POROUS FUEL TREATMENT ELEMENT

The present invention relates to a porous fuel treatment element for an evaporation burner, having at least one tier that is formed from fibers.

Apart from atomizing burners which are likewise used to some extent, evaporation burners in which the liquid fuel is evaporated, subsequently treated with supplied combustion air so as to form a fuel/air mixture, and subsequently reacted in an exothermal reaction, are often used in the case of mobile heating apparatuses that are operated using liquid fuel, such as are used in particular as stationary heaters or auxiliary heaters in vehicles. In particular in the case of a use in vehicles, the fuel that is also utilized for operating an internal combustion engine of the vehicle, in particular for example diesel, petroleum, ethanol, and similar, is often used as the liquid fuel.

The liquid fuel in evaporation burners of this type is usually first supplied to a porous fuel treatment element which serves for storing, distributing, and evaporating the fuel. In particular, a plurality of porous fuel treatment elements which, for example, are in each case adapted to these various functions, can also be provided.

WO 2012/155897 A1 describes an evaporator assembly for an evaporation burner for a mobile heating apparatus, in which an evaporation element has at least one layer from a woven metal fabric from interwoven metal wires. It is furthermore described that a multi-tiered construction in which a layer from a woven metal fabric is combined with a further layer from a non-woven metal fabric is provided, for example.

It is an object of the present invention to provide an improved porous fuel treatment element, an improved evaporation burner, and an improved heating apparatus.

The object is achieved by a porous fuel treatment element as claimed in claim 1. Advantageous refinements are set forth in the dependent claims.

The porous fuel treatment element for an evaporation burner has at least one tier that is formed from fibers. The fibers comprise basalt fibers. The fibers of the at least one tier herein can in particular be formed from basalt fibers, for example. However, it is also possible, for example, for further fibers apart from basalt fibers to be present. The entire fuel treatment element herein can be formed from basalt fibers, for example, or at least be formed from one or a plurality of tiers which comprise basalt fibers. However, it is also possible, for example, for the porous fuel treatment element to additionally have also one or a plurality of tiers which do not include any basalt fibers.

As compared to the fibrous materials that are conventionally used for porous fuel treatment elements, basalt fibers have significant advantages in this application. In comparison to glass fibers or asbestos fibers, for example, basalt fibers have superior physical, mechanical, and chemical properties in terms of a use in a porous fuel treatment element. Basalt fibers are a very strong but nevertheless flexural fibrous material which can in particular be processed in a simple manner so as to form textile planar structures such as, in particular, a felt, a non-woven fabric, a needled mat, a scrim, a woven fabric, a warp/weft-knitted fabric, a knitted fabric, or a braided fabric. The material herein is in particular also suitable for evaporation burners which are conceived for very high operating temperatures, since basalt fibers have an extremely high resistance to temperature, in particular also when compared with conventional materials such as, in particular, non-woven metal fabrics and woven metal fabrics. A very slight tendency towards forming deposits is furthermore achieved, and a high storing or buffering effect, respectively, for as yet non-evaporated liquid fuel can be provided. This is furthermore a very cost-effective material that is non-hazardous in terms of health.

According to one refinement, the at least one tier has a textile planar structure, in particular a felt, a non-woven fabric, a needled mat, a scrim, a woven fabric, a warp/weft-knitted fabric, a knitted fabric, or a braided fabric. In this case, the properties of the fuel treatment element can be predefined in a very targeted manner by way of the selection of the textile planar structure. Furthermore, it is also possible, for example, for different types of textile planar structures to be combined with one another, for example one or a plurality of tiers from non-woven fabric with one or a plurality of tiers from woven fabric, etc.

According to one refinement, the fibers of the textile planar structure have a diameter distribution in the range between 5 μm and 35 μm. In this case, a very positively defined distribution of the diameter of the fibers is provided such that the properties of the fuel treatment element can be set in a targeted manner. Furthermore, in the case of such a positively defined diameter distribution it is reliably ensured that no risks in terms of health are associated with the handling of the fibers.

Health hazards in the handling can be excluded in a particularly reliable manner in particular when the fibers have a length of at least 150 μm, preferably a length of at least 200 μm. The basalt fibers in the case of the porous fuel treatment element can particularly preferably be present as so-called endless fibers of a very great length, which can be produced in a known technical manner.

According to one refinement, the porous fuel treatment element can have at least one tier from basalt wool. The aforementioned at least one tier can in particular comprise basalt wool, or else one or a plurality of further tiers which comprise basalt wool or are formed from basalt wool, for example, can be additionally provided. The use of basalt wool enables a particularly cost-effective production.

