EP4314655A1

EP4314655A1 - Burner

Info

Publication number: EP4314655A1
Application number: EP22716206.2A
Authority: EP
Inventors: Roman SCHIESSER
Original assignee: Mme Engineering EU
Current assignee: Mme Engineering EU
Priority date: 2021-03-23
Filing date: 2022-03-17
Publication date: 2024-02-07
Also published as: AT524888A1; WO2022200174A1

Abstract

The invention relates to a burner, comprising a lateral hot gas region (21) and an outer region (22), a feed line for primary air (3), a feed line for secondary air (1), and a feed line for fuel (2), wherein the feed line for secondary air (1) comprises three concentric cylindrical tubes, and the feed line for fuel (2) is arranged concentrically around the feed line for secondary air (1); wherein there is a first dead volume (4) within the burner between the feed line for secondary air (1) and the feed line for fuel (2), and wherein the feed line for fuel (2) has a nozzle structure (5) on the hot gas side (21); a second dead volume (9) is located between the feed line for secondary air (1) and the feed line for fuel (2) on the side of the outer region (22); and the feed line for primary air (3) is arranged concentrically around the feed line for fuel (2).

Description

Ultra low NOx burner

This invention relates to a combustor that produces a low NOx exhaust gas and a method of combusting fuel with a low NOx content in the exhaust gas.

Nitrogen oxides, chemically represented as the general formula NOx for various nitrogen oxides, are an environmentally harmful exhaust gas for which there are strict emission limits. Nitrogen oxides NOx are formed at high combustion temperatures from the nitrogen N ₂ in the air. These limit values must be observed under all circumstances. The NOx limit values 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 subsequent removal of NOx produced during combustion.

State of the art

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

DE102004059888A1 describes a burner for pulverized, liquid and gaseous fuels with a tubular primary air and dust feed, which forms a primary air and dust nozzle at its front end, and a ring-shaped secondary air feed surrounding it with a ring-shaped secondary air nozzle, through which part of the combustion air can be introduced in a twisted manner , a ring of tertiary air nozzles arranged outside the secondary air supply and a conical burner block, with the conical burner block directly adjoining the secondary air nozzle and being designed as a semi-combustor, and the tertiary air nozzle ring being arranged outside the conical, funnel-shaped opening of the burner block and comprising several individual nozzles. DE112011103913T5 describes a fuel dust fired

A boiler system in which a first nozzle for shooting out fuel dust to a furnace wall of a furnace and a second nozzle for shooting out air for high-temperature combustion as air for combustion are arranged alternately in the horizontal direction.

DE3623103A1 describes a continuous-flow or storage water heater with a combustion chamber heated by an atmospheric gas burner, via which heat exchange with the water takes place and which is connected to a supply air supply and exhaust gas discharge line with the interposition of a fan, the exhaust gas discharge line being connected directly to the supply air line via a branch line .

DE3832016A1 describes a method for the combustion of liquid or gaseous fuels, a mixture consisting of fuel and primary air as well as secondary air being fed to this combustion, with the primary air being mixed with a proportion of the exhaust gases produced during the combustion and the secondary air being mixed with a proportion of the fuel.

DE4133176A1 describes a burner for liquid and/or gaseous fuels, which in a burner housing has a primary air pipe with a fuel supply having a fuel outlet head and a secondary air pipe coaxial with the primary air pipe with a secondary air outlet at its free end, the secondary air pipe having the secondary air outlet through a burner axis limited in diameter tapered secondary air duct reduction ring.

DE4435640A1 describes a method for burning pulverized fuel, in particular coal, using a burner with a primary air tube carrying a mixture of air and fuel (primary air) and a jacket air tube carrying jacket air and surrounding the primary air tube, both containing the primary air and swirled jacket air exit into a burner muffle, forming a primary combustion zone with an internal recirculation area, in which, when the primary air exits, the pulverized coal concentration in the edge area of the primary air pipe is broken up, generating vortices, and in which the swirled stage air is fed to the primary flame, with the pulverized coal concentration in the Edge region, the flow rate of the primary air is changed and the staged air is introduced into a ring of individual jets surrounding the primary combustion zone in such a way that the overall staged air is imparted with a twist.

