Microwave heating apparatus and method for acquiring temperature distribution

Abstract

The present invention provides a microwave heating apparatus capable of obtaining the temperature distribution inside a container that is subjected to microwave heating. [Solution] The microwave heating device 1 comprises a container 11 for heating an object to be heated by irradiation with microwaves, two or more sound wave transmitters 13 positioned on the outer surface of the container 11 along at least a portion of the periphery of a temperature measurement area where at least a portion of the object to be heated is placed, and emitting sound waves toward the inside of the container 11, and two or more sound wave receivers 14 positioned on the outer surface of the container 11 along at least a portion of the periphery of the temperature measurement area, and receiving sound waves emitted by the two or more sound wave transmitters 13, and the temperature distribution inside the object to be heated is obtained using the propagation time of the sound waves emitted by the two or more sound wave transmitters 13 and received by the two or more sound wave receivers 14.

Description

[[Technical Field]]

[0001] The present invention relates to a microwave heating device and the like for heating an object to be heated by irradiating the object with microwaves. [[Background Art]]

[0002] When heating an object to be heated by microwave irradiation, the temperature is measured, and the measured temperature is used to control the output of microwaves. [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0003] Heating using microwaves is internal heating, and the temperature of the object to be heated can vary greatly depending on the position. In conventional microwave heating devices, only the surface temperature of the object to be heated or the temperature at a specific position in the object to be heated can be measured.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a microwave heating device or the like that can acquire the temperature distribution inside an object to be heated in microwave heating. [[Means for Solving the Problem]]

[0005] In order to solve such problems, a first aspect of the present invention provides: a container for heating an object placed therein by irradiation with microwaves; two or more sound wave transmitters disposed on an outer surface of the container along at least part of a periphery of a temperature measurement region where at least a part of the object to be heated is placed, and configured to transmit sound waves toward the inside of the container; and two or more sound wave receivers disposed on the outer surface of the container along at least part of the periphery of the temperature measurement region, and configured to receive sound waves transmitted by the two or more sound wave transmitters. This is a microwave heating device.

[0006] Furthermore, a second aspect of the present invention is a microwave heating apparatus according to the first aspect, wherein the two or more sound wave transmitters and the two or more sound wave receivers are arranged in an annular manner on the outer surface of the container.

[0007] Furthermore, a third aspect of the present invention is a microwave heating apparatus according to the first aspect, further comprising an acquisition unit that acquires the temperature distribution inside the object to be heated using the propagation time of each sound wave emitted by the two or more sound wave transmitters and received by the two or more sound wave receivers.

[0008] Furthermore, a fourth aspect of the present invention is a microwave heating apparatus according to the third aspect, wherein the acquisition is performed using the relationship between propagation speed and temperature obtained by measuring the propagation speed of sound waves while the object to be heated is heated to multiple temperatures.

[0009] Furthermore, a fifth aspect of the present invention is a microwave heating apparatus according to the third or fourth aspect, wherein the acquisition is performed using the CT method.

[0010] Furthermore, a sixth aspect of the present invention is a microwave heating apparatus according to the fourth or fifth aspect, wherein the object to be heated includes a solid.

[0011] Furthermore, a seventh aspect of the present invention is a microwave heating apparatus according to the fourth or fifth aspect, wherein the object to be heated includes a liquid.

[0012] Furthermore, an eighth aspect of the present invention is a microwave heating apparatus according to any of the first to seventh aspects, further comprising a moving mechanism for moving the two or more sound wave transmitters and the two or more sound wave receivers in a first direction which is perpendicular to the plane direction of the temperature measurement area.

[0013] Furthermore, a ninth aspect of the present invention is a microwave heating apparatus according to any third to seventh aspect, further comprising a moving mechanism for moving the two or more sound wave transmitters and the two or more sound wave receivers in a first direction which is perpendicular to the plane direction of the temperature measurement area, wherein the acquisition unit acquires the temperature distribution of the temperature measurement area at a plurality of positions in the first direction.

[0014] Furthermore, a tenth aspect of the present invention is a method for obtaining a temperature distribution, comprising the steps of: transmitting sound waves toward the inside of a container using two or more sound wave transmitters that emit sound waves, which are arranged on the outer surface of a container along at least a portion of the periphery of a temperature measurement area in which at least a portion of the object to be heated is placed within the container by microwave irradiation; receiving the sound waves transmitted by the two or more sound wave transmitters using two or more sound wave receivers that receive sound waves, which are arranged on the outer surface of the container along at least a portion of the periphery of the temperature measurement area; and obtaining the temperature distribution inside the object to be heated using the propagation time of the sound waves transmitted by the two or more sound wave transmitters and received by the two or more sound wave receivers. [Effects of the Invention]

[0015] According to one aspect of the present invention, the temperature distribution inside an object being heated by microwave heating can be obtained using sound waves. [Brief explanation of the drawing]