According to one refinement, the porous fuel treatment element has at least one further tier formed from fibers. The fibers of the at least one further tier can preferably also comprise basalt fibers. A particularly advantageous, in particular temperature-resistant, design embodiment is provided in this case. Alternatively however, it is also possible, for example, for the at least one further tier to comprise other fibers such as, for example, in particular metal fibers or metal wires, respectively.

According to one refinement, the fibers of the at least one tier have a glass-type amorphous structure.

According to one refinement, the fibers of the at least one tier are interconnected by sintering. A particularly robust and dimensionally stable implementation of the fuel treatment element is enabled in this case, which in turn permits simple handling in the assembly of the evaporation burner. Furthermore, an additional separate supporting structure which would cause additional costs and labour input can be dispensed with in this case.

According to one refinement, the fibers are formed by fiber bundles, multifilaments, and/or rovings.

The object is also achieved by an evaporation burner for a mobile heating apparatus operated by liquid fuel, having such a porous fuel treatment element.

The object is furthermore also achieved by a heating apparatus having an evaporation burner which has such a porous fuel treatment element.

Further advantages and refinements are derived from the description hereunder of an exemplary embodiment with reference to the appended drawings in which:

FIG. 1 shows a schematic illustration of part of an evaporation burner having a porous fuel treatment element in a mobile fuel-operated heating apparatus according to one embodiment;

FIG. 2a) shows a schematic illustration of an evaporator receptacle having a fuel treatment element according to a first modification of the embodiment;

FIG. 2b) shows a schematic illustration of an evaporator receptacle having a fuel treatment element according to a second modification of the embodiment;

FIG. 3a) shows a schematic illustration of an evaporator receptacle having a fuel treatment element according to a third modification of the embodiment;

FIG. 3b) shows a schematic illustration of an evaporator receptacle having a fuel treatment element according to a fourth modification of the embodiment;

FIG. 3c) shows a schematic illustration of an evaporator receptacle having a fuel treatment element according to a fifth modification of the embodiment;

FIG. 4 shows a view of a fuel treatment element according to a first embodiment;

FIG. 5 shows a view of a fuel treatment element according to a second embodiment;

FIGS. 6a)-g) show schematic illustrations of various textile planar structures as which the fuel treatment element can be implemented;

FIG. 7 shows a schematic exploded illustration for explaining the arrangement of the fuel treatment element in an evaporator receptacle;

FIG. 8 shows a schematic exploded illustration for explaining the arrangement of the fuel treatment element in an evaporator receptacle in the case of a modification.

EMBODIMENTS

A first embodiment will be described in more detail hereunder with reference to FIG. 1.

A region of an evaporator receptacle 2 and of a burner lid 3 of an evaporation burner 1 for a mobile heating apparatus is schematically illustrated in FIG. 1. FIG. 1 is a schematic illustration in a plane that includes a main axis Z of the evaporation burner. The evaporation burner can be substantially rotationally symmetrical in relation to the main axis Z, for example. The evaporation burner 1 can be configured for a vehicle heating apparatus, for example, in particular an auxiliary heater or a stationary vehicle heater. The evaporation burner 1 herein is configured in particular for converting a mixture of evaporated fuel and combustion air, thus a fuel/air mixture, in a combustion chamber 4, while releasing heat. The conversion herein can be performed in particular in a flame-generating combustion, but a partially or fully catalytic conversion is also possible. The released heat in a heat exchanger (not illustrated) is transmitted to a medium to be heated, which can be formed by air or a coolant liquid, for example. Not illustrated in the schematic illustration of FIG. 1 are in particular the heat exchanger, the discharge for the hot combustion exhaust gases, the combustion-air conveying device (for example a blower) that is likewise provided, the fuel conveying device (for example a metering pump), the control unit for actuating the evaporation burner, etc. These components are well-known and are described in detail in the prior art.

The evaporation burner 1 has an evaporator receptacle 2 in which a porous fuel treatment element 5 is disposed. The evaporator receptacle 2 in the case of the exemplary embodiment is substantially pot-shaped. The fuel treatment element 5 is received in the pot-type depression of the evaporator receptacle 2 and in particular can be fixedly held in the latter, for example by welding, brazing/soldering, jamming, or with the aid of a suitable securing element. The design embodiment of the fuel treatment element 5 will be described in even more detail hereunder.

A fuel supply line 6 for supplying liquid fuel to the fuel treatment element 5 is provided. The fuel supply line 6 opens into the evaporator receptacle 2 and is connected to a fuel conveying device (not illustrated) by way of which liquid fuel in a predefined quantity can be conveyed through the fuel supply line 6, as is schematically illustrated by an arrow F. The fuel supply line 6 is fixedly connected to the evaporator receptacle 2, for example by welding or brazing/soldering.

