EP3108180B1 - Solid-fuel combustion chamber - Google Patents

Description

Object of the invention

The present invention relates to a solid fuel fireplace having a stepped burner.

Technological background and state of the art

The combustion of solid fuels has the specificity that it decomposes in two stages. A first phase takes place at the level of the fuel bed which, when heated to high temperature, decomposes into combustible gas, on the one hand, and solid carbon, on the other hand. This same solid carbon is consumed in the presence of oxygen which makes it possible to maintain the fuel bed at a high temperature and to maintain the pyrolysis phenomenon. Once released, the pyrolysis gases can also be burned. To do this, it is necessary that they are brought into the presence of oxygen, mixed with it and brought to a high temperature for a period of time sufficient for the combustion to be complete.

In order to optimize the combustion and to minimize the emissions of gaseous pollutants, it is necessary to stagger the air distribution in order to control the amount put in contact with the fuel in these different phases.

Thus, the document EP 0 401 205 B1 discloses a boiler with a primary combustion chamber, a secondary combustion chamber and respective primary air and secondary air transmission devices. In this document, the secondary air supply device has the configuration of a double-walled cone frustum, the inner envelope being pierced with holes allowing the distribution of secondary air inside the truncated cone crossed by the gases of the primary combustion chamber. This system has the disadvantage that it has been optimized to obtain good combustion at the expense of the aesthetics of the flame. Indeed, the many secondary air supply holes inside the truncated cone will give rise to small unsightly flames in the secondary combustion chamber. However, in certain applications such as fireplaces having a window for viewing the flame, it is not only important to optimize the combustion but also to ensure the aesthetics of the flame. When choosing a fireplace, the consumer will be particularly sensitive to the color (ideally yellow-orange), the size (the largest possible compared to the combustion chamber) and the vigor (ideally calm and dancing) of it.

Of the document JP S55 155110 A an oxidation device is known which is mounted on a combustion chamber to remove carbon monoxide. In this device, secondary air is introduced into a passage around a conical body in which the combustion gases circulate. Due to the upward movement of the combustion gases and the secondary air, the latter are mixed above the conical body before coming into contact with a catalyst layer. The document JP S55 155110 A forms the basis for the two-part form of claim 1.

Document is known US 4,945,837 A a pellet feed system of a fireplace. This system has a fin to direct the fuel to the combustion plate in the upper position and includes ventilation tubes to prevent ignition and combustion of fuel stored in bins. The fin prevents the fuel particles from falling back into the auger and being ground into smaller particles.

Goals of the invention

The present invention aims to achieve a fireplace whose arrangement of the various components of the burner provides an optimized combustion while ensuring the aesthetic qualities of the flame.

