Microwave heating equipment, waste gas treatment system, waste gas treatment method and microwave heating device

Abstract

The invention relates to the technical field of microwave heating, and discloses microwave heating equipment, a waste gas treatment system, a waste gas treatment method and a microwave heating device.The microwave heating equipment comprises a container body (1) with a heating cavity (11) and the microwave heating device (3) installed on the side wall of the container body; heated carriers (2) which are oppositely arranged at intervals are arranged in the heating cavity, the microwave heating device comprises a medium radiator (33) extending into the heating cavity, the medium radiator is provided with a radiation section (331), and a pair of radiation surfaces (331a) facing the corresponding heated carriers and a pair of side surfaces (331b) perpendicular to the radiation surfaces are formed on the radiation section. The pair of radiation surfaces and the pair of side surfaces respectively extend close to each other in a direction towards the interior of the heating cavity, so that the radiation section has a tapered tapered structure. The microwave heating equipment can effectively improve the uniformity of microwave heating of a large-scale heated carrier and the microwave incidence efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave heating, and in particular to a microwave heating device, a waste gas treatment system, a waste gas treatment method and a microwave heating apparatus. Background Art

[0002] The deep treatment and near-zero emission of volatile organic compounds (VOCs) are increasingly receiving attention from society. Compared with the recovery method VOCs treatment technology, the destruction method VOCs treatment technology can completely and once-for-all convert VOCs into CO2 and H2O, and can also convert methane into CO2, thus achieving the complete incineration of small molecule hydrocarbons, which has irreplaceable advantages. After the dual carbon goals were proposed, the VOCs destruction treatment technology that relies on natural gas incineration does not meet the original intention of the dual carbon goals and the coordinated reduction of VOCs emissions. Therefore, efficient, green and low-carbon destruction method VOCs treatment technology has become the main development trend.

[0003] Catalytic oxidation technology relies on electric heaters for heating and waste heat exchangers to recover excess heat to heat the catalyst bed, achieving lower temperature destruction and treatment of VOCs, which itself has the huge advantage of energy saving and consumption reduction. However, due to the instability of inlet concentration, severe heat loss, and delayed heating response, there is still a huge room for improvement in the utilization of thermal energy in catalytic oxidation technology, and microwave catalytic oxidation technology has emerged. Microwave catalytic oxidation technology has the huge advantages of fast heating response speed, overall heating, high heating efficiency, and energy saving and consumption reduction. However, at this stage, microwave catalytic oxidation technology is still in the small-scale test stage, and there are huge difficulties in scaling up the process equipment. This is mainly because large-scale microwave catalytic reactors are difficult to design, and there is a lack of efficient and safe microwave radiators that can achieve uniform and safe dispersion of electromagnetic waves in the reactor, thereby uniformly and safely achieving overall rapid heating of the catalyst bed.

[0004] High-power magnetrons and the matching high-power microwave power supplies are expensive, and a single high-power microwave oven is difficult to achieve uniform heating of large-scale reactors.

[0005] Microwaves can propagate in a certain direction in the waveguide in the form of alternating electric and magnetic fields. After being absorbed by dielectric loss materials, the electromagnetic energy is converted into heat energy, thereby heating the bed. However, as the size of the heated bed increases, it is difficult for microwaves to achieve uniform heating of large-scale beds, and even cause local overheating of the heated material, thus affecting the overall utilization efficiency and safety of the bed.

[0006] Microwaves are injected into the heating cavity or reactor through the waveguide. There are absorbing materials in the heating cavity to absorb microwaves. Microwaves that are not absorbed by the materials will inevitably return through the waveguide, thus affecting the energy utilization rate. The higher the microwave injection efficiency, the higher its energy utilization rate.

[0007] The use of an efficient radiator can effectively improve the radiation uniformity of microwaves in a large-scale bed. However, most radiators are metal-leakage waveguides, with currents on the metal surface and high electric field intensities at the gap leakage points, even higher than the breakdown electric field intensity under humid air conditions, posing certain safety hazards for the treatment of flammable and explosive VOCs. Summary of the Invention

[0008] The object of the present invention is to improve the uniformity of microwave heating of a large-scale catalyst bed, the microwave incident efficiency, and the safety of the dielectric radiator, and to provide a microwave heating device, an exhaust gas treatment system, an exhaust gas treatment method, and a microwave heating apparatus.

[0009] To achieve the above object, on the one hand, the present invention provides a microwave heating device, comprising:

[0010] A container main body forming at least one heating cavity, in which heat-absorbing carriers with wave-absorbing ability are arranged at intervals and oppositely along a first direction;

[0011] A microwave heating device installed on the side wall of the container main body, the microwave heating device comprising a microwave generating unit, a dielectric radiator extending through the side wall of the container main body into the heating cavity, and a waveguide for guiding the microwave generated by the microwave generating unit to the dielectric radiator. The dielectric radiator has a radiation section located in the heating cavity, and the radiation section forms a pair of radiation surfaces respectively facing the corresponding heat-absorbing carriers and a pair of side surfaces perpendicular to the radiation surfaces. Along the direction towards the inside of the heating cavity, the pair of radiation surfaces and the pair of side surfaces respectively extend close to each other, so that the radiation section has a tapered structure with a gradually decreasing cross-section.

[0012] Preferably, a plurality of the heating cavities separated by a first microwave shielding element and distributed in sequence along the first direction are formed in the container main body, and the microwave heating devices are respectively installed at positions corresponding to the respective heating cavities.

[0013] Preferably, at least part of the heating cavities are provided with a second microwave shielding element, which divides the heating cavity into a plurality of sub-heating cavities distributed in sequence perpendicular to the first direction, and the microwave heating devices are respectively installed at positions corresponding to the respective sub-heating cavities.