The combustion space 4 on the circumference is delimited by a combustion chamber 7 which can be formed, for example, by a substantially cylindrical component from a temperature-resistant steel. The combustion chamber 7 is provided with a plurality of bores 7a by way of which the combustion air can be supplied to the combustion space 4, as is schematically illustrated by arrows in FIG. 1. The bores 7a herein are part of a combustion air supply L by way of which the combustion air is supplied to a side of the fuel treatment element 5 that faces away from the fuel supply line 6.

The evaporation burner 1 is configured in such a manner that in operation liquid fuel can be supplied by way of the fuel supply line 6 to the fuel treatment element 5. On the one hand, on account of a multiplicity of cavities, a distribution of the fuel across the entire width of the fuel treatment element 5 is performed in and on the fuel treatment element 5, and an evaporation or volatization, respectively, of the fuel is performed on that side that faces the combustion space 4, on the other hand. In the case of the embodiment illustrated, the fuel treatment element 5 has a substantially circular cross-sectional shape, the main axis Z of the evaporation burner 1 running in the center of said circular cross-sectional shape. However, the fuel treatment element 5 can also have other cross-sectional shapes.

The combustion burner 1 is configured in such a manner that an evaporation or volatization, respectively, of the liquid fuel is performed in the fuel treatment element 5 and on the surface of the latter, the evaporated fuel being mixed with the supplied combustion air so as to form a fuel/air mixture only when exiting from the fuel treatment element 5, that is to say at the side of the combustion space. The supply of liquid fuel and combustion air is thus performed on different sides of the fuel treatment element 5. The conversion of the fuel/air mixture in an exothermal reaction herein does not take place in the fuel treatment element 5 but in the downstream combustion space 4. In the operation of the evaporation burner 1 there is thus liquid fuel and fuel vapor in the fuel treatment element 5, and any air that is potentially initially present is forced out of the fuel treatment element 5 by virtue of the evaporation or volatization process, respectively.

In the case of the exemplary embodiment schematically illustrated in FIG. 1, the fuel treatment element 5 has a construction with a plurality of functional regions, said construction in the example specifically illustrated being subdivided into a first region B1 and into a second region B2, the latter having a structure that deviates from the structure in the first region B1.

The second region B2 in the case of the exemplary embodiment is disposed so as to face the fuel supply line 6, and the first region B1 is disposed so as to face the combustion space 4.

In the case of the first modification of the embodiment schematically illustrated in FIG. 2a), the fuel treatment element 5 does not have a plurality of different functional regions, there rather being only one first region B1.

In the case of the second modification of the embodiment schematically illustrated in FIG. 2b), the fuel treatment element 5 has a stepped design with a total of three regions B1, B2, B3, and the evaporator receptacle 2 is configured in a corresponding manner. In such a case, the different regions B1, B2, B3 can be conceived in a targeted manner with a view to the various functions of the fuel treatment element 5, for example. For example, the second region B2 can be optimized for conveying fuel by way of capillary forces and for temporarily storing fuel, the third region B3 can be optimized with a view to a distribution of fuel in the transverse direction and serve for compensating tolerances, and the first region B1 can be optimized with a view to the evaporation or volatization, respectively, of fuel. The different regions B1, B2, B3 herein can differ from one another in particular in terms of the construction, the structure, the material, and/or the thickness, etc. thereof.

Further potential design embodiments of fuel treatment element 5 having a plurality of functional regions B1, B2, B3 are schematically illustrated in FIGS. 3a, 3b, and 3c. While the fuel supply line 6 and further components are again not illustrated in FIGS. 3a, 3b, and 3c, it is understood that these further components are also present in the case of each of these further modifications.

The construction of the fuel treatment element 5 as can be used in the case of the embodiment and the modifications described above will be described in more detail hereunder The design embodiment herein described hereunder can be used for each one of the regions B1, B2, and B3, in particular also in those cases in which only one such region is provided.

FIG. 4 shows a tier 8, formed from fibers 10, of a porous fuel treatment element 5 according to a first embodiment. The tier 8 in the case of this embodiment is formed from a woven fabric, the fibers 10 of the latter comprising basalt fibers. In the case of the specific embodiment illustrated, the woven fabric herein is in particular formed by basalt fibers which are interwoven. In the case of the porous fuel treatment element 5 having one or a plurality of further tiers 9, said further tiers 9 can also be formed from such a woven fabric, for example. The fibers 10 within the tier 8 formed can also be fiber bundles, multi filaments, or rovings, respectively.

