JP7417225B2 - Microwave processing device and microwave processing method - Google Patents

Description

The present invention relates to a microwave processing device and a microwave processing method.

A single-mode standing wave formed by irradiating microwaves into the resonator can efficiently heat the object to be processed within the resonator.
For example, Patent Document 1 describes a microwave heating device using a cavity resonator. In this technology, an axially symmetrical microwave electric field parallel to the central axis of a cylindrical cavity resonator is generated inside the cavity, and the object to be processed is placed in a circular tube placed in the area where the electric field intensity is concentrated. Heat to allow chemical reaction to proceed.
Furthermore, Patent Document 2 discloses that a flow pipe is arranged along a portion where the electric field strength of a single mode standing wave formed in a cavity resonator is maximum, and the fluid is caused to flow through the flow pipe. A flow-through type microwave-based chemical reaction device that heats quickly and uniformly is described.

The resonant frequency for forming a single-mode standing wave within the resonator also varies depending on changes in the state of the object to be processed placed within the resonator. Therefore, by measuring the resonant frequency inside the resonator while heating the object to be processed using a single mode standing wave, and controlling the frequency of the irradiated microwave according to the fluctuation of this resonant frequency, continuous , stable heat treatment becomes possible.

Japanese Patent Application Publication No. 2005-322582 Japanese Patent Application Publication No. 2010-207735

As mentioned above, the resonant frequency of the standing wave within the resonator also varies depending on the state change of the object to be processed placed within the resonator. On the other hand, from an industrial perspective, when incorporating a microwave generator that exceeds a specific frequency range called the ISM (Industrial, Scientific and Medical) band, permission in accordance with the Radio Law is required. . Therefore, it is desired that many microwave processing devices operate within the ISM band. That is, since the frequency range of the microwave generator is limited, it is necessary to control the resonant frequency within the resonator within this limited frequency range. However, controlling the frequency range of this resonant frequency requires changing the internal structure of the resonator, which poses practical problems such as the need for placement of the object to be processed and additional machining of the resonator (dimensional adjustment, etc.). It became.

In addition, for example, when the object to be treated is used as a catalyst, this catalyst is placed in a resonator, and a fluid is pumped into the resonator and heated by standing microwave waves to cause a chemical reaction, the catalyst itself has a product evaluation standard value. There are certain variations even within the resonator, and the responsiveness to microwaves when a catalyst is placed inside the resonator may differ. That is, the resonant frequency when using a certain catalyst that satisfies the product evaluation standard value may be different from the resonant frequency when using another catalyst that satisfies the product evaluation standard value. In that case, in order to adjust the resonant frequency of the resonator, it is inefficient to repack the catalyst into the resonator or perform additional work (dimensional adjustment) on the microwave irradiation space for each catalyst product. Therefore, productivity is poor.

The present invention provides a microwave processing device and a microwave processing method that make it possible to easily control the fluctuation of the resonant frequency of a single mode standing wave formed in a resonator to a frequency band of the ISM band. The task is to do so.

The above-mentioned problems of the present invention are solved by the following means.
[1]
A microwave processing device comprising a microwave generator, a resonator that forms a single-mode standing wave, and a tube at least partially disposed within the resonator,
The outer circumferential surface of the tube is constituted by a plane parallel to the resonator axis of the resonator, and the tube wall of the tube has a portion where the thickness differs in the resonator axis direction.
Microwave processing equipment.
[2]
The microwave processing device according to [1], wherein the inner wall surface of the tube has a taper and/or a step.
[3]
The tube according to [1] or [2], wherein the tube is disposed so as to be movable in the resonator axial direction along the resonator axis where the electric field strength or magnetic field strength within the resonator becomes maximum and uniform. Microwave processing equipment.
[4]
the tube has a multi-tube structure;
The microwave processing device according to any one of [1] to [3], wherein at least one layer of the tubes other than the outermost tube among the tubes is movable in the axial direction of the resonator.
[5]
a detection unit that detects a resonant frequency of a standing wave formed within the resonator;
a control unit that determines the insertion position of the tube along the resonator axis based on the resonance frequency detected by the detection unit;
The microwave processing device according to any one of [1] to [4], further comprising a drive unit that moves the tube along the resonator axis based on the insertion position of the tube determined by the control unit.
[6]
The tube is arranged so that the axial direction of the tube is aligned with the resonator axis direction where the electric field strength or magnetic field strength in the microwave irradiation space of the resonator is maximum and uniform, and a single mode is applied to the object to be processed placed inside the tube. A microwave processing method for irradiating a standing wave of
The tube has an outer circumferential surface parallel to the resonator axis, and the tube wall has a portion where the thickness differs in the resonator axis direction, and the tube is parallel to the resonator axis. A microwave processing method that adjusts the resonant frequency of the resonator by moving the resonator in the direction.

According to the microwave processing device of the present invention, it becomes possible to easily control the fluctuation of the resonant frequency of the single mode standing wave formed in the resonator to the frequency band of the ISM band. Furthermore, according to the microwave processing method, by moving the tube in the axial direction of the resonator, the fluctuation of the resonant frequency of the single mode standing wave formed in the resonator can be easily changed to the frequency band of the ISM band. It becomes possible to control.

