axially and radially in relation to the longitudinal axis.

[0062] Fig. 12 shows a control concept for regulating the low-NOx burner. EXAMPLES EXAMPLE 1 - Burner

[0063] A burner according to the invention comprises a hot gas side area 21 and an outer area 22, a supply line for primary air 3, a supply line for secondary air 1, a supply line for fuel 2, wherein The secondary air supply line 1 comprises three concentrically arranged cylindrical tubes: an innermost tube 1a, a middle tube 1b, and an outermost tube 1c, wherein: the secondary air supply line 1 projects into the hot gas side region 21; the innermost tube 1a is open towards the outer region 22 and is open towards the hot gas side 21; the middle tube 1b is arranged concentrically around the innermost tube 1a and has a domed closure 1d that domes around the innermost tube 1a on the hot gas side 21 and is closed towards the outer region 22; the middle tube 1b has overflow channels 1e that are arranged in the outer region 22, have bores, and are open towards the outermost tube 1c; the outermost tube 1c is closed towards the outside 22 and is open towards the hot gas side 21 and has adjustable swirl plates 1f at the opening on the hot gas side 21, which have an angle of attack of 40°;The fuel supply line 2 is arranged concentrically around the secondary air supply line 1, which terminates immediately after entering the hot gas side region 21; wherein a first dead volume 4 exists inside the burner between the secondary air supply line 1 and the fuel supply line 2, and wherein the fuel supply line 2 has a nozzle assembly 5 on the hot gas side 21 comprising: an annular orifice 5a with holes 5b; radially oriented injector intake nozzles 5c, which are in fluid communication with the holes 5b and which project beyond the outer diameter of the primary air supply line 3 on the intake side; wherein the holes 5b in the annular orifice 5a have an angle of attack of 45°, wherein the annular orifice 5a forms a truncated cone having an angle of attack of 30°, the base of the cone pointing towards the outer area 22;A second dead volume 9 is arranged between the secondary air supply line 1 and the fuel supply line 2 on the exterior side 22; the primary air supply line 3 is arranged concentrically around the fuel supply line 2, which terminates immediately after entering the hot gas side region 21 and has the following: at the opening on the hot gas side 21, a conical taper of diameter, the conical taper forming a truncated cone with an angle of 10°; an adjustable annular orifice 10 at the opening of the conical taper facing the hot gas side 21; swirl plates 11, adjustable in their angle of attack and arranged at an angle of 55°.

[0064] The supply line for secondary air 1a, 1b, 1c is adjustable in length. Approximately 1 / 3 of the supply line for secondary air 1 extends into the hot gas side area 21.

[0065] The ratio of the outer diameter of the innermost pipe 1a of the secondary air supply line : outer diameter of the middle pipe 1b of the secondary air supply line : outer diameter of the outermost pipe 1c of the secondary air supply line is approximately 1 : 1.8 : 2.6.

[0066] The second dead volume 9 is approximately 1 / 5 of the length of the secondary air supply line 1.

[0067] The ratio of the inner diameter of the fuel supply line 2 : outer diameter of the fuel supply line 2 is approximately 1 : 1.4.

[0068] The ratio of the inner diameter of the primary air supply line 3 to the outer diameter of the primary air supply line 3 is approximately 1 : 1.3.

[0069] The first dead volume 4 has a vacuum or thermal insulation. EXAMPLE 2 - Burner with overflow channels and adjustable nozzle ring

[0070] The burner as described in Example 1 is modified as follows: the outermost pipe of the secondary air supply line 1c has overflow channels 1g which open into the first dead volume 4, and the first dead volume 4 has partitions 4a which reduce the first dead volume 4, and the ring orifice 5a is adjustable and has openings 5d on the inside. EXAMPLE 3 Burner with guide plates

[0071] The burner as described in Example 1 or Example 2 has the following modification: the radially oriented injector suction nozzle 5c has at least one guide plate 5e that is aligned in the same way as the swirl plate 11 in the supply line for primary air 3. EXAMPLE 4 - Burner with nozzle ring with radially aligned outlet openings

[0072] The burner, as shown in one of the examples above, has the following modification: the outermost pipe of the secondary air supply line 1c has a nozzle ring 1h with radially or radially and axially aligned outflow openings at the outlet into the hot gas side area 21. EXAMPLE 5 - Burner with pipe sections in a domed closure

[0073] The burner, as shown in one of the examples above, has the following modification: in the domed closure 1d of the middle pipe of the secondary air supply line 1b, pipe sections 1i are arranged which protrude at one end through the domed closure 1d and at the opposite end through a dust baffle 1j. EXAMPLE 6 - Burner with central supply line for additives

