EP0429371B1 - Shell for a boiler for heating with heat-conveying fluid - Google Patents

Abstract

The invention relates to a heat-transfer fluid heating-boiler body, arranged horizontally and encased at least partially by a jacket (3) for circulation of said fluid, which jacket is provided with an outlet (9) for the heated fluid and an inlet (8) for the cooled return fluid, while one of the ends of the body is arranged so as to receive at least one burner (4) and the other end is provided with an exhaust (5) for the combustion gases. The boiler body according to the invention is characterised in that the fluid return inlet has the form of a perforated distribution tube (8) which is arranged in the top part of the fluid jacket (3) and which penetrates the latter via the side opposite the burner (4), extending towards the side of the latter, while the outlet (9) for the heated fluid is provided in the bottom part of the fluid jacket (3). Advantageously, the internal wall (1) of the jacket (3) of closed periphery arranged at a short distance from said wall (1), while between the latter and said envelope there is a volume for a fluid, so as to form a thin sheet of fluid projecting into the jacket (3). <IMAGE>

Description

The invention relates to a body of a heating fluid heating boiler, arranged horizontally and at least partially enveloped by a jacket for circulation of said fluid, generally water.

In a heating boiler fitted with a burner, the combustion gases are more or less saturated with water vapor depending on the excess air in the flame and also depending on the hydrogen content of the fuels used.

This vapor causes the well-known phenomenon of condensation, also known as the dew phenomenon, as soon as the gases thus saturated meet a wall whose temperature is below a certain temperature (around 55 ° C).

To avoid this undesirable phenomenon of particularly corrosive condensation, it suffices to maintain the wall of the exchanger formed by the water jacket, that which is in contact with the combustion gases, at a sufficiently high temperature (for example 60 ° C. ) by acting on the boiler burner. In this case, however, the boiler water temperature is generally much higher than the temperature required for the heating radiator circuit. This results in heat loss and the obligation to provide a mixing system (mixing or thermostatic valve) at the outlet of the device to lower the flow temperature to the radiators by ensuring mixing with part of the return water. .

Other means have also been devised, in particular in the construction of the wall of the exchanger, facing the combustion gases, by arranging there, for example, fins so as to increase the exchange surface on the side of said gases. combustion to ensure a rapid rise in temperature.

A boiler thus equipped makes it possible to envisage eliminating the mixing valve, so that the boiler regulation system can act directly and only on the burner.

However, it generally does not make it possible to remove all the zones where the temperature would be lower than the temperature causing the condensation. It is therefore necessary to imagine other anti-condensation means.

This is why the invention provides a boiler body of the aforementioned type, the fluid circulation jacket being provided with a departure for the heated fluid and with an inlet for the cooled return fluid, while one of the ends of the body is arranged to receive at least one burner and the other end is provided with a discharge of combustion gases as for example in patent EP-A-0 331 141, the boiler body according to the invention being remarkable in that the arrival of the return fluid is in the form of a perforated distribution tube which is arranged in the upper part of the fluid jacket and which plunges thereon from the side opposite to the burner, extending towards the side of the latter, the outlet of the heated fluid being provided in the lower part of the fluid jacket and preferably on the side opposite to the burner, while the inner wall (1) of said fluid jacket (3) is provided on the opposite side to the burner (4) a closed peripheral envelope (13) arranged at a short distance from said wall (1), and that between the latter and said envelope is formed a volume for a fluid, so as to form a thin sheet of fluid projecting in the shirt (3).

In this way, the return water which is the coldest, is thus brought back into the hottest part (which is due to natural convection, in the upper part of the shirt), the advantages provided by the tablecloth. of fluid being explained below.

In addition, the way in which this return is carried out is original (specific tube) for a boiler of the horizontal type.

Advantageously, the distribution tube is rectilinear and arranged over substantially the entire length of the fluid jacket, while it is at least partially closed at its end and has a plurality of orifices distributed over its length.

In addition and preferably, the orifices of the distribution tube are formed in the upper half of the latter, that is to say in the half facing the outer wall of the fluid jacket, for example in pairs.

In this way, not only is a jet avoided towards the inner wall of the jacket to avoid punctually cooling the latter, but the outer wall is cooled at the same time which can only reduce heat loss.

According to one embodiment, the orifices of the distribution tube are closer to the side of the burner to be more numerous. Indeed, it is obviously towards the burner that the thermal load is the greatest.

