FR2644230A1 - HEATING BALL OF A LIQUID, PARTICULARLY WATER, AND ONE-PIECE COMBUSTION AND HEAT EXCHANGE ASSEMBLY FOR SUCH A BALL - Google Patents

Abstract

The invention relates to a tank for heating a liquid, in particular water, and a one-piece combustion and heat exchange assembly intended to equip such a tank and comprising a front plate 7 provided with removable fixing means on the tank. the wall of the balloon, a combustion chamber 10 secured to this front plate facing an opening 9 formed in the latter, a plurality of tubes 12, each in the general shape of a U, having a short branch 12a fixed to the wall end 11 of the combustion chamber 10, and a long branch 12b fixed to the front plate 7, a burner 8 carried by the front plate 7 facing the opening 9 of the latter, and a manifold 13 carried by this plate facing the ends of the long branches 12b of the tubes 12. According to the invention, this one-piece assembly is introduced into the balloon through an orifice 4 in the form of an ovoid, and the tubes 12 are arranged in a bundle in the form of general of U so that l The long branches 12b are grouped laterally on one side of the combustion chamber 10, and the short branches 12a are grouped at the rear and in alignment with this chamber 10.

Description

HEATING BALL OF A LIQUID, ESPECIALLY WATER,

  AND COMBUSTION AND HEAT EXCHANGE MONOBLOCK ASSEMBLY

INTENDED TO EQUIP SUCH A BALLOON

  The invention relates to a heating cylinder for a liquid, especially water. It extends to a block of combustion and heat exchange intended for b

equip such a balloon.

  Among the various techniques used for the production of domestic hot water or hot water, superheated water and / or steam in the industrial field, a common technique consists in using a heating body comprising a heat exchanger in which circulate them

  combustion gases from a burner.

  As a general rule, installations carried out according to this technique comprise a liquid storage tank provided with an orifice opposite which is mounted a burner, a submerged heat exchanger inside the tank and inside which the fumes circulate. combustion from the burner, and a collector

  of exhaust intended to evacuate the fumes.

  A first embodiment, commonly used at present, thus consists of a cylindrical balloon closed at its two ends by caps at the

  level of each of which is provided a closed bedroom.

  The burner is mounted towards one of the ends of the balloon opposite a long hearth formed in one of the chambers and extending inside the balloon so as to open into the opposite chamber. The heat exchanger consists of a bundle of tubes connecting the two chambers and to which the fumes from the fireplace are channeled in order to circulate a second time in heat exchange with the

  liquid before being discharged to a collector.

  Although the performance of such facilities is significant, due to the round trip imposed on

  smoked, the latter have two major drawbacks.

  On the other hand, the multiplicity of exchange tubes poses mechanical-strength problems because the welded connections of the latter at the end chambers are relatively fragile. In addition and above all, the maintenance of such installations proves to be very delicate or even impossible,

  taking into account the difficulties of access to the various elements.

  To overcome this last drawback, several solutions have been envisaged aiming to produce a one-piece combustion and heat exchange assembly intended to be removably introduced inside the balloon through an orifice formed in the wall of this latest. These monobloc assemblies consist of a front plate capable of being fixed to the wall of the tank and carrying on its external face a burner and a smoke collector and, on its internal face, a heat exchange device intended to be submerged inside the tank and communicating respectively with the burner and the collector. Such assemblies are described in particular in French patent na 88,03528 in the name of the applicant, patent GB 2,052,697 and

US Patent 4,465,024.

  Patents FR 88.03528 and GB 2.052.697 thus describe an assembly in which the heat exchanger consists of a tube extending in the extension of the burner and arranged so as to make several round trips inside the balloon before communicating with the smoke collector. According to patent FR 88.03528, this tube is a single tube in the form of a serpentine with multiple torques. According to GB patent 2,052,697, this tube consists of several parallel sections connected at their ends to partitioned chambers, arranged so as to

  allow the passage of fumes from one tube to another.

