DE102012022767B4 - Burner head for a gas or oil burner - Google Patents

Abstract

Burner head (1) for a gas or oil burner, which has a burner plate (2) with a burner surface (7) and a lower side (6), wherein in the burner plate (2) outlet openings (3, 4, 5) for a fuel Are formed on the underside (6) of the burner plate (2) at least two webs (13, 14), the burner plate (2) in a central region (17) and in two edge regions (15, 16 ), characterized in that on the underside (6) of the burner plate (2) an antechamber (10) is formed, in which the webs (13, 14) protrude, wherein a distance D from parallel to the longitudinal direction extending side walls (8 , 9) of the antechamber (10) is greater than a distance d from parallel to the longitudinal direction extending boundary walls (18, 19) of an upstream of the antechamber (10) arranged feed region (12), wherein the feed region (12) and the prechamber (10). connected via a transition region (11) they are.

Description

The invention relates to a burner head for a gas or oil burner according to the preamble of patent claim 1.

This burner head has a burner plate with a burner surface and a lower side, wherein in the burner plate outlet openings for a fuel-air mixture are formed. As fuel usually gas is used, whereby the use of other fuels, such as oil, is possible. The fuel-air mixture then flows from the bottom of the burner plate through the outlet openings, is ignited at the burner surface and burns with flame formation. The underside is not necessarily arranged geodetically below the burner surface, but is always located upstream of the burner surface.

Such burners are used, for example, for domestic hot water preparation, ie for heating water via a heat exchanger, via which the heat released during combustion heat is dissipated. The need for heat is relatively variable, so that the burner is operated with different firing rates.

The setting of the firing capacity is usually done by controlling the amount of fuel supplied or by setting a certain fuel-air ratio. However, this can lead to instabilities in flame formation. In particular, when a maximum firing capacity is required, the flames can be lifted off the burner surface. This leads to an unclean combustion and increased pollutant emissions. In particular, this can lead to the release of carbon monoxide (CO).

For example, to achieve a stable flame formation at the burner surface JP 2005 049 055 A known to provide openings in addition to the outlet openings in the burner plate in perpendicular side walls of the burner head, through which the fuel-air mixture can flow. As a result, the fuel-air mixture flows out of the burner head at different speeds. Small flames form on the side next to the central flames, which hold the central flames at the burner surface, so to speak, and thus prevent lifting even at high firing rates.

The burner plate may have a vertically projecting web in the region of the outlet openings, which increases the stability of the burner plate and thus of the burner head and serves to dissipate heat from the burner surface. The dissipated heat is released from the web to the inflowing fuel-air mixture, which is thereby preheated.

The openings arranged perpendicular to the actual flow direction in the side walls of the burner head require additional, lateral flow channels and, accordingly, a relatively large amount of space. Also, the formation of flame can exceed the actual burner surface, so that a defined flame formation is not always guaranteed.

A similar burner head is in US 2008/01 60 467 A1 proposed, wherein laterally adjacent to the burner plate additional air ducts are arranged, is discharged through the air above the burner plate. Thus, a second flame can be generated above the flame formed on the burner surface, by which a complete combustion is to be ensured.

The disadvantage of these solutions is that they require a relatively large amount of space and are expensive to produce. In this case, a flame is not only on the burner surface of the burner plate, whereby a defined flame formation does not always seem to be guaranteed.

Other already known burners are in the publications DE 195 411 5 C3 . JP H09-203 509 A . JP H06-193 834 A . JP H06-193 832A . WO 2009/094 791 A2 and DE 10 2009 058 453 A1 shown.

The invention has for its object to ensure a stable flame formation with low pollutant emissions at different Feuerungsleistungen, the burner head with little effort and should therefore be inexpensive to produce. In this case, even at different flow rates of the fuel-air mixture, the carbon monoxide and nitrogen oxide emissions are kept low and a lifting of the flame from the burner surface can be avoided.

