Continuous flow preparation device for micro-nano powder material and its preparation method

Abstract

The present invention provides a continuous flow preparation device for micro-nano powder materials and a preparation method thereof. The preparation device includes an ultrasonic process intensification continuous flow reactor, and the ultrasonic process intensification continuous flow reactor includes a first liquid inlet, a second liquid inlet, a shunt mixing unit, and an ultrasonic intensification reaction unit. The shunt mixing unit includes a first liquid separation module, a second liquid separation module, and a mixing chamber for dividing a liquid into several streams. The first liquid separation module includes several first liquid separation channels, and the second liquid separation module includes several second liquid separation channels. The first liquid separation channels and the second liquid separation channels are arranged alternately at intervals. The ultrasonic intensification reaction unit includes a reaction pipeline, and the outlet of the mixing chamber is communicated with the inlet of the reaction pipeline. The technical solution of the present invention effectively realizes the spatial separation of mass transfer mixing and rapid reaction, not only meets the mass transfer requirements of rapid reaction, but also realizes continuous reaction operation, and the prepared nano powder has good stability and consistency.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder preparation, and particularly relates to a continuous flow preparation device for micro-nano powder materials and a preparation method thereof. Background Art

[0002] In a solution system, the wet chemical method for synthesizing and preparing materials through chemical reactions is one of the main means and approaches to obtain various new materials. The wet chemical method has many advantages such as mature equipment, convenient operation, easy control of composition, mild conditions, high efficiency, and large output, and has become a widely used method for preparing nano powders in current laboratories and industrial production.

[0003] The commonly used equipment for preparing nano powders by the wet chemical method is reaction vessels of various volumes. In laboratories, small-volume flasks, beakers, etc. are generally used. As the output increases, the volume of the reaction vessel is gradually enlarged until large-volume reaction kettles are used in industrial production to achieve large-scale synthesis and preparation of materials. Since the efficiency of momentum transfer, heat transfer, and mass transfer of the reaction materials changes greatly with the increase in the volume of the reaction vessel, the chemical reaction kinetic conditions for synthesizing and preparing materials also change significantly accordingly. The morphology, size, size distribution, crystallinity, yield, etc. of the synthesized and prepared materials will all change greatly. This amplification effect caused by the increase in the volume of the reaction vessel will seriously affect the industrialization transformation process and transformation success rate of the wet chemical method for preparing nano powders.

[0004] Especially for some rapid reactions where the reaction materials react upon contact, in a large-volume reaction kettle, the mass transfer and heat transfer rates are much lower than the reaction rate of forming nano particles. Coupled with the fact that the intensity of stirring and dispersion is far from sufficient to disperse the formed nano particle aggregates. As a result, in the same physical space of the reaction kettle, multiple processes such as nucleation of nano particles, dissolution of small particles, growth of large particles, aggregation between particles, and dispersion of aggregated particles occur simultaneously. Even the phenomena occurring at different positions in the same reaction kettle are different, not to mention the consistency of the phenomena in different batches of reaction kettles. This leads to large particle sizes, wide size distributions, and serious aggregation of the prepared powder particles, especially poor stability and consistency of the products between different reaction batches. More prominently, since the reaction rate of forming nano powders is very fast, while the three-transfer rate of the large-volume reaction kettle is slow, the large difference between the two rates results in not being able to reach the supersaturation required for a large number of nucleations at all. Once the reaction liquid comes into contact, new crystal nuclei are immediately generated, and the subsequent replenished reaction liquid can only promote the growth of the crystal nuclei. Coupled with the slow rotation speed of the stirring paddle, which is unable to disperse the aggregation between nano particles, the final product obtained is usually large particles in the micron scale.

[0005] In recent years, continuous flow reaction technologies represented by microchannel reactors have been widely used in industries such as pharmaceuticals, fine chemicals, petrochemicals, and materials due to their many advantages, including low online reaction liquid holdup, high mass and heat transfer efficiency, precise parameter control, stable process, small scale-up effect, safety and high efficiency. Since the channel size of microchannel reactors is very small, usually in the micrometer range, the resistance of the material flowing in the microchannel is very large. For rapid reactions with solid particles generated during the reaction process, once the reaction materials come into contact, a large number of large solid particles are immediately generated, which is extremely likely to cause blockage of the microchannel and render the microchannel reactor ineffective, severely limiting the application of continuous flow reaction technologies in the preparation of nano-sized powder materials. Summary of the Invention

[0006] Aiming at the above technical problems, the present invention discloses a continuous flow preparation device and a preparation method for micro-nano powder materials, which can effectively solve the problems of the inability to prepare nano-sized powders in a batch reactor and the blockage of microchannel reactors, and are particularly suitable for wet chemical reactions with fast reaction rates and the generation of solid particles, and are suitable for industrial production.

