EP0082092B1 - Process and device for heating a dielectric or nearly dielectric liquid, and use of this device for heating, in particular of a calorific fluid - Google Patents

Process and device for heating a dielectric or nearly dielectric liquid, and use of this device for heating, in particular of a calorific fluid Download PDF

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Publication number
EP0082092B1
EP0082092B1 EP82420166A EP82420166A EP0082092B1 EP 0082092 B1 EP0082092 B1 EP 0082092B1 EP 82420166 A EP82420166 A EP 82420166A EP 82420166 A EP82420166 A EP 82420166A EP 0082092 B1 EP0082092 B1 EP 0082092B1
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EP
European Patent Office
Prior art keywords
resistors
liquid
heating
resistor
enclosure
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Expired
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EP82420166A
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German (de)
French (fr)
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EP0082092A1 (en
Inventor
François Giolito
François Vachet
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Monsanto Co
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Rhone Poulenc Chimie SA
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Priority to AT82420166T priority Critical patent/ATE32643T1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/10—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium
    • F24H1/101—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium using electric energy supply
    • F24H1/102—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium using electric energy supply with resistance
    • F24H1/103—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium using electric energy supply with resistance with bare resistances in direct contact with the fluid
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/78—Heating arrangements specially adapted for immersion heating
    • H05B3/82—Fixedly-mounted immersion heaters

