EP0193433A1 - Heating system for a reverse draught fireplace - Google Patents

Abstract

The heating system comprises a heat reclaimer with hot water circulation which comprises a horizontal exchanger (1) and a vertical exchanger (2). The vertical exchanger (2) is constituted by an essentailly parallelepipedal sheet metal vessel (8) which contains vertical pipes (11), the lower part of which communicates with the compartment (6) of the combustion chamber and the upper part of which opens into the fireplace. These vertical pipes (11) have a cross-section in the form of a polygon or of a circle and define between them passages of small thickness, in which the water to be reheated circulates. Used for increasing the thermal efficiency of heat reclaimers for fireplaces and for facilitating the cleaning of these. <IMAGE>

Description

The present invention relates to an open hearth heating installation and reverse draft.

Numerous heating installations of this type are known. Thus, for example, according to French Patent 2,544,468, there is known a reverse-draw heating installation comprising a heat recuperator with circulation of hot water which comprises a horizontal exchanger and a vertical exchanger connected to a cold water inlet and to a hot water outlet. The horizontal exchanger extends under a grid intended to receive the fuel and in a compartment constituting the combustion chamber, the bottom of the latter comprising an ashtray. This combustion chamber opens into a vertical smoke evacuation compartment in which the vertical exchanger is arranged. The upper part of this vertical compartment opens into the chimney itself.

The advantages of this type of heating installation are well known. Indeed, thanks to the reverse draft, the fumes are completely evacuated towards the bottom of the hearth and not upwards as in the case of normal draft installations, so that these fumes are used in an optimal way to exchange their heat with heat exchanger heat exchangers.

Thus, the thermal efficiency of these installations can reach around 70%, while in normal draft installations, this efficiency does not exceed 20 to 30%, since a part of the calories is evacuated by the escaping fumes straight up into the chimney.

The horizontal and vertical heat exchangers generally consist of tubes inside which the water to be heated is circulated.

In the case of the vertical exchanger, these tubes are enclosed in a compartment which is crossed by fumes which exchange their heat with the tubes of this exchanger.

These fumes deposit soot inside this compartment, so that it must be cleaned periodically. For this purpose, it is necessary to be able to dismantle this compartment, which implies a complicated and expensive construction, because of the need to maintain a perfect seal. In addition, the disassembly and reassembly of the vertical exchanger significantly increase the cost of maintaining the installation, which is particularly unfortunate given the excellent performance and the savings that it provides.

The essential object of the present invention is to remedy this drawback by creating an open hearth heating system and reverse draft, the heat recuperator of which has a vertical exchanger which can be easily cleaned without dismantling, while having an excellent heat exchange efficiency. , its construction being, moreover, simple and inexpensive.

According to the invention, the heating installation for an open hearth fireplace and reverse draft, in which the vertical exchanger is constituted by a rectangular sheet metal receptacle, one of the dimensions of which is small compared to the other two, and which comprises at its lower part a water inlet connected to the horizontal exchanger and at its upper part an outlet for hot water, is characterized in that this receptacle contains vertical conduits serving for the passage of smoke, the lower part of which opens into the compartment of the combustion chamber and the upper part of which opens into the chimney proper, these vertical conduits being arranged one beside the other so as to define -between them thin spaces in which the water circulates . These vertical conduits have a section in the form of a polygon or a circle.

These vertical pipes open at the top and bottom, which are used for the passage of smoke, are easily cleaned, without dismantling the exchanger, by introducing a special tool. This special tool can be inserted from above, when the construction of the chimney hood allows, or from below. Preferably, a special tool will be used for this cleaning, introduced from the bottom of the installation, after removal of the ashtray, a tool which will be described in more detail below.

Furthermore, these vertical conduits of the vertical exchanger make it possible to create between them and the side walls of the receptacle, thin passages, in which the water to be heated circulates, these thin passages being favorable for obtaining '' an excellent heat exchange efficiency between the fumes passing through the vertical conduits and this water.

According to an advantageous version of the invention, the vertical conduits are fixed to the side walls of the sheet metal receptacle, by means of metal studs welded to these walls and to these conduits.

These studs constitute a simple and effective means for fixing the conduits to the walls of the receptacle and for imparting sufficient resistance thereto with respect to the pressure exerted by the water. In addition, these pads, preferably made up of discs, do not disturb the circulation of water inside the exchanger.

According to a preferred version of the invention, the horizontal exchanger comprises a series of parallel tubes placed between a cold water collector and a heated water collector arranged perpendicular to the receptacle of the vertical exchanger, the water outlet from the heated water collector being connected to the water inlet located at the bottom of the vertical exchanger receptacle.

