FR2793167A1 - Reversible solid/gas adsorption reactor comprises electrically resistive elongated element with rectangular core and peripheral fins with spaces between them - Google Patents

Abstract

The electrical resistance (4A,4B) includes at least one electrically resistive elongated element which has a rectangular core (5A,5B) with peripheral fins (6A,6B) with spaces (7A,7B) between them for the adsorbent. The reactor for reversible solid/gas adsorption with a body (2) containing a solid adsorbent and at least one electrical resistance for regenerating the adsorbent by the Joule effect. The electrical resistance (4A,4B) includes at least one electrically resistive elongated element which has a rectangular core (5A,5B) with peripheral fins (6A,6B) with spaces (7A,7B) between them for the adsorbent. Preferred Features: At least one permeable envelope (9) surrounds the adsorbent to hold the adsorbent in contact with the electrical resistance. The body and the envelope are arranged so there is a free space (12) between them. The elongated element of the electrical resistance has at least one internal space formed longitudinally within the rectangular core and which can have a coolant passed through it. The reactor has a device for circulating coolant in the internal space. The body is made of a thermally conducting material and has thermally conducting ridges on its internal face which penetrate into the adsorbent. The reactor contains a number of units (8) each containing an electrical resistance, an adsorbent and a permeable envelope. The fins on the resistance are elongated and extend radially along the rectangular core over all its periphery. Some of the fins have branches. Alternatively the fins are in the form of discs placed transversely over the length of the core. The fins have converging or parallel faces.

Description

 The present invention relates to reactors with reversible solid / gas adsorption, as well as a regeneration resistor for the adsorbent of such a reactor.

 Reactors of this type, mainly intended for refrigeration machines, are for example known from the documents FR-A-2 693 542, FR-A-2 704 631, FR-A-2 721 696, FR-A-2 749 377 and US-A-5,333,471.

 It is known that such reactors use adsorbents, such as zeolite, to capture liquid vapor, for example water, and operate under partial pressures of between 0.5 millibar and several hundred millibars. It is also known that the adsorbents must be regenerated by heating to temperatures between 200 C and 350 C. However, these adsorbents, and in particular zeolite, are poor thermal conductors so that they cannot be regenerated quickly.

 The object of the present invention is to remedy this drawback.

 To this end, according to the invention, the reversible solid / gas adsorption reactor comprising an enclosure containing a solid adsorbent and at least one electrical resistance for the regeneration by Joule effect of said adsorbent (as for example shown by documents FR- A2 721 696 and FR-A-2 749 377) is remarkable in that said electrical resistance comprises at least one elongated electrically resistive element, constituted by an oblong core provided with peripheral fins which delimit between them spaces intended to receive said adsorbent .

 Thus, thanks to such an arrangement, the resistor has a large contact surface with the adsorbent and all of it can be located at a short distance from a portion of the resistor, so that the heating of said adsorbent is particularly effective and that the latter can be regenerated quickly.

 For this same purpose, said reactor also advantageously comprises at least one permeable envelope, for example porous or in the form of a grid, which surrounds said adsorbent so as to keep the adsorbent in contact with said electrical resistance.

 Of course, in the context of the present invention, said envelope can be in direct contact with the reactor enclosure. However, in a preferred embodiment, said enclosure and said envelope are arranged so as to form a free space between them, allowing the circulation of water vapor or gas, which in particular aims to increase! has instantaneous adsorption power of the reactor.

 Furthermore, in a particular embodiment, said elongated element of the electrical resistance has at least one internal recess made longitudinally of said oblong core and capable of being traversed by a cooling fluid, and said reactor further comprises means capable of circulating a cooling fluid in said internal recess.

Thus, said reactor can easily be cooled: either during the regeneration phase; - either during the adsorption phase, by providing an electrical sheath
trically insulating or an electrically insulating coating on the face
internal of said recess, to isolate the flow of the cooled fluid
electrical resistance.

 In addition, to promote the dissipation of thermal energy during the exothermic adsorption reaction, the reactor enclosure is made of a thermally conductive material and is provided on its internal face with thermally conductive arcs which penetrate into said sorbent ad , preferably at the level of the spaces formed between the adjacent fins.

 Furthermore, in a particular embodiment, the reactor comprises several units formed by an electrical resistance, an adsorbent and a permeable envelope, which makes it possible, depending on the number of units used, to regulate the power adsorption necessary for the application considered.

