An integrated production system for nanoparticle-doped flame synthesis and collection

Abstract

The present invention provides an integrated production system for flame synthesis and collection of nanoparticle doping. By arranging a plurality of combined burners and atomizer combinations at the top of the flame chamber, and each atomizer being independent of each other, it realizes the separate preparation, atomization of the precursor solution and the flame synthesis of nanoparticles, avoiding the problems that the doping ratio is not easy to control due to the mutual influence of the solubility of different metal ions when mixing the precursor solutions, and the atomizer is prone to blockage. The arrangement of the plurality of combined burners and atomizers can also effectively improve the production capacity in the production of a single nanoparticle; at the same time, the setting of the frustum filter screen, conical filter screen and spiral scraper can effectively improve the collection rate of nanoparticles. On the premise that the production system of the present invention realizes effective controllability of the proportion of doped nanoparticles and uniform mixing of different nanoparticles, it simplifies the production process, improves the production efficiency and production capacity, and reduces the production cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterial synthesis, and particularly relates to an integrated production system for doping and collecting nanometer particles by flame synthesis. Background Art

[0002] Modern nanotechnology is crucial for the fields of medicine, catalysis, electronics, and materials. Nanometer particles have unique performance advantages in many fields due to their small particle size and large specific surface area. Currently, nanometer particles are mainly synthesized by methods such as flame synthesis, chemical vapor deposition, sol-gel method, liquid precipitation method, hydrothermal method, and plasma spraying. Among them, the flame synthesis method has the advantages of easy large-scale implementation, no waste liquid, small particle size of nanometer particles, and easy doping.

[0003] The patent document "A system and method for synthesizing nanometer particles by swirling stagnation flame" with the publication number CN103464064 A discloses a system for synthesizing nanometer particles by flame, which has the characteristics of simple burner structure and process, uniform particle size, and high purity. However, this system is only applicable to the synthesis of single types of precursors and nanometer particles, and the production capacity of individual burners is small, which limits the production demand of nanometer particles.

[0004] The traditional preparation method of doped nanometer particles is to prepare the corresponding nanometer particles separately, and then mix different nanometer particles according to the doping ratio. However, the mixing uniformity of the doped nanometer particles obtained by this mixing method is poor and cannot meet the usage requirements.

[0005] The patent document "A nanometer particle swirling flame atomization doping synthesis system and its synthesis method" with the publication number CN110465257 A, although the disclosed nanometer particle swirling flame atomization doping synthesis system can achieve the doping of multiple nanometer particles, it is necessary to configure several corresponding metal salt solutions in the precursor liquid. Affected by the solubility of metal salts and their chemical properties, when the concentration is high, solid precipitation is likely to occur, blocking the atomizer; when the concentration is low, the production capacity of a single atomizer is small, which limits the promotion of industrialization.

[0006] The patent document "An atomization flame nanometer particle synthesis system based on multi-swirl enhanced mixing" with the publication number CN107511123 A prepares doped nanometer particles by the form of atomizing and burning various independently configured precursor liquids. However, in this way, the contact of several precursor liquids is still inevitable at the outlet of the atomizer, and phenomena such as precipitation and coking are likely to occur at the outlet position of the atomizer, which limits the long-term stable operation of the device.

[0007] With the further development of flame synthesis technology, flame synthesis technology has entered a new stage from laboratory preparation to industrial application, and the structure and parameters of flame synthesis equipment need to be further adjusted and optimized. How to improve the mixing uniformity of different nanoparticles in doped nanoparticles, while increasing the synthesis yield of nanopowder particles, and achieve safe, stable and flexible operation under the conditions of production amplification; how to achieve the stability of equipment operation during flame synthesis, avoid the blockage of the atomizer caused by solid precipitation or coking during the synthesis process, and achieve uniform doping of different nanoparticles under the premise of expanding production capacity; how to optimize the collection device of nanoparticles to achieve stable operation of the entire process device and have a high collection rate, have always been key technical issues that need to be solved in the field of flame synthesis. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the present invention provides an integrated production system for doped flame synthesis and collection of nanoparticles. By arranging multiple combined burners and atomizers at the top of a flame chamber, and passing different precursors into corresponding atomizers respectively, it is possible to achieve separate configuration, atomization and combustion of multiple precursors, and then mix them in the flame chamber, and collect them by the filter under the action of negative pressure, and finally separate and collect the nanoparticles from the filter by rotating the spiral scraper. The production system of the present invention can effectively improve the mixing uniformity of doped nanoparticles, and at the same time improve the collection efficiency and collection rate of nanoparticles; when the precursors passed into all atomizers are the same, the production system of the present invention can be used to expand the production capacity of nanoparticles.

