Dehydration apparatus and method

Abstract

An apparatus for dehydrating a material includes a dehydrating chamber, material holders positioned within the dehydrating chamber and configured to receive the material, microwave-generating devices configured to direct microwave radiation into the dehydrating chamber to dehydrate the material received by material holders, and a control system for controlling movement of the material holders. The control system is configured, during dehydration of the material, to translate the material holders along multiple axes selected from an x-axis, a y-axis, and a z-axis, and rotate the material holders about at least one of the three axes.

Description

DEHYDRATION APPARATUS AND METHODField

[0001] The present disclosure relates to material processing in particular to an apparatus and method for dehydrating a material such as food products.Background

[0002] Microwave dehydration systems are widely used to remove moisture from materials such as food products, biological matter, and industrial substances. In such systems, microwave energy is applied within a chamber to heat the material and drive off moisture. However, the electromagnetic field inside the chamber is typically non-uniform, resulting in regions of higher and lower field intensity. These variations cause localized hot spots and cold spots, which in turn can lead to uneven drying, overheating, or incomplete dehydration of the material.

[0003] To address this problem, some systems employ microwave sources that vary the frequency of the emitted radiation during operation. By changing frequency, the standing-wave pattern within the chamber can be altered, helping to average out field non-uniformities over time. While this technique can improve dehydration uniformity, it requires the use of solid-state or frequency-agile microwave generators, which substantially increase the complexity and cost of the equipment compared to conventional fixed-frequency magnetron systems.Summary

[0004] According to a first aspect of the disclosure, there is provided an apparatus for dehydrating a material, comprising: a dehydrating chamber; one or more material holders positioned within the dehydrating chamber and configured to receive the material; one or more microwave-generating devices configured to direct microwave radiation into the dehydrating chamber to dehydrate the material received by one or more material holders; and a control system for controlling movement of the one or more material holders and configured, during dehydration of the material, to: translate the one or more material holders along each of at least two axes selected from among three orthogonal axes consisting of: an x-axis; a y-axis; and a z- axis; and rotate the one or more material holders about at least one of the three axes.

[0005] The control system may be configured, during dehydration of the material, to translate the one or more material holders along each of the three axes.

[0006] The control system may be configured, during dehydration of the material, to translate the one or more material holders along each of the at least two axes simultaneously.

[0007] The control system may be configured, during dehydration of the material, to simultaneously: translate the one or more material holders along each of the at least two axes simultaneously; and rotate the one or more material holders about at least one of the three axes.

[0008] The control system may be configured, during dehydration of the material, to simultaneously: translate the one or more material holders along only each of the x-axis and the y-axis simultaneously; and rotate the one or more material holders about the z-axis only.

[0009] The control system may be configured, during dehydration of the material, to simultaneously: translate the one or more material holders along each of the three axes simultaneously; and rotate the one or more material holders along at least one of the three axes.

[0010] The one or more microwave-generating devices may be configured to generate frequency-invariant microwave radiation.

[0011] At least one of the one or more microwave-generating devices may be a magnetron.

[0012] The apparatus may further comprise one or more heat-generating devices configured, during dehydration of the material, to heat an interior of the dehydrating chamber.

[0013] The one or more heat-generating devices may comprise one or more adhesive heatgenerating elements provided on one or more walls of the dehydrating chamber.

[0014] The apparatus may further comprise one or more vacuum-generating devices configured, during dehydration of the material, to reduce a pressure within the dehydrating chamber.

[0015] The one or more vacuum-generating devices may be configured, during dehydration of the material, to reduce the pressure within the dehydrating chamber to a level at which moisture within the material sublimes under freeze-drying conditions.

[0016] According to a further aspect of the disclosure, there is provided a method of dehydrating a material, comprising: directing microwave radiation at the material contained in a dehydrating chamber to dehydrate the material; and during the dehydration, moving the material within the dehydrating chamber such that the material is: translated along each of at least two axesselected from among three orthogonal axes consisting of: an x-axis; a y-axis; and a z-axis; and rotated about at least one of the three axes.

