Microwave transmission structure capable of bearing pressure

Abstract

The invention provides a microwave transmission structure capable of bearing pressure, and belongs to the technical field of microwave energy application. The coaxial synthesis output structure is used for reducing the acting sectional area of gas pressure and comprises a solid-state microwave generating source; a withstand voltage synthesizer; two ends of the coaxial transmission line are respectively connected with the output end of the solid-state microwave generation source and the input end of the withstand voltage synthesizer; the input end of the voltage-withstanding waveguide is connected with the output end of the voltage-withstanding synthesizer; and one side of the voltage-withstanding wave-transparent window is connected with the voltage-withstanding synthesizer through the voltage-withstanding waveguide, and the other side of the voltage-withstanding wave-transparent window is connected with The coaxial synthesis output structure is innovatively introduced, the gas pressure acting sectional area can be remarkably reduced, and therefore the total gas pressure borne by the microwave device is greatly reduced; and meanwhile, the waveguide of the high-pressure gas flowing area is subjected to pressure-bearing strengthening design, so that the reliable bearing capacity for high-pressure gas leakage and medium residues when the wave-transparent pressure-resistant structure fails is endowed, and safe and efficient transmission of microwaves in a large-pressure-difference environment is realized.

Description

Technical Field

[0001] This invention relates to the field of microwave energy application technology, and in particular to a pressure-bearing microwave transmission structure. Background Technology

[0002] Microwaves refer to electromagnetic waves with frequencies between 300MHz and 300GHz. Their heating technology, characterized by rapid heating, fast thermal response, and low energy consumption, has found widespread application in modern production and daily life. Pressure environments can provide effective pressure to catalyze specific chemical reactions; therefore, microwave heating technology under pressure conditions is of significant value in fields such as composite material curing and microwave chemical catalysis. Achieving efficient microwave energy transfer under large pressure differentials is a prerequisite for the development of high-pressure microwave heating technology.

[0003] In existing technologies, microwave transmission structures under differential pressure environments generally employ a scheme of directly sealing the pressure-bearing components (as shown in Chinese patents CN201410471231.0 and CN202778415U), relying on a microwave-transparent pressure-bearing medium to achieve microwave transmission and pressure sealing. However, under the action of high-power microwaves, the internal electric field distribution of the medium is complex, which can easily lead to structural failure due to local overheating, resulting in reduced equipment safety. Furthermore, the pressure and microwave power bearing capacity is limited, making large-scale application difficult. To address this issue, the applicant previously proposed a "pressure relief-sealing" coordinated microwave transmission scheme (Chinese patent CN118156755A), which decouples the gas path and microwave channel through an I-shaped structure, playing a positive role in ensuring the safety of personnel and equipment. However, the existence of a pressure relief path cannot, in principle, prevent the escape of medium residues, and the increased structural complexity restricts the improvement of transmission efficiency.

[0004] Therefore, there is an urgent need for a transmission structure that can achieve safe and efficient microwave transmission under large pressure difference environments. Summary of the Invention

[0005] In view of this, in order to solve the technical problems of low safety and transmission efficiency of existing microwave power feeding structures under differential pressure, and to improve structural safety, system power feeding efficiency and pressure bearing capacity, this invention provides a pressure-bearing microwave transmission structure. Based on the essential mechanism of gas pressure generation, and through systematic theoretical analysis, simulation and experimental verification, a coaxial synthetic output structure is innovatively introduced, which can significantly reduce the cross-sectional area of ​​gas pressure action, thereby greatly reducing the total gas pressure borne by microwave devices. At the same time, by implementing pressure-bearing reinforcement design on the waveguide in the high-pressure gas flow area, the transmission structure is endowed with reliable bearing capacity for high-pressure gas leakage and dielectric residue when the wave-transmitting pressure-resistant structure fails, ultimately achieving safe and efficient microwave transmission under large differential pressure environments.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A pressure-resistant microwave transmission structure includes a coaxial synthesized output structure for reducing the cross-sectional area affected by gas pressure, the coaxial synthesized output structure comprising:

[0008] Solid-state microwave generator;

[0009] Pressure-resistant synthesizer;

[0010] A coaxial transmission line, with its two ends connected to the output end of the solid-state microwave generator and the input end of the voltage-resistant synthesizer, respectively.