Brief description of the figures

• La figure 1 représente une vue en coupe du brûleur au sein du foyer.
• Les figures 2 et 3 représentent une vue du dessus des plateaux brûleurs. A la figure 2, les ouvertures pratiquées dans le plateau pour l'introduction d'air primaire se présentent sous forme d'orifices circulaires alors qu'à la figure 3, elles se présentent sous forme de rainures.
• La figure 4 représente en coupe un zoom sur l'agencement du premier corps creux et du second corps creux accueillants les gaz de pyrolyse issus de la combustion primaire. Les flux d'air primaire, d'air secondaire ainsi que les gaz de pyrolyse sont schématiquement représentés par des flèches. Dans cet exemple comparatif, l'extrémité supérieure du premier corps creux est lisse et ce dernier ne comporte pas de disque. La figure 5 représente ce même agencement avec l'extrémité supérieure du premier corps creux présentant une découpe sous forme sinusoïdale selon l'invention.
• La figure 6 représente sous deux angles différents le premier corps creux muni d'une découpe de forme sinusoïdale à son extrémité supérieure. Les figures 7 et 8 représentent également sous deux angles différents le premier corps creux avec une découpe en forme de créneaux et une découpe en dents de scie respectivement.
• La figure 9 représente en coupe un zoom sur l'agencement du premier corps creux et du second corps creux accueillants les gaz de pyrolyse issus de la combustion primaire. Dans cette variante, comparé à la figure 4, l'extrémité supérieure du premier corps creux est de forme sinusoïdale et un disque est positionné à l'intérieur du premier corps creux.
• La figure 10 illustre à l'aide d'une simulation l'injection tangentielle d'air secondaire dans le conduit formé par la paroi du premier corps creux d'une part, et par la paroi du second corps creux d'autre part, ainsi que l'effet de mélange par recirculation des gaz de pyrolyse au-dessus du disque disposé à l'intérieur du premier corps creux.
• La figure 11 représente une vue du dessus des ailettes de guidage disposées dans le conduit d'air secondaire. La figure 12 représente les mêmes ailettes dans une vue en coupe.
• La figure 13 représente une vue du dessus des ailettes de guidage disposées à l'intérieur du premier corps creux autour du disque. La figure 14 représente les mêmes ailettes dans une vue en coupe avec dans cette variante également des ailettes à l'intérieur du conduit d'air secondaire.
• La figure 15 représente une vue en coupe du brûleur au sein du foyer selon un mode de réalisation de l'invention avec une variante du système d'allumage.
• La figure 16 représente une vue du dessus du plateau brûleur avec un système de décendrage en position fermée. La figure 17 représente une même vue avec le système de décendrage en position ouverte. A la figure 18, le mécanisme de décendrage selon l'invention est représenté à l'aide d'une vue en coupe du brûleur au sein du foyer.

The Figures 1 to 4 are examples not covered by the claims useful for understanding the invention.

• The figure 1 represents a sectional view of the burner within the fireplace.
• The figures 2 and 3 represent a top view of the burners trays. To the figure 2 , the openings in the tray for the introduction of primary air are in the form of circular orifices while at the figure 3 they are in the form of grooves.
• The figure 4 represents in section a zoom on the arrangement of the first hollow body and the second hollow body hosting the pyrolysis gases from the primary combustion. The flows of primary air, secondary air and pyrolysis gases are schematically represented by arrows. In this comparative example, the upper end of the first hollow body is smooth and the latter has no disc. The figure 5 represents the same arrangement with the upper end of the first hollow body having a sinusoidal cut according to the invention.
• The figure 6 represents at two different angles the first hollow body provided with a sinusoidal cut at its upper end. The Figures 7 and 8 also represent from two different angles the first hollow body with a crenellated cut and a sawtooth cut respectively.
• The figure 9 represents in section a zoom on the arrangement of the first hollow body and the second hollow body hosting the pyrolysis gases from the primary combustion. In this variant, compared to the figure 4 , the upper end of the first hollow body is sinusoidal and a disk is positioned inside the first hollow body.
• The figure 10 illustrates by means of a simulation the tangential injection of secondary air in the duct formed by the wall of the first hollow body on the one hand, and by the wall of the second hollow body on the other hand, as well as the mixing effect by recirculating the pyrolysis gases above the disc disposed within the first hollow body.
• The figure 11 represents a view from above of the guide vanes disposed in the secondary air duct. The figure 12 represents the same fins in a sectional view.
• The figure 13 is a top view of the guide vanes disposed within the first hollow body around the disk. The figure 14 represents the same fins in a sectional view with in this variant also fins inside the secondary air duct.
• The figure 15 represents a sectional view of the burner within the fireplace according to one embodiment of the invention with a variant of the ignition system.
• The figure 16 represents a top view of the burner plate with a deashing system in the closed position. The figure 17 represents the same view with the ash removal system in the open position. To the figure 18 , the ash removal mechanism according to the invention is represented by means of a sectional view of the burner within the hearth.

