WO2020016307A1

WO2020016307A1 - Flow microwave heater

Info

Publication number: WO2020016307A1
Application number: PCT/EP2019/069261
Authority: WO
Inventors: Heimo Kotzian
Original assignee: Anton Paar Gmbh
Priority date: 2018-07-18
Filing date: 2019-07-17
Publication date: 2020-01-23
Also published as: AT521497B1; AT521497A4; DE112019003616A5

Abstract

A description is given of a device (100-1200) for microwave application for a liquid sample flowing through, wherein the device comprises: a hollow conductor (101), which is designed for guiding a microwave (103) inside, in particular in the longitudinal direction (105) of the hollow conductor (101); a sample guiding tube (107) with a plurality of windings (109_1, 109_2) within the hollow conductor, wherein at least one of the windings (109_1, 109_2) has at least one portion (111) along which its curvature changes, in particular by between 50% and 200%.

Description

Flow Microwave Heating

Ge bjet de r_E rfi ndu M

The present invention relates to a device for microwave use for a liquid sample in flow and further relates to a method for heating a liquid sample in flow,

background

Microwave devices include a power oscillator (e.g. magnetron), which is used to generate an electromagnetic wave in the

Microwave length range is formed. The microwaves are absorbed by different materials depending on their molecular structure, which leads to the heating of the materials.

Flow reactors with a microwave generator for heating liquid samples are known as such. Straight or curved tubes are introduced in multi-mode or mono-mode applicators or in a waveguide. The sample to be heated is passed through the pipes.

The conventional flow-through microwave heaters, however, have an unsatisfactory efficiency and an insufficient heating power or a high proportion of reflected microwave energy.

It is therefore an object of the present invention to provide a device for microwave use for a liquid sample in flow and a corresponding method, the liquid sample being able to be heated effectively by the microwave without significant reflections. The object is solved by the subject matter of the independent claims. The dependent claims specify specific embodiments of the present invention.

Z iLsa m m e n f a s s u n g J_e r_E rfin d unq

According to one embodiment of the present invention, there is provided an apparatus for microwell application for a liquid sample in

Flow, the device comprising: a waveguide which is designed for guiding a microwave inside, in particular in the longitudinal direction of the waveguide; a sample guide tube with a plurality of turns within the waveguide, at least one of the turns having at least one section along which the curvature changes, in particular by between 50% and 200%.

The device can be used to generate the microwave e.g. comprise a magnetron. The microwave can extend along the longitudinal direction of the waveguide e.g. Spread out in such a way that the electrical field direction is oriented essentially perpendicular to the direction of propagation of the microwave, in particular perpendicular to the longitudinal direction of the waveguide. The waveguide can be a metal tube, the microwave being guided in the interior of the metal tube. The waveguide can e.g. have a rectangular, circular or oval cross-section, the microwave being perpendicular to the

Cross section can spread.

The (flexible or rigid) sample guide tube (for example with a circular or oval cross-sectional shape) can be designed to guide or let the liquid sample flow inside. The device can be designed to heat the flowing sample by means of an energy transfer from the microwave to the sample. The sample guide tube can have several sections of similar or different shapes. The sample guide tube, in particular their several sections can be designed depending on, for example, a cross-sectional shape of the waveguide and in particular a distribution of the electrical field directions within the waveguide. In particular, the sample guide tube can be designed to have a larger proportion of sections which are oriented essentially tangentially to the electrical field direction than sections which are in the

Are oriented substantially perpendicular to the electrical field direction. This can improve a dielectric coupling between the microwave and the sample to be heated, which flows within the sample guide tube. This can lead to effective heating of the sample.

Depending on a position within the waveguide, the electrical field direction can change (viewed at a certain fixed point in time). Along a longitudinal axis or central axis of the waveguide, the electric field can e.g. in a certain direction, e.g. show the Z-direction. The cross section of the waveguide can, for example, lie in a Z-Y plane, the direction of propagation of the microwave (and longitudinal axis of the waveguide) can lie along the X axis. Of course, the one claimed

Subject not limited to these definitions of Cartesian directions. The Cartesian coordinate system can be redefined as required. However, the definition given above facilitates e.g.

Reference to a direction of propagation of the microwile (e.g. the X-axis) or a reference to a cross-section (e.g. the Z-Y plane) of the waveguide. Spaced from the longitudinal axis (e.g. X-axis) of the waveguide (in particular parallel to the direction of propagation of the microwave), the electrical field can have components within the Z-Y plane,

in particular, do not exclusively have a component in the Z direction, but can also have a component in the Y direction. The sample guide tube can be designed to conform at least in sections to the direction of the electric field, for example in sections by the sample guide tube following the changing directions of the electric field.

