Flame synthesis apparatus and method

Abstract

The application provides a flame synthesis device, comprising a mixing cavity, a precursor pipeline, a first pipeline and a second pipeline, a chamber of the mixing cavity forms a mixing output in a first direction of the mixing cavity; the precursor pipeline further has a precursor channel, the precursor channel forms a precursor receiving port at a receiving end and an output port communicated with the mixing chamber at an output end; the first pipeline and the second pipeline both have channels, the output ends are connected with the mixing cavity, the channels form receiving ports at the receiving ends and output ports at the output ends, and the output ports are communicated with the mixing chamber; the extension directions of the first pipeline and the second pipeline have an included angle with the first direction; an inner wall of the first channel is tangent to an inner wall of the mixing cavity, and the extension direction of the second channel is towards an axis of the precursor channel. The application further provides a flame synthesis method executed by using the flame synthesis device. The flame synthesis device and method in the application have a lower risk of tempering.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, specifically to a flame synthesis apparatus and method. Background Technology

[0002] Flame synthesis is a technique for preparing nanomaterials, offering advantages for continuous industrial production. Some techniques propose introducing gaseous precursors into laminar premixed stagnant flame technology. Premixed fuel, oxidant, and gaseous precursor are ejected from the burner outlet and form a flame below a low-temperature stagnant plate. The gaseous precursor undergoes rapid heating at the flame front, followed by rapid cooling due to contact with the stagnant plate, resulting in a highly active material with uniform particle size, good crystallinity, and locked metastable state on the stagnant plate surface.

[0003] However, existing gas-phase precursors have significant gaps in elemental coverage, typically limiting their use to synthesizing single-component materials such as titanium dioxide and gallium oxide, thus restricting their application in synthesizing complex multi-component nanomaterials. While liquid-phase precursors offer significant advantages in elemental coverage, laminar premixed stagnant flame technology is currently only applicable to gas-phase precursors; liquid-phase precursors have not yet been successfully applied in this technology. One of the challenges lies in the difficulty of achieving uniform mixing of liquid-phase precursors with fuel and oxidizers in flame synthesis devices suitable for gas-phase precursors. Furthermore, uneven precursor distribution can lead to drastic changes in localized combustion rates, significantly increasing the risk of backfire, thus hindering the application of liquid-phase precursors in this technology. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a flame synthesis apparatus that can improve the uniformity of mixing and reduce the risk of backfire.

[0005] The present invention also proposes a flame synthesis method using the above-described flame synthesis apparatus.

[0006] A flame synthesis apparatus according to a first aspect of the present invention includes: A mixing chamber having a mixing cavity forming a mixing outlet in a first direction of the mixing chamber; The precursor pipeline includes a precursor receiving end and a precursor output end, and also has a precursor channel. The precursor output end is connected to the side of the mixing chamber opposite to the first direction. The precursor channel forms a precursor receiving port at the precursor receiving end and a precursor output port at the precursor output end. The precursor receiving port is used to introduce liquid-phase precursor aerosol, and the precursor output port is connected to the mixing chamber. The first conduit includes a first receiving end and a first output end, and also has a first channel. The first output end is connected to the mixing cavity. The first channel forms a first receiving port at the first receiving end and a first output port at the first output end. The first output port is connected to the mixing chamber. The second conduit includes a second receiving end and a second output end, and also has a second channel. The second output end is connected to the mixing cavity. The second channel forms a second receiving port at the second receiving end and a second output port at the second output end. The second output port is connected to the mixing chamber. Wherein, one of the first receiving port and the second receiving port is used to introduce fuel, and the other is used to introduce oxidant; the extension direction of the first pipe and the extension direction of the second pipe are both at an angle to the first direction; the inner wall of the first channel is tangent to the inner wall of the mixing chamber, and the extension direction of the second channel is toward the axis of the precursor channel.

