EP3279569B1 - Mobile radiant heater - Google Patents

Description

The invention relates to a mobile radiant heater, with a combustion unit for burning solid fuel, a solid fuel storage, a transparent radiation unit for radiating combustion heat into the environment, a roof unit arranged on the radiation unit and a flue gas flue which is directed through the radiation unit, the radiation unit being one Glass tube and an opaque flame bundle tube arranged in the glass tube.

For the heating of half-open tents or terraces in the catering and event area, radiant heaters are now known that heat with wood pellets. The wood pellets are burned on a burner plate of the radiant heater, and the flames resulting from the combustion blow upwards into the transparent radiation unit, so that the flames are visible from the outside. The radiation unit is a glass tube that heats up due to the flames blazing inside and radiates heat to the outside. The light generated by the flames and penetrating the glass leads to additional energy radiation. The heating effect is mainly based on the radiant heat of the flames that strikes the person or objects to be heated.

In the known radiant heaters, the amount of heat radiation emitted depends on the extent to which the flames reach from below into the radiation unit. The higher the flames reach, the greater the heating output. A high reaching of the flames from the combustion unit into the radiation unit can be achieved if a strong fire is generated in the combustion unit by a strong combustion air supply, which is caused by the quantity of the supplied Air is torn far up in the radiation unit. However, if the blasting unit comprises a glass tube within which the flames blow upwards, it may happen that the glass tube becomes too hot and softens or even melts in its lower region. This leads to the heater being destroyed.

To solve this problem is out of US 7,175,424 B2 a radiant heater is known which has two radiating glass tubes as a radiation unit. The space between the glass tubes can be flushed with water, so that the glass tubes are cooled and the flames can still radiate their heat through the glasses and water.

From the DE 202011001786 U1 a radiant heater is known which has a flame guide in the interior of the glass tube with a plurality of cones arranged one above the other, which should keep the flames as central as possible and thus as far apart as possible from the glass tube in order to protect it sufficiently from excessive heating.

In the DE 102010007478 A1 describes a radiant heater which has two tubes lying one inside the other as a radiation unit. Ambient air is led into the space between the pipes, which is warmed up and led to the surroundings as warm air for heating.

From the EP 1 326 052 A2 is a stove or fireplace with a fireplace, in which a flame stretching device is arranged near the fireplace. The flame stretching device has a glass tube or a wire mesh and is at least partially surrounded by a sight glass.

It is an object of the present invention to further improve a radiant heater with a combustion unit for burning solid fuel.

This object is achieved by a radiant heater of the type mentioned, in which the radiation unit has a base and a lower base, the flame bundle tube running through an opening in the base and comprising a lower collar with which it stands on the lower base, the Radially from the outside in the vicinity of the flame bundle tube, or the flame bundle tube comprises an upper collar with which it forms a positive connection with the roof unit, so that the flame bundle tube hangs on the roof unit.

The most effective heating effect is achieved with a radiant heater if the flames are drawn from the combustion chamber as high as possible into the radiation unit, i.e. strong and as long as possible over the greatest possible length has, through which flames rising within the flame tube are visible from the radially outside.

The invention is based on the consideration that the most effective heating effect is achieved with a radiant heater if the flames are drawn from the combustion chamber as high as possible into the radiation unit, that is to say that it is heated strongly and as uniformly as possible over a long length. If, in addition, the flames radiating in the visible spectral range reach as high as possible into the radiation unit, a pleasant optical effect of the firelight can be achieved in addition to the energy gain from the radiation. The radiation unit heats up in the lower area to between 600 ° C and 900 ° C, thus reaching the orange-glowing temperature range.

However, if the flames are bundled inside the radiation unit and can only reach an outer glass tube of the radiation unit to a limited extent, this can remain cooler than if the flames reach the glass tube unhindered. The flame bundle tube arranged in the glass tube allows the flames to be bundled inside the radiation unit so that the outer glass tube is protected. The high flame temperature remains essentially restricted to the flame bundle tube, which can glow orange, and the temperature of the glass tube remains relatively cool even in the lower region and the glass is stable.

According to the invention, the flame bundle tube is opaque, for example at least predominantly made of metal and / or ceramic, so good heat radiation can be achieved through the flame bundle tube, since metal radiates more than glass. Opaque can be understood to mean an opacity above 90%, in particular above 99%, in which below 10% or below 1% the radiation of the visible spectrum passes unhindered through the material.

Due to the high radiation absorption, the flame bundle tube heats up considerably, so that it glows itself, i.e. it radiates in the visible spectral range. This means that more radiant heat can be emitted than if the same flames were visible from the outside through a transparent tube. There is therefore the surprising effect that an opaque shielding of the rising flames leads to a higher heat radiation of the radiation unit.

However, since a flickering optic of the radiant heater is pleasant to operate, the flame bundle tube has openings through which flames rising within the flame bundle tube are visible from the radially outside. A moving firelight is created, which can contribute to a beautiful mood. This applies in particular to a flame bundle tube made of a wire mesh, in which the spaces between the wires as openings make the flames appear visible from the outside.