According to the invention this object is achieved with the features of claim 1. Advantageous developments can be found in the dependent claims.

The invention is characterized in that at least two webs are arranged on the underside of the burner plate, which divide the burner plate into a central region and into two edge regions.

The burner surface is divided by the webs into three areas, each with its own flame formation, wherein the fuel-air mixture can emerge at different exit velocities through the outlet openings. By the side flames ("holding flames") can be done anchoring the central flame, so that a lifting of the flames is not to be feared even at maximum firing capacity and correspondingly high flow rate. In this case, carried by the webs a temperature dissipation from the burner surface, wherein the heat absorbed at the burner surface is discharged at the bottom or directly from the webs to the inflowing fuel-air mixture, thereby preheated exits through the outlet openings of the burner plate and then ignited , This also leads to a more stable combustion.

In a further development of the burner head, the webs run parallel to a longitudinal direction of the burner plate and in particular perpendicular to the burner plate. The burner plate is divided on its underside by the webs, so to speak in three longitudinal strips which extend parallel to each other from one narrow side to the other narrow side. By a vertical arrangement of the webs in relation to the burner plate, these have only a low flow resistance.

According to a further embodiment, the outlet openings have a first hole geometry in the middle region and a second hole geometry in the edge regions, the middle region being formed with a larger opening area ratio than the edge regions. The area ratio of the open passage cross-section to the respective burner surface area is thus greater in the central area than in the edge areas. By means of this embodiment, it is achieved that the essential part of the fuel-air mixture emerges through the outlet openings of the middle region, so that a large flame is formed there. In contrast, only small flames (holding flames) are to be formed in the edge regions, by means of which anchoring of the middle flames to the burner surface is achieved. By appropriate design of the hole geometries can thus ensure a stable flame formation.

This is further assisted if an area of the middle area is larger than a sum of the areas of the edge areas. The greater part of the burner surface is then formed by the middle region.

In a preferred embodiment, the outlet openings are formed in the middle region as slots which extend transversely to the longitudinal direction of the burner plate, wherein the outlet openings are formed in the edge regions as longitudinally extending slots or as circular openings. As a result, different exit speeds of the fuel-air mixture are achieved, wherein the essential part of the fuel-air mixture exits through the central region located in the outlet openings, which are formed as transverse to the longitudinal direction of the burner plate slots. Even with different firing rates and in particular different flow rates and exit velocities, a stable flame formation is achieved. The outlet openings formed in the edge regions stabilize the middle flame and at the same time reduce the pressure so that a total flame height is reduced.

According to the invention, an antechamber is formed on the underside of the burner plate, in which the webs protrude, wherein a distance D from parallel to the longitudinal direction, and in particular perpendicular to the burner plate, extending side walls of the prechamber is greater than a distance d from parallel to the longitudinal direction, and in particular perpendicular to the burner plate, extending boundary walls of a feed chamber arranged upstream of the antechamber, wherein the feed region and the antechamber are connected to one another via a, in particular funnel-shaped, transition region. A flow rate of the incoming fuel-air mixture is thereby reduced in the pre-chamber, so that the fuel-air mixture emerges from the outlet openings at reduced speed. The lateral increase in volume results in a stronger reduction of the flow velocity in the edge regions, so that the fuel-air mixture in the edge region at a slower speed emerges than in the middle Be-rich. This is further aggravated by the fact that due to the sudden widening during the transition from the feed region into the pre-chamber, side turbulences occur, by means of which the fuel-air mixture flowing to the edge regions is further braked. In this case, by means of the webs formed on the underside of the burner plate, a relatively early separation of the fuel-air mixture into three subsets occurs, wherein the outer subsets flow into the peripheral regions and the middle subset into the central region and exit through the respective outlet openings. As a result, a relatively large difference in speed between the edge regions and the central region can be realized.

