EP0429380A1 - Boiler for central heating and/or hot water production and central heating installation hot central heating and sanitary hot water production using this boiler - Google Patents

Abstract

The boiler (1) consists of a double-shell heating body (2) defining at least a first volume (3), in which a heat-transfer fluid circulates, and a second, internal volume, known as a combustion chamber (4), which is equipped with a burner (5) capable of rasing the temperature of said heat-transfer fluid. Moreover, the combustion chamber (4) is surmounted by a tubular exchanger (6) which is also passed through by said heat-transfer fluid. According to the invention, the boiler comprises means for increasing the heat exchange in the combustion chamber (4), which is capable of creating a large natural draught and a very high smoke column at high temperature, and moreover for increasing the heat exchange in said exchanger (6) which is capable of creating pre-established losses of head as a function of the gain in exchange in the region of the combustion chamber and of the draught necessary for good combustion. <IMAGE>

Description

The invention relates to a central heating boiler and / or domestic hot water production as well as a central heating installation and domestic hot water production using said boiler.

In terms of heating domestic or industrial premises, the so-called central heating technique is commonly used, the installations mainly comprising a main boiler, a network of transmitters, such as in particular radiators, and / or a distribution circuit for hot water.

The boiler is intended to raise the temperature of a heat transfer fluid which is then directed to the network of transmitters. This fluid is generally water. In some cases, the boiler is also used to raise the temperature of water intended for sanitary use. This water circulates in a circuit internal to the boiler which allows a separation to be made between the domestic water and the heat transfer fluid.

It is known of such boilers using solid, liquid or gaseous fuels. However, the latter is often preferred because it is easy to implement, efficient and its cost price is advantageous compared to other fuels.

Thus, there are known central heating boilers and / or domestic hot water production, using gas as fuel, consisting of a double jacket heating body, defining at least a first volume in which circulates a heat transfer fluid, such only water, and a second interior volume, called combustion chamber, equipped with a burner, capable of raising the temperature of said heat transfer fluid.

As recalled above, this heat transfer fluid is then directed to a set of transmitters, via a circulation pump, which can be subjected to a regulation set.

Such boilers are very widespread and are generally equipped with a ramp burner placed at the lower part of said combustion chamber. They are generally made to deliver a power of the order of 20 to 25 kW and commonly have a circular shaped heating body.

Also, to match the shape of the combustion chamber, it is necessary to produce a burner consisting of several tubular ramps parallel to each other, arranged in a horizontal plane, the different orifices of each ramp being provided to match the geometry of said chamber.

It should first of all be noted that such an arrangement is on the one hand expensive and on the other hand has a relative efficiency because of the adaptation of the beam of ramps, which defines a rectangular surface, while the body of heats, meanwhile has a circular section.

However, in known boilers, the combustion chamber has a reduced size and it is common to recover only 20% of the heat in the energy production zone. Also, it is mandatory to provide, to avoid waste, energy recovery from the combustion gases generated.

This is why, it is common to have above the combustion chamber a heat exchanger constituted by a volume, capable of containing the heat transfer fluid, crossed by multitudes of smoke tubes, the temperature exchange then taking place at the surface of these tubes. Nowadays, it is common to recover around 80% of the power at this exchanger.

Furthermore, to produce domestic hot water, the boiler comprises a coil, immersed in the heat transfer fluid, the diameter of which corresponds substantially to the outside diameter of the boiler's heating body.

In this case, the domestic hot water being produced instantaneously, that is to say without reserve of accumulation, generally one is not satisfied with heating the domestic water of the coil only by the technique known as of "bain-marie ", through the volume of heat transfer fluid stagnating in the boiler, but on the contrary, the heating body is isolated from the radiator circuit and the circulation of the heat transfer fluid in the heating body is forced to improve the heat exchange.

This is commonly carried out using a three-way valve which allows the heating body to be bypassed in one position, and which also authorizes the circulation of the heat transfer fluid in short circuit by means of the central heating circulation pump. Such an arrangement is generally used to save an additional pump.

Such heating and / or domestic hot water production installations generally give satisfaction to the user. However, it should be noted that the energy consumed is not used to the maximum, which has repercussions on the one hand on the cost price of the installation itself but also in the longer term on the cost of l energy used.