Definitions

  • the present invention relates to a method of heating a dielectric or substantially dielectric product using electrical energy. It also relates to a heating appliance implementing said method, and the use of such an appliance.
  • the "product" as defined above can be present before heating both in the liquid state and in the solid state, a product in the solid state being able to pass into the liquid state under the effect of heat.
  • the "product" can of course consist of a single phase or of several phases, it can for example be in the form of a gas / solid, liquid / liquid or even solid / liquid mixture.
  • the method and apparatus, objects of the present invention are more particularly intended for the heating of heat transfer fluids.
  • German Patent No. 2,400,470 describes an instantaneous electric water heater comprising, inside an insulating block, a water circulation channel in which three resistors are placed directly; a sophisticated tension regulation system is provided to avoid scaling. Such a device cannot be used in the presence of a dielectric liquid because it would burn by fusion of the electrical resistances.
  • French Patent No. 1,600,146 relates to a hot air heating installation using an expanded metal resistance; a liquid can be injected downstream of the resistance in order to humidify the air.
  • liquids are usually heated by means of a heating device comprising at least one electrical resistance located in a metal sheath, an electrical insulation means such as air, magnesia, boron nitride, etc. being provided between the resistance and the inner surface of the sheath, the device being immersed in the sen of the liquid to be heated.
  • a heating device comprising at least one electrical resistance located in a metal sheath, an electrical insulation means such as air, magnesia, boron nitride, etc. being provided between the resistance and the inner surface of the sheath, the device being immersed in the sen of the liquid to be heated.
  • the heating device comprises a bundle of sheathed resistances in the shape of a U fixed by their free arms to a plate through which the electrical connections of each U-shaped resistance are ensured.
  • the plate also makes it possible to fix the heating device to a flange surrounding an opening of the enclosure containing the liquid to be heated, this opening also makes it possible to introduce the bundle inside the enclosure.
  • the geometry of the resistance bundle is the cause of significant pressure drops, areas of liquid stagnation and therefore overheating and risks of degradation thereof. In addition, this geometry also promotes fouling of the beam.
  • each U-shaped resistor implies being electrically connected at each of its ends.
  • This is a major drawback of this heating method since there are practically no beams on the market with an available unit power greater than 200 kW, which means providing the enclosure containing the liquid to be heated with a large number of beams to have the necessary power.
  • this mode of heating involves bulky and expensive material.
  • the resistance is bare, that is to say that between the resistance and the product there are no substantial means of electrical insulation, this does not exclude that in certain cases , and for some applications, the resistance includes a thin coating.
  • the process, object of the invention is such that a potential difference greater than 380 V can be applied across the resistance (s).
  • resistance means a conductor in which all the electrical energy received is transformed into heat by the Joule effect.
  • a device has also been found for heating a dielectric liquid with a resistivity greater than 10 8 52 / cm which implements the heating method, object of the invention.
  • Such a heating device is characterized in that it comprises an enclosure containing said liquid in which is immersed, at least one naked resistance in the form of a plate, said one or said resistors in the form of a plate being placed in such a way that the speed vectors of the general movement of the liquid in natural or forced flow, in the vicinity of the resistor (s) being tangent or parallel to the faces of said plates, and means for connecting the resistor (s) to an electrical distribution network.
  • the heating device object of the invention, comprises several resistors electrically connected in series and / or in parallel.
  • the device according to the invention can comprise at least three resistors electrically connected in a triangle or in a star. This embodiment makes it possible to connect the resistors to a three-phase electrical distribution network.
  • resistance in the present text designates both a single resistance and a resistance formed by several elementary resistances, identical or not, connected in series and / or in parallel.
  • the apparatus for heating a dielectric or substantially dielectric product, object of the invention can be such that the enclosure containing the product is swept by the product to be heated.
  • the enclosure of the appliance can be a section of pipe swept by the product to be heated.
  • Such an apparatus is more particularly intended for maintaining the temperature of a product in motion by compensating for the thermal losses which have occurred, for example during the transport of the hot product over long distances.
  • the enclosure, swept by the product to be heated, of such an apparatus can also be for example the reaction zone of a chemical reactor, the heat necessary for the reaction being directly supplied to the reaction mixture by one or more resistors immersed in this one.
  • the enclosure swept by the product can be the reaction zone of a fluidized bed reactor, the resistors being immersed directly in the gas / solid mixture.
  • enclosure swept by the product is meant above that the flow rate of the product by current the enclosure is relatively large compared to the volume of product present in the enclosure.
  • the enclosure of a heating device according to the invention can be constituted by a container comprising means for entering the product to be heated and means for leaving the hot product.
  • a container comprising means for entering the product to be heated and means for leaving the hot product.
  • Such an apparatus may include a container of sufficient volume to constitute a storage of hot product.
  • the boilers are heating devices according to this embodiment. Such heaters are more particularly intended for heating organic, natural or synthetic heat transfer fluids, used in industrial installations. It is also possible to use as heat transfer fluid products or mixtures of substantially dielectric molten mineral products.
  • the enclosure can be constituted by a closed container which comprises means for filling and draining the product, at least one resistance being immersed in the product.
  • a closed container which comprises means for filling and draining the product, at least one resistance being immersed in the product.
  • the enclosure of a heating device object of the invention can be constituted by a container comprising means for entering the product to be heated and means for leaving the vapor of said product.
  • a container comprising means for entering the product to be heated and means for leaving the vapor of said product.
  • an apparatus according to this embodiment is intended for heating a liquid, the liquid being heated to its boiling point in the container.
  • the boilers are heating devices according to this other embodiment.
  • the general movement of the product is the movement of the product corresponding to the movement thereof, without taking into account local movements, such as vortices, in the vicinity of the faces of the plates.
  • the purpose of this arrangement is to reduce as much as possible the pressure losses due to the resistances and thus to promote thermal exchanges with the product while maintaining high scanning speeds of the faces of the resistances by the product.
  • plate more precisely designates a sheet of a rigid, flat and not very thick material, the meaning of this term will be extended in the present text to thin sheets which are not planar, for example cylindrical or left.
  • Resistors in the form of left plates will be placed in such a way that the velocity vectors of the general movement of the product, in natural or forced flow, in the vicinity of the resistances, are tangent to the faces of said plates.
  • Resistors in the form of flat plates will be placed in such a way that the velocity vectors of the general movement of the product in natural or forced flow, in the vicinity of said surfaces, are parallel to the faces of the plates.
  • heating devices having a natural or forced flow of the product, of general direction parallel to a given direction, it is possible to use resistors in the form of a substantially flat plate placed parallel to the general direction of movement of the product.
  • Resistors in the form of an elongated rectangular flat plate can be folded, for example in a zigzag, according to their length and placed in such a way that their width is parallel to the general direction of movement of the product.
  • plate-shaped resistors of generally cylindrical shape the cylinder being generated by a generator moving parallel to the general direction of movement of the product by resting on a director, open or closed, of curved shape, by circular example, or polygonal, several cylindrical resistors can be placed concentrically.
  • the resistors can be in the form of a plate of continuous structure or of discontinuous structure.
  • continuous structure of plate-shaped resistors is meant that the structure of the resistors does not have a hole, thus resistors of continuous structure are similar to sheets.
  • discontinuous structure of resistors in the form of a plate is meant that the structure of the resistors has holes, thus resistors of discontinuous structure can be made of a fabric obtained by weaving, knitting, braiding or twisting. They can also consist of a perforated sheet obtained by cutting with removal of material, for example by punching.
  • Preferably plate-shaped resistors of discontinuous structure are obtained by cutting a plurality of slots in a sheet and stretching in a direction perpendicular to the slots.
  • the face of the plates is the surface which envelops the reliefs of the plates.
  • the resistors are made of materials, resistant to corrosion.
  • the resistors can be made of stainless steels of nuances usually used for this type of material, in refractory stainless steels, special steels can also be used after they have undergone an anticorrosion treatment.
  • the surfaces of the resistors can be of substantially smooth appearance, preferably they are of rough appearance. This rough appearance can be obtained for example by sanding.
  • Resistors whose surfaces are rough in appearance are more particularly intended for the production of heating devices objects of the invention which comprise means for entering a liquid to be heated and means for leaving the vapor of said liquid .
  • the roughness of the resistors promotes the nucleated boiling of the liquid.
  • the surfaces of the resistors may be provided with a coating, this coating may be porous, in order to promote nucleated boiling, it may also be a thin anti-corrosion coating, for example made of silicone enamel or thermostable.
  • the apparatus for heating a dielectric or practically dielectric product, according to the invention can be used in particular for heating chemicals with little or no conductivity of electricity, used in industrial processes.
  • This heater is particularly intended for heating heat transfer fluids used in chemical installations.
  • the heater (1) object of the invention, shown schematically in Figure 1, is more particularly a heater for heat transfer fluid used in an industrial installation.
  • This heating device (1) comprises an enclosure (2) containing the heat transfer fluid (3), in the heat transfer fluid (3) are immersed six resistors (4) and means (5) for connecting the resistors (4) to a electrical distribution network (6).
  • the enclosure (2) is, according to the present embodiment, a container formed by a body (7) substantially cylindrical, closed at its ends by a cover (8) and a bottom (9).
  • the enclosure (2) comprises at its lower part inlet means (10) of the heat transfer fluid to be heated and in the vicinity of its upper part outlet means (11) of hot heat transfer fluid, these means consist of pipes .
  • the inlet pipe (10) is preferably provided with a three-way valve (12) allowing the emptying of the heating appliance (1
  • Resistors (4) are in the form of substantially rectangular flat plates, their faces are placed parallel to the general direction of movement of the fluid in the heater, upward movement represented by the arrow F. They are held in place using insulating supports (14) fixed to the body (7) of the enclosure (2).
  • the six resistors (4) are connected to each other in series by conductive bars (15), the two extreme resistors include the means (5) for connecting the assembly to the electrical distribution network (6).
  • the connections between the resistors (4) and the electrical network (6) pass through the bottom (9) of the enclosure (2) through an opening (16) provided with means of electrical insulation (17) and sealing.
  • resistors (4) and their mode of electrical connection have only been described above by way of example and it is not going beyond the ambit of the invention to replace at least one resistance (4) with several elementary resistances and / or by establishing the electrical connections between them differently.
  • the enclosure (2) is not completely filled with heat transfer fluid (3), in the free space (18) between the surface of the heat transfer fluid (3) and the cover (8) of the enclosure, a nitrogen pressure, the cover (8) being provided with a tube (19) for this purpose.
  • connections between the resistors (4) and the electrical network (6) can also be carried out through an opening of the cover (8), in the area of the cover (8) not bathed by the heat transfer fluid.
  • the inlet pipes (10) of the heat transfer fluid to be heated and the outlet (11) of hot heat transfer fluid can be connected directly to the circuit for implementing the hot fluid, that is to say to the circuit for heating the industrial installation.
  • the inlet pipes (10) of the heat transfer fluid to be heated and of the outlet (11) of the hot heat transfer fluid can be connected to a heat exchanger in which another heat transfer fluid is heated, this being used in the circuit for heating the industrial installation.
  • the resistors (4) can be produced in the form of substantially flat plates of discontinuous structure as shown in partial views in FIGS. 2 and 3.
  • the plate-shaped resistor of discontinuous structure a fragment of which is represented in FIG. 2, comprises holes (19) substantially in the form of a diamond obtained by cutting from a sheet of metal a plurality of slots aligned along their length and placed in staggered rows, then stretching in a direction perpendicular to the slits, that is to say parallel to the small diagonals of the diamonds. This stretching causes a rotation of the ribbons (20) separating the diamonds (cf. FIG. 3).
  • the faces of the plates are the surfaces, materialized by the two broken lines (21, 22), which envelop all the reliefs of the plates.
  • FIG. 3 shows the speed vectors V of the general movement of the flowing heat transfer fluid
  • the speed vectors V are here parallel to the faces of the plate, this general movement does not take account of local movements, such as the vortices T, created by the reliefs of the discontinuous structure plate. These T vortices favor the transfer of heat between the resistance and the heat transfer fluid.
  • the electrical resistance (s) being immersed directly in the dielectric or practically dielectric product allow better heat exchange because, with the heating method according to the invention, the surface which participates in the heat exchange with the product to be heated is the very surface through which the Joule effect born in resistance dissipates.
  • the entire surface of the resistor participates in the exchange with the product and the temperature difference between the resistor and the product is small, which limits the risks of thermal degradation of the product which is directly in contact with the resistor.
  • the method and the heating device according to the invention also have the advantage of allowing the construction of compact heating devices, in particular boilers.
  • Another advantage of the heating appliances which are the subject of the invention is that, by the shape of the resistors and by their positioning in such a way that the velocity vectors of the general movement of the product in the vicinity of the resistors are tangent or parallel to the faces of the plates, the pressure drops of the product in the heater are relatively low. These relatively low pressure drops for an appliance intended for heating a liquid product often allow thermosyphon operation of the appliance or, failing this, assisted circulation of the liquid, without requiring the use of powerful pumping means. In addition, when such a heater is used as a boiler, it allows a free passage section for large bubbles, unlike the boilers according to the prior art.
  • the heaters according to the invention are easy to build and maintain, the sealing problems at the resistance sheaths being very limited.
  • a substantially parallelepipedal boiler It consists of a container surmounted by an air exchanger.
  • the container is made of partially insulated sheet metal to ensure, taking into account the regulation system, almost permanent heating operation.
  • It has three resistors, connected in series, in the form of an elongated rectangular plate, zigzag folded along their length, and located at different levels parallel to the bottom of the boiler.
  • the resistors are plates of discontinuous structure as shown in Figure 2, they dissipate a power of 2 kW.
  • the boiler is equipped with temperature measurement probes placed above and below the resistors.
  • the boiler contains 30 liters of heat transfer fluid consisting of partially hydrogenated polyphenyls, marketed under the name of GILOTHERM TH by the company RHONE-POULENC SPECIALITES CHIMIQUES.
  • the boiler operated as a thermosyphon boiler.
  • the average exchange coefficient was 700 W / m2 ° C and the temperature difference between the surface of the resistor and the GILOTHERM TH in boiling range of around 24 ° C.
  • a parallelepipedal boiler was produced having a resistance capable of dissipating 250 W.
  • a mixture of terphenyls consisting of 12% orthoterphenyl, 60% metaterphenyl, 28% paraterphenyl, was introduced into the boiler container. final melting point of 150 ° C., marketed under the name of OMP terphenyls by the company RHONE-POULENC SPECIALITES CHEMIQUES.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Thermal Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Resistance Heating (AREA)
  • Instantaneous Water Boilers, Portable Hot-Water Supply Apparatuses, And Control Of Portable Hot-Water Supply Apparatuses (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Forging (AREA)
  • Mounting, Exchange, And Manufacturing Of Dies (AREA)
  • Heat-Pump Type And Storage Water Heaters (AREA)

Abstract

1. Process for heating a dielectric liquid consisting in immersing at least one bare resistor, to the terminals of which a potential difference is applied, directly in the said liquid contained in an enclosure, characterized in that for heating a liquid with a resistivity higher than 10**8 OMEGA /cm the liquid is conducted along plate-shaped resistors so that the velocity vectors of the general motion of the liquid under natural or forced flow, in the vicinity of the resistor or resistors are tangent or parallel to the faces of the said plates.