[0007] For this, the technical solution adopted by the present invention is as follows:

[0008] A continuous flow preparation device for micro-nano powder materials, which includes an ultrasonic process intensification continuous flow reactor. The ultrasonic process intensification continuous flow reactor includes a first liquid inlet, a second liquid inlet, a shunt mixing unit, and an ultrasonic intensification reaction unit. The shunt mixing unit includes a first liquid separation module, a second liquid separation module, and a mixing chamber for dividing the liquid into several streams. The inlet of the first liquid separation module is connected to the first liquid inlet, the inlet of the second liquid separation module is connected to the second liquid inlet. The first liquid separation module includes several first liquid separation channels, the second liquid separation module includes several second liquid separation channels, and the first liquid separation channels and the second liquid separation channels are arranged alternately at intervals, so that the various branches of the liquid entering through the first liquid inlet come into contact with the various branches of the liquid entering through the second liquid inlet and then enter the mixing chamber. The ultrasonic intensification reaction unit includes a reaction pipeline, the outlet of the mixing chamber is connected to the inlet of the reaction pipeline, and ultrasonic vibrators are installed on the upper and lower surfaces of the reaction pipeline, and the ultrasonic vibrators are connected to an ultrasonic generator.

[0009] Adopting this technical solution completely avoids the problem of coexistence of multiple phenomena (formation of new crystal nuclei, growth of existing crystal nuclei, aggregation of nano-particles, etc.) in the physical space of the same reaction kettle due to the mismatch between the mass transfer rate and the reaction rate in a single reaction kettle, thus completely avoiding the problems of large particle size, wide size distribution, irregular morphology, and serious aggregation existing in the preparation of nano-materials in a single reaction kettle.

[0010] As a further improvement of the present invention, the number of the second liquid separation channels is one more than that of the first liquid separation channels, and the second liquid separation channels are located outside the first liquid separation channels. With this technical solution, the tributaries passing through the first liquid separation channels are wrapped by the tributaries passing through the second liquid separation channels, and the reaction liquid passing through the second liquid separation channels flows along the inner wall of the pipeline, and the reaction liquid in the first liquid separation channels does not contact the pipeline wall.

[0011] As a further improvement of the present invention, the flow directions of the liquids in the first liquid separation channels and the second liquid separation channels form an included angle. Further, the flow directions of the liquids in the first liquid separation channels and the second liquid separation channels are perpendicular. Further, the flow directions of the liquids at the inlets of the first liquid separation module and the second liquid separation module are perpendicular. With this technical solution, the two liquids in the first liquid separation channels and the second liquid separation channels are mixed with different flow directions at different angles, and the mixing is more sufficient.

[0012] As a further improvement of the present invention, the first liquid separation channels and the second liquid separation channels are arranged alternately and spaced apart laterally, and the longitudinal dimension of the second liquid separation channels is greater than that of the first liquid separation channels. With this technical solution, the longitudinal dimension of the tributaries of the second reaction liquid in the second liquid separation channels is greater than that of the tributaries of the first reaction liquid in the first liquid separation channels. When multiple strands of reaction liquids arranged alternately and spaced apart flow synchronously into the pipeline of the mixing chamber, the tributaries of the first reaction liquid are wrapped by the tributaries of the second reaction liquid, and the tributaries of the second reaction liquid flow along the inner wall of the pipeline, and the tributaries of the first reaction liquid wrapped in the tributaries of the second reaction liquid do not contact the pipeline wall. Further preferably, the flow rate difference between the two reaction liquids can be controlled within 10-200%. In this way, micro-mixing caused by the flow rate difference will occur at the contact interface of the two reaction liquids. At the same time, since only the tributaries of the second reaction liquid flow along the inner wall of the pipeline and no solid particles are generated, the phenomenon of solid particle adhesion and pipeline blockage is fundamentally avoided.

[0013] As a further improvement of the present invention, the reaction pipeline is located in a constant temperature water bath, or the reaction pipeline is connected to a constant temperature water system. Further, the temperature control range of the constant temperature water system is -20 to 90 °C, and the temperature control accuracy is ±0.5 °C. With this technical solution, the consistency and stability of the reaction are better.

[0014] As a further improvement of the present invention, the reaction pipeline is a flat elliptical pipeline, and the ultrasonic vibrators are symmetrically arranged on the upper and lower planes of the reaction pipeline.

[0015] As a further improvement of the present invention, the number of the first liquid separation channels and the second liquid separation channels is 3 to 100, that is, the first liquid separation module and the second liquid separation module can divide the reaction liquid into 3 to 100 strands of tributaries.

[0016] As a further improvement of the present invention, the first liquid inlet is connected to a first conveying system, the second liquid inlet is connected to a second conveying system, and the first conveying system and the second conveying system respectively control the flow rates of the reaction liquids entering the first liquid inlet and the second liquid inlet, so that the flow rate difference between the two reaction liquids is 10-200%.