The heat recovery unit of the installation according to the invention is thus constituted by the combi original creation of horizontal tubes in which water circulates with vertical conduits of polygon section, crossed by smoke and surrounded by water which communicates with the horizontal tubes.

This original combination allows to obtain simultaneously, a simple construction, having a high thermal efficiency and whose maintenance is easy and inexpensive.

Other features and advantages of the invention will appear in the description below.

• - la figure 1 est une vue en perspective du récupérateur de chaleur d'une installation de chauffage conforme à l'invention,
• - la figure 2 est une vue en coupe suivant le plan II-II de la figure 1,
• - la figure 3 est une vue en coupe suivant le plan III-III de la figure 1,
• - la figure 4 est une vue à échelle agrandie du détail A de la figure 3,
• - la figure 5 est une vue en coupe transversale partielle d'une variante de réalisation de l'échangeur vertical,
• - la figure 6 est une vue en perspective du récupérateur de chaleur surmonté par une hotte, l'échangeur horizontal étant bordé latéralement par des parois amovibles de faible hauteur,
• - la figure 7 est une vue en perspective analogue à la figure 6, l'échangeur horizontal étant bordé latéralement par des panneaux amovibles de grande hauteur,
• - la figure 8 est une vue latérale, en coupe de la hotte,
• - la figure 9 est une vue frontale, en coupe, de cette hotte,
• - la figure 10 est une vue de l'outil utilisé pour nettoyer l'échangeur vertical.

In the appended drawings, given by way of nonlimiting examples:

• FIG. 1 is a perspective view of the heat recovery unit of a heating installation according to the invention,
• FIG. 2 is a sectional view along the plane II-II of FIG. 1,
• FIG. 3 is a sectional view along the plane III-III of FIG. 1,
• FIG. 4 is a view on an enlarged scale of detail A of FIG. 3,
• FIG. 5 is a partial cross-section view of an alternative embodiment of the vertical exchanger,
• FIG. 6 is a perspective view of the heat recovery unit surmounted by a hood, the horizontal exchanger being bordered laterally by removable walls of low height,
• FIG. 7 is a perspective view similar to FIG. 6, the horizontal exchanger being bordered laterally by removable panels of great height,
• FIG. 8 is a side view, in section of the hood,
• FIG. 9 is a front view, in section, of this hood,
• - Figure 10 is a view of the tool used to clean the vertical exchanger.

In the embodiment of FIGS. 1 to 3, the heating installation for an open hearth chimney with reverse draft, comprises a heat recuperator with water circulation, which comprises a horizontal exchanger 1 and a vertical exchanger 2 connected to an inlet d cold water 3 and a hot water outlet 4 which is itself connected to a central heating installation not shown.

The horizontal exchanger 1 extends under a grid 5 formed of bars intended to receive the fuel and above a compartment 6 (see FIG. 3) constituting the combustion chamber, the bottom of the latter comprising a removable ashtray 7. This combustion chamber 6 opens into a vertical smoke evacuation compartment in which the vertical exchanger 2 is disposed. The upper part of this vertical compartment opens into the chimney proper.

According to the invention, the vertical exchanger 2 consists of a rectangular sheet metal receptacle 8, one of the dimensions of which is small compared to the other two. The receptacle 8 has at its lower part a water inlet 9 connected to the horizontal exchanger 1 and at its upper part an outlet 10 for hot water.

We see in Figures 1 to 3, that this receptacle; 8 contains vertical conduits 11, the open lower part of which communicates with the combustion chamber compartment 6 and the upper part of which, also open, opens into the chimney proper. These vertical conduits 11 have a square cross section and are arranged in line one next to the other, so as to define between them and with the front and back walls of the receptacle 8, passages 12 of small thickness and of rectangular section ( see figure 2) in which the water to be heated circulates.

As shown in Figures 1, 2, 3 and 4, the vertical conduits 11 are fixed to the side walls of the receptacle 8 made of sheet metal by means of metal studs 13 welded to these walls and to the conduits, thereby ensuring the rigidity necessary for these walls to be able to resist the pressure exerted by water.

These metal studs 13 are constituted by discs each welded to two adjacent conduits II and arranged opposite circular holes 14 (see FIG. 4) of the same diameter formed in the opposite front and back walls of the receptacle 8.

The weld 15 is produced at the edge of these holes 14 and against the discs 13.

