FR2907539A1 - Exchanger-condenser for e.g. domestic condensing boiler operating with fuel oil, has exchangers arranged in series in circuit to be successively traversed by cooling liquid, and disposed in parallel and simultaneously traversed by water - Google Patents

Abstract

The exchanger-condenser (1) has a graphite core (2) with a channel for the passage of combustion gas and smoke longitudinally traversing the core and emerging on its upper and lower edges. Each of two lateral exchangers (45, 46) is retrieved against front and rear surfaces (14, 15) of the core. The exchangers have hollow interior chambers room, respectively, in which the cooling water circulates. The lateral exchangers are arranged in series in a fluidic circuit to be successively traversed by the cooling liquid, and disposed in parallel and simultaneously traversed by the cooling water.

Description

The present invention relates to a heat exchanger-condenser for boiler with

  condensation operating preferentially with fuel oil. The invention relates more particularly to domestic condensing boilers. However, its principle could also be applied to boilers of higher power. Condensing boilers are interesting for many reasons. They allow first to increase the thermal efficiency of at least 10% and thus to achieve an interesting economy. In addition, the gases and combustion fumes exit through the flue gas, cooled and freed of a large part of their moisture.

  However, the condensates from the condensation of the gases and combustion fumes of a hydrocarbon fuel are strongly acidic. The component parts of the heat exchangers must be able to withstand chemical corrosion sufficiently to remain in working order for several years. However, this quality is characteristic of noble or chemically inert materials. The cost price of these is high and the boiler market in general and domestic boilers in particular can not bear a significant additional cost on this product, even if the yield gain is real. Manufacturers have turned to more common and less expensive materials known to be chemically inert or at least non-corrodible by aggressive chemicals such as acids. In this category, we can mention graphite which is already used in laboratories and chemical industries.

  There is thus known a condenser heat exchanger for condensation boiler, formed of a bundle of graphite tubes placed in a stainless steel enclosure 2907539 2. The combustion gases and fumes pass through this chamber and condense against the cold walls of the graphite tubes through which the return water from the radiators to the boiler passes.

With this conventional exchanger, the fumes and acid condensates come into contact, not only with the graphite tubes, but also with the walls of the stainless steel enclosure. To protect them from corrosion, they must be treated against corrosion or covered with a layer of expensive protective coating. In addition, by its constitution, such a tube bundle exchanger requires a complex assembly, with multiple points of attachment and sealing which are all potential risks of leakage. The object of the invention is to provide a condenser heat exchanger condenser of much simpler construction and assembly and does not require the use of expensive materials or expensive coatings. Advantageously, the heat exchange for lowering the temperature of the gases and fumes is carried out on flat surfaces in the exchanger according to the invention. To solve this technical problem, the invention provides a condenser heat exchanger-condenser, traversed by the gases and combustion fumes from the furnace of the boiler 30 and cooled by the circulation of a coolant to cause the condensation of some of these gases and combustion fumes. This exchanger-condenser comprises in the upper part a supply of gases and combustion fumes 35 and in the lower part an evacuation thereof and a collection of condensates resulting from their condensation.

