EP3343106B1 - Heating appliance with a nozzle assembly for after burning - Google Patents

Description

I. Field of application

The invention relates to a heating device for solid fuels such as wood, and specifically the primary extraction for the flue gases from the primary combustion chamber into a downstream afterburning chamber.

II. Technical background

• In der primären Brennkammer wird zwar ein Großteil des festen Brennstoffes verbrannt, jedoch enthalten die dort entstehenden Rauchgase noch einen großen Anteil an kohlenstoffhaltigem, brennbarem Gas, welches noch verwertbar ist. Deshalb werden die Rauchgase einer Nachbrennkammer zugeführt und dort - mit zusätzlich zugeführter Verbrennungsluft, der Sekundärluft - nachverbrannt, um die Ausnutzung des Brennstoffes und damit die Effizienz der Heizvorrichtung zu erhöhen.

It is known to carry out a combustion - also of solid fuels such as wood - in several stages:

• A large part of the solid fuel is burned in the primary combustion chamber, but the flue gases produced there still contain a large proportion of carbon-containing, combustible gas which can still be used. For this reason, the flue gases are fed to an afterburning chamber and there - with additional combustion air, the secondary air - afterburning in order to increase the utilization of the fuel and thus the efficiency of the heating device.

It is also known to allow the flue gases to flow through a nozzle arrangement in the primary exhaust of the flue gases from the primary combustion chamber to the afterburning chamber and to supply the secondary air, i.e. the additionally required combustion air - possibly also recirculated flue gas, - whereby a good mixing of the Flue gases with the secondary air and thus a very complete combustion of the combustible components in the flue gas takes place in the afterburning chamber.

The primary vent often consists of a kind of grate - even if it is vertical because the flow direction in the primary vent is horizontal - of hollow profiles arranged next to one another at a distance, through the interior of which the secondary air is supplied and is released through outlet openings into the passages between the hollow profiles. These passages are preferably narrowing passages due to the cross-sections of the hollow bodies increasing in the flow direction and act as a nozzle so that the acceleration of the flue gases that occurs automatically sucks the secondary air into the flue gas flow without an additional fan or the like.

• Die Strömungsgeschwindigkeit sollte möglichst hoch sein, um aus den Austrittsöffnungen der Hohlprofile möglichst viel Sekundärluft selbsttätig anzusaugen.

The flow velocity of the gas mixture in the passage is a very critical variable:

• The flow velocity should be as high as possible in order to automatically suck in as much secondary air as possible from the outlet openings of the hollow profiles.

On the other hand, the flow velocity must not exceed a certain limit value, as otherwise the flame reaching through the primary exhaust with the flue gases will break off and the combustion in the afterburning chamber will initially be interrupted, usually restarted a short time later by a deflagration, which must be avoided is applicable.

• Die Menge an Brenngas hängt natürlich zum einen ab von der Menge an eingebrachtem Holz, aber darüber hinaus von anderen Faktoren, beispielsweise ob sich der Brennstoff gerade am Beginn der Verbrennung befindet und die Temperatur im Steigen begriffen ist, denn in dieser Phase werden in der Regel mehr Gase pro Zeiteinheit abgegeben als bei einem bereits vollständig glühenden Brennstoff.

The critical flow rate at which the flame breaks out depends on the temperature of the flame, and the overall flow rate depends, among other things, on the amount of fuel gases generated in the main combustion chamber:

• The amount of fuel gas depends on the one hand on the amount of wood brought in, but also on other factors, for example whether the fuel is just beginning to burn and the temperature is rising, because in this phase, as a rule more gases emitted per unit of time than with an already completely glowing fuel.

• So gibt Scheitholz am Anfang mehr Brenngas frei als beispielsweise die stark gepressten Pellets. Die nicht gepressten Hackschnitzel liegen hier etwa in der Mitte.

The type of fuel also influences gas development:

• In the beginning, split logs release more fuel gas than, for example, the heavily pressed pellets. The unpressed wood chips are roughly in the middle here.

It is also already known, for example from the DE 4435794 C2 that the side walls of these hollow profiles running in the direction of flow have an extension towards the rear at least over the areas of the back plate which are furthest forward. Similar heating devices with primary exhaust formed as hollow profiles are the DE102011117950 and the EP0809077 refer to.

This extension causes a reverse vortex of the flowing gas mixture to appear on the back of the hollow profile near the protrusions. The gases flowing in a laminar manner through the nozzle arrangement are swirled, so that the gas components, i.e. the flue gases with the secondary air, are particularly well mixed, which improves the completeness of the post-combustion.

The most complete possible afterburning of both the gaseous combustible constituents and the partially invisible small solid constituents in the flue gases is not only necessary in order to increase efficiency, but the fine dust content of the exhaust gases ultimately escaping from the heating device depends on it.

