WO2017118821A1 - Applicateur micro-ondes monomode, dispositif et procede de traitement thermique de produits - Google Patents
Applicateur micro-ondes monomode, dispositif et procede de traitement thermique de produits Download PDFInfo
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- WO2017118821A1 WO2017118821A1 PCT/FR2017/050031 FR2017050031W WO2017118821A1 WO 2017118821 A1 WO2017118821 A1 WO 2017118821A1 FR 2017050031 W FR2017050031 W FR 2017050031W WO 2017118821 A1 WO2017118821 A1 WO 2017118821A1
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- Prior art keywords
- waveguide
- product
- exposure
- cavity
- injection
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Classifications
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- 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
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/78—Arrangements for continuous movement of material
- H05B6/782—Arrangements for continuous movement of material wherein the material moved is food
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- 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
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/70—Feed lines
- H05B6/701—Feed lines using microwave applicators
-
- 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
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/70—Feed lines
- H05B6/707—Feed lines using waveguides
-
- 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
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/78—Arrangements for continuous movement of material
- H05B6/784—Arrangements for continuous movement of material wherein the material is moved using a tubular transport line, e.g. screw transport systems
Definitions
- the present invention belongs to the field of the preparation, processing and preservation of all types of products to be subjected to a heat treatment. More particularly, the invention belongs to the field of heat treatment, by means of radio-electric microwaves, of products of all origins containing one or more polarized dielectric materials, that is to say materials generally considered as electrical insulators and whose molecule has an asymmetry of electrical charges, for example as the H20 water molecule.
- microwaves of the order of GHz or a few GHz for the preparation of food especially for their heating or cooking before consumption.
- a difficulty of the process implemented is to precisely control the illumination of seeds by microwaves to obtain the desired thermal effects, ensuring a homogeneous treatment of the seeds in an industrial flow, and without damaging the organoleptic qualities of the seeds.
- the present invention relates to a heat treatment applicator wherein the particulate product to be treated is exposed to electromagnetic microwave radiation in a cavity in which electromagnetic waves are injected.
- the cavity is, in the applicator of the invention, a section waveguide cavity adapted to a single-mode propagation, for a microwave frequency implemented, of an exposure waveguide, in which cavity the microwaves propagate in a longitudinal direction of the cavity.
- the cavity has a product inlet opening and a product outlet opening remote from the inlet opening in a longitudinal direction of the cavity, and the applicator includes a product conveying system in the guide of the product. waves in a continuous flow in the longitudinal direction of the cavity of the exposure waveguide between the inlet opening and the outlet opening.
- the transport system comprises separating partitions, formed of a material transparent to the radio waves implemented in the applicator, which determine adjacent sliding volumes moving in the cavity of the exposure waveguide, in the longitudinal direction of said exposure waveguide from the inlet opening to the outlet opening, so as to maintain a complete and uniform filling of the exposure waveguide by the product during the transportation of said product.
- At least one injection waveguide one end end of which is connected to the exposure waveguide, at a radio window of the exposure waveguide, injects microwave, propagating in said at least one injection waveguide, in the cavity of the exposure waveguide. It is thus introduced at a given point of the exposure waveguide a desired microwave energy.
- the applicator includes a plurality of injection waveguides and each waveguide is connected at one end end to the exposure waveguide at a radio window of the guide of the waveguide. exposure waves. Radio windows assigned to each of the exposure waveguides are distributed between the inlet opening and the outlet opening, offset from each other on the exposure waveguide in the longitudinal direction of said guideway. exposure waves.
- a power of the microwave radiation injected in the form of a microwave radiation into the cavity of the exposure waveguide by each of the injection waveguides is defined to determine a temperature curve based on the time of the product flowing in the exposure waveguide.
- the exposure waveguide is a waveguide in which the center line of the waveguide sections is circular, thereby forming a toric cavity
- the transport system includes a rotor, wherein the separating walls are driven, a rotation of which relative to a fixed structure of the exposure waveguide, constituting a stator, ensures and or control the transport of the product in the cavity.
- Such a shape is advantageous in terms of the mechanical simplicity of the drive system and its compactness.
- the exposure waveguide is an open waveguide at its ends, for example a cylindrical or substantially cylindrical cavity linear waveguide, or a helical cavity waveguide , and the transport system drives scrolling volumes sliding in the cavity of the exposure waveguide between the open ends, from an end corresponding to the inlet opening to the other end corresponding to the outlet opening.
- the drive system consists for example of a moving carpet to which the partition walls are attached.
- Such shapes benefit from a simple exposure waveguide to be achieved because the transport system is not associated with a movable wall and poses a priori little problem of microwave tightness of which it is appropriate to limit the leaks as much as possible.
- the exposure waveguide is a section waveguide adapted for single-mode propagation, of standardized dimensions for a frequency of 91 MHz, or a guide for single-mode, standardized-sized waves for a frequency of 2.45 GHz.
- the applicator comprises at least two injection waveguides, and a total CW microwave energy introduced into the cavity of the exposure waveguide is distributed between the injection waveguides.
- the total microwave energy CW is approximately half distributed in a first injection waveguide , substantially for a quarter in a second injection waveguide and substantially for a quarter in a third injection waveguide.
- the applicator includes a plurality of exposure waveguides of similar structures arranged to operate in parallel.