Each of the plurality of turns can e.g. run essentially in a plane which is substantially perpendicular to the direction of propagation of the microwave. If at least one of the windings has at least one section along which the curvature changes, the proportion of sections of the sample guide tube which have a small angle (for example less than 50 °, less than 30 °, less than 10 °) between tangents can advantageously be present the winding and electrical field direction have to be larger (in particular by 50%, 70%, 80%) than a proportion of sections of the sample guide tube which have a relatively large angle (for example greater than 70 °, greater than 80 °, but less than or equal to 90 °) between tangent to the

Include turn and electrical field direction. A heating effectiveness can thus be improved by the dielectric coupling between the microwave and the sample to be heated. The curvature denotes a local deviation in the shape of the

Sample guide tube (or the winding) from a straight line. For each of the plurality of turns, the curvature (e.g. quantified by the amount of curvature) can be understood as the curvature of the curve which lies within the plane which is essentially defined by the

considered turn is spanned. For example, a circular arc with a fixed radius has the same curvature everywhere. For example, the curvature of a straight line is zero everywhere. The smaller the radius of the circle, which nestles locally on one of the turns, the greater its curvature. The reciprocal of the radius of the circle, for example, can be assumed as a measure of the curvature, which is locally attached to the winding of the sample guide tube under consideration. The curvature can be considered the derivative of the Center angle can be understood according to the length of the circular arc. The

The reciprocal of the curvature is called the radius of curvature, this radius defining a circle of curvature that best approximates the winding of the sample guide tube under consideration at the point under consideration. Depending on which side of the winding under consideration the

Tube is the center of the curvature (the center of the best-fitting circle), the curvature can be interpreted as positive or negative.

A change in the curvature can e.g. present if that

Measure of curvature e.g. changes from a value 0 to a positive value or to a negative value if the degree of curvature changes from a positive or a negative to a value 0 or if e.g. the amount of curvature changes from a positive to a negative value.

A change in the curvature can e.g. present if that

Measure of curvature e.g. changes from a positive value to a larger or smaller positive value or if the degree of curvature changes e.g. changes from a negative value to a larger or smaller negative value. Due to the change in the curvature of the turn, the change in the direction of the electric field can be taken into account.

At least one or more of the turns of the sample guide tube can both have sections with a positive (or negative)

Measure of curvature as well as sections with a vanishing

Measure of curvature and / or sections with a negative (positive)

Have degree of curvature. The length of these sections can be selected in such a way that the turns predominantly correspond to the

Nestle directions of the electrical field component. This can improve a dielectric coupling for energy transfer from the microwave to the sample to be heated. The shape of the sample guide tube can be in Dependency in particular of the directions of the electric field (for example, in a cross section of the waveguide) can be selected or defined.

According to one embodiment of the present invention, the device is designed such that at least one of the windings points

in particular centered along an X direction, the longitudinal axis of the waveguide (i.e. a center point of the turn lies on the longitudinal axis) and an extension in a Z direction, along which a direction of the

Electric field of the microwile points on the longitudinal axis, which is between 1.5 and 4 times as large as an extension perpendicular to it, in particular in the Y direction.

The longitudinal axis of the waveguide can in particular in the direction of

Direction of propagation of the microwave. At points along the longitudinal axis of the waveguide, the electric field can e.g. have only one component in the Z direction. The electric field can

Have mirror symmetry, wherein a mirror plane can be defined by the ZX plane. The further a point under consideration is spaced from the longitudinal axis in the Z direction, the larger a component of the electric field in the Y direction can be. In particular, the greater the distance of the point under consideration from the longitudinal axis of the waveguide, both in the Z direction and in the Y direction, the greater a component in the Y direction of the electric field. The extent of a turn in question in the Z direction can be defined, for example, by a difference in the Z coordinates of an outer edge of the turn in question. The greater the extension in the Z direction of a winding under consideration, the greater the proportion of sections of the winding under consideration which enclose a small angle with the electric field. If the extension of the turn in the Y direction is small relative to the extension in the Z direction, only a small proportion of the sections of the turn under consideration are included the electrical field an angle that is close to 90 °, this can improve the coupling of microwave energy into the sample,

According to one embodiment of the present invention, the

Sample guide tube designed in such a way that at least one of the turns has an oval shape with two opposite straight sections, in particular running parallel to the Z-axis, and with two opposite outwardly curved sections, with a length of all straight sections of the turn in particular between 0.5- and 5 times, furthermore in particular between 1.5 and 2.5 times, as long as the length of all sections of the turn which are curved outwards,

A winding with an oval shape can have two opposite sections with curvature 0 and two opposite sections with positive or negative curvature. The straight sections can be in

Aligned essentially parallel to the electric field, with deviations being greater the farther the point under consideration is in the Z direction or the Y direction from the longitudinal axis of the waveguide. If the sum of the length of all straight sections of a winding under consideration is in particular greater than a sum of the length of all sections of the winding that bulge outwards, a dielectric coupling of the microwave into the sample to be heated can be improved.

According to one embodiment of the present invention, the

Sample guide tube formed such that at least one of the windings has an indented oval shape with two opposite inwardly indented sections and two opposite outwardly curved sections, with a length of all inwards

indented sections of the turn, in particular between 0.5 and 5 times, furthermore in particular between 1.5 and 2.5 times, is as long as the length of all sections of the turn that are curved outwards, According to this embodiment, a winding under consideration can have both two sections with negative (positive) curvature and two sections with positive (negative) curvature. Through the inside

indented sections, a change in direction of the electric field, which may be present along the Z direction, can be modeled.