[0007] The flame synthesis apparatus according to embodiments of the present invention has at least the following beneficial effects: Because the inner wall of the first pipe is tangent to the inner wall of the mixing chamber, the gas entering the mixing chamber from the first pipe can flow along the inner wall of the mixing chamber. Furthermore, because the extension direction of the first pipe forms an angle with the first direction, the airflow flowing along the inner wall of the mixing chamber can further form a swirling flow around the axis of the precursor pipe. In a direction perpendicular to the first direction, the portion of the swirling flow near the inner side of the precursor pipe mixes with the liquid-phase precursor aerosol. Since the extension direction of the second pipe is towards the axis of the precursor pipe, the gas entering the mixing chamber from the second pipe, after mixing with the swirling flow, can bring the swirling flow even closer to the axis of the precursor pipe. This allows the fuel and oxidant introduced from the first and second pipes to further mix with the liquid-phase precursor aerosol, improving the uniformity of the mixed gas flow exiting the mixing outlet along the radial direction of the mixing outlet and reducing the risk of flashback during flame synthesis.

[0008] According to some embodiments of the present invention, the flame synthesis apparatus includes a plurality of first pipes and a plurality of second pipes, the plurality of first pipes and the plurality of second pipes being arranged circumferentially along the precursor pipes.

[0009] According to some embodiments of the present invention, a plurality of first pipes and a plurality of second pipes are arranged alternately along the circumference of the precursor pipes.

[0010] According to some embodiments of the present invention, the flame synthesis apparatus includes an even number of first pipes and an even number of second pipes, each of the first pipes being centrally symmetrical about the axis of the precursor pipe, and each of the second pipes being centrally symmetrical about the axis of the precursor pipe.

[0011] According to some embodiments of the present invention, the flame synthesis apparatus further includes an outlet pipe, the outlet pipe including an outlet receiving end and an outlet output end, the outlet receiving end being connected to the mixing chamber; The outlet pipe also has an outlet channel extending along the first direction. The outlet channel includes a first conveying section and a second conveying section distributed along the first direction. The inner walls of the first conveying section and the second conveying section are smoothly connected. The first conveying section forms the mixed output port at the outlet receiving end, and the second conveying section forms the outlet output port at the outlet output end. Along the first direction, the diameter of the second conveying section gradually decreases.

[0012] According to some embodiments of the present invention, the flame synthesis apparatus further includes a filter screen disposed within the first conveying section to separate the first conveying section into a first sub-conveying section and a second sub-conveying section arranged along the first direction.

[0013] According to some embodiments of the present invention, the flame synthesis apparatus further includes a honeycomb tube disposed within the second sub-conveying section; The pore size of the honeycomb tube is smaller than that of the filter screen.

[0014] According to some embodiments of the present invention, the inner wall of the mixing chamber is smoothly connected to the inner wall of the outlet pipe; Along the first direction, the cross-sectional area of ​​the mixing chamber gradually decreases, and the first pipe and the second pipe are spaced apart from the outlet pipe in the first direction.

[0015] According to some embodiments of the present invention, the axis of the outlet channel coincides with the axis of the precursor channel.

[0016] According to a second aspect of the present invention, a flame synthesis method is performed using the flame synthesis apparatus described in any of the above embodiments, comprising: Oxidant is continuously introduced from one of the first receiving port and the second receiving port, and fuel is continuously introduced from the other. Liquid precursor aerosol is continuously introduced into the precursor channel from the precursor receiving port, so that the oxidant, the fuel and the liquid precursor aerosol form a mixed gas flow in the mixing chamber. A stagnation plate is provided on the side of the flame synthesis device where the mixing output port is located, and the mixed gas flow from the mixing output port is ignited.