As indicated in FIGS. 1 and 2, the receptacle 8 contains, opposite the lower water inlet 9, a vertical tube 16 for the outlet of hot water, the open upper end 10 of which is located near the upper wall 17 of the receptacle, from which projects beyond the end of the vertical conduits 11.

Figures 1 to 3 show on the other hand the horizontal exchanger 1 which comprises a series of parallel tubes 18 placed between a cold water collector 19 and a collector 20 of heated water arranged perpendicular to the receptacle 8 of the vertical exchanger 2. The outlet of the heated water collector 20 is connected to the water inlet 9 located at the bottom of the receptacle 8 of the vertical exchanger 2.

As can be seen in FIG. 3, the tubes 18 each carry a radial fin 21 forming an angle relative to a vertical plane and directed in the direction (see arrows F) of the circulation of the combustion gases.

In the embodiment shown, the two collectors 19 and 20 are constituted by parallelepipedic tanks elongated in sheet metal, fixed on a parallelepipedic compartment 22 also of larger dimensions made of sheet metal, which is open at its upper part and which surrounds the combustion chamber 6 and the ashtray 7.

The vertical exchanger 2 of generally parallelepipedal shape rests and is fixed vertically to the ends of the two parallelepipedic tanks constituting the collectors 19 and 20 of the horizontal exchanger 1. The end of the manifold 20 for leaving the horizontal exchanger 1 comprises at ° its upper part an opening which opens directly into the water inlet opening 9 of the receptacle 8 which constitutes the vertical exchanger.

The cold water inlet manifold 19 has at its end, to which the receptacle 8 is fixed, a compartment 23 (see FIG. 1) separated by a partition 23a from the rest of the manifold 19, into which the vertical tube 16 of hot water outlet, disposed in the receptacle 8. This compartment 23 presents the lateral tube 4 for the outlet of the hot water which is connected to the central heating installation.

It can also be seen in FIGS. 1 to 3 that the two parallelepipedic tanks 19 and 20 constituting the collectors of the horizontal exchanger are joined by bars 5, welded to these tanks, and extending above the tubes 18, these bars 5 forming the grid of the hearth.

Furthermore, the two parallelepipedic tanks 19 and 20 are joined by a front plate 24 welded to the ends of these tanks and extending over the entire height thereof.

Preferably, to improve the draft, the horizontal exchanger 1 is bordered laterally and frontally (see FIG. 6) by removable glass walls (25, 26, 27) which extend over a certain height (10 to 20 cm) above the grid 5. These walls also constitute a stop for the logs which are placed on this grid.

The walls 25, 26, 27 can be replaced by removable walls 28, 29, 30 (see FIG. 7) extending practically to the lower edge 31 of the chimney hood 32. The front wall 29 is advantageously divided into two hinged panels forming access doors to the foyer.

In the embodiments of FIGS. 6 to 9, the hood 32, disposed above the heat recovery unit, comprises a partition 33 extending substantially vertically over part of the height of this hood 32. This partition 33 is disposed substantially parallel to the dorsal face 34 of the hood 32 and separates the latter into two conduits 35, 36, one 35 serving for operation in reverse draft and the other 36 for operation in normal draft (see FIG. 8). This hood 32 further comprises in its upper part a narrowing 37 defining the outlet duct of the hood.

We see in Figures 8 and 9 that the hood 32 includes a single register 38 pivotally mounted at the end 33a of the partition 33, so that it can be moved between a position in which it closes the conduit for normal draft (position shown in solid line in Figure 8) and opens the one used for reverse pulling and a position in which, conversely, it opens the conduit for normal draw and closes the one used for reverse pulling (position in dotted line in the figure 8).

In the first position, the register 38 bears against the base of the narrowing 37 of the hood, while in the second position, the register 38 bears against the dorsal face 34 of the hood.

As indicated in FIG. 9, the register 38 has a very simple rectangular form of embodiment, its lateral edges conforming to the partial vertical profile of the lateral walls of the hood 32. This register 38 therefore allows the intensity of the normal draw and that of the reverse draw to be adjusted as desired.

• Lorsque le registre 38 est dans la position indiquée sur la figure 8, les bûches posées sur la grille 5 du foyer brûlent en formant des flammes et des fumées qui sont dirigées vers le bas. Ces fumées et flammes sont déviées par les ailettes 21 soudées aux tubes 18 dans le sens des flèches F de la figure 3 orientées vers les conduits verticaux 11 de l'échangeur vertical 2. Ces ailettes 21 permettent également d'augmenter la surface d'échange thermique entre la chaleur de combustion et les tubes 18 de l'échangeur horizontal.