Legend

(1)

Burner tray

(2)

Feed screw

(3)

Spark plug or ignition system

(4)

First hollow body

(5)

Opening in the burner tray

(6)

Primary air supply

(7)

Second hollow body

(8)

Secondary air supply duct

(9)

Disruptive element, also called obstacle

(10)

Guide fin

(11)

Ashtray

(12)

Pyrolysis gas

(13)

Heating element

(14)

Scabbard

(15)

Orifice

(16)

pipe

(17)

Volume supplied with outside air

(18)

Burner tray bottom grid

(19)

Top grid of burner tray

(20)

Vertical rod for actuating the upper grid

(21)

Horizontal actuating rod, secured to the vertical rod

(22)

Openwork part in grids for ash removal

Main characteristic elements of the invention

The terms "lower", "upper", "above" and "below" will be used later, which are to be considered relatively with respect to the upward movement of air or combustion gases. The expression "of substantially complementary shape" will also be used to designate walls that are parallel or almost parallel to one another as shown, for example, in FIG. figure 4 in the overlap area where the first hollow body is attached to the interior of the second hollow body.

• un premier corps creux destiné à accueillir dans son volume intérieur les gaz issus de la combustion primaire, ledit premier corps creux comportant une partie conique ou étant entièrement de forme conique, et
• un conduit d'amenée d'air secondaire disposé autour dudit premier corps creux et débouchant à son extrémité supérieure, ledit conduit étant délimité, d'une part, par le premier corps creux et, d'autre part, par une paroi de forme sensiblement complémentaire à celle du premier corps creux afin d'assurer une injection parallèle de l'air secondaire le long du premier corps creux, caractérisé en ce que
• l'extrémité supérieure du premier corps creux où débouche le conduit d'amenée d'air secondaire présente une découpe sous forme d'une succession de saillies et de creux.

The present invention relates to a solid fuel fireplace comprising a stepped burner with a lower stage where, in use, a primary combustion of the solid fuel takes place and with an upper stage where, in use, a secondary combustion of the gases from of the primary combustion, said burner comprising on the upper floor:

• a first hollow body intended to receive in its interior volume the gases resulting from the primary combustion, said first hollow body having a conical portion or being entirely of conical shape, and
• a secondary air supply duct disposed around said first hollow body and opening at its upper end, said duct being delimited, on the one hand, by the first hollow body and, on the other hand, by a substantially shaped wall; complementary to that of the first hollow body to ensure a parallel injection of the secondary air along the first hollow body, characterized in that
• the upper end of the first hollow body which opens the secondary air supply duct has a cut in the form of a succession of projections and recesses.