[0011] A voltage-resistant waveguide, the input of which is connected to the output of the voltage-resistant synthesizer;

[0012] The pressure-resistant waveguide is connected to the pressure-resistant synthesizer on one side via the pressure-resistant waveguide, and connected to the working environment on the other side.

[0013] Preferably, the wall thickness t, the circumscribed circle diameter l, the tensile strength limit σ of the constituent materials of the pressure-resistant waveguide are related to the maximum design pressure difference ΔP across the pressure-resistant waveguide window. max Must meet:

[0014]

[0015] Preferably, the coaxial line at the microwave input terminal of the pressure-resistant synthesizer is composed of inner and outer conductors and a dielectric layer between the inner and outer conductors; wherein, the maximum pressure difference ΔP max Radii a and b of the inner and outer conductors, and maximum transmission power Q. max The following relationship should be satisfied:

[0016] 1.95×10 -10 ΔP max ≥π(b 2 -a 2 )≥0.8×10 -7 Q max .

[0017] Preferably, when there is more than one solid-state microwave generator, the maximum phase difference of the output signals of each solid-state microwave generator at the same time is... Should meet

[0018] Preferably, when there is more than one solid-state microwave generator, the maximum frequency difference Δf between the output signals of each solid-state microwave generator at the same time should satisfy Δf max ≤0.01f.

[0019] Preferably, the wave-transparent pressure-resistant window is made of a material with a dielectric constant of less than 20 and a dielectric loss of less than 0.25.

[0020] The pressure-bearing microwave transmission structure provided by this invention, based on the fundamental mechanism of gas pressure generation, and through systematic theoretical analysis, simulation, and experimental verification, innovatively introduces a coaxial synthesized output structure. This significantly reduces the cross-sectional area affected by gas pressure, thereby substantially reducing the total gas pressure borne by the microwave device. Simultaneously, by implementing pressure-bearing reinforcement design on the waveguide in the high-pressure gas flow area, the transmission structure is endowed with reliable bearing capacity against high-pressure gas leakage and dielectric residue in the event of failure of the wave-transmitting pressure-resistant structure. Ultimately, this achieves safe and efficient microwave transmission under large pressure difference environments. Compared to existing technologies, it has the following beneficial effects:

[0021] (1) By using a pressure-resistant synthesizer to achieve coaxial synthesis output of multiple solid-state microwave sources, this design can significantly reduce the cross-sectional area of ​​the structure and improve the reliability of the pressure sealing system.

[0022] (2) The microwave transmission structure of the present invention can effectively block high-pressure gas and medium residue when the microwave-transparent pressure-resistant window fails, thus ensuring the safety of equipment and personnel.

[0023] (3) This microwave transmission structure can significantly improve the power carrying capacity and pressure resistance of the high-voltage microwave heating system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a typical pressure-bearing microwave transmission structure according to the present invention.

[0025] Figure 2 This is a schematic diagram of a pressure-bearing microwave transmission structure specifically used in an embodiment of the present invention.

[0026] Figure 3 This is the water pressure testing device used in this invention, where the left figure is the device design diagram and the right figure is the field test situation.

[0027] Figure 4 These are on-site photos of the hydrostatic test conducted in this invention, where (a), (b), (c), and (d) show the changes in holding pressure at different stages, respectively.

[0028] Figure 5 This invention provides an internal stress analysis of waveguide structures with different wall thicknesses. The left figure shows the stress distribution of a 10mm wall thickness waveguide, and the right figure shows the stress distribution of a 20mm wall thickness waveguide.

[0029] Figure 6 This is a typical design process for a wave-transparent pressure-resistant window according to the present invention, wherein (a) is a schematic diagram of the wave-transparent pressure-resistant window structure, (b) shows the influence of the structural parameters of the wave-transparent pressure-resistant window on the microwave transmittance of the structure, and (c) shows the influence of the structural parameters of the wave-transparent pressure-resistant window on the microwave reflectance of the structure.