EP2498002B1 describes an industrial burner of a thermoprocessing system for the direct or indirect heating of a furnace chamber, which has a combustion chamber with at least one opening opening into a heating chamber, through which a material flow from the combustion chamber enters the heating chamber, and at least one heat exchange device, which flows from the heating chamber into the Heat exchange device promoted exhaust gas cools by heat exchange with combustion air, wherein the at least one heat exchange device extends in the axial direction at least partially along the combustion chamber, wherein thermal insulation is arranged between the combustion chamber and the at least one heat exchange device.

The aim of the present invention is to provide a burner which produces a low NOx content in the exhaust gas.

According to the invention this is achieved by providing a burner comprising a hot gas side region and an outer region, a primary air supply duct, a secondary air supply duct, a fuel supply duct, the secondary air supply duct comprising three concentrically arranged cylindrical tubes (an innermost tube, a middle tube and an outermost tube), where: the supply line for secondary air protrudes into the hot gas side area; the innermost tube is open to the outside and is open to the hot gas side; the middle tube is arranged concentrically around the innermost tube and has a dome-shaped closure which encloses the innermost tube on the hot gas side in a dome shape and is closed to the outside; the middle tube has overflow channels which are arranged in the outer area, have bores and are open in the direction of the outermost tube; the outermost tube is closed to the outside and is open to the hot gas side and has adjustable swirl vanes 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 there is a first dead volume inside the combustor 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 structure comprising: an annular orifice with holes; radially oriented injector suction nozzles in fluid communication with the holes and protruding on the suction side beyond the outer diameter of the primary air supply duct; wherein the holes in the ring diaphragm have an angle of attack of 0°-60°, preferably 10°-45°, in particular 45°, the annular diaphragm forming 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 outdoor side; the primary air supply line is arranged concentrically around the fuel supply line, which ends immediately after entering the hot gas side region and has: at the opening on the hot gas side, a conical taper of the diameter, the conical taper forming a truncated cone having an angle of 0 ° - 20°; an adjustable ring diaphragm at the opening of the conical taper facing the hot gas side; swirl plates adjustable in the angle of attack, which are arranged at an angle of 10° to 90°, preferably 40° to 70°.

This burner design achieves effective combustion of the fuel with a low NOx content in the exhaust gas. The secondary air is preheated in the dome-shaped shutter located on the hot gas side and enters the combustion chamber preheated. The baffles in the outermost tube of the secondary air supply line cause the secondary air to be distributed evenly around the circumference of the outermost tube, so that an even flow of secondary air enters the combustion chamber (i.e. the hot gas side) over the entire circumference of the opening. In addition, a vortex flow is forced by the swirl plates, which stabilizes the flame.

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

The outermost tube of the secondary air supply line and/or the dome-shaped closure of the middle tube of the secondary air supply line can be heat-resistant coated or formed of heat-resistant material, eg ceramic. The design of the nozzle in the fuel supply line causes the fuel to be evenly distributed over the entire circumference of the fuel supply line. The nozzle construction consists of an annular orifice with holes through which the fuel is fed into the combustion chamber and injector suction nozzles for sucking in exhaust gas from the surrounding area, which are built into this annular orifice. The injector intake nozzles are placed along the flow channels for the fuel. The injectors have tubular, elongated intake nozzles on the intake side. The length of the injector suction nozzles on the intake side is longer than the thickness of the primary air supply line, ie the injector suction nozzles can suck exhaust gas from the vicinity of the burner directly into the gaseous fuel flow. Alternatively, the intake ports of the injector priming nozzles face inward and are in fluid communication with the volume of exhaust gas surrounding the secondary air nozzle. The embodiment of the exhaust gas intake from the inside or from the outside depends on the structural conditions of the thermal process plant to be fired, with the embodiment with the intake from the outside offering the advantage that the exhaust gas sucked in is cooled in the intake pipes of the injectors by the outflowing primary air. The sucked in and cooled exhaust gas flow is introduced into the fuel flow. As a result, a fuel/exhaust gas mixture is obtained at the outlet of the fuel nozzles, which is reacted with oxygen in a combustion reaction. The proportion of exhaust gas in the fuel flow has a NOx-abatement effect, as the peak temperature in the flame remains low, resulting in less thermal NOx being produced.