1 is a cross-sectional view schematically showing a preferred embodiment of a microwave processing apparatus of the present invention. FIG. 2 is a sectional view showing a preferable example of a tube used in the microwave processing apparatus of the present invention. 2 is a sectional view showing a preferable example of a tube used in the microwave processing device of the present invention, (A) is a sectional view of the tube in a lowered state, and (B) is a sectional view of the tube in an ascended state. . FIG. 3 is a sectional view showing another preferred example of a tube used in the microwave processing device of the present invention. FIG. 3 is a cross-sectional view showing another preferable example of the tube used in the microwave processing apparatus of the present invention, in which (A) is a cross-sectional view of the tube in a lowered state, and (B) is a cross-sectional view of the tube in a higher state; It is. FIG. 7 is a sectional view showing yet another preferred example of a tube used in the microwave processing apparatus of the present invention. FIG. 3 is a cross-sectional view showing yet another preferable example of the tube used in the microwave processing device of the present invention, in which (A) is a cross-sectional view of the tube in a lowered state, and (B) is a cross-sectional view of the tube in a higher state; It is a diagram. It is a diagram showing the resonant frequency when the tube shown in FIG. 2 is moved up and down along the resonator axis of the cavity resonator of the microwave processing device, where the vertical axis shows the resonant frequency and the horizontal axis shows the resonant frequency of the tube. The insertion position is indicated. The insertion position 0 (reference position) was a position where the center position 2AC of the microwave irradiation space of the cavity resonator on the resonator axis coincided with the center position 61C of the pipe length of the central axis of the pipe. It is a diagram showing the resonant frequency when the tube shown in FIG. 3 is moved up and down along the resonator axis of the cavity resonator of the microwave processing device, where the vertical axis shows the resonant frequency and the horizontal axis shows the resonant frequency of the tube. The insertion position is indicated. The insertion position 0 (reference position) was a position where the center position 2AC of the microwave irradiation space of the cavity resonator on the resonator axis and the center position 62C in the cross-sectional direction of the stepped portion 62S of the stepped tube coincided.

Preferred embodiments of the invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments other than what is specified in the present invention. Furthermore, the form of the device shown in each drawing is a schematic diagram to facilitate understanding of the present invention, and the size and relative size of each component may be changed for convenience of explanation. However, it does not directly represent the actual relationship. Furthermore, matters other than those specified in the present invention are not limited to the external shapes and shapes shown in these drawings.

A microwave processing device according to the present invention includes a microwave generator, a resonator that forms a single-mode standing wave, and a tube that is at least partially disposed within the resonator. The outer peripheral surface of the tube is constituted by a plane parallel to the resonator axis of the resonator. The thickness of the tube wall of the tube has different portions in the axial direction of the resonator.
EMBODIMENT OF THE INVENTION Below, one preferable embodiment (1st Embodiment) of the microwave processing apparatus of this invention is described with reference to drawings.

[Microwave processing device]
As shown in FIG. 1, the microwave processing device 1 includes a resonator 2, a microwave supply means 3 for supplying microwaves at a frequency that can form a standing wave in the resonator 2, and 2 and a tube 6 at least partially disposed within the tube.
For example, a cavity resonator can be used as the resonator 2. Hereinafter, the resonator 2 will be explained as a cavity resonator 2. The microwave supply means 3 includes a microwave generator 4 that outputs microwaves, and an antenna 5 that supplies the output microwaves into the cavity resonator 2 from the microwave supply port 2S. Antenna 5 is connected to microwave generator 4 via cable 7 . The microwave generator 4 is equipped with a microwave oscillator that oscillates microwaves, and further includes a control unit 11 that controls the microwave oscillator, an attenuator that adjusts the attenuation level of the microwave, and an amplifier that amplifies the microwave power. , an isolator that absorbs reflected waves, a matching device that suppresses reflected waves, etc. (not shown) may be provided. The control unit 11 may be built into the microwave generator 4 or may be configured separately, for example.

The cavity resonator 2 forms a standing wave in the microwave irradiation space 2A inside thereof. The standing wave is a single mode of TM _mn0 mode (m, n are integers greater than or equal to 1) or TE _m0p mode (m, p are integers greater than or equal to 1).
For example, when performing microwave processing using an electric field, it is preferable to use TM _0n0 mode (n is an integer of 1 or more). In particular, in the TM ₀₁₀ mode standing wave in the cylindrical cavity resonator, the energy of the standing wave formed in the cavity resonator 2 is maximum at the resonator (center) axis C of the microwave irradiation space 2A. Since the electric field strength is maximum at the resonator axis C portion, it is easy to determine the position where the object to be processed is installed. Furthermore, the standing wave energy becomes uniform in the direction of the resonator axis C. The tube 6 is disposed so as to be movable along or near the resonator axis where this energy is maximum and uniform. An object to be processed 31 (indicated by an arrow in the drawing) is disposed within the tube 6 . Placing the object to be processed 31 means that the object to be processed 31 is present in the internal space 6SU of the tube 6, and the form in which the object to be processed 31 is left still in the tube 6 also applies. This term includes a form in which the object to be processed 31 is flowing in the pipe 6 and a form in which a portion thereof is flowing. The object to be processed 31 may or may not fill the entire inside of the tube 6 .

Further, when performing microwave processing using a magnetic field, it is preferable to use TM _mn0 mode (m and n are integers of 1 or more). Among them, the standing wave of TM ₁₁₀ mode in the cylindrical cavity resonator 2 and the TE ₁₀₂ mode in the rectangular cavity resonator have a magnetic field maximum at the resonator axis C, so it is difficult to install the object 31 to be processed. It is easy to determine the location.
It is preferable that the object to be processed be placed in a region where the magnetic field strength is strong, corresponding to the magnetic field strength inside the cavity resonator 2 . In particular, if it is placed in a region where the magnetic field strength formed within the cavity resonator 2 is maximum, more efficient heating becomes possible. For example, if the object to be processed 31 is a magnetic substance, more efficient heating can be achieved by absorbing magnetic field energy. If the object to be processed 31 is a metal, a substance containing ions, or the like and has electrical conductivity, heat can be generated using Joule heat due to a current induced in the substance by a magnetic field, and more efficient heating becomes possible.

Examples of the microwave oscillator include a microwave oscillator that can generate microwaves with an oscillation frequency of 2.45 GHz. From the viewpoint of being able to finely adjust the microwave frequency and miniaturizing the device, it is preferable to use a microwave generator using a semiconductor solid-state element. Examples of such a microwave oscillator include a microwave oscillator using a Gunn diode, an avalanche diode (input diode), and the like. Alternatively, in the MHz band, an oscillation circuit using an LC circuit including a coil and a capacitor can also be used. Further, examples include a VCO (Voltage Controlled Oscillator) and a PLL (Phase Locked Loop) circuit in which these elements and a frequency control mechanism are packaged. Microwaves generated by microwave oscillators are not limited to microwaves with a frequency of 2.45 GHz band, but also those that generate microwaves in other frequency bands such as 915 MHz band and 5.8 GHz band. It can be used as appropriate.