[0009] A nanoparticle doping flame synthesis and collection integrated production system, comprising:

[0010] A tubular flame chamber with a cover plate on the top, a discharge port at the bottom of the flame chamber; a motor is provided in the center of the cover plate, and the output end of the motor is connected to a spiral scraper;

[0011] A plurality of combined burners are arranged on the cover plate, each of which has an atomizer at its center; the plurality of combined burners are evenly arranged in a circular parallel form with the motor as the center;

[0012] An inverted truncated cone filter is provided in the middle section of the flame chamber, and the upper and lower edges of the truncated cone filter are respectively connected to the inner wall of the flame chamber; a plurality of negative pressure suction ports connected to an external vacuum device are provided on the side wall of the flame chamber corresponding to the truncated cone filter;

[0013] A conical filter is coaxially arranged inside the truncated cone filter, and the lower end of the conical filter is connected to an external vacuum device through a negative pressure pipe; the truncated cone filter and the conical filter together define an annular channel whose width gradually decreases from top to bottom;

[0014] Above the frustum-shaped filter screen in the flame chamber, a vane deflector ring is provided. The vane deflector ring includes a central ring coaxially arranged with the flame chamber and inclined vanes evenly distributed circumferentially along the central ring.

[0015] The spiral scraper is located in the annular channel, and its inner and outer structures are respectively matched with the conical filter screen and the frustum-shaped filter screen, and there are gaps between the spiral scraper and the conical filter screen and the frustum-shaped filter screen respectively.

[0016] In the above structure, the inclined filter screen surfaces of the frustum-shaped filter screen and the conical filter screen are used to form a downwardly contracting annular gas channel in the flame chamber, enabling the gas-solid mixture to come into full contact with the filter screen and realizing effective gas-solid separation. The negative pressure extraction port and the negative pressure pipeline are respectively connected to an external vacuum device. When the vacuum device operates, a negative pressure area is formed between the frustum-shaped filter screen and the inner wall of the flame chamber and inside the conical filter screen, creating a pressure difference on both sides of the filter screen to provide a driving force for filtering nanoparticles.

[0017] The gap between the spiral scraper and the filter screen (frustum-shaped filter screen and conical filter screen) can enable nanoparticles to form a nano-particle filter layer with a fixed thickness on the surface of the filter screen, realizing a stable filter pressure difference environment. Based on the action of the nano-particle layer, the interception efficiency of nanoparticles can be effectively improved, and the collection rate of the product can be increased. The vacuum device can be a vacuum fan or other devices capable of pumping vacuum.

[0018] The setting of the vane deflector ring can prevent the airflow ejected by the combined burner from being too concentrated and concentrated in contact with the filter screen directly below the combined burner, resulting in uneven thickness distribution of the nano-particle bed layer on the surface of the filter screen. The inclined vanes can play a role in guiding and mixing the airflow vertically ejected by each combined burner and form a swirling gas entering the surface of the filter screen, improving the uniformity of the mixing of doped nanoparticles and the uniformity of the thickness of the nano-particle bed layer on the surface of the filter screen.

[0019] The present invention can achieve independent preparation, atomization, and combustion of different precursors without interference by arranging a plurality of independent combined burners and atomizer combinations at the top of the flame chamber. The nanoparticles synthesized by the combustion of different precursors and the combustion flue gas form a high-temperature nanoparticle stream (gas-solid mixture). Driven by negative pressure, different high-temperature nanoparticle streams move downward in the flame chamber. During this process, the gas-solid mixture forms a swirl through the vane guide ring and is evenly distributed on the cross-section of the flame chamber, while achieving sufficient mixing of different nanoparticles to form doped nanoparticles. When passing through the frustum-shaped filter screen and the conical filter screen, the nanoparticles are intercepted, and the gas is extracted from the flame chamber. When the thickness of the nanoparticle bed layer on the filter screen exceeds the clearance width between the spiral scraper and the filter screen, the nanoparticles exceeding the thickness are scraped off by the spiral scraper driven by the motor, so that the bed layer thickness is maintained at a fixed thickness, ensuring a suitable and stable pressure drop inside and outside the system, and improving the collection efficiency and collection rate. Since each nanoparticle is independently synthesized, the proportion of different nanoparticles in the formed doped nanoparticles is accurately controllable, and sufficient mixing can be achieved in the flame chamber to form uniformly dispersed doped nanoparticles.

[0020] The vane guide ring can be fixed by connecting its central ring to the top of the flame chamber or by connecting each vane to the inner wall of the flame chamber.

[0021] The conical filter screen can be fixed in the flame chamber through the vacuum pipeline connected to it.

