EP1363070A1 - Vaporizing Burner - Google Patents

Abstract

An evaporator burner, in particular for a vehicle heater, comprises a combustion chamber (16) formed in a combustion chamber housing (14), into which fuel is fed via a first porous medium (18), further comprising an ignition chamber (32) open to the combustion chamber (16), into which fuel is fed via a second porous medium (36) and in which an ignition element (46) is essentially completely accommodated. <IMAGE>

Description

The present invention relates to an evaporator burner, in particular for a vehicle heater, which one in a combustion chamber housing Combustion chamber formed, into which a first porous medium Fuel is fed.

Such vaporizer burners are generally designed so that Start the combustion process a protruding into the combustion chamber Ignition device is provided by electrical excitation in its environment generated correspondingly high temperatures. The one in the area near this Ignition device introduced into the combustion chamber via the first porous medium and evaporated fuel there ensures an ignitable mixture, which is initially in the vicinity of the ignition organ due to the prevailing there is ignited at high temperatures. The combustion is spreading then generally ring-like over the entire combustion chamber. Has the combustion can then spread over the entire combustion chamber the ignition device can be deactivated because of the heat of combustion at the same time also sufficient energy to evaporate the over the porous supplied fuel is provided.

A disadvantage of such evaporator burners is that they are comparatively slow Start-up procedure, as essential areas of the combustion chamber are created by the ignition device must be warmed to the necessary for ignition To be able to generate temperatures. This could be compensated Disadvantage due to a correspondingly high glow power, which however Device power consumption increased. Another disadvantage is that before and even after operating the evaporator burner, i.e. before it occurs the ignition and after stopping the combustion by which still prevailing high temperatures a fuel outgassing take place can what is due to the combustion that no longer exists in this state leads to high exhaust emissions and, above all, in Ignition process can result in inhomogeneous combustion.

Another disadvantage with such evaporator burners is that also due to the use of different fuels Deposits, which are on the porous medium, over which actually the fuel is to be fed into the combustion chamber can. Above all, heavy boiling fuels lead to the fact that in certain areas due to lack of heat input and due to insufficient air circulation build up deposits that over the Operating life significantly affect operational efficiency can.

It is the object of the present invention to provide an evaporator burner especially for a vehicle heater to provide a more efficient and with regard to exhaust gas emissions and those occurring in the burner Deposits enables optimized operation.

According to the present invention, this object is achieved by a Vaporizer burner, in particular for a vehicle heater, comprising a combustion chamber formed in a combustion chamber housing, into which Fuel is fed via a first porous medium, further comprising an ignition chamber open to the combustion chamber, in which fuel is fed via a second porous medium and in which a Ignition device is essentially completely absorbed.

It is essential in the evaporator burner according to the invention that Ignition device is no longer used to heat areas of the combustion chamber, the temperatures required to ignite an ignitable mixture to provide, but in a separate, provided for this Ignition chamber is effective, so that first in this ignition chamber Combustion will occur and combustion from the ignition chamber then into the combustion chamber, which communicates with the ignition chamber stands, will spread. As a result, the Concentration of the thermal energy provided for ignition to one reached comparatively small volume range, with the result that the Ignition process runs much faster and thus the period in which excessive exhaust emissions occur during the start-up phase, can be significantly reduced. As a result, the risk of Deposits significantly reduced.

For example, it can be provided that the ignition chamber is in a with the ignition chamber housing connected to the combustion chamber housing is. To further increase the thermal efficiency of the ignition device To be able to, it is proposed that the ignition chamber housing from thermal insulating material is built up and / or with the combustion chamber housing is connected in a thermally insulating manner. For example the ignition chamber housing can be constructed from ceramic material.

To provide an ignitable in the vicinity of the igniter Allow mixture of vaporized fuel and combustion air to it is proposed that the second porous medium is the igniter at least in its thermally effective range while maintaining one Intermediate space is arranged.

