Fluidization coating device with pulse, stirring and double-particle triple synergy

Abstract

The invention relates to the technical field of fluidized beds, in particular to a fluidization coating device with pulse, stirring and double-particle triple synergy, which comprises a spray fluidized bed reactor, a fluidized bed reactor, a stirring device and a double-particle fluidized bed reactor, the gas distributor is positioned above the carrier gas inlet and is used for uniformly distributing carrier gas entering from the carrier gas inlet on the whole bed layer to form fluidized gas; the gas-liquid two-phase flow nozzle is connected with the gas supply unit and the coating liquid conveying tank and is used for atomizing the coating liquid into micron-sized small liquid drops and then spraying the micron-sized small liquid drops into the spray fluidized bed reactor; the mechanical shearing unit continuously generates local mechanical crushing on the aggregate; the pulse air inlet device is connected with the air supply unit and is used for applying periodic pulse airflow to the fluidized bed layer and breaking particle aggregation and channeling formed during initial fluidization; and the flow aiding particles and the fine powder particles to be coated jointly form a double-particle fluidization system. The problems of difficult fluidization starting, non-uniform fluidization and the like of ultrafine powder particles are solved through triple synergy of pulse, stirring and double particles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluidized bed, and particularly relates to a fluidized coating device with pulse, stirring and double-particle triple synergy. BACKGROUND

[0002] Fluidized bed spray coating technology is one of the core processes for surface functionalization and modification of powder materials, and is widely used in the fields of pharmaceuticals, food, chemical industry and new energy materials. The basic principle is to make solid particles in a fluidized state by airflow, and to atomize and spray coating liquid into the bed. The droplets spread on the surface of the particles and form a uniform coating film after drying, thereby giving the particles sustained-release, taste masking, moisture-proof, stability or specific chemical properties.

[0003] However, with the increasing degree of product refinement, especially when dealing with ultra-fine powder particles with small particle size (usually less than 50 microns), high surface energy and easy agglomeration, the traditional fluidized bed coating technology faces serious challenges in the basic principles, mainly in the following technical bottlenecks: First, the fluidization is difficult to start and uniformize. The strong van der Waals force between ultra-fine powder particles leads to serious agglomeration in the initial stage, forming a "dead bed" that is difficult to fluidize. The traditional continuous stable airflow is difficult to provide enough shear force to break up these initial agglomerates, and is easy to form channeling and bubbles in the bed, resulting in uneven gas distribution. Although the introduction of a single pulse airflow can produce macroscopic disturbance to the fluidized bed, improve the spatial uniformity, but it has limited effect on the bottom solid static agglomerate layer, and cannot fundamentally solve the "dead bed" problem. While the mechanical stirring alone can force the bottom agglomerates to break up, the mixing effect is weakened in the upper part of the bed, and excessive shear is generated. While the simple flow-assisted particle system (adding coarse particles as medium) can improve the micro-mixing, but it is insufficient to improve the stability of the macro-fluidization state.

[0004] Secondly, in the coating process, the dynamic stability is poor, and wet agglomeration easily occurs. Even after the initial fluidization is achieved, due to the large specific surface area and high surface energy of ultra-fine powder particles, the coating liquid that is not dried in time is easy to form liquid bridges between particles during the spraying stage, inducing "wet agglomeration". Once this agglomerate is formed, the conventional fluidization airflow is difficult to break it up, leading to deterioration of the coating process, widening of the product particle size distribution, and sharp decline in uniformity. The existing technology often focuses on optimizing the atomization or drying parameters, but does not prevent the generation of wet agglomeration from the source of fluidization quality, i.e. providing a continuous and strong particle dispersion force field.

[0005] Finally, the process efficiency and the coating quality are difficult to be balanced. In order to overcome the above problems, the prior art usually adopts conservative strategies such as increasing the operation gas velocity, prolonging the coating time or reducing the spraying rate, which directly leads to the increase of energy consumption, the decrease of production efficiency, and the influence on the integrity of the coating film (such as the occurrence of cracking or "orange peel" phenomenon) due to excessive drying or local over-wetting, and finally affects the yield, performance consistency and economy of the product. SUMMARY

[0006] The purpose of the present application is to provide a fluidized coating device with pulse, stirring and double-particle triple synergy, so as to solve the problems of difficult starting of ultra-fine powder particles, uneven coating and poor product consistency.