- the invention also relates to a device for heat treatment of a product containing at least one polarized dielectric material in which the product is exposed to electromagnetic microwave radiation from a wave generator in a cavity in which electromagnetic waves are injected, which comprises at least one applicator according to the applicator described above and comprises at least one continuous wave generator CW arranged to produce microwaves with an energy determined according to the product and temperatures at which the product must be worn and at a frequency corresponding to monomode propagation of microwaves in injection waveguides and in the exposure waveguide (s).
- the wave generator comprises at least one high frequency head of which a microwave energy produced is divided, by at least one divider, to be conveyed by at least two injection waveguides. to an exhibition waveguide.
- each injection waveguide includes an impedance adapter for modifying the impedance of the particular injection waveguide, the set of injection waveguides, impedance and dividers forming a wave distributor in which a distribution of the microwave power in each of the injection waveguides is networked by adjusting the impedance adapters. It is thus possible to modify the power distribution between injection waveguides without being limited to the inherent possibilities of the dividers.
- the microwave energy produced by a high frequency head is divided twice to be fed by three injection waveguides to the exposure waveguide.
- each divider is adjustable so as to adjust the power distribution in each of the divider outputs.
- a wave generator associated with an exposure waveguide delivers in operation a maximum total power, in the form of microwaves centered on a frequency of 915 MHz, of substantially 75 kW, power compatible with the maximum power currently attained by microwave generators in this frequency range.
- each injection waveguide comprises an impedance adapter to adapt its output impedance to the impedance of its charge in the exposure waveguide.
- the device allows the implementation of a method of treating a plant product by exposure to microwave radiation in an applicator according to the applicator of the invention, wherein the product is continuously transported in a cavity of the invention.
- exposure waveguide along a length of said cavity from the inlet opening of the cavity to the outlet opening of the cavity, wherein exposure waveguide the microwave radiation propagates according to single-mode propagation conditions.
- the microwave radiation is for example introduced into the exposure waveguide in at least two different injection locations following the length of the cavity. It is thus obtained conditions that can evolve during the transport of the product in the exposure waveguide so as to subject the product successively to the thermal conditions resulting from exposure to the electromagnetic fields determined for the product under consideration and the desired treatment.
- a distribution in each of the microwave power injection waveguides, produced by a high frequency head and divided to feed the injection waveguides, is networked. by adjusting impedance adapters of the injection waveguides.
- the product transport velocity in the exposure waveguide and continuous CW radiation power introduced into the exposure waveguide at each injection location are determined for heat the product according to a desired temperature curve as a function of time.
- the product is a mixture of products from two or three vegetable, animal and mineral sources.
- Treatment according to the method comprises, as the case may be, at least:
- Figure 1 a device according to the invention for the heat treatment of food products with the main subsets of the device;
- Figure 2 a first embodiment of a toric cavity single-mode exposure waveguide applicator
- FIG. 3 an example of a CW wave generator implementing a single high frequency head whose emitted power is distributed over three injection waveguides;
- FIG. 4 a device according to the invention embodying a second embodiment of a linear waveguide applicator
- FIG. 5 an example of a device comprising an applicator in which several toric cavity exposure waveguides are associated.
- FIG. 5 represents, as an exemplary embodiment, a drawing of a device according to the invention in a form and in proportions close to a device made with technology components available today and adapted to a industrial implementation.
- Figure 1 shows schematically a device 100 according to the invention for a product treatment by temperature.
- the products may be of plant origin or of animal origin or of mineral origin, provided that they contain one or more polarized dielectric materials absorbing the radio waves, in particular the radio waves in the microwave domain, that is to say, whose frequencies are between 800 MHz and 3 GHz according to current conventions.
- the term "product" 90 will be used in the description of the invention to denote the products to be treated by exposure to microwave radiation by means of the device.
- the same term and its reference will be used to designate the product in its various stages of the treatment to which it is subjected during its passage through the device 100, regardless of the physico-chemical transformations that it may undergo.
- the device 100 comprises an electromagnetic wave generator producing continuous waves, called CW (Continuous Waves), of the microwave domain, that is to say waves with frequencies between 800 MHz and 3GHz.
- CW Continuous Waves
- the frequency values used are not imposed and can be chosen according to technical constraints in each case.
- the generator is adapted to produce microwaves centered on a determined frequency whose choice is directly related to that of the transverse dimensions of the waveguides adapted to the propagation of said waves, waveguides which in the device of the invention are also implemented for the transport of products 90 to be treated.
- the electromagnetic wave generator of the device produces waves centered on a determined frequency, for example the frequency of 915 MHz which corresponds to a frequency allocated, administratively, to the public applications.
- a determined frequency for example the frequency of 915 MHz which corresponds to a frequency allocated, administratively, to the public applications.
- microwave frequency should be understood in the context of the invention as the frequency on which is centered an emission spectrum of the wave generator.
- the generator is a continuous wave generator capable of continuously delivering, at least over a period of time adapted to the time scale of its implementation in the device, a nominal power of said generator wave.
- the generator uses a modulation of the wave transmission duration to adjust an average power in a cycle of operation of the generator.
- Such a modulated mode of the duration of emission of microwaves is realized with a small period compared to a transport speed of the products exposed to microwaves in the context of the invention, considered as a generator operation. in CW continuous mode to obtain a continuous average power lower than the maximum continuous power.
- the device 100 comprises at least one continuous heating applicator 10 in which the products are transported between an inlet 1 1 of the applicator and an outlet 12 of the applicator.