According to a further advantageous aspect of the present invention a heating device is assigned to the second porous medium. By this heating device can therefore in addition to that by the ignition element provided thermal energy to ensure that the in the second porous medium introduced fuel also evaporates better. in the The ignition process can therefore be the thermal energy provided by the ignition element essentially to generate the temperatures required for ignition be used in its environment while the heat of vaporization is provided by the heater. For example, can be provided be that the heater has the second porous medium on it is arranged surrounding from the igniter side.

As already stated, it is advantageous if the fuel has a Fuel supply line can be introduced into the second porous medium can. The liquid fuel then becomes the first porous medium preferably supplied with the intermediary of the second porous medium.

To the air required for the ignition process to produce an ignitable Prepare a mixture of combustion air and evaporated fuel To be able to, at least one pilot air inlet opening in the Lead the ignition chamber. For the main combustion, which is in the combustion chamber expires, then the combustion air required can be supplied via a Combustion air introduction arrangement arranged in a central region of the combustion chamber are fed.

In order to get the quickest and most uniform possible ignition ring-like spread of combustion in the combustion chamber generate, it is proposed that a pilot flame deflecting element in the Provided area of the confluence of the ignition chamber in the combustion chamber is.

In another aspect, the present invention relates to a method for removing deposits on an inventive Vaporizer burner, which procedure after finishing a normal Burner operation in the ignition chamber under a fuel deficit spreading the combustion chamber and deposits on the first porous Medium burning combustion is induced.

This procedure ensures that the first under a fuel deficit, i.e. a lean mixture of vaporized Fuel and combustion air running off the combustion in the area the inner surface of the first porous medium, for example soot-like deposits are burned off.

This procedure preferably ensures that simultaneous excitation of the igniter and the heater essentially all of the fuel introduced into the second porous medium the ignition chamber is evaporated. This ensures that the Burn off the deposits accumulated in the combustion chamber further deposits more in the area of the first porous medium itself can accumulate.

The combustion during this cleaning or burning process preferably takes place at a lambda value of at least 2.

Because especially when performing the previous cleaning or Burning process in which the porous medium in the combustion chamber is cleaned due to the essentially complete evaporation of the fuel in the ignition chamber there is a fundamental risk that Deposits are generated in the area of the ignition chamber Another aspect of the invention proposed that after of deposits on the first porous medium Termination of fuel supply and excitation of the ignition device and the Heating deposits in the area of the second porous medium be burned down. By operating the heater at the same time and the ignition device are no longer in the area of the ignition chamber existing fuel feed generates such high temperatures that the deposits present in the area of the second porous medium be burned down.

Fig. 1

eine schematische Längsschnittansicht eines erfindungsgemäßen Verdampferbrenners;

Fig. 2

eine Querschnittansicht des in Fig. 1 dargestellten Verdampferbrenners, geschnitten längs einer Linie II - II in Fig. 1;

Fig. 3

eine Schnittansicht des in Fig. 2 dargestellten Zündkammergehäuses, geschnitten längs einer Linie III - III in Fig. 2.

The present invention is described in detail below with reference to the accompanying drawings. It shows:

Fig. 1

is a schematic longitudinal sectional view of an evaporator burner according to the invention;

Fig. 2

a cross-sectional view of the evaporator burner shown in Figure 1, taken along a line II - II in Fig. 1.

Fig. 3

3 shows a sectional view of the ignition chamber housing shown in FIG. 2, cut along a line III-III in FIG. 2.

1, an evaporator burner according to the invention is generally at 10 designated. The evaporator burner 10 comprises a flame tube 12, which in an axial end region 15, a combustion chamber housing 14 for a inner combustion chamber 16 of the flame tube 12 formed there. The The inner wall of this combustion chamber 16 is provided with a porous medium 18 lined, for example, from felt-like, braid-like or other material with pores, e.g. Foam ceramic or the like, can be formed. Via a blower arrangement shown only schematically 20 and a combustion air inlet port 22 which is in the combustion chamber 16 is arranged centrally and a plurality of air inlet slots 24 has at its peripheral region, combustion air is in the Combustion chamber 16 initiated. The axial closure of the combustion chamber 16 essentially forms a ring-shaped flame diaphragm 26 which through which the combustion gases and the flame merge into the remaining area of the flame tube 12 can extend.