[0017] Translating the material may comprise translating the material along each of the three axes.

[0018] Translating the material may comprise translating the material along each of the at least two axes simultaneously.

[0019] Moving the material may comprise simultaneously: translating the material along each of the at least two axes simultaneously; and rotating the material about at least one of the three axes.

[0020] Moving the material may comprise simultaneously: translating the one or more material holders along only each of the x-axis and the y-axis simultaneously; and rotating the one or more material holders about the z-axis only.

[0021] Moving the material may comprise simultaneously: translating the material along each of the three axes simultaneously; and rotating the material about at least one of the three axes.

[0022] Directing the microwave radiation may comprise directing the microwave radiation at the material without changing a frequency of the microwave radiation.

[0023] The method may further comprise, during the dehydration, heating an interior of the dehydrating chamber.

[0024] Heating the interior of the dehydrating chamber may comprise using one or more adhesive heat-generating elements provided on one or more walls of the dehydrating chamber.

[0025] The method may further comprise, during the dehydration, reducing a pressure within the dehydrating chamber.

[0026] Reducing the pressure may comprise reducing the pressure within the dehydrating chamber to a level at which moisture within the material sublimes under freeze-drying conditions.

[0027] The material may be a food product.

[0028] This summary does not necessarily describe the entire scope of all aspects. Other aspects, features, and advantages will be apparent to those of ordinary skill in the art upon review of the following description of specific embodiments.Drawings

[0029] Embodiments of the disclosure will now be described in detail in conjunction with the accompanying drawings of which:

[0030] FIG. 1 is a front view of a microwave dehydrator according to an embodiment of the disclosure;

[0031] FIG. 2 is a perspective view of the microwave dehydrator (without the vacuum assembly) of FIG. 1 ;

[0032] FIG. 3 is a perspective view of a motion assembly of the microwave dehydrator of FIG. 1 ;

[0033] FIG. 4 is a front view of a control cabinet for controlling the microwave dehydrator of FIG.1 , according to an embodiment of the disclosure;

[0034] FIG. 5 is a flow diagram of a method of dehydrating a material, according to an embodiment of the disclosure; and

[0035] FIG. 6 is a schematic diagram of a material holder movable within a Cartesian frame of reference, according to an embodiment of the disclosure.Detailed Description

[0036] The present disclosure seeks to provide an improved dehydrator and an improved method of dehydrating a material. While various embodiments of the disclosure are described below, the disclosure is not limited to these embodiments, and variations of these embodiments may well fall within the scope of the disclosure which is to be limited only by the appended claims.

[0037] According to some embodiments of the present disclosure, there is provided an apparatus for dehydrating a material within a chamber using microwave energy. The apparatus includes material holders positioned within the chamber to receive the material, and microwavegenerating devices configured to direct microwave radiation into the chamber. A control system is configured to control movement of the material holders during dehydration. In particular, the control system is configured to translate the material holders along each of at least two axes selected from among three orthogonal axes consisting of: an x-axis; a y-axis; and a z-axis, as well as rotate the material holders about at least one of the three axes. According to someembodiments, the material holders may be translated along each of the three axes simultaneously, and simultaneously rotated along at least one of the three axes. The material holders may therefore be moved within at least four, and up to six, degrees of freedom simultaneously.

[0038] By actively repositioning the material holders relative to the microwave field, the exposure of the material to microwave energy can be made more uniform, reducing the occurrence of localized hot or cold regions that can prevail when using fixed-frequency microwave-generating devices. As a result, the material may be dehydrated more evenly, increasing the efficiency of the dehydration process and improving product quality. In addition, because movement of the material holders reduces the sensitivity of the process to standingwave patterns, the holders do not need to be spaced as far apart as in systems with nonmovable holders, or systems with holders capable of fewer degrees of motion. For instance, in conventional fixed-frequency arrangements, the holders are typically positioned with greater separation between them to prevent the material from residing in hot or cold zones. According to embodiments described herein, however, the holders may be packed more densely, and therefore a larger number of holders and a correspondingly great quantity of material may be accommodated within the same chamber volume.