[0014] Preferably, along a direction perpendicular to the first direction, the container main body has a rectangular cross-section, and a plurality of the microwave heating devices arranged along a second direction perpendicular to the first direction are respectively installed on the opposite side walls of the container main body. The dielectric radiators of the respective microwave heating devices respectively extend through the side wall of the container main body into the heating cavity along a third direction perpendicular to the first direction and the second direction.

[0015] Preferably, a plurality of the heating cavities separated by the first microwave shielding element and sequentially distributed along the first direction are formed in the container body, and the microwave heating devices are respectively installed at positions corresponding to the respective heating cavities, and the microwave heating devices provided corresponding to adjacent heating cavities are installed on the same or adjacent side walls of the container body.

[0016] Preferably, a catalyst is provided in the heat carrier, and a reactant inlet and a product outlet are provided on the container body to allow a fluid reactant introduced from the reactant inlet to flow through the heat carrier along the first direction or the third direction and be discharged through the product outlet.

[0017] Preferably, the length of the heating cavity in the first direction is 2 to 4 times the extension length of the radiation section in the third direction.

[0018] Preferably, the microwave generating unit is a magnetron disposed in the explosion-proof excitation cavity, the explosion-proof excitation cavity and the waveguide are physically isolated by a dielectric sealing window, and the microwave generated by the magnetron can enter the waveguide through the dielectric sealing window.

[0019] Preferably, the dielectric radiator further has a coupling section extending in the waveguide and a transmission section connected between the coupling section and the radiation section, the transmission section passes through the side wall of the container body and has a flange portion mounted to fit the outer wall surface of the container body.

[0020] Preferably, the length of the coupling section is 0.75 to 1 times the microwave wavelength; the length of the radiation section is more than 0.8 times the microwave wavelength, preferably 0.8 to 2.5 times the microwave wavelength.

[0021] Preferably, along a direction perpendicular to the extending direction of the dielectric radiator, the radiation section has a rectangular cross-section, and the width of the radiation surface is greater than the width of the side surface, and / or, along the direction towards the transmission section, the cross-sectional area of the coupling section increases.

[0022] Preferably, the dielectric constant of the material of the dielectric radiator is greater than 9, and the dielectric loss < 0.02.

[0023] Preferably, the material of the dielectric radiator is ceramic.

[0024] A second aspect of the present invention provides an exhaust gas treatment system, and the exhaust gas treatment system includes the above-mentioned microwave heating device.

[0025] The third aspect of the present invention provides a method for treating waste gas, characterized in that the method for treating waste gas includes the step of introducing the waste gas containing volatile organic compounds into the above-mentioned microwave heating device for treatment, wherein the waste gas containing volatile organic compounds flows through the heat-receiving carrier so as to be heated to the reaction temperature by the microwave heating device.

[0026] The fourth aspect of the present invention provides a microwave heating device, including a microwave generating unit, a dielectric radiator for radiating the microwave generated by the microwave generating unit to a heat-receiving medium, and a waveguide for guiding the microwave generated by the microwave generating unit to the dielectric radiator. The dielectric radiator includes a radiation section having a rectangular cross-section, and a pair of radiation surfaces for facing the heat-receiving medium and a pair of side surfaces perpendicular to the radiation surfaces are formed in the radiation section. Along the conduction direction of the microwave, the pair of radiation surfaces and the pair of side surfaces extend close to each other, so that the radiation section has a tapered structure with a gradually decreasing cross-section.

[0027] Preferably, the microwave generating unit is a magnetron disposed in an explosion-proof excitation cavity. The explosion-proof excitation cavity and the waveguide are physically isolated by a dielectric sealing window, and the microwave generated by the magnetron can penetrate through the dielectric sealing window and enter the waveguide.

[0028] Preferably, the dielectric radiator further has a coupling section extending in the waveguide and a transmission section connected between the coupling section and the radiation section. The transmission section has a flange portion.

[0029] Preferably, along the conduction direction of the microwave, the length of the coupling section is 0.75-1 times the wavelength of the microwave; the length of the radiation section is more than 0.8 times the wavelength of the microwave, preferably 0.8-2.5 times the wavelength of the microwave.

[0030] Preferably, the coupling section has a rectangular cross-section. Along the direction towards the transmission section, the cross-sectional area of the coupling section increases, and / or the width of the radiation surface is greater than the width of the side surface.

[0031] Preferably, the dielectric constant of the material of the dielectric radiator is greater than 9, and the dielectric loss <0.02.

[0032] Preferably, the material of the dielectric radiator is ceramic.

[0033] Through the above technical solutions, the microwave heating device and the waste gas treatment system of the present invention can utilize microwave to achieve more uniform heating of the bed layer on a larger scale. The distribution uniformity of the microwave in the heating cavity (also called the reaction cavity or free space) is better, and the uniformity of the bed layer heating is higher. Further, by arranging a plurality of microwave heating devices in the reaction cavity, multi-port microwave radiation is realized, reducing the power of the microwave power supply and the magnetron, thereby reducing the equipment cost.

[0034] In the microwave heating equipment and microwave heating device of the present invention, microwaves are transmitted to the dielectric radiator through the explosion-proof excitation cavity and waveguide. The dielectric radiator absorbs and transfers the microwaves, and then evenly radiates them into the reaction cavity. The dielectric radiator itself has no current and does not generate heat, and is intrinsically safe when in contact with flammable and explosive gases; the incident efficiency of the dielectric radiator is high (high utilization rate of microwave energy), and the microwave reflection power can be further adjusted by pins to reduce the reflection power; the magnetron is arranged in the explosion-proof excitation cavity, and the explosion-proof excitation cavity is isolated from the outside air respectively, and is physically isolated from the waveguide through a dielectric sealing window; the waveguide is also isolated from the reaction cavity through the dielectric radiator, so as to realize a sealed explosion-proof excitation cavity and a sealed waveguide, and the radiation is safer.