  As indicated above, such installations make it possible to solve maintenance problems, the combustion and heat exchange assembly being easily removable and accessible. However, they have several drawbacks. First, the multiplication of the number of return journeys, on several levels, leads to artificially oversize the orifice made in the tank as the thermal requirements increase, because the only possible solution to increase the power of the assembly then consists in lengthening the tube (s) and in increasing its (their) diameter. However, this surdipns-ionnenent leads to a mechanical weakening of the wall of the balloon causing maximum stress along the generatrix of the cylinder. Therefore, the installation is limited in power due to the maximum allowable stresses by the tank. In addition, the increase in the section of this orifice leads to a loss of efficiency of the installation, since this surface constitutes an excellent. thermal bridge. Secondly, and taking into account the length of the exchanger, the speed of circulation of the combustion fumes induces a significant pressure drop which can only be compensated by the presence of an air blower, a large consumer of 'energy. Furthermore, the level of pressure generated causes significant noise at the exhaust. US Patent 4,465,024 describes a set which makes it possible on the one hand to overcome the mentoring problems, and on the other hand the problems relating to the

  length of the exchanger of the above-described installations.

  The exchanger described in this patent comprises a large-diameter combustion chamber secured to the front plate opposite an opening formed in the latter, and a plurality of U-shaped tubes distributed externally on the periphery of the cylindrical wall. of this chamber, and the ends of which are respectively fixed to the rear wall 'of the combustion chamber so as to communicate with the interior of the latter, and on the front plate;' the collector is in turn provided with an annular smoke recovery chamber, communicating with the end of the tubes fixed to the front plate. At the outlet of the combustion chamber, the combustion fumes are therefore distributed in the different tubes I the length of the path traveled by these fumes is therefore considerably reduced compared to the aforementioned installations, without however causing a significant drop in efficiency, and this

  thanks to the multiplicity of tubes.

  However, as before, any increase in thermal requirements requires artificially increasing the diameter of the combustion chamber, and consequently that of the orifice of the tank, with all the problems inherent in this increase. In fact, the number of tubes distributed around the periphery of this combustion chamber cannot be increased indefinitely for a given chamber diameter, in particular for manufacturing problems of the assembly. In addition, it should be noted that the design of this monobloc assembly generates manufacturing difficulties. In fact, the tubes must firstly be joined to the end wall of the combustion chamber (by welding or any other known process). However, it turns out that once this operation has been carried out, the attachment of this plate itself to the combustion chamber constitutes a very delicate operation which is difficult to carry out either from inside the chamber, due to the length. from the latter, or from the outside due

the presence of the tubes.

  The present invention aims to overcome the drawbacks of heating cylinders provided with a one-piece combustion and heat exchange assembly described above, and has the main objective of providing a heating balloon having a removable one-piece assembly including the power limit, for a balloon of identical dimensions,

  is much higher than that of known devices.

  Another objective is to provide a heating balloon whose actual storage capacity is greater than

that of known balloons.

  Another objective is to provide a heating flask provided with a monobloc assembly of easy manufacture and

inexpensive.

  To this end, the invention relates to a heating cylinder for a liquid, in particular water, comprising: - a closed storage tank comprising a wall provided with an orifice, - a monobloc assembly for combustion and exchange of heat capable of being introduced inside the tank, through the orifice of the latter, so as to extend partially inside said tank, said assembly comprising: 40. a facade plate provided with 'a

: 5

  opening and orifices called smoke exhaust, and comprising removable fixing means on the wall of the tank -. a combustion chamber secured to the front plate so that the opening of said plate opens into this chamber, and provided with an end wall opposite to said opening, - a multitubular exchanger comprising a plurality of tubes, each, in general de-U shape, having a branch, called short, secured towards its end on the end wall of the combustion chamber so as to communicate with the interior of said chamber, and a branch, called long , of greater length, secured towards its end on the front plate so as to open into the exhaust ports of the latter, a burner carried on the front plate so as to communicate with the combustion chamber of the opening of said plate, 20. and an exhaust manifold carried by the front plate, opposite the orifices

exhaust of said plate.

