EP1552218B1 - Burner, particularly venturi burner, comprising a combustion chamber tube - Google Patents

Abstract

A method for fitting a burner into a fuel fired mobile heater has the venturi jet burn valve (14) fitted into the end wall (20) of the burn chamber (16) via a thermal insulating seal (36). The end wall is fitted to one end of the inner wall (18) of the burn chamber which is attached to the outer housing (40) at the opposite end of the burn chamber, where the exhaust duct (50) is attached. The venturi valve has a primary air inlet (24) and a fuel inlet (28) and the flame is directed onto a baffle plate (46) inside the burn chamber. Secondary air holes (32) are provided in the end wall around the valve and the baffle is cooled by additional air inlets (44) in the burn chamber wall near the baffle. A ring shaped gap (42) between the burn chamber and the outer housing insulates the burn chamber. The outer housing is secured to the heater frame at the burner end. Additional outer baffles (58) shield the burner control system from excessive heating.

Description

Background of the invention

The invention relates to a burner, in particular a Venturibrenner for a mobile heater, with a burner nozzle on an end face of a combustion chamber, a combustion chamber tube which surrounds the combustion chamber, and a combustion chamber end wall which limits the combustion chamber to the burner nozzle. Furthermore, the invention relates to a mobile heater with such a burner.

In mobile heaters, especially for use as a heater for vehicles or aircraft, burners are used, which convert the stored energy in liquid or gaseous fuels into heat energy. The burners basically consist of a burner nozzle for spraying and conditioning the liquid fuel, and a combustion chamber, in which the thus treated fuel is sprayed. The burner nozzle and the combustion chamber are further supplied with air for the combustion of the fuel. From the combustion chamber, the burnt fuel exits as exhaust gas into a flame tube and subsequently through a heat exchanger into an exhaust gas line.

In principle, it is desirable that a high level of heat energy is generated during combustion in the combustion chamber. At the same time, however, components of the heater, which are not exposed to high heat load, are arranged on the side of the burner nozzle facing away from the combustion chamber allowed to. Such components may be, for example, electronic components of a controller of the heater.

In such heaters also the area of the combustion chamber must be hermetically sealed from the environment and a possible escape of fuel gas to the side facing away from the combustion chamber side of the burner nozzle must be reliably prevented.

To achieve such a hermetic seal the combustion chamber is off DE 100 19 890 A1 a burner with a Venturi nozzle, in which a combustor tube surrounding the combustion chamber is formed at its end facing the burner nozzle double-walled with two tube walls. The two tube walls are close to each other and are each provided with a collar at the end. The collar of the inner tube wall is directed towards the burner nozzle, while the collar of the outer tube wall is turned away from the burner nozzle, towards an outer housing. At the collar of the inner tube wall, the burner nozzle is fixed and with the collar of the outer tube wall, the combustion chamber tube itself is attached to the outer housing. In this way, a combustion chamber end wall is formed with the two coils, which is fixed radially on the outside of the outer housing and is fixed to the radially inside of the burner nozzle.

A burner with a Venturi nozzle must have a secure seal between the burner nozzle and the combustion chamber end wall. This is in the burner according to DE 100 19 890 A1 a seal is inserted between the burner nozzle and the combustion chamber end wall. This seal is designed so large that it also serves radially outside as a seal between the combustion chamber end wall (ie the collar of the outer pipe wall) and the outer housing. In this way, with the help of a single seal a hermetic seal can be created at two areas simultaneously. With the seal is sealed between the inner and outer pipe wall and so an undefined air supply prevented in the combustion chamber.

The arrangement according to DE 100 19 890 A1 However, has the disadvantage that it may come to leaks due to dimensional variations of the individual components (in particular of the outer casing and the tube walls of the combustion chamber tube). In addition, in this arrangement, such components, which are located on the side facing away from the combustion chamber side of the burner nozzle, can be shielded only with great effort compared to the high temperatures in the combustion chamber.

Further describes JP-61038316 a burner wherein the burner nozzle is held solely on the combustion chamber end wall, and wherein the combustion chamber tube is held solely on its end region remote from the combustion chamber end wall on an outer tube.

