Classifications

• • 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
  • H05B6/80—Apparatus for specific applications
  • H05B6/802—Apparatus for specific applications for heating fluids
• • 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

Definitions

• TITLE Microwave reactor for continuous microwave treatment of a flowing fluid medium
• the present invention relates to a microwave reactor for continuous microwave treatment of a flowing fluid medium, as well as to an associated microwave installation and to a continuous microwave treatment process. of a flowing fluid medium.
• the invention is in the field of continuous microwave treatment of a flowing fluid medium, such as a liquid medium, a viscous medium, a pasty medium, a medium in a liquid / solid or liquid / gas two-phase mixture.
• a flowing fluid medium such as a liquid medium, a viscous medium, a pasty medium, a medium in a liquid / solid or liquid / gas two-phase mixture.
• the invention finds a preferred, but not limiting, application in the continuous microwave heat treatment of pumpable products, in particular agrifood products and in particular homogeneous liquid products or products with pieces regularly distributed in a sufficiently carrier phase.
• an RM microwave reactor generally called a “downstream” reactor, comprising a flow tube TE made of material transparent to microwaves, a GO waveguide connected to a microwave generator and coupled to the TE flow tube for continuous microwave treatment of the fluid medium, and an EN enclosure inside which extends at least in part the TE flow tube, such an enclosure EN being made of a material reflecting microwaves.
• a flow tube TE extending longitudinally along a flow axis and, on the other hand, a wave guide GO having a rectangular section with two long sides GC (ie sides with the largest dimension) and two short sides PC (ie. sides with the smallest dimension), where the long sides GC of the waveguide GO are orthogonal to the axis d flow, while the short sides PC of the waveguide GO are parallel to the flow axis.
• Such a “downstream” reactor proves to be relatively effective for fluid media which are not very absorbent, that is to say having a low loss coefficient. dielectric (or a low loss angle, a low loss tangent, a low delta tangent or a low loss factor).
• dielectric or a low loss angle, a low loss tangent, a low delta tangent or a low loss factor.
• the microwaves pass through the fluid medium fairly easily because the dielectric losses are low and moreover the field absorbed in the fluid medium is fairly homogeneous.
• such a “downstream” reactor proves to be relatively ineffective for absorbent, or even very absorbent, fluidic media, that is to say having a high dielectric loss coefficient (or a high loss angle, a strong tangent loss, a strong delta tangent or a high loss factor), such as water-based media, certain solvents for extraction, food products such as compote, certain chemicals, etc.
• a high dielectric loss coefficient or a high loss angle, a strong tangent loss, a strong delta tangent or a high loss factor
• the electric field (Ey) in a waveguide of rectangular section is typically distributed parallel to the short sides (b) of the waveguide, and is maximum in the middle of the long sides ( a) the waveguide.
• the electric field will, on the one hand, have difficulty penetrating into the medium and, on the other hand, reflect the waves because the electric field will see a border and a very abrupt change in dielectric losses at the level of the flow tube because:
• the electric field is parallel to the short sides PC of the waveguide GO and is therefore parallel to the flow tube TE in which the fluid medium flows, and
• the electric field is maximum in the middle of the long sides GC of the GO waveguide, that is to say where the TE flow tube is placed.
• the object of the present invention is in particular to propose a microwave reactor for continuous microwave treatment of a flowing fluid medium, which is particularly suitable both for low-absorbency fluid media and also for fluid media. very absorbent.
• An object of the invention is to allow a homogeneous or uniform heating, without localized hot spot at the level of the fluid medium.
• a microwave reactor for continuous microwave treatment of a flowing fluid medium comprising:
• a flow tube made of material transparent to microwaves, extending longitudinally along a flow axis for a flow of the fluid medium along said flow axis;
• an input waveguide extending along a propagation axis for microwave propagation along said propagation axis, said input waveguide having a rectangular section with two long sides defining a large dimension and two small sides defining a small dimension smaller than the large dimension, and said input waveguide being coupled to the flow tube for continuous microwave treatment of the fluid medium, with the flow axis orthogonal to the axis of propagation;
• the microwave reactor according to the invention being remarkable in that:
• the long sides of the input waveguide are parallel to the flow axis, while the short sides of the input waveguide are orthogonal to the flow axis;
• the enclosure has a lateral dimension measured parallel to the short sides of the input waveguide, said lateral dimension being greater than the small dimension of the input waveguide, said input waveguide being fixed transversely on the enclosure, said enclosure having an entry window surrounded by the entry waveguide for propagation of microwaves through the entry window inside the enclosure;
• the enclosure extends longitudinally along the flow axis over a given enclosure length between a first end and a second opposite end, said enclosure length being strictly greater than the large dimension of the waveguide d 'Entrance.