  According to the invention, this balloon is characterized in that: -. the orifice of the wall of the storage tank has an oval section whose major axis is substantially horizontal, the exhaust orifices of the front plate are grouped so as to fit inside a section substantially centered on an axis coincident with the major axis of the orifice in the wall of the tank, - the opening and the set of exhaust orifices in the front plate are arranged on the latter so as to a. btre located respectively on either side of the small axis of symmetry of the orifice of the wall of the tank, - the tubes are arranged according to a beam which is inscribed inside a section in the general shape of U transverse dimensions substantially smaller than those of the orifice in the wall of the tank and so that the long branches are grouped laterally on one side of the combustion chamber so as to open into the exhaust orifices of the front plate, and that the short branches are grouped at the rear of the chamber

  combustion in line with it.

  It will be noted, firstly, that such a balloon combines all the advantages of that described in US Patent 4,465,024. Indeed, all the elements of the combustion and heat exchange assembly are secured on a front plate, allowing assembly and disassembly

  of this assembly, particularly with a view to its maintenance.

  In addition, the expansions due to temperature gradients are absorbed not by welds, but by the curvature of the tubes. In addition, each tube generates only a small pressure drop allowing the use of smaller and less energy-consuming turbines, while the noise level at the exhaust is lower. This low pressure drop allows in particular the use of combustible gas

  low pressure, in particular domestic pressure of 20 mbar.

  Finally, the speed of circulation of the fumes makes it possible to reduce the wall temperature of the combustion chamber / exchanger assembly, hence a reduction in the risks of scaling on hot spots because the boiling temperature of water under pressure n is not reached along

of the combustion chamber.

  In addition, the balloon according to the invention makes it possible to combine these advantages with specific advantages resulting from its own design. Indeed, the ovoid shape of the orifice of the tank makes it possible to significantly improve the mechanical resistance of the wall of this tank, at the level of its generatrix, since the minor axis of this orifice is found to be substantially vertical. In addition, the arrangement of the combustion chamber and the heat exchanger tubes gives the heat exchanger a much higher capacity, that is to say an installed power / occupied volume ratio.

to that of known installations.

  As a result, the power limit is brought to a level much higher compared to known tanks, without the reduction in the volume occupied by the heat exchanger generating a reduction in efficiency,

  due to the increase in the capacity of the assembly.

  It should also be noted that such a design, by making it possible to reduce the section of the orifice of: the wall of the tank, leads to a reduction in thermal bridges. Finally, the oval section of the orifice allows de * enager the latter at a level of the tank lower than that of known balloons without affecting the resistance of the latter. Consequently, the volume located above the monobloc assembly is increased as well as the capacity

actual tank storage.

  According to a preferred embodiment, the long branches and the short branches of the tubes are respectively arranged in compact hexagonal pitch. (By hexagonal pitch, we mean defining, according to a classic definition, an arrangement in which the tubes are distributed in equidistant concentric circles, a tube being placed in the center, six tubes on the first level circle, then six

  additional tub # s on each upper level circle).

  This arrangement makes it possible to obtain a compactness, that is to say a ratio number of tubes per surface of the circle inscribing the bundle, optimal, and consequently an optimal capacity of the heat exchanger of the order of

  1.5 times that of known exchangers.

  According to an alternative embodiment, the short branches and the long branches of the tubes can also be arranged in a triangular pitch which constitutes a derivative of the compact hexagonal pitch. The compactness obtained from pet agenement is less than that obtained with the compact hexagonal pitch, but such an arrangement has an advantage at the manufacturing level because it provides an arrangement in which the branches of the tubes are aligned vertically -on parallel rows . Thus, such an arrangement makes it possible to produce a bundle in which the tubes arranged in a same vertical row are of the same type.

  length, and therefore lower the manufacturing cost.

  According to another characteristic of the invention, the combustion chamber has a shape 8 - cylindrical and is closed by an end wall consisting of a circular plate secured by welding and provided with exhaust orifices into which the branches open short tubes. This feature has an advantage

  paramount on the manufacturing level of the monobloc assembly.