Underlying task

The invention has for its object to improve a heater of the type mentioned in such a way that it is cheaper to manufacture in the region of its burner and in particular the above-mentioned problems with respect to the sealing of the combustion chamber and with respect to the thermal decoupling of heat-sensitive components of the heater relative to the burner are overcome.

Inventive solution

This object is achieved according to the invention with a burner above, in which in particular the burner nozzle is supported solely on the combustion chamber end wall, the combustion chamber pipe is supported solely on its end remote from the combustion chamber end wall on an outer tube and between the combustion chamber end wall and the outer tube for an air-permeable annular gap is trained. Furthermore, the object is achieved with a heater that is equipped with such a burner.

In a burner designed in accordance with the invention, a shielding wall is further arranged on the outer tube at its end facing the burner nozzle, by means of which components which are arranged on the side of the burner nozzle facing away from the combustion chamber are shielded from heat with respect to the combustion chamber end wall. The shielding wall can be supported in a particularly simple manner in the region of the second seal on the outer housing of the heater. It can have flow guiding devices by means of which the secondary and / or the tertiary air flow can be influenced with regard to the volume of air per unit of time.

The inventive design is the above-mentioned sealing problem avoided. According to the burner nozzle is supported solely on the combustion chamber end wall, so that there in a simple and effective way a seal can be created. In addition, according to the invention, the combustion chamber pipe is fastened to an outer pipe solely at its end remote from the burner nozzle. Also in this area can be created in a simple manner, for example by a weld, a seal.

In addition, due to the inventive design of the burner, the burner nozzle via the combustion chamber end wall and the combustion chamber tube is fixed solely on the side remote from the burner nozzle end of the combustion chamber tube. Furthermore, an annular gap is formed between the combustion chamber end wall and the outer housing. In this way, a thermal decoupling in the region of the combustion chamber end wall is created. The heat energy which is generated in the combustion chamber and transmitted to the burner nozzle, the combustion chamber end wall and the combustion chamber tube is therefore transferred in the heater according to the invention alone at the end facing away from the burner nozzle end of the combustion chamber tube by heat conduction to the outer tube. Thus, components that are located on the side facing away from the combustion chamber side of the burner nozzle are better protected against heat input.

Advantageous developments of the invention

In an advantageous development of the invention, the burner nozzle is provided with at least one first opening through which primary air can be introduced into the combustion chamber. Such a first opening serves to improve the atomization of the liquid fuel in the burner nozzle. The opening is freely accessible due to the inventive arrangement of the burner nozzle for primary air, so that a variety of types of air supply ducts can be formed on the burner nozzle.

Furthermore, it is advantageous that the combustion chamber end wall is provided with at least one second opening through which secondary air can be introduced into the combustion chamber. By such a secondary air supply a stepped combustion air supply is created, with which the quality of the combustion improved and thus the total pollutant emissions of the burner can be reduced. Said first and second openings can be sealed particularly advantageous with respect to a common combustion air supply with the arrangement according to the invention.

In addition, the arrangement according to the invention forms in the region of the combustion chamber the prerequisite that the combustion chamber tube is provided with at least one third opening through which tertiary air can be introduced into the combustion chamber. The quality of the combustion can be further increased in this way.

With the supply of tertiary air, it is also possible that in the combustion chamber, a baffle plate is arranged and the third opening in the combustion chamber tube is formed such that the baffle plate is cooled by means of the tertiary air. Such targeted cooling of the baffle plate reduces its temperature during combustion. Therefore, it is possible that a less temperature-resistant and therefore less expensive material is used for the baffle plate.

The arrangement according to the invention can be sealed in a particularly simple manner with respect to the area of the heater remote from the combustion chamber by arranging a first seal between the burner nozzle and the combustion chamber end wall. This first seal can be designed specifically from a temperature-resistant material. The seal can be preassembled during assembly of the burner nozzle to the combustion chamber end wall, so that subsequently already a tightness control is possible. Furthermore, the like assembled assembly of burner nozzle and combustion chamber is to be tested for its proper function.