[0016] [Figure 1] A schematic diagram showing the external appearance of the container of a microwave heating apparatus according to an embodiment of the present invention. [Figure 2] Longitudinal cross-sectional view of the container of the microwave heating apparatus according to the same embodiment. [Figure 3] Cross-sectional view of the container of the microwave heating apparatus according to the same embodiment. [Figure 4] Functional block diagram showing the configuration of the microwave heating device according to the same embodiment. [Figure 5A] This figure shows an example of the mounting configuration of the sound wave transmitter in the same embodiment. [Figure 5B] This figure shows an example of the mounting configuration of the sound wave receiver in the same embodiment. [Figure 5C] This figure shows another example of the mounting configuration of the sound wave transmitter in the same embodiment. [Figure 5D] This figure shows another example of the mounting configuration of the sound wave receiver in the same embodiment. [Figure 6] Diagram showing another example of the sound wave transmitter and sound wave receiver attached to the outer surface of the container in the same embodiment [Figure 7] Schematic diagram for explaining the moving mechanism according to the same embodiment [Figure 8] Cross-sectional view for explaining the moving mechanism according to the same embodiment [Figure 9] Transverse cross-sectional view showing another example of the arrangement of the sound wave transmitter and the sound wave receiver in the same embodiment [Figure 10] Transverse cross-sectional view showing another example of the arrangement of the sound wave transmitter and the sound wave receiver in the same embodiment DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of a microwave heating device and a temperature distribution acquisition method according to the present invention will be described. In the following embodiments, components denoted by the same reference numerals are the same or equivalent, and repeated description thereof may be omitted. The microwave heating device according to the present embodiment acquires the temperature distribution of a temperature measurement region using the propagation time of sound waves received by two or more sound wave receivers that are disposed on at least a part of the periphery of the temperature measurement region, the sound waves being transmitted by two or more sound wave transmitters disposed on at least a part of the periphery of the temperature measurement region where at least a part of an object to be heated inside a container subjected to microwave heating is disposed.

[0018] FIG. 1 is a schematic diagram showing the external appearance of the container 11 of the microwave heating device 1 according to the present embodiment, FIG. 2 is a vertical cross-sectional view showing the internal structure of the container 11 of the microwave heating device 1, FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1, and FIG. 4 is a functional block diagram showing the configuration related to the acquisition and control of the temperature distribution of the microwave heating device 1. Note that, in FIG. 3, the internal structures of the sound wave transmitter 13 and the sound wave receiver 14 are omitted.

[0019] As shown in Figures 1 to 4, the microwave heating device 1 according to this embodiment comprises a container 11 for heating an object to be heated by irradiation with microwaves, a microwave absorber 12 disposed inside the container 11, two or more sound wave transmitters 13 that emit sound waves toward the inside of the container 11, and two or more sound wave receivers 14 that receive sound waves emitted by the two or more sound wave transmitters 13. The microwave heating device 1 may further comprise an acquisition unit 15 that acquires the temperature distribution inside the container 11 using the propagation time of each sound wave emitted by the two or more sound wave transmitters 13 and received by the two or more sound wave receivers 14. The microwave heating device 1 may further comprise, if necessary, a storage unit 16 that stores a reference value for temperature, an abnormality detection unit 17 that detects abnormalities using the acquired temperature distribution and the reference value, a microwave generator 18 that generates microwaves, a waveguide 19 that guides the microwaves generated by the microwave generator 18 into the container 11, and a control unit 20 that controls the output of microwaves using the acquired temperature distribution and the abnormality detection result.

[0020] The microwave heating apparatus 1 according to this embodiment can be any type of apparatus that heats an object to be heated by irradiating it with microwaves inside a container 11. The object to be heated may be a solid, liquid, or gas, among other things. The purpose of performing microwave heating inside the container 11 is not specified. By irradiating the object to be heated with microwaves inside the container 11, processes such as heating, chemical reactions, drying, decomposition, detoxification, and sterilization may be carried out. If the object to be heated is a solid, for example, calcination of ore may be carried out inside the container 11. Another example is that chemical recycling may be carried out inside the container 11. This embodiment mainly describes the case in which a predetermined gas is heated inside the container 11. The gas to be heated may be a raw material mainly composed of saturated hydrocarbons such as naphtha. In this case, the saturated hydrocarbons may be decomposed inside the container 11 to produce decomposition products. The decomposition products may contain at least one of the following: hydrogen, methane, ethylene, ethane, propylene, propane, and butylene, and may also contain other hydrocarbons.

[0021] The container 11 may be, for example, a container for continuous microwave heating of the object to be heated, or a container for batch microwave heating of the object to be heated. In this embodiment, the former case will be mainly described. As an example, the container 11 may have a supply port 11a for supplying raw materials and an outlet 11b for discharging the heated substance inside the container 11. The size of the supply port 11a and the outlet 11b may be determined, for example, so that microwaves do not leak from inside the container 11.

[0022] The container 11 preferably has walls that do not allow microwaves to pass through in order to prevent microwaves from leaking out of the internal space. Therefore, the walls of the container 11 may be made of a microwave-reflective material. The microwave-reflective material may be, for example, a metal. The metal is not particularly limited, but may be, for example, stainless steel, carbon steel, nickel, nickel alloy, copper, copper alloy, etc.

