The present invention pertains to an atomizing nozzle for a burner, especially for a vehicle heater, comprising a flow guide element, which provides a flow guide surface and which has an atomizing lip in an end area, as well as a fuel feed device for feeding fuel to the flow guide surface at a spaced location from the atomizing lip.
An atomizing nozzle as used in combustion chambers of gas turbines used as aircraft engines is known from EP 0 910 776 B1. The air stream entering the gas turbine is split in this prior-art atomizing nozzle. Part of the air fed in is introduced into an atomizing nozzle in the form of an outer swirling flow and an inner swirling flow. A flow guide element separates the outer swirling flow from the inner swirling flow and also forms, in particular, a flow guide surface, which ends in an atomizing lip in an axial end area of the flow guide element, for the inner swirling flow. The fuel is injected by an injection nozzle arranged centrally in relation to the flow guide element onto the above-mentioned flow guide surface through the inner swirling flow moving along the said flow guide surface and it then moves along the said flow guide surface in the direction of the atomizing lip. When the fuel film formed by injection on the flow guide surface for the inner swirling flow reaches the atomizing lip, it is atomized by the shear flow present in the area of the atomizing lip. Together with the combustion air fed in by the outer swirling flow and the inner swirling flow, the atomized fuel flows into the combustion chamber, where it is also burned while combining with the air led first past the atomizing nozzle.
The object of the present invention is to provide an atomizing nozzle for a burner as can be used especially in a vehicle heater, which leads to improved combustion of the fuel introduced.
According to a first aspect of the present invention, this object is accomplished by an atomizing nozzle for a burner, especially for a vehicle heater, comprising a flow guide element, which provides a flow guide surface and which has an atomizing lip in an end area, as well as a fuel feed device for feeding fuel to the flow guide surface at a spaced location from the atomizing lip.
Provisions are, furthermore, made according to the present invention for the fuel feed device in the flow guide element to have a fuel release depression, into which opens a fuel feed channel device in a junction area.
By feeding the fuel directly onto the flow guide surface in the atomizing nozzle according to the present invention while avoiding passing the fuel being fed through the air flowing along the flow guide surface, markedly better quality of the fuel atomization is achieved, because it can be avoided that fuel particles are carried during their passage by the air flowing through the atomizing nozzle without being led over the flow guide surface to the atomizing lip. More uniform distribution of the fuel to be atomized on the flow guide surface can also be achieved in this manner in the area located in front of the atomizing lip.
To make the distribution of the fuel to be atomized onto the flow guide surface even more uniform, it is proposed that at least one fuel distribution element be provided in the fuel release depression for delivering fuel being fed into the fuel release depression by means of the fuel feed channel device to areas of the fuel release depression that are located farther away from the junction area. Provisions may be made here, e.g., for the fuel distribution element to be designed with the utilization of the capillary effect to deliver the fuel.
A capillary flow can be achieved, using even comparatively insensitive components or materials, e.g., by the fuel distribution element defining a capillary flow channel device in cooperation with a surface area defining the fuel release depression in the flow guide element.
Furthermore, it is proposed that the fuel distribution element have at least one fuel passage area to make possible the discharge of the fuel from the fuel release depression. The fuel distribution element may comprise at least one elongated element, e.g., one made of wire material, extending along the fuel release depression. In addition, it is possible in an advantageous variant for the fuel distribution element to have a plurality of elongated elements that are located adjacent to one another and form a capillary flow channel device between them. The individual elongated elements, which can be considered to be strands of a composite of an, e.g., braided design, inherently form, especially if they have a round cross section, very fine channels between them, via which the fuel can then be delivered away from the junction area.
As an alternative, it is also possible for the at least one fuel distribution element to be formed from a porous material.
The junction area preferably has at least one junction site, at which a fuel feed channel section of the fuel feed channel device opens into the depression. To allow a certain predistribution to take place here, it is, of course, possible to provide a plurality of junction sites distributed along the fuel release depression.
It is proposed, furthermore, that the junction area be provided in a bottom area of the fuel release depression that defines the fuel release depression essentially radially. To impart a certain flow component in the longitudinal direction of the fuel release depression during its introduction into the fuel release depression and thus to further improve the distribution of the fuel over the length of the fuel release depression, it is proposed that the fuel feed channel device comprise at least one fuel feed channel section opening essentially tangentially into the fuel release depression having a ring-like or ring segment-like design.
Provisions may be made in an embodiment of the atomizing nozzle according to the present invention that is especially preferred for fluidic reasons for the flow guide element to be essentially concentric to a central axis and for the fuel release depression to be designed as an annular groove-like depression arranged essentially concentrically to the central axis.