According to the invention, it comprises: a core, the part of which in contact with the combustion gases and fumes and their condensates is resistant to corrosion, and which comprises channels for the passage of gases and combustion fumes, traversing the core substantially longitudinally and opening on its upper edge and its lower edge; and two lateral heat exchangers, one on each side of the core and each containing a hollow inner chamber in which the cooling liquid circulates, these lateral heat exchangers being connected in series or in parallel. According to a preferred embodiment of the invention, the core consists of two plates having on one of their large face substantially parallel and longitudinal grooves, opening on their respective upper and lower edges. These plates are then juxtaposed to form the core, a grooved face against the other grooved face so as to form the passage channels of the gases and combustion fumes. Preferably, the heat exchanger-condenser according to the invention also comprises a fumes and combustion gas supply guide disposed in the upper part and a condensate collector in its lower zone forming a flue gas box. Advantageously, with the exchanger-condenser according to the invention, the flue gases, the combustion gases and their acidic condensates are found only inside the core channels, made of a material resistant to corrosion, preferably in graphite, and are not in contact with the side exchangers. These side exchangers, only in contact with the cooling water, require no protective coating. They can be made of a conventional material and economic, for example cast iron, 2907539 4 aluminum, steel, or even plastic, or any other suitable material. The inner chamber of each of the lateral exchangers of the exchanger-condenser according to the invention preferably has at least one, and preferably a plurality of partition walls delimiting a baffled waterway serving to lengthen the path of the cooling water circulating in the corresponding inner chamber 10 and accelerate its flow. In the case of a hydraulic assembly in series, the two inner chambers of the lateral exchangers communicate with each other by one or more hydraulic connections passing through the core or outside thereof, and are thus traversed successively by the 'cooling water. It is also possible to envisage an embodiment in which these two inner chambers are arranged, no longer in series, but in parallel on the flow path of the cooling water. In this case, the two chambers are parallel paths that can be independent. Other characteristics and advantages of the invention will appear on reading the following detailed description, which description is made with reference to the appended drawings, in which: Figure 1 is a front perspective view of a heat exchanger-condenser according to a first embodiment of the invention; 30 . Figure 2 is a rear perspective view of the exchanger-condenser according to the first embodiment of the invention; . Figure 3 is an exploded perspective view of the various elements of the exchanger-condenser according to the first variant of the invention; . Figure 4 is a perspective view of the outer face of a side exchanger of the condenser exchanger according to the first variant of the invention; . Figure 5 is a perspective view of the open inner face of a side exchanger of the exchanger-condenser according to the first variant of the invention; . Figure 6 is a perspective view of the inner face of one of the plates forming the core of the exchanger-condenser according to the first variant of the invention; . Figure 7 is a top perspective view of the core of the exchanger-condenser according to the first variant of the invention, the arrows embodying the gases and combustion fumes and the drops the condensates; . FIG. 8 is an exploded perspective view of a heat exchanger-condenser according to a second variant of the invention, in series connection of the lateral heat exchangers by a tubular external hydraulic connection, the flue gas supply guide and the condensate collector. not represented; . Figure 9 is a schematic exploded perspective view of a heat exchanger-condenser according to a third variant of the invention for mounting in two parallel ways, without its fumes guide and its condensate collector; . FIG. 10 is a diagrammatic cross-sectional view of a heat exchanger-condenser according to a fourth variant of the invention, in series mounting of the lateral exchangers by an external hydraulic connection with a biconical connection; . FIG. 11 is a diagrammatic cross-sectional view of a heat exchanger-condenser according to a fifth variant of the invention in series connection of the lateral exchangers by two external hydraulic connections with biconical coupling. The exchanger-condenser according to the present invention will now be described in detail with reference to FIGS. 1 to 11. The equivalent elements shown in the various figures will bear the same numerical references. In this description, the notions of front and rear, top and bottom, horizontal and vertical, etc. will be defined as a function of the orientation adopted by the exchanger shown in the various figures. . It is obvious that this orientation, although preferential, will not necessarily be kept in use. In the appended figures, there are shown several variants of a heat exchanger-condenser 1 according to the invention which will be described below. It should be understood that these variants are only preferred embodiments of the invention and are not in any way limiting.

