FR2604778A1 - Heat exchanger with thin and flexible semi-rigid or rigid exchange surfaces - Google Patents

Abstract

Heat exchanger comprising one or more enclosures 1, 2 having a thin wall made of semi-rigid flexible material, which are/is arranged inside a body 3 which is possibly provided with a steam (vapour) outlet 26 and each fixed to a support 4 by its top end, means 5, 6 for delivering a condensible heating gas into the enclosure(s), means 7, 9 for bringing a liquid to be subjected to thermal exchange with the said condensable gas to trickle down on the external face of the wall of the said enclosure(s), means for isolating the atmosphere in the enclosure(s) from that in the body, a chamber 10 collecting the condensates which are intended to be formed in the enclosure(s) and means for compensating for the expansion of the enclosure(s), characterised in that the isolation means comprise at least one means 20, 21 for forming, by means of the condensates, a hydraulic barrier between one or more enclosure(s) and the collector chamber, each of these means extending freely through a passage 12, 13 provided in the wall of the collector chamber and arranged in the body.

Description

Heat exchanger with thin and flexible spare surfaces. semi-rigid or rigid.

 The subject of the present invention is a heat exchanger of the type comprising one or more thin-walled enclosure (s) of flexible, semi-rigid or rigid material, arranged inside a body optionally provided with a steam outlet and fixed (s> each of a support by its upper end, means for distributing a condensable heating gas in the chamber (s), means for causing a liquid to be subjected to heat exchange with said condensable gas to flow on the outer face of the wall of said chamber (s), means for isolating the atmosphere prevailing in the chamber (s) of that prevailing in the body, a collector chamber condensates for å form in the enclosure (s) and means for compensation of the expansion of the enclosure (s).

 One of the difficulties encountered with this type of heat exchanger lies in the significant longitudinal expansion of the exchange surfaces defined by said enclosures which may in particular be plastic.

The use of such surfaces therefore requires the implementation of means capable of compensating for this expansion. Another difficulty lies in the need to extract the condensates forming in the enclosures, without any communication between these enclosures. and the body which are intended to operate at different pressures. To achieve this compensation of the expansion and extraction of the condensates, the known heat exchangers comprise a reduction sleeve integral with the lower end of each chamber, this sleeve being engaged with a soft friction in a lip connection secured to the collecting chamber. The use of such a fanchon obviously does not prevent the passage of a certain amount of heating vapor from the enclosure (s) to the collecting chamber, with the economic disadvantage that this is. In addition, the sliding lip seal implemented in these known exchangers for sealing between the speakers and the body, is a complex and expensive technique.

 The object of the present invention is to overcome these disadvantages. To do this, it proposes a heat exchanger conforming to that defined in the first paragraph of this description and characterized in that the isolation means comprise at least one forming means, using condensates, a guard hydraulic fluid between one or more chambers and the collecting chamber, each of these means extending freely through a passage provided in the wall of the collecting chamber and disposed in the body.

 It will be readily understood that by providing a hydraulic guard between the speakers and the collection chamber, it is avoided that there is communication between these speakers and this chamber and, therefore, it avoids any loss of heating vapor. At the same time, there is no risk of communication between the speakers and the body. It follows that, thanks to the invention, it becomes unnecessary to have at the level of the passages provided on the wall of the collection chamber, means preventing a gas flow from said chamber to said body. It thus becomes unnecessary to use such complex and expensive means as the sliding lip seal used in the prior art.

 According to one embodiment of the invention, each means of forming a hydraulic guard comprises a U-shaped tube whose one end is in communication with the lower end of at least one enclosure and the other end s opens in the collecting chamber.

 According to another embodiment of the invention, each means for forming a hydraulic guard comprises a tube whose one end is in communication with the lower end of at least one enclosure and the other end is opens in the collector chamber, the length of this tube and the level of the condensate to be present in this chamber being chosen to allow the formation of the desired hydraulic guard.

 The expansion compensation means, also included in the construction of the heat exchanger of the invention, may be those used up to now and having the structure recalled above (sliding joint to lift). However, since a gas seal is not required between the collection chamber and the body, these expansion compensation means can be of a very simplified structure in comparison with the means used in the prior art. Thus, these means may in particular comprise one or more first sleeves extending externally to the collecting chamber respectively around the passage or s <s> provided <s> in the wall of this chamber and deflection means provided between or the enclosureRs) and the free opening of the first sleeve (s), to prevent the liquid to flow on the outer face of the speaker or) enters this sleeve or these <s> sleeve.