To make it possible to atomize the fuel fed in via the atomizing nozzle according to the present invention utilizing shear flows, it is proposed that the flow guide element separate an outer swirling flow from an inner swirling flow and that the flow guide surface be a surface of the flow guide element guiding the inner swirling flow. Provisions may be made, e.g., for the flow guide element to be surrounded in an axial end area of the flow guide element that provides the atomizing lip by an outer flow guide element guiding the outer swirling flow together with the flow guide element. Furthermore, provisions are made concerning the guiding of the inner swirling flow for the flow guide element to surround at least in some areas an inner flow guide element guiding the inner swirling flow together with it and for the fuel release depression to be provided at least partially in an area of the flow guide element surrounding the inner flow guide element.
Provisions may be made in another, especially advantageous embodiment of the atomizing nozzle according to the present invention for feeding the total amount of combustion air used to burn the fuel atomized by means of the atomizing nozzle by the outer swirling flow and the inner swirling flow. It can be achieved in this manner that the combustion taking place in a burner having an atomizing nozzle according to the present invention takes place with excess air, i.e., in a lean range in the entire combustion chamber. Besides the fact that a very large amount of air can thus be used for the atomization, a reduction in the NOx emission is achieved due to the total amount of combustion air being sent through the atomizing nozzle. It shall be pointed out here that if a plurality of atomizing nozzles are to be provided in a burner according to the present invention, the outer and inner swirling flows of all atomizing nozzles are obviously to be understood in this sense, in general, to be the outer swirling flow and the inner swirling flow, which in turn means that the total amount of air used for the combustion is introduced into a burner distributed over the different atomizing nozzles.
Another advantageous aspect of the atomizing nozzle according to the present invention is that an igniting member is provided in same for igniting a combustion air-fuel mixture in a volume area defined at least partially by the flow guide element.
According to another aspect of the present invention, the object mentioned in the introduction is accomplished by means of an atomizing nozzle for a burner, especially for a vehicle heater, comprising a flow guide element, which provides a flow guide surface and which has an atomizing lip in an end area, wherein the flow guide element separates an outer swirling flow from an inner swirling flow, as well as a fuel feed device for feeding fuel to the flow guide surface at a spaced location from the atomizing lip.
Provisions are now made according to the present invention for the total amount of combustion air used for the combustion of the fuel atomized by means of the atomizing nozzle to be fed in by the outer swirling flow and the inner swirling flow.
As was explained above, this device leads, on the one hand, to the advantage of improved atomization, because a larger amount of air can be used than in the case in which only part of the air necessary for the combustion flows through an atomizing nozzle or a plurality of atomizing nozzles. Furthermore, improved combustion and consequently a reduced pollutant emission are also achieved by the improved mixing of the atomized fuel with the air fed in.
According to another aspect of the present invention, the present invention provides for an atomizing nozzle for a burner, especially for a vehicle heater, comprising a flow guide element, which provides a flow guide surface and which has an atomizing lip in an end area, as well as a fuel feed device for feeding fuel to the flow guide surface at a spaced location from the atomizing lip.
Furthermore, an igniting member for igniting a combustion air-fuel mixture in a volume area defined at least partially by the flow guide element is provided in this atomizing nozzle.
This embodiment of an atomizing nozzle according to the present invention leads to the advantage of accelerated ignition process, with the consequence that the pollutant emission can be reduced especially during the ignition process. Provisions may me made here, e.g., for the flow guide element to separate an outer swirling flow from an inner swirling flow and for the igniting member for igniting the combustion air-fuel mixture to act in a central backflow area formed in the inner swirling flow.
Furthermore, the present invention pertains to a vehicle heater, which has a burner with an atomizing nozzle according to the present invention, or to a device for the heat treatment of an exhaust gas aftertreatment system, especially for the thermal regeneration of a particle filter and/or for heating a catalytic converter, which said device has a burner equipped with an atomizing nozzle according to the present invention, which said burner preferably is or can be positioned in the exhaust gas stream. Furthermore, the present invention pertains to a device for generating process gases from liquid fuels, e.g., gasoline, diesel fuel, heating oil, methyl alcohol, ethyl alcohol, which said device has a burner equipped with an atomizing nozzle according to the present invention.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
In the drawings:
Referring to the drawings in particular,
The atomizing nozzle 10 according to the present invention comprises a nozzle body 12, which is or can be fixed, e.g., on a wall of the burner. Essentially three inserts 14, 16, 18, which will be described hereinafter in detail, are arranged in the nozzle body 12. The inserts 14, 16, 18 are arranged in an opening 20 of the nozzle body 12 such that an intermediate space 24 for feeding combustion air by means of a blower is formed in the radially outer area of the inserts 14, 16, 18 to a wall 22 of the nozzle body 12, which said wall surrounds the inserts.