The radiation unit does not have to, but is expediently oriented vertically upwards, so that a flue gas flue is directed vertically upwards through the radiation unit. The glass tube is transparent and expediently made of a ceramic glass or glass ceramic in order to maintain stability even at high temperatures and also to counteract breakage caused by thermal stresses. The term glass can be understood in this context for all transparent and temperature stable up to 800 ° C solid.

To separate ash from a flue gas stream, it is expedient if an ash collecting container is arranged in the flue gas stream after the blasting unit, expediently on the blasting unit. The blasting unit can open upwards into the ash collecting container, in which the fly ash is separated from the flue gas.

The solid fuel can be biomass. Biomass pellets, especially wood pellets, are particularly easy to convey. In order to achieve a continuous and energy-efficient combustion process, it is advantageous if the radiant heater has a conveying device for conveying solid fuel to the combustion unit. In this way, for example, a decreasing fuel level and thus changing combustion can be avoided. The delivery unit can range from the solid fuel storage to the combustion unit. A screw conveyor with a screw conveyor in a conveyor pipe is particularly suitable, in which the solid fuel can either be conveyed directly to the combustion unit by a rotation of the conveyor screw or can be conveyed to a location from which the fuel can fall into the combustion unit.

According to the invention, the radiant heater is a mobile radiant heater that can be transported manually as a whole, so that it can be moved simply by rolling, carrying or moving without impairing its function. Such a transfer is expediently also possible during the regular operation of the radiant heater.

In an advantageous embodiment of the invention, the flame bundle tube is a metallic tube. The metal can be sheet metal or wire, for example. It can be sufficient Temperature resistance can be achieved with simultaneous simple and inexpensive manufacture of the flame bundle tube. The flame bundle tube is expediently a continuous tube with one or more tube elements surrounding an inner flame space. The element or these elements are expediently flat elements, the surface orientation of which is free of inclination to the adjacent and parallel surface of the glass tube. In the case of several elements, their surface orientations are expediently aligned with one another. The tube element or elements are advantageously at least predominantly oriented vertically, the glass tube and the tube element or elements of the flame bundle tube advantageously forming two coaxial tubes.

The flame bundle tube advantageously extends within the glass tube at least over a lower quarter of the glass tube length. In this way, a lower area of the glass tube can be protected against overheating. The flame bundle tube expediently extends at least predominantly through the glass tube, in particular completely through the glass tube.

The flame bundle tube is expediently a continuous tube, in particular a metal tube. During operation, the flame bundle tube heats up to a red, orange or even yellow glowing state, so that a high heating output of the radiation unit can be achieved. The metal tube can be made from sheet metal or a wire arrangement, it extending in particular without interruption from the bottom up, possibly with the exception of openings, in particular circular openings in the otherwise continuous tube material. The flame bundle tube or its flat tube elements, if there are several, is expediently self-supporting. It is advantageously already a pipe at its lower end or lower connection. In order to obtain the most uniform possible temperature distribution of the glass tube, it is advantageous if the flame bundle tube is arranged concentrically in the glass tube. The flame bundle tube is expediently spaced all around from the glass tube, expediently over its entire length. In this way, air insulation can be achieved between the very hot flame bundle tube and the glass tube to be kept cool.

The area of the openings is expediently at least a quarter of the surface of the flame tube. As a result, a pleasant radiation output can be achieved even in an early operating stage when the flame bundle tube is still relatively cool overall. In continuous operation, a ratio of openings to closed areas between 5% and 40%, in particular between 10% and 20%, is advantageous.

The flame bundle tube advantageously comprises a perforated sheet metal tube with openings which are in particular arranged regularly with respect to one another. In this way, a uniform heat distribution in the environment can be achieved. It is also possible to increase the ratio of perforated area to sheet metal area upwards. This allows the glass tube to be protected in the lower area, whereas in the upper area the flames can give off their radiant heat directly to the outside.

In order to drive the flames far up through the radiation unit, a strong flow of combustion air is required, which is fed to the combustion in the combustion chamber. A flame guide reaching high through the flame bundle tube can be supported by a fan which pushes or pulls combustion air through the flame bundle tube.

The strong air flow and the flames reaching as far up as possible mean that the ash formed in the combustion chamber is largely carried away with the flames and the air flow upwards. It flies from the bottom upwards through the radiation unit and can be collected in an ash collector at the upper end of the radiant heater. It cannot be avoided that part of the fly ash settles on the glass tube, so that it becomes increasingly blunt and less transparent over time. The energy radiation of the radiation unit by visible light from the flames is thereby reduced over time.

Alternatively or in addition to a sheet metal tube, the flame bundle tube can be a wire tube made of a plurality of wires arranged in parallel to one another, in particular stainless steel wires. The wires can form a wire mesh, a wire mesh, a wire mesh or another wire envelope shape, such as, for example, from wires which are only arranged parallel to one another and which can be tacked together. A wire structure heats up quickly due to the flames, takes on the flame color and thereby optically moves into the background, so that its glowing part is hardly visible from the outside. The wire is advantageously a stainless steel wire, in particular with a thickness of up to 0.8 mm, in particular less than 0.6 mm.

In order to keep contamination of the glass tube as low as possible, it is advantageous to cover the radial openings with an ash filter, for example with a wire mesh. The mesh size of the ash filter is expediently adapted to the average size of the ash particles carried by the flame bundle tube and is in particular smaller than the average particle size, so that such particles do not fit through the mesh. A mesh size of 0.5 mm to 2 mm is advantageous.
or be in contact with the flame bundle tube from the inside. A flue gas flow is braked relatively little in the interior of the flame bundle tube, so that the flames are largely prevented from being dampened.