[0017] As a further improvement of the present invention, the outlet of the reaction pipeline is connected to a product storage container through a product pumping pump. The first conveying system includes a first conveying pump, the second conveying system includes a second conveying pump, and the flow rate of the product pumping pump is 1.02-1.10 times the total flow rate of the first conveying pump and the second conveying pump. With this technical solution, it is ensured that there will be no liquid retention and fluid dead ends in the ultrasonic process intensified continuous flow reactor, that is, it ensures the smooth flow of the reacted products and their timely discharge from the ultrasonic process intensified continuous flow reactor, and can effectively avoid the occurrence of blockage of the ultrasonic process intensified continuous flow reactor caused by liquid retention.

[0018] As a further improvement of the present invention, a stirrer is provided in the product storage container.

[0019] The present invention also discloses a continuous flow preparation method of micro-nano powder materials, which is prepared by using the continuous flow preparation device of micro-nano powder materials as described above, and includes the following steps:

[0020] Step S1, respectively conveying two reaction liquids to the first liquid inlet and the second liquid inlet through the first conveying pump and the second conveying pump, and respectively dividing them into several branches through the first liquid separation module and the second liquid separation module and then mixing them to obtain a mixed liquid;

[0021] Step S2, enabling the mixed liquid to enter the ultrasonic intensification reaction unit, and rapidly reacting under the conditions of a constant temperature water bath and the action of ultrasonic waves to generate micro-nano solid particles;

[0022] Step S3, synchronously starting the product pumping pump, pumping the suspension prepared from the ultrasonic intensification reaction unit into the product storage container, and further reacting at a set temperature and stirring speed, and then obtaining the micro-nano powder after filtration, washing and drying.

[0023] As a further improvement of the present invention, in step S1, the reactants are respectively dissolved and heated to prepare two reaction liquids, and the two reaction liquids are respectively stored in corresponding storage barrels, and the heating temperature is -20-90°C;

[0024] In step S1, the pressures of the first conveying pump and the second conveying pump for conveying the reaction liquid are 0.3-2.0 MPa, and the conveying flow rate of the reaction liquid is 5-500 L / min; the flow rate difference between the reaction liquids conveyed by the first conveying pump and the second conveying pump is 10-200%;

[0025] In step S2, the frequency of the ultrasonic wave of the ultrasonic enhanced reaction unit is 20 - 100 KHz, and the power density of the ultrasonic wave is 0.5 - 5 W / cm 2 ; The constant temperature water bath condition is -20 - 90 °C;

[0026] In step S3, the flow rate of the product pumping pump is 10 - 1000 L / min.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] First, the technical solution of the present invention utilizes the combination of the shunt mixing unit and the ultrasonic enhanced reaction unit to respectively achieve the shunt, spaced arrangement and preliminary mixing of the two reaction liquids in the shunt mixing unit, and rapidly achieve the atomic-level mixing of the two reaction liquids and the generation of nanoparticles in the ultrasonic enhanced reaction unit, effectively realizing the spatial separation of mass transfer mixing and rapid reaction, meeting both the rapid mass transfer requirements for rapid reaction and realizing continuous reaction operation, and the prepared nano-powders have good stability and consistency.

[0029] Second, the technical solution of the present invention comprehensively utilizes the shunt of the shunt mixing unit to achieve the spaced arrangement of multiple branches of the two reaction liquids, increasing the contact area between the two reaction liquids; further, a flow velocity difference between the two reaction liquids can be created, and the preliminary mixing of the two reaction liquids is achieved by using the flow velocity difference, further greatly shortening the mass transfer distance between the two reaction liquids, laying a foundation for the next-step ultrasonic perturbation to rapidly achieve atomic-level uniform mixing.

[0030] Third, the technical solution of the present invention comprehensively utilizes the shunt arrangement of the shunt mixing unit and the ultrasonic action of the ultrasonic enhanced reaction unit to completely avoid the problem of blockage of the reaction pipeline. The two liquids entering the shunt mixing unit flow through different flow channels respectively before flowing out of the shunt module and do not come into contact, so there is no problem of solid particle generation and pipeline blockage. The two liquids flowing into the mixing chamber pipeline from the liquid separation module in a spaced arrangement have a preliminary mixing. Even if solid particles are generated at the contact interface of the two reaction liquids, they are wrapped in the fluid far from the inner wall of the pipeline, and there will be no phenomenon of solid particle generation blocking the pipeline.

[0031] Fourth, in the ultrasonic process intensification continuous flow reactor of the technical solution of the present invention, there is a delivery pump in front and a pumping pump behind, and the flow rate of the pumping pump is greater than the total flow rate of the two delivery pumps, which ensures that there is no liquid retention and fluid dead angle in the process intensification continuous flow reactor, that is, it ensures the smooth flow of the reacted product and its timely discharge from the process intensification continuous flow reactor, and can effectively avoid the occurrence of the blockage phenomenon of the process intensification continuous flow reactor caused by liquid retention. Description of the Drawings

[0032] Figure 1 It is a schematic structural diagram of a continuous flow preparation device for nano powder in Embodiment 1 of the present invention.