The operation of the heating installation which has just been described is as follows:

• When the damper 38 is in the position indicated in FIG. 8, the logs placed on the grate 5 of the hearth burn, forming flames and fumes which are directed downwards. These fumes and flames are deflected by the fins 21 welded to the tubes 18 in the direction of the arrows F in FIG. 3 oriented towards the vertical conduits 11 of the vertical exchanger 2. These fins 21 also make it possible to increase the exchange surface thermal between the combustion heat and the tubes 18 of the horizontal exchanger.

The fumes are evacuated towards the chimney by passing through the vertical conduits 11. These absorb the major part of the calories conveyed by the fumes by yielding them by heat exchange to the water contained in the receptacle 8 which surrounds the conduits 11.

The water heated in the vertical exchanger 2 is collected at the upper end 10 of the tube 16 and then discharged through the outlet 4 located at the bottom of the vertical exchanger 2.

The heat recovery unit of the installation according to the invention is very easy to maintain and clean. The only parts of this recuperator which are liable to become fouled are formed by the interior of the vertical conduits 11. The cleaning of these can be carried out easily, without dismantling, by using the cleaning tool shown in the Figure 10, which is part of the installation according to the invention.

It can be seen in this FIG. 10 that this tool comprises a tube 40 ending in an elbow 41 forming an angle of 90 ° with the tube. A flexible rod 42, for example constituted by a helical spring with contiguous turns, is engaged inside the tube 40, and has at its end a cleaning member 44 such as a hedgehog or a brush of dimensions adapted to the section of the vertical conduits 11 of the vertical exchanger 2.

It is sufficient, after removing the ashtray 7, to introduce the tube 40 into the space located under the tubes 18 of the horizontal exchanger and to engage the cleaning member 44 in each conduit, by sliding the rod 42 inside the tube 40 by actuating the handle 43.

Of course, the invention is not limited to the embodiment which has just been described, and many modifications can be made to it without departing from the scope of the invention.

Thus, the section of the vertical conduits 11 of the vertical exchanger can also be rectangular. This section can moreover be in the shape of any polygon, for example of a hexagon as in the case of the conduits represented in FIG. 5. In this example, the hexagons 11a are arranged one next to the other according to the configuration called in "honeycomb" which makes it possible to obtain the largest exchange surface with the surrounding water for a given volume of the exchanger.

The exchange surface between the vertical conduits 11 and the surrounding water and between these conduits and the fumes passing inside them could be further increased by having fins inside and outside of these ducts.

Likewise, the thermal efficiency of the horizontal exchanger 1 could be further improved by arranging the fins inside the tubes 18, as described for example in French patent application No. 80 15629 filed on July 15, 1980 by the present depositor.

It is also possible to cover the tubes 18 of the horizontal exchanger 1 with a plate of refractory material having orifices. This refractory plate completely isolates the hearth from the heat recovery unit, when the installation operates in normal draft.

Furthermore, the thermal regulation of the installation is advantageously carried out by means of a device comprising a thermal probe in contact with the water circulating in the heat recovery unit, this probe automatically controlling the rotation of the damper 38 around its axis to adjust the draw.

Claims (18)