At the end region 15 of the flame tube which forms the combustion chamber housing 12, an ignition chamber housing 28 is attached to the side. This approximately cylindrical ignition chamber housing 28 can with the Combustion chamber housing 14 or the end section 15 of the flame tube 12 with the interim storage of a heat and fuel resistant and preferably O-ring-like formed from thermally insulating material Sealing element 30 may be connected, so that in the transition area between the combustion chamber housing 14 and the ignition chamber housing 28 good thermal insulation is ensured. Furthermore, it should be noted the ignition chamber housing 28 for reasons described below made of thermally insulating material, e.g. Ceramic material.

In the ignition chamber housing 28 there is a ignition chamber, generally designated 32 formed in a mouth region 34 to the combustion chamber 16 is open. This junction area 34 can in the example shown partly also by the one adjoining the ignition chamber housing 28 Material or wall area of the combustion chamber housing 14 is provided his.

On the inner circumference of the ignition chamber housing 28 is the ignition chamber 32 surrounding or lining porous medium 36 provided through an opening 37 formed in the mouth region 34 in the combustion chamber housing 14 and a corresponding opening in the porous medium 18 of the combustion chamber housing 14 extends through. In this area so there is an investment connection between the two porous media 36, 18

Extends in its end region remote from the combustion chamber 16 the porous medium 36 to the area of one on the inside of the Ignition chamber housing 28 formed annular fuel distribution groove 38, into which a fuel supply line 40 opens. In one even further in the direction away from the combustion chamber 16 of the ignition chamber housing 28 are, as can also be seen in FIG. 3, two to each other with respect to a longitudinal center axis of the ignition chamber housing 28 offset and thus approximately tangential or secantial in the Ignition chamber 32 opening ignition air inlet openings 42, 44 formed. It lies centrally in the ignition chamber housing 28 or the one formed therein Ignition chamber 32 is an ignition element 46 designed as a glow ignition pin End region of the ignition chamber housing located away from the combustion chamber housing 14 28 through a connection which also has an electrical connection 48 Carrier 50 is carried on the ignition chamber housing 28. Between the outer peripheral area of which is essentially the whole Ignition chamber 32 extending igniter 46 and the porous Medium 36 an interspace 52 is formed.

2 that the porous medium 36 of the ignition chamber 32 on its outer peripheral area, i.e. on the one facing away from the igniter 46 Side by a heater for this porous medium 36 providing heating coil 54 is surrounded. Both the heating coil 54 as well as the glow plug 46 are electrically excitable, so that at convert electrical energy into heat energy using the appropriate current.

It can also be seen in FIGS. 1 and 2 that in the mouth region 34 a scoop-like pilot flame guide element 56 is provided. This pilot light guide element 56 ensures that one spreading out of the ignition chamber 32 into the combustion chamber 16 Pilot flame does not penetrate the combustion chamber 16 directly and then inside strikes the combustion air inlet port 22, but in the circumferential direction is deflected and thus for a ring-like combustion spread in the combustion chamber 16.

The following is the operation of the previous one in terms of construction Structure described evaporator burner 10 described in detail.

To ignite the evaporator burner 10, the fuel supply line is used first 40 the porous medium 36 of the ignition chamber 32 fuel fed. The heating coil 54 is excited by simultaneous excitation and the glow plug 46 on the one hand for very rapid evaporation of the fuel introduced into the porous medium 36 to others become very much at the same time, especially in the ring-like area 52 quickly provided a sufficiently high temperature to be in the ignition chamber 32 to ignite the ignitable mixture present there. For this is essential that the components to be heated are comparatively similar small thermally well insulated or isolatable room area are limited and not essential components of the combustion chamber 16 need to be warmed up. The consequence of this is that the combustion in the ignition chamber 32 will occur very quickly and this resulting pilot flame flows into the combustion chamber via the mouth region 34 16 will spread, whereby, as already described above, using the flame guide element 56 for a ring-like spread of the Flame is provided in the combustion chamber 16.