The first dead volume is used for thermal insulation and can be filled with a suitable material for thermal insulation between the secondary air and fuel areas.

The conical taper in the primary air supply line serves to accelerate the primary air flow. The adjustable ring diaphragm and the swirl plates, which can be adjusted in the angle of attack, serve to Even distribution of the primary air over the entire circumference of the supply line or to create a vortex structure in the outflowing fluid.

In addition, due to this arrangement, the secondary air flow is fed to the combustion reaction with the fuel locally offset in the longitudinal axis. With this layout concept, staged combustion based on air staging is implemented.

A burner can cover an output range from 10 kWh to 100,000 kWh, which corresponds to an hourly natural gas consumption of 1 m ³ to 10,000 m ³ . The burner can be operated with any gaseous fuel, such as natural gas, methane, ethane, propane, butane, etc., as well as with pulverized solid fuels, such as pulverized coal, or gasified liquid fuels, such as hydrazine.

In one embodiment of the invention, the supply line for secondary air can be displaceable in length, the pipe-in-pipe system for supplying the secondary air protruding into the combustion chamber with a length L, the length L corresponding to the relationship L=D*f with D = outer diameter of

Primary air supply and f = 0 ≤ f ≤ 3 can be varied. This allows the design to be adapted to the flow rates of the gases (primary air, secondary air, fuel) and the requirements of the combustion. In particular, the concept of air staging for NOx reduction can be designed variably and optimized with regard to the highest possible NOx reduction.

In one embodiment of the invention, about 1/3 of the supply line for secondary air can protrude into the hot gas side area. This ensures good heat transfer to the secondary air. Preheating the secondary air ensures more stable and complete burnout of the remaining fuel. In another embodiment of the invention, the ratio of (outer diameter of innermost tube of

Supply line for secondary air) (hereinafter: ADi) :

(Outer diameter of middle secondary air supply pipe) (hereinafter: ADm) : (Outer diameter of outermost secondary air supply pipe) (hereinafter: ADa) about 0.7-1.3 : 1.26-2.34 : 1.82-3.38, preferably about 1:1.8:2.6. This represents an excellent geometry that delivers an improved combustion result.

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 is used for thermal insulation between the secondary air area and the fuel supply line.

In an embodiment of the invention, the ratio of (internal diameter of the fuel supply line) (hereinafter:

IDZ): (outer diameter of the feed line for fuel) hereinafter: ADZ) about 0.7-1.3: 0.98-1.82, preferably about 1: 1.4. This represents an excellent geometry that delivers an improved combustion result.

In an embodiment of the invention, the ratio of (internal diameter of the primary air supply line) (hereinafter:

IDP) : (outer diameter of the primary air supply line) (hereinafter: ADP) about 0.7-1.3 : 0.91-1.69, preferably about 1 : 1.3. This represents an excellent geometry that delivers an improved combustion result.

In one embodiment of the invention, the first dead volume can have vacuum or thermal insulation. This ensures that the fuel does not heat up before it enters the hot gas side. In one embodiment of the invention, the outermost pipe of the supply line for secondary air can have overflow ducts that open into the first dead volume, and the first dead volume has partitions that reduce the first dead volume, and the ring baffle can be adjustable and have passages on the inside. This creates a tertiary air flow that flows into the hot gas side area via an adjustable ring orifice on the inside of the fuel nozzle. This achieves more efficient and stable combustion.

In one embodiment of the invention, the radially aligned injector intake nozzle can have at least one guide plate that is aligned in the same way as the swirl plate in the primary air supply line. This gives the primary air an additional twist. This additionally supports the formation of a vortex flow of the primary air.

In one embodiment of the invention, the outermost tube of the supply line for secondary air can have a nozzle ring with outflow openings aligned radially or radially and axially at the outlet into the hot-gas side region.