In order to load an intermediate space between the glass tube and the flame bundle tube with as little ash flight as possible, this intermediate space is closed at the bottom in such a way that flames rising from below can only enter the intermediate space from the inside to the outside through radial openings in the flame bundle tube.

The larger a flue gas stream that penetrates the flame bundle tube from the inside out, the more the flue gas stream within the flame bundle tube is weakened by the turbulence caused by the penetration. It is therefore desirable if the flue gas and the flames pass through the openings in the flame bundle tube as little as possible. Such passage can be reduced if a gap between the glass tube and the flame bundle tube is closed at its upper and / or lower end. The intermediate space is expediently closed in such a way that rising smoke gases can only enter and / or exit through radial openings in the flame bundle tube. A parallel flow through the intermediate space from bottom to top is largely prevented as a result, since the flow resistance is relatively high when the openings of the flame bundle tube are passed twice, in particular.

To achieve a high heat radiation output, it is advantageous if the flames strike as high as possible inside the flame bundle tube. For this purpose, it is advantageous if the flame bundle tube has an inside diameter between 40 mm and To achieve a high heat radiation output, it is advantageous if the flames strike as high as possible inside the flame bundle tube. For this it is advantageous if the flame bundle tube has an inner diameter between 40 mm and 90 mm, in particular between 50 mm and 75 mm. With such diameters, suitable heating capacities with good efficiency can be achieved for the catering sector. The glass tube can have an inner diameter between 80 mm and 200 mm, in particular between 110 mm and 150 mm.

The inner diameter of the flame bundle tube is advantageously in the range between 0.4 times and 0.85 times the inner diameter of the glass tube, in particular between 0.4 times and 0.65 times, further in particular between 0.45 times and 0.5 times. The glass tube and in particular the flame bundle tube are expediently cylindrical, so that their diameter is uniform over the height of the radiation unit. Otherwise the average diameter can be used.

If a wire structure is used as a flame bundle tube, it may have only low mechanical stability, especially in the glowing state. The stability can be maintained to a sufficient degree if the wire structure hangs within the glass tube, that is to say is held at its upper end. For this purpose, it can be clamped between two elements of the radiation unit and / or the roof unit. The wire mesh can be free at its lower end, similar to the sheet metal tube FIG 5 . In order to prevent a corrugation during operation, it is advantageous if the wire mesh is braced downwards, for example with one downwards hanging weight, such as a metal ring or two metal units, between which the lower end of the wire mesh is clamped.

In the case of a standing wire structure, the stability can be achieved by a plurality of wires, the diameter of which is larger than that of the neighboring wires, so that these form a type of stand on which the thinner wires hang.

Adequate stability combined with a low weight and high radiation performance can be achieved if the glass tube of the radiation unit has a glass thickness between 8 mm and 16 mm.

During the operation of the radiant heater, the temperatures within the radiation unit change significantly. It is therefore advantageous if the flame bundle tube is fastened within the radiation unit in such a way that thermal expansion is readily possible. This is achieved according to the invention if the flame bundle tube is at the bottom and can still freely expand at the top or is suspended in a supporting unit in its upper end and is at least axially freely movable at least axially at the bottom. A thermal linear expansion can take place without any problems, without the radiation unit being subjected to thermal stresses. The supporting unit is advantageously a roof unit, in particular an ash collecting container.

A sufficient radial degree of freedom for temperature expansion can be achieved if the flame bundle tube has spacers in its uppermost or lowermost third, depending on the suspension, which spaced it from the glass tube, purpose-made flame bundle tube the glass tube around the flame bundle tube can be dispensed with, so that the flame bundle tube is the outer tube, in particular the only tube of the radiation unit that carries flue gas. This is possible, in particular, when the flame bundle tube is made from a wire mesh, since here the escape of flue gas from the wire structure can be kept low.

The invention also relates to a method for operating a radiant heater according to the invention, in which solid fuel is burned in a combustion unit of a radiant heater and combustion heat is emitted into the surroundings of the radiant heater with a radiation unit, combustion gases resulting from the combustion through the opaque flame tube inside a glass tube of the radiation unit be performed.

In order to achieve safe operation with a high heating output, it is proposed that, according to the invention, flue gases resulting from the combustion are passed through a flame bundle tube within a glass tube of the radiation unit, in particular an opaque flame bundle tube, such as a metallic flame bundle tube.

In order to achieve a high heat radiation output, the flame bundle tube should glow over a long distance, expediently orange in the lower area and red in the middle area, the lower area being up to 20% of the length and the middle area being 20% to 70% of the length of the Flame bundle tube extends and the color red also includes dark red tones visible to the eye.

In order to achieve an annealing of the flame bundle tube, the combustion of the fuel gases should as far as possible not in one Combustion chamber of the combustion unit instead take place in the flame bundle tube. In the combustion chamber, on the other hand, wood gasification should occur when burning wood, for example wood pellets take place so that at least a large part of the wood gases only ignite in the flame bundle tube.