• le premier corps creux est surmonté d'un second corps creux ;
• le premier corps creux est partiellement rapporté à l'intérieur du second corps creux dans une zone dite de recouvrement, le second corps creux faisant office de paroi délimitant le conduit d'amenée d'air dans la zone de recouvrement ;
• dans la zone de recouvrement, le premier corps creux et le second corps creux sont respectivement de forme convergente dans la direction de déplacement des gaz ;
• dans la zone de recouvrement, le premier corps creux et le second corps creux sont respectivement de forme divergente dans la direction de déplacement des gaz ;
• le second corps creux est de forme divergente en sortie de l'étage supérieur afin d'élargir et ralentir l'écoulement des gaz de pyrolyse ;
• l'extrémité supérieure du premier corps creux comporte une partie conique convergente ou divergente ou une partie cylindrique surmontant la partie conique inférieure ;
• l'extrémité supérieure du premier corps creux où débouche le conduit d'amenée d'air secondaire présente une découpe en dents de scie, une découpe de forme sinusoïdale ou une découpe en forme de créneaux ;
• le premier corps creux et/ou le second corps creux comportent dans leur volume intérieur un élément perturbateur assurant une recirculation des gaz au-dessus dudit élément perturbateur ;
• il comporte des ailettes de guidage obliques disposées dans le conduit d'amenée d'air secondaire et/ou dans le volume intérieur du premier corps creux afin d'induire respectivement un mouvement circulaire à l'air secondaire et au gaz de pyrolyse ;
• les ailettes de guidage sont positionnées autour de l'élément perturbateur ;
• les ailettes de guidage sont disposées à un angle compris entre 15 et 45° ;
• l'étage inférieur du brûleur comporte un plateau et une vis sans fin permettant l'alimentation en combustible solide sur ledit plateau ;
• le plateau comporte des ouvertures permettant l'introduction d'air primaire ;
• le plateau est configuré pour que les cendres générées par la combustion primaire tombent par débordement du plateau ;
• le plateau comporte deux grilles superposées comportant chacune des parties ajourées de forme complémentaire, une première grille en position supérieure étant montée mobile en rotation par rapport à une seconde grille en position inférieure, ledit foyer comportant un mécanisme d'actionnement assurant la rotation de la grille supérieure pour permettre la mise en vis-à-vis des parties ajourées de chaque grille et ainsi l'évacuation des cendres ;
• le mécanisme d'actionnement comporte une tige verticale solidaire de la première grille et une tige horizontale montée mobile et solidaire de la tige verticale, le déplacement de la tige horizontale entrainant la mise en rotation de la première grille ;
• il comporte un système d'allumage, ledit système comportant un fourreau métallique muni d'un orifice, un élément chauffant inséré dans ledit fourreau métallique, un volume intérieur au foyer connecté à l'orifice et destiné à être alimenté en air extérieur qui est, en utilisation, chauffé par l'élément chauffant avant d'être injecté au sein de l'étage inférieur du brûleur.

According to particular embodiments of the invention, the focus comprises at least one or a suitable combination of the following characteristics:

• the first hollow body is surmounted by a second hollow body;
• the first hollow body is partially attached to the inside of the second hollow body in a so-called overlap area, the second hollow body acting as a wall delimiting the air supply duct in the covering zone;
• in the overlap zone, the first hollow body and the second hollow body are respectively convergent in the direction of movement of the gases;
• in the overlap zone, the first hollow body and the second hollow body are respectively of divergent shape in the direction of movement of the gases;
• the second hollow body is of divergent shape at the outlet of the upper stage in order to widen and slow down the flow of the pyrolysis gases;
• the upper end of the first hollow body has a conical or divergent conical portion or a cylindrical portion overlying the lower conical portion;
• the upper end of the first hollow body which opens the secondary air supply duct has a sawtooth cut, a sinusoidal cut or a crenellated cutout;
• the first hollow body and / or the second hollow body comprise in their internal volume a disturbing element ensuring a recirculation of the gases above said disturbing element;
• it comprises oblique guide vanes disposed in the secondary air supply duct and / or in the interior volume of the first hollow body in order to respectively induce a circular movement to the secondary air and to the pyrolysis gas;
• the guide vanes are positioned around the disturbing element;
• the guide vanes are arranged at an angle of between 15 and 45 °;
• the lower stage of the burner comprises a plate and a worm allowing the supply of solid fuel on said plate;
• the plate has openings allowing the introduction of primary air;
• the tray is configured so that the ashes generated by the primary combustion fall overflowing the tray;
• the plate comprises two superimposed grids each having perforated portions of complementary shape, a first grid in the upper position being rotatably mounted relative to a second grid in the lower position, said hearth comprising an actuating mechanism ensuring the rotation of the grid upper to allow the setting in vis-à-vis the perforated parts of each grid and thus the evacuation of ashes;
• the actuating mechanism comprises a vertical rod secured to the first grid and a horizontal rod movably mounted and secured to the vertical rod, the displacement of the horizontal rod causing the rotation of the first grid;
• it comprises an ignition system, said system comprising a metal sleeve provided with an orifice, a heating element inserted into said metal sleeve, an interior volume at the focal point connected to the orifice and intended to be supplied with outside air which is, in use, heated by the heating element before being injected into the lower stage of the burner.

