FR2554915A1 - Heat exchanger applied to the farm-produce industry - Google Patents

Abstract

The subject of the present invention is a heat exchanger for the exchange between a liquid and a (heating or refrigerating) heat-exchange fluid consisting of at least on enclosure in which heat-exchange elements are arranged. It is characterised by the fact that the said elements consist of embossed plates 1, 2 formed by the superposition of metal sheets between which the embossing creates flow tubes, a heat-exchange fluid flowing in each of the tubes of each of the plates, the liquid being made to flow along the exchange surfaces of the said plates 1, 2.

Description

AGRICULTURAL APPLIED HEAT EXCHANGER
The present invention relates to heat exchangers of a new type which find particular application in the food industry and the corresponding heat treatment process.

 In this area, we are looking in particular for a large number of characteristics that are sometimes uncommon in other types of industry.

 Heat exchangers like all containers and equipment for food use must be unalterable and easy to maintain or even sterilize, hence the use of stainless steel.

 they must be suitable for very variable working conditions: with regard to the exchangers, in particular, they can operate at very different temperatures possibly under very variable pressures, and either with liquid / liquid exchange, or with gas / liquid exchange (As in the case of cooling by refrigerant gas. The various contents can be acid or alkaline, aggressive or not, difficult or not to homogenize especially if they are not constituted by a single homogeneous phase.

 In addition, in many specific agrifood fields, we find substances containing living organisms such as bacteria or yeasts which require to work within the limits of often very low temperature differences which poses serious problems of regulation and homogenization. in particular of temperature, and, in the case of heat exchangers, considerably reduces the yields.

 With regard to the heterogeneities of constitution, as in wine applications, for example, it is known that the exchangers must also not be obstructed by the presence of dry matter: in the treatment of musts, for example, pips, skins, grated and other fragments are suspended in the liquid and can cause all kinds of fillings.

In the prior art, many types of exchangers are used; we can mainly quote:
- plate heat exchangers which accept a loss of efficiency due to
circulation channels wide enough to avoid blockage, which
are relatively inexpensive, but only accept exchanges
liquid / liquid and not gas / liquid;
- counter-current tube exchangers, frequently comprising
the liquid circuit of the removable connection ends for faci
liter cleaning, can admit the passage of a nerdy: these
models are expensive;
- gas / liquid exchangers, by coil included in the tank, present
both cleaning difficulties (blocking of materials between the spinnakers
res of the coil or between the coil and the walls) and making
necessary the presence of an agitator in the tank to obtain a
suitable exchanger efficiency.

 The exchangers according to the invention provide solutions to the problems set out above and improvements to the existing solutions.

 They are in the form of one or more enclosures or tanks, one or more walls of which are constituted by double plates, for example embossed by stamping, the liquid to be treated being in contact with these plates or trickling thereon, one or several heat transfer fluids circulating inside the tubes formed by the stamped parts of these various plates. These fluids can be circulating or refrigerating (for example a fluid during expansion). This arrangement makes it possible to present a smooth exchange surface without recesses which would cause the accumulation of suspended matter which would cause the reduction of the exchange capacity and sometimes even stop the circulation (phenomena well known in conventional devices) .The various circulation tubes can therefore be traversed by one or more heat transfer fluids or at identical or different temperature and pressure conditions.

 Each tank thus produced can have any shape, for example, prismatic and / or cylindrical and / or conical, preferably with a vertical axis.

 The embossed plates can be arranged on the internal face of the external walls or form these external walls themselves and / or internal divisions.

 These plates can be secured to the exterior walls, bottoms, covers, hatches or access doors. They can constitute ears or baffles in the interior chamber of each tank.

 The various plates can be mounted totally or partially independent and / or in series and / or in parallel. They can therefore contain a fluid circulating at temperatures which differ from one plate to another, which allows regulations and, better still, programming.

 To better understand the technical characteristics and advantages of the present invention, we will describe embodiments thereof, it being understood that these are not limiting as to their mode of implementation and to the applications that can be made of them. to do.