To allow the evacuation of any sludge or other impurities contained in the return fluid, an orifice is provided towards the end of the distribution tube, and it is arranged so as to open into the lower half of it, it that is to say in the half facing the inner wall of the fluid jacket.

Advantageously in this case, a deflector is provided between the orifice for discharging the impurities and the inner wall of the fluid jacket.

The thin layer of fluid formed in the jacket by the aforementioned peripheral envelope makes it possible to increase the temperature of the exchange wall, in the areas where the thermal loads are the lowest.

Indeed, the temperature of the combustion gases varies significantly between the heat source on the burner side and the exhaust side of the gases, so that it is advantageous to heat the wall of the latter side.

Given the small amount of liquid in the tablecloth, it will rise very quickly in temperature as soon as the burner is started and will ensure an exchange of thermal energy with the liquid in the jacket located outside, by conduction through the envelope and not by convection, the liquids of the jacket and the tablecloth do not mix or little (see below). According to one embodiment, between the inner wall of the fluid jacket and the peripheral envelope, longitudinal partitions are provided to reduce and / or eliminate any convective movement of the fluid which is between said wall and said envelope.

Although the sheet thus formed could be waterproof, it may also be advantageous to fill it at the time of filling the boiler itself, in which case said envelope has at least one filling orifice and at least one degassing orifice. In the case where there are also longitudinal partitions, these then have openings for filling the volume forming the sheet.

In all cases, the interior wall of the fluid jacket can be provided with a heat exchange surface with solid fins on its face facing the very interior of the body, that is to say towards the combustion gases.

• La figure 1 est une coupe longitudinale d'une chaudière équipée d'un corps selon l'invention,
• les figures 2 et 3 sont des coupes partielles selon les lignes respectivement II-II et III-III de la figure 1,
• la figure 4 est une vue en perspective avec arrachement du corps de chaudière selon la figure 1 et
• la figure 5 est une coupe radiale selon V-V de la figure 4.

The invention will be clearly understood on reading the description which follows and which refers to the appended drawings in which:

• FIG. 1 is a longitudinal section of a boiler equipped with a body according to the invention,
• FIGS. 2 and 3 are partial sections along lines respectively II-II and III-III of FIG. 1,
• FIG. 4 is a perspective view with cutaway of the boiler body according to FIG. 1 and
• FIG. 5 is a radial section along VV of FIG. 4.

The drawings show a boiler body 1 in the form of a cylinder of revolution arranged horizontally. The cylinder forming the body 1 is surrounded by a second cylinder 2 coaxial with the first so as to form between them a closed volume which constitutes a jacket 3 in which water (or another heat transfer fluid) circulates.

The body 1 constitutes a combustion chamber and it is intended to receive at one of its ends, here the left end with respect to FIG. 1, a burner 4 while at its other end, an evacuation is provided 5 of the combustion gases.

The body 1 forms the internal wall of the water jacket 3 and the cylinder 2 the external wall while the internal face of the body 1 is provided with an exchange surface with solid fins 6 as well shown in FIGS. 2 to 5.

This fin surface 6 makes it possible to ensure a rapid rise in temperature, the heat then being transmitted by conduction to the water which circulates in the jacket 3.

The body 1 is further provided with a pot 7 (Figure 1) to better channel and laminate the combustion gases between the fins.

The water to be heated, that is to say the water returning from the heating devices (radiators or other), arrives in the water jacket 3 in the upper part of it as shown in the drawings, that is to say in the zone which is by hottest natural convection, while the departure of the heated water is provided in the lower part.

In addition, the arrival of the return water is carried out by means of a tube 8 which plunges into the jacket 3, on the side opposite to the burner 4, while the departure is carried out by a pipe 9 also connected from the side opposite the burner (Figures 1 and 4).

The inlet tube 8 extends from the side opposite the burner towards the latter over the entire length of the jacket 3, its free end being closed as shown in FIG. 1.

The tube 8 also has perforations 10 for distributing water, over substantially its entire length, these being closer to the side of the burner so as to be more numerous on the warmer side (FIGS. 1 and 4) .

The perforations 10 are formed in pairs, as shown in Figures 2 to 5, in the upper half of the tube 8 (Figures 1 to 5) so as to form jets towards the outer wall 2 of the jacket 3 for the reasons already mentioned above.

Towards the end of the tube 8, there is further provided an orifice 11, in the lower half of the latter for the evacuation of any impurities contained in the return water, while under said orifice 11, that is that is to say on the side of the body 1, a deflector 12 is arranged.