[0022] Preferably, the atomizer has a two-fluid flow channel structure, with a precursor solution channel in the center and an atomizing gas channel outside; the atomizer is provided with a precursor solution inlet and an atomizing gas inlet corresponding to and communicating with the aforementioned two channels.

[0023] Preferably, there are 3 to 10 combined burners. More preferably, there are 3 to 8.

[0024] Preferably, the atomizer is connected to the combined burner in the form of internal and external threads. This connection method has good sealing performance, is not only convenient for installation and disassembly, but also can adjust the installation height to adapt to the equipment parameter requirements of different products.

[0025] Preferably, the outside of the atomizer is provided with a detachable silica gel sealing cover. During the operation of the device, the disassembly, assembly, and position adjustment of a single atomizer can be realized, and there is no material exchange with the external environment, ensuring the safety and reliability of replacement.

[0026] Preferably, the spiral scraper can freely lift in the flame chamber to adjust the clearance size between it and the frustum-shaped filter screen and the conical filter screen.

[0027] Preferably, the gap between the spiral scraper and the conical filter screen and the tubular filter screen is independently selected from 5 to 20 mm. The size of this gap can be appropriately adjusted according to the required bed pressure drop in actual use (for example, it can be achieved by raising or lowering the spiral scraper).

[0028] Preferably, the height of the flame chamber is 2 to 4 times the height of the flame to ensure the initial dispersion of the high-temperature gas after flame synthesis.

[0029] Preferably, one or more sets of vane guide rings can be provided, and the inclination angle of the vanes is 35 to 70°. This can achieve gas distribution and mixing under different gas volumes and doping conditions. The gas after diversion enters the wire mesh filter in a swirling state. The vane inclination means tilting in the vertical plane with the center line in the length direction of the vane as the axis.

[0030] When the distance between adjacent combined burners is too large, the equipment size will be large, increasing the equipment cost; when it is too small, they will affect each other during the flame synthesis of the precursor. Preferably, the distance between two adjacent combined burners is 0.2 to 0.6 m. The distance between two adjacent combined burners refers to the distance between the centers of the combined burners.

[0031] Preferably, the distance between the combined burner and the inner wall of the flame chamber is 0.2 to 0.6 m. The distance between the combined burner and the inner wall of the flame chamber refers to the distance between the center of the combined burner and the inner wall of the flame chamber.

[0032] The diameter of the flame chamber is adjusted according to the actual number of combined burners required, or an appropriate number of combined burners is set according to the diameter of the flame chamber.

[0033] Preferably, the number of negative pressure air extraction ports is the same as the number of combined burners and their positions correspond.

[0034] Preferably, the width of the lower end of the annular channel is 15 to 30 cm. While meeting the feeding requirement without blockage, it realizes the contraction of the gas, enables the gas to fully contact the filter screen, and achieves rapid gas-solid separation.

[0035] Preferably, the combined burner includes an annular swirl burner and an annular gas guide block sequentially sleeved outside the atomizer; a plurality of combustion-supporting gas channels and a plurality of fuel gas channels penetrating radially through the gas guide block are provided, and the combustion-supporting gas channels and the fuel gas channels are alternately and evenly distributed circumferentially along the swirl burner; the number of fuel gas channels is the same as the number of combustion-supporting gas channels. It should be noted that the outer side of the annular gas guide block can be of any shape, such as circular, polygonal, etc.

[0036] As a further preference, the swirl burner is composed of a plurality of combustion modules, and a swirl air inlet channel is formed between two adjacent combustion modules. Each swirl air inlet channel is communicated with an auxiliary air channel or a fuel gas channel; the sum of the numbers of the auxiliary air channels and the fuel gas channels is equal to the number of the swirl air inlet channels. The auxiliary air and the fuel gas respectively enter the swirl burner through the corresponding channels to form a swirl air flow, and the fuel gas is ignited to form a stable swirl pilot flame.

[0037] As a further preference, 3 to 5 auxiliary air channels and fuel gas channels are respectively provided.

[0038] As a preference, the filtration precisions of the frustum filter screen and the conical filter screen are respectively 0.2 to 3 μm, and the filtration areas are respectively 4 to 20 m 2 . Of course, the filtration precision and the filtration area can be appropriately adjusted according to the size of the equipment.

[0039] As a preference, the discharge port of the flame chamber is connected to a screw conveyor, and a discharge packaging port is arranged on the lower side of one end of the screw conveyor away from the flame chamber. The screw conveyor is a complete set of devices that can achieve sealed conveying and collection. The arrangement of the screw conveyor realizes the fully automatic integrated continuous production of nanoparticle synthesis, the uninterrupted output of nanoparticle production, and the non-contact of the product with the external environment, which can ensure that the whole-flow product is not polluted by the external environment and improve the output at the same time.