[0035] In addition, the uniformity of microwave distribution and the microwave incident efficiency in the large-scale heating cavity can be further adjusted by adjusting the lengths of the coupling section, transmission section and radiation section of the dielectric radiator and the taper angle, etc., so as to realize the free design of reaction cavities of different scales.

[0036] In short, using the microwave heating device of the present invention to heat a large-scale catalyst bed has the beneficial effects of intrinsic safety, high utilization rate of microwave energy, uniform microwave radiation, uniform heating of the bed, and relatively low cost.

[0037] Compared with the prior art, the technical solution of the present invention has more advantages in large-scale heating, can realize the heating of a larger-scale catalyst bed, and is convenient for realizing a large-scale microwave reaction device; moreover, the heating is safer, the maximum electric field strength in the reactor is much smaller than the electric field breakdown strength in humid air, and there is no current on the surface of the radiator; furthermore, the technical solution of the present invention can be used in flammable and explosive places, especially when dealing with flammable and explosive gases, the intrinsic safety design is realized both inside and outside the reactor; in addition, by adding a dielectric radiator, the overall heating of the microwave in the catalyst bed can be made more uniform, avoiding local high temperature, resulting in safety problems or reducing the service life of the catalyst.

[0038] The technical solution of the present invention can be applied to the microwave heating of large-scale solids, such as heating microwave-absorbing catalysts or microwave-absorbing adsorbents and other microwave-absorbing solids to realize the rapid heating of the microwave-absorbing solids; heating the microwave-absorbing catalyst to participate in chemical reactions of gases or liquids to realize the efficient and rapid heating of the catalyst; heating the microwave-absorbing adsorbent for the environmental protection treatment field of thermal desorption of the adsorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic cross-sectional structure view of a microwave heating equipment according to a preferred embodiment of the present invention;

[0040] Figure 2 is Figure 1Front view of the dielectric radiator of the microwave heating device used in the medium microwave heating equipment;

[0041] Figure 3 is Figure 2 Different projection views of the dielectric radiator;

[0042] Figure 4 Front view of a variant embodiment of the dielectric radiator of the present invention;

[0043] Figure 5 Schematic structural diagram of a microwave heating equipment according to another preferred embodiment of the present invention;

[0044] Figure 6 shows Figure 5 Cross-sectional view of the layout scheme of multiple microwave heating devices in the medium microwave heating equipment;

[0045] Figure 7 shows Figure 5 Top view of the layout scheme of multiple microwave heating devices in the medium microwave heating equipment;

[0046] Figure 8 Schematic structural diagram of a microwave heating equipment according to another preferred embodiment of the present invention;

[0047] Figure 9 shows Figure 8 Cross-sectional view of the layout scheme of multiple microwave heating devices in the medium microwave heating equipment;

[0048] Figure 10 shows Figure 8 Top view of the layout scheme of multiple microwave heating devices in the medium microwave heating equipment;

[0049] Figure 11 Schematic structural diagram of a microwave heating equipment according to another preferred embodiment of the present invention;

[0050] Figure 12 Schematic structural diagram of a microwave heating equipment according to another preferred embodiment of the present invention;

[0051] Figure 13 Surface temperature distribution diagram of heating implemented by a microwave heating device without a dielectric radiator;

[0052] Figure 14 Surface temperature distribution diagram of heating implemented by a microwave heating equipment with multiple dielectric radiators but without a first microwave shielding element;

[0053] Figure 15 Surface temperature distribution diagram of heating implemented by a microwave heating equipment with multiple dielectric radiators and provided with a first microwave shielding element;

[0054] Figure 16 It is a surface temperature distribution diagram obtained by heating with a microwave heating device that uses multiple dielectric radiators and is provided with a first microwave shielding element and a second microwave shielding element;

[0055] Figure 17 It is a temperature distribution diagram obtained by heating with a microwave heating device in which microwave heating devices corresponding to adjacent heating cavities are installed on the same side wall;

[0056] Figure 18 It is a temperature distribution diagram obtained by heating with a microwave heating device in which microwave heating devices corresponding to adjacent heating cavities are installed on adjacent side walls;

[0057] Figure 19 It shows the contour map of the electric field distribution of Example 6;

[0058] Figure 20 It shows the contour map of the electric field distribution of Example 7;

[0059] Figure 21 It shows the contour map of the electric field distribution of Example 8;

[0060] Figure 22 It shows the contour map of the electric field distribution of Example 9;

[0061] Figure 23 It shows the contour map of the electric field distribution of Example 10;

[0062] Figure 24 It shows the contour map of the electric field distribution of Example 11;

[0063] Figure 25 It shows the contour map of the electric field distribution of Example 12;

[0064] Figure 26 It shows the contour map of the electric field distribution of Example 13.

[0065] Description of Reference Numerals

[0066] 1 - Container body; 11 - Heating cavity; 12 - Reactant inlet; 13 - Product outlet; 14 - First microwave shielding element; 15 - Second microwave shielding element;

[0067] 2 - Heat - receiving carrier;

[0068] 3 - Microwave heating device; 31 - Microwave generating unit; 32 - Waveguide; 32a - Pin; 33 - Dielectric radiator; 331 - Radiation section; 331a - Radiation surface; 331b - Side surface; 34 - Explosion - proof excitation cavity; 332 - Transmission section; 332a - Flange portion; 333 - Coupling section; 35 - Dielectric sealing window. Detailed Description of the Invention

[0069] The following is a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not used to limit the present invention.

[0070] In the description of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating relative importance or implicitly indicating the quantity of the indicated technical features. Thus, unless otherwise specified, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features; the meaning of "a plurality" is two or more. The term "comprising" and any deformation thereof means non-exclusive inclusion, and there may be or be added one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0071] In addition, the terms indicating the orientation or positional relationship such as "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are described based on the orientation or relative positional relationship shown in the drawings, and are only for the convenience of describing the present application in a simplified manner, rather than indicating that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present application.