Description

La présente invention concerne un procédé de chauffage d'un produit diélectrique ou pratiquement diélectrique à l'aide d'énergie électrique. Elle concerne également un appareil de chauf- frage mettant en oeuvre ledit procédé, et l'emploi d'un tel appareil.The present invention relates to a method of heating a dielectric or substantially dielectric product using electrical energy. It also relates to a heating appliance implementing said method, and the use of such an appliance.

Dans le présent texte le terme "produit" désignera au sens chimique du terme aussi bien un produit chimique unique qu'un mélange de deux ou plusieurs produits chimiques.In the present text the term "product" will mean in the chemical sense of the term both a single chemical and a mixture of two or more chemicals.

Le "produit" tel que défini ci-avant peut se présenter avant chauffage aussi bien à l'état liquide qu'à l'état solide, un produit se présentant à l'état solide pouvant passer à l'état liquide sous l'effet d'un apport de chaleur.The "product" as defined above can be present before heating both in the liquid state and in the solid state, a product in the solid state being able to pass into the liquid state under the effect of heat.

Le "produit" peut bien sûr être constitué d'une seule phase ou de plusieurs phases, il peut par exemple se présenter sous former d'un mélange gaz/solide, liquide/liquide ou encore solide/ liquide.The "product" can of course consist of a single phase or of several phases, it can for example be in the form of a gas / solid, liquid / liquid or even solid / liquid mixture.

Le procédé et l'appareil, objets de la présente invention, sont plus particulièrement destinés au chauffage de fluides caloporteurs.The method and apparatus, objects of the present invention, are more particularly intended for the heating of heat transfer fluids.

Le brevet allemand no 2.400.470 décrit un chauffe-eau électrique instantané comportant à l'intérieur d'un bloc isolant un canal de circulation d'eau dans lequel sont placées directement trois résistances; un système sophistiqué de régulation de tension est prévu afin d'en éviter l'entartrage. Un tel dispositif ne peut être utilisé en présence d'un liquide diélectrique car il brûlerait par fusion des résistances électriques.German Patent No. 2,400,470 describes an instantaneous electric water heater comprising, inside an insulating block, a water circulation channel in which three resistors are placed directly; a sophisticated tension regulation system is provided to avoid scaling. Such a device cannot be used in the presence of a dielectric liquid because it would burn by fusion of the electrical resistances.

Le brevet français no 1.600.146 vise une installation de chauffage à air chaud à l'aide d'une résistance en métal déployé; un liquide peut être injecté en aval de la résistance dans le but d'humidifier l'air.French Patent No. 1,600,146 relates to a hot air heating installation using an expanded metal resistance; a liquid can be injected downstream of the resistance in order to humidify the air.

Les techniques de chauffage de produits à l'aide d'énergie électrique au moyen de l'effet Joule, actuellement utilisées industriellement, sont identiques que le produit à chauffer soit diélectrique ou conducteur. Ainsi par exemple, les liquides sont habituellement, chauffés au moyen de dispositif de chauffage comportant au moins une résistance électrique située dans une gaine métallique, un moyen d'isolation électrique tel que air, magnésie, nitrure de bore, ... étant prévu entre la résistance et la surface intérieure de la gaine, le dispositif étant immergé au sen du liquide à chauffer.The techniques for heating products using electrical energy by means of the Joule effect, currently used industrially, are identical whether the product to be heated is dielectric or conductive. Thus, for example, liquids are usually heated by means of a heating device comprising at least one electrical resistance located in a metal sheath, an electrical insulation means such as air, magnesia, boron nitride, etc. being provided between the resistance and the inner surface of the sheath, the device being immersed in the sen of the liquid to be heated.

La plus souvent, afin de pouvoir disposer d'une puissance suffisante, le dispositif de chauffage comport un faisceau de résistances gainées en forme de U fixées par leurs bras libres à une plaque à travers laquelle les connexions électriques de chaque résistance en U sont assurées. La plaque permet également la fixation du dispositif de chauffage à une bride entourant une ouverture de l'enceinte contenant le liquide à chauffer, cette ouverture permet aussi d'introduire le faisceau à l'intérieur de l'enceinte.Most often, in order to be able to have sufficient power, the heating device comprises a bundle of sheathed resistances in the shape of a U fixed by their free arms to a plate through which the electrical connections of each U-shaped resistance are ensured. The plate also makes it possible to fix the heating device to a flange surrounding an opening of the enclosure containing the liquid to be heated, this opening also makes it possible to introduce the bundle inside the enclosure.

Bien que ce mode de chauffage donne satisfaction, il présente de nomoreux inconvénients.Although this method of heating is satisfactory, it has numerous drawbacks.

En effet, comme des moyens d'isolation électrique sont nécessairement placés entre la résistance et la gaine métallique, ces moyens étant aussi, généralement, des isolants thermiques, il apparaît une différence de température importante entre la résistance elle même et la surface de la gaine participant aux échanges thermiques avec le liquide à chauffer.Indeed, as electrical insulation means are necessarily placed between the resistor and the metal sheath, these means also being, generally, thermal insulators, there appears to be a significant difference in temperature between the resistor itself and the surface of the sheath. participating in thermal exchanges with the liquid to be heated.

De plus, la géométrie du faisceau de résistances est cause de pertes de charges importantes, de zones de stagnation du liquide donc de surchauffes et de risques de dégradations de celui-ci. En outre, cette géométrie favorise aussi l'encrassement du faisceau.In addition, the geometry of the resistance bundle is the cause of significant pressure drops, areas of liquid stagnation and therefore overheating and risks of degradation thereof. In addition, this geometry also promotes fouling of the beam.

De par leur conception, les faisceaux sont lourds et encombrants et de plus, chaque résistance en U implique d'être connectée électriquement à chacune de ses extrémités. Ceci est un inconvénient important de ce mode de chauffage, car on ne dispose pratiquement pas sur le marché de faisceaux d'une puissance unitaire disponible supérieure à 200 kW, ce qui implique de pourvoir l'enceinte contenant le liquide à chauffer d'un grand nombre de faisceaux pour disposer de la puissance nécessaire. Ainsi, lorsque des volumes ou des débits importants de liquide sont à chauffer, à des températures de l'ordre de 300°C par exemple, dans des installations de produits chimiques, ce mode de chauffage implique un maté- rial encombrant et coûteux.By their design, the beams are heavy and bulky and moreover, each U-shaped resistor implies being electrically connected at each of its ends. This is a major drawback of this heating method, since there are practically no beams on the market with an available unit power greater than 200 kW, which means providing the enclosure containing the liquid to be heated with a large number of beams to have the necessary power. Thus, when large volumes or flow rates of liquid are to be heated, at temperatures of the order of 300 ° C. for example, in chemical installations, this mode of heating involves bulky and expensive material.

Pour pallier ces inconvénients pour le chauffage de produits diélectriques ou pratiquement diélectriques à l'aide d'énergie électrique on a maintenant mis au point un procédé de chauffage et réalisé un appareil mettant en oeuvre lëdit procédé.To overcome these drawbacks for the heating of dielectric or practically dielectric products using electrical energy, a heating process has now been developed and an apparatus is implemented implementing said process.

Il a maintenant été trouvé un procédé de chauffage d'un liquide, diélectrique consistant à immerger directement dans ledit liquide contenu dans une enceinte au moins une résistance nue aux bornes de laquelle on applique une différence - de potential, caractérisé en ce que pour le chauffage d'un liquide d'une résistivité supérieure à 10'n/cm le liquide est conduit le long de résistances en forme de plaques de façon telle que les vecteurs vitesses du mouvement général du liquide en écoulement naturel ou forcé, au voisinage de la ou des résistances sont tangents ou parallèles aux faces desdites plaques.We have now found a method of heating a liquid, dielectric consisting in immersing directly in said liquid contained in an enclosure at least one naked resistance at the terminals of which a difference - of potential is applied, characterized in that for heating of a liquid with a resistivity greater than 10'n / cm the liquid is led along resistors in the form of plates in such a way that the velocity vectors of the general movement of the liquid in natural or forced flow, in the vicinity of the or resistors are tangent or parallel to the faces of said plates.

Par "directement" on entend que la résistance est nue, c'est-à-dire qu'entre la resistance et le produit il n'existe pas de moyens substantiels d'isolation électrique, ceci n'exclut pas, que dans certains cas, et pour certaines applications, la résistance comporte un mince revêtement.By "directly" is meant that the resistance is bare, that is to say that between the resistance and the product there are no substantial means of electrical insulation, this does not exclude that in certain cases , and for some applications, the resistance includes a thin coating.