In order to achieve this, it is proposed that the combustion be supplied with fresh air by means of a blower, which is blown as primary air into the primary flame zone and as secondary air via the primary flame zone into a combustion chamber, and the ratio of secondary air to primary air is at least 1.5 . Due to the relatively low blowing rate of primary air, a large part of the wood gases leaves the primary flame zone unburned and can thus reach a secondary flame zone into which the secondary air is blown. The secondary flame zone is expediently located in the lower region of the flame bundle tube, so that the combustion takes place there. Accordingly, it is advantageous if the secondary air is blown in directly at the lower end of the flame bundle tube, where a distance of at most one diameter of the flame bundle tube can be understood, in particular a maximum of half the diameter of the flame bundle tube.

• mit p: Einstellparameter, A: Querschnitt des Flammbündelrohrs
• und l: Länge des Flammbündelrohrs. Der Einstellparameter liegt zweckmäßigerweise zwischen 0,8 und 2, insbesondere zwischen 1 und 1,5.

In order to drive the flames as far as possible through the flame bundle tube, an air volume flow that is blown into the combustion unit should be sufficiently large. When burning wood pellets, it is advantageous if in normal operation an air volume V is driven through the flame bundle tube with the size $$V=p\frac{m}{s}\sqrt{A}\ast l$$

• with p: setting parameters, A: cross section of the flame bundle tube
• and l: length of the flame bundle tube. The setting parameter is expediently between 0.8 and 2, in particular between 1 and 1.5.

Surprisingly, this relation does not include the volume A x l of the flame bundle tube linearly, but with the root of the cross-sectional area A of the flame bundle tube. The larger this cross-sectional area, the slower the average velocity of the combustion gases through the flame bundle tube if the same, good heat radiation from the flame bundle tube is to be achieved. Of course, the fuel supply should be adapted to the volume flow of the fresh air supply so that the combustion is as complete and hot as possible.

With a size of the radiant heater suitable for the catering sector, for example for heating tables in a garden, it is advantageous if, when burning wood pellets, fresh air is supplied with a blower in such a way that the combustion gases from the combustion occur at a medium speed of at least 1.4 m / s through the flame bundle tube. The flame bundle tube is made to glow extensively and good radiation heat is achieved.

The description given so far of advantageous refinements of the invention contains numerous features which are summarized in several dependent claims. However, these features can expediently also be considered individually and combined into useful further combinations, in particular when claims are referred back, so that a single feature of a dependent claim can be combined with a single, several or all features of another dependent claim. In addition, these features can be combined individually and in any suitable combination, both with the method according to the invention and with the device according to the invention according to the independent claims. So process features are also a property to see the corresponding device unit objectively formulated and functional device features also as corresponding process features.

The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, become clearer and more clearly understandable in connection with the following description of the exemplary embodiments, which are explained in more detail in connection with the drawings. The exemplary embodiments serve to explain the invention and do not limit the invention to the combination of features specified therein, not even with regard to functional features. In addition, suitable features of each exemplary embodiment can also be considered explicitly in isolation, removed from one exemplary embodiment, incorporated into another exemplary embodiment to supplement it and / or combined with any of the claims.

FIG 1

einen Heizstrahler mit einer tragenden Konstruktion, innerhalb dessen eine Brenneinheit angeordnet ist, und einer darauf angeordneten Abstrahleinheit mit einem Glasrohr, über der ein Aschesammelbehälter angeordnet ist,

FIG 2

den Heizstrahler aus FIG 1 in einem Querschnitt von oben,

FIG 3

den Heizstrahler aus FIG 1 in einem Längsschnitt von der Seite,

FIG 4

das obere Ende der Abstrahleinheit in einem Längsschnitt mit einem in den Aschesammelbehälter eingehängten Flammbündelrohr,

FIG 5

das untere Ende des Flammbündelrohrs in einem Längsschnitt unmittelbar oberhalb der Brenneinheit,

FIGs 6 und 7

ein alternatives oberes und unteres Ende der Abstrahleinheit in einem Längsschnitt mit einem stehenden Flammbündelrohr,

FIG 8

das von einem Drahtgitterrohr umgebene Flammbündelrohr und

FIG 9

ein Flammbündelrohr aus einem Drahtgewebe.

Show it:

FIG. 1

a radiant heater with a supporting structure, within which a combustion unit is arranged, and a radiation unit arranged thereon with a glass tube, over which an ash collecting container is arranged,

FIG 2

the radiant heater FIG. 1 in a cross section from above,

FIG 3

the radiant heater FIG. 1 in a longitudinal section from the side,

FIG 4

the upper end of the blasting unit in a longitudinal section with a flame bundle tube suspended in the ash collecting container,

FIG 5

the lower end of the flame bundle tube in a longitudinal section immediately above the combustion unit,

6 and 7

an alternative upper and lower end of the radiation unit in a longitudinal section with a standing flame bundle tube,

FIG 8

the flame bundle tube surrounded by a wire mesh tube and

FIG. 9

a flame tube made of wire mesh.

FIG. 1 shows a radiant heater 2 with a supporting structure 4 and a radiation unit 6 arranged thereon. The radiation unit 6 is surrounded by a protection unit 8 in order to counteract combustion by touching the radiation unit 6. A roof unit 10 is arranged on the radiation unit 6, which in the exemplary embodiment shown is an ash collecting container. The roof unit has outlet openings 12 for discharging the flue gases into the environment.