According to one embodiment of the present invention, the

Sample guide tube designed such that the winding essentially has mirror symmetry with respect to a longitudinal axis, in particular parallel to the Z axis, the winding and / or essentially point symmetry with respect to one

Has intersection of the longitudinal axis of the waveguide with a plane of the turn.

A mirror symmetry of the sample guide tube can be used as a mirror plane e.g. have the Z-X plane. In embodiments, a single turn may be tilted from the Z-Y direction, especially if a spiral sample guide tube is provided. In this case, only approximately mirror symmetry needs to be present. A

mirror-symmetrical winding can be easily produced. The

Sample guide tube or at least one of the turns of the

Sample tube can be essentially a similar or the same

Have symmetry like the electric field within the waveguide. Any existing point symmetry can also be a production

simplify. Furthermore, the change in the directions of the electric field can be taken better into account.

According to one embodiment of the present invention,

Quotient of an integral of an amount of a scalar product of the electric field and a tangential vector of at least one of the Turns taken along a circumference of the turn and an integral of an amount of the electric field taken along the circumference of the turn

between 0.4 and 0.7.

The integral can be understood as a circular integral around one of the turns. The greater the quotient, the better dielectric coupling can take place between the microwave and the sample to be heated. The value of the quotient is determined by the shape of the winding under consideration and by the field profile of the electrical field within the waveguide. The quotient can refer to a fixed point in time. The point in time can in particular mean the point in time at which the electric field is at a maximum at the point of intersection between the longitudinal axis of the waveguide and the plane spanned by the winding. An effective dielectric coupling can thus be achieved.

According to one embodiment of the present invention, the device is designed such that a first group of the plurality of turns is designed and aligned primarily for the dielectric coupling of the microwave and a second group of the plurality of turns is designed and aligned primarily for the inductive coupling of the microwave,

A dielectric coupling of the microwave can be used in particular for heating non-conductive samples, with the continuity of the electric field strength or in particular the continuity of the

Tangential component of the electric field strength can be exploited from an area outside the sample to an area inside the sample. The tangential component of the electric field strength does not decrease at the interface between the fluid or the sample or the exterior of the sample guide tube by the ratio of the dielectric constant (in contrast to the normal component). Even with samples with a high dielectric constant, an increased power input from the microwave to the sample can thus take place.

In order to achieve a dielectric coupling, certain criteria of the shape of the sample guide tube or a winding thereof can be met. For example, large portions of the pipe sections can be perpendicular in one

Round waveguides run, in particular parallel to the Z direction, i.e. parallel to the direction of the electric field along the longitudinal axis of the waveguide. Preferably, at least one of the turns of the sample guide tube may have a slightly oval shape, in other embodiments, at least one turn of the sample guide tube may have an oval with a "pinch", i.e., two opposing outwardly curved sections and two opposite inwardly curved sections.

The inductive coupling of the microwave can be advantageous or provided in particular for conductive samples. The energy can be coupled into the sample by coupling the magnetic field (which is in particular perpendicular to the electrical field).

According to one embodiment, the device can thus provide both dielectric coupling and inductive coupling, in particular specifically in sections provided especially for this, so that both conductive and non-conductive samples can be effectively heated or heated with the aid of the device.

According to this embodiment, the device can be designed such that a sum of lengths of substantially tangential to the

Electric field of the microwave aligned sections of the first group of turns gives a first sum and a sum of lengths of substantially tangential to the electric field of the microwave Sections of the second group of turns results in a second sum, the first sum being between 1.1 and 10 times the second sum. If the first sum is greater than the second sum, the first group of turns can be effective for dielectric coupling and the second group can effectively be suitable for inductive coupling.

Electric field of the microwave aligned sections of the first group of turns gives a first sum and a sum of lengths of a second group of turns gives a second sum, bordering surfaces that are aligned substantially normal to the magnetic field of the microwave.

The second group of turns can be used in particular for heating conductive samples. For this purpose, a flux of the magnetic field through a surface spanned by the windings can be relatively large in order to achieve inductive coupling. The degree of coupling for a turn can be influenced via the effective area normal to the magnetic field, e.g. by tilting around the Y axis. This can allow an individual setting of the power input across the winding levels.

A (e.g. circular) turn can e.g. B. lie in the Y-Z plane in order to achieve maximum coupling with the H-field IMormal component.

According to one embodiment of the present invention, the

Sample guide tube formed such that one or more of the

Windings of the first group have an oval and / or oval indented shape and their longitudinal directions are aligned parallel to the Z direction, and / or that one or more of the windings of the second group have an essentially circular shape. The windings with an essentially circular shape can be oriented such that the circle lies, for example, in a ZY plane or XZ plane. In other embodiments, the circle or the windings with a circular shape can lie essentially parallel to the ZY plane. An inductive coupling can e.g. B. can be achieved by the corresponding windings provided for inductive coupling have a shape so that the magnetic field at a large angle to the edges of the sample guide tube

Surfaces of the turn (e.g. greater than 60 °, greater than 70 °, greater than 80 °).

A circular shape can be advantageous since the magnetic field can be essentially circular (e.g. centered around the Z axis). The magnetic field can be essentially normal to the circular windings or the surfaces spanned by them.