[0007] In order to achieve the above purpose, the present application adopts the following technical scheme: a fluidized coating device with pulse, stirring and double-particle triple synergy, comprising: a spray fluidized bed reactor provided with a heating system and a carrier gas inlet; a gas distributor arranged in the spray fluidized bed reactor and located above the carrier gas inlet, for uniformly distributing the carrier gas entering the carrier gas inlet in the entire bed layer to form a fluidized gas; a gas-liquid two-phase flow nozzle arranged in the spray fluidized bed reactor and connected with a gas supply unit and a coating liquid delivery tank, for atomizing the coating liquid into micron-sized small droplets and then spraying them into the spray fluidized bed reactor; a mechanical shearing unit arranged at the bottom of the bed layer of the spray fluidized bed reactor, for continuously generating local mechanical fragmentation of the agglomerates; a pulse gas inlet device arranged on the spray fluidized bed reactor and connected with the gas supply unit, for applying a periodic pulse gas flow to the fluidized bed layer to break the particle agglomeration and channeling formed during initial fluidization; and flow-assisting particles filled in the spray fluidized bed reactor, the flow-assisting particles and the fine powder particles to be coated forming a double-particle fluidization system, for preventing the fine powder from re-agglomerating through collision and friction, the particle size of the flow-assisting particles being larger than that of the fine powder particles to be coated. The flow-assisting particles collide and rub with the fine powder particles to be coated in the bed layer, continuously breaking up the lumps of the fine powder particles to be coated, the pulse gas inlet device applies a periodic pulse gas flow to the fluidized bed layer, at the same time, the mechanical shearing unit continuously generates local mechanical fragmentation of the agglomerates, forcibly breaking up the dead zones and lumps at the bottom of the bed layer, the synergistic cooperation between the pulse gas flow, the mechanical shearing unit and the double-particle fluidization system composed of the flow-assisting particles and the fine powder particles to be coated, together overcome the initial agglomeration force of the ultra-fine powder particles, realize the forced starting from static agglomeration to uniform fluidization, and make the bed layer reach a uniform and stable fluidization state.

[0008] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein the spray fluidized bed reactor comprises: a cylindrical reaction section, the gas distributor, the mechanical shearing unit and the pulse air inlet device are arranged at the bottom of the cylindrical reaction section; a conical sedimentation section is arranged at the bottom of the cylindrical reaction section and communicates with the cylindrical reaction section, the conical sedimentation section expands upward in diameter, and the gas-liquid two-phase flow nozzle is arranged at the conical sedimentation section.

[0009] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein the volume of the flow-assisted particle material accounts for 5% to 20% of the total volume after the fine powder particles to be coated and the flow-assisted particles are mixed; the particle size of the fine powder particles to be coated ranges from 1 to 50 μm, the particle size of the flow-assisted particles ranges from 50 to 150 μm, and the particle size ratio between the flow-assisted particles and the fine powder particles to be coated is 2.5 to 5:1.

[0010] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein the gas supply unit further comprises a carrier gas source, and a pulse gas pipeline and a fluidization gas pipeline are arranged in parallel at the gas outlet of the carrier gas source, wherein: the pulse gas pipeline is connected with the pulse air inlet device, and a buffer tank and a pulse valve are arranged on the pulse gas pipeline; the fluidization gas pipeline is connected with the carrier gas inlet, a spray gas pipeline connected with the gas-liquid two-phase flow nozzle is arranged on the fluidization gas pipeline, and a mass flow meter and a control valve are arranged on the fluidization gas pipeline and the spray gas pipeline; the fluidization gas pipeline is further provided with a gas preheating device located at the front side of the spray gas pipeline.

[0011] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein the diameter ratio between the maximum diameter of the conical sedimentation section and the cylindrical reaction section is 1.2 to 1.5:1, and the height-diameter ratio of the cylindrical reaction section is 3 to 5:1.