[0039] The material to be dehydrated may be any suitable organic or inorganic material from which moisture is to be removed, including, without limitation, food products (including pet food) and ingredients for supplements or pharmaceutical products.

[0040] Referring to FIG. 1, an example embodiment of a dehydrating system, or “dehydrator”, for dehydrating a material is shown and generally designated by reference numeral 100. Dehydrator 100 includes a dehydrating chamber 109 that defines an internal cavity in which multiple material holders 108 are positioned to receive and support the material to be dehydrated. According to some embodiments, material holders 108 may each comprise one or more trays, although other types of material holders may be used.

[0041] Microwave-generating devices are positioned on three sides of chamber 109 and are arranged to direct microwave radiation into chamber 109. According to some embodiments, the microwave-generating devices may be provided on only one side, on opposing sides, or on all four sides of chamber 109. Each microwave-generating device includes a magnetron 105 coupled through a waveguide 106 to a microwave aperture 116 which opens into chamber 109. The arrangement and orientation of the microwave-generating devices may be selected toprovide a desired distribution of microwave energy across material holders 108. According to some embodiments, magnetrons 105 operate at a substantially fixed frequency, for example about 2.45 GHz.

[0042] Material holders 108 are supported by a motion assembly 130 positioned beneath chamber 109 that enables both translational and rotational motion of material holders 108 within chamber 109. According to some embodiments, motion assembly 130 does not need to be positioned beneath chamber 109, and may be positioned in any other suitable location provided that motion assembly 130 is able to impart motion to material holders 108, as described in further detail below. Motion assembly 130 includes an x-axis motion stage 102, a y-axis motion stage 103, and a z-axis motion stage 101 for driving translational movement of material holders 108 along each of these three orthogonal axes. Motion assembly 130 further includes one or more rotational motion stages (including a z-axis rotational motion stage 104) for driving rotational motion about one or more the three orthogonal axes. The translational and rotational motion may be implemented using any of various means. For example, motion assembly 130 may employ linear actuators, servo or stepper motors, or rotary drives, which may be electrically, pneumatically, hydraulically, magnetically, or piezoelectrically powered. The specific type of actuator or drive assembly can be selected according to the desired range, precision, and speed of motion, as well as the operating environment within chamber 109. Motion may be transmitted to material holders 108 through shafts, linkages, or other coupling elements that pass through the chamber wall via a sealed feedthrough assembly 107, thereby maintaining vacuum integrity when dehydrator 100 operates under reduced pressure.

[0043] According to some embodiments, motion assembly 130 may be configured to enable translational movement of material holders 108 along each of only two orthogonal axes, while also enabling rotation of material holders 108 along one, two, or three of the orthogonal axes. The translational movement along multiple axes may be effected simultaneously or sequentially. For example, material holders 108 may be first translated along the x-axis and then along the y- axis, or alternatively may be translated in a direction having an x-axis component and a y-axis component. Similarly, rotational movement along multiple axes may be effected simultaneously or sequentially. For example, material holders 108 may be first rotated about the x-axis and then about the y-axis, or alternatively may be rotated about an oblique axis having an x-axis component and a y-axis component. Further still, the translational and rotational movementsmay be effected sequentially or simultaneously. For example, material holders 108 may be first translated and then rotated, or else may be translated at the same time as being rotated.

[0044] FIG. 2 shows dehydration chamber 109, material holders 108, magnetrons 105, and motion assembly 130 from a different perspective.

[0045] FIG. 3 shows motion assembly 130 in more detail, including x-axis motion stage 102, y- axis motion stage 103, and z-axis motion stage 101 for driving translational movement of material holders 108 along each of these three orthogonal axes. Also shown is z-axis rotational motion stage 104 for driving rotational motion about the z-axis. While dehydrator 100 is only configured for rotation of material holders 108 about the z-axis, according to other embodiments the dehydrator may be configured to enable rotation about additional axes, or about different axes. FIG. 3 also shows support sheets 121 that provide a stable platform for the motors and linear slides 123 that may allow smooth, low-friction motion of the stages.