Le procédé, object de l'invention, est tel que l'on peut appliquer aux bornes de la ou des résistances une différence de potential supérieure à 380 V.The process, object of the invention, is such that a potential difference greater than 380 V can be applied across the resistance (s).

On peut notamment appliquer aux bornes de la résistance des différences de potential allant jusqu'a 10 000 V, des différences de potential de l'ordre de 5 500 V étant couramment disponibles en usine. Bien sûr, dans ce cas, lors de la mise en oeuvre du procédé, l'homme de l'art se conformera aux règles en vigueur et aux spécifications particulières de conception et d'utilisation des installations haute tension.It is possible in particular to apply across the resistance limits potential differences of up to 10,000 V, potential differences of the order of 5,500 V being commonly available in the factory. Of course, in this case, during the implementation of the method, the skilled person complies will follow the rules in force and the specific specifications for the design and use of high-voltage installations.

Dans le présent texte par "résistance" on entend un conducteur dans lequel toute l'énergie électrique reçue est transformée en chaleur par effet Joule.In the present text, "resistance" means a conductor in which all the electrical energy received is transformed into heat by the Joule effect.

Il a également été trouvé un appareil de chauffage d'un liquide diélectrique de résistivité supérieure à 10852/cm qui met en oeuvre le procédé de chauffage, object de l'invention.A device has also been found for heating a dielectric liquid with a resistivity greater than 10 8 52 / cm which implements the heating method, object of the invention.

Un tel appareil de chauffage est caractérisé en ce qu'il comporte une enceinte contenant ledit liquide dans lequel est immergée, au moins une résistance nue en forme de plaque, ladite ou lesdites résistances en forme de plaque étant placées de façon telle que les vecteurs vitesses du mouvement général du liquide en écoulement naturel ou forcé, au voisinage de la ou des résistances soient tangents ou parallèles aux faces desdites plaques, et des moyens pour relier la ou lesdites résistances à un réseau de distribution électrique.Such a heating device is characterized in that it comprises an enclosure containing said liquid in which is immersed, at least one naked resistance in the form of a plate, said one or said resistors in the form of a plate being placed in such a way that the speed vectors of the general movement of the liquid in natural or forced flow, in the vicinity of the resistor (s) being tangent or parallel to the faces of said plates, and means for connecting the resistor (s) to an electrical distribution network.

Avantageusement, l'appareil de chauffage, object de l'invention, comporte plusieurs résistances reliées électriquement en série et/ou en parallèle.Advantageously, the heating device, object of the invention, comprises several resistors electrically connected in series and / or in parallel.

Selon un mode de réalisation, l'appareil, selon l'invention, peut comporter au moins trois résistances reliées électriquement en triangle ou en étoile. Ce mode de réalisation permet de relier les résistances à un réseau de distribution électrique triphasé.According to one embodiment, the device according to the invention can comprise at least three resistors electrically connected in a triangle or in a star. This embodiment makes it possible to connect the resistors to a three-phase electrical distribution network.

Le terme "résistance" dans le présente texte désigne aussi bien une résistance unique qu'une résistance formée de plusieurs résistances élémentaires, identiques ou non, reliées en série et/ ou en parallèle.The term "resistance" in the present text designates both a single resistance and a resistance formed by several elementary resistances, identical or not, connected in series and / or in parallel.

L'homme de l'art déterminera le schéma électrique de liaison des résistances, selon la puissance de chauffage nécessaire, le matériel disponible, les impératifs de construction ....Those skilled in the art will determine the electrical connection diagram of the resistors, according to the heating power required, the equipment available, the construction requirements ...

L'appareil de chauffage d'un produit diélectrique ou pratiquement diélectrique, objet de l'invention, peut être tel que l'enceinte contenant le produit est balayée par le produit à chauffer.The apparatus for heating a dielectric or substantially dielectric product, object of the invention, can be such that the enclosure containing the product is swept by the product to be heated.

L'enceinte de l'appareil peut être un tronçon de conduite balayé par le produit à chauffer. Un tel appareil est plus particulièrement destiné à maintenir la température d'u'n produit en mouvement par compensation des pertes thermiques survenues par exemple lors du transport du produit chaud sur de longues distances.The enclosure of the appliance can be a section of pipe swept by the product to be heated. Such an apparatus is more particularly intended for maintaining the temperature of a product in motion by compensating for the thermal losses which have occurred, for example during the transport of the hot product over long distances.

L'enceinte, balayée par le produit à chauffer, d'un tel appareil peut aussi être par exemple la zone de réaction d'un réacteur chimique, la chaleur nécessaire à la réaction étant directement apportée au mélange réactionnel par une ou plusieurs résistances immergées dans celui-ci. Ainsi l'enceinte balayée par le produit peut être la zone de réaction d'un réacteur à lit fluidisé, les résistances étant immergées directement dans le mélange gaz/solide.The enclosure, swept by the product to be heated, of such an apparatus can also be for example the reaction zone of a chemical reactor, the heat necessary for the reaction being directly supplied to the reaction mixture by one or more resistors immersed in this one. Thus the enclosure swept by the product can be the reaction zone of a fluidized bed reactor, the resistors being immersed directly in the gas / solid mixture.

Par "enceinte balayée par le produit" on entend ci-avant que le débit du produit par courant l'enceinte est relativement important par rapport au volume de produit présent dans l'enceinte.By "enclosure swept by the product" is meant above that the flow rate of the product by current the enclosure is relatively large compared to the volume of product present in the enclosure.

Au contraire, si après quand l'enceionte est un "récipient comportant des moyens d'entrée et des moyens de sortie" on entend que celle-ci contient un certain volume de produit et que le débit de produit parcourant l'enceinte est faible vis-à-vis du produit présent dans celle-ci.On the contrary, if after when the enclosure is a "container comprising inlet means and outlet means" it is understood that the latter contains a certain volume of product and that the flow of product passing through the enclosure is low. -to the product present therein.

Selon un autre mode de réalisation, l'enceinte d'un appareil de chauffage selon l'invention peut être constituée par un récipient comportant des moyens d'entrée du produit à chauffer et des moyens de sortie du produit chaud. Un tel appareil peut comporter un récipient d'un volume suffisant pour constituer un stockage de produit chaud.According to another embodiment, the enclosure of a heating device according to the invention can be constituted by a container comprising means for entering the product to be heated and means for leaving the hot product. Such an apparatus may include a container of sufficient volume to constitute a storage of hot product.

Les chaudières sont des appareils de chauffage selon ce mode de réalisation. De tels appareils de chauffage sont plus particulièrement destinés au chauffage de fluides caloporteurs organiques, naturels ou synthétiques, utilisés dans les installations industrielles. On peut aussi utiliser comme fluide caloporteur des produits ou des mélanges de produits minéraux fondus pratiquement diélectriques.The boilers are heating devices according to this embodiment. Such heaters are more particularly intended for heating organic, natural or synthetic heat transfer fluids, used in industrial installations. It is also possible to use as heat transfer fluid products or mixtures of substantially dielectric molten mineral products.

Selon un autre mode de réalisation, l'enceinte peut être constituée par un récipient fermé qui comporte des moyens de remplissage et de vidange du produit au moins une résistance étant immergée dans le produit. Un tel appareil permet de recevoir de la chaleur, de la stocker et de la restituer.According to another embodiment, the enclosure can be constituted by a closed container which comprises means for filling and draining the product, at least one resistance being immersed in the product. Such an apparatus makes it possible to receive heat, to store it and to restore it.

Selon encore un autre mode de réalisation, l'enceinte d'un appareil de chauffage object de l'invention peut être constitué par un récipient comportant des moyens d'entrée du produit à chauffer et des moyens de sortie de la vapeur dudit produit. De préférence un appareil selon ce mode de réalisation est destiné à chauffer un liquide, le liquide étant chauffé jusqu'à son point d'ebullition dans le récipient.According to yet another embodiment, the enclosure of a heating device object of the invention can be constituted by a container comprising means for entering the product to be heated and means for leaving the vapor of said product. Preferably an apparatus according to this embodiment is intended for heating a liquid, the liquid being heated to its boiling point in the container.

Les bouilleurs sont des appareils de chauffage selon cet autre mode de réalisation.The boilers are heating devices according to this other embodiment.