• the electric field is parallel to the short sides of the input waveguide and is therefore orthogonal (or perpendicular) to the flow tube in which the fluid medium flows, and thus the electric field will not see any border or sudden transition towards high dielectric losses because it will be able to bypass the flow tube, even in the case of absorbent fluidic media or with high dielectric losses.
• this coupling between the inlet waveguide and the flow tube will promote the penetration of waves all around the tube, thus creating a more uniform heating over the section of the flow tube.
• the latter is surrounded by an enclosure forming a cavity extending on each side of the input waveguide, and thus the wave will remain progressive and be almost completely absorbed before reaching the ends of the drain tube.
• the enclosure length is between 1.5 and 6 times greater than the large dimension of the input waveguide.
• This characteristic ensures progressive absorption of microwaves by an absorbent fluid medium, and avoids the appearance of a resonance phenomenon inside the enclosure: when this enclosure has a length of enclosure less than or equal to the large dimension of the input waveguide, the absorption of the microwaves is not progressive along the flow axis, thus promoting the formation of hot spots inside the fluid medium, leading to heterogeneous heating thereof.
• the enclosure is of circular section with a diameter corresponding to the lateral dimension.
• the entry window is delimited by two longitudinal edges parallel to the long sides of the entry waveguide and by two lateral edges parallel to the short sides of the entry waveguide, where the longitudinal edges have a length less than or equal to the large dimension and the lateral edges have a length less than or equal to the small dimension.
• the entry window is of rectangular section equivalent or smaller than the rectangular section of the entry waveguide.
• the longitudinal edges of the entry window have a length less than the large dimension and the lateral edges of the entry window have a length equal to the small dimension, so that the entry window forms an iris d 'Entrance.
• the input waveguide is fixed to the enclosure by an input window having the characteristic of longitudinal edges smaller than the long sides of the input waveguide, thus forming an input iris.
• Such an input iris is an important parameter on which the user can play in modeling to adapt to the fluid medium in flow for the purpose of optimizing the treatment.
• the iris shape of the entry window causes a modification of the microwave module passing through such an entry iris, making it possible to improve the penetration of these microwaves into the fluid medium circulating in the tube d 'flow.
• the entry window does not form an entry iris.
• the enclosure has no internal element arranged between the entry window and the drain tube.
• the portion of the enclosure located between the inlet window and the flow tube is unoccupied and in particular does not have any element capable of modifying or hindering the propagation of microwaves from the entry window to the drain tube.
• the enclosure does not include any device for circulating a cooling fluid around said flow tube, making it possible to control the temperature of the fluid medium flowing in the latter.
• this helical tube is then positioned parallel to the short sides of the input waveguide (and therefore parallel to the electric field of microwaves circulating in it) and prevents the propagation of microwaves in the flow tube.
• the microwave reactor comprises an output waveguide fixed transversely to the enclosure in a diametrically opposite manner to the input waveguide, where:
• - Said output waveguide extends along the axis of propagation and has a rectangular section with two long sides defining a large dimension and two short sides defining a small dimension less than the large dimension, the long sides of the guide d the outlet waves being parallel to the flow axis, while the short sides of the outlet waveguide are orthogonal to the flow axis, the large dimension of the outlet waveguide being equivalent to the large dimension of the input waveguide and the small dimension of the output waveguide being equivalent to the small dimension of the input waveguide;
• - Said enclosure has an outlet window diametrically opposite to the inlet window and surrounded by the outlet waveguide for propagation of microwaves through the outlet window.
• the exit window is delimited by two longitudinal edges parallel to the long sides of the exit wave guide and by two lateral edges parallel to the short sides of the exit wave guide, where the longitudinal edges have a shorter length. or equal to the large dimension and the lateral edges have a length less than or equal to the small dimension.