[0033] Figure 2 It is a schematic structural diagram of a process intensification continuous flow reactor structure diagram in Embodiment 1 of the present invention.

[0034] Figure 3 It is a schematic structural diagram of a shunt mixing chamber in Embodiment 1 of the present invention.

[0035] Figure 4 It is a schematic layout structural diagram of the first liquid separation module and the second liquid separation module in Embodiment 1 of the present invention.

[0036] Figure 5 It is a simulation diagram of the flow of liquid in the ultrasonic process intensification continuous flow reactor in Embodiment 1 of the present invention.

[0037] Figure 6 It is an SEM diagram of nano magnesium hydroxide prepared in Embodiment 2 of the present invention.

[0038] Figure 7 It is an SEM diagram of nano silicon dioxide microspheres prepared in Embodiment 3 of the present invention.

[0039] Figure 8 It is an SEM diagram of nano iron phosphate prepared in Embodiment 4 of the present invention.

[0040] Reference numerals include:

[0041] 1 - Ultrasonic process intensification continuous flow reactor, 2 - Constant temperature water system, 3 - First conveying system, 4 - Second conveying system, 5 - Suction pump; 11 - First liquid inlet, 12 - Second liquid inlet, 13 - First liquid separation module, 14 - Second liquid separation module, 15 - Mixing chamber, 131 - First liquid separation channel, 132 - Liquid inlet channel, 141 - Second liquid separation channel, 16 - Ultrasonic intensification reaction chamber, 17 - Liquid outlet. Detailed implementation manners

[0042] The following further elaborates on the preferred embodiments of the present invention.

[0043] Embodiment 1

[0044] As Figure 1 shown, a continuous flow preparation device for nano powder includes an ultrasonic process intensification continuous flow reactor 1 and a constant temperature water system 2, and also includes a first conveying system 3, a second conveying system 4 for conveying reaction liquid, and a product conveying pump that are matched with it. The constant temperature water system 2 is used to maintain the temperature of the ultrasonic process intensification continuous flow reactor 1 constant.

[0045] As Figures 2 to 5As shown, the ultrasonic process intensification continuous flow reactor 1 includes a first liquid inlet 11, a second liquid inlet 12, a shunt mixing chamber, an ultrasonic intensification reaction chamber 16 and a liquid outlet 17. The shunt mixing chamber includes a first liquid separation module 13, a second liquid separation module 14 and a mixing chamber 15 for dividing the liquid into several streams. The inlet of the first liquid separation module 13 is communicated with the first liquid inlet 11, and the inlet of the second liquid separation module 14 is communicated with the second liquid inlet 12. The first liquid separation module 13 includes a number of first liquid separation channels 131 extending longitudinally and arranged side by side in the transverse direction. The second liquid separation module 14 includes a number of second liquid separation channels 141 extending longitudinally and arranged side by side. The first liquid separation channels 131 and the second liquid separation channels 141 are arranged alternately at intervals, so that the branches of the liquid entering through the first liquid inlet 11 come into contact with the branches of the liquid entering through the second liquid inlet 12 and then enter the mixing chamber 15. The ultrasonic intensification reaction chamber 16 includes a reaction pipeline. The outlet of the mixing chamber 15 is communicated with the inlet of the reaction pipeline. Ultrasonic vibrators are installed on the upper and lower surfaces of the reaction pipeline, and the ultrasonic vibrators are connected to an ultrasonic generator. Further preferably, the reaction pipeline is a flat elliptical pipeline, and the ultrasonic vibrators are symmetrically arranged on the upper and lower planes of the reaction pipeline. The reaction pipeline is connected to a constant temperature water system 2.

[0046] Further preferably, the liquid flow directions of the first liquid inlet 11 and the second liquid inlet 12 are perpendicular. The two reaction liquids enter the shunt mixing chamber vertically from the first liquid inlet 11 and the second liquid inlet 12 respectively. Specifically, the first reaction liquid enters from the first liquid inlet 11 and enters the first liquid separation module 13 through the liquid inlet channel 132. The second reaction liquid enters the second liquid separation module 14 through the second liquid inlet 12. The two reaction liquids are respectively separated and mixed through their respective liquid separation modules and then enter the mixing chamber 15. Among them, the number of the second liquid separation channels 141 is one more than the number of the first liquid separation channels 131. The second liquid separation channels 141 are located outside the first liquid separation channels 131, and the longitudinal dimension of the second liquid separation channels 141 is larger than the longitudinal dimension of the first liquid separation channels 131.