 These first sleeves therefore provide guiding means for forming a hydraulic guard which, moreover, can slide freely through these first sleeves and said passages provided on the wall of the body, which makes it possible to compensate for the expansion of the enclosures.

 The deflection means are advantageously constituted by as many second sleeves as there are first sleeve (s), each second sleeve sliding around a first corresponding sleeve with a game such that there is in operation, substantially pressure balance between the body and the collecting chamber.

 When in the heat exchanger according to the invention the means) for forming a hydraulic guard comprise said tube or said U-tube, each second sleeve is shaped to close by its upper end around the tube or the tube in U corresponding.

According to one variant, the enclosure (s) may be constituted by at least one group of tubular sleeves, the lower end of all these ducts opening into a condensate trap provided with said tube or said tube.
U; in this case, each second sleeve is shaped to close by its upper end or around this manifold, or around the tube or tube U.

 Since the pressure intended to reign in the enclosures is greater than that intended to prevail in the collector chamber, the condensates undergo a relaxation when they reach this chamber. The vapor produced by this trigger can escape to the body. However, it is preferred to provide said collection chamber with an outlet for this expansion steam. This output can be connected to one of the circuits of a condenser or heater whose other circuit, separated from the preceding by a heat exchange surface, is intended to be traversed by the liquid to be treated which is thus heated. It can alternatively be brought into corrunication with the steam heating circuit of an evaporator, directly or via a steam compressor.

 Moreover, each tube, U-tube and / or condensate trap will advantageously comprise at least one outlet for the incondensables situated above the hydraulic guard, this outlet being able to communicate, via a flexible conduit, with a atmosphere where pressure exists to extract said incondensables.

 It should also be noted that the invention is applicable regardless of the form of the speakers.

 The heat exchanger according to the invention has different applications.

So. it can be used as an evaporator, for example of the falling-water type, optionally inserting into an evaporation unit comprising one or more other evaporators using, if desired, as an addition to heating vapor, the steam trigger produced in the collector chamber, if necessary after compression of this expansion steam; this exchanger can also be used as a distillation apparatus.

Two embodiments of the invention are illustrated in the following description made with reference to the appended drawing in which
FIG 1 is a schematic longitudinal sectional view of a heat exchanger comprising groups of enclosures each constituted by a tube,
FIG. 2 is a schematic longitudinal sectional view along the line A 'of FIG. 3 showing a heat exchanger comprising several substantially parallelepipedic enclosures, and
FIG. 3 is a schematic longitudinal sectional view along line BB 'of FIG. 2.

The heat exchanger shown in FIG. 1 comprises two groups of tubes 1, 2 arranged substantially vertically inside a body 3. For the simplicity of the drawing, only two groups and only three of the tubes have been shown. of each group, it being understood that the actual number of these groups and tubes is generally much higher. The tubes 1, 2 consist of a
Flexible, semi-rigid or rigid material, for example a plastic material.

 The tubes of each group are fixed by their superior extreiity to a tubular plate 4 attempted in the body 3 so as to define, in the upper part of the body 3, a chamber 5 for supplying heating steam, this chamber being for # of an arrival o heating steam. At a certain distance below the tube plate, is also arranged a horizontal partition 7 defining with the side walls of the body and the plate 4, a liquid supply chamber 8 to be treated provided with a liquid inlet 9 to be treated. The partition 7 is provided with passages for the tubes 1, 2, these passages having a diameter slightly greater than that of the tubes so that the liquid can escape from the chamber 8 to run off on the outer surface of the tubes.

 The exchanger object of Figure 1 also comprises a collector chamber 10 condensate to be formed in the tubes 1, 2. This chamber 10 is disposed under the body 3 and separated from the body by the bottom wall 11 of the latter which is provided with two passages 12, 13 arranged respectively substantially in line with the groups of tubes 1, 2. The chamber 10 is further provided with a means 14 for extracting the condensates and a steam outlet.

 Moreover, each group of tubes 1, 2 comprises at its lower end a lower tubular plate 16, 17.

 According to the present invention, the exchanger which has just been described comprises means for forming a hydraulic guard between the tubes 1, 2 and the chamber 10. These means are more precisely constituted by collectors 18, 19 respectively taking birth on the plates 16, 17 around the tubes 1, 2 and narrowing down to finally end with a tube 20, 21 extending freely through the passages 12, 13 to the inside of the chamber 10 to dive into the condensate intended to be present in this room.