[0046] Referring to FIG. 4, there is shown a control cabinet 118 which houses a control system 120 and associated power supplies 119. Control system 120, using one or more computer processors, computer-readable media, and / or circuitry, coordinates operation of motion assembly 130 and the operation of microwave-generating devices, by controlling power supplies 119. Control system 120 may include a programmable controller or equivalent circuitry configured to control motion parameters, such as speed, direction, and sequencing of translation and rotation, during dehydration. Control system 120 can also regulate magnetron power levels in real time to optimize energy distribution across the material.

[0047] Dehydrator 100 includes a number of sub-systems to assist with the dehydration process, although any of these subsystems may be omitted. These sub-systems may be controlled by control system 120 described above. As can be seen in FIG. 1 , a vacuum assembly 113 is connected to chamber 109 to reduce internal pressure when vacuum drying is desired. Dehydrator 100 also includes an infrared assembly 111 or other heat-generating device that supplies thermal energy to the chamber interior. Sensors for temperature, pressure, and humidity (not shown) may provide feedback signals to control system 120 for process monitoring and control. According to some embodiments, infrared assembly 111 comprises infraredemitting lamps positioned near the corners of chamber 109 and which radiate thermal energy directly toward the material or the interior surfaces of chamber 109 to assist in heating. According to some embodiments, infrared assembly 111 may be omitted or replaced by other heat-generating mechanisms.

[0048] In operation, a chamber door is opened and the material is loaded onto material holders 108 within chamber 109. The chamber door is then closed and dehydration is initiated, during which magnetrons 105 emit microwave radiation into chamber 109. At the same time, motion assembly 130 translates and rotates material holders 108 according to a programmed or machine-learned motion sequence. Simultaneous translation and rotation of material holders 108 has been found to enhance exposure of the material to microwave energy by continuously varying its spatial position and orientation relative to the electromagnetic field pattern within chamber 109. This dynamic movement disrupts the formation of localized hot and cold regions, ensuring that each portion of the material experiences a more consistent average field intensity over time. As a result, the dehydration process proceeds more uniformly and efficiently, reducing the risk of overheating or incomplete drying. According to some embodiments, it has been found that translating material holders 108 along the x and y-axes, and simultaneously rotating material holders 108 along the z-axis, is particularly effective at increasing dehydration uniformity. Generally, the specific pattern, amplitude, and rate of motion can be selected to suit the material type, load distribution, and desired drying uniformity, for example.

[0049] Referring to FIG. 5, a flow diagram illustrating an example method 500 of operating dehydrator 100 is shown.

[0050] At block 502, the material is placed onto material holders 108 positioned within dehydrating chamber 109. The chamber door is closed and sealed to prepare chamber 109 for operation.

[0051] At block 504, control system 120 activates vacuum assembly 113 to lower the pressure within chamber 109. Control system 120 may also activate other subsystems to establish the desired initial chamber pressure and / or temperature conditions. In addition, control system 120 initializes various operating parameters, such as microwave power level, motion sequence, and target dehydration profile.

[0052] At block 506, control system 120 initiates operation of motion assembly 130 to translate and / or rotate material holders 108 according to a pre-programmed or machine-learned motion pattern. The motion may include sequential or simultaneous translation along two or more axes, as well as simultaneous or sequential rotation about one or more axes, as described previously.

[0053] At block 508, control system 120 activates power supplies 119 for magnetrons 105 to begin the dehydration process.

[0054] At block 510, microwave energy is directed into chamber 109 while material holders 108 continue to move in accordance with the defined motion sequence. In addition, infrared assembly 111 and vacuum assembly 113, either individually or in combination, may be activated to assist with the dehydration. According to some embodiments, control system 120 may additionally activate a hot-air source (not shown) to increase the temperature within chamber 109. According to some embodiments, instead of or in addition to using forced hot-air convection, adhesive heating elements (such as pads) 117 may be provided on the outer walls of chamber 109 (see FIG. 2). Under reduced-pressure conditions, only limited gas and vapor movement may occurs within the chamber; however, heat can still be transferred to the material through thermal radiation and residual gas conduction to assist the dehydration process by supplementing the microwave heating.