[0040] As a preference, a cooling jacket is sleeved on the outer side of the middle and upper part of the flame chamber. The cooling jacket is used for preliminarily cooling the high-temperature gas-solid mixture. A cooling water inlet is arranged at the lower end of one side of the cooling jacket, and a cooling water outlet is arranged at the upper end of the corresponding side.

[0041] As a preference, a plurality of circular cooling coils are respectively arranged on the outer wall of the frustum filter screen and the inner wall of the conical filter screen. The cooling coils can play a role in cooling the corresponding filter screen and the gas, which is convenient for adsorption and filtration.

[0042] As a preference, a sight hole is arranged on the upper side wall of the flame chamber to observe the reaction situation of flame synthesis.

[0043] As a preference, the lower part of the flame chamber is a funnel-shaped blanking chamber. The blanking chamber is a gravity sedimentation collection area for nanoparticles, and the upper blanking port is the bottom of the annular channel. The nanoparticles scraped off by the spiral scraper enter the blanking chamber through the blanking port.

[0044] The production system of the present invention realizes the processes of flame synthesis reaction, nanoparticle filtration collection and transportation from top to bottom, optimizes the production process, reduces the production cost, and the equipment operates stably, and various process indexes are controllable.

[0045] A method for flame synthesis of nanoparticles, which is produced by using the above integrated production system for doped flame synthesis and collection of nanoparticles, includes the following steps:

[0046] (1) The auxiliary gas and the fuel gas are respectively introduced into the corresponding combined burner through the auxiliary gas channel and the fuel gas channel to form a swirling air flow, and the fuel gas is ignited to form a stable swirling pilot flame;

[0047] (2) The precursor solution and the atomizing gas are introduced into the atomizer through the precursor inlet and the atomizing gas inlet, and the precursor solution is atomized into precursor droplets in the atomizer;

[0048] (3) The precursor droplets move downward into the stable swirling pilot flame, are ignited and synthesized into nanoparticles. The nanoparticles and the combustion gas form a high-temperature nanoparticle stream (gas-solid mixture) along it. The high-temperature nanoparticle stream moves downward under the drive of negative pressure for preliminary cooling, and then when passing through the frustum-shaped filter screen and the conical filter screen, various doped nanoparticles are intercepted and collected by the filter screen;

[0049] (4) The spiral scraper rotates under the drive of the motor. When the nanoparticle bed layer on the surface of the filter screen exceeds the gap between the spiral scraper and the filter screen, the excess nanoparticles are scraped off and enter the blanking chamber through the blanking port.

[0050] In the above step (1), since each combined burner is provided with a plurality of auxiliary gas channels and a plurality of fuel gas channels, and the auxiliary gas channels and the fuel gas channels are arranged in a circumferential uniform distribution and spaced in turn to form a combustion module. The combustion modules are close to each other, can form a concentric circular ring surrounding the atomizer, and a swirling air inlet channel is formed between the walls of two adjacent combustion modules, and the swirling air flow enters the center of the burner to form a swirling air flow, and the fuel gas in the swirling air flow is ignited to form a stable swirling pilot flame.

[0051] In step (2), the particle size of the precursor droplets can be adjusted by the relative flow rate and pressure of the precursor liquid outlet and the atomizing gas outlet.

[0052] In step (2), when preparing doped nanoparticles, a form of introducing one precursor solution into one atomizer is adopted, and the precursor solutions introduced into two adjacent atomizers are different.

[0053] In step (3), the doping ratio can be controlled by adjusting the flow rate and concentration of the precursor solution.

[0054] Compared with the prior art, the beneficial effects of the present invention are:

[0055] The integrated production system for nanoparticle doping flame synthesis and collection of the present invention realizes the separate preparation, atomization of a single precursor solution and the flame synthesis of nanoparticles by arranging a plurality of combined burners and atomizer combinations at the top of the flame chamber, with each atomizer being independent of each other. This avoids the problem that the doping ratio is not easy to control due to the mutual influence of the solubility of different metal ions when mixing precursor solutions, and the problem of easy clogging of the atomizer. The setting of multiple combined burners and atomizers can also effectively improve the production capacity in the production of a single nanoparticle; at the same time, the setting of the frustum filter screen, conical filter screen and spiral scraper can effectively improve the collection rate of nanoparticles. The production system of the present invention simplifies the production process, improves the production efficiency and production capacity, and reduces the production cost on the premise of effectively controlling the proportion of doped nanoparticles and making different nanoparticles mix evenly. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic structural diagram of an embodiment of the present invention;

[0057] Figure 2 It is a schematic diagram of the connection mode of the combined burner and the atomizer in the embodiment of the present invention;