• the exit window is of rectangular section equivalent to or smaller than the rectangular section of the exit waveguide.
• the longitudinal edges of the exit window have a length less than the large dimension and the lateral edges of the exit window have a length equal to the small dimension, so that the exit window forms an iris of exit.
• the output waveguide is fixed to the enclosure by an output window having the characteristic of longitudinal edges smaller than the long sides of the output waveguide, thus forming an output iris.
• the exit window does not form an exit iris. It can thus be provided to have only one entry iris (as described above), or to have only one exit iris, or to have one entry iris and one exit iris .
• the microwave reactor further comprises a short-circuit device fixed to the output waveguide, said short-circuit device being either of the short-circuit piston type adjustable along the axis of propagation, either of the static short-circuit type.
• the enclosure is closed opposite the input waveguide and thus offers a curved reflecting surface situated diametrically opposite the input waveguide.
• the input waveguide is fixed transversely to the enclosure:
• the flow axis is a vertical axis so that the flow tube and the enclosure extend vertically
• the propagation axis is a horizontal axis so that the waveguide input extends horizontally.
• the enclosure rests in height on a support base, such as a support base provided with several support feet, so that the enclosure is raised from the ground by the support base.
• a support base such as a support base provided with several support feet
• the enclosure has covers provided on the first end and the second end, said covers being provided with connection sleeves for connecting a first end and a second end of the flow tube respectively to a first pipe. and to a second pipe of a flow system for a flow of the fluid medium.
• the enclosure can have a constant diameter over its entire length, or alternatively the enclosure can have a diameter which reduces at its ends so that the enclosure can be conical or truncated at the ends.
• the microwave reactor includes another input waveguide extending parallel to the propagation axis, said other input waveguide having a rectangular section with two long sides defining a large dimension and two short sides defining a small dimension less than the large dimension, and said other input waveguide being coupled to the tube d flow for continuous microwave treatment of the fluid medium;
• the lateral dimension of the enclosure is greater than the small dimension of said other input waveguide, said other input waveguide being fixed transversely on the enclosure, said enclosure having another window input surrounded by said other input waveguide for propagation of microwaves through said other input window inside the enclosure, and
• enclosure length is strictly greater than the large dimension of said other input waveguide.
• the microwave reactor comprises, in addition to the input waveguide, another other input guide arranged parallel to it and having similar structural and geometric characteristics.
• This other input waveguide thus makes it possible to introduce microwaves into the enclosure by means of another input window offset relative to the input window along the axis of flow.
• microwave offset relative to the axis of propagation of the input waveguide allows a better treatment of the fluid medium flowing in the flow tube (in particular, a more homogeneous treatment along the 'flow axis), especially when this fluid medium is highly absorbent.
• the other input waveguide is identical to the input waveguide, and in particular has a large dimension and a small dimension identical to those of said input waveguide.
• the other input waveguide is made of the same material as the input waveguide, so that the kinematics of the propagation of the microwaves in this other waveguide input is identical to that in the input waveguide.
• the input waveguide and the other input waveguide are connected to the same upstream waveguide provided for the introduction of microwaves inside each of said guides input waveguide and other input waveguide, said upstream waveguide having a rectangular section with two large sides defining a large dimension and two small sides defining a small dimension less than the large dimension, the large sides of said upstream waveguide being parallel to the flow axis, while the short sides of said upstream waveguide are orthogonal to the flow axis.
• the function of the upstream waveguide is therefore to transmit the microwaves propagating within it to each of the input waveguide and the other input waveguide.
• the large dimension of the upstream waveguide is equivalent to the large dimension of the input waveguide and of the other input waveguide, and that the small dimension of the upstream waves is equivalent to the small dimension of the input waveguide and the other input waveguide.
• the propagation of microwaves in the upstream waveguide is identical to that in the input waveguide and in the other input waveguide.