  In fact, during this manufacturing, the short branches of the tubes are firstly joined, for example

  expanded and then welded onto the circular plate.

  The next operation then consists in welding this circular plate on an open end face of. the combustion chamber. Finally, lastly, the other end of this chamber is welded to the front plate and the ends of the long branches also joined to this plate, by swaging and welding; It can therefore be seen that when mounting the various elements, the surfaces to be welded are always easily accessible. In addition, double security is ensured during the tube / circular plate and tube / front plate connections, since these tubes are in

  first of all expanded and then welded.

  The invention also extends as an essential means for the production of this heating cylinder to the one-piece combustion and heat exchange assembly.

equipping said balloon.

  Other features, goals and benefits

  of the invention will emerge from the detailed description which

  follows with reference to the accompanying drawings which show a preferred embodiment and an alternative embodiment. On these drawings which are an integral part of the

present description:

  - Figure.l is a perspective view of a heating cylinder according to the invention, the one-piece combustion and heat exchange assembly being in the partially extended position, - Figure 2 is a partial horizontal section , on an enlarged scale, the monobloc assembly being in its operating position, - Figure 3 is a perspective view, on an enlarged scale, of a monobloc assembly according to the invention, - Figure 4 is a longitudinal section through a "horizontal plane AA of this set, FIG. 5 is a cross section thereof through a vertical plane BB, FIG. 6 is a perspective view of a

  second embodiment of a balloon according to the invention.

  The heating cylinder and its combustion and heat exchange assembly shown in FIGS. 1 to 5 is intended particularly for the production of hot water,

  sarntaire, or hot water, superheated water and / or steam.

  As shown in Figures 1 and 2, this heating balFion comprises a thermally insulated tank 1 composed of a cylindrical wall 2 of vertical axis, closed by

  two caps 3 of hemispherical end.

  In the lower part of the cylindrical wall 2 is an orifice 4 of ovoid shape on the internal poortour of which is welded a ferrule 5 h flange 6,

  projecting outside this wall.

  This orifice 4 allows the introduction inside the tank 1 of a combustion and heat exchange assembly, all of the elements of which are secured to a front plate 7 intended to be fixed on the flange 6 of the ferrule 5, This front plate 7 has an ovrede shape combined with that of the flange 6 and is provided, on its periphery, with bores 7a making it possible to fix it in a conventional manner on this flange 6.. Thus fixed, it then has axes of vertical and horizontal symmetry merged with

  those of the ovoid orifice 4 of the tank 1.

  Laterally with respect to its vertical axis of symmetry, and centered on its horizontal axis of symmetry, this plate 7 is pierced with a circular opening 9, opposite which is bolted, on the outside, a monobloc burner 8. This bravery 8 can & be of any type known per se and conventionally connected to fuel and air supply pipes

oxidizer <not shown).

  Laterally with respect to its vertical axis of symmetry and the opposite ect to its opening 9, this front plate 7 is also pierced with orifices

  exhaust 7b grouped and arranged in a triangular pitch.

  The assembly of these exhaust orifices 7b is inscribed inside a section of semicircular shape, the center of which is located on the major horizontal axis of the plate 7, substantially equidistant from the minor vertical axis. , that the

opening 9.

  On the internal side of this front plate 7 is welded a combustion chamber 10 of cylindrical shape arranged so that the opening 9 of said plate opens

in said room.

  The opposite end of this combustion chamber 10 is closed by means of a circular end wall i1l secured by welding. This end wall 11 is itself pierced by a plurality of exhaust orifices lla arranged in a triangular pitch in a symmetrical arrangement relative to the orifices

  exhaust 7b of the front plate 7.

  As shown in FIG. 5, this triangular pitch arrangement of the exhaust orifices 7b of the front plate 7 (and by symmetry of those of the end plate 11) determines several parallel rows and

vertical of superimposed orifices.