Such an amount of fuel is supplied during this ignition process that not all of the fuel in the ignition chamber 32 is above the porous Medium 36 will evaporate, but that over the porous medium 36th fuel also enters the porous medium 18 of the combustion chamber 16 and in this over the outer peripheral region of the combustion chamber 16 will spread. Due to the pilot flame spreading into the combustion chamber 16 is very quickly in the combustion chamber 16 there in the porous medium 18 existing fuel is heated and evaporated, so that due to the already existing during the ignition process Combustion air supply via the nozzle 22 or the openings 24 in the Combustion chamber 16 provides an ignitable mixture that too due to the high temperatures provided by the pilot light will ignite very quickly. It should be mentioned here that through the combustion air supply via the connector 22 in the area of the ignition chamber 32 Vacuum is generated, which the afterflow of ignition air through the Openings 42, 44 will result. Of course it is possible if required, a separate pilot air blower for feeding of ignition air to be provided in the ignition chamber 32.

The inventive design of the evaporator burner 10 can start up very quickly when an ignition process is carried out of the evaporator burner 10 to its nominal output, so that the harmful emissions occurring in this ramp-up phase can be significantly reduced. It is also essential for this that the additional provision of the heating coil 54 also in coordination evaporation optimally the fuel used in each case can be promoted in the ignition chamber 32 without this Providing the ignition temperatures actually provided glow plug 46 excessive heat would have to be removed. Furthermore, through the locally limited heating by the heating coil 54 on the one hand and the Glow plug 46, on the other hand, both in the ignition process and Stopping the heating burner 10 unwanted exhaust gases from fuels can be largely reduced because the defined control of the Heating coil 10 and the glow plug 46 can be ensured that in a locally very limited area the fuel available there is burned completely and very quickly. This is also particularly with With regard to the use of the heating burner according to the invention in connection with different evaporation characteristics Fuels very beneficial.

When operating such a heating burner, there is basically Danger in the area of the combustion chamber and also in the area of the ignition chamber Deposits A and B are generated. To the excessive To avoid accumulation of such deposits, the invention can Heating burner to carry out the following cleaning procedure operate:

First, when transitioning from a normal combustion operation in the out-of-service condition through reduced fuel supply, that a very lean combustion is induced in the ignition chamber and a correspondingly lean ring flame spread into the combustion chamber 16 becomes. Due to the very high proportion of radiant heat present and that due to the above combustion still very hot combustion chamber housing 14 are the Deposits A accumulated in the area of the porous medium 18 burned down this process. Here by appropriate excitement of the Glow plug 46 and the heating coil 54 ensured that the entire provided fuel essentially entirely in the Ignition chamber 32 evaporates, ensuring that this No further deposits get onto the porous medium 18. The amount of fuel supplied is also in proportion to supplied pilot air quantity set so that a combustion at a lambda value of about 2 will expire. Because of this lean Combustion then becomes those present on the porous medium 18 Deposits oxidized and burned. This process is special therefore very effective, since the pilot flame used to burn off spread out in a ring-like manner precisely in that region of the combustion chamber 16 in which deposits A will also be present.

Due to the essentially complete evaporation of the supplied Fuel in the ignition chamber 32 is primarily in this process however, there is a risk that the deposits in the area of the ignition chamber 32 B are generated. These are in a subsequent cleaning process step then burned down that fuel supply is set while still the glow plug 46 and the Heating coil 54 are excited and thus generated such high temperatures be that under the still ongoing supply of pilot air now deposits B are burned off. This process is also very efficient because of the heating coil 54 on the one hand and the glow plug 46 on the other hand, the deposits B are heated from both sides.