[0012] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein the gas distributor is a sintered metal plate or a perforated plate; the mechanical shearing unit is any one or a combination of a frame stirring paddle, an anchor stirring paddle, a paddle stirring paddle or a spiral stirring paddle.

[0013] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein the flow-assisted particles are any one of alumina, silicon dioxide and zirconium oxide; the flow-assisted particles are any one of spherical, cylindrical, cubic and irregular shapes; and the carrier gas is any one of nitrogen, argon and helium.

[0014] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein an integrated material conveying system is further arranged on the spray fluidized bed reactor; the material conveying system comprises a feeding tank, a discharging tank and a collecting tank; the feeding tank is used for containing fine powder particles to be coated, an observation port and a pressure detector are arranged on the feeding tank, and a feeding pipe connected with the spray fluidized bed reactor is arranged at the bottom of the feeding tank; the discharging tank is used for temporarily storing materials, a first metal filter is arranged at the top of the discharging tank, the first metal filter is connected with an exhaust treatment system through a first exhaust pipe, a discharging pipe connected with the spray fluidized bed reactor is arranged on the discharging tank, and a collecting pipe is arranged at the bottom of the discharging pipe; and the collecting tank is used for collecting and storing materials in batches, and a detachable vibrating screen is arranged at the top of the collecting tank.

[0015] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein a second metal filter is arranged at the top of the conical sedimentation section, the second metal filter is connected with the exhaust treatment system through a second exhaust pipe, openable and closable atomizer channels are arranged at the middle and bottom of the conical sedimentation section, and a coating liquid conveying pipeline is arranged in any one of the atomizer channels.

[0016] Further, the fluidized coating device with the triple synergy of pulse, stirring and double particles, wherein the heating system is an electric resistance heating furnace, the electric resistance heating furnace is arranged in sections around the cylindrical reaction section, and each electric resistance heating furnace is independently controlled; a pressure detector and a temperature detector are arranged on the cylindrical reaction section.

[0017] The beneficial effects of the present application are as follows: (1) The fluidization starting problem of superfine powder particles is fundamentally solved: for 1-50 μm fine powder particles prone to agglomeration which cannot be handled by the traditional fluidized bed, the system can realize rapid (usually less than 30 seconds) and stable starting of fluidization, and the success rate is 100%, which lays a good foundation for subsequent coating.

[0018] (2) The uniformity of coating and the consistency of products are greatly improved: the triple synergy mechanism creates an ideal fluidization state without dead zones and without channeling, so that each fine powder particle to be coated has an equal opportunity to be coated. Experiments show that the relative standard deviation (RSD) of the content of active ingredients in the coated product can be reduced to below 3%, the uniformity of the film thickness is extremely high, and the difference between batches of products is extremely small.

[0019] (3) significantly inhibit the agglomeration phenomenon, improve the product yield: through the pulse gas for active prevention, through mechanical stirring and flow particles of dynamic crushing, effectively prevent the formation of "wet agglomeration" and dry hard agglomeration. The proportion of too large agglomerates (such as > 150 μm) in the coated product can be stably below 1%, so that the qualified product yield is significantly improved, which can reach more than 98%.

[0020] (4) realize the dual optimization of process efficiency and economic benefit: due to high fluidization quality, fast heat and mass transfer, the system can operate at lower fluidization gas speed and coating temperature, and the energy consumption is significantly reduced. At the same time, the efficient contact and drying make the utilization rate of coating liquid reach more than 95%, reducing the waste of raw materials. The overall process cycle is also shortened due to the improvement of mixing and drying efficiency.

[0021] (5) enhance the applicability and controllability of the process: the adaptability of the system to materials is wider, especially suitable for high viscosity, easy to agglomerate and difficult to handle powder. At the same time, multiple adjustable parameters such as pulse and stirring provide rich means for process optimization, which is convenient for flexible adjustment for different products and realizes precise control. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The structure diagram of the fluidized coating device with pulse, stirring and double particle triple synergy according to the application is shown. DETAILED DESCRIPTION

[0023] The fluidized coating device with pulse, stirring and double particle triple synergy according to the application will be described in detail below in combination with the drawings and preferred embodiments.