[0030] In the figure, 1 is a pressure-resistant transparent window; 2 is a pressure-resistant waveguide; 3 is a pressure-resistant synthesizer; 4 is a coaxial transmission line; and 5 is a solid-state microwave generator. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] In the description of this invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] like Figure 1 As shown, the present invention provides a pressure-resistant microwave transmission structure, including a coaxial synthesized output structure for reducing the cross-sectional area affected by gas pressure, the coaxial synthesized output structure comprising:

[0035] Solid-state microwave generator 5 is used to excite microwaves.

[0036] The withstand voltage synthesizer 3 is used to synthesize the microwaves generated by the multi-channel solid-state microwave generator 5 into a single-channel output microwave signal to improve the power level of the system.

[0037] A coaxial transmission line 4 connects to the output of the solid-state microwave generator 5 and the input of the voltage-resistant synthesizer 3 at its two ends, respectively. The voltage-resistant synthesizer 3 has at least one coaxial connector. The voltage-resistant synthesizer 3 is tightly connected to the coaxial transmission line 4 via the coaxial connector, ensuring stable microwave signal transmission. This effectively disperses pressure and improves the overall pressure resistance of the structure. Simultaneously, the tight integration of the voltage-resistant waveguide and the voltage-resistant transparent window further enhances the reliability and safety of microwave transmission.

[0038] A pressure-resistant waveguide 2 has its input end connected to the output end of the pressure-resistant synthesizer 3. A pressure-resistant transparent window has its output end tightly connected to the output end of the pressure-resistant waveguide 2 to ensure lossless transmission of microwave signals. The overall structure is compact, optimizes pressure distribution, and improves system stability and service life.

[0039] The pressure-resistant waveguide window 1 is connected to the pressure-resistant synthesizer 3 on one side via the pressure-resistant waveguide 2, and connected to the working environment on the other side. The pressure-resistant waveguide window 1 is preferably made of a material with a dielectric constant of less than 20 and a dielectric loss of less than 0.25. The design of the pressure-resistant waveguide window 1 not only ensures the transmission efficiency of microwave signals but also significantly improves the pressure resistance of the structure. Its material selection balances wave transmission performance and mechanical strength, ensuring stable signal transmission even under high-pressure environments. Through optimized design, the overall structure achieves uniform pressure distribution, further extending the service life of the equipment and enhancing the reliability and safety of the system.

[0040] The pressure-resistant transparent window 1, pressure-resistant waveguide 2, pressure-resistant synthesizer 3, coaxial transmission line 4, and solid-state microwave generator 5 are coaxially arranged to form a coaxial synthesized output structure, which can significantly reduce the cross-sectional area of ​​gas pressure action, thereby greatly reducing the total gas pressure borne by microwave devices.

[0041] In this invention, the wall thickness t, the circumscribed circle diameter l, the tensile strength limit σ of the constituent materials of the pressure-resistant waveguide 2, and the maximum designed pressure difference ΔP between the two sides of the pressure-resistant waveguide window are all considered. max Must meet:

[0042] The design of the pressure-resistant waveguide 2 must ensure stable microwave transmission even under high-voltage conditions. Simultaneously, the material selection and structural design of the pressure-resistant waveguide window must comprehensively consider dielectric properties and mechanical strength to ensure its reliability and long-term stability under extreme conditions. By optimizing these parameters, this invention enables efficient and safe microwave transmission, suitable for various complex environments.

[0043] In this invention, the coaxial line at the microwave input end of the pressure-resistant synthesizer 3 is composed of inner and outer conductors and a dielectric layer between the inner and outer conductors; wherein, the maximum pressure difference ΔP max Radii a and b of the inner and outer conductors, and maximum transmission power Q. max The following relationship should be satisfied:

[0044] 1.95×10 -10 ΔP max ≥π(b 2 -a 2 )≥0.8×10 -7 Q maxThe selection of materials for the inner and outer conductors must balance conductivity and mechanical strength, while the dielectric layer must possess low loss and high insulation properties to ensure the stability and safety of microwave transmission under high power and high voltage environments.