[0055] At block 512, control system 120 maintains movement and energy control throughout the dehydration cycle. Process variables such as temperature, pressure, and / or moisture level within chamber 109 may be continuously monitored, and actuator parameters or power levels adjusted to maintain optimal drying conditions.

[0056] When the material has reached the desired degree of dehydration, the process advances to block 514, where control system 120 deactivates magnetrons 105 and motion assembly 130. If vacuum operation and / or thermal energy was used, chamber 109 may be returned to ambient pressure and / or temperature. The chamber door is then opened and the dehydrated material is removed from material holders 108, completing the process cycle.

[0057] In some embodiments, dehydrator 100 may be operated under reduced-pressure conditions suitable for sublimation or freeze-drying. For example, chamber 109 can be evacuated to a sufficiently low pressure that, when material pre-frozen prior to loading is subjected to microwave energy, moisture within the material transitions directly from the solid to the vapor phase. Under these conditions, the dehydrator may function as a hybrid vacuum- microwave-freeze-drying system in which moisture removal occurs through a combination of sublimation and vacuum evaporation, assisted by microwave heating. The relative contributions of sublimation, evaporation, and dehydration may be varied by adjusting the chamber pressure, temperature, and microwave power level. In some embodiments, dehydrator 100 may operate at chamber pressures between 0.05 kPa and 1.0 kPa (0.5-10 mbar) to enable sublimation and hybrid drying.

[0058] In some embodiments, control system 120 may be configured to execute a freeze- drying-assisted dehydration sequence. For example, the material may first be frozen externally and then loaded into chamber 109, after which microwave energy is applied under low-pressure conditions to accelerate sublimation. The microwave energy may selectively heat portions of the frozen material to enhance vapor release and thereby shorten the overall drying cycle compared with conventional freeze-drying methods.

[0059] Turning to FIG. 6, a schematic representation of a material holder 108 is shown together with three orthogonal axes, x, y, and z, illustrating the degrees of freedom within which the material holder 108 may be translated and rotated by motion assembly 130.

[0060] The word “a” or “an” when used in conjunction with the term “comprising” or “including” in the claims and / or the specification may mean “one”, but it is also consistent with the meaning of “one or more”, “at least one”, and “one or more than one” unless the content clearly dictates otherwise. Similarly, the word “another” may mean at least a second or more unless the content clearly dictates otherwise.

[0061] The terms “coupled”, “coupling” or “connected” as used herein can have several different meanings depending on the context in which these terms are used. For example, as used herein, the terms coupled, coupling, or connected can indicate that two elements or devices are directly connected to one another or connected to one another through one or more intermediate elements or devices via a mechanical element depending on the particular context. The term “and / or” herein when used in association with a list of products means any one or more of the products comprising that list.

[0062] As used herein, a reference to “about” or “approximately” a number or to being “substantially” equal to a number means being within + / - 10% of that number.

[0063] Use of language such as “at least one of X, Y, and Z,” “at least one of X, Y, or Z,” “at least one or more of X, Y, and Z,” “at least one or more of X, Y, and / or Z,” or “at least one of X, Y, and / or Z,” is intended to be inclusive of both a single product (e.g., just X, or just Y, or just Z) and multiple products (e.g., {X and Y}, {X and Z}, {Y and Z}, or {X, Y, and Z}). The phrase “at least one of” and similar phrases are not intended to convey a requirement that each possible product must be present, although each possible product may be present.

[0064] While the disclosure has been described in connection with specific implementations, it is to be understood that the disclosure is not limited to these implementations, and thatalterations, modifications, and variations of these implementations may be carried out by the skilled person without departing from the scope of the disclosure.

[0065] It is furthermore contemplated that any part of any aspect or implementation discussed in this specification can be implemented or combined with any part of any other aspect or implementation discussed in this specification.