- the products are transported in an exposure waveguide 30 of the applicator, following a longitudinal direction of a cavity 32 of said exposure waveguide.
- the longitudinal direction corresponds to a wave propagation direction in the waveguide.
- the products When transported in the exposure waveguide 30, the products are exposed to the microwaves produced by the wave generator 20 propagating longitudinally in said exposure waveguide in a single-mode propagation mode.
- the single-mode propagation of radio waves in a waveguide is known, and widely implemented in applications requiring the transfer of radio power with the minimum of loss, for example in radar devices for the transmission of radio waves.
- energy between a generator and an antenna is obtained by a section, perpendicular to the longitudinal direction, of the cavity of the waveguide in which propagates the radio wave adapted to the frequency of said radio wave.
- FIG. 2 illustrates an example of a focus 15 of the applicator 10 and having an exposure waveguide 30.
- the exposure waveguide 30 determines a toric cavity, of section chosen to ensure the monomode propagation of the waves used.
- the toric shape of the cavity is not limited to the only case of a circular section of the waveguide in an axial plane of the torus, a circular section generally considered in a purely mathematical definition of the torus.
- the torus determines a tubular cavity of substantially constant section, rectangular in the illustrated examples, and a line of the centers of the sections, describes a circle.
- the exposure waveguide 30 is also arranged to allow transport in the cavity of said exposure waveguide, at a controlled rate, the products to be exposed to microwaves.
- the exposure waveguide has a cavity of rectangular section substantially 248 mm wide and 124 mm high, dimensions that ensure monomode propagation of microwaves centered on said frequency.
- the exposure waveguide 30 has the main shape of a tube 31 whose walls are electrically conductive, for example made of a good electrically conductive material such as copper, aluminum, silver. .. or at least having a layer of an electrically conductive material deposited on inner walls of said tube, and a central portion of which determines a volume transparent to radio waves.
- the central portion of the waveguide tube is a cavity 32 containing, outside the product to be exposed to microwaves, air that is suitable for most considered exposure cases.
- the diagram of FIG. 2 corresponds to an O-shaped exposure waveguide with a cavity 32 of rectangular section in an axial plane of the torus.
- the exposure waveguide 30 has, in one wall of said exposure waveguide, an inlet opening 33, through which products 90 to microwave radiation is introduced into the cavity 32 of said waveguide, and an outlet opening 34, through which the products 90 having been exposed to microwave radiation emerge from said waveguide.
- a length L 0 of the exposure waveguide 30 between the inlet 33 and outlet 34 openings in which the products are transported determines a distance over which said products can be exposed to the microwaves.
- the exposure waveguide 30, in the example of FIG. 2, is fixed, at least in part, placed with an axis of revolution 35 of the horizontal torus, with the inlet opening 33 located at a point the top of the torus and the outlet opening 34 located at a low point of the torus, in the illustrated example substantially at a point diametrically opposite to the inlet opening.
- the exposure waveguide 30, at least one fixed wall of the tube 31 of said waveguide, constitutes, in mechanical terms, a stator of a transport system 40 of the products 90.
- the sliding volumes ensure a continuous transport of the products 90 subjected to microwave radiation in the toric cavity 32 with a controlled rate of progression of said products which are confined in a sliding volume by the walls of the tube 31 and the two separating partitions determining said sliding volume.
- the separating partitions 42 also make it possible to ensure a homogeneous product filling of the exposure waveguide. Indeed, on the one hand the product is maintained in the sliding volume where it has been placed, without being able to move randomly in the cavity of the waveguide until its exit through the outlet opening 34, and on the other hand a complete filling of the sliding volume with the product avoids the formation of a heterogeneity within said sliding volume, as would be the case in case of a partial filling, when the product is transported.
- the separating partitions 42 are separated by a separation distance between adjacent partitions, following the perimeter of said toric cavity, to determine a product loading capacity of a sliding volume 43.
- the choice of a separation distance between the separating partitions 42 is determined so that a volume comprised between two adjacent partitions is always full of the product 90 when said volume is in a portion of the exposure waveguide 30 into which the microwaves are injected. It is understood that the volume is considered full of the product when the loading device implemented no longer allows to introduce more product into the volume in question, even in the presence of interstitial voids between the grains of the material.
- This filling condition, in practice as homogeneous as possible, of the sliding volumes 43 in the cavity of the exposure waveguide where the products are exposed to the microwaves, is important to obtain a homogeneous density of the product in the guide. exposure wave, which results in an electromagnetic field also homogeneous within the treated products.
- the partitions are angularly separated by 30 ° so as to form six successive sliding volumes rotating in the cavity of the exposure waveguide, in the illustrated case where the exposure to microwaves is carried out on a angular sector of 180 °.
- this value of 30 ° is not limiting and will be as much as of need adapted, in value higher or lower value, to the treated product and its behavioral characteristics so as to ensure a complete filling of the volumes and the necessary flow product to fill and empty volumes.
- the separating partitions 42 are made of a material that is transparent to the electromagnetic waves of the frequencies considered, for at least one low attenuation material, so that the microwaves propagate in the cavity 32 of the exposure waveguide with a minimum mitigation related to compartmentalization of slippery volumes 43.
- parts of the rotor in particular walls of the waveguide directly or indirectly supporting the partitions, are formed in conductive materials and arranged relative to the other parts of the waveguide to prevent leakage. microwaves and radiant energy losses.