[0024] As Figure 1As shown, the fluidized coating device with pulse, stirring and double-particle triple synergy comprises a spray fluidized bed reactor 1 provided with a heating system 11 and a carrier gas inlet 12; a gas distributor 2 arranged in the spray fluidized bed reactor 1 and located above the carrier gas inlet 12, which uniformly distributes the carrier gas entering from the carrier gas inlet 12 on the entire bed layer to form a fluidized gas; a gas-liquid two-phase flow nozzle 3 located in the spray fluidized bed reactor 1, which is connected with a coating liquid delivery tank 32 through a coating liquid delivery pipeline 31, and is also connected with a gas supply unit, which is used to spray the micron-sized small droplets of the coating liquid into the spray fluidized bed reactor 1 after atomization; a mechanical shearing unit 4 arranged at the bottom of the bed layer of the spray fluidized bed reactor 1, which continuously produces local mechanical crushing of the agglomerates; a pulse gas inlet device 5 located on the spray fluidized bed reactor 1 and connected with the gas supply unit, which is used to apply a periodic pulse gas flow to the fluidized bed layer, and the pulse gas flow can effectively break the particle agglomeration and channeling formed during initial fluidization; flow-assisting particles filled in the spray fluidized bed reactor 1, which together with the fine powder particles to be coated form a double-particle fluidization system, the particle size of the flow-assisting particles is larger than that of the fine powder particles to be coated, and the collision and friction between the flow-assisting particles and the fine powder particles to be coated prevent the re-agglomeration of the fine powder particles.

[0025] The gas distributor 2 is a sintered metal plate or a perforated plate, and in the embodiment, the gas distributor 2 is preferably a sintered metal plate; the mechanical shearing unit 4 is any one or a combination of a frame stirring paddle, an anchor stirring paddle, a paddle stirring paddle or a spiral stirring paddle, and in the embodiment, the mechanical shearing unit 4 is preferably a frame stirring paddle.

[0026] The pre-added flow-assisted particles in the spray fluidized reactor 1, the heating system 11 heats the spray fluidized bed reactor 1 to a set temperature, and the fine powder particles to be coated are added into the spray fluidized bed reactor 1 to mix with the flow-assisted particles. The carrier gas enters the spray fluidized bed reactor 1 through the carrier gas inlet 12 and the gas distributor 2 to form the basic fluidization. The flow-assisted particles in the bed serve as grinding media, continuously breaking up the agglomerates of fine powder particles to be coated through collisions and friction between them. At the same time, the pulse air inlet device 5 applies a periodic pulse air flow to the fluidized bed to break the particle agglomeration and channeling formed during the initial fluidization. The mechanical shearing unit 4 continuously produces local mechanical crushing of the agglomerates, forcing the crushing of the dead zone and agglomerates at the bottom of the bed. The synergistic cooperation between the pulse air flow, the mechanical shearing unit 4 and the dual-particle fluidization system composed of flow-assisted particles and fine powder particles to be coated, together overcome the initial agglomeration force of ultra-fine powder particles, realize the forced start from static agglomeration to uniform fluidization, and make the bed reach a uniform and stable fluidization state. Subsequently, the coating liquid delivery tank 32 delivers the coating liquid to the gas-liquid two-phase flow nozzle 3 through the coating liquid delivery pipeline 31, and the gas supply unit passes the carrier gas into the gas-liquid two-phase flow nozzle 3. The coating liquid and the carrier gas are mixed in the gas-liquid two-phase flow nozzle 3, and the gas-liquid two-phase flow nozzle 3 sprays the coating liquid into micron-sized small droplets, which are sprayed out and contact, spread, dry, and finally form a coating film on the fine powder particles to be coated and the flow-assisted particles in the spray fluidized bed reactor 1.

[0027] In this embodiment, the spray fluidized bed reactor 1 includes a cylindrical reaction section 13 and a conical settling section 14 in communication. The gas distributor 2, the mechanical shearing unit 4 and the pulse air inlet device 5 are all arranged at the bottom of the cylindrical reaction section 13. The conical settling section 14 is located above the cylindrical reaction section 13 and expands in diameter upward. The gas-liquid two-phase flow nozzle 3 is located at the conical settling section 14. The diameter ratio between the maximum diameter of the conical settling section 14 and the cylindrical reaction section 13 is 1.2-1.5:1, effectively reducing the gas velocity and promoting the settlement and return of the fine powder particles to be coated. The height-diameter ratio of the cylindrical reaction section is 3-5:1, ensuring sufficient reaction residence time.