Le mouvement général du produit est le mouvement du produit correspondant au déplacement de celui-ci, sans tenir compte de mouvements locaux, tels que les tourbillons, au voisinage des faces des plaques.The general movement of the product is the movement of the product corresponding to the movement thereof, without taking into account local movements, such as vortices, in the vicinity of the faces of the plates.

Cette disposition a pour but de diminuer autant que possible les pertes de charges dues aux résistances et ainsi de favoriser les échanges thermiques avec le produit en conservant des vitesses de balayage des faces des résistances par le produit, élevées.The purpose of this arrangement is to reduce as much as possible the pressure losses due to the resistances and thus to promote thermal exchanges with the product while maintaining high scanning speeds of the faces of the resistances by the product.

Bien que le terme "plaque" désigne plus précisément une feuille d'une matière rigide, plane et peu épaisse, on étendra dans le présent texte la signification de ce terme à des feuilles peu épaisses non planes, par exemple cylindriques ou gauches.Although the term "plate" more precisely designates a sheet of a rigid, flat and not very thick material, the meaning of this term will be extended in the present text to thin sheets which are not planar, for example cylindrical or left.

Des résistances en forme de plaques gauches seront plaçées de façon telle que les vecteurs vitesses du mouvement général du produit, en écoulement natural ou forcé, au voisinage des résistances, soient tangents aux faces desdites plaques.Resistors in the form of left plates will be placed in such a way that the velocity vectors of the general movement of the product, in natural or forced flow, in the vicinity of the resistances, are tangent to the faces of said plates.

Des résistances en forme de plaque planes seront placées de façon telle que les vecteurs vitesses du mouvement général du produit en écoulement naturel ou forcé, au voisinage desdites surfaces, soient parallèles aux faces des plaques.Resistors in the form of flat plates will be placed in such a way that the velocity vectors of the general movement of the product in natural or forced flow, in the vicinity of said surfaces, are parallel to the faces of the plates.

Dans des appareils de chauffage selon l'invention, présentant un écoulement naturel ou forcé du produit, de direction générale parallèle à une direction donnée, on peut utiliser des résistances en forme de plaque sensiblement plane placées parallèlement à la direction générale du mouvement du produit.In heating devices according to the invention, having a natural or forced flow of the product, of general direction parallel to a given direction, it is possible to use resistors in the form of a substantially flat plate placed parallel to the general direction of movement of the product.

Des résistances en forme de plaque plane rectangulaire allongée peuvent être pliées, par exemple en zigzag, selon leur longueur et placées de façon telle que leur largeur soit parallèle à la direction générale du mouvement du produit.Resistors in the form of an elongated rectangular flat plate can be folded, for example in a zigzag, according to their length and placed in such a way that their width is parallel to the general direction of movement of the product.

On peut aussi utiliser des résistances en forme de plaque de forme générale cylindrique, le cylindre étant engendré par une génératrice se déplaçant parallèlement à la direction générale du mouvement du produit en s'appuyant sur une directrice, ouverte ou fermée, de forme courbe, par exemple circulaire, ou de forme polygonale, plusieurs résistances cylindriques peuvent être placées de façon concentrique.It is also possible to use plate-shaped resistors of generally cylindrical shape, the cylinder being generated by a generator moving parallel to the general direction of movement of the product by resting on a director, open or closed, of curved shape, by circular example, or polygonal, several cylindrical resistors can be placed concentrically.

Les résistances peuvent être en forme de plaque de structure continue ou de structure discontinue.The resistors can be in the form of a plate of continuous structure or of discontinuous structure.

Par "structure continue" des resistances en forme de plaque on entend que la structure des résistances ne comporte pas de trou, ainsi des résistances de structure continue sont semblables à des tôles.By “continuous structure” of plate-shaped resistors is meant that the structure of the resistors does not have a hole, thus resistors of continuous structure are similar to sheets.

Par "structure discontinue" des résistances en forme de plaque on entend que la structure des résistances comporte des trous, ainsi des résistances de structure discontinue peuvent être constituées d'un tissu obtenu par tissage, tricotage, tressage ou torsadage. Elles peuvent aussi être constituées d'une tôle ajourée obtenue par découpage avec enlèvement de matière, par exemple par poinçonnage.By “discontinuous structure” of resistors in the form of a plate is meant that the structure of the resistors has holes, thus resistors of discontinuous structure can be made of a fabric obtained by weaving, knitting, braiding or twisting. They can also consist of a perforated sheet obtained by cutting with removal of material, for example by punching.

De préférence des résistances en forme de plaque de structure discontinue sont obtenues par découpage d'une pluralité de fentes dans une tôle et étirage dans une direction perpendiculaire aux fentes.Preferably plate-shaped resistors of discontinuous structure are obtained by cutting a plurality of slots in a sheet and stretching in a direction perpendicular to the slots.

Pour les résistances de structure discontinue formées d'un tissu ou obtenues par découpage et étirage on considère que le face des plaques est la surface qui enveloppe les reliefs des plaques.For the discontinuous structure resistors formed of a fabric or obtained by cutting and stretching, it is considered that the face of the plates is the surface which envelops the reliefs of the plates.

Les résistances sont réalisées en des matériaux, résistant à la corrosion. Ainsi, les résistances peuvent être en aciers inoxydables de nuancdes habituellement utilisées pour ce type de matériel, en aciers inoxydables réfractaires, on peut aussi utiliser des aciers spéciaux après qu'ils aient subi un traitement anticorrosion.The resistors are made of materials, resistant to corrosion. Thus, the resistors can be made of stainless steels of nuances usually used for this type of material, in refractory stainless steels, special steels can also be used after they have undergone an anticorrosion treatment.

Les surfaces des résistances peuvent être d'aspect sensiblement lisse, de préférence elles sont d'aspect rugeux. Cet aspect rugeux peut être obtenu par exemple par sablage.The surfaces of the resistors can be of substantially smooth appearance, preferably they are of rough appearance. This rough appearance can be obtained for example by sanding.

Des résistances dont les surfaces sont d'aspect rugeux sont plus particulièrement destinées à la réalisation d'appareils de chauffage objets de l'invention qui comportent des moyens d'entrée d'un liquide à chauffer et des moyens de sortie de la vapeur dudit liquide. En effect la rugosité des résistances favorise l'ébullition nucléée du liquide.Resistors whose surfaces are rough in appearance are more particularly intended for the production of heating devices objects of the invention which comprise means for entering a liquid to be heated and means for leaving the vapor of said liquid . In fact the roughness of the resistors promotes the nucleated boiling of the liquid.

Eventuellement, les surfaces des résistances peuvent être pourvues d'un revêtement, ce revêtement peut être poreux, afin de favoriser l'ébullition nuclée, il peut aussi être un revêtement anticorrosion de faible épaisseur par exemple en émail silicone ou en thermostable.Optionally, the surfaces of the resistors may be provided with a coating, this coating may be porous, in order to promote nucleated boiling, it may also be a thin anti-corrosion coating, for example made of silicone enamel or thermostable.

L'appareil de chauffage de produit diélectrique ou pratiquement diélectrique, selon l'invention, est utilisable notamment pour chauffer des produits chimiques peu ou pas conducteurs de l'électricité, mis en jeu dans des procédés industriels.The apparatus for heating a dielectric or practically dielectric product, according to the invention, can be used in particular for heating chemicals with little or no conductivity of electricity, used in industrial processes.

L'invention sera décrite ci-après en se référant plus particulièrement à un appareil de chauffage d'u'n produit liquide.The invention will be described below with particular reference to a device for heating a liquid product.

Cet appareil de chauffage est particulièrement destiné au chauffage des fluides caloporteurs utilisés dans les installations chimiques.This heater is particularly intended for heating heat transfer fluids used in chemical installations.

La compréhension de l'invention sera facilitée par les figures ci-jointes, qui illustrent à titre d'exemple, schématiquement et sans échelle déterminée, un mode de réalisation d'un appareil de chauffage selon la présente invention et un mode de réalisation de la structure d'une résistance.