[0023] A microwave absorber 12 may be present inside the container 11. This microwave absorber 12 may be heated to a predetermined temperature by microwaves, and the raw material may be heated as it passes through the microwave absorber 12. For example, the raw material supplied from the supply port 11a may be heated in the microwave absorber 12, and the heated material may be discharged from the discharge port 11b. The microwave absorber 12 may, for example, be present so as to completely cover the cross section perpendicular to the flow path in the internal space of the container 11. The microwave absorber 12 may also have gaps through which the raw material can pass, for example, in a honeycomb structure.

[0024] The microwave absorber 12 may have microwave absorbing properties at the microwave frequency and temperature during operation of the microwave heating device 1. A substance whose temperature rises significantly when irradiated with microwaves at the microwave frequency and temperature during operation of the microwave heating device 1 can be considered to have microwave absorbing properties. The material of the microwave absorber 12 is not particularly limited, but may be one or more of the following: silicon carbide, magnetite, carbons other than fullerenes (e.g., graphite, carbon nanotubes, and activated carbon), iron, nickel, cobalt, copper, ferrite, Si3N4, CoO, Co3O4, CuO, SiC, FeO, Fe3O4, WC, MnO2, and TiO2.

[0025] The two or more sound wave transmitters 13 emit sound waves and may be, for example, speakers. The sound wave transmitters 13 may emit, for example, pulsed sound waves. The two or more sound wave transmitters 13 are arranged on the outer surface of the container 11 along at least a portion of the periphery of the temperature measurement area in at least a portion of the object to be heated inside the container 11. The temperature measurement area may include, for example, a cross-sectional area relating to at least a portion of the object to be heated inside the container 11. This embodiment mainly describes the case where the sound wave transmitters 13 are arranged along the entire circumference of the temperature measurement area. The temperature measurement area may be, for example, a planar area inside the container 11. As an example, the temperature measurement area may be a portion of the microwave absorber 12. This embodiment mainly describes the case where the temperature measurement area is a cross-sectional area of ​​the microwave absorber 12. The frequency of the sound waves emitted by the sound wave transmitters 13 is not particularly limited, but may be, for example, in the range of 1 Hz to 50 kHz. The frequency of the sound waves emitted by the sound wave transmitters 13 may be, for example, fixed or variable.

[0026] The two or more sound wave receivers 14 are for receiving sound waves and may be, for example, microphones. The two or more sound wave receivers 14 are arranged on the outer surface of the container 11 along at least a portion of the perimeter of the temperature measurement area inside the container 11. This embodiment mainly describes the case in which the sound wave receivers 14 are arranged along the entire circumference of the temperature measurement area.

[0027] It is preferable that the two or more sound wave transmitters 13 and two or more sound wave receivers 14 are arranged such that sound waves emitted from each sound wave transmitter 13 and passing through the temperature measurement area are received by at least some of the sound wave receivers 14. It is also preferable that the two or more sound wave transmitters 13 and two or more sound wave receivers 14 are arranged such that a wider range of the temperature measurement area is covered by the propagation path of the sound waves emitted from the sound wave transmitters 13 and received by the sound wave receivers 14. Furthermore, when the temperature of each sub-region included in the temperature measurement area is acquired, it is preferable that sound waves propagating between two or more pairs of sound wave transmitters 13 and sound wave receivers 14 pass through each sub-region. In this embodiment, as an example, the case in which the two or more sound wave transmitters 13 and two or more sound wave receivers 14 are arranged in a ring on the outer surface of the container 11 so as to surround the temperature measurement area, which is a planar region, will be mainly described. As shown in Figures 1 and 3, two or more sound wave transmitters 13 and two or more sound wave receivers 14 may be arranged alternately, for example, along the outer surface 11c of the container 11.

[0028] Here, the mounting of the sound wave transmitter 13 and sound wave receiver 14 to the outer surface 11c of the container 11 will be described. Figures 5A and 5B show an example of a sound wave transmitter 13 and sound wave receiver 14 mounted to the outer surface 11c of the container 11. As shown in Figures 5A and 5B, the sound wave transmitter 13 and sound wave receiver 14 may be mounted so that the sound wave transmitting surface of the sound wave transmitter 13 and the sound wave receiving surface of the sound wave receiver 14 are in contact with the outer surface 11c of the container 11. In this embodiment, the case in which the sound wave transmitter 13 and sound wave receiver 14 are mounted to the outer surface 11c of the container 11, as shown in Figures 5A and 5B, will be mainly described.

[0029] Figures 5C and 5D show another example of a sound wave transmitter 13 and a sound wave receiver 14 attached to the outer surface 11c of a container 11. As shown in Figures 5C and 5D, the sound wave transmitter 13 and the sound wave receiver 14 may be attached to the outer surface 11c of the container 11 via a mounting member 21. The mounting member 21 may, for example, have a plate-shaped member 21a attached so that the sound wave transmitting surface of the sound wave transmitter 13 and the sound wave receiving surface of the sound wave receiver 14 are in contact with each other, and a rod-shaped member 21b with one end connected to the plate-shaped member 21a. The rod-shaped member 21b may be provided so as to penetrate the wall of the container 11, with one end protruding toward the outer surface 11c of the container 11 and the other end protruding toward the inner surface 11d of the container 11. The material of the plate-shaped member 21a and the rod-shaped member 21b may be a material that easily transmits sound waves, such as metal. In this way, when the sound wave transmitter 13 and the sound wave receiver 14 are attached to the outer surface 11c of the container 11 via the mounting member 21, sound waves from the sound wave transmitter 13 can be transmitted more reliably to the inside of the container 11 via the rod-shaped member 21b, and sound waves propagating inside the container 11 can be reliably transmitted via the rod-shaped member 21b to the sound wave receiver 14 located outside the container 11.

