EP0102911A2 - Device and method for heat recovery in a fire-box - Google Patents

Abstract

The invention relates to a heat recovery device in an open fire. According to the invention, the drain is replaced by a recuperator essentially consisting of heat exchange tubes (3) embedded in a heat accumulator material from which the calories are subsequently extracted. A production method is also claimed. Application: recovery of calories for home use.

Description

The present invention relates to a device for recovering calories in an open or closed fire, device of the type in which the fumes and exhaust gases pass through heat exchange tubes.

The invention also relates to a method for producing such a device.

Several systems have been proposed for several years allowing the recovery of calories in open fireplaces and, more recently, in closed fireplaces.

The common denominator of all these devices is to have tubes of all kinds in the passage of smoke and exhaust gas from the batteries, the heat exchange surfaces being more or less optimized from one device to another. In the same way, the shapes and relative positions of the tubes were varied to satiety.

The yields obtained by these devices remain however still low and the heating is not regular.

The object of the present invention is to overcome these drawbacks.

According to the invention, this result is obtained with a device of the type described above, characterized in that it replaces the flue of the chimney and in that the heat exchange tubes are embedded in a material forming an accumulator heat.

It will be understood that the accumulation produced in the accumulator material produces a thermal buffer, which allows better regularity of heating.

The accumulator material may be of any known type compatible with the intended application, for example a refractory concrete or any other material using a binder. It can also be composite.

Advantageously, the device will be produced directly on site from a metal drain. box and comprising vertical or inclined organ tubes on the horizontal and in this case converging towards the center of the drain, the accumulator material being poured directly into the box around the exchanger tubes.

According to another embodiment of this method, the tubes will be replaced by reservations made in the accumulator material when it is poured, the reservations being withdrawn later after drying of the refractory material.

Thanks to this device, the refractory mass is heated by the passage of smoke in the tubes. With this structure, a considerable and well distributed exchange surface is obtained, since as many tubes can be placed as desired.

This set allows several hours of heating after extinguishing the fireplace thanks to the accumulation. The accumulated heat can be statically rejected or forced by turbine. The rejection takes place for example by upper orifices or more advantageously by a multitude of pipes passing through the refractory material and emerging in the upper part on a collector connected to the outside of the device.

• - un circuit de tubes traversés par les fumées et reliés à un collecteur de fumées lui-même relié à la cheminée,
• - un circuit de canalisations dans lesquelles circule un fluide à réchauffer, par exemple de l'air, qui se réchauffe par extraction des calories accumulées, ce circuit débouchant sur un collecteur relié vers l'extérieur au réseau d'utilisation.

In this embodiment, two circuits are therefore produced:

• - a circuit of tubes traversed by the smoke and connected to a smoke collector itself connected to the chimney,
• - A circuit of pipes in which circulates a fluid to be heated, for example air, which heats up by extraction of the accumulated calories, this circuit leading to a collector connected towards the outside to the network of use.

Advantageously, the air will circulate in the pipes by natural convection.

The recuperator of the invention can be placed for example on a very thick hearth made of refractory concrete designed on the same principle, that is to say in which the legs have air circulation pipes, or even very advantageously on a closed hearth.

The hearth is generally provided with peripheral air circulation ducts, the circulation operating by natural convection, which allows a first recovery of calories on the refractory side walls of the hearth before the air reaches the level of the device of l 'invention.

It is also possible to combine in a single unit the closed hearth and the metal drain box into which the refractory material will be poured. The installation of such a device becomes easy, quick and accessible to the individual.

• - excellente répartition de la chaleur dans le matériau réfractaire grâce à l'avaloir perforé sur toute sa surface de base par les tubes échangeurs ;
• - grande puissance de chauffe avec une bonne régulation du fait du tampon réalisé grâce à l'accumulation ;
• - amélioration du tirage du foyer grâce à l'aspiration provoquée par la masse de matériau réfractaire chauffe ;
• - entretien et ramonage des tubes échangeurs possible et aisé ;
• - dans le cas spécifique d'un foyer fermé, on évite le noircissement de la vitre grâce à une combustion parfaite sans bistrage, les fumées étant aspirées par les tubes au droit de la vitre ;
• - du fait de la masse de béton sur l'ensemble du foyer, le rayonnement dans la pièce est amélioré ;
• - de manière générale, grande économie de combustible (bois) à performances égales ;
• - enfin le dispositif est très fiable, car il n'y a pas de pièce mécanique complexe ou de tubulure spéciale, donc pas de risque de détérioration.