In this context it is from the US 5342592 It is already known to have hollow profiles extending transversely to the flow direction protrude into the exhaust gas flow of a combustion process in the form of round tubes which have outlet openings on their outer circumference in order to allow reactants supplied via the interior of these hollow profiles into the passages between the several parallel hollow bodies through which the external exhaust gas flow passes

The outlet openings are - in the flow direction of the exhaust gases passing through the grate made of hollow bodies - arranged at the widest point of the hollow profile.

It is also from the US 2014/0246522 A1 It is already known to let a gas laden with particles flow through a round tube, in the circumference of which there are openings with inward bends, so that parts of the gas flowing in the pipe can escape to the outside through these bends pointing against the inner flow direction with the front edge.

Since the regulations for the fine dust content of such solid heating devices are constantly being tightened, the fine dust content is an increasing problem due to its harmful effects.

At the same time, however, there can be no optimal heating device and also no optimal primary exhaust with which optimally complete combustion and optimally low fine dust content are generally achieved, because many parameters play here, such as the type of fuel, its moisture content, the amount of primary air and secondary air, the strength of the The negative pressure generated by the chimney, the altitude of the burning device, the prevailing weather conditions, etc. play a role, so that the heating device and in particular the primary exhaust must be individually adapted to these conditions in order to achieve optimal combustion, i.e. optimally low fines content and optimally high efficiency , to reach.

III. Presentation of the invention a) Technical task

It is therefore the object of the invention to provide a heating device and, in particular, a simple and inexpensive primary exhaust which enables the combustion to be optimized depending on the specific operating conditions of the heating device.

b) Solution of the task

This object is achieved by the features of claim 1. Advantageous embodiments emerge from the subclaims.

A generic primary vent of a heating device for solid fuels has a plurality of hollow profiles which are spaced apart from one another transversely to their directions of course, which preferably run parallel to one another.

The smoke gases pass through the at least one clear passage between two adjacent hollow profiles, whereby they are accelerated, since the clear passage between the adjacent hollow profiles represents a narrowing of the previous total flow cross-section and these clear passages act as nozzle slots.

Secondary air or recirculated flue gas is added to the flue gases, which are introduced into the interior of the hollow profiles and released to the flue gases flowing through through outlet openings that are arranged in the circumference of the hollow profile, preferably at the location of the nozzle slot, i.e. the clear passage.

With regard to the primary vent , the object is achieved in that the outer surfaces of the hollow profiles approach each other towards the rear from the widest point of the hollow profiles in the direction of flow in which the flue gases flow through the passage, i.e. against the longitudinal center plane of the hollow profile running in the direction of flow , approach and each end in a tear-off edge.

The two tear-off edges can have a smaller, equal or larger spacing in the transverse direction than the greatest width of the outer circumference of the hollow profile.

The back plate which connects the two tear-off edges and which forms the rear part of the hollow profile, which is usually in one piece, has a concave outer contour.

The hollow profiles are preferably designed symmetrically to their longitudinal center plane, which includes the direction of extent. If the hollow profiles are built into a primary exhaust, the direction of flow of the smoke gases flowing through the primary exhaust is also in or parallel to this longitudinal center plane.

Due to the - at least initially - mutual approach of the outer surfaces of the hollow profiles in their rear area and the ends in a spoiler edge, the tendency towards the formation of reversal eddies on the rear side of the obstacle, which is always present in terms of flow when passing through a nozzle, i.e. between two obstacles, is considered in the direction of the hollow profile - promoted, and these reversal eddies are specifically formed, in particular by the shape of the outer surfaces in the rear area of the hollow profile, which is why this is preferably convexly curved, as this works better than a flat course.

The formation of inverted eddies is further promoted by the concave rear side of the hollow profile, that is to say the concave outer contour of the back plate, which forms the rear part of the hollow profile.

The best possible development and stable shape of such swirls when the primary extractor is in operation ensures that the flue gases remain in the swirl for a long time and thus very good mixing of the flue gases passing through the primary extractor with the other gas supplied in the primary extractor, mostly secondary air, in order to optimize the afterburning. This increases the completeness of the combustion and at the same time reduces the number of particles present in the flue gases, in particular fine dust.

By varying the distance and / or the shape of the two tear-off edges from one another, and in particular the size of the lateral overhang over the widest point of the hollow profile, the type of turbulence and the shape of the reversing vortices that are formed can be determined.

The supply of secondary air or recirculated flue gases into the hollow profiles is preferably carried out via one of the end faces into the hollow profile.

The other end face is then of course tightly closed so that the hollow profiles only have one inlet opening for the secondary air and the outlet openings, usually a large number of outlet openings arranged in the direction of extent of the hollow profile on both sides in the side surfaces.