The radiant heater 2 is a mobile radiant heater with a height of between 2.0 m and 2.5 m, which includes wheels 14 for easy movement, for example on a terrace or a meadow, below the supporting structure 4 or as part thereof.

In FIG. 1 the protection unit 8 is shown as a transparent unit through which the radiation unit 6 is visible. As a general rule The protective unit 8 can be a grid, for example a wire mesh, a perforated plate with a sufficient number or sufficiently large openings or another protective unit which is as metallic as possible, through which the thermal energy radiated radially outwards by the radiation unit 6 can easily pass. The protection unit 8 should heat up as little as possible in order not to represent a source of danger when touched.

FIG 2 shows the mobile radiant heater 2 in a cross section from above, and FIG 3 shows it in a longitudinal section from the side. The position of the respective other cross-section is indicated in both figures by the dash-dotted line. The load-bearing structure 4 and a solid fuel storage 16 arranged in it can be seen in both figures. In order to be able to fill this more easily with solid fuel, such as biomass pellets, in particular wood pellets, an in FIG 3 shown rear wall 18 removable, so that the solid fuel storage 16 is easily accessible, as from FIG 3 you can see.

A conveyor device 20 with a screw conveyor 22 projects into the solid fuel storage unit 16 from above. A tube around the screw conveyor 22 is open at the bottom, so that the pellets located in the solid fuel store 16 can press into the screw conveyor 22 from below. By rotating the screw conveyor 22 in the tube fixed to the housing, the pellets are conveyed upwards until they reach an opening 24 through which they fall obliquely downwards into a combustion unit 26. They fall onto a burner plate 28 in a combustion chamber 30, where they burn. The hot combustion gases 32 formed from the combustion flow through an upper opening 34 of the combustion unit 26 into the radiation unit 6, as by the two dashed arrows in FIG FIG 3 is shown. The combustion gases 32 flow through the roof unit 10 and leave it through the outlet openings 12 into the environment.

In the case of the radiant heater 2, the combustion unit 26 can be removed particularly easily from a housing 38 which partially radially surrounds the combustion unit 26. In FIG 3 The combustion unit 26 is shown in two versions. On the right, it is fastened within the housing 38 in the radiant heater 2. It is removed on the left and turned upside down so that the ash collected in it can be poured into an ash container 40, for example a metal bucket. For this purpose, the combustion unit 26 contains a handle 42 by which it can be easily removed from the housing 38. The ash falls out through the upper opening 34 into the ash container 40. The ash can also fall out through a filler neck 44. If the ashes have collected in a space 46 between a burner housing 48 and the inner housing of a burner 50 because they came in through primary air openings 52 or secondary air openings 54 during operation, the ashes can escape from the space 46 through lower openings 56.

The firing unit 26 is fastened to a burner mounting 58, of which the firing unit 26 can easily be seen in FIG FIG 2 can be subtracted by an arrow 60. For this purpose, the burner suspension 58 comprises two bolts 62, onto each of which a sleeve 64 is pushed.

How out FIG 3 can be seen, the radiation unit 6 is constructed with two shells. Arranged in an outer wall, which is formed by a glass tube 66, is a flame bundle tube 68, which is a metallic tube, for example made of a perforated plate with a multiplicity of openings 70. Such breakthroughs are, for example, in FIG 4 shown. For an exit To prevent ash through the flame tube 68 into an intermediate space 72 between the wall 66 and the flame tube 68, the openings in the flame tube 68 can be blocked with a wire mesh. This is in FIG 8 shown.

To operate the radiant heater 2, the solid fuel storage 16 is filled with solid fuel, for example wood pellets, and the fuel is conveyed into the combustion unit 26 by the conveying device 20 until a desired fill level is reached. Alternatively, the combustion unit 26 can be partially filled with fuel manually. The fuel is then lit with a fireplace lighter.

To supply combustion air, a blower 76 is controlled by a control unit 74, which blows fresh air or combustion air into an overpressure chamber 78 via an air supply. The overpressure chamber 78 is arranged directly on the combustion unit 26 and has two openings which merge directly into the openings 56 of the combustion unit 26, so that combustion air is blown into the combustion unit 26 or its space 46. The space 46 extends radially around the burner 50, so that there is an overpressure in this space 46 relative to the surroundings. The combustion air presses out of the intermediate space 46 through the primary air openings 52 below and the secondary air openings 54 further up in the inner housing of the burner 50 into its interior or combustion chamber 30, where it fuses the combustion.

In order to achieve a good radiation effect of the radiation unit 6, the combustion is controlled by controlling the combustion air and the fuel supply into the combustion chamber 30 in such a way that its flames reach far up through the radiation unit 6 are enough. This causes such a train through the combustion chamber 30 that the ashes resulting from the combustion are mostly torn as fly ash upwards and through the radiation unit 6. It takes the path drawn by the two dashed arrows through the radiation unit 6 and into the roof unit 10. In general, the hot flue gas in the roof unit 10 or in the ash collecting container is deflected into a curved path by a deflection unit such that the fly ash is separated downward . The flue gas cleaned in this way emerges through the outlet openings 12 and is oriented laterally and obliquely downward from the ash collecting chamber into the environment.