We will refer to the following figures which schematically represent:
- Figures 1 and 2, an axial vertical section and a horizontal section
according to aa 'on a tank according to the invention;
- Figures 3 and 4, axial vertical sections of devices will
laughing at the device of Figure 1 (the section
of Figure 3 is partial for the upper part);
- Figure 5, a vertical section on a variant device of
that of Figure 1; and
- Figures 6A to F, views of plates deployed flat.

 The generally cylindrical tank 30 has a bottom 31 and is closed by a cover 32 using any conventional device such as screws or clamping cylinders 18, a seal 21 being interposed between cover and upper edge of the cylindrical wall of the tank 30.

The internal face of the cylindrical wall is lined with a double heat exchange plate constituted by a cylindrical plate 1 or several juxtaposed plates. These plates can be constituted by a single embossed sheet as has been said above joined by any suitable means to the cylindrical wall of the tank 30, the wall and sheet assembly forming exchange plate, or by a set of two sheets integral with each other, attached to said inner face of the outer wall. In the first case, the heat transfer fluid circulates between embossed sheet and cylindrical wall, in the second between the two sheets, the internal sheet being embossed and that adjoining the wall of the tank 30 is preferably smooth and adapted so as to leave no possibility of penetration of solid particles between the cylindrical wall of the tank 30 and plate 1.

Inside the tank is disposed concentrically with the outer wall a double embossed plate 2. Each of the two constituting plates can be embossed or one embossed, the other smooth. This double plate therefore provides an annular peripheral chamber 3 and a central chamber 11. The double plate is fixed to the bottom 31, which isolates the two chambers 3 and 11 at the bottom.

 The double plate can have a single circuit or several as for plate 1. It will be noted that the circuit arranged by the embossing can form one or more coils and / or one or more networks of interconnected tubes which allows all configurations and therefore all definition of temperatures and gradients.

 Such an arrangement of the plates allows easy access to the tank by opening the cover, and easy maintenance.

 The liquid to be treated is introduced at 6 near the bottom of the tank and preferably tangentially so that it circulates in a spiral in the annular chamber 3, its flow rate being regulated by the external pump 13 which drives the liquid by delivery. Those skilled in the art can therefore optimize the flow rate so that the exchange surface is' scanned, per unit of time, by the quantity of liquid corresponding to the optimal exchange capacity to ensure the transfer of the necessary calories.

 This exchange capacity can be niodified by varying the flow rate of the pump (for example, motor with several speeds or with adjustable speed, and the like). Another feature of the invention resides in the fact that the height h. of the internal double plate 2 is less than that of the external plate 1 so that the liquid circulating in the chamber 3 overflows through the space 10 in the chamber 11 in the direction of the dotted arrow and comes to trickle on the face internal of the double plate 2 which doubles the exchange surface of the double plate 2. The return of the liquid takes place by the return discharge 12 provided at the bottom 31 of the central chamber 11 and the pipe t.

 At the base of the double plate 2, one can provide openings 9 closed by valves 14 allowing a flow from the central chamber 11 to the annular chamber 3. This allows, if one reverses the direction of the pump 13, which sucks in the place of pumping, to carry out a complete emptying. These valves can be replaced by two drain holes arranged at the bottom of the tank, one in the annular zone, the other in the central zone, and connected by a tube 19 provided with a valve 15 (Figures 1 and 2). .

The emptying is carried out by the reverse rotation of the pump 13 which is simultaneous with the opening of the valve 15; the pump in this case completely empties the two areas of the tank. When the valve 15 is closed, the two zones are isolated. In addition, a drain plug 8 can provide direct draining. If it overlaps the two chambers 3 and 11, it allows rapid total emptying (Figure 2).

 The exchanger is preferably insulated at 5 as is the cover 32. It may be advantageous to provide a small access hatch 17 for example for passage of instruments, for sampling or additions of various products, and when the whole is large to form a manhole.

 It is also advantageous to provide an air vent 23, to facilitate filling.