[tube]
The pipe 6 in which the object to be processed 31 to be subjected to microwave processing is disposed will be explained. The tube 6 has a shape in which the outer wall surface of the tube is a plane parallel to the resonator axis C, and has portions where the thickness of the tube wall differs in the resonator axis C direction. Hereinafter, preferred tube configurations will be described in detail.

<Tapered pipe>
As shown in FIG. 2, it is preferable that the tube 6 (61) has an outer wall surface 61WA formed of a surface parallel to the resonator axis C, and an inner wall surface 61WB formed into a continuously tapered shape. "Continuous" means that there is no step on the inner wall surface 61WB, and the inner wall surface 61WB tapers smoothly in the direction of the resonator axis C. Therefore, the internal space 61SU surrounded by the inner wall surface 61WB is a tapered space. The inner wall surface 61WB has a linearly tapered form and a curvedly tapered form. A shape that tapers linearly forms a so-called tapered shape. The taper rate of this tapered shape is preferably 1% or more, more preferably 5% or more, even more preferably 10% or more, and practically 30% or less, from the viewpoint of wide adjustment range of the resonance frequency. Further, from the viewpoint of fluidity of gas or liquid, it is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less.
The taper ratio can be determined by |(inlet inner diameter of tube 61)−(outlet inner diameter of tube 61)|/(pipe length of tube 61)×100%. In the tapered form, (inlet inner diameter of tube 61)>(outlet inner diameter of tube 61). Specifically, for example, the outer wall surface 61WA is preferably configured with a cylindrical outer peripheral surface, and the inner wall surface 61WB is preferably configured with an inverted truncated cone-shaped outer peripheral surface. Further, contrary to the tube 6 shown in FIG. 2, a tube having a tapered shape (inner diameter becomes thicker from the top to the bottom in the drawing) can also be used. In the case of a configuration in which the tip tapers linearly, the taper ratio can be determined using the above formula for determining the taper ratio even if (inlet inner diameter of the tube 61) < (outlet inner diameter of the tube 61).
In the present invention, a case in which the inner wall surface 61WB is tapered in a curved manner (not shown) is also included in the category of a tapered pipe. Hereinafter, a configuration in which the internal space 6SU tapers from the upper side to the lower side will be described.

By moving the tube 61 made of the tapered tube as described above along the direction of the resonator axis C, the volume occupied by the tube wall 61W of the tube 61 in the microwave irradiation space 2A changes. As a result, the relative dielectric constant in the microwave irradiation space 2A changes, so the resonant frequency of the cavity resonator 2 changes, making it possible to change the resonant frequency. At this time, in order to widen the range of variation, it is preferable to largely change the thickness of the tube wall 61W from a thin form to a thick form in the direction of the resonator axis C. In other words, it is preferable to largely change the inner diameter of the internal space 61SU of the tube 61 from a small diameter to a large diameter. However, the small diameter portion preferably has a diameter that allows the object to be processed 31 (see FIG. 1) to be easily introduced into the pipe, and also has a size that allows the object to be processed 31 to easily flow in and out of the internal space 61SU (for example, , diameter).
Furthermore, since the outer wall surface 61WA of the tube 61 is a surface configured parallel to the resonator axis C, the gap between the through holes 21 and 22 formed in the cavity resonator 2 and the outer wall of the tube 61 is There's no need to make it big. As a result, it is only necessary to provide the minimum necessary gap to allow movement of the tube 61 along the direction of the resonator axis C, thereby minimizing the leakage of microwaves from the through holes 21 and 22 into the microwave irradiation space 2A. can be limited.
Although not shown, the tube 61 has an outer wall surface parallel to the resonator axis C, and the inner wall surface has a tapered shape to increase the thickness of the tube wall 61W. It may also be a two-layered tube with an inner peripheral tube made of a tapered tube. In this case, it is preferable that the inner circumferential tube is joined to the outer circumferential tube and integrated. Further, it is preferable to use materials such as resin, glass tube, ceramic, etc., which have small dielectric loss, for the outer circumferential tube.
In the case of a tapered pipe, the internal space 61SU of the pipe 61 does not need to penetrate through the pipe 61 unless the pipe 61 is configured to allow the object to be processed 31 to flow therein; for example, one end of the pipe 61 can be a closed shape. For example, one end (for example, the lower end side) of the tube 61 may be closed.

In order to change the resonance frequency of the cavity resonator 2, the tube 61 may be moved up and down with respect to the cavity resonator 2.
For example, if the dielectric constant of the substance in the internal space 61SU is smaller than the dielectric constant of the material constituting the tube 61 and the resonant frequency is low, move the tube 61 in the direction of increasing the resonant frequency. Just let it happen. That is, as shown in FIG. 3(A), the tube 61 may be moved in a downward direction relative to the cavity resonator 2. The amount of movement (insertion position) can be determined from the relationship between the insertion position of the tube 61 in the direction of the resonator axis C and the resonance frequency, which has been measured in advance. In the present invention, the term "substance within the internal space" refers to an object disposed within the internal space, and includes, for example, air, an object to be treated, a catalyst, and the like. Moreover, "moving in the direction of lowering the tube" means that the tube moves from top to bottom in the drawing. The same applies hereafter.
In addition, if the dielectric constant of the substance in the internal space 61SU is smaller than the dielectric constant of the material constituting the tube 61, and if the resonant frequency is high, the tube 61 is moved in a direction to lower the resonant frequency. Just let it happen. That is, as shown in FIG. 3(B), the tube 61 may be moved in a direction that raises the tube 61 relative to the cavity resonator 2. The amount of movement (insertion position) in this case can also be determined from the relationship between the insertion position of the tube 61 in the direction of the resonator axis C and the resonance frequency, which has been measured in advance. In the present invention, "moving in the direction of raising the tube" means that the tube moves from the bottom to the top in the drawing. The same applies hereafter.
Note that if the dielectric constant of the substance in the internal space 61SU is larger than the dielectric constant of the material constituting the tube 6, the direction of the operation for moving the tube 61 described above may be reversed.