- a microwave frequency of 915 MHz corresponds to a standardized waveguide with a cavity section 247.65 mm x 123.82 mm.
- the microwave radiation is in single-mode propagation.
- an adapted standardized waveguide (WR340 or R26) has a cavity section of 86.36 mm x 43.18 mm.
- the device 100 also comprises a microwave dispenser for supplying the energy to the applicator 10.
- FIG. 2 shows three injection waveguides 29a, 29b, 29c which convey the microwaves from the wave generator 20 to the exposure waveguide 30.
- Each of the injection waveguides is substantially tangentially coupled to the exposure waveguide 30 by a radio window 28a, 28b, 28c, respectively. so as to ensure, in the illustrated example, a propagation of the microwaves in the toric cavity 32 in a direction of transport of the products 90 in said toric cavity of the exposure waveguide, ie in the direction rotation of the rotor 41 a.
- injection waveguides 29a, 29b, 29c are coupled to the exposure waveguide 30 each at different locations between the inlet aperture 33 and the exit aperture 34 so as to determine in the cavity 32 of said exposure waveguide of the successive exposure areas along the length L 0, each exposure zone corresponding to a volume of the exposure waveguide 30 subjected mainly to the energy of the injected waves by one of the injection waveguides and absorbed by the product.
- each of the exposure zones corresponds to an angular sector of a portion of the toric cavity 32 in which the products 90 are transported between the point high and low point of said exposure waveguide.
- the electromagnetic wave generator 20 produces microwaves in each of the injection waveguides 29a, 29b, 29c with a desired power to be injected into the exposure area corresponding to the guide. injection wave considered.
- the electromagnetic wave generator 20 may comprise a plurality of high frequency heads producing microwaves, a head being assigned to a only injection waveguide or a limited number of injection waveguides.
- each high frequency head is arranged to enable the power sent to be adjusted in the corresponding injection waveguide.
- the electromagnetic waves being of the same frequencies for the set of injection waveguides 29a, 29b, 29c, said generator of FIG.
- the electromagnetic wave comprises a single high frequency head 21 whose energy is divided and adjusted according to the powers to be provided in each injection waveguide.
- a first divider 23a divides the total power of the high frequency head 21 by half on each of two outputs of said first divider.
- a first output of the first divider 23a is connected to a first injection waveguide 29a to have 50% of the microwave energy produced by the high frequency head 21.
- the power remaining on a second output of the first divider 23a is again divided by half between two outputs of a second divider 23b which are each connected to a second and third injection waveguide, 23a, 23b, to have each 25% of the microwave energy produced by the high frequency head 21.
- each waveguide 23a, 23b, 23c comprises an impedance adapter, 24a, 24b, 24c respectively, for adjusting the output impedances to the load impedances corresponding to the product exposed in the exposure waveguide. the adaptation being carried out as a function of information transmitted by probes 25 for measuring the energy emitted and the energy reflected in each waveguide.
- a recirculator 26 is arranged at the exit of the high frequency head 21 to trap waves that would otherwise be reinjected into the generator.
- each impedance adapter 24a, 24b, 24c of an injection waveguide is implemented to control the power delivered in said injection waveguide so that the dispenser
- the resulting wave forms an energy network management system which adjusts the power distribution provided by the high frequency head 21 between the different injection waveguides.
- an impedance adapter 24a, 24b, 24c restores on the network the power initially distributed to it by the dividers 23a, 23b but which is not used, that is to say, which has not been absorbed by the product. This restored power can then be used by the other injection waveguides.
- the energy can be accurately distributed to match the thermal profile in the exposure waveguide, without being dependent only on the proper dividing factors of the dividers 23a, 23b.
- the distribution of the power between the different injection waveguides, as well as the effective power of the electromagnetic radiation in each injection waveguide, will be adapted by those skilled in the art depending on the type of products treated by the device, whose absorption capacities and thermal behavior are different from one product to another, the flow of products treated in the exposure waveguide, for example a mass flux in g / s , and also the temperatures at which the products must be carried in each of the exposure zones according to the desired effects on the products.
- the powers in each injection waveguide are adjusted during implementation of the applicator based on measured parameters such as product temperature at different locations of the exposure waveguide. .
- a granular product 90 naturally or following a preparation, to be treated by heating is in a first step placed in a supply distributor 50, for example a tank having a hopper for driving the product into a conduit substantially to the section of the exposure waveguide to an inlet 11 of the applicator 10.
- a supply distributor 50 for example a tank having a hopper for driving the product into a conduit substantially to the section of the exposure waveguide to an inlet 11 of the applicator 10.
- the product is driven for example by gravity, by a hopper, by screw or by any other known system suitable for the transport of the product in question, in particular its particle size, its fluidity and its texture, in particular to avoid a jam or clogging in transport from the reservoir to the exposure waveguide 30.
- the duct is advantageously substantially of the section of the exposure waveguide implemented in the device to ensure a stable progression of the product to the inlet opening 33 of the exposure waveguide.
- the product once introduced into the exposure waveguide 30 through the inlet aperture 33, is continuously transported at a controlled rate into said exposure waveguide by the rotor 41a through at the exit aperture 34.
- the product 90 is subjected to preheating before being introduced into the cavity of the exposure waveguide.
- Preheating for example at a chosen value of between 30 ° C. and 55 ° C. and having no appreciable effect on the products to be treated, makes it possible to reduce the microwave power required to raise the temperature of the product in the guide. wave exposure and allows to introduce the product in the exposure waveguide with a temperature and therefore initial conditions in the substantially constant waveguide.