[0072] In addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, or it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0073] A dielectric antenna is an antenna that uses a microwave dielectric material as a radiation unit. According to the radiation principle, it can be divided into two categories: dielectric rod antennas and dielectric resonator antennas. Among them, the dielectric rod antenna is a rod-shaped antenna made of a low-loss high-frequency dielectric material and belongs to a typical traveling-wave antenna.

[0074] The dielectric rod can guide the propagation of electromagnetic waves. Compared with a metal waveguide, its guiding effect is not perfect, and there will be a considerable amount of power overflow at the dielectric boundary and radiate into free space (such as a reaction cavity). It is precisely due to this radiation characteristic that the design of the dielectric rod antenna becomes possible. The dielectric rod antenna is generally fed by a waveguide, has a simple structure and a low profile.

[0075] The tapered dielectric rod antenna is an axially radiating surface wave antenna. The tapered dielectric rod antenna is characterized by a tapered structure, which can achieve good impedance matching between the dielectric rod antenna and air, reduce surface wave reflection, and improve radiation efficiency. The surface wave from the feeding system is transmitted in the dielectric with no or very little reflection. The cross-section of the dielectric waveguide decreases linearly, so the phase velocity of the electromagnetic wave transmitted along the waveguide gradually increases. When it reaches the tip of the dielectric rod, the phase velocity reaches or approaches the speed of light, and at this time, the electromagnetic wave changes from a bound wave to a free space wave and radiates into the free space.

[0076] Referring to Figure 1 As shown, a microwave heating device according to a preferred embodiment of the present invention includes a container body 1 and a microwave heating device 3 mounted on the side wall of the container body 1. The container body 1 defines at least one heating cavity 11, and heat-absorbing carriers 2 with wave-absorbing ability are arranged in the heating cavity 11 at intervals and oppositely along a first direction (the vertical direction shown in the figure). The microwave heating device 3 is arranged to be able to emit microwaves into the heating cavity 11 (especially to the heat-absorbing carriers 2) to heat the polar media in the heat-absorbing carriers 2. In order to enable each part of the heat-absorbing carriers 2 to uniformly receive microwave radiation, usually, microwave heating devices 3 identical to each other can be respectively installed at both ends (the left and right ends shown in the figure) of the heating cavity 11. For example, when the container body 1 is formed to have a rectangular cross-section (such as Figure 7 , Figure 10 shown), the microwave heating devices 3 corresponding to the same heating cavity 11 can be installed in pairs on the opposite side walls of the container body 1; when the container body 1 is formed to have a circular cross-section, two microwave heating devices 3 corresponding to the same heating cavity 11 can be installed on the peripheral wall of the container body 1 and are located on the same straight line opposite to each other.

[0077] Each microwave heating device 3 respectively includes a microwave generating unit 31, a dielectric radiator 33 extending through the side wall of the container body 1 into the heating cavity 11, and a waveguide 32 for guiding the microwaves generated by the microwave generating unit 31 to the dielectric radiator 33. Among them, the dielectric radiator 33 is arranged as a tapered dielectric rod antenna to improve radiation efficiency.

[0078] Specifically, as Figures 2 - 4 shown, the dielectric radiator 33 adopted by the present invention may include a coupling section 333, a transmission section 332, and a radiation section 331. Among them, the coupling section 333 and the radiation section 331 are respectively arranged on opposite sides of the transmission section 332, and both the coupling section 333 and the radiation section 331 can be formed as frustum pyramids.

[0079] Accordingly, the dielectric radiator 33 is integrally formed into a structure that is thin at both ends and thick in the middle. In the coupling section 333 and the radiation section 331, all four side surfaces are trapezoidal, and the two end surfaces are rectangular. In a preferred case, the widths of the upper and lower side surfaces of the coupling section 333 and the radiation section 331 are greater than the widths of the front and rear side surfaces. Among them, the radiation section 331 is located in the heating cavity 11 and is formed with a pair of radiation surfaces 331a respectively facing the corresponding heat-receiving carrier 2 and a pair of side surfaces 331b perpendicular to the radiation surface 331a. The width of the radiation surface 331a can be greater than the width of the side surface 331b. And along the direction towards the inside of the heating cavity 11, the pair of radiation surfaces 331a extend close to each other, and the pair of side surfaces 331b also extend close to each other, so that the radiation section 331 has a tapered structure. Through this setting, the microwave generated by the microwave generating unit 31 can be uniformly radiated into the heating cavity 11 by the radiation section 331, especially efficiently and uniformly radiated to the heat-receiving carrier 2 facing it by the radiation surface 331a, so that the polar medium of the heat-receiving carrier 2 can be uniformly heated within a large scale range.

[0080] In the dielectric radiator 33, the length of the coupling section 333 is preferably 0.75 - 1 times the microwave wavelength; the length of the radiation section 331 is preferably more than 0.8 times the microwave wavelength, and more preferably 0.8 - 2.5 times the microwave wavelength. The microwave can be 2450 MHz or 915 MHz microwave. When the microwave is 2450 MHz microwave, the microwave wavelength is about 122.4 mm.

[0081] In the dielectric radiator 33, the taper angle of the coupling section 333 is preferably 5 - 85°, and the taper angle of the radiation section 331 is preferably 5 - 85°.

[0082] In the present invention, preferably, the dielectric constant of the material of the dielectric radiator is greater than 9, and the dielectric loss < 0.02. Further preferably, the material of the dielectric radiator is ceramic.

[0083] According to an embodiment of the present invention, as Figure 4 shown, the transmission section 332 of the dielectric radiator 33 can have a flange portion 332a. In the state of being installed on the container body 1, the transmission section 332 passes through the side wall of the container body 1, and the flange portion 332 is attached to the outer wall surface of the container body 1, and the flange portion can be tightly fixed to the side wall of the reaction cavity 6 through a waveguide flange.