[0058] Figure 3 It is a schematic cross-sectional structure diagram of the cooling exhaust pipe of the filter screen collection part in the embodiment of the present invention;

[0059] Figure 4 It is a schematic diagram of the installation position of the combined burner and the negative pressure air extraction port in the embodiment of the present invention;

[0060] Figure 5 It is a schematic cross-sectional structure diagram of the combined burner with 4 fuel gas channels and 4 combustion-supporting gas channels respectively arranged in the embodiment of the present invention;

[0061] Figure 6 It is a schematic diagram of the spiral scraper structure in the embodiment of the present invention;

[0062] Figure 7 It is a schematic diagram of the structure of the vane guide ring in the embodiment of the present invention;

[0063] Figure 8 It is a TEM image of Y2O3-Al2O3 nanoparticles in Application Example 1 of the present invention;

[0064] Figure 9 It is a TEM image of the silica nanomaterial prepared in Application Examples 2 and 3 and the Comparative Example of the present invention;

[0065] In the figure, 1 - motor, 2 - combined burner, 3 - atomizer, 4 - flame chamber, 5 - sight hole, 6 - vane guide ring, 601 - central ring, 602 - vane, 7a - cooling water inlet, 7b - cooling water outlet, 8 - cooling jacket, 9 - spiral scraper, 10 - conical filter screen, 11 - frustum filter screen, 12 - outer negative pressure area, 13 - central negative pressure area, 14 - negative pressure air extraction port, 15 - feeding port, 16 - negative pressure pipeline, 17 - feeding chamber, 18 - screw conveyor, 19 - discharging and packaging port, 20 - cooling coil in the outer negative pressure area, 21 - cooling coil in the central negative pressure area, 22 - sealing cover, 23 - combustion module, 24 - gas guide block, 25 - fuel gas or combustion-supporting gas channel, 26 - swirling air inlet channel. Detailed implementation manners

[0066] To make the technical solutions of the present invention clearer and more understandable, the following further describes the specific implementation manners and working processes of the present invention with reference to the accompanying drawings of the specification.

[0067] The orientation terms such as up, down, left, right, front, and back in this application document are based on the positional relationships shown in the drawings. If the drawings are different, the corresponding positional relationships may also change accordingly. Therefore, it should not be understood as a limitation on the protection scope.

[0068] As Figure 1 shown, a nano-particle doped flame synthesis and collection integrated production system includes a combined burner 2, an atomizer 3, a flame chamber 4, a frustum filter screen 10, a conical filter screen 11, a spiral scraper 9, a motor 1, a feeding chamber 17, and a screw conveyor 18.

[0069] A cover plate is provided at the top of the flame chamber 4, and its lower part is a funnel-shaped feeding chamber; the top of the feeding chamber is a feeding port 16, and the bottom is a discharging port; the motor 1 is arranged at the center of the cover plate, and its output end is connected to the spiral scraper 9 located in the flame chamber 4 through a connecting shaft and can drive the spiral scraper 9 to rotate.

[0070] The combined burner 2 is installed on the top cover plate of the flame chamber 4. According to the diameter of the flame chamber 4, 2 or more combined burners can be set. Multiple combined burners 2 are evenly distributed in a ring-shaped parallel connection form, and the actual number can be adjusted according to production needs; the combined burner 2 includes an annular swirling burner and an annular gas guide block 24 that are sequentially sleeved outside the atomizer 3; the gas guide block 24 is provided with a plurality of combustion-supporting gas channels 25 and a plurality of fuel gas channels 25 that penetrate radially through it. The combustion-supporting gas channels 25 and the fuel gas channels 25 are alternately and evenly distributed along the circumferential direction of the swirling burner; the number of the fuel gas channels 25 is the same as the number of the combustion-supporting gas channels 25.

[0071] The swirl burner is composed of multiple combustion modules 23. A swirl air intake channel 26 is formed between two adjacent combustion modules 23. Each swirl air intake channel 26 communicates with an auxiliary gas channel 25 or a fuel gas channel 25; the sum of the numbers of the auxiliary gas channels 25 and the fuel gas channels 25 is equal to the number of the swirl air intake channels 26. The number of the auxiliary gas channels and the fuel gas channels is respectively set to be 3 - 5. As Figure 5 shown is a schematic structural diagram of a combined burner with 4 fuel gas channels and 4 auxiliary gas channels respectively.