In one embodiment of the invention, pipe sections can be arranged in the dome-shaped closure of the middle pipe of the secondary air supply line, which protrude through the dome-shaped closure at one end and protrude through a baffle at the opposite end. The returning secondary air uses the injector effect to “take along” exhaust gas from the combustion chamber and mix it with the secondary air. This gas mixture is burned with the fuel at the outflow openings of the secondary air supply line .

In one embodiment of the invention, the cross section of the annular orifice carrying natural gas has an outwardly directed cone, over which the primary air flows. With this geometry of the ring baffle, an inward flow of the primary air is forced. In addition to this, a cylindrical annular baffle can be placed on the cone for better alignment of the primary air flow.

In one embodiment of the invention, holes can be arranged on the annular diaphragm on the inside, which are in fluid communication with the holes in the annular diaphragm. As a result, exhaust gas is sucked into the fuel flow from the inside via the injector intake nozzle.

In one embodiment, an additive supply duct may be centrally located along the burner axis and protrude through the dome-shaped closure of the center tube of the secondary air supply duct, which duct has a nozzle on the hot gas side portion. The feed line can also be arranged radially around the burner. Combustible or non-combustible additives, such as waste oils and fuel oils, fatty solutions of animal or vegetable origin, organic waste materials and solvents, waste acids and alkalis, waste water, sulphurous liquids, chlorinated and halogenated gases and liquids can also be burned via this additional injection system through this supply line. The substances mentioned 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 sprayed into the flame of the burner in finely atomized form via a nozzle. Through this supply line, exhaust gas can also be drawn off to the outside in counterflow to the secondary air, as a result of which the secondary air flow is preheated.

In one embodiment, the outflow openings of the pipe sections on the side of the baffle plates can be narrowed by a cone (valve) that can be adjusted in the longitudinal direction. As a result, the total exhaust gas mass flow can be regulated in the secondary air flow. In one embodiment, an outer annular gap can be formed by two tubes that surround the burner on the outside, the inner of the two tubes having an opening and the outer of the two tubes having an outlet. Exhaust gas can be drawn off to the outside via the outer annular gap in counterflow to the primary air via the outlet, which is arranged on the outside of the two tubes, whereby the primary air flow is preheated. In addition to this, a closed combustion chamber is created through the inside of the two tubes, in which the staged combustion takes place and the hot gases can flow out via the opening arranged on the inside of the two tubes.

Another aspect of the invention relates to a method for burning fuel in a burner as defined above, secondary air being introduced into the supply line for secondary air in a burner as defined above, the secondary air being twisted by the swirl plates; Fuel is introduced into the fuel supply line, with the fuel being injected through the holes in the ring diaphragm at an outwardly directed angle of attack into the swirled primary air; Primary air is introduced into the supply line for primary air, the primary air being twisted by the swirl plates. This achieves efficient combustion with a low NOx content in the exhaust gas.

In an embodiment of the other aspect of the invention, the proportion of secondary air can be 20-50% by volume and the proportion of primary air 50-80% by volume of the total air required for combustion. This split ratio gives excellent exhaust performance.

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 about 1.0 to 2.0, preferably about 1.0 to 1.5, in particular about 1.0 to 1.1. A stoichiometric excess of air or oxygen can thus be used.

In an embodiment of the other aspect of the invention, the oxygen concentration in the secondary air and primary air can be from 21% by volume to 100% by volume. Accordingly, the nitrogen content has lower concentrations with increasing oxygen concentrations. through higher

Oxygen concentrations, combustion processes can be carried out much more efficiently, since the combustion temperature and the heat transfer based on the gas radiation increase significantly with increasing oxygen concentrations in the oxidizer flow. Thus, with this burner, an increase in energy efficiency can be achieved with low NOx emissions at the same time.

In one embodiment of the method, the primary air and secondary air can be an air/exhaust gas mixture, an air/oxygen mixture or an exhaust gas/oxygen mixture. A method of external exhaust gas circulation with oxygen enrichment can thus be implemented with the present burner. A partial flow of exhaust gas is branched off from the main flow, enriched with oxygen and fed to the burner at the inlets for primary and secondary air as an air substitute. The enthalpy of the recirculated exhaust gas oxygen mass flow can then be used directly to save energy. On the basis of this concept, not only NOx but also CO ₂ emissions can be drastically reduced.