In the direction of flow, these outlet openings are preferably arranged in front of or at the latest at the widest point of the outer contour.

Another variant is to arrange these in the back plate, which experience has shown is not quite as efficient.

The shape of the trailing edge is of great importance for the optimal formation of the reversal eddy: it is preferably designed with a V-shaped cross-section, i.e. it forms a cutting edge in which the edge radius considered in the direction of the hollow profile and thus also the trailing edge is less than 2 mm , better is less than 1mm, better is less than 0.5mm, better is less than 0.3mm, better is less than 0.2mm.

The cutting edge angle, i.e. the angle of the V-shaped trailing edge viewed in cross-section, should be acute-angled, preferably less than 85 °, better less than 80 degrees, better less than 75 degrees, better less than 35 degrees, better less than 30 degrees.

It is also important that the rear side, i.e. the outer surface, of the back plate merges into this tear-off edge, which is designed as a cutting edge, and its outer contour without a shoulder and without a kink Kink radius of more than 2 mm, especially more than 4 mm, especially more than 6 mm.

Obviously, the curvature or curvature of the concave outer surface of the backplate also plays an important role. Preferably, their radius of curvature in absolute values should be between 0.5 cm and 5 cm, better between 0.8 cm and 4 cm, better between 1.0 cm and 3 cm, better between 1.3 cm and 2.5 cm, better between 1.4 cm and 2.0 cm.

In relation to the pipe diameter, if the hollow profile is a pipe with a circular cross-section, the radius of curvature of the outer surface of the concave back plate should not be more than 40%, better not more than 30%, better not more than 20% of the average radius of curvature of the outer contour of the hollow profile differ and / or in the case of a tubular profile with a circular cross-section, the radius of curvature of the concave curvature deviates from the radius of curvature of the outer contour of the tubular profile by no more than 20%, preferably no more than 10%, preferably no more than 5%.

The distance between the two tear-off edges of a hollow profile is also important, because this is supposed to promote the formation of two adjacent vortex vortices without these hindering each other too much.

Therefore, the distance should be between 30% and 60%, better between 35% and 55%, better between 40% and 50% of the greatest width of the outer contour of the hollow profile, in particular the outer diameter of the hollow profile designed as a round tube, measured in the transverse direction.

However, it can also be equal to or greater than the greatest width of the outer contour of the hollow profile, but preferably by no more than 10%, better no more than 20%, better no more than 30%.

These values, especially a combination of these values, have surprisingly turned out to be very effective in practice.

A very simple method of producing a hollow profile at least in its middle length range that is relevant for the mixing of gases - at the ends of the hollow profiles there is usually a support on a surrounding structure - is - especially if the hollow profile has a circular cross section - a to separate segment strips of the hollow profile extending in the course of the hollow profile out of this, and to reinsert them with its inside outwards into the resulting recess, and in particular to fix them tightly, preferably to weld them.

The desired concave outer surface of the back plate is then created and the connecting areas between the outer edges of the segment strip inserted and the end edges of the remaining pipe cross-section can be designed as a blade-shaped tear-off edge, as described above.

With this design, the gap between the front and rear end of the segment strip inserted in reverse and the inner circumference of the pipe is naturally also tightly closed by a sealing part inserted tightly there, preferably welded in, or by a corresponding deformation of the segment strip at its front ends. Such a hollow profile is preferably formed in one piece.

• Ein solches zweiteiliges Hohlprofil besteht aus einem Frontteil, welches ein im Querschnitt geschlossenes, vorzugsweise einstückiges, Hohlprofil bildet, und einem an der Rückseite, also der Rückenplatte dieses Frontteiles, lösbar befestigten und vorzugsweise einstellbaren Steuerprofil, welches vorzugsweise aus zwei Profil-Teilen besteht:
  • Jedes Profil-Teil ist vorzugsweise ein sich in Verlaufsrichtung des Hohlprofiles erstrecken des Winkelprofil, wobei ein Schenkel des Winkels entlang der Außenfläche der Rückenplatte verläuft und teilweise an dieser anliegt, und an dessen äußeren Ende der andere Schenkel ansetzt.

However, a two-part design enables better adaptation to the respective application, although the structural effort is significantly higher:

• Such a two-part hollow profile consists of a front part, which forms a preferably one-piece hollow profile, which is closed in cross section, and one on the rear side, that is to say the back plate of this front part, which is detachable attached and preferably adjustable control profile, which preferably consists of two profile parts:
  • Each profile part is preferably an angle profile extending in the direction of the hollow profile, one leg of the angle running along the outer surface of the back plate and partially resting against it, and the other leg attaching to its outer end.