[0072] The atomizer 3 is installed at the center of the combined burner 2 in a form of threaded connection (as Figure 2 shown). Similarly, there are also multiple atomizers 3, and each atomizer 3 corresponds to a combined burner 2. The atomizer 3 has a dual-fluid flow channel structure, with a precursor solution channel in the center and an atomizing gas channel on the outside; the atomizer 3 is provided with a precursor solution inlet and an atomizing gas inlet corresponding to and communicating with the aforementioned two channels. The atomizer 3 is connected to the combined burner 2 in a form of internal and external threads, which is convenient for installation and disassembly and can adjust the installation height; a detachable silica gel sealing cover 22 is arranged outside the atomizer 3. During the operation of the device, the disassembly, installation and adjustment of a single atomizer 3 can be realized, and there is no material exchange with the external environment.

[0073] Above the inner conical filter screen 11 in the flame chamber 4, there is a vane guide ring 6. The vane guide ring 6 consists of a central ring 601 coaxially arranged with the flame chamber 4 and inclined vanes 602 uniformly distributed along the circumferential direction of the central ring 601, as Figure 7 shown.

[0074] A sight hole 5 is arranged on the upper part of the cylinder body of the flame chamber 4 to facilitate observing the flame synthesis reaction condition.

[0075] As Figure 3 shown, a plurality of circular cooling coils are respectively arranged on the outer wall of the conical filter screen 11 and the inner wall of the conical filter screen 10, corresponding to the outer negative pressure zone cooling coil 20 and the central negative pressure zone cooling coil 21 respectively. The cooling coils can play a role in cooling the corresponding filter screen and gas, which is convenient for adsorption and filtration.

[0076] In the middle of the flame chamber 4, an inverted conical filter screen 11 is arranged. The upper and lower edges of the conical filter screen 11 are respectively connected to the inner wall of the flame chamber 4; on the side wall of the flame chamber 4 corresponding to the conical filter screen 11, there are a plurality of negative pressure air extraction ports 14 with the same number as the number of the combined burners 2. The negative pressure air extraction ports 14 are externally connected to a vacuum fan, and the distribution of the plurality of negative pressure air extraction ports 14 corresponds one by one to the plurality of combined burners 2 (see Figure 4)。A frustum-shaped filter net 11 is coaxially provided with a conical filter net 10 inside. The lower end of the conical filter net 10 is connected to an external vacuum fan through a negative pressure pipeline 16. When the vacuum fan operates, an outer negative pressure area 12 is formed between the frustum-shaped filter net 11 and the inner wall of the flame chamber 4, and a central negative pressure area 13 is formed inside the conical filter net 10.

[0077] The frustum-shaped filter net 11 and the conical filter net 10 jointly define an annular channel in the flame chamber 4 with a width gradually decreasing from top to bottom. Under the action of negative pressure, the gas-solid mixture from the flame chamber 4 passes through the downwardly contracting structure (annular channel), and the mixed gas comes into full contact with the filter nets (frustum-shaped filter net 11 and conical filter net 10). After being filtered by the filter nets, the nano-particles in the gas are intercepted.

[0078] The negative pressure areas (outer negative pressure area 12 and central negative pressure area 13) are negative pressure atmospheres formed by providing negative pressure suction through the vacuum fan, creating a pressure difference before and after the filter wire mesh, which provides a driving force for filtering nano-particles.

[0079] The spiral scraper 9 is located in the above-mentioned annular channel, and its outer and inner structures respectively match the frustum-shaped filter net 11 and the conical filter net 10 (for the specific structure, see Figure 6 ), and respectively maintain a set thickness of spacing (gap) from the frustum-shaped filter net 11 and the conical filter net 10. And by lifting the spiral scraper 9, the size of the spacing between the spiral scraper 9 and the filter net can be adjusted, thereby realizing the control of the thickness of the filter bed layer, ensuring that the pressure drop inside and outside the device is appropriate and stable, and enabling the equipment to work stably for a long time.

[0080] A cooling jacket 8 is sleeved on the outer side of the upper-middle part of the flame chamber 4. The cooling jacket 8 is used for preliminarily cooling the high-temperature gas-solid mixture. A cooling water inlet 7a is arranged at the lower end of one side of the cooling jacket 8, and a cooling water outlet 7b is arranged at the upper end of the corresponding side.

[0081] The feeding port 15 is a circular ring channel (i.e., the bottom of the above-mentioned annular channel). The nano-particle powder scraped off from the filter net by the spiral scraper 9 enters the feeding chamber 17 through this channel. The nano-particles enter the spiral conveyor 18 downward under the action of gravity in the feeding chamber 17. The spiral conveyor 18 is a complete set of devices that can achieve sealed transportation and collection. It transports the nano-particles to its discharge and packaging port 19 for packing and transfer, thereby realizing continuous production.

[0082] Application Example 1: Flame synthesis of Y2O3 - Al2O3 nano-particles

[0083] Preparation of the precursor solution: Take aluminum nitrate nonahydrate (Al) as the first metal precursor; according to the set doping ratio, add the metal nitrate (yttrium nitrate hexahydrate) of the corresponding doping element yttrium (Y) to prepare the second precursor solution.