In an embodiment of the other aspect of the invention, the fuel may comprise nitrogen. Nitrogenous fuels such as hydrazine can be used. Hydrocarbons used as fuels can also contain small amounts of nitrogen. With this burner, these fuels loaded with nitrogen can be burned without causing significant NOx emissions. In one embodiment, the fuel may include gaseous hydrocarbons, hydrogen, biogases, pulverized coal-air mixtures, hydrogen sulfides, carbon monoxide gas, carbon monoxide-hydrogen mixtures, coke oven gases, tail gases.

In one embodiment of the method, exhaust gas can be sucked directly into the fuel flow by the injector effect. This achieves more efficient NOx reduction.

In one embodiment of the method, the outwardly directed injector intake nozzles can be cooled by the outflowing primary air. This minimizes the thermal load on the injector intake nozzles.

In one embodiment of the method, the aspirated exhaust gas flow inside the injector intake nozzles under the

Condensation temperature (dew point) for the exhaust gas humidity are cooled, with water condensing out in the exhaust gas flow and the liquid water is introduced into the fuel flow. This also results in a lower combustion temperature, which suppresses thermal NOx formation.

In one embodiment of the method, exhaust gas can be sucked into the secondary air flow and subsequently an air-exhaust gas mixture can be brought to the nozzle opening of the secondary air for combustion with the injected fuel. The introduced exhaust gas reduces the combustion temperature and thus the NOx emissions.

In one embodiment of the method, the quantities of the material flows can be automatically controlled for low NOx and CO emissions on the basis of a rigidly functioning programmed logic or a neural network individually trained for the respective process conditions. This makes it easy to comply with the legal limit values. The following reference symbols are used in the examples and figures:

1 supply line for secondary air

11 innermost tube of the secondary air supply line lb middle tube of the secondary air supply line

1c Outer tube of the secondary air supply line

1d Dome-shaped closure of the middle pipe of the secondary air supply line

1e Overflow channels of the middle pipe of the secondary air supply line

1f Swirl plates for axial or radial twisting of the secondary air

1g overflow channel to the first dead volume

1h Nozzle ring with radial or radial and axially aligned outflow openings

1i Injector intake pipes for mixing exhaust gas from the combustion chamber into the secondary air flow 1j vane plate for narrowing the cross section in the return line of the secondary air for injector system for mixing exhaust gas into the secondary air

1k outer annular gap, which is formed by tubes lm and ln 1l exit on the outside of the two tubes 1n, which form the outer annular gap lk

1m the inner of the two tubes that form the outer annular gap 1k

1n the outer of the two tubes that form the outer annular gap 1k

1o opening on the inside of the two tubes lm, which form the outer annular gap lk

2 fuel supply line

2a supply line for additives

2b Nozzle on the feed line for additives

3 Primary air supply line

4 first dead volume 4a Foreclosure

5 Nozzle construction in the fuel supply line

5a ring diaphragm with holes

5b Holes in the ring diaphragm for fuel supply 5c Injector suction nozzles with suction nozzles directed radially outwards or inwards

5d Passage for tertiary air in the ring diaphragm

5e integrated baffles on the injector intake nozzles

5f Holes on the inside of the annular cover for the exhaust gas intake

9 second dead volume

10 adjustable ring baffles in the primary air supply line

11 baffles in the primary air supply line

21 Hot gas side area

22 outdoor area

drawings

Figure 1 shows a cross section of a burner of the invention.

2 shows a cross-section of a nozzle construction of the invention.

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

4 shows a three-dimensional view of a burner of the invention.

5 shows an embodiment of the invention with overflow openings and partitions.

6 shows a nozzle construction of an embodiment of the invention.

Fig. 7 shows another embodiment of the invention with integrated baffles on the injector suction nozzles. 8 shows yet another embodiment of the invention with a supply line for additives.

9 shows yet another embodiment of the invention with injector intake pipes for mixing exhaust gas from the combustion chamber into the secondary air flow.