[0074] The burner, as shown in one of the examples above, has the following modification: a supply line for additives 2a is arranged centrally along the burner axis and protrudes through the domed closure of the middle tube of the supply line for secondary air 1d, which supply line 2a has a nozzle 2b on the hot gas side area 21. EXAMPLE 7 - Procedure

[0075] In a burner as described in one of Examples 1 to 6, secondary air is introduced into the secondary air supply line 1, whereby the secondary air is swirled by the swirl plates 1f; fuel is introduced into the fuel supply line 2, whereby the fuel is injected into the swirled primary air at an outward angle through the holes in the annular orifice 5a; primary air is introduced into the primary air supply line 3, whereby the primary air is swirled by the swirl plates 11.

[0076] The proportion of secondary air is 40 vol.% and the proportion of primary air is 60 vol.% of the total air required for combustion.

[0077] The total air number for the sum of primary and secondary air λ is approximately 1.1.

[0078] Primary air and secondary air are an air-exhaust mixture.

[0079] The fuel is natural gas.

[0080] Exhaust gas is drawn directly into the fuel stream through the injector action.

[0081] The outward-facing injector intake nozzles 5c are cooled by the outgoing primary air.

[0082] The quantities of material flows are controlled based on a rigidly functioning programmed logic for low NOx and CO emissions.

Claims

1. A burner, comprising a hot gas side region (21) and an outer region (22), a primary air supply line (3), a secondary air supply line (1), a fuel supply line (2), wherein the secondary air supply line (1) comprises three concentrically arranged cylindrical tubes (an innermost tube (1a), a central tube (1b) and an outermost tube (1c)), wherein: the secondary air supply line (1) extends into the hot gas side region (21); the innermost pipe (1a) is open towards the outer region (22) and is open towards the hot gas side (21); the central tube (1b) is arranged concentrically around the innermost tube (1a) and has a dome-shaped closure (1d) which encloses the innermost tube (1a) on the hot gas side (21) in a dome shape and is closed towards the outer region (22); the central tube (1b) has overflow channels (1e) which are arranged in the outer region (22), have bores and are open in the direction of the outermost tube (1c); the outermost tube (1c) is closed towards the outer region (22) and is open towards the hot gas side (21) and has adjustable swirl plates (1f) at the opening on the hot gas side (21), having a pitch of 15° to 80°; wherein pipe sections (1i) are optionally arranged in the dome-shaped closure (1d) of the central pipe of the secondary air supply line (1b), projecting through the dome-shaped closure (1d) at one end and projecting through a backup orifice (1j) at the opposite end; the fuel supply line (2) is arranged concentrically around the secondary air supply line (1), which terminates immediately after entering the hot gas side region (21); wherein a first dead volume (4) exists inside of the burner between the secondary air supply line (1) and the fuel supply line (2), and wherein the fuel supply line (2) on the hot gas side (21) has a nozzle structure (5) comprising: an annular orifice (5a) having holes (5b); radially aligned injector intake nozzles (5c) in fluid communication with the holes (5b) and projecting beyond the outer diameter of the primary air supply line (3) on the intake side; wherein the holes (5b) in the annular orifice (5a) have a pitch of 0° - 60°, preferably 10° - 45°, in particular 45°, wherein the annular orifice (5a) forms a truncated cone having a pitch of 0° - 70°, preferably 20° - 45°, preferably 20° - 45°, wherein the cone base is directed towards the outer region (22); wherein a second dead volume (9) is arranged between the secondary air supply line (1) and the fuel supply line (2) on the side of the outer region (22); the primary air supply line (3) is arranged concentrically around the fuel supply line (2), terminating immediately after entering the hot gas side region (21) and having: at the opening on the hot gas side (21), a conical diameter taper, the conical taper forming a truncated cone having angle of 0° - 20°; an adjustable ring orifice (10) at the opening of the conical taper facing the hot gas side (21); swirl plates (11) which are pitch-adjustable and which are arranged at an angle of 10° to 90°, preferably 40° - 70°.

2. The burner according to Claim 1, wherein the secondary air supply line (1a, 1b, 1c) is moveable in length, wherein the pipe-in-pipe system for supplying the secondary air projects into the combustion chamber over a length L, wherein said length L corresponds to the relationship L = D * f, wherein D is the outer diameter of the primary air supply line and f may assume a value of 0 ≤ f ≤ 3, or wherein approximately 1 / 3 of the secondary air supply line (1) projects into the hot gas side region (21).