The advantages of the device according to the invention are also the following:

• - excellent distribution of heat in the refractory material thanks to the drain perforated over its entire base surface by the exchanger tubes;
• - high heating power with good regulation due to the buffer produced by the accumulation;
• - improvement of the draft of the hearth thanks to the aspi ration caused by the mass of heated refractory material;
• - maintenance and sweeping of the exchanger tubes possible and easy;
• - in the specific case of a closed hearth, the blackening of the glass is avoided thanks to perfect combustion without bistrage, the fumes being sucked in by the tubes in line with the glass;
• - due to the mass of concrete on the whole hearth, the radiation in the room is improved;
• - in general, great fuel economy (wood) with equal performance;
• - Finally, the device is very reliable, since there is no complex mechanical part or special tubing, therefore no risk of deterioration.

• - la figure 1 est une vue perspective en coupe partielle d'une cheminée à foyer ouvert équipée du dispositif récupérateur conforme à l'invention ;
• - la figure 2 est une vue en coupe selon II-II de la figure 1 ;
• - la figure 3 est une vue en coupe transversale partielle d'un foyer fermé adapté pour un dispositif récupérateur conforme à l'invention.

The invention will be better understood with the aid of the description below of a non-limiting mode of implementation given by way of example, with reference to the appended drawings in which:

• - Figure 1 is a partial sectional perspective view of an open fireplace equipped with the recovery device according to the invention;
• - Figure 2 is a sectional view along II-II of Figure 1;
• - Figure 3 is a partial cross-sectional view of a closed hearth adapted for a recovery device according to the invention.

On a fireplace with an open or closed hearth, generally referenced (1), there is a device generally referenced (2) and in accordance with the invention.

• - des tubes (3) verticaux ou inclinés par rapport à la verticale et dans ce cas convergents,
• - un collecteur de fumées (4) de forme sensiblement cylindrique et dans lequel débouchent les tubes (3) soit directement soit par le biais d'une chambre collectrice intermédiaire non représentée.

This device includes:

• - tubes (3) vertical or inclined relative to the vertical and in this case convergent,
• - a smoke collector (4) of substantially cylindrical shape and into which the tubes (3) open either directly or through an inter collecting chamber medium not shown.

The tubes (3) are preferably distributed in organs or batteries over the entire volume of the device (2).

According to the invention, the tubes (3) are embedded in a refractory material (5), for example refractory concrete.

The tubes may be metal tubes integral with the box (6) of the recuperator (2), or be formed during the pouring of the refractory material by providing in it reservations, for example with expanded polystyrene or any other similar material which may be removed after setting of the concrete.

A part of the reservation elements can even be left in place, these being consumed from the first fire to release the tubes. It will suffice that at least one of the tubes is released before starting the fireplace for the draft.

This embodiment is the simplest mode of implementation of the device of the invention and its manufacturing process.

Advantageously, the calories accumulated in the refractory mass will be extracted by a fluid circulation, preferably from the ambient air circulating by natural convection.

The air will pass through the refractory mass (5) having accumulated heat through pipes (7) shown in Figure 2 in rectangular section as opposed to the tubes shown in circular section for better understanding. It is clear that the pipes (7) and the tubes (3) can be of any section, and even of different sections within each of the two families.

The pipes (7) will preferably be arranged over the entire periphery of the refractory mass and will converge at their upper part towards a hot air recovery manifold (8) connected by an orifice (9) to the circuit. of use.

Advantageously, the pipes (7) will extend into the jambs of the chimney, the air being extracted in the lower part of the chimney.

It will be understood that the hot air collector (8) is traversed right through by the smoke collector (3).

Of course the refractory mass can be made from prefabricated stackable elements, but preferably it will be cast on site by the user or the installer, in accordance with the method of the invention.

The invention finds a particularly advantageous application in combination with a closed hearth. In this case the closed hearth and the box can form an assembly which is placed as such in a chimney, after pouring the refractory.