[0028] In the embodiment, the volume of the flow-aiding particles accounts for 5% to 20% of the total volume after the fine powder particles to be coated and the flow-aiding particles are mixed; the particle size of the fine powder particles to be coated ranges from 1 to 50 μm, the particle size of the flow-aiding particles ranges from 50 to 150 μm, and the particle size ratio between the flow-aiding particles and the fine powder particles to be coated is 2.5 to 5:1, the flow-aiding particles are any one of alumina, silica, and zirconia; the flow-aiding particles are any one of spherical, cylindrical, cubic, and irregular shapes; in the embodiment, the flow-aiding particles are preferably spherical alumina flow-aiding particles; for example, a certain proportion (10% by volume) of spherical alumina flow-aiding particles (100 μm in particle size) is added to the fine powder particles (30 μm in particle size) to be coated. These larger, heavier, and smoother flow-aiding particles act as "grinding media" and "flow promoters" in the bed, continuously breaking up the fine powder particle agglomerates through collision and friction, greatly improving the overall fluidization quality.

[0029] The gas supply unit comprises a carrier gas source 6, a pulse gas pipeline 61 and a fluidization gas pipeline 62 are arranged in parallel on the gas outlet of the carrier gas source 6, a spray gas pipeline 63 is arranged on the fluidization gas pipeline 62, the pulse gas pipeline 61 is connected with the pulse gas inlet device 5, the fluidization gas pipeline 62 is connected with the carrier gas inlet 12, the spray gas pipeline 63 is connected with the gas-liquid two-phase flow nozzle 3, a buffer tank 611 and a pulse valve 612 are arranged on the pulse gas pipeline 61, the pressure of the buffer tank 611 is preferably 0.4 MPa, the opening time of the pulse valve 612 is preferably 0.6 s, and the pulse frequency is preferably 0.05 Hz; a gas preheating device 621 is arranged on the fluidization gas pipeline 62, and the gas preheating device 621 is located on the front side of the spray gas pipeline 63; the arrangement of the gas preheating device 621 on the fluidization gas pipeline 62 can ensure that the gas entering the spray fluidized bed reactor 1 is at an accurate process temperature; a mass flow meter and a control valve are arranged on the fluidization gas pipeline 62 and the spray gas pipeline 63, which are not shown in the figure. The carrier gas provided by the carrier gas source 6 is any one of nitrogen, argon, and helium; in the embodiment, the carrier gas is preferably nitrogen.

[0030] In the embodiment, an integrated material conveying system is further arranged on the spray fluidized bed reactor 1; the material conveying system comprises a feeding tank 7, a discharging tank 8, and a collecting tank 9. The feeding tank 7 is used for containing the fine powder particles to be coated, and a feeding pipe 71 that is in communication with the conical sedimentation section 14 in the spray fluidized bed reactor 1 is arranged at the bottom of the feeding tank 7. The unloading tank 8 is used for temporarily storing the material. A first metal filter 81 is arranged on the top of the unloading tank 8 and connected with the tail gas treatment system 10 through a first tail gas pipe. An unloading pipe 82 is arranged on the unloading tank 8 and connected with the cylindrical reaction section 13 in the spray fluidized bed reactor 1. A material collecting pipe 83 is arranged on the bottom of the unloading tank 8. The material collecting tank 9 is used for collecting and storing the material in batches. A detachable vibrating screen is arranged on the top of the material collecting tank 9.