[0045] In this invention, when the number of solid-state microwave generators 5 is more than one, the maximum phase difference of the output signals of each solid-state microwave generator at the same moment is... Should meet Each solid-state microwave generator is precisely phase-controlled to ensure phase consistency of the synthesized microwave signal, thereby improving overall output power and transmission efficiency. The design of the withstand voltage synthesizer 3 further optimizes the microwave signal synthesis process, reduces energy loss, and enhances the reliability and stability of the system.

[0046] In this invention, when there is more than one solid-state microwave generator 5, the maximum frequency difference Δf between the output signals of each solid-state microwave generator at the same time should satisfy Δf. max ≤0.01f. By strictly limiting the frequency difference, the synchronization of the output signals of each source is ensured, further improving the purity and stability of the synthesized microwave, avoiding power loss caused by frequency detuning, and enhancing the overall performance and reliability of the system under high load.

[0047] like Figure 2 As shown, the technical solution of the present invention will be clearly and thoroughly described with reference to specific embodiments, as follows:

[0048] A typical pressure-bearing microwave transmission structure suitable for feeding 6kW-level 2.44-2.45GHz high-power microwaves from an atmospheric pressure environment into a 1.6MPa high-pressure tank. The structure, configured sequentially from low-pressure to high-pressure end, consists of: six continuously adjustable 1kW solid-state microwave generators 5 operating in the 2.44-2.45GHz frequency band, connected to a pressure-resistant synthesizer 3 via six coaxial microwave transmission lines 4; the other end of the pressure-resistant synthesizer 3 is connected to a 6kW-level microwave circulator and a water load, and transmits microwave energy to the high-pressure environment through a pressure-resistant waveguide 2 and a wave-transparent pressure-resistant window 1; the ends of the transmission lines are connected to a conventional waveguide and a radiating antenna. Based on this framework, the wall thickness design of the pressure-resistant waveguide and the pressure-resistant synthesizer 3 was first carried out. The inventor's team, through extensive preliminary simulation analysis and experimental research, constructed the following... Figure 3 The pressure-resistant waveguide 2 and pressure-resistant synthesizer 3 shown in the hydrostatic testing apparatus systematically tested the pressure-bearing performance of the waveguide under different wall thicknesses and cross-sectional dimensions. It was found that the waveguide's pressure resistance 2 is directly proportional to the waveguide thickness and the tensile strength limit of the material, and inversely proportional to the hollow cross-sectional dimensions. Taking the BJ22 waveguide as an example, when using 11mm thick aluminum alloy, the waveguide showed significant deformation after a five-hour hydrostatic test; when the aluminum alloy thickness increased to 12mm, the waveguide did not show significant deformation. Based on this, the inventors further conducted a series of hydrostatic tests on waveguides of different materials and sizes. Figure 4The design formula for the wall thickness of the withstand waveguide 2 is derived. Analogous to the research method of pressure-resistant waveguide 2, the inventors also conducted hydrostatic tests on the dimensions of the coaxial connector to calibrate the compressive strength limit parameters of coaxial structures of different sizes, 1.95×10 -10 ΔP max ≥π(b 2 -a 2 Establish an empirical formula. Based on this, conduct microwave power experiments, taking the constraint that microwave power does not cause significant heating of the coaxial line, and establish the empirical relationship between coaxial dimensions and microwave power: π(b 2 -a 2 )≥0.8×10 -7 Q max .

[0049] In this embodiment, the maximum pressure difference ΔP max =1.6 MPa, the maximum cross-sectional area geometric dimension is the diagonal of the hollow cross-section of the selected BJ22 waveguide. The line length is specified, and the tensile strength of the 7075 aluminum alloy used is 524 MPa. Calculations show that the wall thickness of the pressure-resistant waveguide 2 should be no less than 11.175 mm. Considering both cost and process feasibility, this example determines the wall thickness of the pressure-resistant waveguide to be 20 mm. To verify the design effectiveness, the inventors used ANSYS finite element software to simulate the surface stress distribution of the 20 mm and 10 mm wall thickness pressure-resistant waveguides under a 1.6 MPa gas pressure impact. Figure 5 The results show that the maximum principal stress on the surface of the 10mm waveguide reaches 560MPa, exceeding the tensile strength limit of the material; while the maximum principal stress on the surface of the 20mm waveguide is only 166MPa, far below the tensile strength limit of the material, confirming the rationality of the design.