<Step pipe>
As shown in FIG. 4, the tube 6 (62) has an outer wall surface 62WA that is parallel to the resonator axis C, and an inner wall surface 62WB that has a stepped portion 62S so that the inside thereof is gradually tapered. It is preferable to do so. "Stepwise" means that there is a step on the inner wall surface 62WB of the tube, and the cross section of the internal space 62SU in the direction perpendicular to the resonator axis C changes stepwise in the resonator axis C direction. That is, the inner wall surface 62WB before and after the stepped portion may have a form in which the tube wall is smooth and the cross-sectional area of the inner space 62SU of the tube does not change, or may have a form in which it gradually changes. The stepped portion 62S is provided at at least one location on the inner wall surface 62WB, and may be provided at two or more locations.

By moving the tube 62 (also referred to as a stepped tube) having the stepped portion 62S as described above in the direction of the resonator axis C, the volume occupied by the tube wall 62W of the tube 62 existing in the microwave irradiation space 2A changes. Thus, the relative permittivity within the microwave irradiation space 2A can be changed. Thereby, the resonant frequency of the cavity resonator 2 changes, making it possible to change the resonant frequency. At this time, in order to widen the range of change, it is preferable to largely change the thickness of the tube wall from thin to thick in the resonator axial direction before and after the stepped portion 62S. "Before and after the stepped portion" means one end side and the other end side of the tube 62 with the stepped portion 62S as a boundary. In other words, this means that the inner diameter of the internal space SU of the tube 62 is significantly changed from a small diameter to a large diameter before and after the stepped portion 62S. However, it is preferable that the small diameter portion has a diameter that allows the object to be processed 31 (see FIG. 1) to easily flow inside the pipe. Further, the stepped portion 62S may have a tapered shape.
Furthermore, by configuring the outer wall surface 62WA of the tube 62 to be a plane parallel to the resonator axis C, the gap between the through holes 21 and 22 formed in the cavity resonator 2 and the outer wall surface 62WA of the tube 62 is increased. There's no need to take it. As a result, it is only necessary to provide the minimum necessary gap that allows the tube 62 to move in the direction of the resonator axis C, thereby minimizing the leakage of microwaves in the cavity resonator 2 from the through holes 21 and 22. can do.
Although not shown in the drawings, the tube 62 has an outer wall surface parallel to the resonator axis C, and an inner wall surface of the tube 62 to increase the thickness of the tube wall. It may also be a layered tube. In this case, the inner circumferential tube is preferably joined to the outer circumferential tube so as to be integrated. Further, it is preferable to use a material such as resin, glass, or ceramic with low dielectric loss for the inner peripheral tube.
In the case of a stepped tube, if the tube 62 is not configured to allow the object to be processed 31 to flow through the tube, the tube 62 may have, for example, a configuration in which one end is closed, as in the case of a tapered tube. For example, one end (for example, the lower end side) of the tube 62 may be closed.

In order to change the resonance frequency of the cavity resonator 2, the tube 62 may be moved up and down relative to the cavity resonator 2.
For example, if the dielectric constant of the substance in the internal space 62SU is smaller than the dielectric constant of the material constituting the tube 62 and the resonant frequency is low, move the tube 62 in the direction of increasing the resonant frequency. Just let it happen. That is, as shown in FIG. 5A, the tube 62 is lowered relative to the cavity resonator 2 so that the thinner portion 62Wt of the tube wall 62W enters the cavity resonator 2 more than the thicker portion 62WT. You can move it to The amount of movement (insertion position) can be determined from the relationship between the insertion position of the tube 62 in the direction of the resonator axis C and the resonant frequency, which has been measured in advance.
In addition, if the dielectric constant of the substance in the internal space 62SU is smaller than the dielectric constant of the material constituting the tube 62, and if the resonant frequency is high, the tube 62 is moved in a direction to lower the resonant frequency. Just let it happen. That is, as shown in FIG. 5(B) dd, the tube 62 is moved in the direction of raising the tube 62 relative to the cavity resonator 2 so that a large portion of the thick portion 62WT of the tube wall 62W enters the cavity resonator 2. Bye. The amount of movement (insertion position) in this case can also be determined from the relationship between the insertion position of the tube 62 in the direction of the resonator axis C and the resonance frequency, which has been measured in advance.

<Multiple tube>
The tube has a multi-tube structure of double tubes or more, and the outer wall surface of the outermost tube among the tubes is a plane parallel to the resonator axis, and at least one layer of other tubes other than the outermost tube is formed. The tube is movable along the resonator axis C direction. The multi-tube structure refers to a tube structure in which a plurality of layers of tubes that are movable in the tube center axis direction and have the same tube center axis are arranged, for example, concentrically. Hereinafter, a tube with a two-layer structure will be explained as a multi-tube structure.