The setting of the volume flow of the secondary air to the primary air is achieved by the number and size of the primary air openings 52 and the secondary air openings 54. In the exemplary embodiment shown, twice as much secondary air is blown in as primary air. As a result, the combustion is divided into two zones, a primary combustion zone in the region of the combustion chamber 30 and a secondary combustion zone above the secondary air openings 54, which is largely in the flame bundle tube 68. As a result, wood gasification takes place in the combustion chamber 30, a large part of the wood gases igniting and burning only within the flame bundle tube 68. The flames strike far high in the flame bundle tube 68, which thereby glows orange in a lower region up to approx. 25% of its length and glows at least red in a central region up to approx.

As in FIG 3 can be seen, air is also blown into the conveying device 20, which for this purpose has an opening in the area of the pressure chamber 78, into which the air flows and flows into the combustion chamber 30 via the filler neck 44. This influx prevents backburning through the filler neck 44 from the combustion chamber 30 into the conveying device 20. If this air flow is also included, the air flow previously referred to as the secondary air flow can be referred to as the tertiary air flow, the relationships to the primary air flow being understood without the conveying device air flow or secondary air flow.

• mit V: Gesamtvolumenstrom durch das Flammbündelrohr 68,
• p = 0,13, A = (3 cm)² x π und l = 100 cm. Es ergibt sich ein Gasstrom durch das Flammbündelrohr 68 von V = 25 m³/h und eine Gasgeschwindigkeit durch das Flammbündelrohr 68 von 2,5 m/s unter Vernachlässigung einer Strömung im Zwischenraum 72.

The total air flow is adjusted by the delivery volume of the combustion air blower 76. The setting is made according to the relation $$V=p\frac{m}{s}\sqrt{A}\ast l$$

• with V: total volume flow through the flame bundle tube 68,
• p = 0.13, A = (3 cm) ² x π and l = 100 cm. The result is a gas flow through the flame bundle tube 68 of V = 25 m ³ / h and a gas velocity through the flame bundle tube 68 of 2.5 m / s, neglecting a flow in the intermediate space 72.

FIG 4 shows the upper end of the radiation unit 6 under the roof unit 10. The upper end of the glass tube 66 and the flame bundle tube 68 can be seen. The roof unit 10 has a downwardly projecting radial support 80, within which the upper end of the glass tube 66 is arranged. The glass tube 66 is in this case spaced from a floor 82 of the roof unit 10 by several millimeters, so that it can "grow" when it is thermally heated up, without hitting the floor 82. As a result, thermal stresses in the glass tube 66 can be kept low. Additionally or alternatively, the roof unit can be attached to the protective unit 8 in such a way that it can move upwards and can "grow" with an expansion of the glass tube 66.

FIG 5 shows the radiation unit 6 at its lower end. The approx. 5 mm thick glass tube 66 stands down on a floor 84 of the radiation unit 6 freely. Radially, it is surrounded by a support 86 which, like the support 80, holds it radially in position at the top. However, with both supports 80, 86 there is a distance of several millimeters around the inner glass tube 66 in order to enable its thermal expansion.

The flame bundle tube 68 is arranged within the glass tube 66. In this exemplary embodiment, the flame bundle tube 68 extends completely through the glass tube 66 in its axial length. How out FIG 4 can be seen, the flame bundle tube 68 is radially widened at its upper end and includes, for example, a collar 88. With this radial widening, the flame bundle tube 68 forms a positive connection with the roof unit 10, for example the bottom 82 of the roof unit 10, as in FIG FIG 4 is shown. The collar 88 lies radially around the flame bundle tube 68 on the floor 82, so that the flame bundle tube hangs downward on the floor 82 or another element, generally on the roof unit 10.

The lower end of the flame bundle tube 68 is in the axial direction, as in FIG FIG 5 is shown, freely movable. It is free through an opening of the bottom 84 of the radiation unit 6 downwards, so that it can expand thermally freely downwards. In this respect, the glass tube 66 can freely expand upwards and the flame bundle tube 68 downwards. Also radially the lower end of the flame bundle tube 68 - like in particular the upper end - is spaced a few millimeters from the bottom 84, 82, so that thermal expansion is also possible in this radial direction without mechanical stresses being built up.

In the embodiment from the 6 and 7 the upper collar 88 is missing. Instead, the flame bundle tube 68 is at the bottom with a lower collar 89, and the flame tube 68 is axially expandable in this respect. The radial mounting of the flame bundle tube 68 is analogous to the previous exemplary embodiment, although it is alternatively possible for the flame bundle tube 68 to have metallic shapes or noses in its upper region which support it radially on the glass tube 66 instead of or in addition to the base 82 of the roof unit 10 .

The inner diameter of the flame bundle tube 68 is less than half the inner diameter of the glass tube 66, so that a relatively large space 72 is formed between the glass tube 66 and the flame bundle tube 68. Suitable sizes are 60 mm inner diameter of the flame bundle tube 68 and 130 mm inner diameter of the glass tube 66 with a sheet thickness of 1 mm and a glass thickness of 5 mm.