[0017] The flame synthesis method according to embodiments of the present invention has at least the following beneficial effects: When the premixed gas flowing out of the mixing outlet undergoes combustion, the liquid precursor experiences rapid heating at the flame front, followed by rapid cooling due to contact with the stagnation plate, generating nanomaterials on the stagnation plate surface. Since the inner wall of the first pipe is tangent to the inner wall of the mixing chamber, the gas entering the mixing chamber from the first pipe can flow along the inner wall of the mixing chamber. Furthermore, because the extension direction of the first pipe forms an angle with the first direction, the airflow flowing along the inner wall of the mixing chamber can further form a swirling flow around the axis of the precursor pipe. Along a direction perpendicular to the first direction, the portion of the swirling flow near the inner side of the precursor pipe mixes with the liquid precursor aerosol. Furthermore, since the extension direction of the second pipe is towards the axis of the precursor pipe, the gas entering the mixing chamber from the second pipe mixes with the swirling flow, allowing the swirling flow to move closer to the axis of the precursor pipe. This enables the fuel and oxidant introduced from the first and second pipes to mix further with the liquid-phase precursor aerosol, improving the uniformity of the mixed gas flow from the mixing outlet along the radial direction of the mixing outlet. The mixed gas flow is less prone to backfire during combustion, making the laminar premixing flame suppression technology using liquid-phase precursors safer.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is an overall schematic diagram of the flame synthesis apparatus according to an embodiment of the present invention; Figure 2 for Figure 1 Side view of the flame synthesis apparatus; Figure 3 for Figure 2 The cross-sectional view shown in AA; Figure 4 for Figure 2 The cross-sectional view shown in BB; Figure 5 for Figure 1 A schematic diagram showing a stagnation plate installed in the first direction of the flame synthesis device; Figure 6 for Figure 4 A schematic diagram showing the orientation of the second pipeline axis and the first pipeline axis.

[0020] Figure label: Flame synthesis device 10; Mixing chamber 100, mixing chamber 110, mixing output port 120; Precursor pipe 200, precursor receiver 210, precursor output 220, precursor channel 230, precursor receiver port 240, precursor output port 250; First conduit 300, first receiving end 310, first output end 320, first channel 330, first receiving port 340, first output port 350; Second pipe 400, second receiving end 410, second output end 420, second channel 430, second receiving port 440, second output port 450; Outlet pipe 500, outlet receiving end 510, outlet output end 520, outlet channel 530, first conveying section 540, first sub-conveying section 541, second sub-conveying section 542, second conveying section 550, outlet output port 560; Filter size 600; 700 honeycomb tube; Protect pipe 800, protect channel 810, protect receiving port 820, protect output port 830; Stagnation plate 20. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are 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 limiting this invention.

[0023] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0025] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0026] Please refer to Figures 1 to 6 As shown, the present invention proposes a flame synthesis device 10, including a mixing chamber 100, a precursor pipe 200, a first pipe 300, and a second pipe 400.

[0027] Please refer to Figure 3 As shown, the mixing chamber 100 of the present invention has a mixing chamber 110, and the mixing chamber 110 forms a mixing outlet 120 in a first direction of the mixing chamber 100. The precursor conduit 200 of the present invention includes a precursor receiving end 210 and a precursor output end 220, and also has a precursor channel 230. The precursor output end 220 is connected to the side of the mixing chamber 100 opposite to the first direction. The precursor channel 230 forms a precursor receiving port 240 at the precursor receiving end 210 and a precursor output port 250 at the precursor output end 220. The precursor receiving port 240 is used to introduce liquid-phase precursor aerosol, and the precursor output port 250 is connected to the mixing chamber 110. The liquid-phase precursor aerosol introduced from the precursor receiving port 240 of the present invention can enter the mixing chamber 110 along the first direction and flow out from the mixing outlet 120 connected to the mixing chamber 110 under the action of air pressure.

[0028] Please refer to Figure 2 , Figure 4As shown, the flame synthesis apparatus 10 of the present invention further includes a first pipe 300 and a second pipe 400, which are respectively used to introduce fuel and oxidant into the mixing chamber 110. Specifically, the first pipe 300 includes a first receiving end 310 and a first output end 320, and also has a first channel 330. The first output end 320 is connected to the mixing chamber 100. The first channel 330 forms a first receiving port 340 at the first receiving end 310 and a first output port 350 at the first output end 320. The first output port 350 is connected to the mixing chamber 110. The second pipe 400 includes a second receiving end 410 and a second output end 420, and also has a second channel 430. The second output end 420 is connected to the mixing chamber 100. The second channel 430 forms a second receiving port 440 at the second receiving end 410 and a second output port 450 at the second output end 420. The second output port 450 is connected to the mixing chamber 110. When mixing the combustion improver, oxidizer and liquid precursor aerosol, the operator can introduce fuel and oxidizer through the first receiving port 340 and the second receiving port 440 respectively, so that the fuel and oxidizer can enter the mixing chamber 110 through the first channel 330 and the second channel 430 respectively and mix with the liquid precursor aerosol.