The insert 14, which is also shown in its entirety in
In an approximately cylindrical end area 34 located at a spaced location from the inner flow guide element 14, the central flow guide element 16 has an atomizing lip 36, which is ring-like because of the symmetry of the central flow guide element 16 to the longitudinal central axis A. This means that the flow guide surface 28 of the central flow guide element 16, by which the inner swirling flow is defined in the radially outward direction, also ends at this atomizing lip 36.
On its other axial or radial side, i.e., on the side located opposite the flow guide surface 28, the central flow guide element 16 forms an additional flow guide surface 38 for an outer swirling flow. A flow space area 40 for the outer swirling flow is defined between the flow guide surface 38 of the central flow guide element 16 and a flow guide surface 42 of the insert 18, which is to be considered to be an outer flow guide element, the flow guide surface 42 being located opposite the flow guide surface 38. In the area of its flow guide surface 42, the outer flow guide element 18, which is shown in greater detail in
Consequently, the flowing air, which is fed in through the space area 24 from the radially outward direction under the action of the above-mentioned blower and is then split into the two flow space areas 26, 40, flows in the form of the inner swirling flow Si and the outer swirling flow Sa from the radially outward direction in the radially inward direction and thus enters the area of the atomizing lip 36 from both sides, i.e., from the outside and from the inside. Predetermined by the geometry of the flow deflecting elements 32, 44, these two swirling flows Si and Sa may have the same direction of rotation or an opposite direction of rotation in relation to one another. These two swirling flows Si and Sa will then meet each other in the area of the atomizing lip 36 and lead to the atomization of the combustion air, which is likewise fed to the atomizing lip 36, as is described especially in reference to
It can be recognized from
Consequently, as was mentioned above, the fuel is supplied via at least one fuel feed channel section 54 of the fuel feed channel device 52 into the area of the bottom area 56. The fuel optionally enters the channel areas 66 under an admission pressure. In case of corresponding dimensioning, which may also be coordinated with the viscosity of the fuel being used, the fuel present in the channel areas 66 may be delivered forward in the channel areas by capillary effect, so that it will also reach, e.g., the areas in which the openings 64 establish a connection with the side of the depression 50 that is open radially inwardly. At the openings 66 located distributed over the circumference, the fuel being delivered to these areas by capillary effect and optionally also by the effect of the admission pressure will then escape from the depression 50 and form, as can be recognized in
Based on the delivery effect mentioned above, the fuel is distributed very uniformly in the circumferential direction around the longitudinal central axis A in the depression 50 even if only a single fuel feed channel section 54 is provided, so that a likewise uniform wetting of the flow guide surface 28 takes place in the area thereof The consequence of this is that highly uniform fuel atomization is also achieved over the circumference of the atomizing lip 36, distributed under the effect of the two swirling flows Si and Sa and the shearing action present in the area of the atomizing lip 36. The uniform atomization of the fuel leads to a likewise uniformly distributed combustion of the fuel particle-combustion air mixture thus generated. This in turn results in a combustion with very low pollutant emission, which can also be supported, especially according to another aspect of the present invention, by feeding in the total amount of fuel needed and used for the combustion of the fuel fed in, in the form of the two swirling flows Si and Sa. Thus, a highly efficient shearing action can be obtained and very good premixing of the fuel particles generated by the atomization with the combustion air fed in can be achieved already in the area close to the atomizing nozzle. It shall be pointed out here that the total amount of air used for the combustion is, of course, split among the different atomizing nozzles in the case of a burner that has a plurality of atomizing nozzles 10 according to the present invention, and the individual amounts of combustion air fed to the atomizing nozzles in this case are introduced into the combustion chamber completely in the form of the two swirling flows Si and Sa via the atomizing nozzle 10.
Another advantage of the fuel feed according to the present invention via the groove-like depression 50 is the fact that the need to deliver the fuel fed in by one of the swirling flows to a flow guide surface is eliminated. Furthermore, the depression with the fuel distribution element 58 present therein forms a fuel reservoir, so that equalization of the release of fuel in the direction of the atomizing lip 36 can be achieved even in the case of variations in pressure or changes in the amount of fuel being fed.