 The present invention also relates to a regeneration resistor for the adsorbent of a reversible solid / gas adsorption reactor.

 According to the invention, said regeneration resistor is remarkable in that it comprises at least one elongated electrically resistive element, constituted by an oblong core provided with peripheral fins which delimit between them spaces intended to receive said adsorbent.

 Thus, thanks to the invention and as indicated above, the regeneration resistor has a large surface area capable of coming into contact with the adsorbent, which allows particularly efficient and rapid reheating and therefore regeneration of the adsorbent.

 In the context of the present invention, the fins can have a plurality of different shapes.

 Thus, in a first preferred embodiment, the regeneration resistor comprises a plurality of generally elongated fins, arranged radially along said oblong core and distributed around its periphery, at least some of said fins being additionally provided with ramifications.

 In addition, in a second embodiment, it comprises a plurality of disc-shaped fins, arranged transversely along said oblong core.

 In addition, advantageously, said fins may have parallel or converging faces, this latter variant making it possible in particular to increase the contact surface with the adsorbent.

 Furthermore, advantageously, said elongated element has at least one internal recess made longitudinally of said oblong heart.

 The figures of the appended drawing will make it easy to understand how the invention can be implemented. In these figures, identical references designate similar elements.

 Figure 1 is a schematic perspective view of a reactor according to the invention, partially broken away.

 FIG. 2 shows, in schematic front view, a reactor such as that shown in FIG. 1.

 Figure 3 shows, in schematic front view, a reactor according to another embodiment of the invention.

 FIG. 4 schematically illustrates the regeneration resistances of a reactor according to the invention.

 Figure 5 partially shows, in perspective, a regenerative resistor such as those of Figure 4 and according to a first embodiment.

 FIG. 6 schematically illustrates a regeneration resistor according to a second embodiment.

 FIG. 7 partially shows, in perspective, the regeneration resistance of FIG. 6.

 The reactor 1 shown schematically in Figures 1 to 3 and according to the invention is a reversible solid / gas adsorption reactor.

It is part of an assembly not shown and known (for example by the documents FR-A-2 721 691 and FR-A-2 749 377 above), which is intended to adsorb water vapor or another gas , with a view to: - either producing cold, with or without an external energy supply; - or to dehydrate products, in particular agro products
food, chemical or pharmaceutical.

 In known manner, said reactor 1 comprises an enclosure 2 containing a solid adsorbent 3, for example zeolite, and at least one electrical resistance 4A, 4B for the regeneration by Joule effect of said adsorbent 3. The electrical resistance 4A, 4B is connected to a power supply unit UA, of known type, shown only in FIGS. 2 and 3 for reasons of simplification of the drawing.

 It is known that, in particular because of the reduced thermal conductivity of the adsorbent 3, the heating of the latter for its regeneration, which must be done at temperatures between 200 C and 350 C, is difficult and slow.

 To remedy this drawback, the reactor 1 according to the invention comprises at least one electrical regenerative resistance 4A, 4B comprising an elongated electrically resistive element, constituted by an oblong core 5A, 5B, provided with peripheral fins 6A, 6B which delimit between them spaces 7A, 7B intended to receive said adsorbent 3, as can be seen in FIGS. 1 to 7.

 Thus, the regeneration resistor 4A, 4B has a large contact surface with the adsorbent 3 so that all of it is located a short distance from a portion of said resistor 4A, 4B, which allows heating and therefore efficient and rapid regeneration of said adsorbent 3.

 Preferred embodiments 4A and 4B of the resistors according to the invention will be described below with reference to FIGS. 4 to 7.

The reactor 1 generally comprises at least one, but preferably a plurality of units 8 each comprising: at least one regeneration resistor; an adsorbent 3; and a permeable envelope 9, for example a porous envelope or in
form of mesh, which surrounds said adsorbent 3, as can be seen
in Figures 1 and 2.

 You can choose the number of units 8 per reactor 1, depending on the desired adsorption power.

 It will be noted that to facilitate reheating, the permeable envelope 9 of each unit 8 maintains by pressure the adsorbent 3 in contact with the electrical resistance 4A.