[0030] It goes without saying that the method of attaching the sound wave transmitter 13 and sound wave receiver 14 to the outer surface 11c of the container 11 may be other than that described above.

[0031] The acquisition unit 15 acquires the temperature distribution inside the heated object using the propagation time of each sound wave transmitted by two or more sound wave transmitters 13 and received by two or more sound wave receivers 14. It is known that the propagation speed of sound waves changes depending on the temperature of the region through which the sound waves propagate. The propagation speed of sound waves increases as the temperature of the region through which the sound waves propagate increases. In addition, the propagation distance of sound waves from the sound wave transmitters 13 to the sound wave receivers 14 is known. Therefore, the acquisition unit 15 can acquire the temperature distribution of the temperature measurement region from the measured sound wave propagation time by using the CT (Computed Tomography) method. The temperature distribution may be, for example, the temperature of a set of sub-regions included in the temperature measurement region, or the temperature of a set of representative points included in the temperature measurement region.

[0032] For example, if two or more sound wave transmitters 13 and two or more sound wave receivers 14 are arranged as shown in Figure 3, the acquisition unit 15 may have sound wave transmitter 13a emit a pulsed sound wave at time t=0, and then measure the propagation times t1, t2, t3, and t4 of that sound wave at sound wave receivers 14b, 14c, 14d, and 14e, respectively. Similarly, the acquisition unit 15 may have sound wave transmitters 13b to 13f emit pulsed sound waves, respectively, and measure the propagation times from sound wave transmitter 13 to sound wave receiver 14, respectively, by specifying the reception times at each of the sound wave receivers 14a to 14f. In this case, for example, sound waves are emitted from each of the six sound wave transmitters 13, and the propagation time is measured for each sound wave according to the reception result at the four sound wave receivers 14, so a total of 24 propagation times are measured. The acquisition unit 15 may also repeat the measurement of the sound wave propagation time between the sound wave transmitters 13 and sound wave receivers 14 multiple times, and use a representative value from these multiple measurement results as the final propagation time to acquire the temperature distribution. The representative value may be, for example, the mean or median.

[0033] The acquisition unit 15 may use the propagation time measured in this manner to acquire the temperature distribution of the temperature measurement area by the CT method, for example, as follows. Here, assume that the temperature measurement area is divided into n sub-sections. Also, let A be a vector whose elements are the reciprocals of the propagation speed of the sound waves for each section. Vector A is a vector with n elements. Also, assume that m propagation times are measured using the sound wave reception results from two or more sound wave receivers 14. Let B be a vector whose elements are these propagation times. Vector B is a vector with m elements. Here, m and n are each integers of 2 or more. Also, assume that m is an integer of n or more. These vectors A and B satisfy the relationship shown in the following equation. B=HA

[0034] Here, matrix H is an m x n coefficient matrix, and each element is uniquely determined according to the arrangement of two or more sound wave transmitters 13 and two or more sound wave receivers 14, and the division of the temperature measurement area into n sub-sections. The acquisition unit 15 can use vector B, which is determined by the measured sound wave propagation time, and the above equation to identify vector A, that is, the sound wave propagation speed for each of the n sub-sections. In this case, for example, the sound wave propagation speed may be identified by the least squares method. Furthermore, the acquisition unit 15 can use the identified sound wave propagation speed and the relationship between the sound wave propagation speed and temperature to acquire the temperature for each of the n sub-sections, that is, the temperature distribution of the temperature measurement area.

[0035] The relationship between sound wave propagation speed and temperature may be obtained in advance, for example, by measuring the propagation time of sound waves while the object to be heated is heated to various temperatures and converting it to propagation speed. The range of temperatures to be measured in advance will differ depending on the purpose of microwave irradiation. For heating or drying, a range of room temperature (such as 20°C) to less than 300°C is possible; for firing or melting, a range of room temperature (such as 20°C) to less than 1500°C is possible; and for freezing or thawing, a range of -20°C to less than 30°C is possible. However, it is sufficient to obtain the necessary range in advance to acquire the temperature distribution of the object to be heated.

[0036] Furthermore, the method used to obtain the temperature distribution using image reconstruction is not limited. Here, as an example, we have described how to obtain the temperature distribution using the least squares method in back projection, but as another example, the temperature distribution may be obtained using a method other than the least squares method in back projection, or it may be obtained using a successive approximation method other than back projection.