According to one embodiment of the present invention, the

Device further on: a holder system which is essentially transparent to the microwave and is designed to hold the plurality of turns in a predetermined shape, in particular interchangeably,

the mounting system in particular having at least one plate

Has through holes through which the sample guide tube is guided.

The mounting system can be constructed from various materials, which, however, advantageously do not weaken or absorb much of the microwave. A mounting system can be provided, in particular, for flexible windings, which must be suitably supported in order to assume a certain predefined shape. If at least one plate, in particular a plurality of plates, which are spaced apart in parallel along the direction of propagation of the microwave, the different turns of the sample guide tube can be held in a simple and effective manner. For example, three mounting plates can be provided be, which are spaced in the Z direction and each at least in

Are aligned substantially parallel to the X-Y plane. With this e.g. an oval shape or a pinched oval shape of one or more turns are easily formed. Two of the plates can have slots or holes on both longitudinal edges, into which e.g. a hose can be inserted. Each of the slots can e.g. clamp a hose section or several hose sections arranged one above the other in the slot direction. Thus e.g. a helical section of the sample guide tube consisting of several turns lying in one plane can also be formed. The mounting system including the

Sample guide tube can be removed from the waveguide. A flexible tubing as an embodiment of the sample guide tube can be removed from the support system around which

For example, to replace the hose with a new hose or to change the shape of the hose.

According to one embodiment of the present invention, the device is designed in such a way that at least a part of the plurality of turns within the waveguide can be held in at least two orientations, in particular snap-in, which in particular by 90 ° around the

Longitudinal axis of the waveguide are twisted. If multiple orientations of the plurality of turns are possible, e.g. both conductive samples and non-conductive samples are effectively heated after the

Windings have been aligned accordingly, e.g. in particular to support dielectric coupling or inductive coupling.

According to one embodiment of the present invention, the plurality of turns has at least two turns which lie essentially in one plane. This allows a section of the sample guide tube to be a

Have a screw shape in order to increase the volume or the amount of the sample to be heated. According to one embodiment of the present invention, the plurality of turns has at least two turns, which lie essentially in different planes spaced apart from one another along the longitudinal direction of the waveguide, in particular further than 1/8 of the wavelength, which are essentially perpendicular or tilted to the longitudinal direction of the Waveguide are aligned. Windings spaced apart from one another can be connected to one another, so that at least sections of the sample guide tube can be formed spirally.

According to one embodiment of the present invention, all of the windings have the same shape with the same or with changing, in particular fan-like, orientation. If all turns are in the same shape, production is simplified. If the turns have different orientations, both a dielectric and an inductive coupling of the microwave into the sample can be supported.

At least one of the windings can be designed as a flexible hose, in particular made of typical microwave-transparent plastics, in particular having PTFE or PE. This can be used to support conventionally available materials.

According to one embodiment of the present invention, the waveguide is designed to be pressure-resistant and / or the waveguide has a circular or oval or rectangular cross-sectional shape and / or the waveguide is formed from metal. Thus, the sample can be heated, for example, under high pressure within the sample guide tube, with an essentially identical pressure also prevailing within the waveguide, for example. According to one embodiment of the present invention, the device is designed such that the microwave has an H wave or a transversely electrical (TE) wave within the waveguide (note: an H wave corresponds to a TE wave), the electric field in the

Points essentially perpendicular to the direction of propagation of the microwave, in particular lies in the Y-Z plane and in particular has no component in the X direction, the magnetic field in particular essentially lying in the X-Y plane. This means that conventionally generated microwaves can be used, e.g. magnetron, solid state generator or similar.

According to one embodiment of the present invention, the

Device further comprises a microwave generator for generating the microwave,

wherein the microwave generator is arranged to couple the microwave into the waveguide via a first end face of the waveguide along the X direction. The microwave generator can e.g. comprise a magnetron which has an antenna which e.g. is aligned along the direction of the electric field on the longitudinal axis of the waveguide.

According to one embodiment of the present invention, the

Device further comprises a microwave adapter that between the

Microwave generator and the waveguide is arranged and has a rectangular shape to couple the microwave into the waveguide. The

Dimensions of the microwave adapter can be selected in order to achieve a desired microwave mode within the waveguide. The microwave can be coupled into the waveguide from a microwave generator directly or via the microwave adapter (also called a launcher). According to one embodiment of the present invention, the device is designed such that the sample is from a second end of the

Waveguide can be introduced into the sample guide tube to initially, in particular in the direction of upstream windings, in the direction of the

Microwave generator to flow to afterwards, especially in

Reverse current turns to flow towards the second end where the sample exits.

It is also to increase the temperature of such arrangements

it is desirable to be able to carry out the heating under high pressures. On the one hand, this can be done with tubes carrying pressure-resistant samples.