The other leg has on its free end edge the tear-off edge for the flowing air, and this other leg forms an extension of the outer contour of the cross section of the front part towards the rear.

The outer contour of this leg lengthening the front part is preferably again concavely curved.

This angled control profile is preferably only in a region of the extent of the cross section of the first leg running along the back plate on the back plate, and can be pivoted with respect to this system by suitable means, such as an adjusting screw, whereby the angular position of the other Leg is pivoted and in particular the position of the tear-off edge formed thereon is changed to the front part.

The front part can have spaced apart in its direction of extension and protruding in the longitudinal direction, which protrude to the rear beyond the back plate and which engage in corresponding recesses of the control plate for its guidance in order to guide the control profile.

With regard to a heating device, this object is achieved by placing the primary exhaust between the combustion chamber and an afterburning chamber Heating device is arranged, and the primary exhaust is designed as described above.

The primary vent preferably has a plurality of rows of hollow profiles that are spaced apart in the direction of flow and that are adjacent to one another transversely to the direction of flow, the rows being arranged in such a way that, viewed in the direction of flow, the hollow profiles of one row run transversely to the hollow profiles of the adjacent row of hollow profiles, i.e. viewed in the direction of flow Lattice made of hollow profiles becomes visible.

c) Embodiments

Fig. 1:

eine Heizvorrichtung nach dem Stand der Technik,

Fig. 2:

einen Primärabzug, teilweise mit Hohlprofilen nach dem Stand der Technik,

Fig. 3a:

ein erfindungsgemäßes erstes Hohlprofil im Querschnitt,

Fig. 3b:

ein erfindungsgemäßes zweites Hohlprofil im Querschnitt,

Fig. 3c:

ein erfindungsgemäßes drittes Hohlprofil im Querschnitt,

Fig. 3d:

ein viertes Hohlprofil im Querschnitt, (nicht Teil der Erfindung)

Fig. 4:

das Hohlprofil der Figur 3a in Seitenansicht,

Fig. 5:

eine zweiteilige Bauform eines Hohlprofiles, (nicht Teil der Erfindung)

Fig.6a:

einen vollständigen Primärabzug mit Hohlprofilen gemäß der Figur 3, geschnitten in Strömungsrichtung und

Fig. 6b:

den Primärabzug der Figur 6a betrachtet in Strömungsrichtung.

Embodiments according to the invention are described in more detail below by way of example. Show it:

Fig. 1:

a heating device according to the state of the art,

Fig. 2:

a primary fume cupboard, partly with hollow profiles according to the state of the art,

Fig. 3a:

a first hollow profile according to the invention in cross section,

Fig. 3b:

a second hollow profile according to the invention in cross section,

Fig. 3c:

a third hollow profile according to the invention in cross section,

Fig. 3d:

a fourth hollow profile in cross section, (not part of the invention)

Fig. 4:

the hollow profile of the Figure 3a in side view,

Fig. 5:

a two-part design of a hollow profile, (not part of the invention)

Fig. 6a:

a complete primary fume cupboard with hollow profiles according to Figure 3 , cut in the direction of flow and

Fig. 6b:

the primary deduction of the Figure 6a viewed in the direction of flow.

• Dabei wird Brennmaterial, beispielsweise Holzscheite, auf dem Boden eines Brennraumes 20 liegend verbrannt.

the Figure 1 shows a known heating device in the side sectional view:

• In this case, fuel, for example logs, is burned lying on the floor of a combustion chamber 20.

In the front surface of the housing of the combustion chamber 20 there is a combustion chamber flap 22 which can be opened upwards, operated by a manual control 25, which in this case is coupled to a direct exhaust flap 16 in the ceiling of the combustion chamber 20, which is normally closed and only When the combustion chamber flap 22 is opened, the flue gases 14 can then be drawn off directly into the chimney 26 via the ceiling of the combustion chamber 20.

In the normal case, however, i.e. with the combustion chamber flap 22 closed, the flue gases 14 pull from the combustion chamber 20 through a primary exhaust 1 horizontally, preferably to the rear, into the afterburning chamber 21 and are thereby supplied with additional combustion air or via a recirculation path 15 from the combustion chamber 20 or over Recirculation openings 23 from the afterburning space 21 are mixed with recirculated flue gas in order to optimize the afterburning.

This takes place in that the primary vent 1 consists in this case of horizontally extending hollow profiles 2 arranged one above the other, between which there are clear passages 3 which narrow in the flow direction 10 and act as nozzle slots.

Secondary air is released into these passages 3 via outlet openings 4 in the hollow profiles 2 and thus mixed with the flue gases 14 flowing out of the combustion chamber 20.

