Accurate temperature control reaction kettle microwave heating system and method thereof

Abstract

This invention discloses a microwave heating system for a precision temperature-controlled reactor, comprising: a microwave power radiator including at least two antenna units arranged around the reactor for radiating microwave energy into the reactor; a multiplexed feed network having multiple independent branches, each branch connected to one of the antenna units, and configured to selectively direct energy to the corresponding branch and antenna unit according to the frequency of the input microwave; a controllable power source connected to the input of the multiplexed feed network for generating microwave energy with adjustable frequency and power; a stirrer disposed inside the reactor for stirring materials; and a temperature sensor for monitoring the temperature of the materials inside the reactor. The controllable power source is configured to: select and activate different antenna units by adjusting the frequency of the output microwave based on the feedback signal from the temperature sensor and a preset temperature curve, and control the heating intensity by adjusting the power of the output microwave, thereby achieving zoned closed-loop heating of the materials inside the reactor.

Description

Technical Field

[0001] This invention relates to the field of microwave heating technology, specifically to a precision temperature-controlled reaction vessel for chemical reactions or material extraction, particularly suitable for the extraction of tobacco aroma substances. Background Technology

[0002] Microwave heating technology is widely used in chemical, food, pharmaceutical, and materials processing fields due to its advantages such as fast heating speed, high energy efficiency, and ease of control. In processes such as the extraction of tobacco aroma substances, the materials are extremely sensitive to temperature, requiring not only a controllable heating rate but also a high degree of temperature uniformity within the reactor to avoid localized overheating that could lead to component decomposition, carbonization, or oxidation, thereby affecting the yield and quality of the final product.

[0003] Traditional microwave heating devices for reactors typically employ a single or a few fixed microwave feed inlets. This design easily leads to uneven microwave field distribution within the reactor, creating hot and cold spots and causing uneven heating of the materials. Although this can be improved by stirring, for materials whose dielectric properties change with temperature and composition, stirring alone is insufficient to achieve precise temperature control, especially when pursuing complex temperature process curves (such as multi-stage heating and isothermal processes). It is difficult to ensure that the materials throughout the entire reaction volume synchronously and accurately follow the set curve.

[0004] In existing technologies, some solutions have proposed multi-feed designs or modal stirrers to improve uniformity. However, multi-feed designs often imply multiple independent microwave sources or complex waveguide switching systems, resulting in high costs and complex control. While modal stirrers can change the field pattern over time, their regulation is random and passive, unable to actively and directionally compensate for temperature non-uniformity detected in real time within the reactor.

[0005] In addition, conventional microwave antennas or radiators usually use dielectric substrates such as ceramics, whose dielectric properties may change at high temperatures, increasing energy loss. Long-term operation at high temperatures may lead to performance degradation or damage, limiting their application in high-temperature (up to 300°C) processes such as tobacco dry distillation.

[0006] Therefore, there is an urgent need for a new type of microwave heating system that can independently and precisely control the heating power of different areas inside the reactor, structurally ensure heating uniformity, and has good high-temperature adaptability and process flexibility. Summary of the Invention

[0007] This invention aims to overcome the shortcomings of existing technologies and provide a microwave heating system for a precision temperature-controlled reactor. This system combines frequency control with spatial partitioning heating through a unique microwave power radiator array layout and a multi-function power supply network design, achieving uniform and precise temperature control of materials within the reactor.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A precision temperature-controlled microwave heating system for a reactor includes: a microwave power radiator comprising at least two antenna units arranged around the reactor for radiating microwave energy into the reactor; a multiplexer feed network having multiple independent branches, each branch connected to one of the antenna units, and configured to selectively direct energy to the corresponding branch and antenna unit according to the frequency of the input microwave; a controllable power source connected to the input of the multiplexer feed network for generating microwave energy with adjustable frequency and power; a stirrer disposed within the reactor for stirring materials; and a temperature sensor for monitoring the temperature of the materials within the reactor. The controllable power source is configured to: select and activate different antenna units by adjusting the frequency of the output microwave based on the feedback signal from the temperature sensor and a preset temperature curve, and control the heating intensity by adjusting the power of the output microwave, thereby achieving zoned closed-loop heating of the materials within the reactor.