[0084] Two metal precursors were separately dissolved in the organic fuel ethanol, and 2-ethylhexanoic acid was added as an organic additive at the same time. The concentration of aluminum ions in the first precursor solution was 0.15 mol / L. The concentration of yttrium ions in the second precursor solution varied according to the doping ratio, with ion concentrations of 0.30 mol / L, 0.15 mol / L, and 0.09 mol / L (corresponding to doping molar ratios of 2:1, 1:1, and 3:5 respectively).

[0085] The above production system with 8 annular parallel combined burners and atomizers was adopted. Among them, the first precursor solution was introduced into four atomizers, and the flow rate of the first precursor solution in each atomizer was 5 L / h. The remaining four atomizers were introduced with the second precursor solution, and the flow rate of the second precursor solution in each atomizer was 5 L / h, and the precursor solutions introduced into adjacent two atomizers were different. The fuel gas used in each combined burner was methane with a flow rate of 0.8 L / min; the combustion-supporting gas and atomizing gas were compressed air with flow rates of 6 L / min and 45 L / min respectively, and the combustion power was 3 - 5 KW. By using the above method, the two precursor solutions were introduced into the atomizer at intervals, and flame synthesis was carried out to collect the prepared Y2O3-Al2O3 nanoparticles, and the production rate reached more than 1000 g / h.

[0086] The TEM image of the above-prepared Y2O3-Al2O3 nanoparticles is as Figure 8 shown. From Figure 8 it can be seen that for the morphology of the above-prepared nanoparticles, as the yttrium ion doping decreases, the particles transform from an irregular shape to a regular spherical shape, and the particle size distribution is relatively uniform; and the yttrium nanoparticles are evenly dispersed in the Al2O3 nanoparticles.

[0087] Application Example 2: Flame synthesis of silica nanomaterials (I)

[0088] The precursor silicate (hexamethyldisiloxane HMDSO) was dissolved in the organic fuel ethanol to prepare a precursor solution, in which the concentration of silicon ions was 0.8 mol / L. The fuel gas used in a single combined burner was methane with a flow rate of 0.8 L / min; the combustion-supporting gas and atomizing gas were compressed air with flow rates of 6 L / min and 30 L / min respectively, and the combustion power was 3 - 5 KW.

[0089] Using the above production system with 4 annular parallel combined burners and atomizers, the flow rate of the precursor solution in each atomizer was 3 L / h, and the production efficiency of preparing silica nanoparticles could reach more than 500 g / h. The BET measurement showed that the specific surface area of the particles was 250.57 m 2 / g, and the average particle size reached 10.88 nm. The morphology TEM of the silica nanoparticle product is as Figure 9As shown in Application Example 2. Parallel production has little impact on the properties of the product. The prepared silica nanoparticles are regular spherical in shape, with small particle size and uniform distribution.

[0090] Application Example 3: Flame synthesis of silica nanomaterials (II)

[0091] The precursor silicate (hexamethyldisiloxane HMDSO) is dissolved in the organic fuel ethanol to prepare a precursor solution, where the silicon ion concentration is 0.8 mol / L. The fuel gas used in a single combined burner is methane, with a flow rate of 0.8 L / min; the combustion-supporting gas and the atomizing gas are compressed air, with flow rates of 6 L / min and 30 L / min respectively, and the combustion power is 3 - 5 KW.

[0092] Using the above production system with 8 annular parallel combined burners and atomizers, the flow rate of the precursor solution for each atomizer is 3 L / h, and the production efficiency of preparing silica nanoparticles can reach more than 1000 g / h. The BET measurement shows that the specific surface area of the particles is 287.68 m 2 / g, and the average particle size reaches 9.48 nm. The morphology of the silica nanoparticle product by TEM is as shown in Figure 9 Application Example 3.

[0093] Comparative Example 1: Flame synthesis of silica nanomaterials

[0094] The precursor silicate (hexamethyldisiloxane HMDSO) is dissolved in the organic fuel ethanol to prepare a precursor solution, where the silicon ion concentration is 0.8 mol / L. The fuel gas used in a single combined burner is methane, with a flow rate of 0.8 L / min; the combustion-supporting gas and the atomizing gas are compressed air, with flow rates of 6 L / min and 30 L / min respectively, and the combustion power is 3 - 5 KW.

[0095] Using the above production system with 1 combined burner and atomizer, the flow rate of the precursor solution entering the atomizer is 3 L / h, and the production efficiency of preparing silica nanoparticles can reach more than 100 g / h. The BET measurement shows that the specific surface area of the particles is 265.43 m 2 / g, and the average particle size reaches 10.23 nm. The morphology of the silica nanoparticle product by TEM is as shown in Figure 9 Comparative Example 1.