Lateral air circulation around the closed hearth can be achieved by bringing on the side walls of the hearth a crenellation (10) as shown in Figure 3, the hollow tubes (11) of this crenellation being connected directly to the circulation tubes air (7). Of course the tubes (11) are open at their lower part. The gaps between the tubes (11) are filled with concrete or other material.

In the case of an open hearth, the air supply to the hearth will be carried out in the traditional way. In the case of a closed hearth, this will be carried out in a manner known in itself by a central orifice placed at the bottom of the box, with possibly the possibility of distributing this co-combustion air over the entire surface.

Advantageously, a device for slowing down gases and fumes, of the register type, regulating the outlet flow rate of fumes and gases and especially making it possible to increase the exchange time at the device of the invention will be provided in the flue pipe. .

On the other hand in the case of a closed hearth, the part upper thereof may, instead of being metallic, simply be made of a consumable material on which the accumulator material will be poured. When it has solidified, the consumable part will disappear on first use. This also prevents formwork.

On the other hand it is clear that the accumulator assembly can be prefabricated, for example made of stackable layers.

To optimize the conditions for sweeping the tubes of the device, provision will be made for the tubes (3) to open into a funnel-shaped chamber, only one of the tubes (3) being in the vertical axis and in the center of this chamber. , in direct alignment with the duct (4). So all the soot will essentially fall into one tube.

Finally, provision may be made for a shutter valve which can be operated from the outside and which makes it possible to vary the free opening section of the smoke tubes.

Many other modifications may be made without departing from the scope of the invention. Thus, the pipes can be fixed directly against the walls of the hearth, passing first below the hearth, then against the bottom before coming into the recuperator.

Claims (19)

1. Device for recovering calories in an open or closed fire, device of the type in which the fumes and exhaust gases pass through heat exchange tubes, characterized in that it replaces the flue of the chimney , and in that the heat exchange tubes (3) are embedded in a material forming a heat accumulator. 2. Device according to claim 1, characterized in that the accumulator material is refractory. 3. Device according to claim 2, characterized in that the refractory material is refractory concrete or other material using or not a binder. 4. Device according to any one of claims 1 to 3, characterized in that the tubes (3) are arranged in vertical or inclined and convergent organs, and that they open into a smoke collector (4). 5. Device according to any one of claims 1 to 4, characterized in that the tubes (3) are distributed regularly in the refractory material. 6. Device according to any one of claims 1 to 5, characterized in that it further comprises a network of air circulation pipes (7), these pipes (7) opening into a manifold (8) connected to the air usage network. 7. Device according to claim 6, characterized in that the accumulated calories are evacuated by air circulating in the pipes (7) by natural convection. 8. Device according to any one of claims 1 to 7, characterized in that the calories are removed from the accumulator by a turbine. 9. Device according to any one of claims 1 to 8, characterized in that it is used in combi naison with a closed hearth. 10. Device according to claim 9 for a closed hearth, characterized in that the closed hearth and the box (6) are made in one piece. 11. Device according to claim 10, characterized in that the side walls of the closed hearth are provided with a crenellation (10) comprising tubes (11) for air circulation connected to the pipes (7). 12. Device according to any one of claims 1 to I1, characterized in that it comprises in the flue pipe, a device for slowing down gases and fumes making it possible to increase the duration of exchange at the level of the accumulator. . 13. Device according to any one of claims 1 to 12, characterized in that the tubes (3) open into a funnel-shaped chamber, only one of the tubes (3) being in the vertical axis and at center of said chamber, in direct alignment with the duct (4). 14. A method for manufacturing a heat recovery device according to any one of claims 1 to 13, characterized in that the refractory material is poured in place in the box (6). 15. Method according to claim 14, characterized in that the box (6) comprises tubes (3) which are integral therewith. 16. A method for manufacturing a heat recovery device according to any one of claims 14 and 15, characterized in that the accumulator material is poured onto a plate of consumable material. 17. Method according to any one of claims 14 to 16, characterized in that the tubes are produced by pouring by providing reservations in the refractory material. 18. The method of claim 17, characterized in that a part of the reservation elements remains in the accumulator and is consumed later. 19. A method for manufacturing a heat recovery device according to any one of claims 1 to 13, characterized in that the accumulator assembly is produced by prefabrication in stackable layers.

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