  The heat exchanger consists of tubes 12, each in the general shape of a U, having a short branch Z12a extending towards its end inside an exhaust orifice lla of the circular plate 11, and a long branch 12b dudgeonné towards its end inside an exhaust orifice 7b of the front plate. In order to ensure a perfect seal, the ends of these branches are further welded, after expansion, respectively on the internal side of the chamber.

  combustion 10, and on the external side of the front plate 7.

  Like the exhaust orifices 7b, lla of the circular plate 11 and of the front plate 7, the short branches 12a and the long branches 12b of these tubes 12 are each grouped and arranged in a triangular step. The bundle of tubes 12 thus formed fits

-.... 11

  alsia inside a section in the general shape of Ut the long branches l2b being grouped. laterally on one side of the communication chamber. bustain 10 and aligned in the extension of the exhaust orifices 7b of the front plate 7, and the short branches 12a being grouped at the rear of said combustion chamber and aligned in the extension of the exhaust orifices lys of the plate

circular l.

  In addition, this generally U-shaped bundle has a transverse section of dimensions smaller than those of the orifice 4 of the wall 2 of the tank 1, so as to

  allow the introduction and removal of the monobloc assembly.

  Finally, each tube 12 comprises, in continuity with the branches 12a, 12b, a return 12c forming the core of the U. As with the branches, these returns 12c are grouped and

arranged in a triangular step.

  It should be noted that the arrangement of these tubes 12, and consequently that of the exhaust orifices 7b, the of the front plates 7 and circular ll-, as well as the possibility of playing on the distance separating the opening 9 and the exhaust orifices 7b of the front plate 7, make it possible to modify the exchange surface as desired as a function of the power required. Indeed, it is thus possible to modify the length of the returns 12c of the tubes 12, as well as the number of these tubes 12 or the shape of the section

  envelope of the branches of these tubes.

  Finally, the front plate 7 carries an exhaust manifold 13 with a horizontal outlet designed to protect the tubes 12 from possible clogging from the outside, and to which any evacuation pipe is connected known per se (not shown) such as

  large diameter commercial chimney.

  This exhaust manifold 13 is disposed on the front plate 7 opposite the exhaust orifices 7b of the latter so as to collect the

  exhaust fumes circulating in the tubes 12.

  The: FIG. 6 represents an alternative embodiment in which the one-piece combustion and heat exchange assembly equips a heating flask provided with a cylindrical peripheral wall 14 of horizontal axis, closed by two end caps 15. This monobloc assembly, identical to that previously described, is then introduced through a household orifice in the lower part of one of the cealottes

  , the other provisions being strictly identical.

Claims (7)