Borosilicate glass, ceramics are used. The waveguide can e.g.

have a cylindrical shape, e.g. can have a special compressive strength. It can be used for heating under high pressures

on the other hand, it is possible to put both the waveguide and the sample-carrying tube under the same, increased pressure. With this e.g. also known microwave-transparent plastics, such as PTFE

(Trade name eg "Teflon") can be used. Microwave-transparent holding structures can be used on which the tubes (the sample guide tube) can be wound. The tubes can be wound in different planes or in one plane. The device can be arranged in a targeted manner of microwave-transparent fluid sections on the source side and the cold sections on the end of the device If the sample is still cold, a relatively low electric field strength is required for heating due to the high dielectric constant, whereas with a hotter sample the dielectric constant decreases, which means that higher electric field strengths are required to heat the sample. Therefore, the sample can be introduced into the sample guide tube from the second end of the waveguide, where relative lower electric field strengths prevail than closer to the first end of the waveguide.

The shapes of the sample guide tube described above can be adapted to various shapes of the waveguide. If the waveguide e.g. cylindrical shape, can be without a launcher or without one

Microwave adapter the microwave, which is generated by the magnetron, can be coupled directly into the waveguide. A more compact, achievable version is advantageous. A detailed analysis of the

The temperature properties of the arrangement show that the heating for the coupling into conductive samples changes drastically. For conductive samples, the energy input via the magnetic field is more important, i.e. the coupling is inductive. For conductive samples, this leads to an additional or alternative adaptation of the geometry in order not only to be able to couple dielectrically (via the electrical field) but also inductively via the magnetic field component. Depending on the conductivity of the sample, the orientation of the turns of the

Sample guide tube can be set or executed. This also creates a flow reactor with inductive heating of a conductive sample. This can be achieved, for example, by rotating the sample guide tube through 90 °, which was initially designed for dielectric coupling.

In this way, essential sections of the sample guide tube can no longer be tangent to the electric field, but to planes formed by the windings, normal to the magnetic field. In particular, the

Sample guide tube using the support system in certain

Locking positions are held in an assigned orientation in order to alternatively or selectively heat both conductive samples and non-conductive samples in each case via inductive coupling or dielectric coupling. For a selection of sample materials, information can be provided for a user as to which orientation of the sample guide tube is best suited for the particular sample for heating. This orientation can then be set by the user before the sample is heated with the device. An adjustment can be provided so that the device supports both inductive and dielectric heating. This orientation can be defined, for example, as an intermediate stage between an orientation provided for inductive coupling and an orientation provided for dielectric coupling.

It should be understood that features individually, or in any combination, described, applied, or used in connection with an apparatus for microwave application for a liquid sample in flow, likewise, individually or in any combination, for a method of microwave application for a liquid sample can be applied in flow and vice versa, according to embodiments of the present invention,

According to one embodiment of the present invention, there is provided a method for the use of microwaves for a liquid sample in flow, the method comprising: guiding a microwave inside a waveguide, in particular along a longitudinal direction of the waveguide; Guiding the sample within a sample guide tube with a plurality of turns within the waveguide, at least one of the turns having at least one section along which the curvature changes, in particular by between 50% and 200%.

Further advantages and features of the present invention result from the following exemplary description of some embodiments, to which the invention is not restricted. BRIEF DESCRIPTION OF THE DRAWINGS

1 illustrates, in a schematic perspective illustration, a device for microwave application for a liquid sample according to an embodiment of the present invention;

2A, 2B illustrate properties of the electric field

Interfaces;

3 illustrates part of an apparatus for microwave application according to an embodiment of the present invention;

4 illustrates an apparatus for microwave application according to an embodiment of the present invention;

5 illustrates an apparatus for microwave application according to an embodiment of the present invention;

6 illustrates an apparatus for microwave application according to an embodiment of the present invention;

7 illustrates part of an apparatus for microwave application according to an embodiment of the present invention;

8 illustrates a support system with a sample guide tube for a microwave application device according to an embodiment of the present invention;

Fig. 9 illustrates the mounting system inserted in a waveguide, which is illustrated in Fig. 8; FIGS. 10A and 10B illustrate parts of devices for

Microwave application according to an embodiment of the present invention;

11 illustrates a sample tube of a microwave application device according to an embodiment of the present invention; and

12 illustrates an apparatus for microwave application according to a still further embodiment of the present invention,

DETAILED DESCRIPTION OF EMBODIMENTS

Similar elements in structure and / or function

Embodiments are designated in the various figures with reference numerals, which differ only in the first digit. A description of an element not described in detail in a specific embodiment can be found in the description of another embodiment.

The device 100 for microwave use for a liquid sample in flow, illustrated in a perspective schematic illustration in FIG. 1, comprises a waveguide 101, which is illustrated only schematically and which, in particular in the longitudinal direction 105, guides a microwave 103 (eg supplied via an adapter 137) of the waveguide 101 is formed. The longitudinal direction 105 coincides with an X axis of an XYZ coordinate system. The device 100 further comprises a sample guide tube 107 with a plurality of turns 109_1, 109_2 within the waveguide 101. The waveguide 101 is only illustrated schematically, for example it may have a circular cross section 102. 21

At least one of the turns 109__1, 109 _" 2 has a section, in particular a section 111, along which the curvature of the corresponding turn 109 _" 1, 102__2 changes. The turns 109 _“ 1, 109_2 are connected to one another, so that the sample is passed through the turn 109_J. and flows through the turn 109_2. Inlet and outlet openings for the sample are not illustrated in Figure 1 for clarity. In the embodiment illustrated in FIG. 1, the turns 109_1, 109_2 lie in a plane which is perpendicular to the

Longitudinal direction 105 and thus also perpendicular to the

Direction of propagation 103 of the microwave.