As shown in FIG. 6, the tube 6 (63) has a two-layer structure, and an inner circumferential tube 63B is arranged along the inner wall surface of an outer circumferential tube 63A. The inner circumferential tube 63B is configured to be slidable or loosely inserted into the outer circumferential tube 63A, and is longer than the height of the microwave irradiation space 2A in the direction of the resonator axis C, and has a tube length shorter than the outer circumferential tube 63A. Preferably. Hereinafter, the term "loosely insertable" in the present invention includes a "slidable" state.
It is preferable that the outer circumferential tube 63A be fixed to the through hole 21 of the cavity resonator 2. By moving the inner tube 63B within the outer tube 63A in the direction of the resonator axis C, the volume of the tube wall 63W of the tube 63, which is the combination of the outer tube 63A and the inner tube 63B in the microwave irradiation space 2A, changes. As a result, the relative permittivity within the cavity resonator 2 can be changed. In order to increase the amount of change in dielectric constant due to the inner tube 63B, it is preferable to use a material with a low dielectric constant, such as resin, for the inner tube 63B. Due to the change in the dielectric constant described above, the resonant frequency of the microwave irradiation space 2A changes, making it possible to change the resonant frequency. At this time, in order to widen the range of change in the resonant frequency, it is preferable to set the inner circumferential tube 63B in a state in which it can move largely along the resonator axis C within the microwave irradiation space 2A. For example, the state of the tube 63 shown in FIGS. 7(A) and 7(B), which will be described later, is exemplified.
Further, since the outer wall surface 63WA of the tube 63 can be fixed to the through holes 21 and 22 formed in the cavity resonator 2, it is possible to prevent a gap from forming between the tube 63 and the cavity resonator 2. Therefore, leakage of microwaves in the microwave irradiation space 2A from the through holes 21 and 22 does not occur.
Note that in the case of multiple tubes, unless the tube 63 is configured to allow the object to be processed 31 to flow through the tube, the internal space 63SU of the tube 63 does not need to have a shape that penetrates the tube 63; for example, one end of the tube 63 can be a closed shape. For example, a configuration may be adopted in which one end (for example, the lower end side) of the outer circumferential tube 63A is closed, and the inner circumferential tube 63B can be loosely inserted from the open end (for example, the upper end side) of the outer circumferential tube 63A.

In order to change the resonant frequency of the cavity resonator 2 using the tube 63, the inner peripheral tube 63B of the tube 63 may be moved up and down with respect to the cavity resonator 2.
For example, if the relative permittivity of the substance in the internal space 63SU is smaller than the relative permittivity of the material constituting the tube 63, and the resonant frequency is low, the inner space of the outer tube 63A may be increased in the direction of increasing the resonant frequency. What is necessary is to move the inner circumferential tube 63B. That is, as shown in FIG. 7A, the inner circumferential tube 63B may be lowered relative to the cavity resonator 2 and moved in a direction out of the microwave irradiation space 2A. The amount of movement (insertion position) can be determined from the relationship between the insertion position of the inner circumferential tube 63B in the direction of the resonator axis C and the resonance frequency, which has been measured in advance.
Further, if the relative permittivity of the substance in the internal space 63SU is smaller than the relative permittivity of the material constituting the tube 63, and if the resonant frequency is high, the inside of the outer circumferential tube 63A is moved in the direction of lowering the resonant frequency. What is necessary is to move the inner circumferential tube 63B. That is, as shown in FIG. 7(B), the inner peripheral tube 63B may be raised relative to the cavity resonator 2 and moved in a direction out of the microwave irradiation space 2A. The amount of movement (insertion position) in this case can also be determined from the relationship between the insertion position of the inner circumferential tube 63B in the direction of the resonator axis C and the resonance frequency, which has been measured in advance.

In the above microwave processing apparatus 1 (see FIG. 1), a microwave generator 4 supplies microwaves to a cavity resonator 2 equipped with a tube 6 in which an object to be treated is arranged. The above standing wave is formed within the irradiation space 2A. For example, by providing the tube 6 along a portion where the electric field strength or magnetic field strength of this standing wave is maximum, the object to be treated 31 inside the tube 6 can be treated with high energy efficiency.

In the microwave processing device 1, the microwaves supplied from the microwave generator 4 are supplied with the frequency adjusted. By adjusting the supplied frequency, a standing wave can be stably formed within the cavity resonator 2. Furthermore, the intensity of the standing wave can be adjusted by outputting microwave power. In other words, it becomes possible to control the heating state of the object to be processed 31.

In the microwave processing apparatus 1 of the present invention, as described above with reference to FIGS. 3, 5, and 7, the tube 6 in which the object to be processed 31 is arranged is moved along the resonator axis C direction. Accordingly, the resonant frequency can be adjusted to be within a predetermined range (for example, within the ISM band). That is, by moving the tube 6 or a portion thereof along the resonator axis C, the relative permittivity within the microwave irradiation space 2A changes. This changes the resonant frequency and makes it possible to bring it into a predetermined resonant frequency range.
By raising the tube 6 or a portion thereof, the proportion of the tube wall 6W in the microwave irradiation space 2A increases. As a result, if the dielectric constant of the substance in the internal space 6SU is smaller than the dielectric constant of the material constituting the tube 6, the dielectric constant in the microwave irradiation space 2A increases, making it possible to lower the resonance frequency. can. Conversely, by lowering the tube 6 or a portion thereof, the proportion of the tube wall 6W in the microwave irradiation space 2A becomes smaller. As a result, the dielectric constant in the microwave irradiation space 2A becomes low, and the resonant frequency can be increased.
On the other hand, if the dielectric constant of the substance in the internal space 6SU is larger than the dielectric constant of the material constituting the tube 6, the height of the dielectric constant in the microwave irradiation space 2A is reversed. The resonant frequency can be adjusted by reversing the downward or upward direction of the section.

For example, when adjusting the position of the tube 61, first align the resonator axis C direction and the center axis of the tube 6 (61) with the resonator axis C direction. Then, the center position 2AC of the microwave irradiation space 2A on the resonator axis C is made to coincide with the center position 61C of the tube length on the central axis of the tube. This matched point is defined as a reference position for tube movement (a position where the amount of movement is 0). When adjusting the position of the tube 62, align the center axis of the tube 62 with the resonator axis C, and align the center position 62C of the stepped portion 62S in the cross-sectional direction with the center position 2AC of the microwave irradiation space 2A. , defines a reference position similar to the above. When adjusting the position of the tube 63, align the center axis of the tube 63 with the resonator axis C, and align the center position 63C of the length of the inner tube 63B with the center axis of the tube and the center position of the microwave irradiation space 2A. 2AC and define the same reference position as above.
In this way, the reference position from which the tube starts moving is defined.