[0047] Figure 3 and Figure 4An example is given where the number of the first liquid separation channels 131 is 3 and the number of the second liquid separation channels 141 is 4. In fact, the number of the first liquid separation channels 131 and the second liquid separation channels 141 here can be multiple, and the user can set them according to needs. The first reaction liquid entering from the first liquid inlet 11 is divided into 3 tributaries after entering the first liquid separation module 13. The second reaction liquid flowing in from the second liquid inlet 12 is divided into 4 tributaries by the second liquid separation module 14. The multiple tributaries of the two reaction liquids are arranged alternately at intervals. Further preferably, the longitudinal dimension of the tributary of the second reaction liquid is greater than that of the tributary of the first reaction liquid. When the multiple reaction liquids arranged alternately at intervals flow synchronously into the pipeline of the mixing chamber 15, the tributary of the first reaction liquid is wrapped by the tributary of the second reaction liquid, and the second reaction liquid flows along the inner wall of the pipeline. The first reaction liquid wrapped in the second reaction liquid does not contact the pipeline wall. At the same time, the flow rate difference between the two reaction liquids can be controlled, such as 10-200%. In this way, micro-mixing caused by the flow rate difference will occur at the contact interface of the two reaction liquids. Further, in this embodiment, since only the second reaction liquid flows along the inner wall of the pipeline and no solid particles are generated, the occurrence of the phenomenon of solid particle adhesion and pipeline blockage is better avoided.

[0048] The temperature control range of the constant temperature water system 2 is -20 to 90 °C, and the temperature control accuracy is ±0.5 °C.

[0049] The first delivery system 3 and the second delivery system 4 both include a delivery pump, a flow meter, a pressure gauge, a pressure relief valve, a ball valve, a needle valve, etc. The front end of the first delivery system 3 is connected to the first liquid storage barrel, and the rear end is connected to the first liquid inlet 11 of the ultrasonic process intensification continuous flow reactor 1. The front end of the second delivery system 4 is connected to the second liquid storage barrel, and the rear end is connected to the second liquid inlet 12 of the ultrasonic process intensification continuous flow reactor 1, and can deliver the reaction feed liquid to the ultrasonic process intensification continuous flow reactor 1 with constant flow and constant pressure.

[0050] After the two reaction liquids are preliminarily mixed in the mixing chamber 15, they flow out from the liquid outlet 17 and enter the reaction pipeline of the ultrasonic intensification reaction chamber 16. When the preliminarily mixed solution with multiple tributaries arranged alternately at intervals flowing out from the shunt mixing chamber flows through the reaction pipeline, under the strong mechanical micro-perturbation mixing action of ultrasonic waves, atomic-level mass transfer mixing and rapid reaction to generate micro-nano particles are quickly achieved. At the same time, the strong cavitation effect of ultrasonic waves can also effectively avoid the agglomeration of solid particles and prevent the blockage of the reaction pipeline.

[0051] The micro-nano particles generated by the reaction in the ultrasonic intensification reaction chamber 16 are pumped by the pumping pump 5 and discharged from the liquid outlet 17 into the product storage tank, and then are subjected to solid-liquid separation, washing, and drying to obtain the micro-nano powder. Among them, the flow rate of the pumping pump 5 is 1.02-1.10 times the total flow rate of all the delivery pumps.

[0052] The above embodiments utilize the combination of a shunt mixing chamber and an ultrasonic intensification chamber to achieve the shunting, spaced arrangement, and preliminary mixing of two reaction liquids in the shunt mixing chamber respectively, and rapidly achieve the atomic-level mixing of the two reaction liquids and the generation of nanoparticles in the ultrasonic intensification chamber, effectively realizing the spatial separation of mass transfer mixing and rapid reaction. It not only meets the rapid mass transfer requirements for rapid reaction but also realizes continuous reaction operation, which is conducive to preparing nano-powders with good stability and consistency. Adopting the technical solution of the present invention can completely avoid the problem that a single reaction kettle has coexistence of multiple phenomena (such as the generation of new crystal nuclei, the growth of existing crystal nuclei, nanoparticle aggregation, etc.) in the physical space of the same reaction kettle due to the mismatch between the mass transfer rate and the reaction rate, thus completely avoiding the problems of large particle size, wide size distribution, irregular morphology, and serious aggregation existing in the preparation of nano-materials by a single reaction kettle.

[0053] Particularly, the above embodiments comprehensively utilize the shunting of the shunt mixing chamber to achieve the spaced arrangement of multiple branches of the two reaction liquids, increasing the contact area between the two reaction liquids; moreover, a flow velocity difference between the two reaction liquids is created, and the preliminary mixing of the two reaction liquids is realized by using the flow velocity difference, further greatly shortening the mass transfer distance between the two reaction liquids and laying a foundation for the rapid realization of atomic-level uniform mixing by ultrasonic perturbation in the next step.

[0054] More particularly, the above embodiments comprehensively utilize the shunt arrangement of the shunt mixing chamber and the ultrasonic action of the ultrasonic intensification chamber to completely avoid the problem of blockage of the reaction pipeline. The two liquids entering the shunt mixing chamber flow in different flow channels respectively before flowing out of the shunt module and do not come into contact, so there is no problem of solid particle generation and pipeline blockage. The two liquids flowing into the mixing chamber pipeline from the shunt module in a spaced arrangement are preliminarily mixed under the perturbation of the flow velocity difference. Even if solid particles are generated at the contact interface of the two reaction liquids, they are wrapped in the fluid far from the inner wall of the pipeline, and only one kind of liquid is always in contact with the inner wall of the mixing chamber pipeline, and there will be no phenomenon of solid particle generation and pipeline blockage.