The flue gases post-burned in this way in the afterburning space 21 leave the heating device in the direction of the chimney 26, the chimney effect being able to be regulated by a regulating flap 18 arranged at the end of the afterburning space 21.

In the afterburning chamber 21, the rear wall is also designed as a heat exchanger 27 through which liquid flows, but this is irrelevant for the present invention.

• Figur 2 zeigt eine Schnittdarstellung durch einen Teil eines Primärabzuges 1 bestehend aus beispielhaft drei nebeneinander angeordneten Hohlprofilen 2, deren Querschnitt in dieser bekannten Bauform (die rechten beiden Hohlprofile 2) etwa A-förmig ist, so dass sich die Durchlässe 3 dazwischen in Strömungsrichtung 10 verjüngen und als Düsenschlitze wirken.

The subject of the invention is the primary fume cupboard 1 consisting of hollow profiles 2 arranged one above the other or next to one another, which is shown in full or in part in the following figures:

• Figure 2 shows a sectional view through part of a primary flue 1 consisting of, for example, three hollow profiles 2 arranged next to one another, the cross-section of which in this known design (the two hollow profiles 2 on the right) is approximately A-shaped, so that the passages 3 between them taper in the flow direction 10 and as Nozzle slots work.

In this case, the hollow profiles 2 consist of a V-shaped sheet metal, which forms a front tip and side walls projecting backward from this in the direction of flow 10, and one that is tightly inserted into the open rear side of this sheet, set back from its free ends, in particular welded back plate 5, which together offer a hollow interior. Secondary air and / or recirculation gas can be supplied via this hollow interior, which is then released via outlet openings 4 in the side walls of the hollow profiles 2 into the passages 3 and thus the flue gas 14 flowing through there.

Because of the overhang over the back plate 5 to the rear, the gas mixture flowing through the nozzle-like passages 3 behind the back plate 5 forms a reversing vortex 19 on each side of the hollow profile 2, whereby a good mixing of the flue gases 14 with the supplied secondary air and / or the recirculation gases is achieved from the hollow profiles 2 and thus leads to an improved afterburning in the afterburning chamber 21.

• Zum einen ist das freie Ende des Überstandes oder Fortsatzes 6 bereits als schneidenförmige, spitz zulaufende Abrisskante 7 ausgebildet.

In Figure 2 the two right hollow profiles 2 shown in the known, A-shaped cross-sectional shape, the left hollow profile 2, on the other hand, already has an improvement according to the invention:

• On the one hand, the free end of the protrusion or extension 6 is already designed as a cutting edge, tapering to a point.

Furthermore, the outer surfaces 2a are spherically shaped from the widest point towards the rear up to the spoiler edge 7, which favor the reversal vortex, and as a result of which the free ends, that is to say the spoiler edges, approach one another.

The back plate is also curved so that it has a concave outer surface, that is to say the rear, even if it should not yet run up to the tear-off edge 7 without kinks.

The tear-off edges 7 are formed at an acute angle by sharpening the area of these free end edges.

• Wie Figur 3a zeigt, ist das Hohlprofil 2 aus einem Stück eines Rundrohres, also eines Rohres 2 mit kreisrundem Querschnitt, und insbesondere gleichbleibender Wandstärk, hergestellt, welches vorzugsweise lediglich - wie in Figur 4 dargestellt - an seinen Enden einen speziellen Zuschnitt erfährt, um in eine umgebende Struktur eingepasst und stirnseitig aufgelegt werden zu können.

the Figures 3 and 4th show a hollow profile 2 that is improved again and that is again simplified in terms of manufacturability:

• As Figure 3a shows, the hollow profile 2 is made from a piece of a round tube, that is, a tube 2 with a circular cross-section, and in particular a constant wall thickness, which is preferably only - as in Figure 4 shown - is given a special cut at its ends so that it can be fitted into a surrounding structure and placed on the face.

It is essential to the invention, however, that in the middle area relevant to the mixing of the flue gases in the direction of extent 2 'of the hollow profiles 2, apart from these specially designed ends, in which a large number of outlet openings 4 for secondary air are also spaced apart in this direction of extent 2' Segment strips 29 were separated from the same tube 2 and welded again into the resulting recess with the previous inside facing outwards, as in the cross-sectional view of FIG Figure 3a evident.

In this tightly welded state - the front openings at the end of the segment strip 29 inserted are tightly closed by a sealing part 32 against the subsequent complete circular cross-section of the pipe 2 - the back plate 5 then has a concave outer surface 5a, the radius of curvature of which corresponds to the radius of curvature of the inside of the pipe .

The tear-off edges 7 resulting from this assembly are usually obtuse-angled, but can be shaped at an acute angle by appropriate processing.

This causes the formation of inverted eddies 19, as in the Figure 2 shown, further improved in that they can be maintained very stably over a long period of time.