The object of the present invention is to provide a central heating boiler and / or for producing domestic hot water which allows maximum control of the heat exchange between the products of combustion, the heating water, and / or sanitary water.

One of the aims of the present invention is to propose a central heating boiler and / or a production of sanitary hot water having a combustion chamber exploited to the maximum to favor this said heat exchange because, it is there that the the best conditions for a significant heat exchange; indeed it is at this level that we find the strongest differences in temperature between the products of combustion and water.

Another object of the present invention is to provide a central heating boiler, and / or for producing domestic hot water equipped with a burner specially adapted to the shape and dimensions of the combustion chamber to guarantee optimal conditions. combustion and to achieve very high heat exchange coefficients.

Another object of the present invention is to provide a central heating and domestic hot water boiler which is advantageous in terms of its cost price but without this having an impact on its output. In addition, the boiler of the present invention has, with equal external dimensions, if not less, a power comparable to gas boilers generally known.

Another object of the present invention is to provide a central heating and / or domestic hot water production boiler equipped with a cylindrical burner making it possible to advantageously achieve the desired objectives.

Another object of the present invention is to provide a central heating installation and hot water production sanitary, using the boiler of the present invention, which is simplified compared to existing installations, and which makes it possible to save on the said three-way isolation valve used, in known boilers, during the production of 'hot water.

Other objects and advantages of the present invention will appear during the description which follows, which is however only given for information and which is not intended to limit it.

According to the present invention, the central heating boiler and / or, for the production of sanitary hot water, consisting of a double jacket heating body defining at least a first volume in which a heat transfer fluid circulates, and a second interior volume, called combustion chamber, equipped with a burner, capable of raising the temperature of said heat transfer fluid, is characterized by the fact that it includes means for increasing the heat exchange in the combustion chamber, capable of creating a natural draft important and a very high smoke column at high temperature.

Another characteristic of the boiler of the present invention lies in the fact that said combustion chamber is surmounted by a tubular exchanger, through which circulates said heat transfer fluid, equipped with means for increasing the heat exchanger in said exchanger , capable of creating pre-established pressure drops, as a function of the exchange gain at the combustion chamber and the draft necessary for good combustion.

Another important characteristic of the boiler of the present invention lies in the fact that it comprises means for authorizing heating of the domestic water, substantially by direct convection at the level of the combustion chamber, and means for creating a circulation. natural heat transfer fluid at said tubular exchanger, to allow heat exchange between the heat transfer fluid and the domestic water, said heat transfer fluid being stagnant in the boiler.

Finally, the central heating and domestic hot water production system, implementing the boiler of the present invention, is characterized in that it has two separate circuits, one supplying a network of transmitters in fluid coolant, via a circulation pump, the other supplying a domestic hot water distribution circuit, from the cold water network, without the use of a forced circulation pump of the heat transfer fluid contained in the boiler.

• La figure 1 montre une vue en coupe longitudinale d'un mode de réalisation selon la présente invention d'une chaudière de chauffage central et/ou de production d'eau chaude sanitaire.
• La figure 2 montre une coupe de la chaudière représentée à la figure 1 selon l axe II-II.
• figure 3 montre une coupe de la chaudière représentée à la figure 1 selon l'axe III-III.
• La figure 4 montre une coupe partielle de la chaudière représentée à la figure 1 selon l'axe IV-IV, sans les tubes de l'échangeur primaire.
• La figure 5 montre une vue de face d'un turbulateur utilisé dans l'échangeur de chaleur de la chaudière comme cela est représenté à la figure 1.
• La figure 6 montre une vue en coupe selon l'axe VI-VI de la figure 5.
• La figure 7 montre une vue de dessus du turbulateur représenté à la figure 5.
• La figure 8 montre schématiquement une chaudière de chauffage central et de production d'eau chaude sanitaire selon la présente invention et illustre le principe de chauffage de l'eau sanitaire.

The present invention will be better understood on reading the following description accompanied by the accompanying drawings which form an integral part thereof.