- the transport speed of the product 90 is imposed by the rotational speed of the rotor 41a from which a given duration of exposure of the product to the microwave radiation conditions results. in each of the areas of the exposure waveguide receiving microwave energy from the injection waveguides 29a, 29b, 29c.
- this exposure time is particularly stable and reproducible because the product is substantially immobile inside the sliding volumes 43.
- the rotor 41a is advantageously rotated at a constant speed by a motor, for example an electric or hydraulic motor.
- the rotor may be free to rotate and be rotated by gravity under the effect of the weight of the product, subject to a path followed by the descending product in the waveguide, the rotor speed being within this case advantageously regulated by a brake.
- the transported product 90 is contained in the sliding volumes 43, between the separating partitions 42, a configuration which results in a continuous flow and a perfect control of the passage times in the exposure waveguide, and in each of the zones of the exposure waveguide corresponding to the different microwave energy input of each of the injection waveguides, of all the volumes of product transported between the separating partitions 42.
- the transport of the product by the rotor 41a limits the risk of clogging of the exposure waveguide with respect to uncompressed flow of the product, for example gravity flow, when the product does not exhibit a sufficiently fluid behavior for a gravity flow in the exposure waveguide.
- the wave generator 20 is kept in operation to generate the continuous microwaves (CW) which are injected into the cavity 32 of said waveguide by the injection waveguides 29a, 29b, 29c.
- CW continuous microwaves
- the impedances are adapted for each waveguide so as to compensate for variations in the dielectric characteristics of the treated product.
- the microwave energy injected into the exposure waveguide 30 has been absorbed by the product, the energy injected levels being adjusted. as much as necessary depending on the product treated and the implementation parameters to obtain this result, a residual energy being optionally retained by a conventional microwave trap.
- the tangential or at least oblique injection of the microwaves by the injection waveguides 29a, 29b, 29c into the exposure waveguide 30 limits the risks of reflections which would have the negative consequence of reinjecting a part of the waves towards the source or sources 22 of the microwave generator 20.
- the maximum microwave energy produced continuously, at the frequency used of 915 MHz, by the generator is 75 kW.
- This power is, if necessary, adjustable to lower values to meet specific conditions and microwave absorption capabilities by the product to be heated.
- the microwave radiation energy level sensors in the cavity 32 of the exposure waveguide transmit energy level measurements, measurements used to determine at any time the absorption capabilities. of the product and by a regulation system to adjust in real time the microwave powers injected by the various injection waveguides 29a, 29b, 29c.
- the first injection waveguide 29a first following the path of the product in the exposure waveguide 30, receives about 50% of the energy produced by the generator. wave 20, or at most continuously, in the example considered, a power of 37.5 kW which is injected into a first exposure zone.
- this first exposure zone it is in these conditions carried out a rise in temperature of the product without extraction of water.
- the temperature of the seeds is brought to 85 ° C. during this first exposure, homogeneous temperature in the product under consideration with variations maximums obtained by the process below five degrees centigrade.
- the second injection waveguide 29b receives about 25% of the energy produced by the generator, ie in the example at most continuously a power of 18.75 kW which is injected into a second exposure zone and which brings the temperature of the product to 1 15 ° C.
- Exposure to these temperatures also allows to denature the lypases contained in the seeds and which are responsible for the degradation of the seeds and their by-products, as for example the oils which will be extracted from the seeds in a later stage of use of the seeds. product treated by the process.
- a benefit of the control of the temperature and its homogeneity in the product during this phase makes it possible to obtain the desired result throughout the volume of the treated product while preserving the structure of the food components and without modifying the organoleptic qualities of the product.
- the third injection waveguide 29c receives about 25% of the energy produced by the generator, in the example at most continuously, a power of 18.75 kW which is injected into a third exposure zone in which the temperature reached in the second zone is maintained.
- this third zone it is realized in the example of oleaginous seeds, an extraction of water which is adjusted to maintain a desired quantity of residual water, for example of the order of 4%, so as to preserve the aptitudes the pressing of the product and subsequently to the treatment of better pressing conditions and a more complete extraction of oil contained in the product.
- the power effectively transferred to the product by each injection waveguide can be controlled by means of the impedance adapters.
- this distribution of the energy in the cavity 32 of the exposure waveguide 30 results in a homogeneous heating of the product and a temperature curve as a function of the time to which the product is subjected during its transport. in said exposure waveguide.
- This temperature curve can be adjusted by modifying the parameters such as the powers injected into the exposure waveguide by each injection waveguide, or by implementing a number of injection waveguides. different from three as in the example described, for example one, two or four injection waveguides, or more, or such that the speed of travel of the material in the exposure waveguide.
- the temperature obtained, resulting from the interactions of the microwaves with the material of the product, is in the device particularly homogeneous.
- the granular product 90 arrives opposite the opening of 34, it is removed from the applicator to an outlet 12 for subsequent processing, packaging, storage or use of the treated product.
- the treated product is removed from the gravity exposure waveguide.
- evacuation modes may however be implemented, alone or in combination, for example a blowing of the product, for example a mechanical forcing.
- a blowing of the product for example a mechanical forcing.
- the number of injection waveguides may be different from three, as well as the power in each of the injection waveguides different from the described embodiment.