Then, based on the resonance frequency of the cavity resonator 2 detected by the detection unit 12, the control unit 11 determines the insertion position (movement amount) of the tube 6 along the resonator axis C. Therefore, it is preferable that the cavity resonator 2 is provided with a detection unit 12 that detects the frequency of the standing wave in the microwave irradiation space 2A. The detection unit 12 may be any device that measures the energy intensity inside the microwave irradiation space 2A, processes the signal, and detects the frequency.
Further, it is preferable that the relationship between the resonance frequency and the insertion position of the tube with respect to the microwave irradiation space 2A is determined in advance, and the relationship is stored in the control unit 11. Then, based on the resonant frequency detected by the detector 12 and the above relationship determined in advance, the insertion position of the tube 6 is determined and instructed so that the resonant frequency falls within the ISM band. Although not shown, the instruction is preferably transmitted to a drive unit that moves the tube 6 up and down. In this way, the insertion position of the tube 6 is adjusted by the driver so that the resonant frequency of the resonator 2 falls within the ISM band.

Furthermore, before starting the processing of the object to be processed, the control unit 11 adjusts the frequency of the microwave generated from the microwave generator 4 or the amplifier (not shown) to the microwave irradiation space of the cavity resonator 2. It is also possible to match the frequency of the standing wave formed within 2A. It is preferable to match completely, but it also includes cases where the difference is within a certain range, for example, within 1%. Then, microwaves having the same frequency are irradiated into the microwave irradiation space 2A.

Specifically, the detection unit 12 detects an output signal proportional to the energy intensity of the microwave in the microwave irradiation space 2A. On the other hand, the microwave supplied to the microwave irradiation space 2A is a microwave generated from the microwave generator 4 or a microwave generated by amplifying the microwave generated from the microwave generator 4 with an amplifier. At this time, when the frequency generated from the microwave generator 4 is swept over the entire 2.45 GHz band or a part of the 2.45 GHz band, the output signal from the detection unit 12 obtains a distribution with a maximum value. This maximum value means that a standing wave is formed in the microwave irradiation space 2A, so by comparing it with the resonant frequency of the standing wave of the TM _0n0 mode in advance, the resonant frequency of the predetermined mode can be determined. can be detected.
Then, the control unit 11 matches the frequency of the microwave generated from the microwave generator 4 with the frequency of the detected microwave, and supplies microwaves with a frequency matched to the resonance frequency into the microwave irradiation space 2A. You can also.

As another means of matching the frequency of the microwave emitted from the microwave generator 4 with the resonant frequency within the microwave irradiation space 2A, the frequency of the microwave emitted from the microwave irradiation generator is fixed and the tube 6 The resonant frequency can also be changed by moving the position upward or downward. In this case, the resonant frequency can be adjusted by moving the tube 6 upward or downward to a position where the reflected wave from the microwave irradiation space reaches its minimum value or the output signal from the detection unit 12 reaches its maximum value. Can be adjusted.

It is desirable to perform the operation for detecting the resonance frequency periodically. When the disturbance is large, or when the temperature change, flow rate change, or composition change is large, it is desirable to perform the microwave treatment at a short cycle, for example, 1 second or less, immediately after starting the microwave treatment. On the other hand, when there are few disturbances, or when there are few temperature changes, flow rate changes, or composition changes, the microwave treatment may be performed at long intervals, for example, every minute, after a sufficient period of time has passed and the microwave treatment has stabilized.
When sweeping the frequency of the microwave from the microwave generator 4 in order to detect the resonance frequency, it is desirable that the width of the sweep frequency be narrow. However, if the fluctuation is large or the width of the sweep frequency is small, the maximum value may not be found within the sweep frequency. In that case, it is also desirable to widen the sweep frequency width and sweep again to detect the resonant frequency.

A preferred example of the configuration of the microwave processing device 1 of the present invention will be explained in detail.
<Cavity resonator>
There are no particular restrictions on the shape of the cavity resonator 2 used in the microwave processing device, as long as it has one microwave supply port 2S and a single mode standing wave is formed when microwaves are supplied. do not have. For example, a cylindrical or prismatic cavity resonator can be used. In this specification, a cylindrical cavity resonator includes a cavity resonator whose inner cross-sectional shape perpendicular to the central axis C is circular, as well as one whose cross-sectional shape is elliptical or oval. used for meaning. Further, a prismatic cylindrical cavity resonator means one in which the inner cross-sectional shape perpendicular to the central axis C is polygonal, and the cross-sectional shape is preferably tetragonal to decagonal. Further, the corners of the polygon may be rounded.
The size of the cavity resonator 2 can also be appropriately designed according to the purpose in the above-described embodiment. The cavity resonator 2 preferably has a low electrical resistivity and is usually made of metal, such as aluminum, copper, iron, magnesium, brass, stainless steel, or an alloy thereof. Alternatively, the surface of resin, ceramic, or metal may be coated with a substance having low electrical resistivity by plating, vapor deposition, or the like. Materials containing silver, copper, gold, tin, and rhodium can be used for the coating.

<Microwave supply>
The microwave processing device 1 of the present invention irradiates the cavity resonator 2 with microwaves from a microwave supply port 2S via an antenna 5 using microwaves generated from a microwave generator 4 or a microwave amplifier (not shown). It is supplied into the space 2A.

The microwave generator 4 can be, for example, a microwave generator whose oscillation frequency can be adjusted within a range of the ISM band, such as 2.45 GHz band, 5.8 GHz band, 915 MHz band, and the like. For example, a microwave generator using a semiconductor solid-state element or a microwave generator such as a magnetron can be used. From the viewpoint of being able to finely adjust the frequency of the microwave, it is preferable to use a microwave generator using a semiconductor solid-state element. Examples of microwave generators using semiconductor solid-state devices include microwave generators using Gunn diodes, avalanche diodes (impatted diodes), and the like. Note that the oscillation frequency is not limited to the above frequency band. Further, it is preferable to include an amplifier that amplifies the microwaves generated from the microwave generator 4. As this amplifier, a general microwave amplifier using a high frequency field effect transistor (FET) can be used.