The flame bundle tube 68 has a multiplicity of openings 70, through which the interior of the flame bundle tube 68 receives an air connection with the intermediate space 72. The area of the openings 70 accounts for approximately 25% of the surface of the flame bundle tube 68. In the in the 4 and 5 In the example shown, the flame bundle tube 68 is made from a perforated plate which has a multiplicity of openings 70 which are in particular arranged regularly with respect to one another. An irregular arrangement and / or irregularly large openings 70 are also possible.

During the operation of the radiant heater 2, flames blow out of the combustion unit 26 through the opening 34 from below into the radiation unit 6. They hit the inside of the flame bundle tube 68 and are generated by their own thermals, possibly increased by a fan pressure difference from bottom to top in Flame bundle tube 68, through the flame bundle tube 68 driven upwards, for example up to about half or even completely through the flame bundle tube 68. The flame region of the fire is bundled through the flame bundle tube 68 onto the inside of the radiation unit 6, so that the flames thereby strike higher in the radiation unit than without the flame bundle tube 68. The flames heat up the flame bundle tube 68, so that it has an increasing temperature from top to bottom and lights up to glowing orange in the lower region. This supports the optics of the flames and the glowing area of the flame bundle tube 68 optically fades into the background.

The flue gas 32 flows through the flame bundle tube 68 and, during regular operation of the radiant heater 2, still has a temperature of more than 500 ° C. at its upper end. As a result, the radiation unit 6 also radiates strongly thermally in its upper region. On its way through the flame bundle tube 68, the flue gas 32 cools down from a temperature above 1000 ° C. at the lower end of the flame bundle tube 68 to, for example, an average temperature between 500 ° C. and 700 ° C. at its upper end. The lost energy is radiated into the environment as heat.

Due to the rapid gas flow of the flue gas 32, a lot of fly ash in the flue gas flow is carried upwards through the flame bundle tube 68. This should be kept as far as possible from the glass tube 66 so that it does not settle on it and the glass tube 66 becomes dull during operation and allows less radiant heat to pass through. For this purpose, it makes sense if the flue gas flow remains as concentrated as possible in the flame bundle tube 68 and flows as little as possible outside of the flame bundle tube 68. This can be achieved in that the lower entrance of the glass tube 66 is at least largely closed radially outside the flame bundle tube. Such a closure 90 is in FIG 5 shown. The bottom 84 protrudes radially from the outside into the vicinity of the flame bundle tube 68 and thus largely closes the entrance to the intermediate space 72 from below. The flames emerging from the opening 34 are largely forced to strike the interior of the flame bundle tube 68. In the embodiment FIG 7 this closure is even tighter. The flame bundle tube 68 stands up at the bottom and closes the space 72 at the bottom twice: through the base 84 and the lower base, on which the lower collar 89 stands.

For the same reason, the intermediate space 72 is largely closed at the top. Here, too, a bottom 82 of the roof unit 10 forms a closure 92, which largely closes the space 72 upwards. This closing is limited by the play between the glass tube 66 and the attic 82. Combustion gases can get through the openings 70 of the flame bundle tube 68 into the intermediate space 72. However, since they have to flow back through the openings 70 into the interior of the flame bundle tube 68, this is associated with a high flow resistance, so that the proportion of the combustion gases flowing through the openings 70 is relatively small.

FIG 8 shows an embodiment in which the space 72 and the glass tube 66 are further protected from fly ash. At the in FIG 8 Flame bundle tube 68 shown, the openings 70 are covered by a wire mesh tube 94. The wire mesh tube 94 is placed from the outside around the cylindrical part of the flame bundle tube 68. It comprises a wire mesh - no distinction is made in the following between fabric and mesh - with a mesh size that is smaller than the average diameter of the ash particles passing through the flame bundle tube 68. As a result, the flames remain visible from the outside, and the flue gas 32 can also be limited Pass the flame bundle tube 68 circumferentially into the intermediate space 72.

The wire mesh acts as an ash filter, which retains the fly ash in the interior of the flame bundle tube 68. The wire mesh tube 94 is wrapped around the outside of the flame bundle tube 68 in order to brake the flue gas flow along the inner wall of the flame bundle tube 68 as little as possible. If it is created on the inside, the look of the flame bundle tube 68 is more beautiful. On the outside, the wire mesh tube 94 extends over more than 90% of the length of the flame bundle tube 68. It covers all the openings 70 in the flame bundle tube 68.

FIG. 9 shows an alternative flame bundle tube 68a, which is formed by a wire mesh. The wire mesh is woven from a stainless steel wire with a thickness of about 0.5 mm, so that it quickly heats up due to the flames and takes on the flame color. As a result, it optically takes a back seat so that its glowing part is hardly visible from the outside.

The wire mesh is clamped at its upper end between a ring 98 and the bottom 82 of the roof unit 10, which are screwed together, for example. At its lower end, the wire mesh swings freely within the support 86. It is clamped at its lower end between two short tubular cylinders which are fitted into one another and hold the wire mesh in a radial space between them. A cylinder is thus attached to the outside of the flame bundle tube 68a and a cylinder inside. The two weight elements are welded to one another and to the wire mesh and are freely suspended within the support 86.

To reduce curl or back-and-forth swinging in operation, the flame bundle tube 68a may include stiffening wires 96 have greater thickness, for example 2 mm, which are attached to the wire mesh, for example woven or welded. They are also expediently clamped in at the top and bottom with the wire mesh.