FIG. 10 shows another embodiment of the invention with an adjustable ring diaphragm in the primary air supply line.

Fig. 11 shows a serrated nozzle gap that discharges the secondary air both axially and radially in relation to the longitudinal axis.

12 shows a control concept for regulating the low-NOx burner.

EXAMPLES

EXAMPLE 1 - Burner

A burner according to the invention comprises a hot gas side area 21 and an outer area 22, a primary air supply line 3, a secondary air supply line 1, a fuel supply line 2, the secondary air supply line 1 comprising three concentrically arranged cylindrical tubes an innermost tube 1a, a middle tube 1b and an outermost tube 1c, wherein: the secondary air supply duct 1 protrudes into the hot gas side portion 21; the innermost tube 1a is open to the outside area 22 and is open to the hot gas side 21; the middle tube 1b is arranged concentrically around the innermost tube la and has a dome-shaped closure ld, which encloses the innermost tube la on the hot gas side 21 in a dome shape and is closed to the outer area 22; the middle tube lb has overflow channels le, which are arranged in the outer area 22, have bores and are open in the direction of the outermost tube 1c; the outermost tube 1c is closed to the outside area 22 and is open to the hot gas side 21 and has adjustable swirl plates lf 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 terminating immediately after entering the hot gas side region 21; there being a first dead volume 4 inside the burner between the secondary air feed line 1 and the fuel feed line 2, and the fuel feed line 2 on the hot gas side 21 has a nozzle construction 5 comprising: an annular baffle 5a with holes 5b; radially directed injector suction nozzles 5c which are in fluid communication with the holes 5b and which protrude on the suction side beyond the outer diameter of the primary air supply pipe 3; the holes 5b in the ring diaphragm 5a have an angle of attack of 45°, the ring diaphragm 5a forming a truncated cone having an angle of attack of 30°, the base of the cone pointing in the direction of the outer area 22; a second dead volume 9 is arranged between secondary air supply pipe 1 and fuel supply pipe 2 on the outdoor area 22 side; the feed line for primary air 3 is arranged concentrically around the feed line for fuel 2, which ends immediately after entry into the hot gas side region 21 and has the following: at the opening on the hot gas side 21, a conical reduction in diameter, the conical reduction forming a truncated cone which has an angle of 10°; an adjustable ring diaphragm 10 at the opening of the conical taper facing the hot gas side 21; the angle of attack adjustable swirl plates 11, which are arranged at an angle of 55 °.

The length of the supply line for secondary air 1a, 1b, 1c can be adjusted. Approximately 1/3 of the supply line for secondary air 1 protrudes into the side area 21 of the hot gas.

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

The second dead volume 9 is about 1/5 of the length of the secondary air supply line 1.

The ratio of the inner diameter of the fuel supply line

2 : Outer diameter of the fuel supply line 2 is approx

1:1.4.

The ratio of the inside diameter of the primary air supply line

3: Outside diameter of the primary air supply line 3 is approx

1:1.3.

The first dead volume 4 has a vacuum or thermal insulation.

EXAMPLE 2 - Burner with transfer channels and adjustable nozzle ring

The burner as described in Example 1 is modified as follows: the outermost tube of the secondary air supply line 1c has overflow channels lg which open into the first dead volume 4, and the first dead volume 4 has partitions 4a which reduce first dead volume 4, and the ring diaphragm 5a is adjustable and has passages 5d on the inside.

EXAMPLE 3 Burners with baffles

The burner as described in Example 1 or Example 2 has the following modification: the radially aligned injector suction nozzle 5c has at least one guide plate 5e, which is aligned in the same way as the swirl plate 11 in the primary air supply line 3.

EXAMPLE 4 - Nozzle ring burner with radially oriented orifices

The burner as given in one of the above examples has the following modification: the outermost tube of the secondary air supply line 1c has a nozzle ring 1h with radially or radially and axially directed outflow openings at the outlet into the hot gas side area 21.

EXAMPLE 5 - Burner with stubs in dome closure

The burner as given in one of the above examples has the following modification: in the dome-shaped closure ld of the middle pipe of the secondary air supply line 1b there are pipe sections 1i which protrude at one end through the dome-shaped closure 1d and at the opposite end through a baffle 1j protrude.