 In addition, first sleeves 22, 23 originate on the wall 11 and extend above this wall respectively around the passages 12, 13. Between each lower tubular plate 16, 17 and the passage 12, 13 which corresponds to it , is further disposed a deflection means preventing the trickle liquid from entering through the opening of the sleeves 22, 23. Each deflection means is constituted by a second sleeve 24, 25 sliding around the first sleeve 22, 23 corresponding with a Sufficient clearance so that there is substantially pressure balance between the chamber 10 and the body 3, each second sleeve closing by its upper part on the manifold 18, 19 or, as shown in Figure 1, on the periphery of the lower tubular plate 16, 17.

 The exchanger which has just been described operates in the following manner.

 Heating vapor is brought under pressure into the tubes 1, 2, tubes which, when they are of a flexible material, are maintained in their cylindrical form under the effect of this pressure.

 During its runoff on the outer surface of the tubes 1, 2, the liquid to be treated (any liquid product to heat, concentrate or distill such as for example a dairy product, a hydro-alcoholic solution such as wine, etc. ) undergoes reheating or evaporation as a result of the heat transferred to it by the condensing heating vapor. The vapor possibly generated by the liquid (in the case of evaporation or distillation) is discharged through a vapor outlet 26 provided on the body 3. The liquid then flows on the plates 16, 17 and on the sleeves 24, 25 (The sleeves 22, 23 preventing the liquid from entering the chamber 10> before reaching the bottom of the body 3 from which it is extracted by an extraction means 27.Quant to the condensate formed in the tubes 1, 2, they flow through the collectors 18, 19 to reach the tubes 20, 21 where they form a hydraulic guard with the condensates already present in the chamber 10. Gracie to this guard, it avoids any flow of heating steam tubes 1 , 2 to said chamber 10.

 Moreover, the sleeves 22, 24 and 23, 25 compensate for the expansion of the tubes 1, 2 by relative sliding relative to each other.

 Since the chamber 10 is at a pressure lower than that prevailing in the tubes 1, 2, the condensates which reach it undergo a relaxation and the flash vapor thus produced is then discharged through the outlet 15. However, if desired, this steam expansion can also be admitted into the body 3 since the latter and the chamber 10 are substantially squeeze pressure from the existing clearance between the sleeves 22 and 24 and between the sleeves 23 and 25.

 It will further be noted that the collectors 18, 19 and / or the tubes 20, 21 may be provided, above the hydraulic guard, with orifices 28 preferably distributed around the periphery of these collectors and tubes, orifices through which evacuated the incondensables. Normally, these incondensables reach the chamber 10 from which they are extracted at the same time as the condensate expansion steam, either via the outlet 15 or via the outlet 26. However, it is possible, in a variant, to connect the orifices 28 to flexible ducts (not shown) whose free end results in an atmosphere where there is a pressure allowing the evacuation of said incondensables.

 The heat exchanger object of Figures 2 and 3 comprises a number of heat exchange surfaces 29 constituted by substantially parallelepiped enclosures arranged vertically and parallel to each other. Each enclosure contains at its upper part a duct 30 extending longitudinally in said enclosure, this duct being secured by one of its ends to the upper part of one of the side walls of a body 31, so that that the speakers are suspended in this body. Furthermore, each duct 30 is provided with a heating vapor inlet 32. Each duct 30 is furthermore provided with one or more openings 33 allowing the heating vapor supplied by the inlet 32 to enter the duct 30. the inside of the enclosure.Au above each chamber and all along the latter, are arranged nuclei to distribute a liquid to be treated on the outer surface of the enclosure. These means are, in this case, constituted by nozzles 34 for spraying the liquid. These nozzles, secured to the upper wall 35 of the body 31, communicate with a liquid supply chamber 36 whose bottom wall coincides with the wall 35, the chamber 36 being provided with a liquid inlet 37.

 Furthermore, each chamber is provided at its base with an extended opening by a vertical tube 38 which extends through a passage 39 formed in the upper wall of a chamber 40 collector of condensates intended to form in the enclosures 29. This chamber 40 is disposed in the body 31 under the speakers 29, it is common to all said speakers and the size of the passages 39 is chosen so that each tube 38 can slide freely in the corresponding passage. The chamber 40 also has an extension 41 located outside the body 31, this extension being provided with an outlet 42 of condensate and steam.

 On the other hand, a first sleeve 43 extends externally to the chamber 40 around each passage 39. Above each sleeve 43 are disposed deflection cores preventing the liquid streaming on the speakers from entering the chamber 40 These means are, in this case, constituted by a second sleeve 44 adapted to slide around the first sleeve 43 corresponding with a game such that in operation there is substantially pressure balance between the chamber 40 and the body 31 this second sleeve closing by its upper part around the corresponding tube 39.