[0084] Furthermore, the microwave heating device 3 according to the present invention may include an explosion-proof excitation cavity 34. The microwave generating unit 31 may be a magnetron disposed in the explosion-proof excitation cavity 2. One end of the explosion-proof excitation cavity 34 is connected to the waveguide 32, and the other end is provided with the dielectric radiator 33 described above. The coupling section 333 of the dielectric radiator 33 extends into the waveguide 32.

[0085] In a preferred embodiment, the explosion-proof excitation cavity 34 and the waveguide 32 are physically isolated by a dielectric sealing window 35, and the microwave generated by the magnetron can pass through the dielectric sealing window 35 and enter the waveguide 32. In a specific embodiment, the dielectric sealing window 35 is a sealed quartz window.

[0086] In a preferred embodiment, the waveguide may further be provided with pins 32a, and the microwave reflection power can be adjusted through the pins 32a, so as to further adjust and reduce the reflection power.

[0087] According to the microwave heating device of the present invention, the output power of the magnetron is adjusted by a microwave power supply, so as to adjust the body temperature of the wave-absorbing carrier (such as a wave-absorbing catalyst). Through the dielectric radiator, the overall heating, uniform heating and safe heating of a large-scale catalyst bed can be uniformly realized, so that the microwave generation, propagation and radiation are in a safe operating state.

[0088] According to the microwave heating device of the present invention, the magnetron generates microwaves of a certain frequency when connected to an external high-voltage power supply. The microwaves are transmitted into the waveguide 32 through the explosion-proof excitation cavity 34. At the same time, the explosion-proof excitation cavity 34 and the waveguide 32 are physically isolated by a dielectric sealing window 35. The dielectric sealing window 35 is generally made of a wave-transmitting material, and its main function is to transmit microwaves while generating physical isolation. The coupling section 333 and at least part of the transmission section 332 of the dielectric radiator 33 are located in the waveguide 32, and the radiation section 331 is located in the free space (heating cavity 11). The upper and lower sides of the free space are heat-absorbing carriers (such as a catalyst bed) with good wave-absorbing and heat-conducting properties. The magnetron generates microwaves, which are transmitted through the waveguide 32. The dielectric radiator 33 further couples, transmits and radiates directionally and uniformly, and finally the carrier absorbs the microwave energy, achieving the ultimate goal of heating the carrier. After the carrier reaches the predetermined temperature, the injected reaction medium passes through the carrier and reacts efficiently with the assistance of the carrier, realizing the final reaction process.

[0089] In the microwave heating device, the magnetron is fixed in the explosion-proof excitation cavity 34. At the same time, the power supply line, grounding wire, and cooling pipeline required by the magnetron are connected to the external microwave power supply and cooling medium through the explosion-proof excitation cavity 34. The other end of the waveguide 32 is hermetically connected to the side wall of the container body 1, further realizing the airtight isolation between the reactor and the waveguide 32, and the physical isolation between the excitation cavity and the waveguide, and between the waveguide and the external space. The above settings are conducive to preventing flammable and explosive gases in the free space from entering the waveguide and the magnetron, or preventing flammable and explosive gases in the external environment from entering the excitation cavity, thereby realizing the physical explosion-proof design of the whole machine.

[0090] Figures 5 - 12 The microwave heating equipment of different preferred embodiments is shown, in which a plurality of microwave heating devices are arranged on the side wall of the container body 1 in different ways. Among them, the radiation section 331 of the dielectric radiator 33 in the microwave heating device extends into the reaction cavity 11. In a specific embodiment, the microwave heating device is connected to the side wall of the container body 1 through the transmission section 332 of the dielectric radiator 33, and the connection can be realized by means of bolts or the like.

[0091] In the microwave heating reaction system, preferably, the length of the heating cavity 11 in the first direction is 2-4 times the length of the radiation section 331 extending into the heating cavity 11.

[0092] In the case of being applied to the waste gas treatment system, a catalyst can be provided in the heat carrier 11 in the heating cavity 11 to be able to heat the catalyst for reacting the waste gas flowing through the catalyst.

[0093] In the microwave heating equipment of the present invention, wave-absorbing materials (i.e., heat carriers), such as wave-absorbing catalysts or wave-absorbing adsorbents, are arranged opposite to each other in the heating cavity 6, and the intermediate space is used to place the dielectric radiator 33. The external power supply and the cooling medium enter the explosion-proof excitation cavity and are connected to the magnetron. The magnetron generates microwaves and delivers them to the explosion-proof excitation cavity, the waveguide, and then into the dielectric radiator. The microwave energy is coupled by the coupling section of the dielectric radiator, further transmitted by the transmission section, and gradually released by the radiation section. The microwaves are absorbed by the wave-absorbing catalyst or other wave-absorbing materials, thereby generating electromagnetic loss and further converting it into heat energy.

[0094] In the microwave heating equipment, the radiation surface 331a of the radiation section 33 faces the heat carrier 11.

[0095] In the microwave heating reaction system, preferably, multiple heating cavities 11 are provided in the container body 1, and two layers of heat-receiving carriers 11 facing each other are respectively arranged in each heating cavity 11. Microwave heating devices 3 are respectively arranged in pairs on the opposite sides of the space formed between the two heat-receiving carriers 11 on both sides. Further preferably, a reactant inlet 12 and a product outlet 13 may be provided on the container body 1 to allow the fluid reactant introduced through the reactant inlet 12 to flow through the heat-receiving carrier 2 in the first direction and be discharged through the product outlet 13. The reaction fluid entering the container body 1 passes through multiple heat-receiving carriers in sequence from bottom to top (the first direction) for treatment. In a more preferred embodiment, in two adjacent spaces up and down, the microwave heating devices arranged therein are vertically staggered. According to this preferred embodiment, the heat-receiving carrier can be heated more uniformly.