Detailed description of the invention

The present invention relates to a stove-type fireplace or solid fuel insert such as pellets, coal, biofuels, etc.

The fireplace according to the invention comprises a stepped burner, that is to say a burner with a two-stage combustion.

The burner shown in figure 1 comprises in its lower part a plate 1 on which the fuel is fed by means of a feed screw 2. Above the burner plate 1 is positioned a spark plug 3 which, during the phase of ignition, blows hot air at very high temperature on the fuel and leads to the ignition of the latter. The very high temperature present in the volume between the burner plate 1 and the first hollow body 4 will lead to the decomposition of the fuel pyrolysis gas and solid carbon (pyrolysis phenomenon).

Burner plate 1 is provided with openings 5 in the form of circular holes or grooves, allowing the introduction of primary air 6 which feeds the combustion of solid carbon from pyrolysis (see figures 2 , 3 , 4 and 5 ).

Once produced, the pyrolysis gases 12 penetrate into the first hollow body 4 and then into a second hollow body 7 (see FIG. figures 4 and 5 ). The first hollow body 4 has a conical portion or is conically shaped and the second hollow body 7 has one or more conical portions. As illustrated in figures 4 and 5 the first hollow body 4 has a conically shaped portion converging in the direction of movement of the pyrolysis gases and the second hollow body 7 comprises two conical parts successively convergent and divergent in the direction of movement of the gases leading to a depression at the limit of the convergent and divergent zones by venturi effect. The secondary air is injected parallel along the first hollow body 4 in an oblique conduit 8 opening on the upper end of the first hollow body 4 (see figures 1 , 4 and 5 ). In this configuration, the secondary air is preheated by contact with the hot walls of the first hollow body.

Preferably, the upper part of the first hollow body 4 is attached inside the second hollow body 7 so that the pipe 8 is formed, on the one hand, by the outer wall of the first hollow body 4 and, d on the other hand, by the inner wall of the second hollow body 7. In order to ensure the parallel injection of the secondary air, which will also be called tangential injection, the second hollow body comprises in its lower part a substantially shaped portion. complementary to that of the first hollow body. Thus, the first convergent hollow body is attached to the interior of the converging lower portion of the second hollow body.

As illustrated in figures 4 and 5 , the inner wall of the second hollow body 7 comprises the aforementioned convergent and divergent portions joined by a substantially cylindrical zone. This succession of convergent, cylindrical and divergent portions may be composed of a combination of conical volumes or be of toric form. As mentioned above, the convergent portion delimits the duct 8 to ensure a tangential injection of secondary air. As for the divergent portion, it leads to an enlargement and a slowing of the flow at the outlet of the burner. This makes it possible to increase the time of presence of the gases in a hot zone in order to ensure their complete combustion and to obtain a wide and calm flame which optimizes their aesthetic character. According to a variant of the invention (not shown), the second hollow body may be entirely of divergent shape in the direction of movement of the gases. In this case, the first hollow body is also divergent in the direction of movement of the gas to ensure the tangential injection.

According to the invention and as already explained, the first hollow body 4 comprises a conical portion which delimits the air supply duct and allows its tangential injection. The upper end of this first hollow body 4 may have a particular cutting that optimizes the mixing between the secondary air and the pyrolysis gases. The cut is in the form of a succession of hollows and ridges. For example, the upper end of the first hollow body 4 may have a sinusoidal shape shown in FIGS. Figures 5, 6 and 9 . Alternatively, it may be in the form of sawtooth or crenellations (see respectively the Figures 8 and 7 ). The upper end is either convergent in shape in continuity with the conical portion as shown in FIG. figure 9 or may present as illustrated in Figures 6 to 8 a diverging cylindrical or conical portion (not shown). In other words, the first hollow body has a conical portion surmounted at its upper end of a conical or divergent conical portion or a cylindrical portion. According to the invention, the three types of cutting apply regardless of the shape of the upper end (conical or cylindrical).