The distance 9 in the transverse direction 11 of the two tear-off edges 7 is approximately 70% of the width 28, that is to say the outer diameter, of the hollow profile 2 in this illustration.

The hollow profile 2 is designed symmetrically to the longitudinal center plane 10 ′, which runs centrally and vertically on the segment strip 29.

The outlet openings 4, which are preferably opposite one another with respect to this longitudinal center plane 10 ′, are set back somewhat in the direction of the back plate 5 from the widest point of the tubular profile 2 along the longitudinal center plane.

The design of the hollow profile 2 according to Figure 3b differs from that of the Figure 3a in that the segment strip 29 protrudes beyond its outer circumference at the point of contact with the tube 2, in that it has the same radius of curvature as the tube 2, but is a larger segment angle, i.e. not the segment separated from this tube 2, but from a segment other pipe with preferably the same outer and / or inner diameter and preferably the same wall thickness originates.

The ends of this segment strip 29, viewed in cross section, are acute-angled with an angle at the tip of preferably about 50 ° to 70 °, the outer flank being inclined such that its direction of inclination - viewed in the course of direction 2 '- is a tangent to the Represents the outer circumference of the tube 2, since it has been found that this promotes the formation of reversal eddies particularly well.

The ends of the segment strip 29 preferably do not protrude beyond the widest point of the cross section of the tube 2.

The design of the hollow profile according to Figure 3c differs from that of the Figure 3b in that the segment strip 29 inserted there into the recess of the tube 2 has a smaller radius of curvature, that is to say originates from a tube with a larger outer or inner diameter than the tube 2.

Otherwise, here too, the segment strip 29 with its ends preferably protrudes over the outer circumference of the tube 2 at the contact point and, in contrast to the ends, at Figure 3b - Preferably also over the widest point of the tube 2, that is, its diameter 28, on both sides.

Since also with the design according to Figure 3c the outer flank of the tear-off edge 7 designed as a pointed cutting edge represents a tangent to the outer circumference of the tube 2 in its extension, the angle of the acute-angled cutting edge 7 is smaller here than in the design according to FIG Figure 3b , namely only about 40-50 °.

Figure 3d shows a design in which no segment strip of another, in particular round, pipe is inserted and in particular welded into the recess of the pipe 2, but an angle profile.

Otherwise, the protrusion and the design of the lateral tear-off edges 7 can preferably be analogous to that in FIG Figures 3b and 3c be designed as described.

As Figure 4 As can be seen, one end of the hollow profile 2 is closed at the front, while the end on the left in the figure is partially open at the front and forms an inlet opening 31.

Figure 5 shows a two-part design in cross section, only one part, the front part 2.1, being a hollow profile, in this case in one piece, the rear end of which in turn forms the back plate 5.

Here, too, the hollow profile 2 is again laterally symmetrical to the longitudinal center plane 10 '.

In the right half of the picture, the front part 2.1 is shown with a cross-sectional contour like the closed part of the A-shape in Figure 2 shown in the left half the front part 2.1 is shown approximately semicircular in cross section, each with a flat, that is to say straight, back plate 5.

On both sides of the longitudinal center 10 ', one of the angled control profile parts 8a, b is in each case on the back plate 5, namely on the outer surface of the bend between its two legs 8a1, 8b1, the inclination of which relative to the back plate 5 by means of an adjusting screw 33 and a this leg 8a1, 8b1 can be adjusted away from the back plate 5 with a force-acting disc spring 30.

The adjusting screw 33 preferably extends through both of these legs 8a1, 8b1 and is screwed more or less strongly into a threaded hole in the back plate 5, which lies on the longitudinal center plane 10 '.

The other leg 8a2, 8b2 has a spherically curved outer surface, and at its free end a tear-off edge 7 that tapers to a point in cross-section. 8b2, preferably in such a way that the widest point of the entire profile in the flow direction 10 lies just behind the rear side of the back plate 5, that is to say in the area of the freely tapering legs 8a2, 8b2.

In this way, the distance 9 between the two tear-off edges 7 to one another can be changed depending on the intended use.

Figure 6a shows a primary passage sectioned in the longitudinal direction, the flow direction 10, in which the flow direction 10 of the flue gases 14 runs from bottom to top.

In this primary flue, two rows 34a, b of hollow profiles 2 are arranged one behind the other in the flow direction 10 within the surrounding housing that carries the flue gases 14, the ends of which are in receiving bodies rest, via which the supply of the secondary air flowing out of the hollow profiles 2 also takes place at least on one side, in which case, for example, the one-piece design of the hollow profiles 2 according to FIG Figure 3 is chosen.