[0009] Furthermore, the antenna unit adopts an air-substrate patch antenna, which includes a patch antenna structure printed on a metal radiating surface, and an air dielectric layer is formed between the metal radiating surface and the ground plane.

[0010] Furthermore, each independent branch of the multiplexed power supply network is configured to exhibit low-loss transmission characteristics for microwave energy near a specific center frequency, and the isolation between branches is not less than 20dB.

[0011] Furthermore, the controllable power source is further configured to run a PID control algorithm, which dynamically adjusts the output power to make the heating rate of the material controllable within the range of 0-20℃ / min, and to ensure that the temperature error during the constant temperature stage does not exceed ±4℃.

[0012] Furthermore, the controllable power source is further configured to: when the temperature sensor detects that the temperature difference between different areas inside the reactor exceeds 10°C, adjust the radiation intensity of the antenna unit in the corresponding area by switching the output frequency.

[0013] Furthermore, it also includes a microwave shield and a microwave leakage detector. When the detected microwave leakage exceeds 0.4 W / m², the controllable power source is configured to cut off the microwave energy output.

[0014] Furthermore, the reactor is made of quartz glass or special ceramics, and the antenna unit is fixed by an adjustable mounting bracket. The distance between the radiating surface of the antenna unit and the outer wall of the reactor is adjusted to within the range of 8-12 cm.

[0015] Furthermore, the stirrer is a magnetic stirrer with an adjustable speed in the range of 50-200 r / min.

[0016] A microwave heating method using any of the systems described herein includes the following steps: S1: parameter preset, inputting process parameters including multiple custom temperature curves; S2: zone heating control, dynamically adjusting the frequency and power of the output microwaves through the controllable power source based on the preset curves and real-time feedback from the temperature sensors; wherein, by switching the output frequency, microwave energy is selectively directed to different antenna units via the multiplexer feed network to achieve differentiated heating of different sectors within the reactor; S3: homogenization treatment, activating the stirrer to agitate the materials during the heating process, combined with the zone heating control in step S2, to ensure that the temperature of the materials within the reactor rises uniformly and follows the preset curve.

[0017] Furthermore, in step S2, the controllable power source adopts a time-slice polling or temperature deviation-driven strategy to determine the timing and order of switching the output frequency to activate different antenna elements.

[0018] The present invention has the following beneficial technical effects: 1. Precise Zoned Heating Based on Frequency-Spatial Mapping: This invention establishes a one-to-one mapping between the frequency and spatial dimensions through a multiplexed feed network. This allows a single controllable power source to unambiguously select and feed any specific antenna unit around the reactor simply by changing its output frequency, thereby naturally dividing the internal space of the reactor into multiple independent heating sectors corresponding to the locations of these antenna units. Compared to traditional solutions that require multiple independent microwave sources or mechanical waveguide switchers, this invention achieves true spatial zoned independent temperature control at extremely low hardware costs, with material temperature differences stably controlled within 10°C.

[0019] 2. Strong process adaptability: The system supports flexible selection and activation of one or more heating sectors through frequency switching. With power adjustment, it can easily meet the needs of different process stages from low-temperature dehydration to high-temperature dry distillation (room temperature to 300℃). The heating rate can be precisely controlled within the range of 0-20℃ / min, making it suitable for large-scale industrial production and small-batch scientific research experiments.

[0020] 3. Good high-temperature stability: The air substrate patch antenna utilizes the low loss and high temperature resistance of air to ensure the stable performance and long life (expected to be more than 5 years) of the radiator itself under high temperature conditions, overcoming the shortcomings of traditional dielectric substrates that are prone to degradation at high temperatures.

[0021] 4. Intelligent and Precise Control: Without requiring multiple independent microwave sources or mechanical waveguide switching devices, the system utilizes a single controllable microwave source combined with the inherent frequency selectivity of a passive power supply network to establish a "frequency-space" mapping relationship. This enables independent and precise control of the heating power in different spatial sectors within the reactor. Combining this "frequency-space" mapping with closed-loop temperature feedback control achieves a leap from "passive uniform stirring" to "active zone compensation." Based on real-time temperature monitoring data, the system intelligently adjusts the heating intensity of different areas, ensuring the material temperature more closely follows a complex preset curve.