Optionally, a disturbing element 9 visible among others to figures 1 and 9 can be mounted inside the first hollow body 4. It can be in the form of disk, ring, star, etc. and serves to promote the recirculation of the pyrolysis gases above the disturbing element as simulated at the figure 10 (the disruptive element in the form of a disk being schematized by a white space). It can be mounted inside the first hollow body as illustrated in the figures but also inside the second hollow body with the same function to promote the mixing of gases.

Still with a view to optimizing the mixture, oblique guide vanes with an angle of between 15 ° and 45 ° may be arranged at the level of the secondary air channel 8, as shown inter alia to Figures 11 and 12 and / or between the interfering element 9 and the inner wall of the first hollow body 4 as shown inter alia to Figures 13 and 14 . They can be added in order to induce a circular movement to the flow and thus promote the mixing of the gases and widen the flame at the burner outlet.

Regarding the ignition system, it may according to one embodiment of the invention be composed of a heating element 13 inserted into a metal sleeve 14 closed by a wall at its upper end and by the heating element at its lower end (see figure 15 ). An orifice 15 formed in the lower part of the sheath and a conduit 16 connected to the upper part of the sleeve allow a flow of air from the volume 17 supplied with outside air. In contact with the heating element 13, the air is heated and is injected at the level of the burner plate 1. The fact of taking the air in the volume 17 and not in the room makes it possible to optimize the tightness of the apparatus.

Finally, it will be specified that the ashes generated by the combustion fall from the burner tray 1 by overflow and that the device may comprise a mechanism making it possible to facilitate the evacuation of the ash from the burner tray 1 towards the ashtray 11.

According to an alternative presented to Figures 16 to 18 , the burner plate 1 comprises two grids 18,19 superimposed each provided with openings 5 for the primary air inlet and perforated portions 22 of complementary shape. The grid in the lower position 18 is stationary while the grid in the upper position 19 is rotatably mounted around the center of the burner plate. Under the effect of an actuating mechanism described below, the perforated portions 22 of the upper grid are brought vis-à-vis the perforated portions 22 of the lower grid to ensure the evacuation of ash. The upper grid 19 is actuated by means of the vertical rod 20 which is integral with the horizontal rod 21, the front-to-rear actuation of the horizontal rod ensuring the rotation of the upper grid with respect to the lower grid. It will be specified that the present invention also covers the variant where the actuation is provided by a motor.

Advantages of the invention

The absence of lateral orifices in the first hollow body and the control of the flow conditions at the outlet of the burner thanks to the diverging zone of the second hollow body make it possible to obtain a large calm and dancing flame of orange color.

The injection in a direction parallel to the wall of the first hollow body ensures a progressive contacting of the gases from the primary combustion with the secondary air and therefore a progressive combustion of the pyrolysis gases. This makes it possible to obtain a long flame as well as a relatively calm flow downstream of the secondary air injector. On the other hand, the parallel injection induces a driving effect of the primary flow, i.e. pyrolysis gases, by the secondary flow, which allows to model the flame according to the orientation of the secondary injection.

The particular cut of the first hollow body allows, on the one hand, to create turbulence at the places of contact between the gases from the primary combustion with the secondary air. This promotes mixing at the reaction zone and provides complete combustion. It allows, on the other hand, to obtain a passage section of the gases from the primary combustion leading to a quiet flow while guiding the gas to allow the modeling of the flame.

By optimizing the reaction conditions between the pyrolysis gases and oxygen, the combustion efficiency is improved and the emission of polluting gases is reduced.

There is no flame disturbance and slag generation induced by falling pellets as observed in supply systems using a top spout.

The aesthetics of the burner are optimized thanks to its shape and the absence of visible mechanical elements in the combustion chamber.