• the microwave reactor comprises another output waveguide fixed transversely to the enclosure in a diametrically opposite manner to the other input waveguide, where:
• - Said other output waveguide extends parallel to the axis of propagation and has a rectangular section with two large sides defining a large dimension and two small sides defining a small dimension less than the large dimension, the large sides of the other outlet waveguide being parallel to the flow axis, while the short sides of the other outlet waveguide are orthogonal to the flow axis, the large dimension of the other output waveguide being equivalent to the large dimension of the other input waveguide and the small dimension of the other output waveguide being equivalent to the small dimension of the other waveguide 'input waves;
• - Said enclosure has another outlet window diametrically opposite to the other inlet window and surrounded by the other outlet waveguide for propagation of microwaves through the other outlet window.
• the microwave reactor includes another output waveguide associated with the other input waveguide, this other output waveguide having similar structural and geometric characteristics and the same function as the output waveguide associated with the input waveguide.
• this other output waveguide may have the same large dimension and the same small dimension as the output waveguide and the input waveguide.
• This other output waveguide can also, in the same way as the output waveguide, be provided with a short-circuit device, for example of the short-circuit piston type adjustable parallel to the axis. propagation or static short circuit type.
• the present invention also relates to a microwave installation for continuous microwave treatment of a flowing fluid medium, such a microwave installation comprising:
• - a delivery system connected to the upstream and downstream flow tube to ensure a flow of the fluid medium inside the flow tube.
• the microwave reactor has another input waveguide, it is advantageous that the microwave generator of the microwave installation is also connected to this other input waveguide.
• the microwave reactor is as described above and includes an upstream waveguide connected to the input waveguide and to the other input waveguide, it is advantageous the microwave generator of the microwave installation is connected to this upstream waveguide: it is then indirectly connected both to the input waveguide and to the other waveguide entry.
• the microwave generator generates microwaves, for example in at least one of the microwave frequency bands for industrial, scientific and medical (ISM) use allocated by the International Telecommunication Union (ITU), and in particular the microwave frequency bands 2,450 GHz ⁇ 50.0 MHz, 5,800 GHz ⁇ 75.0 MHz, 433.92 MHz ⁇ 0.87 MHz, 896 MHz ⁇ 10 MHz and 915 MHz ⁇ 13 MHz.
• ISM industrial, scientific and medical
• the invention also relates to a process for continuous microwave treatment of a flowing fluid medium, such a process for continuous microwave treatment comprising the following steps:
• FIG.1 is a schematic view of a "downstream" microwave reactor of the state of the art
• FIG.2 is a schematic representation of an electric field inside a waveguide of rectangular section
• FIG.3 is a schematic view of a microwave reactor according to a first embodiment of the invention.
• FIG.4 is a schematic sectional view of the reactor of Figure 3, according to a sectional plane comprising the flow axis and orthogonal to the short sides of the input waveguide, with an illustration of the amplitude of the electric field in an example of absorbing fluid medium or with high dielectric losses, on a logarithmic scale
• FIG.5 is a schematic sectional view of the reactor of Figure 3, according to a sectional plane comprising the flow axis and orthogonal to the short sides of the input waveguide, with an illustration of the amplitude of the electric field in an example of an absorbing fluid medium or with high dielectric losses, on a linear scale;
• FIG.6 is a schematic sectional view of the reactor of Figure 3, according to a section plane orthogonal to the flow axis and passing through the middle of the input waveguide, with an illustration of the amplitude of the electric field in the example of an absorbing fluid medium or with high dielectric losses of FIGS. 4 and 5, on a logarithmic scale;
• Fig.7 is a schematic perspective view of a microwave reactor according to the invention, with an output waveguide on which is fixed an adjustable short-circuit piston short-circuit device along the axis of propagation;
• FIG.8 is a schematic perspective view of a microwave reactor according to the invention, with an output waveguide on which is fixed a short-circuit device of the static short-circuit type;
• FIG.9 is a schematic perspective view, from another angle, of the microwave reactor according to Figures 7 and 8, without the short-circuit device
• FIG.10 is a schematic sectional view of the microwave reactor according to Figures 7 and 8, without the short-circuit device, along a section plane comprising the flow axis and orthogonal to the short sides of the input waveguide;
• FIG. 1 is a schematic perspective view of a microwave installation according to the invention, equipped at least with the microwave reactor according to Figures 7 and 8 and a microwave generator connected to the guide input waves.