Preferably, a ratio of the distances D to d is in the range between 1.6 and 2 and is in particular 1.8. Such a widening during the transition from the feed region into the pre-chamber results in an optimal deceleration of the flow velocity with a good turbulence in the Edge areas, so that a high speed difference between the central area and the edge areas is obtained.

Advantageously, the webs have a height L1, wherein the feed region terminates at a distance L2 to the burner plate and a ratio of the distance L2 to the height L1 between 1.6 and 2, in particular 1.8. This ensures that, on the one hand, sufficient space is available for forming the turbulences and for flowing the fuel-air mixture into the edge regions, and on the other hand, relatively fast mutual interference of the three subsets of the fuel-air mixture is prevented.

In a preferred embodiment, the webs are arranged approximately in alignment with the boundary walls of the feed region. The volume expansion extends so to speak only on the edge areas. This ensures that the essential part of the fuel-air mixture passes without deflection directly into the central region and can escape through the local outlet openings. The webs thus form only a low flow resistance.

In order to achieve a good mixing of the fuel with the air, the supply region may be connected upstream with a particular V-shaped feed channel for the fuel-air mixture, which is optionally formed as a Venturi tube.

The burner head can be bent integrally from a metal sheet, the burner plate is obtained with the webs and optionally the side walls and the boundary walls by punching, stamping and bending of the metal sheet. In the region of the webs, the metal sheet is then double, so that a good stabilization of the burner head is achieved and sufficient material for the dissipation of heat from the burner surface is available. In this case, the burner head can be produced very inexpensively, wherein in particular by the one-piece design no temperature-sensitive seams are generated.

• 1 einen Brennerkopf in dreidimensionaler Darstellung,
• 2 einen Gasbrenner mit montierten Brennerkopf,
• 3a eine erste Variante der Brennerplatte,
• 3b eine zweite Variante der Brennerplatte,
• 4 eine schematische Darstellung der Flammenbildung,
• 5 einen Querschnitt des Brennerkopfes mit Strömungslinien.

The drawing illustrates an embodiment of the invention and is shown in FIG

• 1 a burner head in three-dimensional representation,
• 2 a gas burner with mounted burner head,
• 3a a first variant of the burner plate,
• 3b a second variant of the burner plate,
• 4 a schematic representation of the flame formation,
• 5 a cross section of the burner head with flow lines.

In 1 you recognize a burner head 1 for a gas or oil burner, which is provided with a burner plate 2, in the outlet openings 3 . 4 . 5 are designed for a fuel-air mixture. Through the outlet openings is a bottom 6 the burner plate 2 with a burner surface 7 connected.

Laterally to the burner plate 2 Close sidewalls 8th . 9 at, which extend perpendicular to the burner plate 2 and together with the bottom 6 an antechamber 10 form. The antechamber 10 is over a funnel-shaped transition area 11 connected to a feed region 12, through which a fuel-air mixture to the burner head 1 can be supplied.

On the bottom 6 the burner plate 2 are two bars 13 . 14 formed, which are perpendicular to the burner plate 2 and in the longitudinal direction of the burner plate 2 extend. By the webs 13, 14, the burner plate 2 in two border areas 15 . 16 and a middle area 17 divided. A corresponding subdivision also results for the largest part of the antechamber 10 ,

The middle area 17 extends over a similar large or larger area than the edge regions 15, 16. The outlet openings 4 of the middle area 17 are formed by slots which are perpendicular to the longitudinal direction of the burner plate 2 extend. In the edge regions 15, 16 are the outlet openings 3 . 5 shaped as round openings. This ensures that most of the fuel-air mixture is supplied by the mid-range 17 trained outlet openings 4 exit and a big flame on the burner plate 2 or the burner surface 7 generated.