On the side of the gas outlet 5, the body 1 constituting the inner wall of the jacket 3 is provided with a closed peripheral envelope 13 (FIGS. 1 and 3 to 5), which is arranged at a short distance from said wall so to form a volume for a fluid, such as water, thereby constituting a thin sheet projecting into the jacket 3 as shown in FIGS. 1 and 4.

In the volume thus created between the envelope 13 of the body 1, are arranged according to one embodiment, longitudinal partitions such as 14a and 14b (Figures 4 and 5), in order to reduce and / or eliminate any convective movement of the water contained in said volume.

According to one embodiment, the envelope 13 is completely closed to constitute a sealed circuit independent of that of the jacket 3.

However, it may be advantageous to fill the sheet at the time of filling the water jacket itself, and in this case, the casing 13 is then provided with at least one filling orifice such as 15a, 15b, 15c (figure 1) in the lower part and less water a degassing orifice such as 16a and 16b in the upper part (Figures 3 and 5). In this case, the longitudinal partitions 14a, 14b have, of course, also openings to allow the circulation of water during filling, such as 17a, 17b (Figures 4 and 5).

The role of the perforations 10 and the function of the envelope 13 have already been well defined. Likewise, the reasons for the shapes and locations chosen for the orifices 10 and the said envelope have already been specified above, all with the main concern of avoiding the harmful effects of the condensation phenomenon as well as possible.

Claims (12)

1. Shell for a boiler for heating with heat-conveying fluid, disposed horizontally and encased at least in part by a jacket (3) for circulation of said fluid, which jacket is provided with an outlet (9) for the heated fluid and an inlet (8) for the cooled return fluid, whereas one of the ends of the shell is arranged to accommodate at least one burner (4) and the other end is provided with a discharge outlet (5) for the combustion gases, which boiler shell is characterised in that the inlet for the return fluid takes the form of a perforated distribution tube (8) which is disposed in the top part of the fluid jacket (3) and runs into it through the opposite side to the burner (4), extending towards the side of the latter, the outlet (9) for the heated fluid being provided in the bottom part of the fluid jacket (3), whereas on the opposite side to the burner (4) the internal wall (1) of said fluid jacket (3) is provided with a closed peripheral casing (13) arranged a short distance from said wall (1), and a space is provided for a fluid between the latter and said casing, so as to form a thin sheet of fluid projecting into the jacket (3).
2. Boiler shell according to claim 1, characterised in that the outlet (9) for the heated fluid is located on the opposite side to the burner (4).
3. Boiler shell according to one of claims 1 and 2, characterised in that the distribution tube (8) is rectilinear and arranged over substantially the entire length of the fluid jacket (3), whereas it is at least partially blocked at its end and comprises a plurality of orifices (10) distributed over its length.
4. Boiler shell according to claim 3, characterised in that the orifices (10) of the distribution tube (8) are arranged in the upper half of the latter, i.e. in the half facing towards the external wall (2) of the fluid jacket (3).
5. Boiler shell according to claim 4, characterised in that the orifices (10) of the distribution tube (8) are arranged in pairs.
6. Boiler shell according to one of claims 4 and 5, characterised in that the orifices (10) of the distribution tube (8) are closer together towards the side of the burner so as to be greater in number.
7. Boiler shell according to one of claims 2 to 6, characterised in that one orifice (11) is provided towards the end of the distribution tube (8) and in that it is arranged so as to debouch in the lower half of the latter, i.e. in the half facing towards the internal wall (1) of the fluid jacket (3) to permit the discharge of any impurities contained in the return fluid.
8. Boiler shell according to claim 7, characterised in that a deflector (12) is provided between the orifice (11) for discharge of the impurities and the internal wall (1) of the fluid jacket (3).
9. Boiler shell according to one of claims 1 to 8, characterised in that longitudinal partitions (14a,14b) are provided between the internal wall (1) of the fluid jacket (3) and the peripheral casing (13) in order to reduce and/or eliminate any fluid convection movement between said wall (1) and said casing (13).
10. Boiler shell according to one of claims 1 to 9, characterised in that the peripheral casing (13) exhibits at least one filling orifice (15a,15b,15c) and at least one venting orifice (16a,16b,).
11. Boiler shell according to the whole of claims 9 and 10, characterised in that the partitions (14a,14b) exhibits openings (17a,17b) for filling the space forming the sheet.
12. Boiler shell according to one of claims 1 to 11, characterised in that the internal wall (1) of the fluid jacket (3) is provided with a heat exchange surface with solid fins (6) on its face facing towards the inside of the shell, i.e. towards the combustion gases.

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