• FIG.12 is another schematic perspective view of a microwave installation according to the invention, equipped at least with the microwave reactor according to FIGS. 7 and 8 and a microwave generator connected to the input waveguide.
• FIG. 13 is a schematic perspective view of a second embodiment of the microwave reactor according to the invention, comprising another input waveguide.
• a microwave reactor 1 constitutes a reactor for continuous microwave treatment of a flowing fluid medium, that is to say that is to say a fluid medium which flows or which is in displacement.
• This microwave reactor 1 finds a preferred, but nonlimiting, application in the continuous microwave thermal treatment of pumpable products, in particular agrifood products and in particular homogeneous liquid products or products with pieces regularly distributed in a sufficiently carrier.
• This microwave reactor 1 comprises a flow tube 2 of cylindrical shape, made entirely of dielectric material and transparent to microwaves, such as borosilicate glass, quartz, alumina, polymeric material such as polytetrafluoroethylene or PTFE.
• This flow tube 2 extends longitudinally along a flow axis 20 and has a first end 21 and a second end 22 opposite, for a flow of the fluid medium inside the flow tube 2 along this flow axis 20 from the first end 21 to the second end 22.
• This flow axis 20 constitutes the central axis or axis of revolution of the cylindrical flow tube 2.
• the flow axis 20 is a vertical axis.
• This microwave reactor 1 comprises an enclosure 3 inside which extends the flow tube 2, where this enclosure 2 is made of a material reflecting microwaves, such as a conductive material or a metallic material.
• This enclosure 3 is cylindrical in shape with a given diameter DE, and it extends longitudinally along the flow axis 20 over a given length of enclosure LE between a first end 31 and a second end 32 opposite; this flow axis 20 constituting the central axis or axis of revolution of this cylindrical enclosure 3.
• the flow tube 2 and the enclosure 3 extend vertically, or alternatively they extend horizontally or at an angle with respect to a vertical or horizontal axis.
• the diameter DE of the enclosure 3 can be adjusted as a function of the diameter of the flow tube 2 as well as the properties of the fluid medium.
• the internal diameter and the external diameter of the flow tube 2 can also be adjusted according to the properties of the fluid medium.
• this enclosure 3 can rest in height on a support base 7 provided with several support feet 70, possibly support feet 70 adjustable vertically.
• the enclosure 3 surrounds the flow tube 2 and it has:
• a first connection sleeve 34 fixed on the first cover 33 and connected in leaktight manner to the first end 21 of the flow tube 2 so as to be able to connect a first pipe 61 in leaktight manner (visible in Figures 7, 1 1 and 12) at the first end 21 of the flow tube 2;
• connection sleeve 36 fixed on the second cover 35 and tightly connected to the second end 22 of the flow tube 2 so as to be able to connect a second pipe 62 (visible in FIGS. 7, 11 and 12) ) at the second end 22 of the flow tube 2.
• the fluid medium arrives in the flow tube 2 via the first pipe 61, circulates from the first end 21 to the second end 22 then leaves via the second pipe 62, so that the first pipe 61 forms the pipe upstream and the second pipe 62 forms the downstream pipe.
• the direction of flow of the fluid medium can be reversed in the flow tube 2 as explained below.
• the first end 21 connected to the first pipe 61 is provided at the bottom, while the second end 22 connected to the second pipe 62 is provided at top, so that the fluid medium flows in the flow tube 2 from bottom to top, which has the advantage of reducing or even avoiding the formation of bubbles or inhomogeneities in the fluid medium.
• an inverted direction of flow that is to say from the bottom to the top.
• the flow axis 20 and the flow tube 2 can be horizontal, so that the fluid medium flows horizontally. It is also conceivable that the flow axis 20 and the flow tube 2 are inclined relative to a horizontal axis or a vertical axis by an angle less than 90 degrees.
• This microwave reactor 1 further comprises an input waveguide 4 fixed transversely to the enclosure 3, in other words on its peripheral wall or around its periphery.
• This input waveguide 4 is made of a material reflecting microwaves, such as a conductive material or a metallic material.
• this input waveguide 4 is fixed by welding to the enclosure 3.