The incoming fuel-air mixture is in the antechamber 10 slowed down due to the volume increase, as are the sidewalls 8th . 9 are further apart than the boundary walls 18 . 19 of the feed area 12 , In the transition area 11 or at the beginning of the antechamber 10 this swirling occur, so that the fuel-air mixture in the peripheral areas 15 . 16 at a slower rate than in the middle range 17 ,

Through the burner head 1 becomes the burner surface 7 divided into three areas, the middle area 17 , in which the main flames are produced, and in the border areas 15 . 16 , in which smaller (holding) flames are created, which serve to anchor the flame of the central region. This ensures a stable flame formation with low carbon monoxide and nitrogen emissions even with different firing rates, and a lifting of the flames is reliably avoided even at high firing rates.

In 2 is a burner head 1 in connection with a feed channel 20 represented, which is V-shaped and formed as a Venturi tube. In the feed channel 20 a good mixing of the fuel-air mixture takes place before it passes through the feed area 12 in the antechamber 10 passes and through the outlet openings 3 . 4 . 5 exit. Finally, combustion takes place at the burner surface 7.

3a shows a first variant of the burner plate 2 in which the outlet openings 3 . 5 that are in the border areas 15 . 16 are formed, are formed as circular openings. The middle range 17 arranged outlet openings 4 are formed as slots which are transverse to the longitudinal direction of the burner plate 2 run. In this case, the outlet openings 4 have different lengths, in each case a plurality of outlet openings 4 are combined in groups. The slots 4 are symmetrical to a center line of the burner plate 2 educated.

In 3b is a variant of the burner plate 2 shown facing the in 3a variant shown by the hole geometry of the outlet openings 3 . 5 in the border areas 15, 16 differs. These are formed in this embodiment as longitudinally extending slots.

In 4 schematically a flame image is shown in cross section. Above the central region 17 forms a main flame 21 out by lateral (holding) flames 22 . 23 extending over the edge areas 15 . 16 train, at the burner surface 7 is held. This flame pattern is maintained even with different firing rates and thus different flow rates, which even at high flow rates and high exit velocity of the fuel-air mixture, a lifting of the flames is prevented.

5 shows a cross section of the flow cross sections of the burner head 1 (The burner head itself is not shown), in which flow lines are shown, which should represent the flow behavior of the fuel-air mixture. The fuel-air mixture passes through the feed area 12 over the transition area 11 into the antechamber 10. Due to the sudden flow cross-section increase form in the edge region of the transition region 11 Turbulences resulting in a slowing of the flow velocity in the peripheral areas 15 . 16 to lead. Between the bridges 13 . 14 and the respective side wall 8th . 9 the fuel-air mixture thus flows with a reduced flow velocity in relation to the central region 17 between the bridges 13 . 14 , These features create a sturdy burner that forms a stable flame even when the fuel-air mixture changes.

The bridges 13 . 14 extend by a length L1 from the bottom 6 the burner plate 2 starting in the antechamber 10 into it. The feed area 12 ends at a distance L2 to the burner plate 2 , A ratio of L2 to L1 is about 1.8, so there is sufficient space available to allow the fuel-air mixture to reach the margins 15 . 16 can get.

A distance D between the side walls 8th . 9 the antechamber 10 is about 1.8 times larger than a distance d of the boundary walls 18 . 19 in the feed area 12 , By increasing the distance of the side walls results in an increase in volume and thus a slowing down of the fuel-air mixture. Here are the bars 13 . 14 formed in alignment with the boundary walls 18, 19, whereby it is achieved that the flow rate is only slightly slowed down in the central region, while in the edge regions 15, 16 a greater decrease in speed takes place. As a result, the fuel-air mixture emerges at a higher speed in the central region than in the peripheral regions.