[0029] During long-term practice, the inventors discovered that existing solutions for laminar premixed stagnation flame technology are only applicable to gaseous precursors. When using existing burners for laminar premixed stagnation flame technology to synthesize liquid precursor flames, the premixed gas flows out and burns from the burner outlet facing the stagnation plate 20. Because the liquid precursor is unevenly distributed in the direction perpendicular to the gas flow in the gas flow output from the mixing outlet 120, the unevenly distributed liquid precursor absorbs a large amount of heat during the heating and evaporation process. This results in differences in the combustion speed of the gas flow output from the mixing outlet 120 perpendicular to its own flow direction, and the faster-burning part is prone to backfire.

[0030] In view of this, please refer to Figure 3 , Figure 4 As shown, the extension directions of the first pipe 300 and the second pipe 400 of the present invention both form an angle with the first direction. The inner wall of the first channel 330 is tangent to the inner wall of the mixing chamber 100, and the extension direction of the second channel 430 is toward the axis of the precursor channel 230.

[0031] Since the inner wall of the first pipe 300 is tangent to the inner wall of the mixing chamber 110, the gas entering the mixing chamber 110 from the first pipe 300 can flow along the inner wall of the mixing chamber 110. Furthermore, since the extension direction of the first pipe 300 forms an angle with the first direction, the airflow flowing along the inner wall of the mixing chamber 110 has a component of movement perpendicular to the first direction, which can further form a swirling flow around the axis of the precursor pipe 200. Along the direction perpendicular to the first direction, the portion of the swirling flow near the inner side of the precursor pipe 200 mixes with the liquid precursor aerosol. Furthermore, since the extension direction of the second pipe 400 is toward the axis of the precursor pipe 200, the gas entering the mixing chamber 100 from the second pipe 400 and mixing with the swirling flow can bring the swirling flow closer to the axis of the precursor pipe 200. This allows the fuel and oxidant introduced from the first pipe 300 and the second pipe 400 to mix further with the liquid precursor aerosol, improving the uniformity of the mixed gas flow from the mixing outlet 120 along the radial direction of the mixing outlet 120 and reducing the risk of backfire during the flame synthesis process.

[0032] To facilitate understanding by those skilled in the art, the following description, in conjunction with the accompanying drawings, further explains that "the extension direction of the second pipe 400 is toward the axis of the precursor pipe 200." Please refer to... Figure 6 As shown, where Figure 6 The dashed line indicates Figure 4 The flame synthesis apparatus 10 has a projection plane perpendicular to a first direction, with the axis of the second pipe 400 and the axis of the first pipe 300 projected onto the projection plane. The orthographic projection of the axis of the second pipe 400 onto the projection plane is the first projection, and the orthographic projection of the precursor channel 230 onto the projection plane is the second projection. The first projection passes through the second projection, meaning that the extension direction of the second pipe 400 is towards the axis of the precursor channel 200. As a preferred embodiment, in some embodiments, the geometric center of the second projection coincides with the first projection. For example, the second projection is circular, and the center of the second projection coincides with the first projection.

[0033] Without departing from the inventive concept of this invention, those skilled in the art can adjust the shape of the mixing chamber 110. In some embodiments, the shape of the mixing chamber 110 is a convex polygonal prism or frustum extending along a first direction, such as a quadrangular prism, a regular pentagonal prism, or a regular hexagonal prism extending along a first direction, or a quadrangular frustum, a pentagonal frustum, or a hexagonal frustum that narrows along a first direction.

[0034] In some embodiments, the mixing chamber 110 is shaped as a cylinder extending in a first direction or a frustum extending in a first direction.

[0035] Please refer to Figure 3 , Figure 4As shown, in some embodiments, the mixing chamber 110 is a circular channel that tapers along a first direction, and the end of the circular channel in the first direction forms a mixing outlet 120 in the mixing chamber 100. With this design, the airflow can be accelerated by the tapering circular channel as it moves along the first direction, thereby reducing the possibility of backfire.