• Figure 1 shows a longitudinal sectional view of an embodiment according to the present invention of a central heating boiler and / or domestic hot water production.
• Figure 2 shows a section of the boiler shown in Figure 1 along axis II-II.
• Figure 3 shows a section of the boiler shown in Figure 1 along the axis III-III.
• Figure 4 shows a partial section of the boiler shown in Figure 1 along the axis IV-IV, without the tubes of the primary exchanger.
• FIG. 5 shows a front view of a turbulator used in the heat exchanger of the boiler as shown in FIG. 1.
• FIG. 6 shows a sectional view along the axis VI-VI of FIG. 5.
• FIG. 7 shows a top view of the turbulator shown in FIG. 5.
• Figure 8 schematically shows a central heating boiler and domestic hot water production according to the present invention and illustrates the principle of heating domestic water.

The present invention relates to a central heating boiler and / or domestic hot water production as well as a central heating installation and domestic hot water production.

The present invention provides a high efficiency boiler using gaseous fuels of the natural gas, town gas, butane, propane or similar type.

The present invention has also been particularly developed for producing a domestic wall-mounted boiler whose power is of the order of 20 to 25 kW. However, the provisions structural are not limited in any case to this type of construction and one could consider a boiler that is not wall mounted or even a boiler in lower or higher powers.

The boiler of the present invention has been specially designed to control as much as possible the heat exchange between the products of combustion, the heat transfer fluid, and possibly sanitary water, in the heating body.

In this regard, as shown in Figure 1, the boiler 1 consists mainly of a heating body 2, double jacket, defining at least a first volume 3 in which circulates a heat transfer fluid, such as water for example, as well that a second interior volume, called combustion chamber 4, in which an energy capable of raising the temperature of said heat transfer fluid will be produced, by means of a burner 5.

A first objective which the present invention aims at is to use the fact that at the level of the combustion chamber the best conditions exist for a significant heat exchange, because it is at this location that the differences are found. higher temperature between the products of combustion and the heat transfer fluid.

Unlike known conventional boilers, in which only 20% of energy is recovered in the combustion chamber, according to the present invention, the boiler comprises means for increasing the heat exchange in the combustion chamber 4, capable to create a large natural draft and a column of smoke very high at high temperature.

In other words, according to the present invention, it is sought, at the combustion chamber 4 to have a heat exchange of approximately 40%, the other 60% then being recovered in the rest of the heating body 2 of the boiler.

In this regard, the combustion chamber 4 is surmounted, as is the case with traditional boilers, by a tubular exchanger 6, constituted for example by a set of smoke tubes 7 arranged substantially parallel to the longitudinal axis 8 of the boiler and capable of being traversed by the combustion gases emitted in the combustion chamber 4.

In addition, this tubular heat exchanger 6 defines, at the upper part of the heating body 2, a space interior 9 through which said heat transfer fluid circulates. This space 9 is naturally related to said volume 3 of the lower part of the heating body 2 double jacket in which the heat transfer fluid circulates.

In FIG. 1, the arrows 10 and 11 respectively have simulated on the one hand the inlet of the boiler Ecc or in other words the return network of transmitters and on the other hand, the boiler outlet Scc or in other words the start to transmitters.

In practice, in the embodiment illustrated in FIG. 1, the heating body is formed by two bells 12, 13, in particular made of stainless steel, welded together at their base 14.

The respective ceilings 15, 16 of the two said bells 12, 13 will advantageously consist of sheets, pierced with orifices capable of holding the said smoke tubes 7 vertically.

Figure 3 shows one of the possible smoke tube arrangements. Furthermore, Figures 2 and 4 show the relative arrangement seen from above of the bells forming the heating body.

However, according to the invention, said means for increasing the heat exchange in the combustion chamber 4 are in the form of an increase in the dimensions of said chamber, defining a sheet of enveloping heat transfer fluid 17 at which one seeks to achieve a heat exchange of the order of (0% of the total exchange, where unlike, in known boilers, the exchange was of the order of 20%.

In the embodiment as proposed, for a boiler of 20 to 25 kW, this is obtained by providing a diameter of the combustion chamber in particular of the order of 260 mm and a height of the combustion chamber of around 300 mm by example.

By doing so, we seek to create an increase in natural draft and a very high smoke column at high temperature.

Given this arrangement, and in order to find a space close to that of known conventional boilers, the height of the exchanger 6 and in particular of the smoke tubes 7 must then be reduced.