 According to another characteristic variant of the invention, the central chamber 11 and the return pipe 12 for suction of the liquid are arranged so that the gases present in the tank, and in particular those which result, are automatically eliminated during operation of the system. fermentation and tend to form annoying mosses with liquids. To this end, the suction pipe 12 is extended towards the inside of the central chamber 11 of the tank by a pipe 24 (FIG. 5) to a level close to the cover 4, leaving a free space "e". I1 thus takes place an automatic entrainment of the residual gases trapped in the upper part of the tank, simultaneously or alternately with the liquid. cover 4 forming a baffle and forcing the liquid to descend along the plate 2. This cylinder 25, as said above, can also be constituted by one or more heat exchange plates. I1 can also be secured to the bottom 31, for example being mounted on supports such as 26, which simplifies the removal of a less bulky cover but requires that the top of the cylinder 25 be close enough to the cover 4 so that the liquid either forced to descend between cylinder 25 and plate 2 and does not pass directly from the external chamber 3 to the pipe 24, even if it means providing a seal between cylinder 25 and cover 4.

 It is understood that one can provide a series of double plates such as 2 concentric possibly separated by double plates integral with the cover and forming with those integral with the bottom a series of baffles.

 The plates fixed to the bottom can also be of different heights to ensure a cascade of runoff.

 Regarding the cover or cap 32, it can be flat, curved, ribbed, or have any suitable shape (Figure 3 for example); one can provide the seal 21 in a groove made near the upper edge of the outer wall of the tank 30. Centering pins 22 allow with the jacks such as 18 a good tightening of the seal 21. The seal 21 can still be secured to the periphery of the cover.

 Furthermore, the heat transfer fluid (expansion refrigerant gas, hot gas during heat pump operation, etc.) is introduced into the various embossed circuits of the plates such as 1 or 2.

 Connections can, as has been pointed out, be made independently, by sectors, in series, in parallel or by any combination of these means, which allows regulation and programming, in particular by changing the connections during operation or of a type from operating to another. These connections are made by tubing integral with the embossed plates not shown in the figures but which can be of any conventional type.

 In the case of programming, it can control the connections of the plates but also the flow rates and temperatures of the various fluids (to be treated and / or coolant).

 It will be noted that the valves 14 may be made of stainless steel or of a rubber membrane or any other suitable material, and arranged so that there is an opening when the emptying takes place but that they remain closed in normal operation for avoid loss of fluid.

 It is also possible to mount a pipe between 16 (inlet of the pump 13) and 7 and ensure circulation in one direction R (discharge) or the other V (drain). Cleaning is thus extremely easy and allows sterilization treatments, for example with sodium solution in wine applications. The assembly which has just been described allows very complete mixing using the pump, the soda can be introduced at 17 into the washing water supplied by the pump. The internal chamber 11 then plays the role of a sodium solution tank.

 One can provide in this chamber 11 a basket intended to accommodate the salts of tartar precipitation when the exchanger is connected to a wine tank, for clarification before bottling.

 These exchangers are also suitable for very many applications in the food or biotechnology industry for many liquids to be packaged and in particular fruit juices, wines, ciders, and others.

 In Figure 4, we find most of the elements of Figures 1 and 2 but the assembly is no longer cylindrical but frustoconical. This makes it possible to avoid the cover and possibly be limited to a manhole, which reduces the length of the seal and allows, by avoiding leaks, to work in particular at non-atmospheric pressures (high or bass).

 We have described above tanks which, of course, can be mounted by those skilled in the art in series and / or in parallel without departing from the scope of the present invention.

 This can allow in particular, in the case of programmed treatments, to work in certain cases on several different liquids and / or to be treated differently, or in others to refine the program by different exchangers.

 FIGS. 6A to F illustrate the main variations which can be conceived on the production of plates such as 1 or 2. We will first recall what has been said above. As regards the plates 1 or equivalent, they can be formed either from the wall and from one sheet or by two sheets, the assembly being preferably applied against the wall. One or two of the constituent elements of the plate are embossed to form between them at least one circuit for circulation of heat-transfer fluid (refrigerant and / or circulating).