The exchanger-condenser 1 according to the invention comprises a core 2 whose part in contact with the combustion gases and fumes and their acidic condensates is resistant to corrosion. This characteristic can be obtained by means of a protective coating applied on this part or be a property of the constituent material of this part of the core 2 or of all of it. For example, the core 2 may be entirely made of graphite. This core 2 is a preferably substantially parallelepipedal body, preferably formed of two juxtaposed plates, one before 3 and the other rear 4. These two plates 3 and 4, placed opposite one another, are intended to be juxtaposed at their large respective inner face, namely the rear face 5 for the front plate 3 and the front face 6 for the rear plate 4, these two faces 2907539 7 being pressed against each other to form an inert body called core, to be traversed by the gases and combustion fumes 7 of a boiler. Each of these plates, 3 and 4, has a series of grooves 8 and 9, preferably substantially vertical and substantially parallel to each other, open at each inner face, respectively 5 and 6. These grooves 8 and 9 also open on The upper edges 10 and 11, respectively, and lower, respectively 12 and 13, of each of these plates 3 and 4. The grooves 8 and 9 are molded or machined in the thickness of the plate to a depth preferably more important possible given the necessary strength and rigidity of the plate, but without crossing the body thereof at its outer face, respectively corresponding to the front face 14 for the front plate 3 and the rear face 20 15 for the back plate 4, which is left intact. On: The preferred example shown, the grooves 8 and 9 have a section of substantially rectangular shape. However, this shape may be different and for example triangular, rounded, rectangular with rounded bottom or other. The grooves 8 and 9 are arranged so as to meet each other when the two plates 3 and 4 are juxtaposed to form the core 2. They then form longitudinal channels 16, 30 to the core 2, which open at the upper edges 17 and bottom 18 of the core 2 and are intended for the passage of combustion gases and fumes 7. The core 2 is preferably made from two plates 3 and 4 grooved juxtaposed 35 to simplify its manufacture. However, this core 2 could also be made in one piece, such as a one-piece body hollowed out of longitudinal channels, with a different manufacturing process. In the first embodiment of the invention shown in FIGS. 1 to 7, the core 2 also has transverse through-passages 19, for example in the form of substantially cylindrical ducts 20 and 21 respectively passing through each of the plates 3. and 4 and opening on both sides thereof, at their front face 14 and 6 and their rear face 5 and 15. The ducts 20 and 21 are provided so as to be in facing relation when the front 3 and rear 4 plates are juxtaposed, each duct of one of the plates being in the extension of the corresponding duct 15 of the other plate so as to form the through passages 19 of the core 2. These through passages 19 are made in a portion of the core 2 having no passage channel 16 for flue gases and fumes, so as not to be in communication therewith. The ducts 20 and 21 are thus made in a non-grooved portion of the plates 3 and 4. In the example shown, the ducts 20 and 21 have been assembled in the upper part of a non-grooved strip, referenced respectively 22 and 23. on the plates 3 and 4, extending for example in the middle of each plate 3 and 4. It is obvious that this is only an exemplary embodiment. The non-grooved portion of the core 2 is not necessarily central and may be at any level of the plates, the conduits 20 and 21 may even be distributed over several non-grooved strips 22, 23. However, the non-grooved portion of The core is preferably as limited as possible so that the exchange surface is maximum. In addition, the ducts 20 and 21 may be distributed at any spacing, regular or not, and at any height of the non-grooved strip (s) 22, 23. Furthermore, the number and the shape of the transverse through-passages 19, and thus of the conduits 20 and 21, are not limited to those shown but may be arbitrary depending on the intended application. As will be seen hereinafter, these transverse through-passages 19 place in fluid communication the two lateral exchangers of the exchanger-condenser 1 according to the invention and thus allow a cooling liquid 24, preferably the return water of the radiators, to switch from one side to another of the core 2.

However, this setting in fluidic communication remains optional or can be carried out by means outside the core 2 which will be described several examples in the remainder of this description. In this case, the transverse through-passages 19 are not necessary and the plates 3 and 4 can be grooved over almost their entire width as in the examples shown in FIGS. 8 to 11. The exchanger-condenser 1 according to the invention 25 also comprises a guide 25 for supplying gases and combustion fumes 7, which is assembled above the core 2. This feed guide 25 allows the combustion gases and fumes 7 to be channeled from the furnace to the furnace. input of the channels 16 of the central core 2.

For this, the preferential feed guide 25 shown has an inlet piece 26 of frustoconical general shape intended to be placed in communication by its circular rear orifice 27 with the orifice or the pipe for evacuation of gases and fumes. combustion of the fireplace. The connection between the two is for example made by means of a bearing flange 28 provided with lugs 29 having an attachment hole 30 for the passage of known assembly means, such as for example tie rods. assembly or screw-nut assemblies.