In addition, in the burner according to the invention, the outer tube is advantageously supported at its end region facing the burner nozzle on an outer housing, and a second seal is arranged between the outer tube and the outer housing. Such a supported outer tube can be lapped on its outside by, for example, liquid heat transfer medium and thereby cooled. In other words, the outer tube is attached to a cooled by liquid heat transfer outer housing. The second seal can be designed specifically from a material that is considerably less temperature-resistant than the above first seal. Because the first and second seals are arranged separately from one another according to the invention, dimensional tolerances in the axial direction of the combustion chamber do not have any effect on the sealing concept according to the invention. In addition, thermal expansion of the combustion chamber end wall in the radial direction can be better compensated. The second seal needs to be mounted in the heater only at the final assembly of the burner and therefore can not be damaged during the previous pre-assembly of the burner.

Brief description of the drawing

• Fig. 1 einen Längsschnitt eines Brenners in einem mobilen Heizgerät gemäß der Erfindung.

Hereinafter, an embodiment of a burner according to the invention will be explained in more detail with reference to the accompanying schematic drawing. It shows:

• Fig. 1 a longitudinal section of a burner in a mobile heater according to the invention.

Detailed description of the embodiment

In Fig. 1 a mobile heater 10 in the region of a burner 12 is illustrated. The burner 12 is designed as a Venturibrenner and has as essential components a burner nozzle 14 and a cylindrical combustion chamber 16 which comprises radially outward from a combustion chamber tube 18 and at the burner nozzle 14 facing end face of a combustion chamber end wall 20 is limited.

The burner nozzle 14 is formed with a substantially cylindrical nozzle body 22 in which a plurality of radial channels 24 are formed for supplying primary air into a first opening 26 of the nozzle body 22 at its end remote from the combustion chamber 16 end. The first opening 26 is formed in the central region of the nozzle body 22 and widened in a funnel shape in the direction of the combustion chamber 16. A fuel supply line 28 serves to supply liquid fuel into the first opening 26 of the nozzle body.

The nozzle body 22 of the burner nozzle 26 is supported solely on the combustion chamber end wall 20, wherein in the combustion chamber end wall 20, a central opening 30 is formed through which the atomized in the first opening 26 fuel can enter the combustion chamber 16. In the nozzle block 22 20 further radial channels 32 are formed on the abutment surface to the combustion chamber end wall, 30 guided by the secondary air to second openings 34 in the combustion chamber end wall 20 becomes. The secondary air enters through these second openings 34 in the combustion chamber 16 and leads there to a stepped combustion with high quality of combustion.

Between the nozzle body 22 and the combustion chamber end wall, a first seal 36 is arranged made of a heat-resistant material, by means of which the nozzle body 22 is sealed relative to the combustion chamber 16 and at the same time attached to the combustion chamber end wall.

The combustion chamber end wall 20 is formed as an angled portion or as a collar of a tube which forms the combustion chamber tube 18 in its otherwise cylindrical portion. The combustion chamber tube 18 is welded at its end region 38 facing away from the combustion nozzle 14 with an outer tube 40. The weld surrounds the combustion chamber tube 18 in an annular manner, wherein a substantially annular contact surface is formed between the combustion chamber tube 18 and the outer tube 40, via which only small quantities of thermal energy are transferred from the combustion chamber tube 18 to the outer tube 40.

In this way, an annular gap 42 is formed between the combustion chamber end wall 20 and the outer tube 40, but also between the combustion chamber tube 18 and the outer tube 40, which leads in particular to the thermal decoupling of the combustion chamber end wall 20 against those components which are facing away from the combustion chamber 16 Side of the burner nozzle 14 are located. Such components may be, for example, electronic components, which in the Fig. 1 not further illustrated. With the designed thermal decoupling, it should be noted in particular that thermal energy of the nozzle body 22 can be transferred to the outer tube 40 by heat conduction only over the relatively long distance to the end region 38 of the combustion chamber tube 18 facing away from the burner nozzle 14.

Tertiary air can also be passed through the annular gap 42 to third openings 44 are formed approximately axially in the center of the combustion chamber tube 18 distributed over the circumference. In the combustion chamber tube 18, a baffle plate 46 is also supported, which is cooled by means of the supplied through the third openings 44 combustion air.

In addition, the annular gap 42 leads to a modified sealing concept, which will be explained in more detail below.

The outer tube 40 is formed at its end remote from the burner nozzle 14 end portion with a first collar 48 to which a flame tube 50 is attached. At its end region facing the burner nozzle 14, the outer tube 40 is provided with a second collar 52 which projects radially outward. This second collar 52 is clamped between a first and a second section 54 and 56, respectively, of a housing, not further illustrated, of the heater 10.