The winding 109 _" 1 has an indented oval shape with two

opposite inwardly indented sections 115, 117 and two opposite outwardly curved sections 119, 121. The sum of the length of all sections 115, 117 indented inwards is greater than the length of all sections 119, 121 that bulge outwards. An extent az of the turn 109_1 along the Z direction is approximately three times as large as an extent ay along the turn 109__1 the Y direction. The X-Z plane forms a mirror plane for each of the windings 109_1, 109_2. The origin of the coordinate system X, Y, Z also forms

Point symmetry center for each of the turns 109_1, 109_2.

1, electric field vectors are illustrated as arrows 113. As can be seen from FIG. 1, the electric field at the longitudinal axis 105 of the

Waveguide 101 in the Z direction. As can be seen from FIG. 1, the electric field 113 for the inwardly indented sections 115, 117 of the turns is essentially parallel to these sections of the

Turns. If a quotient of an integral of an amount of a scalar product of the electric field 113 and a tangential vector to at least one of the turns along a circumference of the respective Winding 109_1, 109_2 and an integra! of an amount of the electric field 113 along the circumference of the respective winding 109_1, 109_2, an amount between 0.4 and 0.7 is obtained. Thus, a large proportion of sections of the respective winding lie little different from a direction of the electric field, which improves a dielectric coupling between the electric field and the sample guided in the sample guide tube 107.

FIGS. 2A and 2B illustrate properties of the electric field E at the transition at an interface 204 with a material

Dielectric constant ei ZU a material with a dielectric constant ti for the tangential component (denoted by E _t ) and the

Normal component (denoted by E ") in Figs. 2A and 2B. As from fig. 2A and 2B, the tangential component of the electric field is continuous at the transition between the two materials, whereas the normal component is dependent on the ratio of the

Dielectric constant is changed. As a rule, a sample to be heated has a higher electricity constant than the vacuum. A

Energy coupling via the normal component of the electrical field would therefore only take place via a correspondingly weakened electrical field.

In contrast, a weakening of the field can be avoided if the turns 109_1, 109__2 are essentially aligned along the electrical field, so that the tangential component of the electrical field at the interface is responsible for the energy transfer.

As can be seen from FIG. 1, the sections 115, 117 of the windings 109_1, 109_2 essentially conform to the course of the electric field 113. This enables effective energy coupling via dielectric coupling. FIG. 3 illustrates part of a device 300 for microwave application according to an embodiment of the present invention, only ¹ A of the overall device being illustrated. Windings 309_1, 309_2 have a similar shape to the windings 109_1, 109_2, which are illustrated in FIG. 1. In contrast to the embodiment illustrated in FIG. 1, however, the device 300 comprises a plurality of further pairs of turns 309 _“ 3, 3Q9_4 _< 309_n-1, 309__n, where n can be, for example, between 5 and 50. The

Pairs of turns are each spaced along the longitudinal axis 305 (i.e., X-axis), the distance d advantageously being greater than 1/8 of the wavelength of the microwave 303. Successive pairs of turns can be connected. For example, the inner turns (denoted with even indices) of subsequent pairs could be connected and the respective outer turns (denoted with odd numbers) could also be connected to one another. The sample could flow through the inner (or outer) turns on the way out of the sample and the sample could flow through the outer (inner) turns on the way back of the sample. In other embodiments, the inner and outer turns of each pair are connected together. The device illustrated in FIG. 3 further comprises a mounting system 319, which comprises at least one perforated plate 321. The windings 309 are guided through holes 322 in the plate and are held by the boundary surfaces of the holes 322 in order to achieve the desired shape of the windings 309. A second plate 325 in turn has holes 327 through which the turns 309 are passed, thereby forcing the turns formed of flexible material into a certain shape.

Fig. 4 illustrates a partially cut waveguide with a

Sample guide tube 407 of an apparatus 400 for microwave application according to an embodiment of the present invention. The device 400 illustrated in FIG. 4 also comprises a mounting system 419, which consists of a first plate 423, a second plate 425 and a third 24

Plate 427 is formed. The plates 423, 425, 427 are spaced apart from one another and parallel to one another in the Z direction, the plates being aligned parallel to the X-Y plane. In contrast to the plates 323, 325, which are illustrated in Fig. 3, the upper and lower plates 423, 427 each have slots 429 on their two longitudinal edges, into each of which a tube section of a turn, e.g. 409_1 are laid. The central plate 425 does not have respective slot-shaped recesses 431 at the respective longitudinal side edges, but rather in a central region, into which two sections of each turn 409 are inserted. The plate 425 is shown partially cut away, only one half being illustrated and the front half being only indicated transparently.

The turns 409 of the device 400 and also the turns 309 of the device 300 have the same shape and also have the same orientation.

