REGENERATIVE BURNER FOR STRONGLY REDUCED NOx EMISSIONS

Abstract

The invention relates to a burner with a refractory burner body 1, 2, 3 for burning liquid or aerosol fuels, in particular, gaseous fuels. With the aim of reducing NO.sub.x emissions, the burner body comprises a gas nozzle 7, 9, 10, 11 and a plurality of air nozzles 4, 6, which are at least partially formed as integral mouldings in the burner body and flow out on a front side 16 of the burner body. Here, the air nozzles are symmetrically arranged around the gas nozzle and diverge at an angle to the gas nozzle. Likewise, the invention relates to a method for burning liquid or aerosol fuels, in particular, gaseous fuels with reduced NO.sub.x emissions.

Claims

1. Burner with a refractory burner body for burning liquid or aerosol fuels, in particular, gaseous fuels. wherein the burner body comprises a gas nozzle and a plurality of air nozzles which are at least partially formed as integral mouldings in the burner body and flow out on a front side side of the burner body. wherein the air nozzles are arranged symmetrically around the gas nozzle and diverge at an angle of the gas nozzle.

2. Burner according to claim 1, wherein the angle is between 1 and 45 degrees.

3. Burner according to claim 1, wherein the burner body comprises two to eight, preferably four, air nozzles.

4. Burner according to claim 1, wherein the air nozzles comprise outlet openings with a total surface that is not more than half of a circular surface of the front side of the burner body.

5. Burner according to claim 1, wherein the air nozzles comprise outlet openings, the widths of which grow radially from the gas nozzle.

6. Burner according to claim 1, wherein the gas nozzle comprises a pre-combustion chamber which is formed in the burner body, and at least one air nozzle comprises a pre-combustion air nozzle, which connects the air nozzle to the pre-combustion chamber.

7. Burner according to claim 1, wherein the gas nozzle comprises a swirl nozzle for swirling the fuel, which is used in the burner body.

8. Burner according to claim 1, wherein the burner body is formed by a first quarl with the front side, a second quarl, which is arranged coaxially to the first quarl, and a third quarl with a burner orifice and is designed as an outer shell of the first and second quarl.

9. Method for burning liquid or aerosol fuels, in particular, gaseous fuels with reduced NO.sub.x emissions, wherein the following steps are performed: providing a gaseous fuel; providing a gas mixture with oxygen and nitrogen, in particular air suitable for the oxidation of the fuel; emitting and igniting the gaseous fuel into a gas flame; and emitting the gas mixture in at least two directions, each of which diverges at a certain angle to the gas flame.

10. Method according to claim 9, wherein, when emitting and igniting the gaseous fuel, such a partial volume of the gas mixture is provided to the fuel to burn a certain percentage of the fuel.

11. Method according to claim 9, wherein the gaseous fuel is swirled and/or rotated before being emitted.

12. Method according to claim 9, wherein the at least two directions are spaced away at the same distance to one another and have the same angle around the gas flame.

Description

[0039] The figures described below refer to preferred exemplary embodiments of the burner according to the invention, wherein these figures do not serve as a limitation, but essentially serve as an illustration of the invention. Elements from different figures, but with the same reference numbers are identical; therefore, the description of an element from one figure is also valid for equal or numbered elements from other figures.

[0040] The figures show:

[0041] FIG. 1 a cross-section through a burner in accordance with a preferred exemplary embodiment; and

[0042] FIG. 2 a top view of the front side of the burner in FIG. 1.

[0043] In FIG. 1, the burner 15 according to the invention is shown, which comprises a burner body, which is formed by a first quarl 1, a second quarl 2 and a third quarl 3. All three quarls 1, 2, 3 are individual parts of the burner body and abut each other. The first and second quarl 1, 2 are cylindrical and the third quarl 3 is hollow cylindrical in shape, wherein the first and second quarl 1, 2 are arranged in the third quarl 3. For this purpose, the arrangement can be precise or, if there are dimensioning inaccuracies, be implemented or provide support by means of insulating wool and/or refractory paper/wool between the quarls. For a predetermined alignment of the three quarls 1, 2, 3 to each other, these groove/spring devices can comprise rails and/or attachments or elevations and recesses, thereby making a targeted or predetermined composition of the quarls possible.