[0036] Further, please refer to Figure 4 As shown, in some embodiments, the flame synthesis apparatus 10 includes a plurality of first pipes 300 and a plurality of second pipes 400, which are arranged circumferentially along the precursor pipe 200. By providing a plurality of first pipes 300 and a plurality of second pipes 400 arranged circumferentially, the fuel and oxidant entering the mixing chamber 110 from the first pipes 300 and the second pipes 400 can be further dispersed along the circumferential direction of the precursor pipe 200, thereby improving the uniformity of the mixed gas flow and reducing the risk of backfire during the flame synthesis process.

[0037] On the other hand, the flame synthesis device 10 can simultaneously mix more types of fuels and combustion accelerants through multiple first pipes 300 and multiple second pipes 400, thereby adjusting the proportion of each component in the mixed gas flow, which is beneficial for more precise control of the flame synthesis process. Specifically, taking the first pipe 300 as an example, in some embodiments, the flame synthesis device 10 includes at least two first pipes 300, one of which has a first receiving port 340 for introducing air, and the other has a first receiving port 340 for introducing oxygen.

[0038] Further, please refer to Figure 4 As shown, in some embodiments, multiple first pipes 300 and multiple second pipes 400 are arranged alternately along the circumference of the precursor pipe 200. Through this arrangement, the gas entering the mixing chamber 110 from each of the first pipes 300 forms a cyclone in the mixing chamber 110, which can mix with the gas entering the mixing chamber 110 from the adjacent second pipes 400. This mixes the gas closer to the axis of the precursor pipe 200, improving the uniformity of the mixed gas flow exiting the outlet pipe 500 and reducing the risk of backfire during flame synthesis.

[0039] Further, please refer to Figure 4As shown, in some embodiments, the flame synthesis apparatus 10 includes an even number of first pipes 300 and an even number of second pipes 400. Each first pipe 300 is centrally symmetrical about the axis of the precursor pipe 200, and each second pipe 400 is centrally symmetrical about the axis of the precursor pipe 200. Gas entering the mixing chamber 110 through the centrally symmetrical first pipes 300 can form a swirling flow along the same rotation direction. Another portion of the gas entering the mixing chamber 110 through the centrally symmetrical second pipes 400 can drive the swirling flow formed by adjacent first pipes 300 to move closer to the axis of the precursor pipe 200. This allows multiple swirling flows to approach the axis of the precursor pipe 200 and further mix with the liquid precursor aerosol in the mixing chamber 110, thereby improving the uniformity of the mixed gas flow exiting the mixing outlet 120 along the radial direction of the mixing outlet 120 and further reducing the risk of backfire.

[0040] Without departing from the inventive concept of this invention, those skilled in the art can further improve the flame synthesis apparatus 10.

[0041] As a preferred option, please refer to Figure 3 As shown, in some embodiments, the flame synthesis apparatus 10 further includes an outlet pipe 500, which includes an outlet receiving end 510 and an outlet output end 520. The outlet receiving end 510 is connected to the mixing chamber 100. The outlet pipe 500 also has an outlet channel 530 extending along a first direction. The outlet channel 530 includes a first conveying section 540 and a second conveying section 550 distributed along the first direction. The inner walls of the first conveying section 540 and the second conveying section 550 are smoothly connected. The first conveying section 540 forms a mixing output port 120 at the outlet receiving end 510, and the second conveying section 550 forms an outlet output port 560 at the outlet output end 520. Along the first direction, the diameter of the second conveying section 550 gradually decreases.

[0042] Through the above scheme, the mixed airflow in the mixing chamber 110 can enter the outlet channel 530 through the mixing outlet 120 and continue to move along the first direction. During the flow of the airflow located in the outlet channel 530, the movement perpendicular to the first direction is restricted by the inner wall of the outlet channel 530. The velocity component of the mixed airflow perpendicular to the first direction is attenuated during the flow, reducing the tangential flow of the mixed airflow and improving the stability of the mixed airflow, which is beneficial to improving the stability of the flame synthesis process. Since the diameter of the second conveying section 550 gradually decreases along the first direction, the mixed airflow can be accelerated by the second conveying section 550 when moving along the first direction, thereby reducing the possibility of flashback.