: CLAIMS: 1 / - Heating tank for a liquid, in particular water, comprising a closed storage tank (1) comprising a wall (2) provided with an orifice (4), - an onobloc combustion unit and heat exchange able to be introduced inside the tank (1), through the orifice (4) of the latter so as to extend partially inside said tank, said assembly comprising: a front plate (7) having an opening (9) and orifices (7b) called smoke exhaust, and comprising removable fixing means on the wall of the tank (1), a chamber combustion (10) secured to the front plate (7) so that the opening (9) of said plate opens into this chamber, and provided with an end wall (11) opposite to said opening, 20. a multitubular exchanger consisting of a plurality of tubes (12), each in the general shape of a U, having a branch (12a), said to be short, secured to its end on the end wall (11) of the combustion chamber so as to communicate with the interior of said chamber, and a branch (12b), called long, of greater length, secured towards its end on the plate front (7) so as to open into the exhaust orifices (7b) of the latter, to a burner (8) carried by the front plate (7) so as to communicate with the combustion chamber (10) through of the opening (9) of said plate, À and an exhaust manifold (13) carried by the front plate (7), facing the exhaust orifices (7b) of said plate, said tank being characterized in what: - the orifice (4) of the wall of the storage tank (1) has an oval section whose major axis is substantially horizontal, - the exhaust orifices (7b) of the front plate (7 ) are grouped so as to b fit within a section substantially centered on an axis coincident with the major axis of the orifice (4) of the wall of the tank (1), - the opening (9) and the set of exhaust orifices (7b) of the front plate (7) are provided on the latter so as to be located respectively on either side of the small axis of symmetry of the orifice (4) of the wall of the tank (1), - the tubes (12) are arranged in a bundle inside a generally U-shaped section of transverse dimensions substantially smaller than those of the orifice (4) of the wall of the tank (1) and so that the long branches (12b) are grouped laterally on one side of the combustion chamber (10) to come out into the exhaust orifices (7b) of the front plate (7), and that the short branches (12a) are grouped at the rear of the combustion chamber (10) in alignment with it.   2 / - Heating cylinder according to claim 1, characterized in that the long branches (12b) and the short branches (12a) of the tubes (12)   are respectively arranged in a compact hexagonal pitch.   3 / - Heating cylinder according to claim 1, characterized in that the long branches (12b) and the short branches (12a) of the tubes (12)   are respectively arranged in a triangular step.   4 / - Heating cylinder according to one of the   Claims 1, 2 or 3, characterized in that the branches   long (12b) and short branches (12a) of the tubes (12) are respectively arranged so as to each register   inside a generally semicircular section.   / - Heating cylinder according to one of   previous claims, in which the chamber   combustion (10) has a cylindrical shape, characterized in that the end wall (11) of said chamber is a circular plate secured by welding and provided with exhaust orifices (la) into which the branches open short (12a) tubes (12).   6 / - Heating cylinder according to one of the   previous claims, comprising a ferrule (5) to   flange (6) of cross section of the orifice (4) of the wall of the sink (1) and secured inside said orifice for the fixing of the front plate (7), said balloon being carcterized in that said front plate (7) has an ovoid shape combined with the orifice (4) and of dimensions   substantially greater than those of said orifice.   7 / - Heating cylinder called vertical according to   -one of the preceding claims, comprising a wall   cylindrical device (2) of vertical axis, closed by two caps (3), upper and lower, and an orifice (4)   formed in the lower part of said peripheral wall.   8 / - Heating cylinder called horizontal according to   one of claims 1 h 6, comprising a wall   cylindrical device (14) with a horizontal axis, closed by two end caps (15), and an orifice (4) formed in   lower part of a deadites end caps.   9 / - One-piece combustion and heat exchange assembly capable of being removably mounted on   a heating cylinder according to one of claims 1   8, comprising an orifice (4) of oval shape formed in the wall, said assembly comprising s - a front plate (7) provided with an opening (9) and orifices (7b) termed smoke exhaust , and comprising removable fixing means on the wall of the tank (1), - a combustion chamber (10) secured to the front plate (7) so that the opening (9) of said plate opens into this chamber, and provided with an end wall (11) opposite to said opening, - a multitubular exchanger constituted by a plurality of tubes (12), each, generally in the shape of a U, having a branch (12a), called short, secured towards its end on the end wall (11) of the combustion chamber so as to communicate with the interior of said chamber, and a branch (12b), called long, of length above, secured towards its end on the facade plate (7) 'so as to open into the exhaust orifices (7b) of this last, - a burner (B) carried by the front plate (7) so as to communicate with the combustion chamber (10) through the opening (9) of said plate, - and a collector exhaust (13) carried by the front plate (7), facing the exhaust orifices (7b) of said plate, said assembly being characterized in that: - the exhaust orifices (7b) of the front plate (7) are grouped so as to be inscribed inside a section substantially centered on an axis common to the major axis of the orifice (4) of the wall of the tank (1), - the opening (9) and the exhaust port assembly (7b) of the front plate (7) are provided on   the latter so as to be situated respectively on the one hand.   and on the other side of the small axis of symmetry of the orifice (4) of the wall of the tank (1), - the tubes (12) are arranged according to a beam inscribed inside a shaped section general of U with transverse dimensions substantially smaller than those of the orifice (4) of the wall of the tank (1) and so that the long branches (12b) are grouped laterally on one side of the combustion chamber (10) to come out in the exhaust orifices (7b) of the front plate (7), and that the short branches (12a) are grouped at the rear of the combustion chamber (10) in alignment of it.