To offset this decrease, and nevertheless recover the Another 60% 7 of the energy, the boiler of the present invention, and more precisely the tubular exchanger 6, is equipped with means for increasing the heat exchange in the said exchanger, capable of creating pre-established pressure drops depending on the gain in exchange at the combustion chamber, and the draft necessary for good combustion.

Indeed, it is therefore a question of finding the right compromise between the need to keep good combustion yields, and the need to keep good secondary air circulation, that is to say non-polluting combustion hygiene. within the limits of the standard.

According to the invention, said means for aumgenting the heat exchange in the tubular exchanger 6 are in the form of turbulators 18, with significant braking power for the passage of combustion gases in the exchanger 6.

It should be noted that these pressure drops can be envisaged because they are compensated according to the present invention by the said increase in the natural draft of the boiler caused in particular by increasing the height of the combustion chamber.

A particularly advantageous embodiment of such turbulators 18 is illustrated in FIGS. 5 to 7. These are cut stainless steel sheets defining a plurality of fins 19, 20 projecting from the plane of the turbulator as particularly shown in FIG. figure 6.

Depending on the size of the fin 19-20 and its inclination, as well as the spacing pitch "p" between two stages of fins, more or less strong turbulence is produced which slows down the passage of the combustion gases. and which thus allow greater recovery of the temperature for the heat transfer fluid.

To avoid excessive pressure losses, it is nevertheless desired to produce the fins 19-20 alternately, as particularly shown in FIGS. 6 and 7.

Good results have been obtained with rectangular fins of a size close to 20 mm x 8.5 mm spaced 40 mm apart, in cylindrical smoke tubes of the order of 32 mm, substantially over their entire length. .

In addition, in this embodiment, 22 tubes were provided smoke of a height substantially equal to 400 mm arranged in a heating body whose upper part has a diameter close to 260 mm.

Such a configuration leads to the production of a boiler of dimension close to that known with an equivalent or even higher efficiency.

It should be noted in this regard that the efficiency of a boiler depends on the good adaptation between the combustion chamber and the burner. In this regard, the boiler of the present invention can be equipped with either a traditional ramp burner formed by horizontal and parallel tubes arranged at the lower part of the combustion chamber, or by a cylindrical type burner.

The cylindrical type burner is particularly suitable for obtaining optimal conditions because its cylindrical shape is completely adapted to the cylindrical shape of the combustion chamber.

Such a cylindrical burner 5 is illustrated in particular in Figure 1 schematically. In particular, the burner 5 consists of a cylindrical envelope 21, delimiting an interior chamber 22 into which the fuel-oxidant gas mixture is introduced by means of a venturi device 23.

The cylindrical casing 21 also has on its lateral face a multitude of orifices 24 to allow the circulation of the mixture from the inside to the outside of the burner. In addition, to promote the distribution of the heat emitted and to reduce the diameter of the combustion chamber, the cylindrical casing 21 will have a significant height relative to its diameter, for the same power.

The production of such a burner, which will advantageously be placed in the lower part of the combustion chamber, requires compliance with two imperatives, namely good supply of primary air, good supply of additional secondary air.

Regarding the primary air intake, the burner used allows an admission at least equal to 80% of the oxidizing gas, strictly necessary for the production of neutral combustion gases, this is allowed by a large dimensioning of the venturi device. 23.

This first arrangement also facilitates a good supply of additional secondary air necessary, despite the significant height of the burner.

Indeed, thanks to this very good mixture introduced into the interior of the burner, it is only necessary to have secondary air of the order of 40%, which is quite possible by providing the arrangement orifices 24 in vertical ramps, parallel to each other, and spaced regularly enough to form an intake channel between the consequent flames.

In an advantageous embodiment of the present invention, the diameter of the burner chamber is between 130 and 150 mm, the ramps being spaced apart by a pitch between 30 and 50 mm, and having a total passage area between 30 and cm². In addition, the height of said envelope is at least equal to 70 mm, which allows good distribution of the flame over the entire surface of the envelope.