[0044] The burner 15 shown is equipped with a gas nozzle and four air nozzles. In this case, the gas nozzle preferably comprises the following components, which are arranged sequentially and coaxially or along a longitudinal axis 14 to each other: a hollow-cylindrical outlet nozzle 11 made of metal, which is supplied with gas via a feed line 12; a swirl nozzle 9 for swirling the gas, which is used in the second quarl 2; a tubular mixing path 10, through which the swirled gas is passed; a pre-combustion chamber 7, into which the mixing path 10 as well as four pre-combustion air nozzles or conduits 5 of the air nozzles flow. In this pre-combustion chamber 7, the swirled gas is mixed with the air from the pre-combustion air nozzles 5 and preferably initially ignited. The mixing path 10 and the pre-combustion chamber 7 are formed as a single piece in the first quarl 1. The swirl nozzle 9 is located at the transition from the second quarl 2 to the first quarl 1. In this case, the swirl nozzle 9 can be created in such a way that no gases from the (boundary) layer between the first and second quarl 1, 2 can enter into the gas nozzle; i.e. the outer side of the swirl nozzle 9 preferably seals the gas nozzle against unwanted gases or against gas leaks. The outlet nozzle 11 is arranged in a cavity in the second quarl 2, wherein the gas supply 12 is arranged in a cooling line 13, which feeds for cooling the feed line 12 and the outlet nozzle 11 preferably cooled air. This prevents premature ignition of the gas due to elevated temperatures, especially before the gas enters the swirl nozzle 9. In addition, the air of the cooling line 13 protects the metallic components of the burner. In other embodiments, a burner may comprise a plurality of gas-feed and cooling-air lines. Each air nozzle preferably has the following components: an air conduit 4, which is formed in the second quarl 2; a main combustion air nozzle or conduit 6, which is formed in the first quarl 1 and connected to the air conduit 4; as well as a pre-combustion air nozzle or conduit 5, which is also formed in the first quarl 1 and branches off from the main burner air nozzle 6 into the pre-combustion chamber 7. Thus, except for the outlet nozzle 11, the feed line 12 and the swirl nozzle 9 all other, in particular mentioned above components of the burner 15 in the quarls 1, 2, 3 are formed by cavities.

[0045] In FIG. 1, the angle between the longitudinal axis 14 (or also the gas nozzle) and an air nozzle is drawn, which indicates the air flow diverging to an emanating gas or a gas flame. In this case, the conduit 4 and the main combustion nozzle 6 are formed to be identical to each other and form a conduit with a constant shape, thickness and width from the back of the burner 15 to the front side 16 of the burner 15. The angle is formed, in particular, between the longitudinal axis 14 and the inner side or inner edge of the air conduit 4 or the main combustion nozzle 6. In other embodiments, the conduit 4 and the nozzle 6 may differ; in this case, other components, such as the outlet opening of the air nozzle, in particular, the main combustion air nozzle 6 at the front side, can be formed in such a way that the air is emitted at an angle of the longitudinal axis 14.

[0046] Preferably, the burner body or at least one or all of the quarls 1, 2, 3 is refractory. The first quarl 1 comprises a circular front side/surface 16 and the third quarl 3 comprises a burner orifice 8 enlarging in the shape of a funnel. In particular, these components 16, 8 as well as the pre-combustion chamber 7 are designed to be at least refractory; or alternatively formulated, components that stand up against the combustion or gas flame and/or are subjected to the heat/radiation thereof. The four main combustion air nozzles 6 and the pre-combustion chamber 7 flow out on the front side 16. Thereby, these components form openings or outlet surfaces, which are arranged symmetrically around the longitudinal axis 14.

[0047] The cross-section shown in FIG. 1 through the burner 15 according to the invention takes place at a certain angle, less than 180 degrees along the longitudinal or symmetry axis 14. Thus, both the gas supply conduit of the gas nozzle as well as the air conduit 4 is visible for the air supply of the air nozzle; ultimately, four air nozzles are formed symmetrically and would not show the cooling-air line 13 with the feed line 12 in the case of a straight cross-sectional area in contrast to the surfaces shown at an angle to one another. Air nozzle and gas nozzle or their conduits are separated from each other in the second and third quarl 2, 3.

[0048] In FIG. 2, the burner 15 in FIG. 1 is shown in a top view. In this case, in particular, the circular front side/surface 16 of the first quarl 1 and the annular burner orifice 8 of the third quarl 3 is shown. In the centre of the front side 16, through which the longitudinal axis of the burner 15 passes, the partial pocket hole of the pre-combustion chamber 7 is formed with the subsequent mixing path 10 and the swirl nozzle 9. The pre-combustion chamber 7 is a partial blind hole, since it does not completely terminate with the exception of an annular bottom. On the ground, the four openings to the pre-combustion air nozzles 5 are each arranged at a 90-degree angle towards each other around the centre point or the longitudinal axis.

[0049] The four openings of the main combustion air nozzles 6 are radially aligned from the longitudinal axis of the burner 15, in particular, cross-shaped and identical to the four pre-combustion air nozzles 5. It is noted that the area of an outlet opening of the main combustion air nozzle 6 is the same size and/or shaped as the cross-section of the main combustion air nozzle 6 within the first quarl 1. In other embodiments, the outlet openings and their connected conduits, such as the main combustion air nozzles 6, the pre-combustion air nozzle 5 and the air conduits 4, can differ in their shape and/or size. The openings shown each form a trapezoidal surface, which tapers toward the longitudinal axis or widens towards the outer circumference of the burner 15. Instead of the trapezoidal shape, other shapes of the plate are possible in other embodiments.

REFERENCE LIST

[0050] 1 first quarl, front side of the burner [0051] 2 second quarl. rear side of the burner [0052] 3 third quarl, outer shell of the burner [0053] 4 air conduit [0054] 5 pre-combustion air nozzle/conduit [0055] 6 main combustion-air nozzle/conduit [0056] 7 pre-combustion chamber [0057] 8 burner orifice [0058] 9 swirl nozzle [0059] 10 mixing path [0060] 11 outlet nozzle [0061] 12 gas-nozzle feed line [0062] 13 cooling-air line [0063] 14 (symmetry) axis [0064] 15 burner [0065] 16 front side/surface of the burner, in particular, of the first quarl.