ULTRA LOW NOx BURNER

Abstract

A burner includes a hot gas zone and an outer zone, a primary air feed line, a secondary air feed line, and a fuel feed line. The secondary air feed line includes three concentric cylindrical tubes. The fuel feed line is arranged concentrically around the secondary air feed line. A first dead volume exists inside the burner between the secondary air feed line and the fuel feed line. The fuel feed line has a nozzle construction on the hot gas side. A second dead volume is arranged between the secondary air feed line and the fuel feed line on the outer side zone. The primary air feed line is arranged concentrically around the fuel feed line.

Claims

1. A burner, comprising a hot gas zone (21) and an outer zone (22), a primary air feed line (3), a secondary air feed line (1), a fuel feed line (2), wherein, the secondary air feed line (1) comprises three concentric cylindrical tubes (an innermost tube (1a), a middle tube (1b) and an outermost tube (1c)), wherein: the secondary air feed line (1) protrudes into the hot gas zone (21); the innermost tube (1a) is open to the outer zone (22) and open to the hot gas zone (21); the middle tube (1b) is arranged concentrically around the innermost tube (1a) and has a dome-shaped seal (1d), which encloses the innermost tube (1a) on the hot gas side (21) dome-like and is closed off towards the outer zone (22); the middle tube (1b) comprises overflow channels (le), which are arranged in the outer zone (22), comprise holes and are open towards the outermost tube (1c); the outermost tube (1c) is closed off towards the outer zone (22) and open to the hot gas side (21) and comprises adjustable swirl vanes (1f) near the opening on the hot gas side (21) at an angle of attack of 15? to 80?; optionally wherein tube sections (1i) are arranged in the dome-shaped seal (1d) of the middle tube of the secondary air feed line (1b), which project through the dome-shaped seal (1d) on one end and project through a baffle plate (1j) on the opposite end; the fuel feed line (2) is arranged concentrically around the secondary air feed line (1), which ends immediately after entering the hot gas zone (21); wherein a first dead volume (4) exists inside the burner between the secondary air feed line (1) and the fuel feed line (2) and wherein the fuel feed line (2) has a nozzle construction (5) on the hot gas side (21), which comprises the following: a ring diaphragm (5a) with holes (5b); radially oriented injector aspiration nozzles (5c), which are in fluid connection with the holes (5b) and, on the aspiration side, project beyond the outer diameter of the primary air feed line (3); wherein the holes (5b) in the ring diaphragm (5a) have an angle of attack of 0?-60?, preferably 10?-45?, more preferably 45?, wherein the ring diaphragm (5a) forms a truncated cone with an angle of attack of 0?-70?, preferably 20?-45?, wherein the base of the cone faces the outer zone (22); a second dead volume (9) is arranged between the secondary air feed line (1) and the fuel feed line (2) on the outer side zone (22); the primary air feed line (3) is arranged concentrically around the fuel feed line (2), which ends immediately after entering the hot gas zone (21) and comprises the following: a conical taper of the diameter at the opening on the hot gas side (21), wherein the conical taper forms a truncated cone with an angle of 0?-20?; an adjustable ring diaphragm (10) at the opening of the conical taper facing the hot gas side (21); swirl vanes (11) with adjustable angle of attack, arranged at an angle of 10? to 90?, preferably 40?-70?.

2. The burner according to claim 2, wherein, the secondary air feed line (1a, 1b, 1c) is adjustable in length, wherein the tube-in-tube system for supplying the secondary air projects with a length L into the combustion chamber, wherein the length L according to the relation L=D*f with D=outer diameter of the primary air feed line and f can have a value of 0?f?3, or projects approx. ? of the secondary air feed line (1) into the hot gas zone (21).

3. The burner according to claim 1, wherein the ratio of ADi:ADm:ADa is approx. 0.7-1.3:1.26-2.34:1.82-3.38, preferably approx. 1:1.8:2.6, wherein ADi represents the outer diameter of the innermost secondary air feed line (1a), ADm represents the outer diameter of the middle secondary air feed line (1b) and ADa represents the outer diameter of the outermost secondary air feed line (1c).

4. The burner according to claim 1, wherein the ratio of IDZ:ADZ is approx. 0.7-1.3:0.98-1.82, preferably approx. 1:1.4, wherein IDZ represents the inner diameter of the fuel feed line (2) and ADZ represents the outer diameter of the fuel feed line (2).

5. The burner according to claim 1, wherein the ratio of IDP:ADP is approx. 0.7-1.3:0.91-1.69, preferably approx. 1:1.3, wherein IDP represents the inner diameter of the primary air feed line (3) and ADP represents the outer diameter of the primary air feed line (3).

6. The burner according to claim 1, wherein the outermost tube of the secondary air feed line (1c) comprises overflow channels (1g), which discharge into the first dead volume (4), and the first dead volume (4) comprises partitions (4a), which reduce the first dead volume, and the ring diaphragm (5a) is adjustable and comprises openings (5d) on the inside.