[0037] The memory unit 16 may store a reference value for temperature. This reference value may be, for example, a value obtained by simulation, a theoretically obtained value, or a set value. The reference value may be, for example, a single value, or a value indicating a predetermined range. Furthermore, the reference value may be, for example, a value corresponding to the entire temperature measurement area, or a value for each section into which the temperature measurement area is divided. As an example, the smaller the difference between the value included in the acquired temperature distribution and the reference value, the more ideal microwave heating is being performed, and the larger the difference between the two values, the more unideal microwave heating is being performed.

[0038] The process by which information is stored in the storage unit 16 is irrelevant. For example, information may be stored in the storage unit 16 via a recording medium, information transmitted via a communication line or the like may be stored in the storage unit 16, or information input via an input device may be stored in the storage unit 16. The storage unit 16 is preferably implemented using a non-volatile recording medium, but it may also be implemented using a volatile recording medium. The recording medium may be, for example, a semiconductor memory, a magnetic disk, or an optical disk.

[0039] The anomaly detection unit 17 may detect anomalies by comparing the temperature distribution acquired by the acquisition unit 15 with reference values ​​stored in the storage unit 16. For example, an anomaly may be detected if the absolute value of the difference between at least one temperature included in the temperature distribution and the reference value is greater than a threshold, and not detected otherwise.

[0040] The microwave generator 18 generates microwaves to be introduced into the container 11. The microwave generator 18 may generate microwaves using, for example, a magnetron, klystron, gyrotron, or semiconductor element. Generating microwaves using a semiconductor element may, for example, involve oscillating microwaves using the semiconductor element, or amplifying microwaves using the semiconductor element. The frequency band of the microwaves may be, for example, around 433.92 MHz, 915 MHz, 2.45 GHz, and 5.8 GHz, or it may be any other frequency band within the range of 300 MHz to 300 GHz.

[0041] Microwaves generated by the microwave generator 18 are introduced into the container 11 by a waveguide 19. The waveguide 19 may be, for example, a hollow waveguide. A microwave-transparent window may be provided at the container 11 side end of the waveguide 19 or at another location to prevent the movement of vapor, particles, etc., from the inside of the container 11 to the microwave generator 18 side. This window may be made of, for example, a microwave-transparent material. The microwave-transparent material is not particularly limited, but may be, for example, quartz, glass, fluororesin such as polytetrafluoroethylene, ceramic, etc. Also, this window may be, for example, an airtight window or an airtight window. Microwave irradiation of the microwave absorber 12 is usually performed in multimode.

[0042] As an example, microwaves generated by the microwave generator 18 may be introduced into the container 11 by a coaxial cable instead of a waveguide 19. As another example, microwaves generated by the microwave generator 18 may be introduced directly into the container 11 without passing through a waveguide such as a waveguide or coaxial cable. Furthermore, although this embodiment mainly describes the case in which microwaves generated by two microwave generators 18 are introduced into the container 11, it goes without saying that microwaves generated by one or three or more microwave generators 18 may also be introduced into the container 11.

[0043] The control unit 20 controls the microwave generator 18 using the temperature distribution acquired by the acquisition unit 15. This control may be, for example, feedback control. In this case, the output of the microwave generator 18 may be controlled so that the representative value of the acquired temperature distribution falls within a predetermined range. The control unit 20 may also control the microwave generator 18 using the abnormality detection result from the abnormality detection unit 17. For example, if an abnormality is detected, the control unit 20 may stop the microwave generator 18 or reduce the microwave output from the microwave generator 18.

[0044] Next, the operation of the microwave heating apparatus 1 according to this embodiment will be described. First, raw materials are supplied into the container 11 from the supply port 11a. This supply of raw materials may be carried out continuously, for example. Microwaves are also irradiated onto the microwave absorber 12 inside the container 11 to heat it. The raw materials supplied from the supply port 11a pass through the microwave-heated microwave absorber 12, and the heating causes desired processing such as decomposition, and the processed material is discharged from the discharge port 11b.

[0045] While microwave heating is being performed in this manner, the acquisition unit 15 emits sound waves from the sound wave transmitter 13, receives these sound waves with two or more sound wave receivers 14, and measures the propagation time of each. The acquisition unit 15 repeatedly measures the propagation time of the sound waves while sequentially changing the sound wave transmitter 13 that emits the sound waves. Once the propagation time measurement is complete, the acquisition unit 15 uses the measured propagation time to acquire the temperature distribution of the temperature measurement area and can pass the acquired temperature distribution to the anomaly detection unit 17 and the control unit 20.

[0046] Upon receiving the temperature distribution, the abnormality detection unit 17 compares the received temperature distribution with a reference value stored in the memory unit 16. If the abnormality detection unit 17 detects an abnormality, it transmits that fact to the control unit 20. On the other hand, if no abnormality is detected, the abnormality detection unit 17 may transmit a message to the control unit 20 indicating that no abnormality was detected, or it may not.

[0047] Upon receiving the temperature distribution, the control unit 20 may use it to control the microwave generator 18. For example, the control unit 20 may perform feedback control so that a representative value, such as the average value of the temperature distribution, falls within a predetermined range. Furthermore, upon receiving notification that an abnormality has been detected, the control unit 20 may, for example, stop the microwave generator 18 and output a message indicating that an abnormality has been detected via an output unit (not shown). Note that the acquisition of the temperature distribution by the acquisition unit 15, the comparison of the temperature distribution with a reference value by the abnormality detection unit 17, and the control by the control unit 20 may be performed repeatedly.