[0055] More particularly, the above embodiments adopt a method in which there is a delivery pump before the process intensification continuous flow reactor and a suction pump after it, and the flow rate of the suction pump is greater than the total flow rate of the two delivery pumps, ensuring that there is no liquid retention and fluid dead angle in the process intensification continuous flow reactor, that is, ensuring the smooth flow of the reacted products and their timely discharge from the process intensification continuous flow reactor, and effectively avoiding the occurrence of blockage of the process intensification continuous flow reactor caused by liquid retention.

[0056] In addition, the above embodiments comprehensively adopt the methods of spatial separation (shunt mixing chamber and ultrasonic intensification chamber) and time continuity. It not only solves the problem of amplification effect caused by the mismatch between the three transfer rates and the reaction rate by relying on spatial separation, but also realizes the scale preparation of micro-nano powders by continuous flow mode through time continuous accumulation.

[0057] Using the above-mentioned continuous flow preparation device for nano-powders to prepare micro-nano powder materials by wet chemical method, the following steps are included:

[0058] Step S1, the reaction solutions prepared by dissolving the reactants respectively and heating them to the set temperature are stored in the corresponding storage barrels respectively. The temperature range of the heating is -20~90°C.

[0059] Step S2, the first material conveying system, the second conveying system, the heater of the constant temperature water system, the ultrasonic generator, and the product conveying pump are respectively turned on, and parameters such as the pressure and flow rate of the material conveying system, the frequency and power density of the ultrasonic wave, the temperature of the constant temperature water system, and the flow rate of the product conveying pump are set. The conveying pressure range of the first conveying system and the second conveying system is 0.3~2.0MPa, and the material conveying flow rate is 5~500L / min. The frequency of the ultrasonic wave is 20~100KHz, and the power density of the ultrasonic wave is 0.5~5W / cm 2 . The temperature range of the constant temperature water system is -20~90°C. The flow rate of the product conveying pump is 10~1000L / min.

[0060] Step S3, the conveying pumps of the first conveying system and the second conveying system are turned on to pump the reaction solutions into the ultrasonic process intensifying continuous flow reactor. At the same time, the liquid pressure of the conveying pipeline is adjusted to the set value by adjusting the ball valve and the needle valve, so that the two reaction solutions are shunted through the shunt mixing chamber at a constant pressure and constant flow rate and flow into the ultrasonic intensifying reaction chamber in an alternating and spaced arrangement, and quickly react to generate micro-nano solid particles under the cavitation effects such as mass transfer intensification, reaction, and crystallization of the ultrasonic wave.

[0061] Step S4, the product pumping and conveying pump is synchronously turned on to pump the suspension prepared from the ultrasonic process intensifying continuous flow reactor into the product storage barrel, and further react for a period of time at the set temperature and stirring speed. The prepared micro-nano particles are then filtered, washed, and dried to obtain micro-nano powders.

[0062] The following is illustrated with specific examples.

[0063] Example 2 Preparation of nano magnesium hydroxide

[0064] Step S1, an aqueous solution of magnesium chloride with a molar concentration of 0.65mol / L and an aqueous solution of sodium hydroxide with a molar concentration of 2.0mol / L are respectively prepared, and the two solutions are heated to 60°C and stored in the corresponding storage barrels respectively.

[0065] Step S2, turn on the first conveying system, the second conveying system, the heater of the constant temperature water system, the ultrasonic process intensification continuous flow reactor, and the product delivery pump respectively. Set the pressure and flow rate of the material conveying system, adjust the pressures of the two reaction liquid conveying systems to 1.2 MPa, pump the sodium hydroxide aqueous solution into the ultrasonic process intensification continuous flow reactor from the first liquid inlet at a flow rate of 25 L / min, and pump the magnesium chloride aqueous solution into the ultrasonic process intensification continuous flow reactor from the second liquid inlet at a flow rate of 38.5 L / min, and set the ultrasonic frequency and power density, where the frequency is 20 KHz and the power density is 3.5 W / cm 2 , set the temperature of the constant temperature water system to 60 °C, and set the flow rate of the product delivery pump to 67 L / min.

[0066] Step S3, turn on the material delivery pump to pump the reaction liquid into the ultrasonic process intensification continuous flow reactor. At the same time, adjust the ball valve and needle valve to make the liquid pressure in the conveying pipeline reach the set value of 1.2 MPa, so that the two reaction liquids are shunted through the shunt mixing chamber and flow into the ultrasonic intensification chamber at intervals and alternately. Under the cavitation effects such as enhanced mass transfer, reaction, and crystallization of ultrasonic waves, they quickly react to form nano magnesium hydroxide particles.