1. Heating installation for open hearth chimney and reverse draft, comprising a heat recuperator with hot water circulation which comprises a horizontal exchanger (1) and a vertical exchanger (2) connected to a water inlet (3) cold and at a hot water outlet (4), the horizontal exchanger (1) extending under a grid (5) intended to receive the fuel and in a compartment (6) constituting the combustion chamber, the bottom of this comprising an ashtray (7), this combustion chamber opening into a vertical smoke evacuation compartment, in which the vertical exchanger (2) is arranged, the upper part of this vertical compartment opening into the chimney proper , the vertical exchanger (2) being constituted by a substantially parallelepiped receptacle (8), one of the dimensions of which is small compared to the other two, and which comprises at its lower part a water inlet (9) connected to the horizontal exchanger (1) and its part upper outlet (10) for hot water, characterized in that this receptacle (8) contains vertical ducts (11) for the passage of smoke, the lower part of which opens into the compartment (6) of the combustion, and the upper part of which opens into the chimney proper, these vertical conduits (11) being arranged one beside the other so as to define between them spaces (12) of small thickness, in which the water circulates. 2. Installation according to claim 1. characterized in that the side walls of the sheet metal receptacle (8) are connected to the vertical conduits (11) by means of metal studs (13) fixed to the conduits, 3. Installation according to one of claims 1 or 2, characterized in that the vertical conduits (11) have a square or rectangular section and are aligned next to each other so as to leave between them and the side walls of the receptacle, spaces (12) of small thickness and rectangular section. 4. Installation according to claim 1, characterized in that the vertical conduits have a hexagonal section (lla) and are arranged one next to the other in the so-called "honeycomb" configuration. 5. Installation according to one of claims 2 to 4, characterized in that said metal studs (13) consist of discs each welded to two adjacent conduits (11) and arranged opposite circular holes (14) similarly diameter that these discs formed in the opposite side walls of the receptacle (8), a weld (15) being produced at the edge of these holes and against said discs. 6. Installation according to one of claims 1 to 5, characterized in that the receptacle (8) contains opposite to the inlet (9) lower water, a vertical tube (16) outlet of the hot water and whose open upper end (10) is located near the upper wall (17) of the receptacle. 7. Installation in accordance with one. claims 1 to 6, characterized in that the horizontal exchanger (1) comprises a series of parallel tubes (18) placed between a cold water collector (19) and a collector (20) of heated water arranged perpendicular to the receptacle (8) of the vertical exchanger, the water outlet of the heated water collector being connected to the water inlet (9) located at the bottom of the receptacle (8) of the vertical exchanger (2) . 8. Installation according to claim 7, characterized in that the tubes (18) carry radial fins (21) forming an angle with respect to a vertical plane and directed in the direction (F) of the circulation of combustion gases. 9. Installation according to claim 7, characterized in that the two collectors (19, 20) are constituted by parallelepipedic tanks elongated in sheet metal, fixed on a parallelepipedic compartment (22) also in sheet metal, open at its upper part and surrounding the combustion chamber (6) and the ashtray (7). 10. Installation according to one of claims 7 to 9, characterized in that the receptacle (8) of the vertical exchanger rests and is fixed vertically on the ends of the two parallelepipedic tanks constituting the collectors (19, 20) of the horizontal exchanger, in that the outlet manifold (20) of the horizontal exchanger has at its upper part an opening which opens directly into the opening (9) for the water supply to the receptacle (8) which constitutes the vertical exchanger, and in that the end of the collector (19) for cold water inlet comprises at its end on which the receptacle (8) is fixed a compartment (23) separated by a partition (23a) from the rest the manifold, into which the vertical tube (16) for the hot water outlet opens, which is disposed in the receptacle (8), said compartment (23) having a lateral tube (4) for the hot water outlet. 11. Installation according to one of claims 9 or 10, characterized in that the two parallelepiped tanks constituting the collectors (19, 20) are joined by bars (5) extending above the tubular elements (18) and forming the grid. 12. Installation according to one of claims 9 or 10, characterized in that the two rectangular tanks constituting the collectors (19, 20) are joined by a front plate (24) extending opposite the receptacle (8 ) over the entire height of the two tanks. 13. Installation according to one of claims 1 to 12, characterized in that the horizontal exchanger (1) is bordered laterally and frontally by removable walls (25, 26, 27) which extend over a certain height at - above the grid (5). 14. Installation according to claim 13, characterized in that the removable walls (28, 29, 30) extend practically to the lower edge (31) of the chimney hood (32}. 15. Installation according to one of claims 1 to 14, comprising a hood (32) disposed above the heat recovery unit, this hood comprising a partition (33) extending substantially vertically over a part of the hood, and separating the hood into two conduits (35, 36), one used for the operation in reverse draft and the other for the operation in normal draft, this hood comprising in its upper part a narrowing (37) defining the outlet duct of the hood, characterized in that this hood (32) comprises a single register (38) pivotally mounted at the end (33a) of the partition (33) between a position in which it closes the duct (36) used for the draft normal and opens, the conduit (35) serving for the reverse pulling and a position in which, conversely, it opens the conduit serving for the normal drawing and closes the one serving for the reverse pulling. 16. Installation according to one of claims 1 to 15, comprising a tool for cleaning the interior of the vertical conduits (11) of the vertical exchanger (2), characterized in that this tool comprises a tube (40) intended to be introduced into the space located under the combustion chamber (6), this tube (40) ending in a bend (41) forming an angle of 90 ° with the tube, a flexible rod (42) being engaged at the inside said tube, this rod (42) having at its end a member (44) for cleaning, of dimensions adapted to the section of the vertical conduits (11). 17. Installation according to one of claims 1 to 16, characterized in that a plate of refractory material having orifices covers the tubes (18) of the horizontal exchanger (1. 18. Installation according to one of claims 15 to 17, comprising a thermal regulation device, characterized in that this device comprises a temperature probe in contact with the water circulating in the recuperator, this probe controlling the rotation of the damper (38) around its axis.

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