The present design of a heating burner means that it is possible to operate it at start-up in such a way that it starts up Nominal power only takes a very short time, which on the one hand electrical energy is saved, on the other hand, those occurring in this phase harmful emissions can be significantly reduced. in the normal combustion operation can ignite the organs effective be completely disabled. Due to the main combustion taking place in the heating burner there is sufficient thermal energy to evaporate and burn of the fuel supplied to the combustion chamber via the porous medium provided. Especially by choosing the shape and positioning of the flame guide element 56 can during the ignition process, as well as at the cleaning process described above, an essential Influence on the spread of the pilot flame in the combustion chamber so that depending on the required flame distribution, the Shape or the positioning of the element 56 can be adjusted.

By means of those to be carried out or carried out further according to the invention Cleaning procedures can take advantage of the beneficial constructive Aspects of the evaporator burner according to the invention ensured be that existing both in the area of the combustion chamber itself Deposits as well as in the area of the ignition chamber may be the first Deposits generated reliably during the cleaning process of the combustion chamber can be burned down. Another advantage of the invention Evaporator burner is its usability in connection with various Fuels, being in any case by accordingly adapted activation of the various heating elements with regard to the fast start-up capacity on the one hand and the lower pollutant emissions on the other hand, existing advantages are retained.

Claims (16)

Vaporizer burner, in particular for a vehicle heater, comprising a combustion chamber formed in a combustion chamber housing (14) (16), in which fuel via a first porous medium (18) is fed, further comprising a to the combustion chamber (16) open ignition chamber (32), in which fuel via a second porous medium (36) is fed and in which an ignition element (46) is essentially completely included. Vaporizer burner according to claim 1,
characterized in that the ignition chamber (32) is formed in an ignition chamber housing (28) connected to the combustion chamber housing (14). Vaporizer burner according to claim 2,
characterized in that the ignition chamber housing (28) is constructed from thermally insulating material and / or is connected to the combustion chamber housing (14) in a thermally insulating manner. Vaporizer burner according to claim 3,
characterized in that the ignition chamber housing (28) is constructed from ceramic material. Vaporizer burner according to one of claims 1 to 4,
characterized in that the second porous medium (36) is arranged to surround the ignition element (46) at least in its thermally effective region while maintaining an intermediate space (52). Vaporizer burner according to one of claims 1 to 5,
characterized by a heating device (54) assigned to the second porous medium (36). Vaporizer burner according to claim 5 and claim 6,
characterized in that the heating device (54) is arranged to surround the second porous medium (36) on its side facing away from the ignition element (46). Vaporizer burner according to one of claims 1 to 7,
characterized by a fuel supply line (40) for introducing liquid fuel into the second porous medium (36). Vaporizer burner according to claim 8,
characterized in that liquid fuel is supplied to the first porous medium (18) via the second porous medium (36). Vaporizer burner according to one of claims 1 to 9,
characterized by at least one ignition air inlet opening (42, 44) leading into the ignition chamber (32). Vaporizer burner according to one of claims 1 to 10,
characterized in that a combustion air introduction arrangement (22, 24) is arranged in a central region (16) of the combustion chamber. Vaporizer burner according to one of claims 1 to 11,
characterized by an ignition flame deflecting element (56) in the region of the opening (34) of the ignition chamber (32) into the combustion chamber (16). Process for removing deposits on an evaporator burner according to one of the preceding claims, in which Procedure after termination of normal burner operation in the Ignition chamber (32) under a fuel deficit in the combustion chamber (16) Spreading and deposits on the first porous Medium (18) burning combustion is induced. A method according to claim 13,
characterized in that essentially all of the fuel introduced into the second porous medium (36) is evaporated in the ignition chamber (32) by simultaneous excitation of the ignition member (46) and the heating device (54). A method according to claim 13 or 14,
characterized in that the combustion takes place at a lambda value of at least 2. Method according to one of claims 13 to 15,
characterized in that after the deposits on the first porous medium (18) have burned off, deposits in the region of the second porous (36) medium are burned off by stopping the fuel supply and excitation of the ignition element (46) and the heating device (54).

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