[0022] 5. Safe and reliable: The integrated metal shielding cover and online leakage detection ensure that the microwave leakage is far below the national standard (≤0.4W / m²), ensuring the safety of operators; the modular design facilitates maintenance. Attached Figure Description

[0023] The above description of the present invention and the following detailed embodiments will be better understood when read in conjunction with the accompanying drawings. It should be noted that the drawings are merely examples of the claimed technical solutions.

[0024] Figure 1 This is a structural block diagram of the microwave heating system for a precision temperature-controlled reactor described in this invention, illustrating the connection and control relationships between the various components of the system.

[0025] Figure 2 This is a schematic diagram of the antenna unit structure of a microwave power radiator in one embodiment of the present invention.

[0026] Figure 3 This is an example of a Smith chart used to explain the frequency selection characteristics of a multiplexed feeder network in one embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the connection structure between the multiplexed feed network and the antenna unit array in one embodiment of the present invention.

[0028] The reference numerals in the attached figures are explained as follows: 1 Controllable power source 2 Multiplexed power supply network 3. Reactor 4. Stirrer 5. Temperature sensor 6. Central Control Module 7 Antenna element #1 (center frequency f1) 8 Antenna element #2 (center frequency f2) 9 Antenna element #3 (center frequency f3) Antenna element #4 (center frequency f4) 11 Patch Antenna 12 Common power supply points 13 Radiation Surface 14 cavities 15 Impedance Matching Points 16 Impedance Trajectory Detailed Implementation

[0029] The following detailed description of the features and advantages of the present invention is sufficient to enable any person skilled in the art to understand the technical content of the present invention and implement it accordingly. Furthermore, based on the specification, claims and drawings disclosed herein, those skilled in the art can easily understand the related objects and advantages of the present invention.

[0030] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] For ease of understanding, the directional terms such as "upper," "lower," "top," and "bottom" used in this manual are based on the upright position of the aerosol generating device.

[0032] like Figure 1 As shown, the precision temperature-controlled microwave heating system for chemical reactors (especially for extracting tobacco aroma substances) described in this invention is a specialized device that provides uniform and precise microwave heating for chemical reactors. Its technical focus is on two main application scenarios: in industrial production, it is suitable for reactors with a feed volume ≥ 50L, providing energy for the dehydration, medium-temperature extraction, and high-temperature dry distillation of tobacco aroma substances; in scientific research, it can be adapted to small samples of 100g-5kg through parameter fine-tuning, meeting process optimization requirements. Its core design concept combines "spatial partitioning" and "frequency addressing," meaning that the controllable power source 1, through the inherent selective response of each branch of the multiplexed feed network 2 to different center frequencies, maps the single-dimensional control variable of frequency to the spatial position variable of the antenna element around the reactor 3. Specifically, when the controllable power source 1 outputs microwaves of a certain frequency, the multiplexed feed network 2 only allows the branch corresponding to that frequency to present a low-loss path, while the other branches are in a high-resistance state, thereby directionally distributing microwave energy to the specific antenna element bound to that frequency, achieving selective heating of the corresponding spatial sector within the reactor. This mechanism allows a single microwave source to independently deliver power to multiple spatial regions without the need for parallel multi-source connections or mechanical switching. Combined with real-time feedback from temperature sensor 5 and material mixing by stirrer 4, it ultimately achieves uniform and rapid heating of the entire material within the reactor and precise tracking of complex temperature process curves, while ensuring that the system's microwave leakage meets national standards (≤0.4W / m²).