[0096] In a further preferred embodiment, in order to further improve the uniformity of carrier heating, multiple heating cavities 11 separated by the first microwave shielding element 14 and arranged in sequence in the first direction may be formed in the container body 1, and microwave heating devices 3 are respectively installed at positions corresponding to each heating cavity 11 (please refer to Figure 5 、 Figure 6 and Figure 9 ). And / or, a second microwave shielding element 15 may be provided in at least part of the heating cavities 11. The second microwave shielding element 15 divides the heating cavity 11 into multiple sub-heating cavities arranged in sequence perpendicular to the first direction, and microwave heating devices 3 are respectively installed at positions corresponding to each sub-heating cavity (please refer to Figure 11 ). In a specific embodiment, the first microwave shielding element 14 and the second microwave shielding element 15 are metal partitions, for example, they may be stainless steel plates.

[0097] According to an embodiment of the present invention, Figures 5 - 7 shows an arrangement scheme of multiple microwave heating devices in a microwave heating device. Among them, multiple heating cavities 11 arranged in the first direction are provided in the container body 1, and heat-receiving carriers 2 arranged at intervals and facing each other in the first direction are respectively provided in each heating cavity 11. Multiple microwave heating devices 3 corresponding to each heating cavity 11 are installed on the side walls of the container body 1. Along a direction perpendicular to the first direction, the container body 1 has a rectangular cross-section, and multiple microwave heating devices 3 arranged in the second direction ( Figure 7 the up and down direction in Figure 6 and Figure 7extends into the heating cavity 11 through the side wall of the container body 1 in the left - right direction (in the left - right direction in the figure). According to this embodiment, each space constitutes a plurality of different reaction modules connected in series with each other. Each reaction module controls the heating temperature through its own medium radiator, and the temperature of each reaction bed layer is monitored in real time by setting a temperature transmitter in the reaction bed layer and fed back to the microwave power supply. The microwave power supply outputs a control signal of a certain magnitude to the magnetron, so that the output power of the magnetron can be controlled. Among them, the microwave heating devices 3 corresponding to adjacent heating cavities 11 are installed on the same side wall of the container body 1.

[0098] According to another embodiment of the present invention, Figures 8 - 10 shows the layout scheme of multiple microwave heating devices in a microwave heating device according to another preferred embodiment of the present invention. Among them, multiple layers of heating cavities 11 distributed in the first direction are provided in the container body 1. Heat - receiving carriers 2 arranged at intervals and opposite to each other in the first direction are respectively provided in each heating cavity 11. A plurality of microwave heating devices 3 corresponding to each heating cavity 11 are installed on the side wall of the container body 1. Along a direction perpendicular to the first direction, the container body 1 has a rectangular cross - section, and a plurality of microwave heating devices 3 arranged in a second direction ( Figure 10 the up - down direction and the left - right direction in the figure) are respectively installed on the opposite side walls of the container body 1. The medium radiators 33 of each microwave heating device 3 respectively extend into the heating cavity 11 through the side wall of the container body 1 in a third direction ( Figure 10 the left - right direction and the up - down direction in the figure). Different from Figures 5 to 7 the embodiment, in this preferred embodiment, the microwave heating devices 3 corresponding to adjacent heating cavities 11 are installed on adjacent side walls of the container body 1.

[0099] According to another embodiment of the present invention, Figure 11 shows that the microwave heating devices of the microwave heating device are staggered and distributed, and the inner cavity of the container body 1 is divided into heating cavities 11 each including a plurality of sub - heating cavities by the first microwave shielding element 14 and the second microwave shielding element 15. Among them, multiple layers of heating cavities 11 distributed in the first direction are provided in the container body 1. Heat - receiving carriers 2 arranged at intervals and opposite to each other in the first direction are respectively provided in each heating cavity 11. A plurality of microwave heating devices 3 corresponding to each heating cavity 11 are installed on the side wall of the container body 1. The multiple layers of heating cavities 11 are separated by the first microwave shielding element 14, and each heating cavity 11 is divided into a plurality of sub - heating cavities distributed in sequence in a direction perpendicular to the first direction by the second microwave shielding element 15, and microwave heating devices 3 are respectively installed at positions corresponding to each sub - heating cavity. According to this embodiment, the heating uniformity of the bed layer or the uniformity of the microwave distribution can be further improved, and the maximum field strength of the electric field can be reduced.

[0100] According to another embodiment of the present invention, as Figure 12 shown, a plurality of heating cavities 11 are distributed along a first direction (the left - right direction in the figure). A plurality of microwave heating devices 3 corresponding to each heating cavity 11 are installed on the side wall of the container body 1. The dielectric radiator 33 of the microwave heating device 3 extends into the heating cavity 11 along a third direction (the up - down direction in the figure) perpendicular to the first direction. The container body 1 is provided with a reactant inlet 12 and a product outlet 13 to allow the fluid reactant introduced through the reactant inlet 12 to flow through the heat - receiving carrier 2 along the third direction and be discharged through the product outlet 13.

[0101] The substance flowing through the heat - receiving medium can be at least one of gas, liquid or solid.

[0102] The present invention also provides an exhaust gas treatment system, an exhaust gas treatment method including the above - mentioned microwave heating equipment, and a microwave heating device applicable to the above - mentioned microwave heating equipment. Among them, the exhaust gas treatment method includes injecting the exhaust gas containing volatile organic compounds (VOCs) into the container body of the microwave heating equipment described above for treatment. During the treatment process, the heat - receiving carrier arranged in the reaction cavity is heated by the microwave heating device. The heat - receiving carrier is selected as an absorbing catalyst, also known as a catalyst bed. According to the exhaust gas treatment method of the present invention, VOCs and the like enter the catalyst bed, and under the action of the hot catalyst bed, VOCs are converted into CO2 and H2O and heat is released. According to the exhaust gas treatment method of the present invention, there is no current on the surface of the dielectric radiator, and the heating is safer; moreover, the catalyst bed is uniformly heated, and local high temperatures can be avoided.

[0103] The present invention will be further described below through examples.