3. The burner according to any one of claims 1 or 2, wherein the ratio of ADi:ADm:ADa is about 0.7-1.3:1.26-2.34:1.82-3.38, preferably about 1:1.8:2.6, wherein ADi represents the outer diameter of the innermost tube of the secondary air supply line (1a), ADm represents the outer diameter of the central tube of the secondary air supply line (1b), and ADa represents the outer diameter of the outermost pipe of the secondary air supply line (1c).

4. The burner according to any one of the preceding claims, wherein the ratio of IDZ:ADZ is about 0.7-1.3:0.98-1.82, preferably about 1:1.4, wherein IDZ represents the inner diameter of the fuel supply line (2), and ADZ represents the outer diameter of the fuel supply line (2).

5. The burner according to any one of the preceding claims, wherein the ratio of IDP:ADP is about 0.7-1.3:0.91-1.69, preferably about 1:1.3, wherein IDP represents the inner diameter of the primary air supply line (3), and ADP represents the outer diameter of the primary air supply line (3).

6. The burner according to any one of the preceding claims, wherein the outermost pipe of the secondary air supply line (1c) has overflow channels (1g) opening into the first dead volume (4), and the first dead volume (4) has partitions (4a) reducing the first dead volume (4), and the annular orifice (5a) is adjustable and has passages (5d) on the inside thereof.

7. The burner according to any one of the preceding claims, wherein the radially aligned injector intake nozzle (5c) has at least one baffle (5e) which is oriented in the same way as the swirl plate (11) in the primary air supply line (3).

8. The burner according to any one of the preceding claims, wherein the outermost tube of the secondary air supply line (1c) has a nozzle ring (1h) with radially or radially and axially oriented outflow openings at the outlet into the hot gas side region (21).

9. The burner according to any one of the preceding claims, wherein the cross-section of the fuel carrying annular orifice (5a) has an outwardly directed cone having primary air flowing across the same.

10. The burner according to any one of the preceding claims, wherein holes (5f) are arranged on the inside of the annular orifice (5a), which are in fluid communication with the holes in the annular orifice (5b).

11. The burner according to any one of the preceding claims, wherein a supply line for additives (2a) is arranged centrally along the burner axis and projects through the dome-shaped closure of the central pipe of the secondary air supply line (1d), the supply line (2a) having a nozzle (2b) on the hot gas side region (21).

12. The burner according to any one of the preceding claims, wherein the outflow openings of the pipe sections (1i) on the side of the damming orifices (1j) may be narrowed by a cone (valve) adjustable in longitudinal direction.

13. The burner according to any one of the preceding claims, wherein an outer annular gap (1k) is formed by two tubes (1m, 1n) surrounding the burner on the outside, the inner one of the two tubes (1m) having an opening (1o) and the outer one of the two tubes (1n) having an outlet (11).

14. A method for the combustion of fuel, wherein secondary air is introduced into the secondary air supply line (1) in a burner according to any one of claims 1 to 13, wherein the secondary air is swirled by the swirl plates (1f); fuel is introduced into the fuel supply line (2), said fuel being injected into the swirled primary air through the holes in the annular orifice (5a) at an outwardly directed pitch; primary air is introduced into the primary air supply line (3), the primary air being swirled by the swirl plates (11); the proportion of secondary air optionally being 20-50% by volume and the proportion of primary air being 50-80% by volume of the total air required for combustion.

15. The method according to claim 14, wherein the total air number for the sum of primary and secondary air λ is about 1.0 to 2.0, preferably about 1.0 to 1.5, in particular about 1.0 to 1.1, and / or the oxygen concentration in the secondary air and primary air is from 21 % by volume to 100 % by volume; and / or the primary air and secondary air is an air / exhaust gas mixture, an air / oxygen mixture or an exhaust gas / oxygen mixture.

16. The method according to any one of claims 14 or 15, wherein the fuel comprises nitrogen compounds, gaseous hydrocarbons, hydrogen, biogases, pulverized coal-air mixtures, hydrogen sulfides, carbon monoxide gas, carbon monoxidehydrogen mixtures, coke oven gases, tail gases or mixtures thereof.

17. The method according to any one of claims 14 to 16, wherein exhaust gas is sucked directly into the fuel stream by the injector action.

18. The method according to any one of claims 14 to 17, wherein the outwardly directed injector intake nozzles (5c) are cooled by the outflowing primary air; optionally wherein the sucked exhaust gas stream inside the injector intake nozzles (5c) is cooled below the condensation temperature (dew point) for the exhaust gas moisture, wherein water within the exhaust gas stream is condensed off and the liquid water is introduced into the fuel stream.