[0033] The microwave power radiator is the energy transmission terminal of the system, and its design directly determines the efficiency and spatial uniformity of microwave energy entering the reactor. For example... Figure 1 As shown, each antenna element consists of multiple patch antennas 11 connected in parallel. Patch antennas are a common type of planar antenna in microwave engineering, and their radiation principle is based on the resonant cavity formed between the microstrip patch and the ground plane. The key improvement of this invention lies in the "air substrate" design. Specifically, the following structure can be adopted: the patch antennas 11 are printed or etched on a thin radiating surface 13 made of a low-loss rigid metal (such as polished aluminum or copper), which is suspended and fixed above the metal ground plane by insulating supports, and the gap between the two is the "air substrate". All patch antennas 11 are arranged coplanarly and at equal intervals within the element to form a compact radiating array, thereby widening the beamwidth and improving the radiation pattern. Figure 2In one embodiment shown, each unit can integrate three patch antennas 11, arranged coplanarly with adjacent spacing of 90 degrees. The feed lines (microstrip lines or coaxial lines) of all patch antennas 11 within the unit are physically converged and connected to a common feed point 12. This design ensures that all patch antennas 11 within the unit are synchronously excited, phase-consistent, and radiation-coordinated. Air has near-ideal lossless characteristics (dielectric constant ε_r≈1, loss tangent tanδ≤0.001). Using air as the equivalent substrate brings significant advantages: First, the antenna's own ohmic loss and dielectric loss are extremely low, with measured energy transmission loss controllable below 2%, far lower than traditional antennas using ceramic or polymer substrates (losses typically ≥8%); second, the dielectric properties of air are extremely stable over a wide temperature range (-50℃ to above 300℃), avoiding the antenna performance degradation or even failure caused by dielectric constant drift and increased loss at high temperatures in conventional dielectric substrates. This allows the radiator to be fully adapted to high-temperature processes such as tobacco distillation, with an expected service life of over 5 years. Multiple antenna elements are arranged around the outer perimeter of the cylindrical reactor 3. The number of elements can be flexibly selected according to the diameter of the reactor 3 and the required heating uniformity accuracy: for example, two elements are arranged symmetrically at 180°, dividing the reactor 3 into two sectors; three elements are arranged at 120° intervals, dividing into three sectors; and four elements are arranged at 90° intervals, dividing into four sectors. Theoretically, the more elements there are, the finer the partitioning, and the higher the potential for uniformity control, but the system complexity also increases accordingly. For common 50L industrial reactors, two or three elements are sufficient to achieve excellent results; for small reactors used in scientific research, two elements are enough. This multi-element surrounding layout ensures irradiation of the reactor 3 from all directions, achieving 360° radiation without dead angles and eliminating "shadow areas" or hot spots caused by single-sided feeding. The antenna elements adopt a modular, disassembled design, making replacement simple and requiring no professional microwave technicians for maintenance. The antenna elements are fixed using dedicated mounting brackets. The support is made of high-temperature resistant, low-dielectric-loss insulating materials such as polytetrafluoroethylene or special ceramics. Its mechanical structure allows for precise adjustment of the distance between the antenna element radiating surface 13 and the outer wall of the reactor 3 (typically adjustable within the range of 8-12 cm) and the azimuth accuracy of the surround (deviation ≤1°). The optimization of this distance depends on the dielectric constant and thickness of the reactor 3 wall material, with the aim of achieving good impedance matching between the antenna and the reactor load to maximize energy transfer efficiency (for quartz glass reactors, transmittance ≥95%).

[0034] The multiplexing feed network 2 is the system's "traffic hub," responsible for distributing microwave energy from a single source to different antenna elements according to their frequency "addresses." For example... Figure 4As shown, the multiplexed feed network 2 is a microwave passive device with a common input and multiple independent output branches. Each branch integrates a filtering network (such as a bandpass filter designed using striplines or microstrip lines), ensuring that each branch exhibits very low insertion loss only for a narrow frequency band centered at a specific center frequency (e.g., f1, f2, ..., fn), while exhibiting high attenuation for the center frequencies of other branches. Figure 3 As shown in the Smith chart example, each branch achieves perfect matching (center) at its center frequency point through impedance transformation, but rapidly mismatches when deviating. When the controllable power source 1 outputs a microwave signal at frequency f1, the multiplexed feed network, based on the frequency selectivity of its branch filter networks, allows the signal to pass through the corresponding branch with almost no attenuation and be transmitted to the antenna element connected to it. Simultaneously, other branches present high input impedance to this frequency signal, forming a blocking state, thus forcibly and efficiently transmitting microwave energy to the antenna element connected to that branch. At this time, sector 1 corresponding to that element is mainly activated. Similarly, switching the frequency to f2 mainly activates sector 2. Thus, the system establishes a defined "frequency-space" mapping relationship between the controllable power source and the antenna elements around the reactor: frequency f1... Branch 1 Antenna Unit #1 Reactor sector 1, frequency f2 Branch 2 Antenna Unit #2 The process continues in sector 2 of the reactor. Isolation between branches is a key performance indicator, requiring a minimum of 20dB and energy crosstalk ≤5%. High isolation ensures that when one branch is activated, the impedance mismatch seen at the inputs of other branches is severe, with only a very small amount of energy leaking or coupling to non-target branches, thus guaranteeing the "purity" and independent controllability of the zoned heating. The multiplexed feeder network 2 can be implemented using mature microwave circuit technology, such as parallel multi-channel filter banks based on microstrip lines. Its design is a routine task that can be completed by those skilled in the art based on the required center frequency, bandwidth, and isolation specifications.