The inlet piece 26 gradually fades and opens into a distribution dome 31, for example of generally substantially trapezoidal shape, whose bottom is open and whose role is to distribute the gases and combustion fumes in the various 10 channels 16 of the core 2. The distribution dome 31 rests on the upper edge 17 of the core 2 via a peripheral flange 32. It is assembled to the rest of the exchanger-condenser 1 for example by means of tabs 15 fasteners such as 33, pierced with a circular opening 34 intended to cooperate with an assembly means not shown. However, the feed guide 25 for combustion gases and fumes may have any other form different from that shown as long as it allows it to perform its function. The exchanger-condenser 1 according to the invention further comprises a collector 35, assembled under the core 2 and whose inner space 36 communicates with the output of the channels 16 located at the lower edge 18 of the core 2. The collector 35 is for example in the form of a trapezoidal tray 37 with side edges 38 converging downwards.

It is open at the top and is brought against the lower edge 18 of the core 2 preferably by means of a peripheral rim 39. The function of the collector 35 is to evacuate the combustion gases and fumes 7 and to collect them. 35 condensates 40 resulting from the condensation of the gases and combustion fumes 7 inside the core 2 and flowing by gravity along the channels 16 up to 2907539 11 their output at the lower edge 18 of the core 2. The gas and combustion fumes 7 and the liquid condensates 40 are respectively represented by white arrows and drops in FIG. 5. The circulation of the coolant 24 is schematically represented by black arrows in different figures. The condensates 40 ending in the manifold 35 are channeled to a discharge port 41 which can be extended by a tubular birth 42. These acid condensates are then discharged through a not shown exhaust duct. They are neutralized before being rejected. The collector 35 also has an outlet port 43 for flue gases and combustion gases 7, through which the cooled and dried combustion gases and fumes escape from the core 2, which can also be extended by a tubular birth 44. outlet port 43 is provided to be connected to the chimney by a flue. The core 2 is flanked on each of its large outer lateral faces, namely the front face 14 of the front plate 3 and the rear face 15 of the rear plate 4, of two lateral exchangers, respectively 45 and 46, in which passes the coolant, preferably consisting of return water heating elements releasing heat in the rooms and premises. The temperature of this water depends on the operating point of the heating system. In any case, it makes it possible to easily condense the combustion gases and fumes 7 that come out of the furnace at temperatures of the order of 180.degree. C. The lateral exchangers 45 and 46 each contain a hollow interior chamber 47 and 48, respectively. , preferably substantially flat, which allows the circulation of the cooling water.

The interior space of these chambers 47 and 48 is preferably partitioned by one or more partition walls 49, 50 forming a meandering path for the coolant 24 so as to lengthen its path and thereby increase its time of presence in the exchanger. An example of arrangement of such partition walls 49, 50 has been given in a nonlimiting manner in the accompanying figures.

The general shape of each lateral exchanger 45, 46 is preferably that of a substantially flat pocket, of which a large outer face, respectively 51 and 52, is closed and preferably comprises one or more stiffening ribs 53, 54, and the large inner face, respectively 55, 56, is intended to be attached against the corresponding face of the core 2, namely in the example shown the front face 14 of the front plate 3 or the rear face 15 of the rear plate 4 .

The large inner face 55, 56 of the side exchangers 45 and 46 can be opened or closed by an exchange wall (not shown). It is attached to the corresponding face of the core 2 by its perimeter edges 57, 58 in the case of an open face or by its closure plane in the case of a closed face. It is of course advantageous to improve the heat exchange, that the coolant 24 is directly in contact with the corresponding wall of the core 2 within which pass the gases and flue gases to be condensed. The lateral exchanger variant with an inner face 55, 56 open is therefore preferential. However, an inner-face variant 55, 56 closed by an exchange wall is also feasible and within the scope of the invention. The lateral exchangers 45 and 46 may be provided, preferably at their lateral edges 59, 60, with assembly lugs 61 and 62 traversed by a cylindrical passage 63, 64 for fastening means, for example connecting rods 5 such as 65 providing the connection link between the two side heat exchangers 45, 46 opposite and thus the assembly of the core and side heat exchangers. Each side exchanger 45, 46 has at least one inlet or outlet port 66, 67 for the cooling water. Depending on the application, the two side exchangers 45 and 46 of the exchanger-condenser 1 of the invention can be arranged in series, that is to say placed one after the other in the circuit. fluidic to be passed successively by the coolant. Such an arrangement makes it possible to lengthen the circuit of the coolant to increase its time of presence in the heat exchanger and thereby increase heat exchange. The two lateral exchangers 45 and 46 can also be arranged in parallel and thus simultaneously traversed by the coolant, which reduces the pressure drop.