EXAMPLE 6 - Burner with central feed for additives

The burner as given in one of the above examples has the following modification: an additive supply pipe 2a is arranged centrally along the burner axis and protrudes through the dome-shaped closure of the central tube of the supply pipe Secondary air ld, which supply line 2a on the hot gas side area 21 has a nozzle 2b.

EXAMPLE 7 - Procedure

In a burner as described in one of Examples 1 to 6, secondary air is introduced into the supply line for secondary air 1, the secondary air being twisted by the swirl plates 1f; Fuel is introduced into the fuel supply line 2, the fuel being injected through the holes in the ring diaphragm 5a at an outwardly directed angle of attack into the swirled primary air;

Primary air is introduced into the primary air supply line 3 , the primary air being twisted by the swirl plates 11 .

The proportion of secondary air is 40% by volume and the proportion of primary air is 60% by volume of the total air required for combustion.

The total air ratio for the sum of primary and secondary air λ is about 1.1.

The primary air and secondary air is an air-exhaust mixture.

The fuel is natural gas.

Exhaust gas is drawn directly into the fuel stream by injector action.

The outwardly directed injector intake nozzles 5c are cooled by the outflowing primary air.

The quantities of the material flows are controlled on the basis of a rigidly functioning programmed logic for low NOx and CO emissions.

Claims

Patent claims :

1. Burner, comprising a hot gas side area (21) and an outer area (22), a feed line for primary air (3), a feed line for secondary air (1), a feed line for fuel (2), characterized in that the feed line for secondary air ( 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) protrudes into the hot gas side region (21); the innermost tube (1a) is open to the outside (22) and is open to the hot gas side (21); the middle 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-shaped manner and is closed towards the outer area (22). ; the middle tube (1b) has overflow channels (1e) which are arranged in the outer area (22), have bores and are open in the direction of the outermost tube (1c); the outermost tube (1c) is closed to the outside area (22) and is open to 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 15° to 80° ; pipe sections (1i) being arranged in the dome-shaped closure (ld) of the middle pipe of the secondary air supply line (1b), which protrude through the dome-shaped closure (1d) at one end and protrude through a baffle (1j) at the opposite end; the fuel supply line (2) is arranged concentrically around the secondary air supply line (1) which ends immediately after entry into the hot gas side region (21); there being a first dead volume (4) inside the burner between the secondary air feed line (1) and the fuel feed line (2), and the fuel feed line (2) on the hot gas side

(21) has a nozzle construction (5) comprising: an annular orifice (5a) with holes (5b); radially directed injector suction nozzles (5c) which are in fluid communication with the holes (5b) and which protrude on the suction side beyond the outer diameter of the primary air supply duct (3); wherein the holes (5b) in the annular diaphragm (5a) have an angle of attack of 0° - 60°, preferably 10° - 45°, in particular 45°, the annular diaphragm (5a) forming a truncated cone having an angle of attack of 0° - 70°, preferably 20° - 45°, with the base of the cone pointing in the direction of the outer area (22); a second dead volume (9) between the secondary air supply line (1) and the fuel supply line (2) on the outdoor side

(22) is arranged; the feed line for primary air (3) is arranged concentrically around the feed line for fuel (2), which ends immediately after entering the hot gas side area (21) and has the following: at the opening on the hot gas side (21), a conical reduction in diameter, wherein the conical taper forms a truncated cone having an angle of 0° - 20°; an adjustable ring diaphragm (10) on the opening of the conical taper facing the hot gas side (21); swirl plates (11) adjustable in the angle of attack, which are arranged at an angle of 10° to 90°, preferably 40° to 70°.

2. Burner according to claim 1, characterized in that the supply line for secondary air (1a, 1b, 1c) is displaceable in length, the tube-in-tube system for supplying the Secondary air protrudes into the combustion chamber with a length L, where the length L can assume a value of 0 ≤ f ≤ 3 according to the relationship L = D * f with D = outer diameter of the primary air supply line and f, or about 1/3 of the supply line for secondary air (1) protrudes into the hot gas side area (21).