[0035] The controllable power source 1 is a microwave signal generator capable of producing microwave signals with continuously adjustable frequency and power, or adjustable at discrete points, and possesses digital control and human-machine interaction functions. Its core functions include: generating continuous-wave microwaves with an adjustable frequency within a predetermined range (e.g., the 2.4-2.5 GHz ISM band) and adjustable power from 0 to the rated maximum value; receiving signals from one or more temperature sensors 5 within the reactor 3; running a control algorithm, specifically a PID control algorithm, comparing the real-time temperature with a user-preset temperature-time curve to calculate the required microwave power and / or frequency adjustment; and providing a graphical interface for users to input process parameters and monitor process data, achieving integrated control of "drive + monitoring + human-machine interaction." The controllable power source 1 integrates the core control logic for implementing the method of this invention. It adjusts the power based on the overall average temperature and, further, can identify the physical sector corresponding to the feedback from the temperature sensor 5. For example, if the sensor shows that the temperature of sector 1 is lower than the set value, while the temperature of sector 2 has reached the set value, the controller can prioritize switching the frequency to f1 and appropriately increase the power to focus on heating sector 1; or, after the temperature of sector 2 reaches the set value, immediately switch the frequency from f2 to the frequency corresponding to other sectors with lower temperatures. This spatially differentiated closed-loop control is key to achieving highly uniform heating. The microwave output terminal of the controllable power source 1 is connected to the common input terminal of the multiplexed power supply network 2; its digital interface is connected to the temperature sensor 5, the stirrer 4 motor driver, the microwave leakage detector, etc.

[0036] Reactor 3 is the material container. For efficient microwave transmission, at least the parts of the vessel body in contact with microwave radiation should be made of materials with low microwave loss, high temperature resistance, and chemical corrosion resistance, such as quartz glass, special ceramics, or certain high-performance polymers. The geometry of reactor 3 should match the number and layout of antenna units to ensure that the radiation field of all antenna units effectively covers the entire material area without any "blind spots." The system can be equipped with a series of reactors 3 of varying volumes for replacement to suit different scenarios. The stirrer 4 is an important auxiliary means to achieve final homogeneity. A top-driven magnetic stirrer is typically used, with a wide speed range (e.g., 50-200 rpm). The purpose of stirring is to continuously move the material, periodically exposing it to microwave irradiation in different sectors, and accelerating heat transfer within the material through forced convection. Stirring and microwave zoned heating are complementary: zoned heating macroscopically reduces regional temperature differences, while stirring microscopically smooths out local temperature differences, jointly ensuring that the temperature difference between the heated material areas within reactor 3 is ≤10℃.

[0037] Safety and shielding components include a metal shield, a microwave leakage detector, and a heat dissipation assembly. Each antenna unit is fitted with a sealed metal shield (such as 304 stainless steel), forming a double shield with the equipment housing. Its function is to strictly confine microwaves within the shield, allowing energy to be emitted only from the radiating surface 13 towards the reactor 3. Microwave radiation probes are installed outside the shield or at key points on the equipment housing to continuously monitor environmental leakage levels. Once the detected value exceeds the public exposure limit (0.4 W / m²) stipulated by the national mandatory standard, the system will immediately issue an audible and visual alarm and cut off the microwave output. At high-power nodes in the microwave energy transmission path, such as the common connector of the multiplexed feeder network 2 and near the final stage power amplifier of the controllable power source 1, air-cooled or water-cooled heat dissipation structures are installed to avoid parameter drift caused by localized overheating and ensure that key components operate at suitable temperatures.