[0043] Further, please refer to Figure 3As shown, in some embodiments, the flame synthesis apparatus 10 further includes a filter 600, which is disposed within the first conveying section 540 to separate the first conveying section 540 into a first sub-conveyor section 541 and a second sub-conveyor section 542 arranged along a first direction. Through this scheme, when the mixed airflow flows through the filter 600, the inner wall of the mesh extending along the first direction can further restrict the movement of the mixed airflow perpendicular to the first direction, thereby reducing the tangential flow of the mixed airflow, improving the stability of the mixed airflow, and thus contributing to improving the stability of the flame synthesis process.

[0044] Based on the above plan, please refer to Figure 3 As shown, in some embodiments, the flame synthesis apparatus 10 further includes a honeycomb tube 700 disposed within the second sub-conveying section 542. The mixed airflow flowing through the filter 600 can flow in a first direction through the honeycomb tube 700 disposed within the second sub-conveying section 542. The inner wall of the honeycomb holes can further restrict the tangential flow of the mixed airflow, improving the stability of the mixed airflow and thus enhancing the stability of the flame synthesis process.

[0045] Furthermore, in some embodiments, the pore size of the honeycomb tube 700 is smaller than that of the filter screen 600. Through the above approach, the inner wall of the honeycomb pores can further restrict the tangential flow of the mixed gas, improve the stability of the mixed gas flow, and thus enhance the stability of the flame synthesis process.

[0046] Further, please refer to Figure 3 As shown, in some embodiments, the inner wall of the mixing chamber 110 is smoothly connected to the inner wall of the outlet pipe 500. Along the first direction, the cross-sectional area of ​​the mixing chamber 110 gradually decreases, and the first pipe 300 and the second pipe 400 are spaced apart from the outlet pipe 500 in the first direction. Through this design, the airflow can be accelerated by the gradually narrowing mixing chamber 110 as it moves along the first direction, thereby reducing the possibility of backfire. The airflow can enter the outlet channel 530 more smoothly from the mixing chamber 110, reducing turbulence and thus improving the stability of the mixed airflow.

[0047] Without departing from the inventive concept of this invention, those skilled in the art can adjust the relative positions of the outlet channel 530 and the precursor channel 230. In some embodiments, the axis of the outlet channel 530 and the axis of the precursor channel 230 are spaced apart in a direction perpendicular to the first direction.

[0048] As a preferred option, please refer to Figure 3 As shown, where Figure 3The axes of the outlet channel 530 and the precursor channel 230 are shown in dashed lines. In some embodiments, the axis of the outlet channel 530 coincides with the axis of the precursor channel 230. Because the axis of the outlet channel 530 coincides with the axis of the precursor channel 230, the liquid precursor aerosol entering the mixing chamber 110 from the precursor channel 230 can directly enter the outlet channel 530 after mixing with the circumferential fuel gas and oxidant, reducing turbulence generation and thus improving the stability of the mixed gas flow.

[0049] In some embodiments, the flame synthesis apparatus 10 further includes a protective conduit 800, which is sleeved outside the outlet conduit 500 and together with the outlet conduit 500 defines a protective channel 810 extending in a first direction. The protective channel 810 forms a protective outlet 830 on one side in the first direction and a protective receiver 820 on the opposite side in the first direction, for receiving inert gas. Through this scheme, inert gas can flow out through the protective channel 810 to the circumference of the outlet conduit 530, thereby surrounding the mixed gas flow out of the outlet conduit 530. During the combustion of the mixed gas flow outside the outlet conduit 560, the inert gas continuously flowing out of the protective channel 810 can isolate the mixed gas flow from the outside air, thereby ensuring the stability of the flame synthesis.

[0050] In some embodiments, the first pipe 300 and the second pipe 400 are respectively provided with needle valves. By rotating the needle valves, the gas flow rate introduced into the mixing chamber 110 through the first pipe 300 and the second pipe 400 can be further fine-tuned, which facilitates the control of the flame synthesis process.