[0031] The fine powder particles to be coated are preloaded into the feeding tank 7 and then discharged into the conical settling section 14 of the spray fluidized bed reactor 1 through the feeding pipe 71 and then settled into the cylindrical reaction section 13 to mix with the flow-aiding particles. The coating liquid coats the fine powder particles to be coated and the flow-aiding particles to form the product and by-product. After the coating is completed, the product and by-product are discharged into the unloading tank 8 through the unloading pipe 82 for temporary storage and then discharged into the material collecting tank 9 through the material collecting pipe 83 for batch collection. During the collection, the vibrating screen is detached to filter out the by-product with large volume and only collect the product. After the collection of the product is completed, the vibrating screen is detached and sealed for storage. The continuous operation of the spray fluidized bed reactor 1 is not affected during the collection, and the efficiency is improved. When the mixture of the product and by-product is discharged into the unloading tank 8, the mixture is entrained in the gas flow. The first metal filter 81 can prevent the mixture from being entrained by the gas flow and entering the tail gas treatment system 10. The gas flow is discharged after being treated in the tail gas treatment system 10 to prevent pollution of the external environment. The feeding tank 7, the unloading tank 8 and the material collecting tank 9 can be used to add and collect the material in a closed environment, which avoids the pollution and dust leakage caused by manual operation and is particularly suitable for the pharmaceutical and high-purity material industries.

[0032] A second metal filter 141 is arranged at the top of the conical settling section 14, and is connected with the tail gas treatment system 10 through a second tail gas pipe. A pressure detector 131 is arranged on the cylindrical reaction section 13. During the coating reaction, the second metal filter 141 can prevent the fine powder particles and flow-aiding particles in the spray fluidized bed reactor 1 from being entrained into the tail gas treatment system 10 by the gas flow. The gas flow in the spray fluidized bed reactor 1 is discharged after being treated in the tail gas treatment system 10, so as to prevent pollution of the external environment. When the pressure detector 131 detects that the pressure in the spray fluidized bed reactor 1 is too high, the safety valve on the exhaust pipe 142 is opened to discharge and relieve pressure. An openable atomizer passage is arranged at the middle and bottom of the conical settling section 14. The coating liquid delivery pipeline 31 is arranged in any one of the atomizer passages. According to the material height, the coating liquid delivery pipeline 31 can be arranged in the corresponding atomizer passage, so as to adjust the height of the gas-liquid two-phase flow nozzle 3, so that the coating liquid can completely cover and penetrate the flowing material, and ensure that each fine powder particle has an equal opportunity to be coated, thereby improving the coating uniformity and consistency.

[0033] In the embodiment, the tail gas treatment system 10 comprises, in sequence, a condensation tank 101, a filter tank 102, a buffer tank 103 and a liquid seal tank 104. The condensation tank 101 is connected with the first metal filter 81 and the second metal filter 141. The high-temperature gas flow filtered through the first metal filter 81 or the second metal filter 141 is first condensed in the condensation tank 101, and then enters the filter tank 102 for further filtration, enters the buffer tank 103 for pressure stabilization, and finally enters the liquid seal tank 104 for final purification and exhaust.

[0034] The heating system 11 is an electric resistance heating furnace, which is arranged in sections around the cylindrical reaction section 13, and each electric resistance heating furnace is independently controlled. A temperature detector 132 is arranged on the cylindrical reaction section 13. The independently controlled electric resistance heating furnaces form an internal temperature control heating mode on the cylindrical reaction section 13 in cooperation with the temperature detector 132, have high heating efficiency, and are beneficial to axial high-precision temperature control of the cylindrical reaction section 13, so as to provide an ideal thermal environment for instantaneous drying and uniform film formation of the coating liquid.

[0035] Comparative Example 1 (traditional technical route) Device and process: traditional fluidized bed (no pulse, no mechanical stirring, no flow-aiding particles). Only stable fluidization gas is introduced.

[0036] Experimental process: 2 kg of spherical silica powder was added to the feeding tank. The particle size of the material was 5-10 μm, and the loose bulk density was 0.55 g / cm 3, after the feed tank is pressurized to 0.2 MPa, the feed valve is opened, the material is fed from the feed tank in a high-pressure state to the fluidized bed reactor in a normal-pressure state, then the fluidizing gas valve is opened, the size of the fluidizing gas flow is adjusted, and the fluidization state of the material is observed. It is found that when the fluidizing gas velocity reaches 0.3 m / s, the material still cannot be fluidized, and the experiment ends in failure. After the fluidized bed reactor is pressurized, the material is pressed into the unloading tank in a normal-pressure state.