 The enclosure 2, preferably of parallelepipedal shape, made for example of steel, is sealed and has an opening 10 provided with a flange projection 11, to which a conduit, not shown, can be connected, for bringing in or evacuating the vapor d water or gas used.

 Of course, in particular to avoid any leakage, the sealed enclosure 2 includes a sealed and insulating seal, not shown, at the level of the passage of the resistors 4A, 4B through the wall of said enclosure 2.

 In the embodiment shown in FIGS. 1 and 2,1 'enclosure 2 and the units 8 are arranged so as to form a free space 12 between them, allowing the circulation of steam. This makes it possible to increase the instantaneous adsorption power of reactor 1.

Furthermore, in the embodiment shown in FIG. 3, this space is eliminated so that the internal face of the enclosure 2 is directly in contact: either of the sealed envelope; -or, as shown in said Figure 3, in the absence of such a
veloppe, adsorbent 3, as well as fins 6A of the resistance
4A, which promotes the dissipation of thermal energy by
generated by the exothermic adsorption reaction.

 Furthermore, in a preferred embodiment, as shown in particular in FIGS. 2 and 3, the oblong core 5A of the resistors 4A has a longitudinal internal recess 13A capable of being traversed by a cooling fluid, and the reactor 1 further comprises means 14, of known type, for example provided with a pump and capable of circulating a cooling fluid in the internal recess 13A of all (or only some of) the electrical resistors 4A of the reactor 1.

 In the examples shown (FIGS. 1 to 5 and 7), the internal recess 13A, 13B for the circulation of the cooling fluid is limited to the central axis of the oblong core 5A, 5B. However, in the case where the fins have a sufficient thickness, this recess can be widened, in an embodiment not shown, at least partially to the internal part of said thicker fins.

Thus, said reactor 1 can be easily and efficiently cooled: either during the regeneration phase; - either during the adsorption phase, by providing an electrical sheath
trically insulating 15 or an electrically insulating coating on the
internal face 16 of said recess 13A, as shown in FIG. 3,
to isolate the coolant flow from the
electrical resistance 4A.

 In addition, to promote the dissipation of the thermal energy generated during the exothermic adsorption reaction, provision may be made on the internal face 17 of the enclosure 2 of thermally conductive edges 18, preferably metallic, which penetrate into I ' adsorbent, at the spaces 7A and 7B, as can be seen in FIGS. 4 and 6, and the enclosure 2 can be made of a material which is also a good thermal conductor.

According to the invention, the reactor 1 according to the invention also has the following characteristics and / or advantages: its length and its width can be adapted to the power of ad
desired sorption; -in the embodiment of Figures 1 and 2, due to a realization
separate from enclosure 2 and units 8, reactor 1 can be made
easily bricked industrially; -due to the particular shape of the regeneration resistor 4A,
4B in accordance with the invention and specified below, the regeneration phase
tion may be limited to a few; - maintenance is non-existent; and the operation of reactor 1 is silent and is possible under a
high ambient temperature.

It is known that the operation of reactor 1 in accordance with the invention has three successive phases: an adsorption phase, during which reactor 1 is brought into contact
bran with steam (or other gas), through
the opening 10 and the duct, not shown, which is connected to it. The D
sorbent 3 then adsorbs this water vapor or gas, while remaining
killing heat which is dissipated via artes 18 and
of enclosure 2 and, where appropriate, through the re
cold 14; -a regeneration phase, during which the resistance (s) of
regeneration 4A, 4B are energized, using
the power supply unit UA so as to obtain a heater
fage at a set temperature (between 200 and 350 C) which
depends on the nature of the adsorbent 3. The latter rejects the liquid
which it contains in the form of vapor which is evacuated via the rac duct
strung at the opening 10. This vapor can then be condensed, by
example, by means of an evaporator not shown; and a cooling phase, during which the reactor is cooled
by ventilation and / or using the cooling system 14.

It will also be noted that it is possible to operate several reactors 1 in accordance with the invention: either simultaneously so as to increase the overall power of ad
sorption. Preferably, size reactors are used for this purpose.
reduced, can be industrially produced in large quantities and
therefore at reduced cost, which further reduces the cost of link-
appears to be formed by said reactors; -or alternately, so that at least one reactor 1 is
still in the adsorption phase, which provides a
continuous operation of said assembly.