Claims (15)

1. A solid-fuel furnace comprising a staged burner with a lower stage where, during use, a primary combustion of the solid fuel takes place and with an upper stage where, during use, a secondary combustion of the gases (12) from the primary combustion takes place, said burner comprising on the upper stage:

   - a first hollow body (4) intended to accommodate, in its inner volume, the gases (12) from the primary combustion, said first hollow body (4) comprising a conical part, and

   - a secondary air supply duct (8) arranged around said first hollow body (4) and emerging at its upper end, said duct (8) being delimited, on the one hand, by the first hollow body (4) and, on the other hand, by a wall with a shape that is substantially complementary to that of the first hollow body (4) in order to guarantee a parallel injection of secondary air along the first hollow body (4),

   characterized in that the upper end of the first hollow body (4) into which the secondary air supply duct (8) emerges has a cutout in the form of a series of protrusions and hollows.
2. The furnace according to claim 1, comprising a second hollow body (7), the first hollow body (4) being topped by said second hollow body (7).
3. The furnace according to claim 2, wherein the first hollow body (4) is partially attached to the inside of the second hollow body (7) in a so-called overlap zone, the second hollow body (7) serving as wall delimiting the air supply duct (8) into the overlap zone.
4. The furnace according to claim 3, wherein, in the overlap zone, the first hollow body (4) and the second hollow body (7) respectively have a convergent shape in the movement direction of the gases (12).
5. The furnace according to claim 3, wherein, in the overlap zone, the first hollow body (4) and the second hollow body (7) respectively have a divergent shape in the movement direction of the gases (12).
6. The furnace according to any one of claims 2 to 5, wherein the second hollow body (7) has a divergent shape at the outlet of the upper stage so as to widen and slow the flow of the pyrolysis gases (12).
7. The furnace according to any one of the preceding claims, wherein the upper end of the first hollow body (4) comprises a convergent or divergent conical part or a cylindrical part.
8. The furnace according to any one of the preceding claims, wherein the upper end of the first hollow body (4) into which the secondary air supply duct (8) emerges has a sinusoidal cutout, a sawtooth-shaped cutout or a crenel-shaped cutout.
9. The furnace according to any one of the preceding claims, wherein the first hollow body (4) and/or the second hollow body (7) comprise, in their inner volume, a disruptive element (9) ensuring a recirculation of the gases (12) above said disruptive element (9).
10. The furnace according to claim 9, comprising oblique guiding fins (10) arranged in the secondary air supply duct (8) and/or in the inner volume of the first hollow body (4) so as to cause a circular movement of the secondary air and the gas (12) respectively, the guiding fins (10) being positioned around the disruptive element (9).
11. The furnace according to any one of the preceding claims, wherein the lower stage of the burner comprises a plate (1) and a worm screw (2) allowing the supply of solid fuel on said plate (1), said plate (1) comprising openings (5) allowing the introduction of primary air (6).
12. The furnace according to claim 11, wherein the plate (1) is configured so that the ashes generated by the primary combustion fall by overflow from the plate (1).
13. The furnace according to claim 11 or 12, wherein the plate (1) comprises two superimposed grates (18, 19) each comprising openwork parts (22) having a complementary shape, a first grate in the upper position (19) being rotatably mounted relative to a second grate in the lower position (18), said furnace comprising an actuating mechanism (20, 21) ensuring the rotation of the upper grate (19) to allow the openwork parts (22) of each grate (18, 19) to be placed opposite one another and thereby making it possible to discharge the ashes.
14. The furnace according to claim 13, wherein the actuating mechanism comprises a vertical rod (20) secured to the first grate (19) and a horizontal rod (21) movably mounted and secured to the vertical rod (20), the movement of the horizontal rod (21) driving the rotation of the first grate (19).
15. The furnace according to any one of the preceding claims, comprising an ignition system, said system comprising a metal sheath (14) provided with an orifice (15), a heating element (13) inserted into said metal sheath (14), a volume (17) located inside the furnace connected to the orifice (15) and intended to be supplied with outside air that is, during use, heated by the heating element (13) before being injected within the lower stage of the burner.

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