[0037] Comparative Example 2 (single pulse improvement) Device and process: A pulse gas flow is added to the traditional fluidized bed used in Comparative Example 1. No mechanical stirring, no flow-assisting particles.

[0038] Experimental process: The difference between Comparative Example 2 and Comparative Example 1 is that, in addition to the stable fluidizing gas, the pulse device is opened, the pulse frequency is 0.05 Hz, and the pulse pressure is 0.4 MPa. At this time, the material starts to flow slowly for 180 s, and the basic fluidizing gas velocity is 0.25 m / s. At this gas velocity, the coating liquid is sprayed, the coating liquid is composed of 20 silane coupling agents (model KH560) and 20 g of anhydrous ethanol, the flow rate of the coating liquid is 2 mL / min, the flow rate of the atomizing gas is 15 L / min, and the spraying time is 20 min.

[0039] Comparative Example 3 (pulse + flow-assisting particles) Device and process: 10% by volume of spherical alumina flow-assisting particles with an average particle size of 80 μm are added to the fluidized bed with pulse gas flow used in Comparative Example 2. No mechanical stirring.

[0040] Experimental process: The difference between Comparative Example 3 and Comparative Example 2 is that spherical alumina flow-assisting particles are added to the silica material. At this time, the material starts to flow slowly for 90 s, and the basic gas velocity can be reduced to 0.22 m / s.

[0041] Comparative Example 4 (pulse + mechanical stirring) Device and process: A frame stirring paddle (100 rpm) is added to the bottom of the fluidized bed with pulse gas flow used in Comparative Example 2. No flow-assisting particles.

[0042] Experimental process: The difference between Comparative Example 4 and Comparative Example 2 is that a frame stirring paddle is added to the bottom of the fluidized bed reactor device, and the stirring paddle is set to 100 rpm. At this time, the material starts to flow slowly for 60 s, and the basic gas velocity can be reduced to 0.20 m / s.

[0043] Example 1 (pulse, stirring, and double-particle triple synergistic system) Device and process: increase the pulse airflow, mechanical stirring and flow-aiding particles in the traditional fluidized bed described in Comparative Example 1. That is, the fluidized coating device described in the present application has the functions of pulse, stirring and double particles.

[0044] Experimental process: increase the frame stirring paddle at the bottom of the fluidized bed reactor device, and set the stirring paddle speed to 100 rpm. At this time, the material starts to flow slowly for 30 s, and the basic gas speed can be reduced to 0.18 m / s.

[0045] Performance test and result The coated products were respectively subjected to the determination of coating uniformity RSD, agglomerate proportion and coating liquid utilization rate, and the test methods were as follows: Determination of coating uniformity RSD: nitrogen adsorption-desorption method (BET method) was used for determination, 8 small samples were taken from each product, and BET test was carried out on each sample. The BET specific surface area of each sample was determined. The RSD of these specific surface area values was calculated. The more uniform the coating is, the smaller the fluctuation of the specific surface area values measured by different samples.

[0046] Determination of agglomerate proportion: 100 g of the coated product was placed on a standard sieve with a pore size of 150 μm, and a sieve shaker was used for sieving for 5 minutes. The mass of the sieve upper material was accurately weighed, and the formula: agglomerate proportion (%) = (sieve upper material mass / total mass before sieving) x 100% was used for calculation. The lower the value is, the better the anti-agglomeration effect of the process is.

[0047] Determination of coating liquid utilization rate: the total mass of the carrier particles before coating m1 was accurately weighed, the total volume of the coating liquid consumed during the coating process V was recorded, and the density of the coating liquid ρ was known. After the coating was completed, all the products were collected and weighed to obtain the total mass m2. The formula: coating liquid utilization rate (%) = [(m2-m1) / (V x ρ)] x 100% was used for calculation. The higher the value is, the less the coating liquid is wasted, and the better the process economy is. The fluidization effect of the material and the test results are shown in Table 1.