In the embodiment shown in FIG. 1, a cylindrical cavity resonator is used as the cavity resonator 2. In the embodiment shown in FIG. A microwave supply port 2S is provided on or near a wall surface (inner surface of the cylinder) parallel to the central axis C of the cavity resonator 2. It is preferable that the microwave irradiation space 2A has an antenna 5 capable of applying high frequency waves through the microwave supply port 2S. As the antenna 5, it is preferable to use a magnetic field excitation antenna, such as a loop antenna, or an electric field excitation antenna, such as a monopole antenna. Antenna 5 is connected to microwave generator 4 via cable 7. For example, a coaxial cable can be used as the cable 7.
In this configuration, microwaves emitted from the microwave generator 4 are supplied from the antenna 5 into the microwave irradiation space 2A via the cable 7. A matching box (not shown) for suppressing reflected waves and an isolator (not shown) for protecting the microwave generator may be installed between the microwave generator 4 and the antenna 5. Alternatively, the function of a matching box may be achieved by adjusting the length of the cable.
It is preferable that the end surface of the antenna 5 is connected to a ground potential such as a wall surface of the cavity resonator. By applying a microwave (high frequency) to this antenna 5, a magnetic field is excited within the loop of the loop antenna, for example, and a standing wave can be formed within the cavity resonator.
For example, when a single mode standing wave of TM ₀₁₀ is formed in the above-mentioned cylindrical cavity resonator, the electric field intensity becomes maximum at the resonator axis C, and the electric field intensity becomes uniform in the direction of the resonator axis C. . Therefore, in the tube 6, it becomes possible to uniformly and efficiently microwave the object 31 to be treated that exists or flows inside the tube 6.
Note that microwaves may be supplied from the microwave generator 4 to the microwave supply port 3 using a waveguide.

<Heating the object to be processed>
In the microwave processing apparatus of the present invention, the object to be processed 31 (for example, the object to be heated disposed in the tube 6) is exposed to the energy (electric field or magnetic field) intensity of the standing wave inside the cavity resonator 2. They are arranged correspondingly. In particular, more efficient heating can be achieved by arranging them along the portion where the electric field or magnetic field strength of the standing wave formed within the cavity resonator 2 is maximum.

In the microwave processing apparatus 1 shown in FIG. 1, the object to be processed 31 placed in the tube 6 is not particularly limited, and examples include liquid, solid, powder, and mixtures thereof. Alternatively, a honeycomb structure, a catalyst, etc. (not shown) installed in the pipe 6 in advance can be used.
When the object to be treated 31 is passed through the pipe 6, the temperature of the object to be treated is continuously controlled by conveying the object to be treated 31 using a feeding means (for example, a pump) 41 or the like. I can do it. Since the progress of many chemical reactions can be controlled by temperature, the microwave processing apparatus 1 of the present invention can be suitably used for controlling chemical reactions.
When the object to be treated is a honeycomb structure, the microwave processing device can be used, for example, to control the temperature of a gaseous substance passing through the honeycomb structure. Further, when the object to be treated is a catalyst, it can be used to cause a chemical reaction by the action of the catalyst. It is also preferable that the catalyst be supported on a honeycomb structure.

[Microwave processing method]
The microwave processing method involves irradiating microwaves into a cavity resonator to generate TM _mn0 mode (m, n are integers of 1 or more) or TE _m0p mode (m, p are integers of 1 or more). A single-mode standing wave (an integer of ) is formed, and the object to be processed is processed using the standing wave. As the microwave, for example, a microwave having a frequency of 2.45 GHz band is used. Further, the object to be processed is arranged along the part where the energy (electric field or magnetic field) strength of the standing wave is maximum.
In this microwave processing method, it is preferable to use the tapered tube shown in FIG. 2, for example, in the microwave processing apparatus 1 described above. Hereinafter, a case will be described in which a tapered tube is used in the microwave processing apparatus 1, but the present invention can be similarly applied to a case in which a stepped tube or a multiple tube is used.
Specifically, the object to be processed 31 can be heated using the microwave processing apparatus 1 described above. First, microwaves supplied from the microwave generator 4 with the frequency adjusted as described above are supplied into the microwave irradiation space 2A of the cavity resonator 2. By adjusting the frequency, the electric field or magnetic field intensity distribution of the standing wave formed within the cavity resonator 2 can be controlled to a desired distribution state, and the intensity of the standing wave can be adjusted by the output of the microwave. be able to. That is, it becomes possible to control, for example, the heating state (temperature) of the object to be processed 31 inside the tube 6 (inner space 6SU).
The frequency of the microwave is, for example, in the 2.45 GHz band, and is capable of forming a specific single mode standing wave in the microwave irradiation space 2A.

After performing the above initial settings, microwave processing is performed. As processing progresses, a shift occurs in the resonance frequency. In that case, the tube 6 (61) is moved in the direction of the resonator axis C according to the amount of shift in the resonance frequency to return the resonance frequency to the set value. For example, if the relative permittivity of the substance in the internal space 61SU is smaller than the relative permittivity of the material constituting the tube 61, and if the resonant frequency is smaller than the set value, the In this manner, the tube 61 is lowered and moved in a direction in which the volume of the tube 61 in the microwave irradiation space 2A decreases (in a direction in which the dielectric constant decreases), thereby increasing the resonance frequency. Conversely, for example, if the relative dielectric constant of the substance in the internal space 61SU is smaller than the relative permittivity of the material constituting the tube 61, and the resonance frequency is larger than the set value, as shown in FIG. As shown in , the tube 61 is raised and moved in a direction in which the volume of the tube 61 in the microwave irradiation space 2A increases (in a direction in which the dielectric constant increases), thereby lowering the resonance frequency.
The resonant frequencies of the tubes 6 (62) and 6 (63) shown in FIGS. 4 and 6 can also be controlled by raising and lowering them in the same way as the tube 6 (61) shown in FIG. That is, by moving the tube 6 in the direction in which the volume of the tube 6 in the microwave irradiation space 2A becomes smaller, the resonance frequency can be increased, and in the direction in which the volume of the tube 6 in the microwave irradiation space 2A becomes larger. By moving the tube 6, the resonance frequency can be lowered.

EXAMPLES The present invention will be described in more detail below based on Examples, but the present invention is not to be construed as being limited to these.