7. The burner according to claim 1, wherein the radially oriented injector aspiration nozzle (5c) comprises at least one guide plate (5e) with the same orientation as the swirl vane (11) in the primary air feed line(3).

8. The burner according to claim 1, wherein the outermost tube of the secondary air feed line (1c) comprises a nozzle ring (1h) with radially or radially and axially arranged outflow openings at the outlet into the hot gas zone (21).

9. The burner according to claim 1, wherein the cross section of the fuel-filled ring diaphragm (5a) has an outwardly directed cone via which the primary air flows.

10. The burner according to claim 1, wherein holes (5f) are arranged on the inside of the ring diaphragm (5a), which are in fluid connection with the holes in the ring diaphragm (5b).

11. The burner according to claim 1, wherein a feed line for additives (2a) is arranged centrally along the burner axis and projects through the dome-shaped seal of the middle tube of the secondary air feed line (1d), wherein the feed line (2a) comprises a nozzle (2b) in the hot gas zone (21).

12. The burner according to claim 1, wherein the outflow openings of the tube sections (1i) on the side of the baffle plates (1j) can be narrowed by a longitudinally adjustable cone (valve).

13. The burner according to claim 1, wherein an outer annular gap (1k) is formed by two tubes (1m, 1n), which surround the burner on the outside, wherein the inner one of the two tubes (1m) has an opening (1o) and the outer one of the two tubes (1n) has an outlet (1l).

14. A method for the combustion of fuel, wherein, in a burner according to claim 1, secondary air is fed into the secondary air feed line (1), wherein the secondary air is swirled by the swirl vanes (1f); fuel is fed into the fuel feed line (2), wherein the fuel is injected through the holes in the ring diaphragm (5a) at an outwardly directed angle of attack into the swirled primary air; primary air is fed into the primary air feed line (3), wherein the primary air is swirled by the swirl vanes (11); optionally wherein the portion of secondary air is about 20-50% by volume and the portion of primary air may be 50-80% by volume of all air required for combustion.

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

16. The method according to claim 14, wherein the fuel comprises nitrogen compounds, gaseous hydrocarbons, hydrogen, biogas, mixtures of carbon dust and air, hydrogen sulfides, carbon monoxide, mixtures of carbon monoxide and hydrogen, coke-oven gas, tail gas or mixtures thereof.

17. The method according to claim 14, wherein exhaust gases are aspirated into the fuel stream due to the injector effect.

18. The method according to claim 14, wherein the outwardly directed injector aspiration nozzles (5c) are cooled by the outflowing primary air, optionally wherein the aspirated exhaust gas flow is cooled below condensation temperature (dew point) for the exhaust gas humidity inside the injector aspiration nozzles (5c), wherein water is condensed in the exhaust gas flow and the liquid water is fed into the fuel stream.

Description

FIGURES

[0102] FIG. 1 depicts a cross section of a burner of the invention.

[0103] FIG. 2 depicts a cross section of a nozzle construction of the invention.

[0104] FIG. 3 depicts a burner of the invention with an axial outflow of secondary air into the hot gas zone.

[0105] FIG. 4 depicts a three-dimensional view of a burner of the invention.

[0106] FIG. 5 depicts an embodiment of the invention with overflow openings and partitions.

[0107] FIG. 6 depicts a nozzle construction of an embodiment of the invention.

[0108] FIG. 7 depicts another embodiment of the invention with integrated guide plates on the injector aspiration nozzles.

[0109] FIG. 8 depicts yet another embodiment of the invention with a supply line for additives.

[0110] FIG. 9 depicts yet another embodiment of the invention with injector aspiration tubes for mixing in exhaust gas from the combustion chamber into the secondary airstream.

[0111] FIG. 10 depicts yet another embodiment of the invention with an adjustable ring diaphragm in the primary air feed line.

[0112] FIG. 11 depicts a serrated nozzle gap that allows secondary air to flow out both axially and radially in relation to the longitudinal axis.

[0113] FIG. 12 depicts a control concept for regulating the Low NOX burner.