[0104] Comparative Example 1

[0105] As Figure 13 shown, in the absence of a dielectric radiator, only heated by an 8 - port waveguide, the microwave incident radiation efficiency is 94.94%, the maximum temperature difference of the catalyst bed is 350°C, and the temperature difference is large. And the temperature is mainly concentrated at the microwave radiation breach, and it is difficult to achieve uniform heating radiation far from the microwave feed port.

[0106] Example 1

[0107] As Figure 14 shown, in the presence of a dielectric radiator, it can be seen that the uniformity of the catalyst bed is significantly improved. The catalyst bed far from the microwave feed port is heated with good results, the microwave incident efficiency is increased to 96.11%, and the maximum temperature difference is reduced to 180°C. However, the temperature on both sides of the middle range far from the microwave feed port is high and the temperature in the middle is slightly lower.

[0108] Example 2

[0109] As Figure 15 shown, on the premise of having a dielectric radiator and the presence of a first microwave shielding element, the uniformity of the catalyst bed is significantly improved again, and the maximum temperature difference is reduced to 180 °C. The incident efficiency is increased to 99.11. Although the maximum temperature difference is not significantly reduced, the temperature uniformity of most of the catalyst bed far from the microwave feed port is significantly improved.

[0110] Example 3

[0111] As Figure 16 shown, in the case of having a dielectric radiator and the presence of a first microwave shielding element and a second microwave shielding element, the uniformity of the catalyst bed is further significantly improved, and the maximum temperature difference is reduced to 30 °C.

[0112] Example 4

[0113] As Figure 17 shown, the same-direction radiation scheme is adopted for the radiators at different upper and lower levels. The maximum temperature difference of the middle catalyst bed is 60 °C.

[0114] Example 5

[0115] As Figure 18 shown, the radiation scheme with an intersection of 90° is adopted for the radiators at different upper and lower levels. The maximum temperature difference of the middle catalyst bed is 52 °C.

[0116] Thus, in the microwave heating reaction system, both the heating method with multiple radiators arranged in multiple layers in parallel and the heating method with multiple radiators arranged in multiple layers staggered with each other can obtain a good uniform heating effect; moreover, by setting metal partitions between multiple groups of radiators, the radiation efficiency and heating uniformity can be further improved.

[0117] Examples 6 - 9

[0118] Define el1 as the coupling section length, el2 as the radiation section length, and el3 as the transmission section length. Under the premise of simultaneous radiation irradiation by 8 microwave magnetrons of 1 kW and a single bed size of 700 mm × 700 mm, when the individual radiation cavities of two opposite dielectric radiators are 175 mm, the electric field strengths and incident efficiencies corresponding to different el1 / el2 / el3 are shown in Table 1 below.

[0119] Table 1

[0120]

[0121]

[0122] In Examples 6-9, the maximum electric field strength in the reactor does not exceed 3.87×10 3 v / m, which is much smaller than the electric field breakdown strength under humid air.

[0123] The electric field distribution nephograms of Examples 6-9 are respectively as Figures 19 - 22 shown. In the figure, whether the electric field strength represented by each is uniform represents whether the temperature of the catalyst bed heated is uniform. It can be seen from the figure that the electric field strength in Examples 6 and 7 is mainly concentrated near the reactor wall, indicating that the electric field strength distribution is uneven, the temperature distribution of the catalyst bed is uneven, and at the same time the microwave energy utilization rate is also relatively low; in Examples 8 and 9, the electric field is relatively more uniform, representing that the temperature of the heated catalyst bed is more uniform, and the incident efficiency is also relatively high. Within a certain range, the lengths of the radiators represented by Examples 8 and 9 are more conducive to generating a uniform and efficient heating effect.

[0124] Examples 10-13

[0125] Except for the adjustments made to the coupling section length, radiation section length, and transmission section length, the other conditions are the same as those in Examples 6-9. The corresponding electric field strengths and incident efficiencies for different el1 / el2 / el3 are shown in Table 2 below.

[0126] Table 2

[0127]

[0128] The electric field distribution nephograms of Examples 10-13 are respectively as Figures 23 - 26 shown. It can be seen from the figure that when the coupling section lengths are the same or similar and are within a reasonable range, the utilization efficiency of the dielectric radiator is relatively high, all exceeding 95%. When the radiation section length is relatively short (such as in Examples 10 and 11), the microwave distribution in the reactor is uneven; when the lead-in radiation section is within a reasonable range value, there will be a better microwave electric field distribution effect and radiation efficiency.

[0129] It can be seen from the above Examples 6-13 that by adjusting the coupling section length, transmission section length, and radiation section length, the distribution operation of the electric field can be further adjusted, and thus the heating uniformity of the bed layer and the radiation efficiency can be adjusted.

[0130] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A microwave heating device, characterized in that, Comprising: A container body (1) formed with at least one heating cavity (11), in which heat-absorbing carriers (2) with wave-absorbing ability are arranged oppositely at intervals along a first direction; A microwave heating device (3) installed on the side wall of the container body (1), the microwave heating device (3) includes a microwave generating unit (31), a dielectric radiator (33) extending through the side wall of the container body (1) into the heating cavity (11), and a waveguide (32) for guiding the microwave generated by the microwave generating unit (31) to the dielectric radiator (33). The dielectric radiator (33) has a radiation section (331) located in the heating cavity (11), and the radiation section (331) is formed with a pair of radiation surfaces (331a) respectively facing the corresponding heat-absorbing carriers (2) and a pair of side surfaces (331b) perpendicular to the radiation surfaces (331a). Along the direction towards the inside of the heating cavity (11), the pair of radiation surfaces (331a) and the pair of side surfaces (331b) extend close to each other respectively, so that the radiation section (331) has a tapered structure.

2. The microwave heating device according to claim 1, characterized in that, A plurality of the heating cavities (11) separated by a first microwave shielding element (14) and distributed in sequence along the first direction are formed in the container body (1), and the microwave heating devices (3) are respectively installed at positions corresponding to the respective heating cavities (11).