It shall be pointed out here that any material suitable for this purpose, e.g., metal, fuel and heat resistant plastic, or ceramic, may be used for both the fuel distribution element 58 according to FIG. 11 and the fuel distribution element shown in
Another embodiment of a fuel distribution element, not shown, may comprise, e.g., a tubular element, which has a plurality of optionally comparatively small openings distributed in its tube wall, via which fuel that had been fed in in the area of the bottom area 56 of the depression 50 and has optionally already been predistributed can enter, on the one hand, and, on the other hand, the fuel can then again escape in the direction of the flow guide surface 28 in the section facing away from the bottom area 56.
It shall be pointed out that the depression 50 discussed above as well as the various fuel distribution elements 58 that may be provided therein do not, of course, have to be necessarily arranged in the circumferential direction around the longitudinal central axis A, even though this is highly advantageous for manufacturing technical reasons and because of the most uniform fuel release possible. The various fuel distribution elements 58 may also be composed of a plurality of segments arranged following each other in the circumferential direction in the case of a depression 50 extending, e.g., circularly in the circumferential direction as well.
Another aspect of the present invention can be recognized in FIG. 8. An igniting member 80, designed, e.g., as a glow-type ignition pin, can be recognized there in an area centered in relation to the longitudinal central axis A. This igniting member 80 is positioned such that with its end area 82 providing the temperatures necessary for the ignition, it protrudes into a volume area 84, which is defined in the radially outward direction by the central flow guide element 16 and in which a recirculation R generated because of the flow dynamics is also present. The combustion air led by the recirculation into this area, which is also arranged centrally in relation to the inner swirling flow Si, already contains very fine fuel particles generated before in the area of the atomizing lip 36, so that an ignitable fuel particle-combustion air mixture enters the area of the igniting member 80 due to this recirculation R. To protect the glow-type igniting member 80 from excessive cooling because of the inner swirling flow Si flowing in at a comparatively high velocity, it is possible, e.g., to insert this igniting member 80 in the central area of the insert that can be recognized in
In case of use in a burner of a heater, e.g., of a vehicle parking heater, the atomizing nozzle according to the present invention leads to very uniform combustion. This is due essentially to the fact that the fuel is fed highly uniformly in the direction of the atomizing lip, and that a very large amount of air, namely, essentially the total amount of air used for the combustion of the atomized fuel, is also utilized to generate the fine fuel particles. The atomizing nozzle according to the present invention may also be used in other areas, e.g., in a regenerating burner for a particle filter in exhaust gas systems of an internal combustion engine, as is disclosed, e.g., in DE 195 04 183 A1. The disclosure contents of this public disclosure document are also included by reference to the disclosure contents of this text especially in light of the design embodiment of such a regenerating burner. Another area of use of an atomizing nozzle according to the present invention or of a burner containing such an atomizing nozzle in an exhaust gas aftertreatment system is the preheating of a catalytic converter intended for exhaust gas cleaning. The burner operating now as a so-called catalytic converter burner, which may also be positioned in the exhaust gas stream, is used to bring the catalytic converter to a suitable operating temperature as rapidly as possible at the start of a vehicle engine in order to reduce the pollutant emission during the cold start phase. Another area in which the atomizing nozzle according to the present invention or a burner containing same may be used is the generation of process gases, e.g., for fuel cells, from liquid fuels, e.g., gasoline, diesel fuel, heating oil, methyl alcohol, ethyl alcohol, etc. A process gas is provided here by means of a cold flame, i.e., a flame with a comparatively low temperature, e.g., as an energy source for the drive of the vehicle, for generating electricity for onboard power supply systems of vehicles, or for generating heat in a vehicle preheater. Process gas generated in this manner may also be used in the household for both generating electricity and for home heating.
It shall be pointed out that especially the group of features relating to the fuel supply via an annular groove may also be used in an atomizing nozzle in which only one of the swirling flows, i.e., for instance, the inner swirling flow, is present, which will then flow along the associated flow guide surface and the depression provided therein and entrains the fuel fed in via the depression in the direction of the atomizing lip.
The total amount of air necessary or used for the combustion may be fed in within the framework of this single flow, which could, of course, also be the outer swirling flow. Furthermore, it is pointed out that it would also be possible to feed the fuel in the area of the flow guide surface 38 located outwardly and leading to the atomizing lip 38.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
Number | Date | Country | Kind |
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102 05 573 | Feb 2002 | DE | national |
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0 660 038 | Jun 1995 | EP |
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Number | Date | Country | |
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20030150932 A1 | Aug 2003 | US |