• This input waveguide 4 has a rectangular section with two large sides 41 defining a large dimension GD (ie. Sides having the largest dimension) and two small sides 42 defining a small dimension PD less than the large dimension GD ( ie. sides with the smallest dimension); the large dimension GD corresponding to the length of the rectangular section and the small dimension PD corresponding to the width of the rectangular section.
• This input waveguide 4 has a free termination 43 provided with a crown or connection plate suitable for allowing bolting junction with an upstream waveguide 8 (see FIGS. 1 1 and 12), for connection of the input waveguide 4 with a microwave generator 9.
• this free termination 43 forming a crown or connection plate is provided with holes around its entire periphery for the passage of screws.
• This input waveguide 4 extends along a propagation axis 40 for propagation of microwaves, coming from the microwave generator 9, along said propagation axis 40; it being noted that this propagation axis 40 is orthogonal to the flow axis 20. In the examples of FIGS. 7 to 12, the propagation axis 40 is therefore a horizontal axis, and thus the input waveguide 4 extends horizontally.
• the upstream waveguide 8 can be vertical and / or be horizontal and / or have elbows and / or be formed of several waveguide sections depending on the arrangement and location of the micro generator. -waves 9 with respect to the microwave reactor 1 and according to the inclinations of the flow axis 20 and the propagation axis 40.
• This input waveguide 4 is coupled to the flow tube 2 for continuous microwave treatment of the fluid medium circulating in the flow tube 2.
• the enclosure 3 has an input window 37 of rectangular shape, surrounded by the input waveguide 4 for propagation of the microwaves, coming from the microwave generator 9 and which propagate in the inlet waveguide 4, through the inlet window 37 inside the enclosure 3 where the flow tube 2 is located.
• the short sides 42 of the input waveguide 4 are orthogonal to the flow axis 20;
• the diameter DE of the enclosure 3 is greater than the small dimension PD of the input waveguide 4.
• the input waveguide 4 is fixed transversely to the enclosure 3 substantially in the middle (or halfway length or half-height) of the enclosure 3, ie generally at a distance from the first end 31 (or from the second end 32) of between 0.4 and 0.6 times the length of the enclosure LE.
• entry window 37 of rectangular shape or section, is delimited by:
• the longitudinal edges 371 of the entrance window 37 are rectilinear while the lateral edges 372 of the entrance window 37 are arched.
• the input window 37 is surrounded by the input waveguide 4, and therefore its longitudinal edges 371 have a length less than or equal to the large dimension GD and its lateral edges 372 have a length less than or equal to the small PD dimension.
• the longitudinal edges 371 of the entry window 37 have a length less than the large dimension GD and the lateral edges 372 of the entry window 37 have a length equal to the small dimension PD, so that the entry window 37 forms an entry iris.
• the entry window 37 is in the background while the exit window 38 is in the foreground.
• the longitudinal edges 371 of the entry window 37 have a length equal to the large dimension GD and the side edges 372 of the entry window 37 have a length equal to the small dimension PD, and thus the entry window 37 does not form an entry iris.
• the length of the enclosure LE is clearly greater (here, approximately 6 times greater) than the large dimension GD of the input waveguide 4.
• This characteristic makes it possible to ensure a homogeneous treatment, along the flow axis 20, of the fluid medium flowing in the flow tube 2 by the microwaves coming from the input waveguide 4, without cause the appearance of a resonance phenomenon in enclosure 3.
• the microwave reactor 1 has no element disposed between the inlet window 37 and the flow tube 2 and likely to disturb or hinder the propagation of microwaves from this inlet window 37 to this flow tube 2.
• the microwave reactor 1 can also comprise an outlet waveguide 5 fixed transversely to the enclosure 3 in a diametrically opposite manner to the inlet waveguide 4.
• This outlet waveguide 5 is produced in a microwave reflective material, such as a conductive material or a metallic material.
• this output waveguide 5 is fixed by welding to the enclosure 3.
• This output waveguide 5 also extends along the propagation axis 40, in alignment with the input waveguide 4.
• This output waveguide 5 has a rectangular section with:
• the enclosure 3 has an outlet window 38 diametrically opposite to the inlet window 37 of rectangular shape and surrounded by the outlet waveguide 5 for propagation of microwaves through the outlet window 38 between the output waveguide 5 and the interior of the enclosure 3.