[0048] As described above, the microwave heating device 1 according to this embodiment allows for the acquisition of the temperature distribution in the temperature measurement area inside the container 11 using sound waves, and enables the acquisition of temperature distributions other than the surface of the object being heated and specific locations. Therefore, the temperature distribution inside the object being heated, such as the microwave absorber 12, can also be acquired, and abnormalities such as thermal runaway occurring inside the object being heated can be detected more reliably. Furthermore, the acquired temperature distribution in the temperature measurement area can be used to control the microwave output more appropriately. For example, if the temperature at a specific location is higher than the target temperature, control may be performed to prevent microwaves from concentrating at that location. As an example, the control unit 20 may reduce the output of the microwave generator 18 that generates microwaves irradiated to the location where the temperature is high.

[0049] In this embodiment, the case where a two-dimensional temperature distribution of one temperature measurement area is acquired has been mainly described, but the temperature distributions of two or more temperature measurement areas may also be acquired. In this case, for example, two or more sound wave transmitters 13 and two or more sound wave receivers 14 may be arranged on the outer surface 11c of the container 11 along at least a portion of the periphery of each of two or more parallel temperature measurement areas. The acquisition unit 15 may then acquire the temperature distribution of each of these two or more temperature measurement areas. In this case, the acquisition unit 15 will acquire the temperature distribution of a temperature measurement area using the propagation time measured using two or more sound wave transmitters 13 and two or more sound wave receivers 14 arranged in at least a portion of the periphery of that temperature measurement area. Therefore, when acquiring the temperature distribution for two or more temperature measurement areas, the acquisition unit 15 will repeat the process of acquiring the temperature distribution for each temperature measurement area. When a two-dimensional temperature distribution is acquired for each of two or more parallel temperature measurement areas, and the distance between the two or more temperature measurement areas is short, it is essentially the case that a three-dimensional temperature distribution is acquired.

[0050] Figure 6 shows an example of sound wave transmitters 13 and sound wave receivers 14 arranged on the outer surface 11c of the container 11 along the periphery of each of three parallel temperature measurement regions. As shown in Figure 6, when two or more sound wave transmitters 13 and two or more sound wave receivers 14 are arranged at positions X=X1, X2, and X3 in the X-axis, which is a first direction perpendicular to the plane direction of the temperature measurement region, the acquisition unit 15 can acquire the temperature distribution of the temperature measurement region at each of the positions X=X1, X2, and X3. For example, when the distance between X1, X2, and X3 is small, it becomes possible to acquire a substantially three-dimensional temperature distribution. Here, we have described the case of acquiring the temperature distribution for each of three parallel temperature measurement regions, but it goes without saying that the temperature distribution may also be acquired for two parallel temperature measurement regions, or for each of four or more parallel temperature measurement regions.

[0051] Furthermore, in this embodiment, the temperature distribution of the temperature measurement area may be obtained at multiple positions in a first direction perpendicular to the plane direction of the temperature measurement area by moving two or more sound wave transmitters 13 and two or more sound wave receivers 14. In this case, the microwave heating device 1 may further include a moving mechanism 30 for moving the two or more sound wave transmitters 13 and two or more sound wave receivers 14 in the first direction. The configuration is not limited as long as it is possible to move two or more sound wave transmitters 13 and two or more sound wave receivers 14, but the moving mechanism 30 may, for example, have a support part 31 that supports two or more sound wave transmitters 13 and two or more sound wave receivers 14, a plurality of rails 32 attached to the outer surface 11c of the container 11 with its longitudinal direction being the first direction, a plurality of sliders 33 that are slidably assembled to the plurality of rails 32, a rack gear 34 fixed to the support part 31 with its longitudinal direction being the first direction, a pinion gear 35 provided to engage with the rack gear 34, and a drive unit 36 ​​such as a motor that rotates the pinion gear 35. Here, Figure 7 is a schematic diagram showing the external appearance of the container 11, and Figure 8 is a cross-sectional view taken along line VIII-VIII in Figure 7.

[0052] The support section 31 is cylindrical in shape, and two or more sound wave transmitters 13 and two or more sound wave receivers 14 are fixed to its inner circumferential surface. The two or more sound wave transmitters 13 and two or more sound wave receivers 14 fixed to the support section 31 are each in contact with the outer surface 11c of the container 11. A slider 33 is also fixed to the inner circumferential surface of the support section 31, allowing the support section 31 to move in a first direction along multiple rails 32. Furthermore, the rotation of the pinion gear 35 by the drive unit 36 ​​causes the rack gear 34 and the support section 31 to move in the first direction.

[0053] Here, the linear actuator that moves the support portion 31 in the first direction is shown as having a rack and pinion mechanism and a drive unit 36 ​​that rotates the pinion gear 35, but it goes without saying that the linear actuator may have other configurations. For example, the linear actuator may have a ball screw mechanism and a drive unit that rotates the screw shaft of the ball screw mechanism, or it may have a pair of pulleys, an endless belt stretched between the pair of pulleys, and a drive unit that rotates the pulleys, or it may use a sprocket and a chain instead of the pulleys and belt, or it may have other configurations.