[0038] Combination Figure 1The complete workflow of the system's overall structure embodiment shown is as follows: First, system configuration and initialization are performed: Based on the volume and diameter of the target reactor 3, a suitable number of antenna units are selected and uniformly installed and fixed around the reactor 3 using mounting brackets, with precise adjustment of distance and angle; the multiplexer feed network 2 is connected, with its common terminal connected to the microwave output of the controllable power source 1, and its multiple output terminals connected to the common feed point 12 of each antenna unit; all signal lines are connected, including the temperature sensor 5, the stirrer 4 driver, the leak detector, etc.; the system performs a power-on self-test. Next, the user inputs process parameters, including material parameters (type, quality, moisture content), multiple custom temperature curves, stirring parameters, and safety parameters (such as a maximum temperature limit of 300℃). The system supports independent / cooperative working modes, and the user can preset the number of units to be started and the power level according to the process stage (such as low-temperature dehydration, medium-temperature extraction, high-temperature distillation). After startup, the system enters the zoned closed-loop heating stage: Controllable power source 1 outputs microwaves at an initial frequency and an initial power calculated based on material parameters. Energy is fed into the corresponding antenna unit through multiplexer network 2, primarily heating one sector. Simultaneously, stirrer 4 starts operating. Temperature sensors 5 sample at a frequency of at least once per second, and the controller assigns the sensor readings to the corresponding physical sector based on the sensor's installation location. The control loop includes sector-level PID control and a frequency-modulated sector addressing strategy. Since each antenna unit is uniquely bound to a specific frequency by the multiplexer network, the heating control of a particular sector is physically manifested as the controllable power source outputting a microwave signal at the frequency corresponding to that sector. Based on the deviation between the temperature feedback and the setpoint of each sector, the controller adjusts the output microwave frequency in real time, achieving on-demand, real-time addressing and energy delivery to different sectors. Specific strategies can employ a time-slice polling method, periodically switching between frequencies to ensure each sector receives heating sequentially according to its time quota; or a temperature deviation-driven strategy, locking the current output frequency to the frequency corresponding to the sector with the largest temperature deviation, achieving deviation-priority directional energy compensation. Throughout the process, stirrer 4 continuously operates, agitating materials from heavily heated sectors to less heated areas, physically mixing temperatures. The controller continuously records all process data, forming a complete process log. The system features parallel multi-threaded safety monitoring: if the temperature at any point exceeds 300℃, the microwave power is immediately reduced to zero and an alarm is triggered; if microwave leakage exceeds the limit, power is immediately cut off; if the stirrer 4 speed signal is lost or falls below a safe value, an alarm is triggered and microwave power may be reduced to prevent localized overheating of stationary materials; the system is equipped with an uninterruptible power supply, which automatically saves the current process status and all data in the event of an unexpected power outage.

[0039] An example using a 50L tobacco extraction system equipped with three antenna units is illustrated, demonstrating significant effectiveness. This system, through an array layout and low crosstalk feeding, ensures an energy density difference within reactor 3 of ≤1.2:1. During extraction, temperature monitoring at different locations within reactor 3 shows that the material temperature difference remains consistently within 10℃ (ideally 6-8℃), completely eliminating the temperature gradient and localized overheating problems caused by traditional single-antenna heating. The system can accurately track complex multi-segment heating-isothermal curves, with temperature fluctuations during the isothermal phase controlled within ±2℃. When applied to tobacco aroma extraction, compared to traditional reflux methods, the loss rate of effective components can be reduced from 25%-30% to below 10%, batch-to-batch quality deviation of extracts is ≤5%, while extraction time is shortened and the extraction rate of target components is increased. In high-temperature dry distillation experiments, the air-based antenna exhibits stable performance, and the system operates reliably. The microwave leakage intensity measured outside the equipment is far below the national standard limit, indicating high safety. This modular design also reduces equipment investment and maintenance costs.

[0040] The terminology and expressions used herein are for descriptive purposes only, and the invention should not be limited to these terms and expressions. The use of these terms and expressions does not imply the exclusion of any illustrative and descriptive equivalents (or parts thereof), and it should be recognized that various modifications that may exist should also be included within the scope of the claims. Other modifications, variations, and substitutions may also exist. Accordingly, the claims should be considered to cover all such equivalents.