As can be seen from FIG. 4, the waveguide 401 has a cylindrical shape, the cylinder axis (i.e. longitudinal axis) coinciding with the X axis and at the same time with the direction of propagation 403 of the microwave. A flange 433 is placed on a first end face 435 of the waveguide and attached for fastening the waveguide 401 e.g. on a microwave generator or in particular on a microwave adapter 537, as e.g. 5 is illustrated in a perspective view. The sample is carried into the sample guide tube 407 from a second end face 439 of the waveguide 401

Windings 409 introduced and initially flows towards the second end face 435. In certain embodiments, the sample can be heated on the outward and return path and can flow back on the way back towards the first end face 439, from where it can leave the device 400. The device 500 illustrated in FIG. 5 comprises a microwave generator 541, which is cooled by a fan 543. The

Microwave generator 541 is designed, a microwave e.g. To couple into the microwave adapter 537 via an antenna. From there, the microwave is coupled into the waveguide 501 in such a way that the microwave progresses along the longitudinal axis 503 (X axis) of the waveguide 501. The microwave releases energy into the sample, which flows in the turns 509 of the sample guide tube 507. The microwave generator 541 couples the microwave into the interior of the waveguide via the first end face 535 of the waveguide.

FIG. 6 also illustrates a part of the device 500 illustrated in FIG. 5, in particular the waveguide 501 and also an antenna 545 of the

Microwave generator 541. The antenna 545 emits a microwave 503, the electric field 513 of which is aligned parallel to the antenna 545.

The illustrated in Fig. 7 device 700 to the microwave application is illustrated only to ^1/4, and includes a waveguide 701 in which a

Sample guide tube 707 with a variety of along the

Direction of propagation 703 of the microwave spaced turns 709__1, 709_2, 709 4 is arranged. A plurality of four turns in each case is arranged in a plane perpendicular to the direction of propagation 703 and spaced apart from one another in the direction of propagation 703 within the waveguide. The windings 709 include two opposite straight sections (only one of which is illustrated in FIG. 7) 747 and two opposite outwardly curved sections 749 (only half of which is shown). The straight sections 747 are aligned parallel to the Z axis, ie parallel to the direction of the electric field on the longitudinal axis 703 of the waveguide 701. Windings in one plane can be connected to one another or at least partially windings can be connected to one another in one plane. turns two successive levels can be connected together to allow sample flow through all turns 709_1

709__n to enable

FIG. 8 illustrates a holder system 819 together with windings 809 of a sample guide tube 807, the sample guide tube with the holder system being removed from the waveguide. FIG. 9 illustrates the holder system 819 of FIG. 8 after it has been inserted into the waveguide 901. The holder system 919, like the holder system 419 of FIG. 4, has three plates 923, 925, 927, which have slots through which sections of the sample guide tube 907 are guided,

FIGS. 10A, 10B illustrate a first turn group 1051 and a second turn group 1053 of the sample guide tube 1007, the first group 1051 being designed and oriented primarily for dielectric coupling of the microwave, and the second group 1053 of the plurality of turns 1009 mainly for inductively coupling the Microwave is trained and aligned. The first group 1051 of turns has a greatest orientation in the Z direction, whereas the second group 1053 of turns has a greatest extent in the Y direction. A form of

Turns of the first group and the second group is equal to that

However, orientation is rotated by 90 ° relative to one another. This can support a dielectric and also an inductive coupling of the microwave energy for the different winding groups,

FIG. 11 illustrates a sample guide tube 1107 with turns 1109_1 to 1109_n arranged in a fan-like manner, the orientation changing

successive turns continuously changes. FIG. 12 illustrates a device 1200 for microwave use, wherein one or more turns of a first group 1151 have an oval shape and their longitudinal directions are aligned parallel to the Z direction.

One or more of the windings of a second group 1153 (with two rows of circles) essentially have a circular shape. The circles of the second group 1153 lie parallel to the Z-Y plane.

A design exclusively with turns for inductive coupling is also provided, which is suitable for applicators in which only conductive samples are processed.

The sample enters the sample guide tube along direction 1155, passes through a first series of circles on the way out through the waveguide 1101, becomes the first turn of a second via a connection 1156

Guided circular row, then runs through the second circular row on the way back through the waveguide 1101 to exit along direction 1157.

Features illustrated or described in the various embodiments may be combined with other embodiments. The frequency of the microwave can be between 1 GHz and 200 GHz. A cylindrical waveguide can e.g. have a diameter of between 50 mm and 100 mm. The distance between turns can meet the condition that it is greater than 1/8 of the wavelength of the microwave. The

Sample guide tube may have a screw shape, a screw shape, or a combination thereof.

Claims

Patent claims

1. A device (100-1200) for microwave application for a liquid sample in flow, the device comprising;

a waveguide (101) for guiding a microwave (103) in the

Inside, in particular in the longitudinal direction (105) of the waveguide (101),

is trained;

a sample guide tube (107) having a plurality of turns

(109__1, 109 2) within the waveguide,

wherein at least one of the turns (109_1, 109_2) has at least one section (111) along which the curvature changes, in particular by between 50% and 200%.

2. Device according to the preceding claim, wherein at least one of the windings (109_1, 109_2) is centered on a longitudinal axis (105) of the waveguide, in particular along an x direction, and an extent (az) in a z direction one direction of

Electric field (113) of the microwave (103) on the longitudinal axis (1 05), which is between 1.5 and 4 may as large as an extension (ay) perpendicular to it, in particular in the y direction.