- the number of injection waveguides and the power provided by each of said injection waveguides are adapted to distribute energy flows injected into the exposure waveguide, flux of energy from which results for a product, a temperature profile as a function of the position in the exposure waveguide, that is to say as a function of time, to which it is desired to subject the product during its circulation in the exposure waveguide.
- the temperature at which the product is carried results from the direct absorption of the microwave energy by said product and that said temperature is a function not only of the microwave power introduced in the guide of the product. exposure wave, but also the ability of the product to absorb said microwave energy.
- the angular sector traversed by the product is not necessarily limited as in the example illustrated at an angle of 180 °.
- this angle may be less than or greater than 180 °, without being limited by gravity constraints.
- the axis of the toric cavity exposure waveguide, or the axis of rotation of the rotor is not necessarily horizontal and can have any orientation in space, for example vertical.
- the rectangular cavity, rectangular cavity waveguide in the first embodiment described may have other shapes.
- FIG. 4 illustrates a device according to the principles of the invention in which the exposure waveguide is linear.
- a side wall of the exposure waveguide is not shown to view the product in said waveguide.
- the cavity of the waveguide is also of rectangular section and of dimensions adapted to the propagation of microwaves in single-mode mode.
- the product 90 traverses the cavity 32 of the exposure waveguide from an inlet opening 33 through which said product is introduced, to an outlet opening 34 through which the treated product leaves.
- the drive system 40 advantageously consists of a continuous belt 41b forming a loop functionally identical to the rotor 41a which is adapted to transport the product, deposited on said belt, along an axis of the waveguide exposure.
- the exposure waveguide 30 is oriented with a longitudinal axis of said horizontal exposure waveguide, and in this case the product can be deposited so as to fill volumes.
- sliders 43 determined by separating partitions 42, vertical in the example shown, to ensure a filling of said sliding volumes and a volume density of the product in the substantially constant exposure waveguide.
- the separating partitions guarantee, on the one hand, that the waveguide is kept homogeneously filled and, on the other hand, the progression of the product without risk of slippage of the product with respect to the carpet. Uncontrolled slippage of the product on the carpet, or mixing of the product, would alter the exposure time of the product to the microwaves or randomize the exposure time of a product item, alter the product density in the product. exposure waveguide in an unpredictable manner, disrupting the propagation of microwaves, and could lead to clogging of the waveguide, phenomena which must be avoided in order to respect the temperature profiles of the product in the guide of exposure waves.
- the use of separating partitions makes it possible to place the longitudinal axis of the exposure waveguide in any position, for example inclined, or even vertical, without producing a flow of product in the direction longitudinal waveguide that would not maintain a constant density density in the exposure waveguide.
- a line of the centers of the sections of the exposure waveguide may have any trajectory, for example a spiral, for example with a curved part and a rectilinear part, making it possible, if necessary, to increase the number of radio windows by which the microwaves are injected into the exposure waveguide without necessarily increasing the diameter of a toroidal waveguide or without necessarily reducing a distance between two radio windows, provided that that a transport system can be implemented to provide the speed-controlled transport of the product over the exposure length of said exposure waveguide while maintaining waveguide filling.
- the microwaves are introduced into the exposure waveguide by radio windows 28a, 28b, 28c with an angle of incidence of the injection waveguides 29a, 29b, 29c, preferably less than 30.
- an angle of incidence of the injection waveguides 29a, 29b, 29c preferably less than 30.
- the radio windows are closed by plates of a microwaves-transparent dielectric material which prevent the product or dust from getting into one of the waveguides. injection waves.
- the rectangular section considered of the guide exposure waves in the embodiments described is adapted to the means used to carry out the controlled transport of the product in the cavity of said exposure waveguide, this form of the section is not imposed and that shapes of different sections, for example circular, oval or polygonal, can be used as long as the chosen section leads to a monomode propagation of the waves in the cavity of the exposure waveguide and is adapted to the complete filling of the sliding volumes 43.
- a device in improved embodiments for increasing product processing capabilities, includes a plurality of exposure waveguides arranged in parallel.
- FIG. 5 illustrates an exemplary device comprising three exposure waveguides, in accordance with the first exemplary embodiment described, with toric cavities and carrying the product transport by means of rotors.
- the exposure waveguides share, for example, a rotation drive of the rotors, assembled on the same axis of rotation, by a common motor, for example a product distributor, for example a treated product collector. or a wave generator.
- a common motor for example a product distributor, for example a treated product collector. or a wave generator.
- the arrangement of several exposure waveguides in parallel operation makes it possible in practice to increase a treated product flow because for each exposure waveguide the flow rate is constrained by the section of the cavity of said guide.
- exposure wave imposed by the single-mode propagation of the waves, and by the exposure times of the treated product which limits the speed of movement of said product in the exposure waveguide.
- the invention thus makes it possible to continuously process a large quantity of product in an industrial installation.
- a treatment may consist of a simple heating to bring a product to a given temperature, for example for a subsequent processing operation, heating which will be with the invention obtained quickly with a uniform temperature in the product.
- a treatment may consist of a dehydration, more or less thorough, a product containing water, the ability to follow a precise profile of temperature variations to control the level of dehydration and side effects sought or that it is wished to avoid.
- a treatment may consist of cooking a product, stewed or not.
- the exposure waveguide at least in the part in which this braising is performed, is made with a sufficient seal to maintain a level of heated vapor or overheated to cook.