In the region of the clamping of the second collar 52, a shielding wall 58 between the sections 54 and 56 is further clamped, which projects radially inwardly in front of the combustion chamber end wall 20 on the side remote from the combustion chamber 16 of the combustion chamber end wall 20. The thus secured in a particularly simple manner shielding wall 58 serves to shield the above-mentioned components against the heat generated in the combustion chamber 16. The outer tube 40 is surrounded radially on the outside by a heat carrier chamber 60, in which a liquid heat carrier flows. At the second collar 52 of the outer tube 40, a second seal 60 is arranged, by means of which the outer tube 40 is sealed in the region of the clamping with the sections 54 and 56 of the housing relative to the heat transfer chamber 62. The second seal 60 is particularly tuned to the requirements of sealing the heat carrier space 62 from the space around the burner nozzle 14. The flowing in the heat transfer chamber 62 liquid heat transfer medium may not escape into the area around the burner nozzle 14. The second seal 60 is made of a material that is good for liquid handling Room seals and at the same time only relatively low temperatures must withstand.

As a result of the design described above, the first and second seals 36 and 60 can optimally seal off burner 12 independently of dimensional tolerances and their material and shape can be optimally adapted to the particular sealing tasks that are present. In particular, the materials of the two seals 36 and 60 can each be optimally adapted to the prevailing temperature conditions in the sealing regions.

LIST OF REFERENCE NUMBERS

10

heater

12

Burner in the shape of a venturi burner

14

burner

16

combustion chamber

18

combustor

20

Combustion chamber front wall

22

nozzle body

24

radial channel

26

first opening

28

fuel supply line

30

central opening in the combustion chamber end wall

32

radial channel

34

second opening

36

first seal

38

end region facing away from the fuel nozzle

40

outer tube

42

annular gap

44

third opening

46

baffle plate

48

first collar of the outer tube

50

flame tube

52

second collar of the outer tube

54

first section of a housing

56

second section of a housing

58

shielding

60

second seal

62

Heat carrier space

Claims (8)

1. Burner (12), particularly a venturi burner for a mobile heating appliance (10), comprising a burner nozzle (14) at an end face of a combustion chamber (16), a combustion chamber tube (18) which encloses the combustion chamber (16), and a combustion chamber end wall (20) which defines the combustion chamber (16) towards the burner nozzle (14), the burner nozzle (14) being retained solely on the combustion chamber end wall (20), the combustion chamber tube (18) being retained on an outer tube (40) solely at its end region (38) remote from the combustion chamber end wall (20), and an annular gap (42) permeable to air being formed between the combustion chamber end wall (20) and the outer tube (40),
   characterized in that a screening wall (58) is arranged in the immediate vicinity of the burner nozzle (14) on the outer tube (40) at its end facing the burner nozzle (14), by means of which screening wall (58) components which are arranged on that side of the burner nozzle (14) facing away from the combustion chamber (16) are screened against heat relative to the combustion chamber end wall (20).
2. Burner according to Claim 1, characterized in that the burner nozzle (14) is provided with at least one first opening (26) through which primary air can be directed into the combustion chamber (16).
3. Burner according to Claim 1 or 2, characterized in that the combustion chamber end wall (20) is provided with at least one second opening (34) through which secondary air can be directed into the combustion chamber (16).
4. Burner according to one of Claims 1 to 3, characterized in that the combustion chamber tube (18) is provided with at least one third opening (44) through which tertiary air can be directed into the combustion chamber (16).
5. Burner according to Claim 4, characterized in that a baffle plate (46) is arranged in the combustion chamber (16), and the third opening (44) is formed in the combustion chamber tube (18) in such a way that the baffle plate (46) can be cooled by means of the tertiary air.
6. Burner according to one of Claims 1 to 5, characterized in that a first seal (36) is arranged between the burner nozzle (14) and the combustion chamber end wall (20).
7. Burner according to one of Claims 1 to 6, characterized in that the outer tube (40) is retained on an outer casing (54, 56) at its end region facing the burner nozzle (14), and a second seal (60) is arranged between the outer tube (40) and the outer casing (54, 56).
8. Mobile heating appliance (10) having a burner (12) according to one of Claims 1 to 7.

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