3. A device according to any one of the preceding claims, wherein at least one of the windings _{(709. 1,)} an oval shape with two opposite straight, in particular parallel to the z-axis extending, portions (747) and having two opposite outwardly curved portions (749) having,

being a length; of all straight sections of the turn, in particular between 0.5 and 5 times, furthermore - in particular between 1.5 and 2.5 times, as long as the length of all sections of the turn that are curved outwards.

4, Device according to one of the preceding claims, wherein at least one of the windings (109__1) has an indented oval shape with two opposite inwardly indented sections (115, 117} and two opposite outwardly curved sections (119, 121),

wherein a length of all inwardly indented sections of the turn is in particular between 0.5 and 5 times, furthermore in particular between 1.5 and 2.5 times, as long as a length of all outwardly curved portions of the turn,

5, Device according to one of the preceding claims, wherein the

convolution

essentially mirror symmetry with respect to a longitudinal axis,

in particular parallel to the z-axis, the turn and / or

essentially point symmetry with respect to an intersection of the

Has longitudinal axis of the waveguide with a plane of the turn.

6, Device according to one of the preceding claims, wherein a

Quotient

an integral of an amount of a dot product of the electric field and a tangential vector of at least one of the turns taken along a circumference of the turn and

an integral of an amount of the electric field taken along the circumference of the turn

is between 0.4 and 0.7,

7, Device according to one of the preceding claims, wherein a first group (1051) of the plurality of turns is primarily designed and aligned for the dielectric coupling of the microwave, and

wherein a second group (1053) of the plurality of turns is designed and aligned primarily for inductive coupling of the microwave.

8. Device according to the preceding claim,

a sum of lengths of sections of the first group (1051) of turns oriented essentially tangentially to the electrical field of the micro-wave giving a first sum,

a sum of lengths of sections of the second group (1053) of turns oriented essentially tangentially to the electric field of the microwave yielding a second sum,

the first sum being between 1.1 and 10 times the second sum.

9. Device according to one of the two preceding claims,

wherein one or more of the turns of the first group (1151) have an oval and / or an oval indented shape and theirs

Longitudinal directions are aligned parallel to the z direction, and / or

one or more of the turns of the second group (1153) being substantially circular in shape.

10. The device according to one of the preceding claims, further comprising:

a holder system (319, 419) which is essentially transparent to the microwave and is designed to hold the plurality of turns in a predetermined shape, in particular in an exchangeable manner,

wherein the mounting system has in particular at least one plate (423, 425, 427) with through holes and / or with slots through which the sample guide tube is guided.

11. The device according to one of the preceding claims, wherein at least a part of the plurality of turns within the waveguide can be held in at least two orientations, in particular snap-in, which are rotated in particular by 90 ° about the longitudinal axis of the waveguide.

12. Device according to one of the preceding claims, wherein the

A plurality of turns has at least two turns (109___1, 109J2), which lie essentially in one plane.

13. Device according to one of the preceding claims, wherein the plurality of turns has at least two turns (309_1, 309__4) which are different from one another in the longitudinal direction of the waveguide, in particular further than one eighth of the wavelength,

spaced planes which are aligned substantially perpendicular or tilted to the longitudinal direction of the waveguide.

14. Device according to one of the preceding claims, wherein all of the turns have the same shape with the same or with, in particular fan-like, changing orientation.

15. The device according to any one of the preceding claims, wherein

at least one of the windings is designed as a flexible hose, in particular made of typical microwave-transparent plastics, in particular having PTFE or PE.

16. Device according to one of the preceding claims, wherein the waveguide (101) is designed to be pressure-resistant and / or has a circular or oval or rectangular cross-sectional shape and / or is formed from metal.

17. The device according to any one of the preceding claims, wherein the microwave within the waveguide has an H wave, or a transversely electrical (TE) wave (103), wherein the electric field in

points essentially perpendicular to the direction of propagation of the microwave, in particular lies in the yz plane and in particular has no component in x Direction, wherein the magnetic field is in particular essentially in the xy plane.

18, Device according to one of the preceding claims, further

showing:

a microwave generator (541) for generating the microwave, the microwave generator being arranged to couple the microwave into the waveguide (101) along the x direction via a first end face (435) of the waveguide,

19, Device according to one of the preceding claims, further

showing:

a microwave adapter (537) between the

Microwave generator (541) and the waveguide (501) is arranged and has a rectangular shape in order to couple the microwave into the waveguide

20, Device according to one of the preceding claims, wherein the sample from a second end face (439) of the waveguide (401) into the

Insertable test lead tube,

in order first to flow towards the microwave generator, in particular in forward current windings,

to then flow, particularly in reverse flow turns, towards the second end (439) where the sample exits.

21 A method of microwave application for a liquid sample in flow, the method comprising:

Guiding a microwave (103) inside a waveguide (101), in particular along a longitudinal direction (105) of the waveguide;

Guiding the sample within a sample guide tube (107) with a plurality of turns (109_1, 109_2) within the waveguide, wherein at least one of the turns (109. .1) has at least one section (111) along which the curvature changes, in particular by between 50% and 200%.