Several non-limiting examples of such hydraulic assemblies have been shown in the various figures and will now be described. Hydraulic communication between the exchangers may be provided either internally, through the core 2 through transverse passages such as 19 as shown in FIGS. 3, 6 and 7, or by one or more external hydraulic connections. (s). According to the arrangements, these hydraulic connections can be used for parallel or series installations. According to the conventional parallel assembly shown in FIG. 9, each lateral exchanger 2907539 14 45, 46 independently comprises a first orifice, respectively 66 and 67, possibly provided with a tubular birth, respectively 68 and 69, which allows the entry of the coolant, and a second port, respectively 70 and 71, may also be provided with a tubular birth such as 72, which serves for the coolant outlet. The two exchangers 45 and 46 do not communicate with each other and are traversed independently and simultaneously by the coolant entering through the first orifice 66, 67, and emerging through the second orifice 70, 71 of each of the exchangers side. The sharing of the streams in parallel comes from an external assembly not shown. Advantageously, the orifice 66, 67 serving as an inlet may be situated towards the bottom of the exchanger and the orifice 70, 71 serving as an outlet towards the top thereof. Of course, this arrangement may be different and is not necessarily the same for the two lateral exchangers 45, 46. The two lateral exchangers 45 and 46 may advantageously be identical and simply rotated with respect to each other, as in the embodiment of FIG. 9, which makes it possible to produce them from the same mold. In the case of a series assembly, each side exchanger 45, 46 has only one orifice, respectively 66 and 67, one of them 30 serving for the entry of the coolant and the other for its release. Such a series connection can be obtained with a hydraulic communication of the two lateral exchangers 45 and 46 through the core 2 by one or more transverse passages 19 as in the embodiment of Figures 1 to 7. The hydraulic connection can also be carried out by means of an outer tubular section 73 connecting the two lateral heat exchangers 45 and 46, as in the variant of FIG. 8. In this case, in addition to a first orifice 66, 67 serving for the inlet 5 or the outlet of the coolant, each lateral exchanger 45, 46 further comprises a second orifice 70, 71 intended to be connected to one of the ends, respectively 74 and 75, of the outer tubular section 73.

Another variant of series assembly, shown diagrammatically in FIG. 10, consists in hydraulically connecting outside the core 2 the two lateral exchangers 45 and 46 between them, for example between two tie-rods 65, by two connecting arms. respectively 76 and 77, each formed in the mass of one of the lateral exchangers and extending in the direction of one another. These two connecting arms 76, 77 are connected and placed in fluidic communication preferably by conical fitting using a biconical connector 78 called a nipple. In the embodiment shown in Fig. 10, the coolant inlet 24 is at the front side heat exchanger 45 through its port 66 and the outlet of this liquid is through port 67. rear side heat exchanger 46, for example by means of conventional hydraulic connections. As shown in FIG. 11, it is also possible to envisage a connection using two external hydraulic connections arranged one on each side of the heat exchanger-condenser according to the invention, these connections being made each time by two connecting arms 76, 77 each formed in the mass of one of the lateral exchangers, respectively 45 and 46, conically fitting each using a biconical connector 78. Such an assembly assumes for example an arrival of the coolant 24 in the low position of one of the lateral exchangers (the front lateral exchanger 45 in the example of FIG. 11), parallel hydraulic connections between the lateral exchangers in the upper part and an outlet of the coolant 24 in the lower position on the other lateral exchanger (rear exchanger 46). This arrangement is a series arrangement with two passages in parallel, external to the core 2.