[0051] Please refer to Figure 3 As shown, in some embodiments, in the first direction, the first output terminal 320 and the second output terminal 420 are connected to the side of the mixing chamber 100 near the precursor pipe 230. With this design, the oxidant and fuel entering the mixing chamber 110 from the first output terminal 320 and the second output terminal 420 can flow a longer distance in the mixing chamber 110 along the first direction after mixing with the liquid precursor aerosol, which is beneficial for a more uniform mixing of the oxidant, fuel, and liquid precursor.

[0052] Please refer to Figures 1 to 5 As shown, the present invention also proposes a flame synthesis method, which is executed using the flame synthesis apparatus 10 of any of the above embodiments, and specifically includes the following steps: Oxidant is continuously introduced from one of the first receiving port 340 and the second receiving port 440, and fuel is continuously introduced from the other. Liquid precursor aerosol is continuously introduced into the precursor channel 230 from the precursor receiving port 240, so that oxidant, fuel and liquid precursor aerosol form a mixed gas flow in the mixing chamber 110. A stagnation plate 20 is provided on one side of the flame synthesis device 10 where a mixing output port 120 is provided, and the mixed gas flow from the mixing output port 120 is ignited.

[0053] Through the above scheme, when the premixed gas flowing out of the mixing outlet 120 is combusted, the liquid precursor undergoes rapid heating at the flame front, followed by rapid cooling due to contact with the stagnation plate 20, and nanomaterials are generated on the surface of the stagnation plate 20. Since the inner wall of the first pipe 300 is tangent to the inner wall of the mixing chamber 110, the gas entering the mixing chamber 110 from the first pipe 300 can flow along the inner wall of the mixing chamber 110. Furthermore, since the extension direction of the first pipe 300 forms an angle with the first direction, the airflow flowing along the inner wall of the mixing chamber 110 can further form a swirling flow around the axis of the precursor pipe 200. In the direction perpendicular to the first direction, the portion of the swirling flow near the inner side of the precursor pipe 200 mixes with the liquid precursor aerosol. Furthermore, since the extension direction of the second pipe 400 is toward the axis of the precursor pipe 200, the gas entering the mixing chamber 100 from the second pipe 400 and mixing with the swirling flow can bring the swirling flow closer to the axis of the precursor pipe 200. This allows the fuel and oxidant introduced from the first pipe 300 and the second pipe 400 to mix further with the liquid precursor aerosol, improving the uniformity of the mixed gas flow out of the mixing outlet 120 along the radial direction of the mixing outlet 120. The mixed gas flow is less prone to backfire during combustion, and the safety of the laminar premixing flame retardation technology using the liquid precursor is higher.

[0054] To facilitate understanding by those skilled in the art, the process of synthesizing nanomaterials using liquid-phase precursors is further described below with reference to specific embodiments.

[0055] Prepare a mixed aqueous solution by mixing chromium nitrate, manganese nitrate, ferric nitrate, cobalt nitrate, and nickel nitrate in a molar ratio of 1:1:1:1:1, with each metal ion having a concentration of 0.1 mol / L, and inject it into the nebulizer for later use.

[0056] Please refer to Figure 5 As shown, methane, oxygen, and air are first introduced into the two first receiving ports 340 and the two second receiving ports 440, respectively, with a methane flow rate of 1.700 L / min, an oxygen flow rate of 1.313 L / min, and an air flow rate of 20 L / min.

[0057] Then, use an electric spark igniter to continuously ignite at a distance of about 5 mm from the stagnation plate, while slowly reducing the air flow rate until the gas is ignited and a stable stagnation flame is formed under the substrate; continue to reduce the air flow rate to the preset value of 9.737 L / min.

[0058] After the flame stabilizes, the atomizing device is turned on to atomize the precursor solution. Using nitrogen gas at a flow rate of 4.250 L / min as the carrier gas, the formed liquid precursor aerosol is introduced into the precursor receiving port 240. After being uniformly mixed with the premixed gas, it is rectified and sprayed out from the outlet port 560. At this time, a bright lumen can be observed in the flame zone.

[0059] The flow distribution along the tangential direction and directly opposite the inlet can be finely adjusted by rotating the needle valve until the mixed airflow at the outlet 560° is uniformly distributed radially and the flame is stable without violent vertical shaking. The nanoparticles generated by the reaction are deposited on the substrate surface, and the high-entropy oxide (Cr, Mn, Fe, Co, Ni)3O4 nanoparticles will be collected by scraping later.