The burner head according to the invention results in stable flame formation even with different firing capacities of the burner. In this case, different exit speeds of the fuel-air mixture are achieved by the burner plate is divided by at least two webs in a central region and two edge regions. In the edge areas so small flames are formed, which hold the large flames formed in the central region of the burner surface. By a more or less sudden cross-sectional expansion (volume increase) in the antechamber lateral turbulence caused, whereby the flow velocity in the edge regions is further reduced. This can be formed in the marginal areas very small flames. The arrangement of the outlet openings in the edge regions and in the middle region of the burner surface ensures that the flames interact with one another and, in particular, thermochemical and fluid-dynamic compensation processes occur. This results in a very stable flame formation. This is further enhanced by the fact that by the webs, which divide the burner plate in a central region and two edge regions, also a dissipation of heat from the burner surface, that is, a cooling of the burner surface and the flame takes place and a preheating of the supplied fuel-air Mixture.

Overall, the burner head according to the invention enables stable flame formation with different firing rates and low emissions, in particular of carbon monoxides and nitrogen oxides, wherein a lifting of the flames from the burner surface is prevented even at high firing rates.

LIST OF REFERENCE NUMBERS

1

burner head

3

outlet openings

5

outlet openings

7

burner surface

9

Side wall

11

Transition area

13

web

15

border area

17

middle area

19

boundary wall

21

main flame

23

lateral flame

2

burner plate

4

outlet openings

6

bottom

8th

Side wall

10

antechamber

12

feeding

14

web

16

border area

18

boundary wall

20

feed

22

lateral flame

Claims (11)

Burner head (1) for a gas or oil burner, which has a burner plate (2) with a burner surface (7) and a lower side (6), wherein in the burner plate (2) outlet openings (3, 4, 5) for a fuel Are formed on the underside (6) of the burner plate (2) at least two webs (13, 14), the burner plate (2) in a central region (17) and in two edge regions (15, 16 ), characterized in that on the underside (6) of the burner plate (2) an antechamber (10) is formed, in which the webs (13, 14) protrude, wherein a distance D from parallel to the longitudinal direction extending side walls (8 , 9) of the antechamber (10) is greater than a distance d from parallel to the longitudinal direction extending boundary walls (18, 19) of an upstream of the antechamber (10) arranged feed region (12), wherein the feed region (12) and the prechamber (10). via a transition area (11) verbu together are. Burner head after Claim 1 , characterized in that the webs (13, 14) parallel to a longitudinal direction of the burner plate (2) and in particular perpendicular to the burner plate (2). Burner head after Claim 1 or 2 , characterized in that the outlet openings (3, 4, 5) in the central region (17) have a first hole geometry and in the edge regions (15, 16) has a second hole geometry, wherein the central region (17) is formed with a larger opening area ratio as the edge regions (15, 16). Burner head according to one of the preceding claims, characterized in that a surface of the central region (17) is greater than a sum of the surfaces of the edge regions (15, 16). Burner head according to one of the preceding claims, characterized in that the outlet openings (4) in the central region (17) are formed as slots which extend transversely to the longitudinal direction of the burner plate (2), wherein the outlet openings (3, 5) in the edge regions ( 15, 16) are formed as longitudinally extending slots or as circular openings. Burner head according to one of the preceding claims, characterized in that the side walls (8, 9) and / or the boundary walls (18, 19) perpendicular to the burner plate (2) and / or that the transition region (11) is funnel-shaped. Burner head according to one of the preceding claims, characterized in that a ratio of the distances D / d in the range between 1.6 and 2, in particular 1.8. Burner head according to one of the preceding claims, characterized in that the webs (13, 14) have a height L1, wherein the feed region (12) terminates at a distance L2 to the burner plate (2) and a ratio of the distance L2 to the height L1 is between 1.6 and 2, in particular 1.8. Burner head according to one of the preceding claims, characterized in that the webs (13, 14) are arranged approximately in alignment with the boundary walls (18, 19) of the feed region (12). Burner head according to one of the preceding claims, characterized in that the feed region (12) is connected upstream with a particular V-shaped feed channel (20) for the fuel-air mixture, which is optionally formed as a Venturi tube. Burner head according to one of the preceding claims, characterized in that the burner plate (2) with the webs (13, 14) and optionally the side walls (8, 9) and the boundary walls (18, 19) is integrally bent from a metal sheet.

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