EXAMPLES

Example 1Burner

[0114] A burner according to the invention comprises a hot gas zone 21 and an outer zone 22, a primary air feed line 3, a secondary air feed line 1, a fuel feed line 2, [0115] wherein [0116] the secondary air feed line 1 comprises three concentric cylindrical tubes, an innermost tube 1a, a middle tube 1b and an outermost tube 1c, wherein: [0117] the secondary air feed line 1 protrudes into the hot gas zone 21; [0118] the innermost tube 1a is open to the outer zone 22 and open to the hot gas zone 21; [0119] the middle tube 1b is arranged concentrically around the innermost tube 1a and has a dome-shaped seal 1d, which encloses the innermost tube 1a on the hot gas side 21 dome-like and is closed off towards the outer zone 22; [0120] the middle tube 1b comprises overflow channels 1e, which are arranged in the outer zone 22, comprise holes and are open towards the outermost tube 1c; [0121] the outermost tube 1c is closed off towards the outer zone 22 and open to the hot gas side 21 and comprises adjustable swirl vanes 1f near the opening on the hot gas side 21 at an angle of attack of 40?; [0122] the fuel feed line 2 is arranged concentrically around the secondary air feed line 1, which ends immediately after entering the hot gas zone 21; [0123] wherein a first dead volume 4 exists inside the burner between the secondary air feed line 1 and the fuel feed line 2, and [0124] wherein the fuel feed line 2 has a nozzle construction 5 on the hot gas side 21, which comprises the following: [0125] a ring diaphragm 5a with holes 5b; [0126] radially oriented injector aspiration nozzles 5c, which are in fluid connection with the holes 5b and, on the aspiration side, project beyond the outer diameter of the primary air feed line 3; [0127] wherein the holes 5b in the ring diaphragm 5a have an angle of attack of 45?, [0128] wherein the ring diaphragm 5a forms a truncated cone with an angle of attack of 30?, wherein the base of the cone faces the outer zone 22; [0129] a second dead volume 9 is arranged between the secondary air feed line 1 and the fuel feed line 2 on the side of the outer zone 22; [0130] the primary air feed line 3 is arranged concentrically around the fuel feed line 2, which ends immediately after entering the hot gas zone 21 and comprises the following: [0131] a conical taper of the diameter at the opening on the hot gas side 21, wherein the conical taper forms a truncated cone with an angle of 10?; [0132] an adjustable ring diaphragm 10 at the opening of the conical taper facing the hot gas side 21; [0133] swirl vanes 11 with adjustable angle of attack, arranged at an angle of 55?.

[0134] The secondary air feed line 1a, 1b, 1c is adjustable in length. About ? of the secondary air feed line 1 protrudes into the hot gas zone 21.

[0135] The ratio of outer diameter of the innermost tube 1a of the secondary air feed line:outer diameter of the middle tube 1b of the secondary air feed line:outer diameter of the outermost tube 1c of the secondary air feed line 1 is about 1:1.8:2.6.

[0136] The second dead volume 9 is about ? of the length of the secondary air feed line 1.

[0137] The ratio of inner diameter of fuel feed line 2:outer diameter of fuel feed line 2 is about 1:1.4.

[0138] The ratio of inner diameter of primary feed line 3:outer diameter of primary air fuel line 3 is about 1:1.3.

[0139] The first dead volume 4 has vacuum or thermal insulation.

Example 2Burner with Overflow Channels and Adjustable Nozzle Ring

[0140] The burner as described in example 1 is modified as follows: the outermost tube of the secondary air feed line 1c comprises overflow channels 1g, which end in the first dead volume 4, and the first dead volume 4 comprises partitions 4a, which reduce the first dead volume 4, and the ring diaphragm 5a is adjustable and comprises openings 5d on its inside.

Example 3Burner with Guide Plates

[0141] The burner as described in example 1 or example 2 is modified as follows: the radially oriented injector aspiration nozzle 5c comprises at least one guide plate 5e with the same orientation as the swirl vane 11 in the primary air feed line 3.

Example 4Burner with Nozzle Ring with Radially Oriented Outflow Openings

[0142] The burner as described in any one of the above examples has the following modification: the outermost tube of the secondary air feed line 1c comprises a nozzle ring 1h with radially or radially and axially oriented outflow openings at the outlet into the hot gas zone 21.

Example 5Burner with Tube Segments in the Dome-Shaped Seal

[0143] The burner as described in any one of the above examples has the following modification: tube sections 1i are arranged in the dome-shaped seal 1d of the middle tube of the secondary air feed line 1b, which project through the dome-shaped seal 1d on one end and project through a baffle plate 1j on the opposite end.

Example 6Burner with a Central Additives Feed Line

[0144] The burner as described in any one of the above examples has the following modification: an additives feed line 2a is arranged centrally along the burner axis and projects through the dome-shaped seal of the middle tube of the secondary air feed line 1d, wherein the feed line 2a comprises a nozzle 2b in the hot gas zone 21.

Example 7Method

[0145] In a burner as described in any one of the examples 1 to 6, secondary air is fed into the secondary air feed line 1, wherein the secondary air is swirled by the swirl vanes 1f; fuel is fed into the fuel feed line 2, wherein the fuel is injected through the holes in the ring diaphragm 5a at an outwardly directed angle of attack into the swirled primary air; primary air is fed into the primary air feed line 3, wherein the primary air is swirled by the swirl vanes 11.

[0146] The portion of secondary air is 40% by volume and the portion of primary air is 60% by volume of all air required for combustion.

[0147] The total air coefficient for the sum of primary and secondary air ? is about 1.1.

[0148] The primary air and secondary air are a mixture of air and exhaust gas.

[0149] The fuel is natural gas.

[0150] Exhaust gas is directly aspirated into the fuel stream due to the injector effect.

[0151] The outwardly directed injector aspiration nozzles 5c are cooled by the outflowing primary air.

[0152] The quantities of material flows are controlled on the basis of a rigidly functioning programmed logic for low NOx and CO emissions.