[0067] Step S4, synchronously turn on the product pumping and delivery pump, pump the suspension prepared from the ultrasonic process intensification continuous flow reactor into the product storage bucket, and further stir and age at 60 °C for 4 hours. The prepared nano magnesium hydroxide is filtered, washed, and dried to obtain a dry powder. The scanning electron microscope photograph of the prepared nano magnesium hydroxide is as Figure 6 shown. It can be seen that the obtained nano magnesium hydroxide particles have small particle sizes, uniform sizes, and no agglomeration phenomenon.

[0068] Example 3 Nano silicon oxide microspheres

[0069] Based on Example 1, the steps of this example are as follows:

[0070] Step S1, mix absolute ethanol and tetraethyl orthosilicate in a volume ratio of 3.9:1 to prepare a first reaction liquid, mix absolute ethanol, 25% ammonia water, and pure water in a volume ratio of 15.7:1.4:1 to prepare a second reaction liquid, and heat both the first reaction liquid and the second reaction liquid to 40 °C and store them in the corresponding storage buckets respectively.

[0071] Step S2, turn on the controllers of the material conveying system, the heater of the constant temperature water system, the ultrasonic process intensification continuous flow reaction system, and the product delivery pump respectively. Set the pressure and flow rate of the material conveying system, adjust the pressures of the two reaction liquid conveying systems to 0.4 MPa, pump the first reaction liquid into the ultrasonic process intensification continuous flow reactor at a flow rate of 100 L / min from the first liquid inlet, and pump the second reaction liquid into the reactor at a flow rate of 194 L / min from the second liquid inlet simultaneously. Set the ultrasonic frequency and power density, with the frequency being 28 KHz and the power density being 2.5 W / cm 2 , and the temperature of the constant temperature water system is 40 °C. Set the flow rate of the product delivery pump to 310 L / min.

[0072] Step S3, turn on the material delivery pump to pump the reaction liquid into the ultrasonic process intensification continuous flow reactor. At the same time, adjust the ball valve and needle valve to make the liquid pressure in the delivery pipeline reach the set value of 0.4 MPa, so that the two reaction liquids are shunted through the shunt mixing chamber at a constant pressure and constant flow rate and flow into the ultrasonic intensification chamber in an alternating and spaced arrangement. Under the cavitation effects of ultrasonic enhanced mass transfer, reaction, crystallization, etc., they quickly react to form nano magnesium hydroxide particles.

[0073] Step S4, synchronously turn on the product pumping and delivery pump, pump the suspension obtained from the ultrasonic process intensification continuous flow reactor into the product storage bucket, and further stir and age at 40 °C for 6 hours. The prepared nano silica particles are obtained as dry powder after filtration, washing, and drying. The scanning electron microscope photo of the prepared nano silica is as Figure 7 shown. It can be seen that the obtained nano silica microspheres have small size, narrow size distribution, are uniform, have good consistency, and no agglomeration phenomenon is observed.

[0074] Example 4 Preparation of Nano Iron Phosphate

[0075] Step S1, add ferrous sulfate, hydrogen peroxide, and sulfuric acid step by step to pure water according to a molar ratio of 2:1:1, and stir and react to prepare a first reaction liquid with a molar concentration of Fe 3+ of 1.0 mol / L. Dissolve phosphoric acid and sodium hydroxide in pure water according to a molar ratio of 1:2.2 to prepare a second reaction liquid with a phosphoric acid molar concentration of 0.8 mol / L. Heat the two solutions to 70 °C and store them in the corresponding storage buckets respectively.

[0076] Step S2, turn on the controllers of the material conveying system, the heater of the constant temperature water system, the ultrasonic process intensification continuous flow reaction system, and the product delivery pump respectively. Set the pressure and flow rate of the material conveying system, adjust the pressures of the two reaction liquid conveying systems to 1.0 MPa, pump the first reaction liquid into the ultrasonic process intensification continuous flow reactor at a flow rate of 160 L / min from the first liquid inlet, and pump the second reaction liquid into the reactor at a flow rate of 200 L / min from the second liquid inlet simultaneously. Set the ultrasonic frequency and power density, with the frequency being 40 KHz and the power density being 4.0 W / cm 2 , the temperature of the constant temperature water system is 70 °C, and set the flow rate of the product delivery pump to 380 L / min.

[0077] Step S3, turn on the material delivery pump to pump the reaction liquid into the ultrasonic process intensification continuous flow reactor. At the same time, adjust the ball valve and needle valve to make the liquid pressure in the delivery pipeline reach the set value of 1.0 MPa, so that the two reaction liquids are shunted through the shunt mixing chamber and flow into the ultrasonic intensification chamber in an alternating and spaced arrangement. Under the cavitation effects of ultrasonic enhanced mass transfer, reaction, crystallization, etc., they quickly react to form nano magnesium hydroxide particles.

