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. A burner comprising: a refractory burner body for burning gaseous fuel, the refractory burner body comprising a front side and a back side, the front side consisting of a gas nozzle and a plurality of air nozzles that are formed in the refractory burner body, wherein the gas nozzle comprises at least one exit orifice shaped to eject the gaseous fuel in a direction parallel to a longitudinal axis of the gas nozzle, and each of the plurality of air nozzles eject air and are arranged symmetrically around the longitudinal axis of the gas nozzle, each of the air nozzles are arranged and formed to diverge with respect to each other, and each of the air nozzles being angled with respect to the longitudinal axis of the gas nozzle such that all of the air is ejected through each of the air nozzles that are angled, and wherein each of air nozzles comprise an outlet opening having a width that grows radially from the gas nozzle, wherein the outlet opening for each of the air nozzles forms a trapezoidal outlet surface on the front side of the burner body, the trapezoidal outlet surface tapers toward the longitudinal axis of the gas nozzle and widens towards an outer circumference of the burner, wherein the gas nozzle comprises a pre-combustion chamber which is formed in the refractory burner body, and at least one of the air nozzles comprises a pre-combustion air nozzle which connects the at least one air nozzle to the pre-combustion chamber and wherein the refractory burner body is formed by a first quarl with the front side and wherein the pre-combustion chamber and the pre-combustion air nozzle are formed in the first quarl, wherein the refractory burner body is formed by 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 and wherein the second quarl includes a plurality of air conduits and the first quarl includes the plurality of air nozzles connected to the plurality of air conduits.

2. The burner according to claim 1, wherein the gas nozzle comprises an atomizer.

3. The burner according to claim 1, wherein each the air nozzles comprises an orifice or frame tapering towards an outer surface of the burner orifice.

4. The burner according to claim 1, wherein the pre-combustion air nozzle is radially aligned with the at least one of the air nozzles.

5. The burner according to claim 1, further comprising a tubular mixing path through which the gaseous fuel is swirled and passed prior to combustion.

6. The burner according to claim 5, wherein the tubular mixing path is formed in the first quarl.

7. The burner according to claim 1, wherein each of the air nozzles is angled at an angle a between 1 and 45 degrees relative to the longitudinal axis of the gas nozzle.

8. The burner according to claim 1, wherein the plurality of air nozzles comprises two to eight air nozzles.

9. The burner according to claim 1, wherein all outlet openings for the air nozzles have a total area that is not more than half of a circular surface of the front side of the refractory burner body.

10. The burner according to claim 8, wherein the plurality of air nozzles comprises four air nozzles.

11. The burner according to claim 1, wherein each of the air nozzles extend fully through the refractory burner body.

12. The burner according to claim 7, wherein the angle is 4 degrees relative to the longitudinal axis of the gas nozzle.

Description

(1) 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.

(2) The figures show:

(3) FIG. 1 a cross-section through a burner in accordance with a preferred exemplary embodiment; and

(4) FIG. 2 a top view of the front side of the burner in FIG. 1.

(5) 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.

(6) 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.

(7) 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.

(8) 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.

(9) 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.

(10) 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.

(11) 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

(12) 1 first quarl, front side of the burner 2 second quarl. rear side of the burner 3 third quarl, outer shell of the burner 4 air conduit 5 pre-combustion air nozzle/conduit 6 main combustion-air nozzle/conduit 7 pre-combustion chamber 8 burner orifice 9 swirl nozzle 10 mixing path 11 outlet nozzle 12 gas-nozzle feed line 13 cooling-air line 14 (symmetry) axis 15 burner 16 front side/surface of the burner, in particular, of the first quarl.