 The heat exchanger thus described is completed by an outlet 45 of vapor provided on the body 31 at the upper part of the latter, by extraction means 46 of treated liquid provided at the lower part of the body 31 and optionally by means of uncondensable outputs similar to those referenced 28 in FIG.

 The operation of the exchanger object of Figures 2 and 3 is quite identical to that of the exchanger object of Figure 1.

 If desired, a condenser having two circuits separated by a heat exchange surface may be provided, one of these circuits being connected to the spruce 15 or the outlet 42 (in the latter case a liquid separator steam is disposed between said outlet and said circuit) and the other circuit is disposed in the path of the liquid upstream of the inlet 9 or 37, which liquid is thus heated.

 When the exchangers described above are intended to be integrated in a unit comprising several evaporators, the expansion steam produced in the chamber 10 or 40, possibly after compression, will be used as a supplement to the heating vapor necessary for the operation of the reactor. one of said evaporators.

Claims (12)

REVEBDICATIONS  1. Heat exchanger of the type comprising one or more thin-walled enclosures (1, 2; 29) of flexible, semi-rigid or rigid material such as a plastic material, arranged inside a body (3; 31) optionally provided with an outlet (26; 45) of steam and each fixed to a support (4; 30) by its upper end, means (5,6; 32,33); ) of distribution of a condensable heating gas in the chamber (s), means (7, 9, 34) for causing a liquid to be subjected to heat exchange with said condensable gas to flow on the outer face of the wall of said chamber or enclosures, means for isolating the atmosphere prevailing in the chamber (s) from that in the body, a chamber for collecting condensates intended to form in the chamber; the enclosure (s) and means for compensating for the expansion of the enclosure (s), characterized in that the isolation means comprise at least one means ( 20,21; 38) forming, with the help of the condensates, a hydraulic guard between one or more chambers (s) and the collecting chamber, each of these means extending freely through a passage (12,13 ; 39) provided in the wall of the collecting chamber and disposed in the body.  2. Heat exchanger according to claim 1, characterized in that each means for forming a hydraulic guard comprises a U-shaped tube whose one end is in communication with the lower end of at least one enclosure and the the other end opens into the collecting chamber.  3. Heat exchanger according to claim 1, characterized in that each means for forming a hydraulic guard comprises a tube whose one end is in communication with the lower end of at least one enclosure and the other end opens into the collection chamber, the length of this tube and the level of the condensate to be present in this chamber being selected to allow the formation of the desired hydraulic guard.  4. Heat exchanger according to claim 1, 2 or 3, characterized in that the expansion compensation means comprise one or more first seals (22,23; 43> extending1 externally to the collecting chamber, respectively around the passage (s) provided (s) in the wall of this chamber and deflection means, provided between the chamber (s) <s) and the free opening of the first sleeve (s), to prevent that the liquid does not penetrate in this or these last (s).  5. Heat exchanger according to claim 4, characterized in that the deflection means consist of as many second sleeve (s) (24,25; 44) as there are first sleeve (s), each second sleeve sliding around a first corresponding sleeve with a game such that there is, in operation, substantially pressure balance between the body and the collecting chamber.  A heat exchanger according to claim 5, wherein each means for forming a hydraulic guard comprises said tube or said U-shaped tube, characterized in that each second sleeve is closed at its upper end around the tube or tube. U correspondent.  7. Heat exchanger according to claim 5, wherein the enclosures are constituted by at least one group of tubular sleeves (i (1,2), the lower end of all these ducts opening into a manifold (18,19) of condensate provided with said tube or said U-tube, characterized in that the second sleeve closes at its upper end around this manifold, tube or tube U.  8. Heat exchanger according to one of the preceding claims, characterized in that the collector chamber is provided with an outlet (15) for the steam produced by the expansion of the condensate.  9. Heat exchanger according to claim 8, characterized in that this output is in communication with one of the circuits of a condenser or heater whose other circuit, separated from the previous by a heat exchange surface, is intended to be crossed by the liquid to be treated.  10. Heat exchanger according to claim 8, characterized in that this outlet is in communication with the heating vapor circuit of an evaporator. directly or via a steam compressor.  11. Heat exchanger according to one of claims 2 to 10, characterized in that each tube, U-tube or condensate collector comprises at least one outlet (28) for the incondensables located above the hydraulic guard.  12. Heat exchanger according to claim 11, characterized in that each output for the incondensables communicates via a flexible conduit with an atmosphere or reigns a pressure for extracting said incondensables.