[0060] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A flame synthesis apparatus, characterized in that, include: A mixing chamber having a mixing cavity forming a mixing outlet in a first direction of the mixing chamber; The precursor pipeline includes a precursor receiving end and a precursor output end, and also has a precursor channel. The precursor output end is connected to the side of the mixing chamber opposite to the first direction. The precursor channel forms a precursor receiving port at the precursor receiving end and a precursor output port at the precursor output end. The precursor receiving port is used to introduce liquid-phase precursor aerosol, and the precursor output port is connected to the mixing chamber. The first conduit includes a first receiving end and a first output end, and also has a first channel. The first output end is connected to the mixing cavity. The first channel forms a first receiving port at the first receiving end and a first output port at the first output end. The first output port is connected to the mixing chamber. The second conduit includes a second receiving end and a second output end, and also has a second channel. The second output end is connected to the mixing cavity. The second channel forms a second receiving port at the second receiving end and a second output port at the second output end. The second output port is connected to the mixing chamber. Wherein, one of the first receiving port and the second receiving port is used to introduce fuel, and the other is used to introduce oxidant; the extension direction of the first pipe and the extension direction of the second pipe are both at an angle to the first direction; the inner wall of the first channel is tangent to the inner wall of the mixing chamber, and the extension direction of the second channel is toward the axis of the precursor channel.

2. The flame synthesis apparatus according to claim 1, characterized in that, The flame synthesis apparatus includes a plurality of first pipes and a plurality of second pipes, which are arranged circumferentially along the precursor pipes.

3. The flame synthesis apparatus according to claim 2, characterized in that, Multiple first pipes and multiple second pipes are arranged alternately along the circumference of the precursor pipes.

4. The flame synthesis apparatus according to claim 3, characterized in that, The flame synthesis apparatus includes an even number of first pipes and an even number of second pipes, each of the first pipes being centrally symmetrical about the axis of the precursor pipe, and each of the second pipes being centrally symmetrical about the axis of the precursor pipe.

5. The flame synthesis apparatus according to claim 1, characterized in that, The flame synthesis device further includes an outlet pipe, which includes an outlet receiving end and an outlet output end, the outlet receiving end being connected to the mixing chamber; The outlet pipe also has an outlet channel extending along the first direction. The outlet channel includes a first conveying section and a second conveying section distributed along the first direction. The inner walls of the first conveying section and the second conveying section are smoothly connected. The first conveying section forms the mixed output port at the outlet receiving end, and the second conveying section forms the outlet output port at the outlet output end. Along the first direction, the diameter of the second conveying section gradually decreases.

6. The flame synthesis apparatus according to claim 5, characterized in that, The flame synthesis apparatus further includes a filter screen disposed within the first conveying section to divide the first conveying section into a first sub-conveying section and a second sub-conveying section arranged along the first direction.

7. The flame synthesis apparatus according to claim 6, characterized in that, The flame synthesis device also includes a honeycomb tube, which is disposed within the second sub-conveying section; The pore size of the honeycomb tube is smaller than that of the filter screen.

8. The flame synthesis apparatus according to claim 5, characterized in that, The inner wall of the mixing chamber is smoothly connected to the inner wall of the outlet pipe; Along the first direction, the cross-sectional area of ​​the mixing chamber gradually decreases, and the first pipe and the second pipe are spaced apart from the outlet pipe in the first direction.

9. The flame synthesis apparatus according to claim 5, characterized in that, The axis of the outlet channel coincides with the axis of the precursor channel.

10. A flame synthesis method, characterized in that, Performed using the flame synthesis apparatus according to any one of claims 1 to 9, comprising: Oxidant is continuously introduced from one of the first receiving port and the second receiving port, and fuel is continuously introduced from the other. Liquid precursor aerosol is continuously introduced into the precursor channel from the precursor receiving port, so that the oxidant, the fuel and the liquid precursor aerosol form a mixed gas flow in the mixing chamber. A stagnation plate is provided on the side of the flame synthesis device where the mixing output port is located, and the mixed gas flow from the mixing output port is ignited.

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