- a treatment may consist of roasting.
- a treatment may consist of thermal sterilization.
- a treatment may consist of steam cracking, that is to say the cutting of long molecules contained in the product in the presence of water vapor.
- a treatment can consist of a skinning, that is to say the separation of an envelope or a film of a grain, here carried out by a vaporization of water contained in the product, the vapor causing a mechanical separation envelope or film.
- Treatment may consist of extensive dehydration of minerals by evaporation of bound water retained in the dry material.
- the device and method of the invention are directed to any treatment of a product, containing at least one polarized dielectric material that can be heated by exposure to radio-electric microwaves, requiring place the product under precise temperature conditions following a thermal cycle.
- treatments may apply to products of plant origin, products of animal origin or products of mineral origins, which may be raw products, processed products or elaborate products.
- a requirement for the implementation of the device is that the product must have a granular shape, that is to say be sufficiently fractionated and have a physical structure to ensure the filling, complete and homogeneous, and the emptying of the slippery volumes that carry the product in the exposure waveguide.
- the grains will preferably be of rounded shapes or with soft edges to facilitate the flow of the product and limit the risk of blockages that produce grains with sharp edges.
- the grains or unitary elements of the product also have dimensions and shapes that ensure a relatively complete and homogeneous filling of the exposure waveguide by the product opposite interactions between the material and the microwaves used, and despite the inevitable voids between the grains.
- the person skilled in the art will ensure that the filling of the sliding volumes and the waveguide, resulting from the characteristics of the grains, lead to a substantially isotropic medium, in all the waveguide of exposure, with respect to the electromagnetic waves used.
- An advantage of the invention in the processing of products is the rapid heating of the product and the homogeneity of the temperatures obtained in the volume of the product, heating requiring substantially less energy than heaters by conventional methods using thermal conduction of the product when exposed to a source of heat.
- Another advantage lies in the possibility of creating, by an adaptation of the applicator, the number of injection waveguides and the locations on the exposure waveguide and the microwave powers injected into the guide. of exposure waves by each of the injection waveguides, a profile of temperatures as a function of the time the product is subjected to.
- Another advantage is the continuous operation of the applicator which is traversed by a product flow which allows to process large quantities of product in a reduced time compared to conventional solutions.
- the macroscopic grains of the granular product to be treated in the device correspond, for example, to products naturally occurring in a granular form, such as raw vegetable seeds, for example wheat grains, hazelnuts or walnut kernels, and weights. ..
- Such macroscopic grains are for example processed products such as fractionated or crushed and calibrated materials, and which meet the constraints of dimensions and shapes explained above.
- split products may, for example, result from the cutting of plant leaves, fruits, vegetables, tubers or any other divisible product.
- Such macroscopic grains are, for example, elaborated products such as, for example, food croquettes intended for human consumption or animal feed, or wood pellets intended for combustion.
- the product may also be in the form of a powder, for example a flour of plant or animal origin, for example a mineral powder.
- the product may also be in the form of a liquid, more or less viscous, for example an oil, for example an aqueous or non-aqueous solution, for example an emulsified polyphasic liquid.
- a liquid more or less viscous
- an oil for example an aqueous or non-aqueous solution, for example an emulsified polyphasic liquid.
- the device can be implemented for the heat treatment of plant products such as seeds, fruits, tubers, leaves or any other part of plants.
- cereal seeds such as: maize, wheat, barley, rye, oats, rice, sorghum and in general the seeds of grasses ...
- fruits consumed as vegetables such as: cucurbitaceae fruits, Solanaceae fruits ... or consumed as fleshy fruits such as: berries, drupes, apples ... or other fruits such as: citrus, pineapple. ..
- the treated seeds are, for example, so-called oleaginous seeds, or so-called proteinaceous seeds, or so-called oleoproteaginous seeds.
- the treatment of plant products is for example intended to modify the water content of the product, either to bring this content to a desired value for conservation reasons or to bring this water content to a value suitable for further processing of the product.
- the treatment of plant products is for example intended for a physicochemical transformation, such as, for example, the denaturation of enzymes responsible for the degradation of the product during its storage.
- the product is subjected to a CW continuous microwave radiation for a period of the order of 180 seconds in which a temperature profile as a function of time is chosen to denature the phospholypase enzymes degrading the organoleptic qualities of treated products.
- the treatment of the products can be a cooking, braising or no, a roasting, a roasting.
- Braising is carried out in the exposure waveguide advantageously by reusing the superheated steam produced during heating, and the drying is advantageously carried out by evaporation of the water with suction of the steam through a porous wall of the stator.
- the treatment of the products can be carried out on the products for example for food or feed purposes, for cosmetic purposes, for medicinal purposes or for purely physicochemical purposes, for example for the preparation of dyes.
- the products may also be shaped products, such as the plant products mentioned above, which have undergone transformations to occur for example in the form of flakes, small pieces, powders ...
- the products can also be elaborate products such as granules manufactured for human or animal food purposes, wood pellets intended for combustion ...
- the products can also be of animal origin, for example flours.
- the products can also be of mineral origin, for example ores or powders.
- the device, the applicator and the method of the invention make it possible to raise the temperature of the products to a desired value, the temperature being obtained rapidly with a reduced energy cost, and the precise temperature being obtained homogeneously throughout the entire volume of the product. product.