In a particular embodiment of the burner, and by way of example, good results have been obtained for a combustion chamber 4 with an internal diameter of 260 mm, with the following characteristics:
- diameter of the burner chamber 21 substantially equal to 141 mm,
- height of the burner chamber 21 substantially equal to 166 mm,
large diameter of the inlet neck of the venturi 23 substantially equal to 76 mm,
- small diameter of the venturi inlet neck substantially equal to 45 mm,
- height of the venturi inlet neck substantially equal to 34 mm,
- total length of the venturi tube substantially equal to 257 mm,
- space between the ceiling of the burner 5 and the venturi outlet orifice substantially equal to 40 mm,
- pitch between each ramp substantially equal to 42 mm,
- height of each ramp substantially equal to 142 mm,
- width of each ramp substantially equal to 11 mm,
- total passage section of the 11 ramps substantially equal to 3.92.10³ mm².

Such a burner cooperates with the combustion chamber to increase the natural draft and obtain a very high smoke column at high temperature, thanks to its dimensions.

However, in the case where the boiler of the present invention is intended for central heating and for the production of domestic hot water, it advantageously comprises means for authorizing heating of the domestic water substantially by direct conduction at the level of the combustion chamber and means for creating a natural circulation of the heat transfer fluid at the level of said tubular exchanger 6 to allow a heat exchange between the heat transfer fluid and the domestic water, said heat transfer fluid being stagnant in the boiler.

This is particularly illustrated in Figure 8 which shows the boiler in a schematic representation. We find the heating body 2, the combustion chamber 4, at the lower part of the heating body and the tubular heat exchanger 6, at its upper part.

Domestic hot water circulates in the heating body in the traditional way, that is to say in a coil marked 25 in the lower part of the heating body and 26 in the upper part of the latter. It should be noted that the arrangement of the coil 25-26 is more precisely illustrated in FIGS. 1 to 4.

However, it should be noted that the coil 25-26 for the production of domestic hot water, immersed in the heat transfer fluid contained in the boiler, is wound at least on two different diameters.

The first diameter corresponds substantially to the diameter of the combustion chamber 4 and constitutes the coil marked 25 wound all around this combustion chamber.

At the exchanger 6, the upper part 26 of the coil has a smaller diameter than that of the lower part, so that the smoke tubes 7 of the exchanger 6 are arranged on either side of the coil 26 to create around from the surfaces of the latter a natural circulation flow of said fluid stagnating at this level.

The winding on the two diameters is particularly illustrated in FIG. 1 in which we can see the upper part 26 of the coil wound around a central group of seven smoke tubes 7, an outer ring of fifteen smoke tubes 7 then wrapping around the coil 26.

To complete this arrangement and to facilitate the creation of the so-called natural circulation of the stagnant heat transfer fluid in the boiler, the entry Eecs 27 of cold sanitary water is provided at the top of said exchanger 6 and the dry outlet 28 of water domestic hot water at the lower part of the combustion chamber 4.

During the operation of the burner 5, at the combustion chamber 4, there is a direct convection almost between the flame and the coil 25. The space defined between the two bells 12 and 13 filled with coolant 17 stagnant n ' is subject to no traffic given the reduced dimensions of the passage interstices.

On the other hand, at the exchanger 6, two circulation flows are created, illustrated schematically in FIG. 8 by the arrows 29 and 30. This circulation descends inside the coil 26 and rises outside.

The creation of such a circulation is necessary for good heat exchange between the heat transfer fluid and the water to be heated, which makes it possible to avoid the use of a forced circulation of the water contained in the heating body.

Indeed, remember in traditional boilers, we are forced to use a three-way valve which allows bypassing the central heating circuit when drawing hot water. This three-way valve also allows the circulation of the water contained in the heating body in a short circuit.

Thanks to the arrangement of the coil according to the present invention, these traditional arrangements are no longer necessary.

Thus, according to the present invention, the central heating installation and the production of sanitary hot water, implementing the said boiler, has two separate circuits, the first supplying the network of radiators with heat transfer fluid, via a circulation pump. 31. The other separate circuit supplies the domestic hot water distribution pipes, from the cold water network, without using a forced circulation pump of the heat transfer fluid contained in the boiler.

Such a structure allows a substantial saving of a three-way valve which has natural repercussions. on the cost price of the boiler.