At one to the 6 and 7 Analogous embodiment, the wire mesh stands up and is held up by the stiffening wires 96. Radial deformation can be counteracted by one or more rings which are connected to the wire mesh in particular at the top, but expediently also in the central region of the flame bundle tube 68a.

When wire is used essentially alone to form the flame bundle tube 68a, a wire mesh, wire mesh or other wire formation can be used, generally referred to as wire structures. Thus, only vertical wires can form the flame bundle tube 68a, which are held together with rings, for example.

Reference symbol list

2nd

Radiant heater

4th

load-bearing construction

6

Radiation unit

8th

Protection unit

10th

Roof unit

12

Outlet opening

14

wheel

16

Solid fuel storage

18th

Back wall

20th

Conveyor

22

Auger

24th

opening

26

Firing unit

28

Burner plate

30th

Combustion chamber

32

Combustion gas

34

opening

38

casing

40

Ashtray

42

Handle

44

Filler neck

46

Space

48

Burner housing

50

burner

52

Primary air opening

54

Secondary air opening

56

opening

58

Burner mounting

60

arrow

62

bolt

64

sleeve

66

Glass tube

68, 68a

Flame bundle tube

70

breakthrough

72

Space

74

Control unit

76

fan

78

Hyperbaric chamber

80

Support

82

ground

84

ground

86

Support

88

collar

89

collar

90

Clasp

92

Clasp

94

Wire mesh tube

96

Stiffening wire

98

ring

Claims (13)

1. Mobile radiant heater (2) having a combustion unit (26) for the combustion of solid fuel, having a solid fuel store (16), having a transparent radiating unit (6) for radiating combustion heat into the surroundings, having a flue gas pipe which is directed vertically upwards through the radiating unit (6), and having a roof unit (10) which is arranged on the radiating unit (6), wherein the radiating unit (6) has a glass tube (66) and an opaque flame-concentrating tube (68) arranged in the glass tube (66),
   characterized
   in that the radiating unit (6) has a base (84) and a lower base, wherein the flame-concentrating tube (68) runs through an opening of the base and comprises a lower collar (89) by means of which it stands on the lower base, wherein the base (84) projects from radially outside into the vicinity of the flame-concentrating tube (68), or
   in that the flame-concentrating tube (68) comprises an upper collar (88) by means of which it forms a form fit with the roof unit (10), such that the flame-concentrating tube (68) hangs on the roof unit (10) .
2. Radiant heater (2) according to Claim 1,
   characterized
   in that the flame-concentrating tube (68) is a metallic tube which extends within the glass tube (66) in the flue gas flow direction through at least the predominant part of the glass tube (66).
3. Radiant heater (2) according to Claim 1 or 2,
   characterized
   in that the flame-concentrating tube (68) is arranged concentrically in the glass tube (66), extends all the way through the glass tube (66), and is spaced apart from the latter all the way around.
4. Radiant heater (2) according to any of the preceding claims,
   characterized
   in that the flame-concentrating tube (68) has apertures (70) through which flames rising within the flame-concentrating tube (68) are visible from radially outside.
5. Radiant heater (2) according to any of the preceding claims,
   characterized
   in that the flame-concentrating tube (68) is a perforated sheet-metal tube with, in particular, apertures (70) arranged in a regular manner with respect to one another.
6. Radiant heater (2) according to any of the preceding claims,
   characterized
   in that the flame-concentrating tube (68) comprises a wire tube (94) composed of a multiplicity of wires arranged parallel to one another.
7. Radiant heater (2) according to any of the preceding claims,
   characterized
   in that the flame-concentrating tube (68) is a metallic tube, around the outside of which a wire mesh (94) is laid.
8. Radiant heater (2) according to any of the preceding claims,
   characterized
   in that the flame-concentrating tube (68a) is formed by a wire gauze (94) composed of high-grade steel wire with a wire diameter of less than 0.8 mm.
9. Radiant heater (2) according to any of the preceding claims,
   characterized
   in that the diameter of the flame-concentrating tube (68) lies in the range between 0.4 times and 0.65 times the glass tube (66).
10. Radiant heater (2) according to any of the preceding claims,
    characterized
    in that the glass tube (66), at its lower end, stands on a base (84) and is radially movable and, at its upper end, stands so as to be both radially and axially movable.
11. Method for operating a radiant heater (2) according to any of the preceding claims, in which method solid fuel is combusted in a combustion unit (26) of the radiant heater (2), and combustion heat is released into the surroundings of the radiant heater (2) by means of a radiating unit (6), wherein combustion gases (32) arising from the combustion are conducted through an opaque flame-concentrating tube (68) within a glass tube (66) of the radiating unit (6).
12. Method according to Claim 11,
    characterized
    in that fresh air is fed to the combustion by means of a blower (76), which fresh air is blown as primary air into the primary flame zone and as secondary air over the primary flame zone, and the ratio of secondary air to primary air amounts to at least 1.5.
13. Method according to either of Claims 11 and 12,
    characterized
    in that wood pellets are burned, and fresh air is fed to the combustion by means of a blower (76) such that the combustion gases from the combustion are driven through the flame-concentrating tube (68) at an average speed of at least 1.4 m/s.

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