  • La figure 1 est u'ne vue en coupe par un plan axial d'un mode de réalisation d'un appareil de chauffage selon l'invention.
  • La figure 2 est une vue partielle d'un mode de réalisation d'une résistance de structure discontinue.
  • La figure 3 est une vue partielle en coupe par le plan III-III de la résistance selon la figure 2.
The understanding of the invention will be facilitated by the attached figures, which illustrate by way of example, schematically and without a determined scale, an embodiment of a heating appliance according to the present invention and an embodiment of the resistance structure.
  • Figure 1 is a sectional view through an axial plane of an embodiment of a heating apparatus according to the invention.
  • Figure 2 is a partial view of an embodiment of a discontinuous structural resistance.
  • FIG. 3 is a partial view in section through the plane III-III of the resistor according to FIG. 2.

L'appareil de chauffage (1), objet de l'invention, représenté schématiquement figure 1, est plus particulièrement un appareil de chauffage de fluide caloporteur utilisé dans une installation industrielle.The heater (1), object of the invention, shown schematically in Figure 1, is more particularly a heater for heat transfer fluid used in an industrial installation.

Cet appareil de chauffage (1) comporte une enceinte (2) contenant le fluide caloporteur (3), dans le fluide caloporteur (3) sont immergées six résistances (4) et des moyens (5) pour relier les résistances (4) à un réseau de distribution électrique (6).This heating device (1) comprises an enclosure (2) containing the heat transfer fluid (3), in the heat transfer fluid (3) are immersed six resistors (4) and means (5) for connecting the resistors (4) to a electrical distribution network (6).

L'enceinte (2) est, selon le présent mode de réalisation, un récipient forme d'un corps (7) sensiblement cylindrique, fermé à ses extrémités par un couvercle (8) et un fond (9).The enclosure (2) is, according to the present embodiment, a container formed by a body (7) substantially cylindrical, closed at its ends by a cover (8) and a bottom (9).

L'enceinte (2) comporte à sa partie basse des moyens d'entrée (10) du fluide caloporteur à chauffer et au voisinage de sa partie haute des moyens de sortie (11) de fluide caloporteur chaud, ces moyens sont constitués par des conduites.The enclosure (2) comprises at its lower part inlet means (10) of the heat transfer fluid to be heated and in the vicinity of its upper part outlet means (11) of hot heat transfer fluid, these means consist of pipes .

La conduite d'entrée (10) est de préférence pourvue d'une vanne trois voies (12) permettant le vidange de l'appareil de chauffage (1The inlet pipe (10) is preferably provided with a three-way valve (12) allowing the emptying of the heating appliance (1

Les résistances (4), selon le mode de réalisation représenté figure 1, sont en forme de plaques planes sensiblement rectangulaires, leurs faces sont placées parallèlement à la direction de mouvement général du fluide dans l'appareil de chauffage, mouvement ascendant représenté par la flèche F. Elles sont maintenues en place à l'aide de supports isolants (14) fixés au corps (7) de l'enceinte (2).Resistors (4), according to the embodiment shown in Figure 1, are in the form of substantially rectangular flat plates, their faces are placed parallel to the general direction of movement of the fluid in the heater, upward movement represented by the arrow F. They are held in place using insulating supports (14) fixed to the body (7) of the enclosure (2).

Les six résistances (4) sont reliées l'une à l'autre en série par des barrettes conductrices (15), les deux résistances extrêmes comportent les moyens (5) pour relier l'ensemble au réseau de distribution électrique (6). Les connexions entre les résistances (4) et le réseau électrique (6) traversent le fond (9) de l'enceinte (2) par une ouverture (16) pourvue de moyens d'isolation électrique (17) et d'étanchéité.The six resistors (4) are connected to each other in series by conductive bars (15), the two extreme resistors include the means (5) for connecting the assembly to the electrical distribution network (6). The connections between the resistors (4) and the electrical network (6) pass through the bottom (9) of the enclosure (2) through an opening (16) provided with means of electrical insulation (17) and sealing.

Les résistances (4) et leur mode de liaison électrique n'ont été décrits ci-avant qu'à titre d'exemple et l'on ne sort pas du cadre de l'invention en remplaçant au moins une résistance (4) par plusieurs résistances élémentaires et/ou en établissant les liaisons électriques entre elles différemment.The resistors (4) and their mode of electrical connection have only been described above by way of example and it is not going beyond the ambit of the invention to replace at least one resistance (4) with several elementary resistances and / or by establishing the electrical connections between them differently.

Avantageusement l'enceinte (2) n'est pas totalement remplie de fluide caloporteur (3), dans l'espace libre (18) entre la surface du fluide caloporteur (3) et le couvercle (8) de l'enceinte on maintient une pression d'azote, le couvercle (8) étant pourvu d'une tubulure (19) à cet effet.Advantageously, the enclosure (2) is not completely filled with heat transfer fluid (3), in the free space (18) between the surface of the heat transfer fluid (3) and the cover (8) of the enclosure, a nitrogen pressure, the cover (8) being provided with a tube (19) for this purpose.

Les connexsons entre les résistances (4) et le réseau électrique (6) peuvent aussi être réalisées à travers une ouverture du couvercle (8), dans la zone du couvercle (8) non baignée par le fluide caloporteur.The connections between the resistors (4) and the electrical network (6) can also be carried out through an opening of the cover (8), in the area of the cover (8) not bathed by the heat transfer fluid.

Les conduits d'entrée (10) du fluide caloporteur à chauffer et de sortie (11) de fluide caloporteur chaud peuvent être reliées directement au circuit de mise en oeuvre du fluide chaud c'est-à-dire au circuit de chauffage de l'installation industrielle.The inlet pipes (10) of the heat transfer fluid to be heated and the outlet (11) of hot heat transfer fluid can be connected directly to the circuit for implementing the hot fluid, that is to say to the circuit for heating the industrial installation.

Les conduits d'entrée (10) du fluide caloporteur à chauffer et de sortie (11) du fluide caloporteur chaud peuvent être reliées à un échangeur de chaleur dans lequel est chauffé un autre fluide caloporteur, celui-ci étant mis en oeuvre dans le circuit de chauffage de l'installation industrielle. Une telle réalisation permet de mieux sauvegarder la propreté, et par voie de conséquence, les propriétes diélectriques du fluide caloporteur chauffé dans l'appareil de chauffage objet de la présente invention.The inlet pipes (10) of the heat transfer fluid to be heated and of the outlet (11) of the hot heat transfer fluid can be connected to a heat exchanger in which another heat transfer fluid is heated, this being used in the circuit for heating the industrial installation. Such an embodiment makes it possible to better safeguard the cleanliness, and consequently, the dielectric properties of the heat transfer fluid heated in the heating apparatus object of the present invention.

Les résistances (4) peuvent être réalisées en forme de plaques sensiblement planes de structure discontinue telle que représentée en vues partielles figures 2 et 3.The resistors (4) can be produced in the form of substantially flat plates of discontinuous structure as shown in partial views in FIGS. 2 and 3.

La résistance en forme de plaque de structure discontinue, dont un fragment est représenté figure 2, comporte des trous (19) sensiblement en forme de losange obtenus par découpage dans une tôle d'une pluralité de fentes alignées selon leur longueur et placées en quinconce, puis étirage dans une direction perpendiculaire aux fentes, c'est-à-dire parallèle aux petites diagonales des losanges. Cet étirage provoque une rotation des rubans (20) séparant les losanges (cf. figure 3). Selon ce mode de réalisation des résistances on considère que les faces des plaques sont les surfaces, matérialisées par les deux lignes discontinues (21, 22), qui enveloppent tous les reliefs des plaques.The plate-shaped resistor of discontinuous structure, a fragment of which is represented in FIG. 2, comprises holes (19) substantially in the form of a diamond obtained by cutting from a sheet of metal a plurality of slots aligned along their length and placed in staggered rows, then stretching in a direction perpendicular to the slits, that is to say parallel to the small diagonals of the diamonds. This stretching causes a rotation of the ribbons (20) separating the diamonds (cf. FIG. 3). According to this embodiment of the resistors, it is considered that the faces of the plates are the surfaces, materialized by the two broken lines (21, 22), which envelop all the reliefs of the plates.

Sur la figure 3 on a représenté les vecteurs vitesses V du mouvement général du fluide caloporteur en écoulement, les vecteurs vitesses V sont ici parallèles aux faces de la plaque, ce mouvement général ne tient pas compte des mouvements locaux, tels que les tourbillons T, crées par les reliefs de la plaque de structure discontinue. Ces tourbillons T, favorisent le transfert de chaleur entre la résistance et le fluide caloporteur.FIG. 3 shows the speed vectors V of the general movement of the flowing heat transfer fluid, the speed vectors V are here parallel to the faces of the plate, this general movement does not take account of local movements, such as the vortices T, created by the reliefs of the discontinuous structure plate. These T vortices favor the transfer of heat between the resistance and the heat transfer fluid.