Within the two rows 34a, b, the hollow profiles 2 lie parallel at a distance from one another. The direction of the hollow profiles of the one row 34a runs transversely, here at right angles, to the direction of the hollow profiles 2 of the other row 34b, so that viewed in the flow direction 10, as in FIG Figure 6b shown, results in a grid of hollow profiles 2 through which the smoke gases 14 must flow.

REFERENCE LIST

1

Primary deduction

2

Hollow profile

2.1

Front part

2a

Exterior surface

2a1

front area

2a1

the backstage area

2 '

Direction of progress

3

passage

4th

Outlet opening

5

Backplate

5a

Outer contour

6.6 '

Appendix

7th

Tear-off edge

8th

Tax profile

8th'

Contact line

8a, b

Control plate parts

8a1 / 2

leg

8b1 / 2

leg

9

distance

10

Direction of flow

10 '

Longitudinal median plane

11

Transverse direction

12th

Appendix

13th

Recess

14th

Flue gas

15th

Recirculation path

16

Direct exhaust flap

17th

Swivel axis

18th

Regulation flap

19th

Whirlwind

20th

Combustion chamber

21

Afterburning room

22nd

Combustion chamber flap

23

Recirculation opening

24

partition wall

25th

Hand control

26th

chimney

27

Heat exchanger

28

broad

29

Segment strips

30th

Disc spring

31

Inlet opening

32

Sealing part

33

Adjusting screw

34a, b

line

Claims (16)

1. a) Heating device for solid fuels, having a combustion chamber (20) which can be connected via a primary flue (1) to an afterburning chamber (21) in which the smoke gases (14) flowing out of the combustion chamber (20) are afterburned, the primary flue (1) comprising

   b) a plurality of tubular hollow profiles (2) which are arranged at a distance from one another transversely to their direction (2') of extension,

   c) wherein the at least one free passage (3) between the hollow profiles (2) forms at least one nozzle slot for the smoke gases (14) passing through in the direction of flow (10),

   d) the hollow profiles (2) having outlet openings (4) through which the secondary air supplied via the interior of the hollow profiles (2) and/or recirculated smoke gas flows into the passages (3),

   characterized in that

   e) the outer surfaces (2a) of the hollow profile (2), from the broadest point in the direction of flow (10), converge towards the rear, i.e. in their rear region (2a 2), of the longitudinal central plane (10') of the hollow profile (2),

   f) the outer surfaces (2a) of the hollow profile (2) ending in the direction of flow (10) each in a tear-off edge (7), the spacing of which can also be greater than the greatest width of the outer contour of the hollow profile (2), and

   g) a back plate (5) connecting the two tear-off edges (7) and forming the rear part of the hollow profile (2) has a concave outer contour (5a).
2. Heating device according to claim 1,
   characterized in that
   the hollow profiles (2) are formed symmetrically with respect to their longitudinal central plane (10'), which contains the direction of flow (2') of the hollow profile (2).
3. Heating device according to one of the preceding claims,
   characterized in that

   a) viewed in the direction of flow (2') of the hollow profiles (2), the hollow profiles (2) have outer surfaces (2a) which move away from one another in the flow direction (10) of the smoke gases (14) from the front to the rear, at least in the front region (2a 1),
   and/or

   b) the outlet openings (4) are arranged in front of or at the latest at the widest point of the outer contour (2a) of the hollow profile (2) in the direction of flow (10).
4. Heating device according to one of the preceding claims,
   characterized in that

   a) the rear free end of the tear-off edge (7) is designed as a V-shaped edge as viewed in cross-section, in particular as a cutting edge,

   b) in particular with an edge radius, viewed in the direction of extension (2'), of less than 2 mm, preferably of less than 1 mm, preferably of less than 0.5 mm, preferably of less than 0.3 mm, preferably of less than 0.2 mm, and/or

   c) the tear-off edge (7) is formed as an acute-angled cutting edge, the cutting angle of which is smaller than 85°, better smaller than 80°, better smaller than 75°, better smaller than 60°, better smaller than 50°.
5. Heating device according to one of the preceding claims,
   characterized in that

   a) the rear side (5a) of the back plate (5) merges into the tear-off edge (7) formed as a cutting edge without a shoulder and without a kink with a kink radius which is smaller than 6 mm, better 4 mm, better 2 mm,
   and/or

   b) the rear side (5a) of the back plate (5) has a concave curvature whose radius of curvature is in particular between 0.5 cm and 5 cm, better between 0.8 cm and 4 cm, better between 1.0 cm and 3 cm, better between 1.3 cm and 2.5 cm, better between 1.4 cm and 2.0 cm.
6. Heating device according to any one of the preceding claims,
   characterized in that
   the rear side (5a) of the back plate (5) has a concave curvature whose radius of curvature