[0054] In this case, the acquisition unit 15 may acquire the temperature distribution of the temperature measurement area at multiple positions in the first direction. For example, the acquisition unit 15 may control the drive unit 36 ​​so that two or more sound wave transmitters 13 and two or more sound wave receivers 14 are at position X1, acquire the temperature distribution of the temperature measurement area at X1, and similarly acquire the temperature distribution of the temperature measurement areas at X2 and X3. In this way, it becomes possible to acquire the temperature distribution of the temperature measurement area at each of the multiple positions in the first direction, even if two or more sound wave transmitters 13 and two or more sound wave receivers 14 are not arranged at each of the multiple positions. It goes without saying that the moving mechanism 30 may have a configuration other than those shown in Figures 7 and 8, as long as it can move two or more sound wave transmitters 13 and two or more sound wave receivers 14 in the first direction.

[0055] Furthermore, in this embodiment, when two or more sound wave transmitters 13 and two or more sound wave receivers 14 are arranged in a ring shape on the outer surface of the container 11 so as to surround the temperature measurement area, the case in which they are alternately arranged along the periphery of the temperature measurement area, as shown in Figure 3, has been described, but this is not required. Figures 9 and 10 are cross-sectional views of the container 11 showing another example of the arrangement of sound wave transmitters 13 and sound wave receivers 14. For example, as shown in Figure 9, two or more sound wave transmitters 13 may be arranged in a part of the area along the periphery of the temperature measurement area, and two or more sound wave receivers 14 may be arranged in another area along the periphery of the temperature measurement area. Also, even when the temperature measurement area is not circular but rectangular, as shown in Figure 10, two or more sound wave transmitters 13 may be arranged along two adjacent sides of the rectangular temperature measurement area, and two or more sound wave receivers 14 may be arranged along two sides opposite to the two sides on which the two or more sound wave transmitters 13 are arranged. Thus, for example, two or more sound wave transmitters 13 and two or more sound wave receivers 14 may be arranged facing each other. In this case as well, it is preferable that the two or more sound wave transmitters 13 and two or more sound wave receivers 14 be arranged such that a wider range of the temperature measurement area is covered by the propagation path of the sound waves transmitted from the sound wave transmitters 13 and received by the sound wave receivers 14. Alternatively, as shown in Figures 3, 9, and 10, two or more sound wave transmitters 13 and two or more sound wave receivers 14 may be arranged such that at least one of the sound wave transmitters 13 and sound wave receivers 14 is present around the entire circumference of the temperature measurement area.

[0056] Here, we will describe an example of control performed for the case where the temperature distribution or a partial temperature distribution obtained from measurement results using sound waves is one-dimensional, two-dimensional, and three-dimensional. A one-dimensional temperature distribution can be obtained, for example, by identifying the one-dimensional temperature distribution along a desired direction in the two-dimensional temperature distribution obtained from measurement results using sound waves. The acquisition of two-dimensional and three-dimensional temperature distributions is as described above.

[0057] For example, if the one-dimensional temperature distribution includes areas with temperatures below a first threshold, control may be performed to increase the intensity of microwaves irradiated to those areas. This control may be performed, for example, by controlling the direction of microwaves output from a waveguide or antenna so that microwaves are irradiated towards areas where an increased microwave intensity is desired, or by controlling the phase difference of two or more microwaves so that microwaves are concentrated at areas where an increased microwave intensity is desired. In the former case, for example, a mechanism for changing the direction of the waveguide or antenna may be provided in the container 11. The direction of microwaves output from the waveguide or antenna may then be changed by controlling this mechanism according to the one-dimensional temperature distribution. As another example, if the one-dimensional temperature distribution includes areas with temperatures above a second threshold, control may be performed to decrease the intensity of microwaves irradiated to those areas. This control may be performed, for example, by controlling the direction of microwaves output from a waveguide or antenna so that microwaves are not directed towards areas where the intensity of the irradiated microwaves is to be reduced, or by controlling the phase difference between two or more microwaves so that microwaves are not concentrated in areas where the intensity of the irradiated microwaves is to be reduced. The second threshold may be, for example, a value greater than the first threshold. Furthermore, the control of the direction of the output microwaves or the control of the phase difference between two or more microwaves may be performed, for example, by the control unit 20.

[0058] Furthermore, for example, if the two-dimensional temperature distribution includes areas with temperatures below a first threshold, the microwave intensity irradiated to those areas may be controlled to be greater. As another example, if the two-dimensional temperature distribution includes areas with temperatures above a second threshold, the microwave intensity irradiated to those areas may be controlled to be less. These controls, like the control using a one-dimensional temperature distribution, may be performed, for example, by controlling the direction of the output microwaves or by controlling the phase difference between two or more microwaves.

[0059] Furthermore, for example, if the three-dimensional temperature distribution includes areas with temperatures below a first threshold, the microwave intensity irradiated to those areas may be controlled to be greater. As another example, if the three-dimensional temperature distribution includes areas with temperatures above a second threshold, the microwave intensity irradiated to those areas may be controlled to be less. These controls, like the control using a one-dimensional temperature distribution, may be performed, for example, by controlling the direction of the output microwaves or by controlling the phase difference between two or more microwaves.