3. Burner according to one of claims 1 or 2, characterized in that 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, where ADi stands for the outer diameter of the innermost tube of the secondary air supply line (1a),

ADm is the outside diameter of the middle tube of the secondary air supply line (1b) and

ADa is the outside diameter of the outermost tube of the secondary air supply line (1c).

4. Burner according to one of the preceding claims, characterized in that the ratio of IDZ: ADZ about 0.7-1.3: 0.98-1.82, preferably about 1: 1.4, where IDZ for the Inner diameter of the fuel supply line (2) and

ADZ stands for the outer diameter of the fuel feed line (2).

5. Burner according to one of the preceding claims, characterized in that the ratio of IDP: ADP is about 0.7-1.3: 0.91-1.69, preferably about 1: 1.3, where IDP for the Inside diameter of the primary air supply line (3) and

ADP stands for the outside diameter of the primary air supply line (3).

6. Burner according to one of the preceding claims, characterized in that the outermost tube of the supply line for secondary air (1c)

has overflow channels (lg) 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 diaphragm (5a) is adjustable and passages (5d ) on the inside.

7. Burner according to one of the preceding claims, characterized in that the radially aligned injector suction nozzle (5c) has at least one guide plate (5e) which is aligned in the same way as the swirl plate (11) in the primary air supply line (3).

8. Burner according to one of the preceding claims, characterized in that the outermost tube of the supply line for secondary air (1c) has a nozzle ring (1h) with radially or radially and axially aligned outflow openings at the outlet into the hot gas side region (21).

9. Burner according to one of the preceding claims, characterized in that the cross section of the fuel-carrying ring diaphragm (5a) has an outwardly directed cone over which the primary air flows.

10. Burner according to one of the preceding claims, characterized in that on the annular diaphragm (5a) on the inside holes (5f) are arranged which are in fluid communication with the holes in the annular diaphragm (5b).

11. Burner according to one of the preceding claims, characterized in that a supply line for additives (2a) is arranged centrally along the burner axis and protrudes through the dome-shaped closure of the middle pipe of the supply line for secondary air (1d), which supply line (2a) has a nozzle (2b) on the hot gas side region (21) having.

12. Burner according to one of the preceding claims, characterized in that the outflow openings of the pipe sections (1i) on the side of the baffle plates (1j) can be narrowed by a cone (valve) adjustable in the longitudinal direction.

13. Burner according to one of the preceding claims, characterized in that an outer annular gap (1k) is formed by two tubes (1m, 1n) which surround the burner on the outside, the inner of the two tubes (1m) having an opening (10 ) and the outer of the two tubes (1n) has an outlet (11).

14. A method for the combustion of fuel, characterized in that in a burner according to one of claims 1 to 13, secondary air is introduced into the supply line for secondary air (1), the secondary air being twisted by the swirl plates (1f);

Fuel is introduced into the fuel supply line (2), the fuel being injected through the holes in the ring diaphragm (5a) at an outwardly directed angle of attack into the swirled primary air;

Primary air is introduced into the supply line for primary air (3), the primary air being twisted by the swirl plates (11); where appropriate, the proportion of secondary air is 20-50% by volume and the proportion of primary air is 50-80% by volume of the total air required for combustion.

15. The method according to claim 14, characterized in that the total air ratio 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 , amounts to; 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, characterized in that the fuel comprises nitrogen compounds, gaseous hydrocarbons, hydrogen, biogas, coal dust-air mixtures, hydrogen sulfides, carbon monoxide gas, carbon monoxide-hydrogen mixtures, coke oven gases, tail gases or mixtures thereof.

17. The method according to any one of claims 14 to 16, characterized in that

Exhaust gas is sucked directly into the fuel flow by the injector effect.

18. The method according to any one of claims 14 to 17, characterized in that the outwardly directed injector suction nozzles (5c) are cooled by the outflowing primary air; where necessary the aspirated exhaust gas stream inside the injector intake nozzles (5c) is cooled below the condensation temperature (dew point) for the exhaust gas humidity, water condensing out in the exhaust gas stream and the liquid water being introduced into the fuel stream.