 As regards the plates 2 or equivalent, they can be formed of two sheets either a single plate, three plates, or a double plate with circulation circuits on either side of the central plate or even of four, this which forms two plates which can optionally be thermally insulated from one another to work at different temperatures on either side.

 It will also be recalled that it is possible to envisage several series of concentric plates such as 2 or approximately concentric allowing the liquid to pass from above, which can alternate with non-exchange screens or exchange plates also concentric or approximately such, placed upwards leaving pass the liquid from below and forming baffles with the first, that is to say, forcing the liquid to pass from below.

Note also that if in Figures 1 to 5, there are shown devices -with liquids entering through the peripheral chamber. and leaving through the central chamber, we can consider a reverse or even multiple circulation: for example, in the case of three chambers (a peripheral, an average and a central with therefore two series of plates such as 2), we can do enter the liquid through the central chamber and let it out through the other two or vice versa. This can therefore be generalized in different forms with several series of concentric chambers or not
For example, we can imagine several plates - cylindrical separate or juxtaposed but included together in the same - larger peripheral chamber. We can thus produce series of plates and chambers with several inputs and / or outputs. By playing on the heights, we can also cause waterfalls of runoff.

 To come more specifically to Figures 6 they ill-ustrent, deployed flat plates such as 1 or 2.

 It will first be noted that each of the cylindrical (or all other forms) heat exchange assemblies can be constituted by one or more juxtaposed plates, circularly and / or in height. As will be seen in FIGS. 6B to 6F, the same plate can have several circulation circuits, it can therefore possibly be divided into several elementary plates each having one or more circuits.

 In addition, if the external plates (of type 1) do not anticipate special problems of arrangement and accept all circuits such as those of FIGS. 6A to F, the internal plates has three or more sheets, that is to say at least (one central and two external), can be of conformations and therefore of very different circuits from one face to the other. In the case of double plates with four sheets, the two elementary plates selected on one and the other side can be isolated, this allows totally independent circuits in their layouts on one and the other side, on the other hand, in the case of type 2 plates with three sheets, one central and two external, it is necessary to arrange the circuits on both sides so that if the heat transfer fluids are at different temperatures, exchanges between them can be avoided in the event that these are undesirable.

Figure 6A illustrates the simplest case. of a plate with a simple coil essentially vertical arrangement. Several remarks on this subject: (1) such an arrangement is easy to carry out; (2) when the plate is to be rolled into a cylinder, it is easier
that most of the circuit is placed along the generators, this
which simplifies the winding operation: indeed, when necessary
bending a plate to obtain a cylinder, a transverse channel
always risk of bending and deformation. We therefore have an interest in limiting
risks and a plate like the one in figure 6A is obviously
much more convenient to wrap around a vertical axis than around
of a horizontal axis. This is a reason why if for born
technicalities it is necessary for example to have the
spiral circuits, we can divide the plate forming the cylinder
complete in several segments. This argues in favor of provisions
prismatic since we just planar plates, but this
has angles which, even if rounded, risk accumulating
solid matter mulations.

(3) in FIG. 6A as in the following, a rectangle has been drawn
can be wound into a cylinder with vertical axis. The man of art
will deduce therefrom the shapes corresponding to trunks of cones, taken
my or pyramid trunks; (4) the inlet and outlet pipes are shown downwards, this
which is a fairly practical solution which is particularly suitable
for the use of heat transfer gases (refrigerants in particular). Indeed, it
just pierce the bottom of the tank to ensure entry and exit
But we can also go through the top, for example for
circuit layout conveniences (Figure 6F), either when you want
use the baffle plate in the high position and let it be secured
on the cover.

(5) the plates of the different walls and / or separations between the cham
bricks can be mounted independently and / or in series and / or in pa
rally. This can be easily achieved if all of the inputs and
outputs are connected from the outside in an assembly using
various manual or automatic valves. We can then program
circulation of one or more fluids at one or more temperatures
tures and the assembly of the various circuits to pass from assemblies
independent of series assemblies, parallel assemblies and / or
to all mixed edits.