3. The microwave heating device according to claim 1, wherein, A second microwave shielding element (15) is provided in at least part of the heating cavity (11), and the second microwave shielding element (15) divides the heating cavity (11) into a plurality of sub-heating cavities distributed in sequence perpendicular to the first direction, and the microwave heating devices (3) are respectively installed at positions corresponding to the respective sub-heating cavities.

4. The microwave heating device according to claim 1, characterized in that, Along a direction perpendicular to the first direction, the container body (1) has a rectangular cross-section, and a plurality of the microwave heating devices (3) arranged along a second direction perpendicular to the first direction are respectively installed on the opposite side walls of the container body (1). The dielectric radiators (33) of the respective microwave heating devices (3) respectively extend through the side wall of the container body (1) into the heating cavity (11) along a third direction perpendicular to the first direction and the second direction.

5. The microwave heating device according to claim 4, characterized in that, A plurality of the heating cavities (11) separated by a first microwave shielding element (14) and distributed in sequence along the first direction are formed in the container body (1), and the microwave heating devices (3) are respectively installed at positions corresponding to the respective heating cavities (11). The microwave heating devices (3) provided corresponding to adjacent heating cavities (11) are installed on the same or adjacent side walls of the container body (1).

6. The microwave heating device according to claim 4, characterized in that, A catalyst is provided in the heat-absorbing carrier (2), and a reactant inlet (12) and a product outlet (13) are provided on the container body (1) to allow the fluid reactant introduced from the reactant inlet (12) to flow through the heat-absorbing carrier (2) along the first direction or the third direction and be discharged through the product outlet (13).

7. The microwave heating device according to claim 4, characterized in that, The length of the heating cavity (11) in the first direction is 2-4 times the extension length of the radiation section (331) in the third direction.

8. The microwave heating device according to claim 1, characterized in that The microwave generating unit (31) is a magnetron disposed in the explosion-proof excitation cavity (34). The explosion-proof excitation cavity (34) is physically isolated from the waveguide (32) by a dielectric sealing window (35), and the microwave generated by the magnetron can enter the waveguide (32) through the dielectric sealing window (35).

9. The microwave heating device according to claim 1, characterized in that, The dielectric radiator (33) further has a coupling section (333) extending in the waveguide (32) and a transmission section (332) connected between the coupling section (333) and the radiation section (331). The transmission section (332) passes through the side wall of the container body (1) and has a flange portion (332a) mounted to fit against the outer wall surface of the container body (1).

10. The microwave heating device according to claim 8, characterized in that, The length of the coupling section (333) is 0.75-1 times the microwave wavelength; the length of the radiation section (331) is more than 0.8 times the microwave wavelength, preferably 0.8-2.5 times the microwave wavelength.

11. The microwave heating device according to claim 8, wherein, Along a direction perpendicular to the insertion direction of the dielectric radiator (33), the radiation section (331) has a rectangular cross-section, and the width of the radiation surface (331a) is greater than the width of the side surface (331b), and / or, along the direction towards the transmission section (332), the cross-sectional area of the coupling section (333) increases.

12. The microwave heating device according to claim 1, characterized in that, The dielectric constant of the material of the dielectric radiator (33) is greater than 9, and the dielectric loss < 0.02; Preferably, the material of the dielectric radiator (33) is ceramic.

13. An exhaust gas treatment system, characterized in that, This waste gas treatment system includes the microwave heating device according to any one of claims 1-12.

14. A waste gas treatment method, characterized in that, This waste gas treatment method includes introducing the waste gas containing volatile organic compounds into The step of treating in the microwave heating device according to any one of claims 1-12, wherein the waste gas containing volatile organic compounds flows through the heat-receiving carrier (2) to be heated to the reaction temperature by the microwave heating device (3).

15. A microwave heating device, characterized in that, It includes a microwave generating unit (31), a dielectric radiator (33) for radiating the microwave generated by the microwave generating unit (31) to the heat-receiving medium, and a waveguide (32) for guiding the microwave generated by the microwave generating unit (31) to the dielectric radiator (33). The dielectric radiator (33) includes a radiation section (331) having a rectangular cross-section, and a pair of radiation surfaces (331a) for facing the heat-receiving medium and a pair of side surfaces (331b) perpendicular to the radiation surface (331a) are formed in the radiation section (331). Along the conduction direction of the microwave, the pair of radiation surfaces (331a) and the pair of side surfaces (331b) extend close to each other, so that the radiation section (331) has a tapered structure.

16. The microwave heating device according to claim 15, characterized in that, The microwave generating unit (31) is a magnetron disposed in the explosion-proof excitation cavity (34). The explosion-proof excitation cavity (34) is physically isolated from the waveguide (32) by a dielectric sealing window (35), and the microwave generated by the magnetron can pass through the dielectric sealing window (35) and enter the waveguide (32).

17. The microwave heating device according to claim 15, characterized in that, The dielectric radiator (33) further has a coupling section (333) extending in the waveguide (32) and a transmission section (332) connected between the coupling section (333) and the radiation section (331). The transmission section (332) has a flange portion (332a).

18. The microwave heating device according to claim 17, wherein Along the conduction direction of the microwave, the length of the coupling section (333) is 0.75 - 1 times the microwave wavelength; the length of the radiation section (331) is more than 0.8 times the microwave wavelength, preferably 0.8 - 2.5 times the microwave wavelength.

19. The microwave heating device according to claim 17, wherein The coupling section (333) has a rectangular cross-section. Along the direction towards the transmission section (332), the cross-sectional area of the coupling section (333) increases, and / or the width of the radiation surface (331a) is greater than the width of the side surface (331b).

20. The microwave heating device according to claim 15, wherein, The dielectric constant of the material of the dielectric radiator (33) is greater than 9, and the dielectric loss < 0.02; Preferably, the material of the dielectric radiator (33) is ceramic.

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