Where possible, it may be advantageous to use symmetrical parts that can possibly emerge from the same mold. Obviously, the invention is not limited to the preferred embodiments described previously and shown in the various figures, the skilled person can make many modifications and imagine other variants without leaving the scope, neither of the scope of the invention.

Claims (15)

  1. Heat exchanger-condenser (1) for a condensing boiler, through which flue gases and fumes (7) from the furnace hearth and cooled by the circulation of a coolant (24) to cause the condensation of a part of these gases and combustion fumes (7), exchanger-condenser comprising in the upper part a supply of gases and combustion fumes (7) and in the lower part an evacuation thereof and a collection of condensates (40) resulting their condensation, characterized in that it comprises: - a core (2), whose part in contact with the combustion gases and fumes (7) and their condensates (40) is resistant to corrosion, and which comprises channels (16) for the passage of gases and combustion fumes (7), traversing the core substantially longitudinally and opening onto its upper edge (17) and its lower edge (18); and - two lateral heat exchangers (45, 46), one on each side of the core (2) and each containing a hollow inner chamber (47, 48) in which the coolant (24) circulates, these lateral heat exchangers (45, 46). ) being mounted in series or in parallel.   2. exchanger-condenser according to claim 1 characterized in that the core (2) is graphite.   3. exchanger-condenser according to any one of the preceding claims characterized in that the core (2) consists of two plates (3,   4) having on one of their large face (5, 6) grooves (8, 9) substantially parallel and longitudinal, opening on their upper edges (10, 11) and lower (12, 13) respectively, these plates ( 3, 4) being juxtaposed to form the core (2), a grooved face (5) against the other grooved face (6) so as to form the channels (16) for the passage of gases and combustion fumes (7). ). 4. Heat exchanger according to any one of the preceding claims, characterized in that the inner chamber (47, 48) of the side exchangers (45, 46) comprises at least one partition wall (49, 50) forming a path meander for the coolant (24). 10   5. exchanger-condenser according to any one of the preceding claims, characterized in that each lateral exchanger (45, 46) is a substantially flat pocket having a large outer face (51, 52) closed and a large inner face (55, 56) reported against the corresponding face of the core (2).   6. Heat exchanger according to the preceding claim characterized in that the large inner face (55, 56) of the side heat exchangers 20 (45, 46) is open.   7. exchanger-condenser according to claim 5 characterized in that the large inner face (55, 56) of the side exchangers (45, 46) is closed by an exchange wall attached to the corresponding face of the core (2).   8. exchanger-condenser according to claim 5 characterized in that the large outer face (51, 52) closed lateral exchangers (45, 46) comprises at least one stiffening rib 30 (53, 54).   9. exchanger-condenser according to any one of the preceding claims characterized in that the core (2) and the side exchangers (45, 46) are assembled by tie rods (65). 35   10. Heat exchanger-condenser according to any one of the preceding claims characterized in that the side exchangers (45, 46) are mounted in series, the fluid communication between them being effected by at least one transverse passage (19) passing through the nucleus (2).   11. Heat exchanger according to any one of claims 1 to 9 characterized in that the side exchangers (45, 46) are connected in series, the fluid communication between them being effected by at least one hydraulic connection external to the core. (2). 10   12. Heat exchanger according to the preceding claim characterized in that the external hydraulic connection to the core (2) is an outer tubular section (73) connecting between the two side exchangers (45, 46). 15   13. Heat exchanger according to claim 11 characterized in that the external hydraulic connection to the core (2) is achieved by means of two connecting arms (76, 77), each formed in the mass of one of the side exchangers ( 45, 46) extending in a direction towards each other and conically fitted by means of a biconical connector (78).   14. Heat exchanger according to any one of claims 1 to 9, characterized in that the lateral exchangers (45, 46) are connected in parallel, each lateral exchanger (45, 46) being independently provided with a first orifice ( 66, 67) of coolant inlet (24) and a second cooling fluid outlet (24, 71).   15. Heat exchanger-condenser according to any one of the preceding claims characterized in that it further comprises a flue gas supply guide and combustion gas (25) disposed in the upper part and a condensate collector (35) forming smoke box in its lower area.