 FIG. 6B represents a plate with two coils located one above the other. As seen in the descriptions of the previous figures, the liquid arrives in the tank preferably tangentially and preferably also paf the bottom. I1 will therefore circulate in a helix gradually rising to the top of the plate 2 to flow onto the other face.

It is therefore advantageous to have exchange circuits, one of which can be in contact with the liquid flow which has just entered the tank, the other with the liquid which has already undergone heat exchange with the lower circuit. In addition, it will be noted, and this is valid even for FIG. 6A or the following ones, that the rotating circulation of the liquid makes it possible to circulate the liquid to be treated and the heat-transfer fluid in the same direction or in the opposite direction. (Methodical or antimethodic exchanger)
Figure 6C privileges the exchange according to the horizontal circulation while the 6B privileges the exchange according to the vertical circulation
In fact, in FIG. 6C, two circuits are juxtaposed horizontally which allows the rotating liquid to successively meet the two circuits. We can also, as in FIG. 6D, play on the flow rates, the two circuits being nested which allows work with one or two circuits which allows to increase heat exchanges or to go from a hot circuit to a cold circuit for example. This FIG. 6D also makes it possible to imagine a double plate of type 2 with three sheets having on one face one of the circuits and on the other, the other circuit.

We can then work in different conditions by reducing the interference between the two circuits, but it is obvious that the solution with double plate four sheets with central insulator is the most effective.

 In FIG. 6E, the solutions 6B and 6C are combined, which makes it possible to play on the temperature gradients horizontally and vertically. Hence the taking into account of the helical circulation of the liquid.

In FIG. 6F, another solution is proposed which also takes account of the helical circulation, the liquid successively attacking the various circuits. This figure corresponds substantially to a circulation along approximately the slopes of one or the other of the diagonals of the rectangular plate, but one can, of course, as in the previous examples, generalize to more complex systems in their arrangements and the number of their circuits, especially with large equipment.

 To summarize, we can therefore say that the method according to the invention consists in circulating the liquid to be treated in a series of chambers of one or more tanks, chambers separated by heat exchange plates, the liquid rising in certain chambers and trickling downwards onto the faces of plates of adjoining chambers, baffles which can also be formed by plates forcing the liquid to circulate along all of the plates.

 It is therefore obvious that if FIGS. 1 to 5 represent tanks with flat bottoms, it is possible to envisage tanks with non-flat bottoms, for example descending towards the outlet (in funnels or in stairs of generally conical or pyramidal shape).

This solution has the advantage of facilitating evacuations and of providing a series of plates of which at least the upper edges are offset vertically, which facilitates successive waterfalls and runoffs. If we refer to Figure 1 for example, if the bottom is lower in the central chamber 11 than in the peripheral chamber 3, we can considerably increase the surface of the double plate 2 on the inside and therefore the heat exchange with dripping liquid. This principle can easily be generalized to several rooms and their single or double separation plates

Claims (31)