[0050] In addition, a specific design was carried out for the coaxial connector dimensions of the pressure-resistant synthesizer 3. Polytetrafluoroethylene (PTFE) was selected as the medium filling material, and the preliminary dimensional design was based on the following empirical formula:

[0051] 1.95×10 -10 ΔP max ≥π(b 2 -a 2 )≥0.8×10 -7 Q max

[0052] Calculation yields (b) 2 -a 2 It must meet the requirement of ≥5.09mm. 2 And ≤49.68mm 2 Based on market standard cable specifications, the final design parameters are a = 1.25mm and b = 4.25mm.

[0053] The wave-transparent, pressure-resistant window 1 is made of quartz glass with a dielectric constant of 3.77 and a dielectric loss of 0.001. Firstly, HFSS simulation software was used to optimize the dimensions of the quartz glass. Figure 6 The focus was on controlling the ratio of the glass cross-sectional area to the pressure-resistant waveguide cross-section and the thickness parameters. The simulation optimization objective was to maximize microwave transmittance and minimize insertion loss and reflectivity at the 2.45 GHz frequency. When the area ratio was 1.35 and the glass thickness was 25 mm, the microwave transmittance of the high-voltage end transparent pressure-resistant window reached 99.48%, and the insertion loss was 0.41%.

[0054] In practical microwave transmission, frequency, power, and phase detection elements (such as detectors and phase detectors) can be integrated into the microwave source and synthesizer to ensure that the output frequency, power, and phase of each solid-state source are highly consistent before starting the synthesized output, thereby achieving maximum output efficiency. Specifically, to ensure output power and waveform stability, the maximum frequency error Δf between each solid-state microwave source is controlled. max The working center frequency f must satisfy Δf max ≤0.01f. Maximum phase difference of the output microwave signal. Must meet The maximum error ΔQ of the output power value Q max ΔQ must be satisfied max ≤0.1Q.

[0055] The above description is merely a preferred embodiment of the present invention. However, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. A pressure-bearing microwave transmission structure, characterized in that, Includes a coaxial synthesis output structure for reducing the cross-sectional area of ​​the gas pressure action, the coaxial synthesis output structure comprising: Solid-state microwave generator; Pressure-resistant synthesizer; A coaxial transmission line, with its two ends connected to the output end of the solid-state microwave generator and the input end of the voltage-resistant synthesizer, respectively. A voltage-resistant waveguide, the input of which is connected to the output of the voltage-resistant synthesizer; The pressure-resistant waveguide is connected to the pressure-resistant synthesizer on one side via the pressure-resistant waveguide, and connected to the working environment on the other side.

2. The pressure-bearing microwave transmission structure according to claim 1, characterized in that, The wall thickness t, circumscribed circle diameter l, tensile strength limit σ of the constituent materials of the pressure-resistant waveguide, and the maximum design pressure difference ΔP between the two sides of the pressure-resistant waveguide are described. max Must meet:

3. The pressure-bearing microwave transmission structure according to claim 1, characterized in that, The coaxial line at the microwave input terminal of the voltage synthesizer consists of inner and outer conductors and a dielectric layer between them; wherein, the maximum pressure difference ΔP max Radii a and b of the inner and outer conductors, and maximum transmission power Q. max The following relationship should be satisfied: 1.95×10 -10 ΔP max ≥π(b 2 -a 2 )≥0.8×10 -7 Q max 。 4. The pressure-bearing microwave transmission structure according to claim 1, characterized in that, When there is more than one solid-state microwave generator, the maximum phase difference of the output signals of each solid-state microwave generator at the same moment is... Should meet 5. The pressure-bearing microwave transmission structure according to claim 1, characterized in that, When there is more than one solid-state microwave generator, the maximum frequency difference Δf between the output signals of each solid-state microwave generator at the same time should satisfy Δf max ≤0.01f.

6. The pressure-bearing microwave transmission structure according to claim 1, characterized in that, The wave-transparent pressure-resistant window is made of a material with a dielectric constant of less than 20 and a dielectric loss of less than 0.25.

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