Le procédé et l'appareil, objets de l'invention, présentent de nombreux avantages vis-à-vis des appareils selon l'art antérieur.The method and the apparatus, objects of the invention, have numerous advantages over the apparatuses according to the prior art.

En effet, la ou les résistances électriques étant immergées directement dans le produit diélectrique ou pratiquement diélectrique permettent un meilleur échange thermique car, avec le procédé de chauffage selon l'invention, la surface qui participe à l'échange thermique avec le produit à chauffer est la surface même par laquelle se dissipe l'effet Joule né dans la résistance. Ainsi, toute la surface de la résistance participe à l'échange avec le produit et l'écart de température entre la résistance et le produit est faible, ce qui limite les risques de dégradation thermique du produit qui est directement en contact avec la résistance.Indeed, the electrical resistance (s) being immersed directly in the dielectric or practically dielectric product allow better heat exchange because, with the heating method according to the invention, the surface which participates in the heat exchange with the product to be heated is the very surface through which the Joule effect born in resistance dissipates. Thus, the entire surface of the resistor participates in the exchange with the product and the temperature difference between the resistor and the product is small, which limits the risks of thermal degradation of the product which is directly in contact with the resistor.

La procédé et l'appareil de chauffage selon l'invention présentent aussi l'avantage de permettre la construction d'appareils de chauffage, notamment de chaudières, compacts. En effet, selon l'invention on peut disposer, pour des chaudières, d'une puissange électrique d'au moins 1 kW par litre d'encomprement de la zone d'échange de chaudière.The method and the heating device according to the invention also have the advantage of allowing the construction of compact heating devices, in particular boilers. In fact, according to the invention, it is possible to have, for boilers, an electrical power of at least 1 kW per liter of space in the boiler exchange zone.

La diminution du nombre et de l'encombrement des connexions électriques, par rapport aux dispositifs de chauffage comportant un faisceau de résistances électriques pourvues de gaines, favorise également la compacité des appareils de chauffage selon l'invention.The reduction in the number and size of the electrical connections, compared to heating devices comprising a bundle of electrical resistors provided with sheaths, also promotes the compactness of the heating devices according to the invention.

Un autre avantage des appareils de chauffage objets de l'invention, est que, de par la forme de plaque des résistances et de par leur positionnement de façon telle que les vecteurs vitesses du mouvement général du produit au voisinage des résistances soient tangents ou parallèles aux faces des plaques, les pertes de charges du produit dans l'appareil de chauffage sont relativement faibles. Ces pertes de charges relativement faibles pour un appareil destiné à chauffer un produit liquide permettent souvent un fonctionnement en thermosiphon de l'appareil ou à défaut une circulation assistée du liquide, sans nécessiter l'utilisation de moyens de pompages puissants. De plus, lorsqu'un tel appareil de chauffage est utilisé comme bouilleur, il permet une section libre de passage des bulles importante, contrairement aux bouilleurs selon l'art antérieur.Another advantage of the heating appliances which are the subject of the invention is that, by the shape of the resistors and by their positioning in such a way that the velocity vectors of the general movement of the product in the vicinity of the resistors are tangent or parallel to the faces of the plates, the pressure drops of the product in the heater are relatively low. These relatively low pressure drops for an appliance intended for heating a liquid product often allow thermosyphon operation of the appliance or, failing this, assisted circulation of the liquid, without requiring the use of powerful pumping means. In addition, when such a heater is used as a boiler, it allows a free passage section for large bubbles, unlike the boilers according to the prior art.

En outre, les appareils de chauffage selon l'invention sont de constructions et d'entretien aisés, les problèmes d'étanchéité au niveau des gaines des résistances étant très limités.In addition, the heaters according to the invention are easy to build and maintain, the sealing problems at the resistance sheaths being very limited.

Les avantages du procédé et de l'appareil de chauffage selon l'invention sont particulièrement intéressants à utiliser pour le chauffage de liquides diélectriques tels que les fluides caloporteurs.The advantages of the method and of the heating apparatus according to the invention are particularly advantageous to use for the heating of dielectric liquids such as heat transfer fluids.

Les exemples ci-après mettent en évidence les avantages du procédé et de l'appareil de chauffage mettant en oeuvre le procédé, objets de la présente invention, lors de diverses utilisations de l'appareil.The examples below demonstrate the advantages of the method and of the heating apparatus implementing the method, objects of the present invention, during various uses of the apparatus.

Exemple 1Example 1

Un a réalisé une chaudière sensiblement paral- lélepipédique. Elle est constituée d'un récipient surmonté d'un échangeur à air. Le récipient est en tôle partiellement calorifugé pour assurer, compte-tenu du système de régulation, un fonctionnement quasi permanent du chauffage. Elle comporte trois résistances, reliées en série, en forme de plaque rectangulaire allongée, pliée en zigzag selon leur longueur, et situées à des niveaux différents parallèlement au fond de la chaudière.One has produced a substantially parallelepipedal boiler. It consists of a container surmounted by an air exchanger. The container is made of partially insulated sheet metal to ensure, taking into account the regulation system, almost permanent heating operation. It has three resistors, connected in series, in the form of an elongated rectangular plate, zigzag folded along their length, and located at different levels parallel to the bottom of the boiler.

Les résistances sont des plaques de structure discontinue telles que représentées figure 2, elles dissipent une puissance de 2 kW.The resistors are plates of discontinuous structure as shown in Figure 2, they dissipate a power of 2 kW.

La chaudière est équipée de sondes de mesures de températures placées au-dessus et au-dessous des résistances.The boiler is equipped with temperature measurement probes placed above and below the resistors.

La chaudière, contient 30 litres de fluide caloporteur constitué de polyphényles partiellement hydrogénés, commercialisé sous le nom de GILOTHERM TH par la Société RHONE-POULENC SPECIALITES CHIMIQUES.The boiler contains 30 liters of heat transfer fluid consisting of partially hydrogenated polyphenyls, marketed under the name of GILOTHERM TH by the company RHONE-POULENC SPECIALITES CHIMIQUES.

Les essais ont été conduits par chauffage du GILOTHERM TH successivement:

  • 1 000 heures à 300°C
  • 500 heures à 340°C
  • 640 heures à 350°C.
The tests were carried out by heating the GILOTHERM TH successively:
  • 1000 hours at 300 ° C
  • 500 hours at 340 ° C
  • 640 hours at 350 ° C.

A 300°C la chaudière fonctionnait en thermosiphon, en convection naturelle.At 300 ° C the boiler operated in thermosyphon, in natural convection.

A 350°C on a noté la formation progressive de produits légers et la convection est devenue plus énergique: la chaudière fonctionnait en bouilleur thermosiphon. Le coefficient d'échange moyen était de 700 W/m2°C et l'écart de température entre la surface de la résistance et le GILOTHERM TH en ébullition de l'ordre de 24°C.At 350 ° C, the gradual formation of light products was noted and the convection became more energetic: the boiler operated as a thermosyphon boiler. The average exchange coefficient was 700 W / m2 ° C and the temperature difference between the surface of the resistor and the GILOTHERM TH in boiling range of around 24 ° C.

Entre chaque séquence d'essais, les résistances ont été sorties et observées: elles ne présentent aucune trace d'encrassement.Between each test sequence, the resistances were removed and observed: they show no trace of fouling.

Les analyses et les mesures des propriétés du fluide caloporteur mis en oeuvre dans la chaudière montrent que celui-ci n'a subi aucune dégradation.Analyzes and measurements of the properties of the heat transfer fluid used in the boiler show that it has not undergone any degradation.

Exemple IlExample II

Dans la même chaudière, en utilisant une résistance de 2 kW dissipant 40 kW/m2, on a chauffé pendant 288 heures à 255°C, un fluide caloporteur constitué de 26,5% en poids de diphényle et 73,5% en poids d'oxyde de phényle, commercialisé sous le nom de GILOTHERM DO par la Société RHONE-POULENC SPECIALITES CHIMIQUES. Le coefficient d'échange était de 2 000 kW/m2°C, l'écart de température entre la résistance et le fluide en ébullition était de 20°C.In the same boiler, using a resistance of 2 kW dissipating 40 kW / m 2 , was heated for 288 hours at 255 ° C, a heat transfer fluid consisting of 26.5% by weight of diphenyl and 73.5% by weight of phenyl oxide, marketed under the name of GILOTHERM DO by the company RHONE-POULENC SPECIALITES CHIMIQUES. The heat transfer coefficient was 2000 kW / m 2 ° C, the temperature difference between the resistance and the boiling fluid was 20 ° C.