FIG. 5 shows a tier 8, formed from fibers 10, of a porous fuel treatment element 5 according to a second embodiment. The tier 8 in the case of the second embodiment is formed as a non-woven fabric which comprises basalt fibers. In the case of the specific embodiment illustrated, the non-woven fabric herein is in particular formed by basalt fibers. In the case of the porous fuel treatment element 5 having one or a plurality of further tiers 9, said further tiers 9 can also be formed from such a non-woven fabric, for example. Furthermore, in a fuel treatment element 5 it is also possible, for example, for one or a plurality of tiers from such a non-woven fabric to be combined with one or a plurality of tiers from a woven fabric as described above.

Furthermore, in a porous fuel treatment element 5, one or a plurality of tiers can also be configured as textile planar structures such as are described in general hereunder with reference to FIGS. 6a) to 6g). It is to be noted herein in particular that arbitrary combinations of such textile planar structures can be used in a porous fuel treatment element.

Various implementations of the at least one tier 8 (or optionally also of the further tier 9, respectively) of the porous fuel treatment element 5 are illustrated in FIGS. 6a) to 6g). The various implementations have a common factor in that the fibers 10 in each case comprise basalt fibers. In particular, the fibers 10 can in each case be formed by basalt fibers.

FIG. 6a) shows a schematic illustration of a non-woven fabric as a textile planar structure for the tier 8 or 9, respectively, as has also been described with reference to FIG. 5.

FIG. 6b) shows a schematic illustration of an alternative in which the textile planar structure for the tier 8 or 9, respectively, is formed by a felt.

FIG. 6c) shows a schematic illustration of a textile planar structure that is formed as woven fabric from basalt fibers for the tier 8 or 9, respectively, as has also been described with reference to FIG. 4.

FIG. 6d) schematically shows a configuration of the tier 8 or 9, respectively, as a knitted fabric. FIG. 6e) schematically shows a configuration of the tier 8 or 9, respectively, as a braided fabric. FIG. 60 schematically shows a configuration of the tier 8 or 9, respectively, as a warp/weft-knitted fabric. FIG. 6g) schematically shows a configuration of the tier 8 or 9, respectively, as a scrim.

It is to be noted that the various textile planar structures that have been described by means of FIGS. 6a) to 6g) in a porous fuel treatment element 5 can be combined with one another in an almost arbitrary manner. In the case of the textile planar structures described above, it is particularly advantageous for the fibers 10, that is to say the basalt fibers in the case of the specific design embodiment, to have a very tight diameter distribution with diameters in the range between 5 μm and 35 μm, and for the fibers 10 to in each case have a length of more than 150 μm, preferably more than 200 μm. The fibers 10 herein can particularly preferably be embodied as so-called endless fibers, for example. The fibers 10 herein have an amorphous glass-type structure. The surface of the fibers 10 can prefereably be treated with a sizing in production, so as to achieve an improved processability.

Alternatively or else additionally to the textile planar structure described above, the tier 8 or 9, respectively, can also comprise basalt wool, which enables a particularly cost-effective production.

The integration of the fuel treatment element 5 described above and the at least one tier 8 or 9, respectively, which comprises basalt fibers, in an evaporator assembly of an evaporation burner 1 will be briefly described hereunder with reference to the schematic exploded illustration in FIG. 7.

As is schematically illustrated in FIG. 7, the fuel treatment element 5 described above is placed into the pot-type depression of the evaporator receptacle 2. In order for a sufficient mechanical stability to be guaranteed even at high temperatures in the long run, a supporting structure 11 which can in particular be formed by a temperature-resistant metal mesh or metal woven fabric, for example, is attached to the fuel treatment element 5 on the side of the combustion space. Fastening of the fuel treatment element 5 and of the supporting structure 11 in the evaporator receptacle 2 is performed by way of a mounting ring 12. The mounting ring 12 herein can be configured in particular in a manner known per se as a circlip which is jammed or braced, respectively, on the evaporator receptacle 2, or a connection between the mounting ring 12 and the evaporator receptacle 2 can be established, for example, by welding or brazing/soldering. The evaporator assembly that is formed in this manner can then be integrated in the evaporation burner 1 in a simple manner.

MODIFICATION

In the case of a modification of the embodiment described above, the mechanical stability of the porous treatment element 5 is enhanced in that the fibers 10 are interconnected by sintering. In this method, a fixed connection is configured therebetween at the intersection points of the fibers 10. Sintering herein can be performed, for example, by way of a purely thermal process in which the configuration of the connection is performed only by providing an increased temperature and optionally by additional compressing of the fibers 10. As an alternative to such a purely thermal process, it is however also possible, for example, for the sintering process to be facilitated by chemical processes in that additional binding agents/sintering additives are applied to the fibers.

As is schematically illustrated in FIG. 8, an enhanced mechanical stability of the fuel treatment element 5 is achieved by way of this modification, such that the additional supporting structure 11 can be dispensed with in the construction of the evaporator assembly.

POROUS FUEL TREATMENT ELEMENT

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