 FIGS. 4 and 5 show regeneration resistors 4A produced according to a first embodiment.

 Each of these resistors 4A comprises a plurality of fins 6A of generally elongated shape, arranged radially along said oblong core 5A, being distributed around its periphery.

 In addition, some of these fins 6A are provided with ramifications 19, which makes it possible to increase the contact surface, in particular at the ends of the fins 6A, distant from the core 5A.

 To promote reheating, several 4A resistors can be brought into contact, as shown in FIG. 4. The contacting is preferably carried out by means of two fins having complementary ends, capable of fitting together. one in the other, as indicated by a reference 20 in FIG. 4. It will be noted that, in this embodiment, the maintenance of the adsorbent 3 around said resistance couple 4A is carried out, in part, by the envelope 9 and, in part, through enclosure 2.

 In another embodiment shown in FIGS. 6 and 7, the resistor 4B comprises a plurality of fins 6B in the form of a disc, arranged transversely along the oblong core 5B. These fins 6B are further arranged parallel to each other.

 By this latter embodiment, it is possible to promote the dissipation of thermal energy, by additionally providing edges 18 fixed on the internal face 17 of the enclosure 2 and penetrating respectively into the spaces 7B between the pairs of adjacent discs 6B. , until near the oblong core 5B, as can be seen in Figure 6.

It will be noted that the fins 6A, 6B can be: either fixed, in particular by welding, on the oblong core 5B, as
this is for example the case in the embodiment of FIGS. 6 and
7; - or produced, preferably by an extrusion process, in a single
part with said oblong core 5A, as for example the case
in the embodiment of Figure 5.

Claims (13)

 1. Reversible solid / gas adsorption reactor, comprising an enclosure (2) containing a solid adsorbent (3) and at least one electrical resistance (4A, 4B) for the regeneration by Joule effect of said adsorbent (3), characterized in that said electrical resistance (4A, 4B) comprises at least one elongated electrically resistive element, constituted by an oblong core (5A, 5B) provided with peripheral fins (6A, 6B) which delimit spaces (7A, 7B) between them receiving said adsorbent (3).  2. Reactor according to claim 1, characterized in that it comprises at least one permeable envelope (9) surrounding said adsorbent (3) so as to maintain by pressure the adsorbent (3) in contact with said electrical resistance ( 4A, 4B).  3. Reactor according to claim 2, characterized in that said enclosure (2) and said envelope (9) are arranged so as to form a free space (12) between them.  4. Reactor according to one of claims 1 to 3, characterized in that said elongated element of the electrical resistance (4A, 4B) has at least one internal recess (13A, 13B) formed longitudinally to said oblong core (5A, 5B) and capable of being traversed by a cooling fluid, and in that said reactor (1) further comprises means (14) capable of circulating a cooling fluid in said internal recess (13A, 13B).  5. Reactor according to any one of claims 1 to 4, characterized in that said enclosure (2) is made of a thermally conductive material and is provided on its internal face (17) with thermally conductive edges (18) which penetrate in said adsorbent (3).  6. Reactor according to any one of claims 2 to 5, characterized in that it comprises several units (8) formed of an electrical resistance (4A), an adsorbent (3) and a permeable envelope ( 9).  7. Regeneration resistance for the adsorbent of a reversible solid / gas adsorption reactor, characterized in that it comprises at least one elongated element (4A, 4B) electrically resistive, constituted by an oblong core (5A, 5B) provided with peripheral fins (6A, 6B) which delimit between them spaces (7A, 7B) intended to receive said adsorbent (3).  8. Resistor according to claim 7, characterized in that it comprises a plurality of fins (6A) of generally elongated shape, arranged radially along said oblong core and distributed around its periphery.  9. Resistor according to claim 8, characterized in that at least some of said fins (6A) are provided with branches (19).  10. Resistor according to claim 7, characterized in that it comprises a plurality of fins (6B) in the form of a disc, arranged transversely along the said oblong core (5B).  11. Resistor according to any one of claims 7 to 10, characterized in that said fins (6A) have converging faces.  12. Resistor according to any one of claims 7 to 10, characterized in that said fins (5A) have parasitic faces.  13. Resistor according to any one of claims 7 to 11, characterized in that said elongated element (4A, 4B) has at least one internal recess (13A, 13B) formed longitudinally to said oblong core (5A, 5B).