[0060] Furthermore, although this embodiment mainly describes the case where the microwave heating device 1 is equipped with an abnormality detection unit 17, this is not required. If abnormality detection is not performed, the microwave heating device 1 does not need to be equipped with an abnormality detection unit 17.

[0061] Furthermore, although this embodiment mainly describes the case where the microwave heating device 1 is equipped with a microwave generator 18 and a waveguide 19, this is not required. The microwave heating device 1 does not need to be equipped with a microwave generator 18 and a waveguide 19. In this case, microwaves generated by a device other than the microwave heating device 1 may be introduced into the container 11.

[0062] Furthermore, although this embodiment mainly describes the case where the microwave heating device 1 is equipped with a control unit 20, this is not required. The microwave heating device 1 does not need to be equipped with a control unit 20. In this case, the microwave heating device 1 may be configured to introduce microwaves of a predetermined intensity into the container 11, or the intensity of the microwaves introduced into the container 11 may be controlled by an external control unit. In the latter case, for example, the temperature distribution acquired by the acquisition unit 15 may be provided to the external control unit.

[0063] Furthermore, although this embodiment mainly describes the case where the microwave absorber 12 is placed inside the container 11 and the temperature measurement area is a part of the microwave absorber 12, this is not required. The microwave absorber 12 does not have to be placed inside the container 11. For example, when heating a solid or liquid object with microwaves, the microwave absorber 12 does not have to be placed inside the container 11. In this case, a part of the solid or liquid may be the temperature measurement area. Examples of solids include ore, catalysts, refractories, and activated carbon. Examples of solids include powder, spherical, pellet, briquette, and rectangular shapes. Examples of liquids include suspensions, highly viscous liquids, and molten liquids.

[0064] Furthermore, the embodiments described above are illustrative examples for specifically carrying out the present invention and do not limit the technical scope of the present invention. The technical scope of the present invention is indicated by the claims rather than by the description of the embodiments, and modifications within the literal scope and equivalent meaning of the claims are intended. [Explanation of symbols]

[0065] 1. Microwave heating device 11 Container 12 Microwave absorbers 13, 13a~13f Sound wave generators 14, 14a~14f Sound wave receiver 15 Acquisition Department 16 Memory section 17 Anomaly detection unit 18 Microwave generator 19 Waveguide 20 Control Unit 30 Moving mechanism

Claims

1. A container for heating the object to be heated inside by microwave irradiation, Two or more sound wave transmitters are positioned on the outer surface of the container along at least a portion of the periphery of the temperature measurement area where at least a portion of the object to be heated is placed, and emit sound waves toward the inside of the container. Two or more sound wave receivers are arranged on the outer surface of the container along at least a portion of the periphery of the temperature measurement area and receive sound waves emitted by the two or more sound wave transmitters. A microwave heating device equipped with the following features.

2. A microwave heating apparatus according to claim 1, The two or more sound wave transmitters and the two or more sound wave receivers are arranged in an annular shape on the outer surface of the container.

3. A microwave heating apparatus according to claim 1 or 2, The system further includes an acquisition unit that acquires the temperature distribution inside the object to be heated using the propagation time of each sound wave transmitted by the two or more sound wave transmitters and received by the two or more sound wave receivers.

4. A microwave heating apparatus according to claim 3, The acquisition is performed using the relationship between propagation speed and temperature, which is obtained by measuring the propagation speed of sound waves while the object to be heated is heated to multiple temperatures.

5. A microwave heating apparatus according to claim 3 or 4, The aforementioned acquisition is performed using the CT method.

6. The method according to claim 4 or 5, The object to be heated includes solids.

7. The method according to claim 4 or 5, The object to be heated includes a liquid.

8. A microwave heating apparatus according to any one of claims 1 to 7, The system further includes a moving mechanism for moving the two or more sound wave transmitters and the two or more sound wave receivers in a first direction which is perpendicular to the plane direction of the temperature measurement area.

9. A microwave heating apparatus according to any one of claims 3 to 7, further comprising a moving mechanism for moving the two or more sound wave transmitters and the two or more sound wave receivers in a first direction which is perpendicular to the plane direction of the temperature measurement area, The acquisition unit acquires the temperature distribution of the temperature measurement area at multiple positions in the first direction.

10. A step of transmitting sound waves toward the inside of a container by two or more sound wave transmitters, which are positioned on the outer surface of a container along at least a portion of the periphery of a temperature measurement area where at least a portion of the object to be heated is placed, for heating the object to be heated inside the container by microwave irradiation, The steps include receiving sound waves emitted by the two or more sound wave transmitters using two or more sound wave receivers arranged on the outer surface of the container along at least a portion of the periphery of the temperature measurement area, A step of obtaining the temperature distribution inside the object to be heated using the propagation time of sound waves transmitted by the two or more sound wave transmitters and received by the two or more sound wave receivers. A method for obtaining temperature distribution, including the following.

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