• This output waveguide 5 has a free termination 50 provided with a crown or connection plate suitable for allowing a junction by bolting with a short-circuit device 55, 56 fixed on the output waveguide 5.
• this crown or connection plate is provided with holes around its entire periphery for the passage of screws.
• this short-circuit device is of the short-circuit piston type 55 adjustable along the axis of propagation 40; such a short circuit piston 55 having a conventional impedance matching function.
• the short-circuit piston 55 thus makes it possible to provide flexibility with the impedance matching so that the microwave reactor 1 can respond to large windows of the dielectric characteristics of the fluid medium.
• the enclosure 3 can be closed opposite the input waveguide 4 and thus offer a curved reflecting surface (instead of the outlet window 38) located diametrically opposite the input waveguide 4 and thus forming a static short circuit.
• outlet window 38 of rectangular shape or section, is delimited by:
• the longitudinal edges 381 of the outlet window 38 are straight while the side edges 382 of the outlet window 38 are arcuate.
• the outlet window 38 is surrounded by the outlet waveguide 5, and therefore its longitudinal edges 381 have a length less than or equal to the large dimension GD and its lateral edges have a length less than or equal to the small dimension PD.
• the longitudinal edges 381 of the outlet window 38 have a length less than the large dimension GD and the lateral edges 382 of the outlet window 38 have a length equal to the small dimension PD, so that the exit window 38 forms an exit iris.
• the longitudinal edges 381 of the outlet window 38 have a length equal to the large dimension GD and the lateral edges 382 of the outlet window 38 have a length equal to the small dimension PD, and thus the exit window 38 does not form an exit iris.
• FIG. 13 illustrates a second embodiment, in which a microwave reactor 1 ′ comprises, in addition to the input waveguide 4 previously described, another input waveguide 4 ’.
• the microwave reactor 1 ′ has the same elements as the microwave reactor 1 illustrated in particular by FIG. 7 and described above, and in particular: the enclosure 3 surrounding the flow tube 2 extending along the flow axis 20,
• the input waveguide 4 extending along the propagation axis 40 and having the large dimension GD and the small dimension PD, the large dimension GD being parallel to the flow axis 20, and
• the microwave reactor 1 ’ also includes another input waveguide 4’ fixed to the enclosure 3 and extending along another propagation axis 40 ’, parallel to the propagation axis 40.
• the input waveguide 4 is here fixed at a distance from the first end 31 approximately equal to 0.3 times the length of the enclosure LE, and that the other input waveguide 4 'is fixed at a distance from the first end 31 approximately equal to 0.7 times the length of the enclosure LE (or, equivalently, at a distance from the second end 32 approximately equal to 0.3 times the length of pregnant LE).
• This other input waveguide 4 ’ is also in all respects similar to the input waveguide 4; it is in particular made of a material reflecting microwaves, so as to allow propagation of microwaves along the other propagation axis 40 ′, and has a rectangular section with two long sides 41 ′ defining a large dimension GD equal to the large dimension GD of the input waveguide 4 and two small sides 42 'defining a small dimension PD equal to the small dimension PD of the input waveguide 4.
• This other input waveguide 4 ′ also surrounds another input window (not visible in FIG. 13) formed in the enclosure 3 and allowing, in the same way as the input window 37 previously described, to the microwaves circulating in the other input waveguide 4 ′ to enter the enclosure 3.
• this other entry window has the shape of an entry iris, when this other entry window has longitudinal edges of length equal to the large dimension GD and side edges of length equal to the small dimension PD.
• the microwave reactor 1 ' also comprises, in this second embodiment, another output waveguide 5' fixed on the enclosure 3 opposite the other input waveguide 4 'and extending along the other propagation axis 40'.
• This other output waveguide 5 ′ has a structure and a geometry identical to that of the output waveguide 5: it is in particular made of a material reflecting microwaves, so as to allow propagation of micro- waves along the other propagation axis 40 ', and has a rectangular section with two long sides 51' defining a large dimension GD equal to the large dimension GD of the other input waveguide 4 '(and of the guide of output waves 5) and two short sides 52 'defining a small dimension PD equal to the small dimension PD of the other input waveguide 4' (and of the output waveguide 5).