   a) in particular deviates not more than 40%, preferably not more than 30%, preferably not more than 20%, from the average radius of curvature of the outer contour of the cross-section of the hollow profile, in the case of a tubular section with a circular cross-section deviates from the radius of curvature of the outer circumference of this tubular section

   and/or

   b) in the case of a pipe profile with a circular ring-shaped cross-section, the radius of curvature of the concave curvature deviates from the radius of curvature of the outer contour of the pipe profile by not more than 20%, preferably not more than 10%, preferably not more than 5%.
7. Heating device according to any of the preceding claims,
   characterized in that
   the hollow profile (2) has an inlet opening (31) for secondary air, in particular in one of its end faces.
8. Heating device according to one of the preceding claims,
   characterized in that

   a) the outer surfaces (2a) of the rear region (2a2) of the hollow profile (2), viewed in the direction of extension (2'), are flat or convexly curved, and/or

   b) the distance (9) between the two tear-off edges (7) of a hollow profile (2) is between 30% and 60%, preferably between 35% and 55%, preferably between 40% and 50%, of the largest width (28) of the outer contour (2a) of the hollow profile (2) in the transverse direction (11), in particular of the outer diameter (28) of the hollow profile (2) designed as a round tube (2).
9. Heating device according to any one of the preceding claims, characterized in that

   a) the hollow profile (2) is a tube (2) with a round cross-section, from which a segment strip (29) extending in the direction of extension (2')

   b) is tightly fastened, in particular welded, to the rest of the tube (2) with its previous tube inner side facing outward.
10. Heating device according to one of the preceding claims, characterized in that

    a) the hollow profile (2) is a tube (2) with a round cross-section, with a recess extending in the direction of extension (2'),

    b) in which a strip (29') with a cross-section which is curved as viewed in the direction of flow (2') is tightly fastened, in particular welded, with its concave side,

    c) in particular a segment strip (29') of another pipe with a cross-section, in particular round, and a different diameter, with its previous pipe inner side facing outwards.
11. Heating device according to claim 10,
    characterized in that

    a) the lateral ends of the strip (29') viewed in the direction of extension (2') project transversely beyond the recess and in particular beyond the widest point of the tube (2) viewed in the direction of flow (10), but preferably by no more than 10%, preferably no more than 20%, more preferably no more than 30% of the width of the tube (2) at the widest point,

    and/or

    b) the outer flank of the break-off edge (7), which is formed as an acute-angled cutting edge, viewed in the direction of extension (2'), with its extension represents a tangent to the outer circumference of the hollow profile (2) or deviates from this tangentially in the direction by a maximum of 10 %, better by a maximum of 20 %, better by a maximum of 30 %.
12. Heating device according to one of the preceding claims,
    characterized in that
    the gap between the front and rear end of the segment strip (29) in the direction of extension (2') and the inner circumference of the tube (2) is tightly closed.
13. Heating device according to one of the preceding claims,
    characterized in that
    the hollow profile (2) is formed in two parts with a front part (2.1) closed in cross-section except for the outlet openings (4) and a control section (8) which extends on the rear side of the back plate (5) of the front part (2.1) in the direction of extension (2'), in particular rests thereon, is detachably fastened and has the tear-off edge (7) projecting rearwardly and in particular is adjustable in its distance (9) from the front part (2.1).
14. Heating device according to one of the preceding claims, characterized in that

    a) the control profile (8) is formed in two parts and the two parts (8a, b) of the control profile (8) are angled and abut the rear side of the back plate (5) with the outer surfaces of the one leg (8a1, 8b1) in each case, and the width (28) of the rear end of the control profile (8) and thus of the distance (9) between the two tear-off edges (7) can be adjusted by pivoting about this contact line,

    and/or

    b) an adjustable set screw (33) presses one leg (8a1, 8b1) of each part (8a, b) against the rear side (5a) of the back plate (5), which is pretensioned in the opposite direction by a spring, in particular a disk spring (30)
15. Heating device according to one of the preceding claims,
    characterized in that

    a) the front part (2.1) has air passage openings in its back plate (5),

    and/or

    b) the front part (2.1) has projections (12) which are spaced apart in the longitudinal direction (10) and project rearwardly beyond the back plate (5) and engage in corresponding recesses (13) in the control plate (8) for guiding the latter.
16. Heating device according to one of the preceding claims,
    characterized in that

    a) the primary flue (1) has a plurality of rows (34a, b), lying one behind the other in the direction of flow (10) of hollow profiles (2) running in a disputed manner, in particular parallel to one another, and

    b) in particular the hollow profiles (2) of one row (34a), viewed in the direction of flow (10), run transversely to the hollow profiles (2) of the row (34b) immediately preceding or following in the direction of flow (10).

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