- Prototype-stage tests have made it possible to measure accuracies and temperature differences between the different locations in the volume of the heated material below five degrees centigrade, which in most cases results in a homogeneous treatment of the products.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Constitution Of High-Frequency Heating (AREA)
- Food Preservation Except Freezing, Refrigeration, And Drying (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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BR112018013905A BR112018013905A2 (pt) | 2016-01-06 | 2017-01-05 | aplicador de micro-ondas de modo único, dispositivo e método para tratamento térmico de produtos |
EP17701175.6A EP3400757A1 (fr) | 2016-01-06 | 2017-01-05 | Applicateur micro-ondes monomode, dispositif et procede de traitement thermique de produits |
US16/068,326 US11523476B2 (en) | 2016-01-06 | 2017-01-05 | Single-mode microwave applicator, device and method for thermal treatment of products |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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FR1650084A FR3046518B1 (fr) | 2016-01-06 | 2016-01-06 | Applicateur micro-ondes monomode, dispositif et procede de traitement thermique de produits |
FR1650084 | 2016-01-06 |
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WO2017118821A1 true WO2017118821A1 (fr) | 2017-07-13 |
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PCT/FR2017/050031 WO2017118821A1 (fr) | 2016-01-06 | 2017-01-05 | Applicateur micro-ondes monomode, dispositif et procede de traitement thermique de produits |
Country Status (6)
Country | Link |
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US (1) | US11523476B2 (fr) |
EP (1) | EP3400757A1 (fr) |
AR (1) | AR107308A1 (fr) |
BR (1) | BR112018013905A2 (fr) |
FR (1) | FR3046518B1 (fr) |
WO (1) | WO2017118821A1 (fr) |
Families Citing this family (2)
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GB201908940D0 (en) | 2019-06-21 | 2019-08-07 | C Tech Innovation Ltd | Electromagnetic heating reactor |
CN116159849A (zh) * | 2023-01-09 | 2023-05-26 | 中车山东机车车辆有限公司济南低碳科技分公司 | 一种连续热解装置与方法 |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0036362A1 (fr) * | 1980-03-13 | 1981-09-23 | Joel Soulier | Dispositif pour le traitement thermique de matières en poudres ou en grains |
WO2007007068A1 (fr) * | 2005-07-11 | 2007-01-18 | Re18 Limited | Récipient, appareil de chauffage et procédé de chauffage d'une charge de départ |
DE102005049533B3 (de) * | 2005-10-17 | 2007-01-25 | Püschner Gmbh & Co. Kg | Mikrowellen-Durchlaufofen |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3535795A (en) * | 1968-09-06 | 1970-10-27 | Varian Associates | Process of drying lithocarpus densiflora rehd. (tanoak) wood with radio wave energy |
JPS58191998A (ja) * | 1982-05-06 | 1983-11-09 | 動力炉・核燃料開発事業団 | 環状槽型マイクロ波加熱装置 |
NZ206150A (en) * | 1983-11-04 | 1987-06-30 | Nz Government | Food processor; screw conveyor pitch wider in microwave chamber than preheating chamber |
US6294773B1 (en) * | 1999-07-14 | 2001-09-25 | Chung Jing-Yau | Microwaving in a carousel with magnetrons below a food product isolated by a nonconductor |
US20080179318A1 (en) * | 2007-01-30 | 2008-07-31 | Christopher John Cornwell | Apparatus and Method for Vacuum Microwave Drying of Food Products |
HUE047217T2 (hu) * | 2007-10-15 | 2020-04-28 | Enwave Corp | Készülék és eljárás szerves anyagok mikrohullámú vákuumszárítására |
PL2525675T3 (pl) * | 2010-01-18 | 2015-08-31 | Enwave Corp | Suszenie mikrofalowo-próżniowe materiałów organicznych |
US20130172526A1 (en) * | 2011-12-29 | 2013-07-04 | Eastman Chemical Company | Wood treatment method and apparatus employing laterally shiftable transportation segments |
-
2016
- 2016-01-06 FR FR1650084A patent/FR3046518B1/fr active Active
-
2017
- 2017-01-05 EP EP17701175.6A patent/EP3400757A1/fr active Pending
- 2017-01-05 US US16/068,326 patent/US11523476B2/en active Active
- 2017-01-05 BR BR112018013905A patent/BR112018013905A2/pt not_active Application Discontinuation
- 2017-01-05 AR ARP170100032A patent/AR107308A1/es unknown
- 2017-01-05 WO PCT/FR2017/050031 patent/WO2017118821A1/fr active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0036362A1 (fr) * | 1980-03-13 | 1981-09-23 | Joel Soulier | Dispositif pour le traitement thermique de matières en poudres ou en grains |
WO2007007068A1 (fr) * | 2005-07-11 | 2007-01-18 | Re18 Limited | Récipient, appareil de chauffage et procédé de chauffage d'une charge de départ |
DE102005049533B3 (de) * | 2005-10-17 | 2007-01-25 | Püschner Gmbh & Co. Kg | Mikrowellen-Durchlaufofen |
Also Published As
Publication number | Publication date |
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AR107308A1 (es) | 2018-04-18 |
FR3046518A1 (fr) | 2017-07-07 |
US20190029084A1 (en) | 2019-01-24 |
BR112018013905A2 (pt) | 2018-12-18 |
FR3046518B1 (fr) | 2021-04-02 |
EP3400757A1 (fr) | 2018-11-14 |
US11523476B2 (en) | 2022-12-06 |
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