• This other outlet waveguide 5 ′ also surrounds another outlet window (not visible in FIG. 13) formed in the enclosure 3, diametrically opposite the other inlet window and allowing, in the same way as the outlet window 38 previously described, using microwaves circulating in the other outlet waveguide 5 'to exit the enclosure 3.
• this other exit window 38 has the shape of an exit iris, when this other exit window has longitudinal edges of length equal to the large dimension GD and lateral edges of length equal to the small dimension PD.
• this other output waveguide 5 ′ is fixed to another short-circuit device of the short-circuit piston type 55 ′ adjustable along the other propagation axis 40 ′, identical to the short-circuit device. short circuit piston type circuit 55 and having the same function.
• the other input waveguide 4 ′ therefore allows microwave propagation in an identical manner to the input waveguide 4, along the other propagation axis 40 ′ offset relative to the axis of propagation 40 along the flow axis 20: this other input waveguide 4 ′ therefore allows a treatment of the fluid medium flowing in the flow tube 2 at a second remote treatment zone along the flow axis 20 with respect to a first fluid medium treatment zone associated with the input waveguide 4.
• a rectilinear portion 81 ′ extending parallel to the axis of propagation 40 and to the other axis of propagation 40 ’, between the latter two, and
• junction portion 82 ′ in the general shape of “Y”, adapted to connect said straight portion 81 ′ to the input waveguide 4 on the one hand and to the other input waveguide 4 ′ on the other hand.
• the straight portion 81 has a rectangular section identical to that of the input waveguide 4 and the other input waveguide 4 ', having the same large dimension GD and the same small PD dimension.
• the upstream waveguide 8 ' is adapted to be connected, at one end 81 1' of the straight portion 81 ', to a microwave generator (not shown in FIG. 13): microwaves thus introduced into this upstream waveguide propagate along the rectilinear portion 81 ′ then are separated into two:
• a first part of the microwaves is introduced into the input waveguide 4 and propagates along the propagation axis 40, and comes into contact with the fluid medium at the level of the first treatment zone 400, and
• a second part of the microwaves is introduced into the other input waveguide 4 ′ and propagates along the other propagation axis 40 ′, and comes into contact with the fluid medium at the level of the second zone treatment 400 '.
• microwave reactor 1 ′ is here placed on a support base 7 ′, the geometry of which is in particular adapted to that of the input waveguide 4 and the upstream waveguide 8 ''
• a microwave installation 10 (partially illustrated in FIGS. 11 and 12) which comprises:
• microwave generator 9 connected to the input waveguide 4 via an upstream waveguide 8;
• a flow system 6 connected to the flow tube 2 upstream and downstream in order to allow a flow of the fluid medium inside the flow tube 2.
• This delivery system 6 comprises:
• a device suitable for circulating the fluid medium in the first and second pipes 61, 62, such as for example a pump, a turbine, a piston device, etc.
• the flow system 6 is activated to flow a fluid medium inside the flow tube 2 and the microwave generator 9 is activated to generate microwaves which are guided up to the input waveguide 4 and which pass through the input window 37 to irradiate and continuously treat the fluid medium flowing in the flow tube 2.
• a single microwave generator can be used for the propagation of microwaves in the input waveguide 4 and in the other input waveguide 4 ', via of the upstream waveguide 8 '.
• Figures 4 to 6 represent the amplitude of the electric field (or microwave field) calculated in the microwave reactor 1 and in the medium fluid for a fluid medium equivalent to mineral water and with a microwave frequency of 915 MHz.
• Figure 5 corresponds to Figure 4 but with a linear scale, to highlight that almost no more waves remain at the ends of the flow tube.
• Figure 6 shows that the electric field is rather uniform in the section of the flow tube 2 and is absorbed around its entire periphery.

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• 2018
  • 2018-11-21 FR FR1871666A patent/FR3088797B1/fr active Active
• 2019
  • 2019-11-21 CN CN201980076880.1A patent/CN113170547B/zh active Active
  • 2019-11-21 US US17/295,622 patent/US12101867B2/en active Active
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  • 2019-11-21 EP EP19839638.4A patent/EP3884736A1/de active Pending
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