[0041] Similarly, it should be noted that although the present invention has been described with reference to the specific embodiments described above, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and various equivalent changes or substitutions can be made without departing from the spirit of the present invention. Therefore, any changes or modifications to the above embodiments within the scope of the essential spirit of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A microwave heating system for a precision temperature-controlled reactor, characterized in that, include: A microwave power radiator includes at least two antenna units arranged around the reactor for radiating microwave energy into the reactor. The multiplexed feed network has multiple independent branches, each branch connecting to one of the antenna elements, and each branch is configured to exhibit low-loss transmission characteristics for different preset center frequencies, so as to selectively direct energy to the corresponding independent branch and the antenna element according to the frequency of the input microwave. A controllable power source is connected to the input of the multiplexer network to generate microwave energy with adjustable frequency and power. A stirrer, installed inside the reactor, is used to stir the materials; A temperature sensor is used to monitor the temperature of the materials inside the reactor. The controllable power source is configured to: based on the feedback signal from the temperature sensor and a preset temperature curve, adjust the frequency of the output microwave, and utilize the energy directional distribution function of the multiplexer network based on frequency selection characteristics to feed microwave energy into the independent branch and the antenna unit corresponding to the frequency, thereby selectively activating the antenna units in different spatial orientations of the reactor, and controlling the heating intensity by adjusting the power of the output microwave, so as to achieve zoned closed-loop heating of the materials in the reactor.

2. The microwave heating system for a precision temperature-controlled reactor according to claim 1, characterized in that, The antenna unit is an air-substrate patch antenna, which includes a patch antenna structure printed on a metal radiating surface, and an air dielectric layer is formed between the metal radiating surface and the ground plane.

3. The microwave heating system for a precision temperature-controlled reactor according to claim 1, characterized in that... The isolation between the independent branches of the multiplexed power supply network shall not be less than 20dB.

4. The microwave heating system for a precision temperature-controlled reactor according to claim 1, characterized in that, The controllable power source is further configured to run a PID control algorithm, which dynamically adjusts the output power to make the heating rate of the material controllable within the range of 0-20℃ / min, and to ensure that the temperature error during the constant temperature stage does not exceed ±4℃.

5. The microwave heating system for a precision temperature-controlled reactor according to claim 1, characterized in that, The controllable power source is further configured to: when the temperature sensor detects that the temperature difference between different areas inside the reactor exceeds 10°C, adjust the radiation intensity of the antenna unit in the corresponding area by switching the output frequency.

6. The microwave heating system for a precision temperature-controlled reactor according to claim 1, characterized in that, It also includes a microwave shield and a microwave leakage detector. When the detected microwave leakage exceeds 0.4 W / m², the controllable power source is configured to cut off the microwave energy output.

7. The microwave heating system for a precision temperature-controlled reactor according to claim 1, characterized in that, The reactor is made of quartz glass or special ceramics, and the antenna unit is fixed by an adjustable mounting bracket. The distance between the radiating surface of the antenna unit and the outer wall of the reactor is adjusted to within the range of 8-12 cm.

8. The microwave heating system for a precision temperature-controlled reactor according to claim 1, characterized in that, The stirrer is a magnetic stirrer with an adjustable speed of 50-200 r / min.

9. A microwave heating method using the system described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Parameter preset, input process parameters including multiple custom temperature profiles; S2: Zoned heating control, based on a preset curve and real-time feedback from the temperature sensor, dynamically adjusts the frequency and power of the output microwave through the controllable power source; wherein, by switching the output frequency, microwave energy is selectively directed to different antenna units via the multiplexer network to achieve differentiated heating of different sectors within the reactor. S3: Homogenization process. During the heating process, the stirrer is activated to stir the material. Combined with the zoned heating control in step S2, the temperature of the material in the reactor rises uniformly and follows the preset curve.

10. The microwave heating method according to claim 9, characterized in that, In step S2, the controllable power source uses a time-slice polling or temperature deviation-driven strategy to determine the timing and order of switching the output frequency to activate different antenna elements.

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