[0078] Step S4, synchronously turn on the product pumping and delivery pump, pump the suspension obtained from the ultrasonic process intensification continuous flow reactor into the product storage bucket, and further stir and age at 70 °C for 8 hours. The prepared nano iron phosphate is obtained as a dry powder after filtration, washing, and drying. The following figure shows the scanning electron microscope photograph of the prepared nano iron phosphate as Figure 8 shown. It can be seen that the obtained nano iron phosphate particles have small particle sizes, uniform sizes, and good consistency.

[0079] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A continuous flow preparation device for micro-nano powder materials, characterized in that: It includes an ultrasonic process intensification continuous flow reactor, and the ultrasonic process intensification continuous flow reactor includes a first liquid inlet, a second liquid inlet, a shunt mixing unit and an ultrasonic intensification reaction unit. The shunt mixing unit includes a first liquid separation module, a second liquid separation module and a mixing chamber for dividing the liquid into several streams. The inlet of the first liquid separation module is communicated with the first liquid inlet, the inlet of the second liquid separation module is communicated with the second liquid inlet. The first liquid separation module includes several first liquid separation channels, the second liquid separation module includes several second liquid separation channels, and the first liquid separation channels and the second liquid separation channels are arranged alternately at intervals, so that the branches of the liquid entering through the first liquid inlet come into contact with the branches of the liquid entering through the second liquid inlet and then enter the mixing chamber; the ultrasonic intensification reaction unit includes a reaction pipeline, the outlet of the mixing chamber is communicated with the inlet of the reaction pipeline, ultrasonic oscillators are installed on the upper and lower surfaces of the reaction pipeline, and the ultrasonic oscillators are connected with an ultrasonic generator; The number of the second liquid separation channels is one more than that of the first liquid separation channels, and the second liquid separation channels are located outside the first liquid separation channels.

2. The continuous flow preparation device for micro-nano powder materials according to claim 1, characterized in that: The flow directions of the liquid in the first liquid separation channels and the second liquid separation channels form an included angle.

3. The continuous flow preparation device for micro-nano powder materials according to claim 2, wherein: The flow directions of the liquid in the first liquid separation channels and the second liquid separation channels are perpendicular.

4. The continuous flow preparation device for micro-nano powder materials according to claim 1, characterized in that: The first liquid separation channels and the second liquid separation channels are arranged alternately at intervals in the horizontal direction, and the longitudinal dimension of the second liquid separation channels is greater than that of the first liquid separation channels.

5. The continuous flow preparation device for micro-nano powder materials according to claim 1, characterized in that: The reaction pipeline is located in a constant temperature water bath tank, or the reaction pipeline is connected with a constant temperature water system.

6. The continuous flow preparation device for micro-nano powder materials according to claim 5, characterized in that: The first liquid inlet is connected with a first conveying system, the second liquid inlet is connected with a second conveying system, and the first conveying system and the second conveying system respectively control the flow rates of the reaction liquids entering through the first liquid inlet and the second liquid inlet, so that the flow rate difference between the two reaction liquids is 10-200%.

7. The continuous flow preparation device for micro-nano powder materials according to claim 6, characterized in that: The outlet of the reaction pipeline is connected to a product storage container through a product pumping pump. The first conveying system includes a first conveying pump, the second conveying system includes a second conveying pump, and the flow rate of the product pumping pump is 1.02-1.10 times the total flow rate of the first conveying pump and the second conveying pump.

8. A continuous flow preparation method for micro-nano powder materials, characterized in that: Prepared by using the continuous flow preparation device for micro-nano powder materials as described in claim 7, including the following steps: Step S1, respectively conveying two reaction liquids to the first liquid inlet and the second liquid inlet through the first conveying pump and the second conveying pump, dividing them into several branches through the first liquid separation module and the second liquid separation module respectively and then mixing them to obtain a mixed liquid; Step S2, enabling the mixed liquid to enter the ultrasonic intensification reaction unit, and rapidly reacting under the conditions of constant temperature water bath and ultrasonic waves to generate micro-nano solid particles; Step S3, pumping the suspension prepared from the ultrasonic intensification reaction unit to the product storage container through the product pumping pump, and further continuously reacting at a set temperature and stirring speed, and then obtaining micro-nano powder after filtration, washing and drying.

9. The continuous flow preparation method of the micro-nano powder material according to claim 8, characterized in that: In step S1, the reactants are respectively dissolved and heated to prepare two reaction liquids, and the two reaction liquids are respectively stored in corresponding storage barrels, and the heating temperature is -20-90°C; In step S1, the pressures of the first transfer pump and the second transfer pump for transferring the reaction liquid are 0.3 to 2.0 MPa, and the transfer flow rate of the reaction liquid is 5 to 500 L / min; the flow velocity difference of the reaction liquid transferred by the first transfer pump and the second transfer pump is 10 to 200%; In step S2, the frequency of the ultrasonic wave of the ultrasonic enhanced reaction unit is 20 to 100 KHz, and the power density of the ultrasonic wave is 0.5 to 5 W / cm 2 ; The constant temperature water bath condition is -20 to 90 °C; In step S3, the flow rate of the product pumping pump is 10 to 1000 L / min.

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