Après cet essai la résistance a été démontée et examinée, aucune trace d'encrassement n'a été observée.After this test the resistance was dismantled and examined, no trace of fouling was observed.

Exemple IIIExample III

On a réalisé une chaudière parallélipipédique possédant une résistance susceptible de dissiper 250 W. On a introduit dans le récipient de la chaudière un mélange de terphényles constitué de 12% d'orthoterphényle, 60% de métaterphé- nyle, 28% de paraterphényle, ayant un point de fusion finale de 150°C, commercialisé sous le nom de terphényles OMP par la Société RHONE-POULENC SPECIALITES CHIMIQUES.A parallelepipedal boiler was produced having a resistance capable of dissipating 250 W. A mixture of terphenyls consisting of 12% orthoterphenyl, 60% metaterphenyl, 28% paraterphenyl, was introduced into the boiler container. final melting point of 150 ° C., marketed under the name of OMP terphenyls by the company RHONE-POULENC SPECIALITES CHEMIQUES.

Après solidification et refroidissement à la température ambiante on a réchauffé plusieurs fois le mélange de terphényles OMP jusqu'à 200°C.After solidification and cooling to room temperature, the mixture of OMP terphenyls was heated several times to 200 ° C.

La fusion du mélange de terphényles s'est effectuée sans difficulté, la résistance n'a pas été encrassée.The melting of the mixture of terphenyls was carried out without difficulty, the resistance was not fouled.

Exemple IVExample IV

Dans le même dispositif on a réchauffé aisément de la température ambiante à 240°C un mélange de polyisobutènes visqueux de masse molaire moyenne environ 900, commercialisé par la Société NAPHTACHIMIE sous le nom de NAP-VtS 10.In the same device, a mixture of viscous polyisobutenes with an average molar mass of around 900 was easily warmed from ambient temperature to 240 ° C., sold by the company NAPHTACHIMIE under the name of NAP-VtS 10.

Claims (13)

1. Process for heating a dielectric liquid consisting in immersing at least one bare resistor, to the terminals of which a potential difference is applied, directly in the said liquid contained in an enclosure, characterized in that for heating a liquid with a resistivity higher than 10° Ωlcm the liquid is conducted along plate-shaped resistors so that the velocity vectors of the general motion of the liquid under natural or forced flow, in the vicinity of the resistor or resistors are tangent or parallel to the faces of the said plates.
2. Process according to Claim 1, characterized in that a potential difference higher than 380 V is applied to the terminals of the resistor or resistors.
3. Apparatus for heating a dielectric liquid with a resistivity higher than 108 0/cm, with the aid of electrical energy, characterized in that it makes use of the heating process according to either of Claims 1 and 2.
4. Apparatus according to Claim 3, characterized in that it comprises an enclosure (2) containing the said liquid (3) in which at least one bare plate-shaped resistor (4) is immersed, the said plate-shaped resistor or resistors being placed so that the velocity vectors of the general motion of the liquid under natural or forced flow, in the vicinity of the resistor or resistors are tangent or parallel to the faces of the said plates, and means (5) for connecting the said resistor or resistors to an electrical supply system (6).
5. Apparatus according to Claim 4, characterized in that it comprises several resistors (4) connected electrically (15) in series and/or in parallel.
6. Apparatus according to Claim 4, characterized in that it comprises at least three resistors connected electrically in a triangle or star-fashion.
7. Apparatus according to any of Claims 4 to 6, chracterized in that the said enclosure is a length of conduit swept by the liquid to be heated.
8. Apparatus according to any one of Claims 4 to 6, characterized in that the said enclosure (2) consists of a receptacle (7, 8, 9) comprising means for the entry (10) of the liquid to be heated and means for the exit (11) of the hot liquid.
9. Apparatus according to any one of Claims 4 to 6, characterized in that the said enclosure consists of a receptacle comprising means for the entry of the liquid to be heated and means for the exit of the vapour of the said liquid.
10. Apparatus according to any one of Claims 4 to 9, characterized in that the resistor or resistors are in the shape of a substantially plane plate or of a substantially cylindrical plate.
11. Apparatus according to any one of Claims 4 to 10, characterized in that the resistor or resistors, plate-shaped, are continuous in structure.
12. Apparatus according to any one of Claims 4 to 10, characterized in that the resistor or resistors, plate-shaped, are noncontinuous in structure.
EP82420166A 1981-12-16 1982-11-26 Process and device for heating a dielectric or nearly dielectric liquid, and use of this device for heating, in particular of a calorific fluid Expired EP0082092B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82420166T ATE32643T1 (en) 1981-12-16 1982-11-26 METHOD AND DEVICE FOR HEATING A DIELECTRIC OR NEARLY DIELECTRIC LIQUID AND APPLICATION OF THIS DEVICE FOR HEATING SPECIFICALLY A HEAT TRANSFER.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8123790 1981-12-16
FR8123790A FR2518351B1 (en) 1981-12-16 1981-12-16 METHOD AND APPARATUS FOR HEATING DIELECTRIC OR SUBSTANTIALLY DIELECTRIC LIQUID AND USE OF SAID APPARATUS, IN PARTICULAR FOR HEAT FLUID

Publications (2)

Publication Number Publication Date
EP0082092A1 EP0082092A1 (en) 1983-06-22
EP0082092B1 true EP0082092B1 (en) 1988-02-24

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Application Number Title Priority Date Filing Date
EP82420166A Expired EP0082092B1 (en) 1981-12-16 1982-11-26 Process and device for heating a dielectric or nearly dielectric liquid, and use of this device for heating, in particular of a calorific fluid

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EP (1) EP0082092B1 (en)
AT (1) ATE32643T1 (en)
BR (1) BR8207165A (en)
CA (1) CA1195719A (en)
DE (1) DE3278148D1 (en)
FR (1) FR2518351B1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4938815A (en) * 1986-10-15 1990-07-03 Advantage Production Technology, Inc. Semiconductor substrate heater and reactor process and apparatus
US4778559A (en) * 1986-10-15 1988-10-18 Advantage Production Technology Semiconductor substrate heater and reactor process and apparatus
US5044314A (en) * 1986-10-15 1991-09-03 Advantage Production Technology, Inc. Semiconductor wafer processing apparatus
US4956046A (en) * 1986-10-15 1990-09-11 Advantage Production Technology, Inc. Semiconductor substrate treating method
US4891335A (en) * 1986-10-15 1990-01-02 Advantage Production Technology Inc. Semiconductor substrate heater and reactor process and apparatus
CA2680455C (en) 2007-03-12 2013-11-19 Dyno Nobel Inc. Detonator ignition protection circuit

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR351449A (en) * 1905-02-11 1905-07-17 Shoenberg Electric Appliance C Electric heater of a liquid
CH145649A (en) * 1930-02-24 1931-03-15 Georg Leffer Louis Method and device for uniform heating of fluids of all kinds by means of electrically heated resistors.
CH451351A (en) * 1967-05-30 1968-05-15 Balzers Patent Beteilig Ag Electric radiator
FR1600146A (en) * 1968-12-31 1970-07-20
DE2400478A1 (en) * 1974-01-05 1975-07-17 Eckerfeld Geb Reip Elisabeth Continuous water flow heater - has at least one bare heating coil in flow channel for direct heat transfer
DE2532377A1 (en) * 1975-07-19 1977-02-03 Licentia Gmbh Water heater with bottom heating element in tank - heats static water and additional top element is switched ON for flowing water
CH613329A5 (en) * 1977-01-05 1979-09-14 Petz Elektro Waerme Techn Resistance heating element for a heating device
US4292504A (en) * 1979-10-02 1981-09-29 Tutco, Inc. Expanded metal electric heating element with edge support

Also Published As

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BR8207165A (en) 1983-10-11
FR2518351B1 (en) 1985-06-21
FR2518351A1 (en) 1983-06-17
ATE32643T1 (en) 1988-03-15
DE3278148D1 (en) 1988-03-31
EP0082092A1 (en) 1983-06-22
CA1195719A (en) 1985-10-22

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