[0096] Comparing Application Examples 1 and 2 and Comparative Example 1, it can be seen that setting multiple combined burners in parallel to synthesize nanoparticles has little effect on the properties (morphology, particle size, specific surface area) of the product. The prepared silica nanoparticles are regular spherical in morphology, with small particle size and uniform distribution. However, compared with only setting one combined burner and atomizer in Comparative Example 1, the form of setting multiple parallel combined burners and atomizers in Application Examples 1 and 2 can effectively improve production efficiency and reduce production costs.

Claims

1. An integrated production system for the synthesis and collection of nanoparticle doping by flame, characterized in that, Comprising: A tubular flame chamber with a cover plate at the top, and a discharge port is arranged at the bottom of the flame chamber; A motor is arranged at the center of the cover plate, and the output end of the motor is connected to a spiral scraper; A plurality of combined burners arranged on the cover plate, and an atomizer is arranged at the center of each combined burner; Centered on the motor, the plurality of combined burners are evenly arranged in a ring-shaped parallel connection form; An inverted frustum-shaped filter screen is arranged in the middle section of the interior of the flame chamber, and the upper and lower edges of the frustum-shaped filter screen are respectively connected to the inner wall of the flame chamber; A plurality of negative pressure air extraction ports connected to a vacuum device are arranged on the side wall of the flame chamber corresponding to the frustum-shaped filter screen; A conical filter screen is coaxially arranged inside the frustum-shaped filter screen, and the lower end of the conical filter screen is connected to an external vacuum device through a negative pressure pipeline; The frustum-shaped filter screen and the conical filter screen jointly define an annular channel with a width gradually decreasing from top to bottom; A blade deflector ring is arranged above the frustum-shaped filter screen in the flame chamber, and the blade deflector ring includes a central ring coaxially arranged with the flame chamber and inclined blades evenly distributed along the circumferential direction of the central ring; The spiral scraper is located in the annular channel, and its inner and outer structures are respectively matched with the conical filter screen and the frustum-shaped filter screen, and there are gaps between the spiral scraper and the conical filter screen and the frustum-shaped filter screen respectively.

2. The integrated production system for nanoparticle-doped flame synthesis and collection according to claim 1, wherein The spiral scraper can move up and down in the flame chamber.

3. The integrated production system for nanoparticle-doped flame synthesis and collection according to claim 1, wherein The gaps between the spiral scraper and the conical filter screen and the frustum-shaped filter screen are independently selected from 5 to 20 mm.

4. The integrated production system for nanoparticle-doped flame synthesis and collection according to claim 1, wherein, The distance between adjacent two combined burners and the distance between the combined burner and the inner wall of the flame chamber are independently 0.2 to 0.6 m.

5. The integrated production system for nanoparticle-doped flame synthesis and collection according to claim 1, characterized in that, The width of the lower end of the annular channel is 15 to 30 cm.

6. The integrated production system for nanoparticle doping flame synthesis and collection according to claim 1, characterized in that The combined burner includes an annular swirl burner and an annular gas guide block sequentially sleeved outside the atomizer; A plurality of combustion-supporting gas channels and a plurality of fuel gas channels penetrating radially are arranged on the gas guide block, and the combustion-supporting gas channels and the fuel gas channels are alternately and evenly distributed along the circumferential direction of the swirl burner; The number of fuel gas channels is the same as the number of combustion-supporting gas channels.

7. The integrated production system for nanoparticle doping flame synthesis and collection according to claim 6, wherein The swirl burner is composed of a plurality of combustion modules, and a swirl intake channel is formed between adjacent two combustion modules, and each swirl intake channel is communicated with a combustion-supporting gas channel or a fuel gas channel; The sum of the number of combustion-supporting gas channels and the number of fuel gas channels is equal to the number of swirl intake channels.

8. The integrated production system for nanoparticle-doped flame synthesis and collection according to claim 1, characterized in that, The filtration precision of the frustum-shaped filter screen and the conical filter screen is 0.2 - 3 μm respectively, and the filtration area is 4 - 20 m 2 .

9. The integrated production system for nanoparticle-doped flame synthesis and collection according to claim 1, characterized in that, The discharge port of the flame chamber is connected to a screw conveyor, and a discharge packaging port is arranged on the lower side of the end of the screw conveyor far away from the flame chamber.

10. The integrated production system for nanoparticle-doped flame synthesis and collection according to claim 1, wherein, A plurality of circular cooling coils are respectively arranged on the outer side wall of the frustum-shaped filter screen and the inner side wall of the conical filter screen.

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