[Example 1]
The microwave processing apparatus 1 shown in FIG. 1 was used. A cavity resonator 2 having a cylindrical microwave irradiation space 2A was used as a single mode resonator that forms a TM ₀₁₀ mode standing wave. The microwave irradiation space 2A had a cylindrical shape with an inner diameter of 69.5 mm. On the upper and lower surfaces of the cavity resonator 2, through holes 21 and 22 were formed along the resonator axis (center axis) C through which a tube 6 (61) having an outer diameter of 15 mm was passed. A tube 61 made of quartz (relative dielectric constant 4.0) with an outer diameter of 15 mm, a length of 50 mm, an inlet inner diameter of 2 mm, and an outlet inner diameter of 14 mm, as shown in FIG. 2, is arranged so as to be loosely inserted therein. The central axis of the tube 61 coincided with the resonator axis C. Note that the substance in the internal space 61SU was air (relative permittivity: 1.0).
The reference position 0 was defined as the position where the center position 61C of the length of the tube 61 in the direction of the central axis of the tube and the center position 2AC of the microwave irradiation space 2A in the direction of the resonator axis C coincided. Then, the resonance occurs when the insertion position of the tube 61 is changed every 2 mm along the resonator axis C from the position where the tube 61 is raised by 10 mm (10 mm) to the position where it is lowered by 10 mm (-10 mm) with respect to the reference position 0. The frequency was measured. The results are shown in FIG. As shown in FIG. 8, it was found that the resonance frequency could be varied by changing the insertion position. Since the ISM band of the microwave frequency band that can be used in the industrial field is 2.4 to 2.5 GHz, it can be used industrially by changing the insertion position of the tapered reaction tube from -8 mm to +6 mm. It was found that it can be adjusted within the frequency range (2.4 GHz to 2.5 GHz). When manufacturing microwave irradiation spaces and tubes, the actual resonant frequency varies depending on the processing accuracy, but it was found that it is possible to finely adjust the deviation in the resonant frequency due to changes in processing accuracy and the object to be processed.

[Example 2]
The microwave processing apparatus 1 shown in FIG. 1 was used. The cavity resonator 2, which is a single mode resonator that forms a TM ₀₁₀ mode standing wave and has a cylindrical cavity microwave irradiation space 2A, was used as the resonator. The microwave irradiation space 2A had a cylindrical shape with an inner diameter of 71 mm. Through holes 21 and 22 were formed in the upper and lower surfaces of the cavity resonator 2 so that a tube 6 (62) having an outer diameter of 15 mm could pass through the cavity along the resonator axis (center axis) C. These through-holes 21 and 22 are fitted with quartz tubes (relative dielectric A tube 62 having a diameter of 4.0) is arranged so as to be loosely insertable. Therefore, the central axis of the tube 62 coincided with the resonator axis C. Note that the substance in the internal space 61SU was air (relative permittivity: 1.0). The reference position 0 was defined as the position where the center position in the cross-sectional direction of the step portion 62S of this step tube and the center position 2AC of the microwave irradiation space 2A coincided. Then, resonance occurs when the insertion position of the tube 62 is changed every 2 mm from a position (10 mm) raised by 10 mm to a position (-10 mm) lowered by 10 mm with respect to the reference position 0 along the resonator axis C. The frequency was measured. The results are shown in FIG. As shown in FIG. 9, it was found that the resonance frequency could be varied by changing the insertion position. It has been found that by varying the insertion position of this stepped tube 62 from -4 mm to +2 mm, it is possible to adjust the frequency within an industrially usable frequency range (2.4 GHz to 2.5 GHz). When manufacturing microwave irradiation spaces and tubes, the actual resonant frequency varies depending on the processing accuracy, but it was found that it is possible to finely adjust the deviation in the resonant frequency due to changes in processing accuracy and the object to be processed.

1 Microwave processing device 2 Resonator 2A Microwave irradiation space 2AC Center position of microwave irradiation space 2S Microwave supply port 3 Microwave supply means 4 Microwave generator 5 Antenna 6, 61, 62, 63 Tube 6SU, 61SU, 62SU, 63SU Internal space 6W, 61W, 62W, 63W Pipe wall 7 Cable 11 Control part 12 Detection part 21, 22 Through hole 31 Object to be treated 61C Center position of pipe length in the central axis direction of pipe 61WA, 62WA, 63WA Outer wall surface 61WB, 62WB, 63WB Inner wall surface 62C Center position in the cross-sectional direction of the stepped portion 62S Stepped portion 62Wt Thin portion of the tube wall 62WT Thick portion of the tube wall 63A Outer tube 63B Inner tube 63C Pipe length of the inner tube in the direction of the center axis of the tube Center position of C resonator axis (center axis)

Claims (4)

A microwave processing device comprising a microwave generator, a resonator that forms a single mode standing wave, and a tube in which at least a portion of the tube is movable in the axial direction of the resonator. ,
The outer wall surface of the tube disposed within the resonator is configured with a plane parallel to the resonator axis of the resonator, and the inner wall surface of the tube disposed within the resonator has a continuously tapered shape. accomplish,
Microwave processing equipment. The microwave processing device according to claim 1 , wherein the tube is disposed so as to be movable in the resonator axis direction along the resonator axis where the electric field strength or magnetic field strength within the resonator becomes maximum and uniform. . a detection unit that detects a resonant frequency of a standing wave formed within the resonator;
a control unit that adjusts the insertion position of the tube along the resonator axis based on the resonance frequency detected by the detection unit;
The microwave processing device according to claim 1 or 2 , further comprising a drive section that moves the tube along the resonator axis based on the insertion position of the tube determined by the control section. The tube is arranged so that the axial direction of the tube is aligned with the resonator axis direction where the electric field strength or magnetic field strength in the microwave irradiation space of the resonator is maximum and uniform, and a single mode is applied to the object to be processed placed inside the tube. A microwave processing method for irradiating a standing wave of
The tube placed in the resonator has an outer wall surface parallel to the resonator axis, and an inner wall surface of the tube placed in the resonator has a continuously tapered shape. and adjusting the resonant frequency of the resonator by moving the tube in the axial direction of the resonator.

Images