To resume the embodiment of the aforementioned boiler, it should be noted that good results have been obtained by providing an average diameter of the coil substantially equal to 290 mm at the combustion chamber and an average diameter of approximately 142 mm around the heat exchanger tubes for a coil section of the order of 16 x 18 mm for example.

It should be noted that the structural arrangements of the boiler of the present invention make it possible to make a gain of approximately 30% in the heating water capacity compared to the boilers of 20 to 25 kW known. Indeed, while known boilers use a volume of about 25 liters of water as a heat transfer fluid, the present invention allows a reduced amount of about 16 liters.

As the water content is lower, it heats faster and the boiler has less thermal inertia and a higher overall operating efficiency.

Likewise, the water content being lower and the tubular exchanger smaller, weight gain of material is obtained, which makes it possible to arrive at a total boiler weight lower than that of known boilers.

Naturally, other implementations of the present invention, within the reach of those skilled in the art, could have been envisaged without departing from the scope thereof.

Claims (9)

1. Boiler (1) for central heating and / or for producing domestic hot water, consisting of a heating body (2) double jacket defining at least a first volume (3) in which circulates a heat transfer fluid and a second internal volume, called combustion chamber (4), equipped with a burner, capable of raising the temperature of said heat transfer fluid, characterized in that it includes means for increasing the heat exchange in the combustion chamber (4 ), able to create a large natural draft and a very high smoke column at high temperature. 2. Central heating boiler and / or domestic hot water production, according to claim 1, characterized in that said combustion chamber (4) is surmounted by a tubular exchanger (6), through which circulates the said heat transfer fluid, equipped with means for increasing the heat exchange in the said exchanger (6), capable of creating pre-established pressure losses as a function of the exchange gain at the combustion chamber (4) and the draft necessary for proper combustion. 3. Central heating and domestic hot water boiler, according to claim 2, characterized in that means for authorizing heating of the domestic water substantially by direct conduction at the combustion chamber (4) and means for creating a natural circulation of heat transfer fluid at said tubular exchanger (6) to allow a heat exchange between the heat transfer fluid (9) and the domestic water, said heat transfer fluid being stagnant in the boiler. 4. Boiler according to claim 3, characterized in that to facilitate the creation of said natural circulation of the stagnant heat transfer fluid in the boiler, there is provided the inlet (27) of cold sanitary water at the top of said exchanger tubular (6) and the outlet (28) of domestic hot water at the lower part of the combustion chamber (4). 5. Boiler according to claim 1, characterized in that it comprises a burner (5) for gaseous fuel, consisting of a cylindrical envelope (21) delimiting an interior chamber (22), in which the fuel-oxidant gas mixture is introduced via a venturi device (23), and pierced a multitude of orifices (24) laterally, having a significant height relative to its diameter, for the same power, favoring the distribution of the heat emitted. 6. Boiler according to claim 1, characterized in that the said means for increasing the heat exchange in the combustion chamber (4) are in the form of an increase in the dimensions of the chamber (4) defining a blade of enveloping heat transfer fluid (17) at which the heat exchange is of the order of 40% of the total exchange. 7. Boiler according to claim 2, characterized in that the said means for increasing the heat exchange in the tubular exchanger (6) are in the form of turbulators (18) with significant braking power for the passage of gases from combustion in the exchanger, these pressure drops being compensated by the said increase in natural draft. 8. Boiler according to claim 3, characterized in that it comprises a coil (25, 26) for the production of domestic hot water, immersed in the heat transfer fluid (3, 17, 9) contained in the boiler, wound at least on two different diameters, one (25) corresponding substantially to the diameter of the combustion chamber (4), the other (26) of a smaller diameter, at the exchanger (6), so that the smoke tubes (7) of the exchanger are arranged on either side of the coil (26) to create around the surfaces of the latter a flow (29, 30) of natural circulation of said stagnant fluid in the exchanger . 9. Installation of central heating and domestic hot water production, using the boiler (1) according to claim 3, characterized in that it comprises two separate circuits, one (10, 11) supplying a network of heat transfer fluid transmitters via a circulation pump (31), the other (27, 28) supplying a domestic hot water distribution circuit, from the cold water network, without the use of a circulation pump forced heat transfer fluid contained in the boiler, during the production of domestic hot water.

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