 1.- A method of heat exchange between a liquid which may contain one or more other phases such as solid materials and at least one heat transfer fluid (refrigerant or circulating) passing through at least one heat exchange circuit, characterized in that the liquid enters at least one chamber 3 defined in a tank by at least one channel plate 2 and fills the chan1bre, in heat exchange with said plates until overflowing from the top of at least one of said plates, to flow into at least one contiguous chamber 11 along the other face of said separation plate 2.  2.- Method according to claim 1, characterized by the fact that the liquid cascade from one chamber 3 to the other 11 and making heat exchange by contact with the separation plate 2 between the chambers, upstream side and by trickling against said downstream side plate.  3.- Method according to the claims 1 or 2, characterized in that the heat transfer fluid circuits provide the necessary temperature gradients along the path of the liquid (fig.6).  4.- Method according to one of claims 1 to 3, characterized in that the liquid rises helically in the chambers 3 which it fills until overflowing the top of at least one plate 2 to flow into at least one adjoining city room along the separation plate.  5.- Exchanger for the implementation of the method according to one of the preceding claims, consists of at least one enclosure in which are placed heat exchange plates 2, characterized in that said elements consist of embossed plates formed by the superposition of sheets between which the embossing provides circuits in which the fluids circulate, - (fig. 6) heat transfer fluid circulating in each of the circuits of each of the plates, the liquid being caused to circulate along the exchange surfaces of said plates.  6. Heat exchanger according to claim 5, in which aeJ different heat transfer fluids circulate in each of said circuits (FIG. 6),  7. Heat exchanger according to one of claims 5 or 6, wherein the same heat transfer fluid circulates in several of said circuits but under different physical conditions of temperature and pressure. (fig. 6).  8.- Heat exchanger according to one of claims 5 to 7, characterized in that it is generally prismatic and / or pyramidal and / or cylindrical and / or conical, (fig.4), at least uneplague d heat exchange 2 being arranged inside to provide at least one peripheral chamber 3 and at least one central chamber 11.  9. Exchanger according to claim 8, characterized in that at least one heat exchange plate 1 is arranged along the outer wall.  10.- Exchanger according to one of claims 8 or 9, characterized in that at least one heat exchange plate i form outer wall.  11.- Exchanger according to one of claims 8 to 10, characterized in that at least one peripheral chamber 3 and a central chamber 11 only communicate from above.  12.- Exchanger according to claim 11, characterized in that the arrival and withdrawal of the liquid are not the bottom (6, 12).  13.- Exchanger according to claim 11, characterized in that the liquid is drawn off in the upper part (24).  14.- Exchanger according to one of claims 11 13, characterized in that the gases are extracted in the upper part (24).  15.- Exchanger according to one of claims 8 to 14, characterized in that the elements 25disposed chicane oblige the liquid to travel the entire surface of the plates.  16.- Exchanger according to claim 15, characterized in that these baffle elements 25 are also heat exchange plates.  17.- Exchanger according to one of claims 15 or 16, characterized in that said baffled elements 25sontsolidaires uncouvercle the enclosure.  18.- Exchanger according to one of claims 8 to 17, characterized in that the exchange plates 2séparantchambèrespériphériques and central are integral with the bottom.  19.- Exchanger according to one of claims 15 to 18, characterized in that the baffle elements are integral with the bottom but kept at a distance from the latter (25, 26).  20.- Exchanger according to one of claims 8 to 19, characterized in that the top of the elements25chicanes is higher than the level of withdrawal of the liquid and / or gases.  21.- Exchanger according to one of claims 8 to 20, characterized in that at least one drain 8 is provided in the lower part of the vessel of the enclosure.  22.- Exchanger according to claim 21, characterized in that the valves 14 put the chambers in communication when the liquid circulation is reversed to ensure emptying and cleaning.  23.- Exchanger according to one of claims 8 to 22, characterized in that the upper part is provided with devices 23 for air purging.  24.- Exchanger according to one of claims 5 to 23, characterized in that the different circuits of heat transfer fluids are controlled by programs.  25.- Exchanger according to one of claims 5 to 24, characterized in that the bottom of the chambers descends from upstream to downstream, increasing the runoff height.  26.- Exchanger according to one of claims 5 to 25, characterized in that each plate defining a chamber can be decomposed into a set of contiguous elementary plates (fig 5).  27.- Exchanger according to one of claims 5 to 26, characterized in that each plate or elementary plate comprises at least one circuit (fig. 6).  28.- Exchanger according to claim 27, characterized in that the circuits can be mounted independently and / or in series and / or in parallel.  29.- Exchanger according to one of claims 5 to 28, characterized in that it is applied to the food industry.  30.- Exchanger according to one of claims 5 to 29, characterized in that it is applied to the wine industry.  31.- Exchanger according to one of claims 29 or 30, characterized in that additives can be introduced into at least one of the chambers,