Claims

Claims1 . An apparatus for dehydrating a material, comprising: a dehydrating chamber; one or more material holders positioned within the dehydrating chamber and configured to receive the material; one or more microwave-generating devices configured to direct microwave radiation into the dehydrating chamber to dehydrate the material received by one or more material holders; and a control system for controlling movement of the one or more material holders and configured, during dehydration of the material, to: translate the one or more material holders along each of at least two axes selected from among three orthogonal axes consisting of: an x-axis; a y-axis; and a z-axis; and rotate the one or more material holders about at least one of the three axes.

2. The apparatus of claim 1 , wherein the control system is configured, during dehydration of the material, to: translate the one or more material holders along each of the three axes.

3. The apparatus of claim 1 or 2, wherein the control system is configured, during dehydration of the material, to: translate the one or more material holders along each of the at least two axes simultaneously.

4. The apparatus of claim 3, wherein the control system is configured, during dehydration of the material, to simultaneously: translate the one or more material holders along each of the at least two axes simultaneously; and rotate the one or more material holders about at least one of the three axes.

5. The apparatus of claim 4, wherein the control system is configured, during dehydration of the material, to simultaneously: translate the one or more material holders along only each of the x-axis and the y-axis simultaneously; and rotate the one or more material holders about the z-axis only.

6. The apparatus of any one of claims 1-5, wherein the control system is configured, during dehydration of the material, to simultaneously: translate the one or more material holders along each of the three axes simultaneously; and rotate the one or more material holders along at least one of the three axes.

7. The apparatus of any one of claims 1-6, wherein the one or more microwave-generating devices are configured to generate frequency-invariant microwave radiation.

8. The apparatus of any one of claims 1-7, wherein at least one of the one or more microwavegenerating devices is a magnetron.

9. The apparatus of any one of claims 1-8, further comprising one or more heat-generating devices configured, during dehydration of the material, to heat an interior of the dehydrating chamber.

10. The apparatus of claim 9, wherein the one or more heat-generating devices comprise one or more adhesive heat-generating elements provided on one or more walls of the dehydrating chamber.

11. The apparatus of any one of claims 1-10, further comprising one or more vacuum-generating devices configured, during dehydration of the material, to reduce a pressure within the dehydrating chamber.

12. The apparatus of claim 11 , wherein the one or more vacuum-generating devices are configured, during dehydration of the material, to reduce the pressure within the dehydrating chamber to a level at which moisture within the material sublimes under freeze-drying conditions.

13. A method of dehydrating a material, comprising:directing microwave radiation at the material contained in a dehydrating chamber to dehydrate the material; and during the dehydration, moving the material within the dehydrating chamber such that the material is: translated along each of at least two axes selected from among three orthogonal axes consisting of: an x-axis; a y-axis; and a z-axis; and rotated about at least one of the three axes.

14. The method of claim 13, wherein translating the material comprises: translating the material along each of the three axes.

15. The method of claim 13 or 14, wherein translating the material comprises: translating the material along each of the at least two axes simultaneously.

16. The method of claim 15, wherein moving the material comprises simultaneously: translating the material along each of the at least two axes simultaneously; and rotating the material about at least one of the three axes.

17. The method of claim 16, wherein moving the material comprises simultaneously: translating the one or more material holders along only each of the x-axis and the y-axis simultaneously; and rotating the one or more material holders about the z-axis only.

18. The method of any one of claims 13-17, wherein moving the material comprises simultaneously: translating the material along each of the three axes simultaneously; and rotating the material about at least one of the three axes.

19. The method of any one of claims 13-18, wherein directing the microwave radiation comprises: directing the microwave radiation at the material without changing a frequency of the microwave radiation.

20. The method of any one of claims 13-19, further comprising: during the dehydration, heating an interior of the dehydrating chamber.

21. The method of claim 20, wherein heating the interior of the dehydrating chamber comprises using one or more adhesive heat-generating elements provided on one or more walls of the dehydrating chamber.

22. The method of any one of claims 13-21 , further comprising: during the dehydration, reducing a pressure within the dehydrating chamber.

23. The method of claim 22, wherein reducing the pressure comprises reducing the pressure within the dehydrating chamber to a level at which moisture within the material sublimes under freeze-drying conditions.

24. The method of any one of claims 13-23, wherein the material is a food product.

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