[0048] Table 1: Summary of material fluidization effect and coating effect test data of comparative examples and examples

[0049] The above data show that the traditional technology cannot handle such ultra-fine viscous powder at all; single pulse has some improvement, but the fluidization starts slowly, uniformity is poor, and waste is serious; the flow aid particles significantly improve the start and microscopic mixing, and the effect is better than that of single pulse; mechanical stirring breaks the bottom agglomeration, starts faster, but the overall mixing of particles depends on airflow; the triple synergy produces a leapfrog effect: the fastest start, the most stable fluidization, the best uniformity, and the least waste. All indicators are overall and significantly better than any single or double improvement scheme. The fluidized coating device provided by the present application has pulse, stirring, and double particle triple synergy, and produces a significant synergistic gain effect in solving the problem of fluidized coating of ultra-fine powder particles.

[0050] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that: the specific embodiments of the present application can still be modified or replaced by the equivalent, without departing from the spirit and scope of the present application, any modification or equivalent replacement, which should be covered within the protection scope of the claims of the present application.

Claims

1. A fluidized bed coating device with pulse, stirring, and dual-particle triple synergy, characterized in that, include: The spray fluidized bed reactor is equipped with a heating system and a carrier gas inlet. A gas distributor is disposed in the spray fluidized bed reactor and located above the carrier gas inlet to uniformly distribute the carrier gas entering through the carrier gas inlet throughout the bed to form fluidized gas. A gas-liquid two-phase flow nozzle, located in the spray fluidized bed reactor, is connected to the gas supply unit and the coating liquid delivery tank, and is used to atomize the coating liquid into micron-sized droplets and spray them into the spray fluidized bed reactor; A mechanical shearing unit is installed at the bottom of the bed in the spray fluidized bed reactor to continuously produce local mechanical breakup of the agglomerates; A pulse air intake device, located on the spray fluidized bed reactor and connected to the air supply unit, is used to apply periodic pulse airflow to the fluidized bed to break up particle agglomeration and channeling formed during initial fluidization; The flow-aiding particles are filled in the spray fluidized bed reactor. The flow-aiding particles and the fine powder particles to be coated form a dual-particle fluidized system, which is used to prevent the fine powder from re-agglomerating through collision and friction. The particle size of the flow-aiding particles is larger than the particle size of the fine powder particles to be coated.

2. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 1, characterized in that, The spray fluidized bed reactor includes: The cylindrical reaction section, wherein the gas distributor, the mechanical shearing unit and the pulse air intake device are all located at the bottom of the cylindrical reaction section; A conical settling section is located at the bottom of the cylindrical reaction section and is connected to the cylindrical reaction section. The conical settling section expands upward in diameter, and the gas-liquid two-phase flow nozzle is located at the conical settling section.

3. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 1, characterized in that, The volume of the flow-aiding particles accounts for 5% to 20% of the total volume of the mixture of the fine powder particles to be coated and the flow-aiding particles; the particle size range of the fine powder particles to be coated is 1 to 50 μm, the particle size range of the flow-aiding particles is 50 to 150 μm, and the particle size ratio between the flow-aiding particles and the fine powder particles to be coated is 2.5 to 5:

1.

4. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 1, characterized in that, The gas supply unit also includes a carrier gas source, and a pulse gas pipeline and a fluidizing gas pipeline are connected in parallel at the outlet of the carrier gas source, wherein: The pulse air pipeline is connected to the pulse air intake device, and a buffer tank and a pulse valve are installed on the pulse air pipeline. The fluidizing gas pipeline is connected to the carrier gas inlet. A spray gas pipeline connected to a gas-liquid two-phase flow nozzle is provided on the fluidizing gas pipeline. Both the fluidizing gas pipeline and the spray gas pipeline are equipped with a mass flow meter and a control valve. A gas preheating device is also provided on the fluidizing gas pipeline located in front of the spray gas pipeline.

5. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 2, characterized in that, The ratio of the maximum diameter of the conical settling section to the diameter of the cylindrical reaction section is 1.2 to 1.5:1, and the height-to-diameter ratio of the cylindrical reaction section is 3 to 5:

1.

6. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 1, characterized in that, The gas distributor is a sintered metal plate or a perforated plate; the mechanical shearing unit is any one or a combination of a frame-type agitator, an anchor-type agitator, a paddle-type agitator, or a spiral agitator.

7. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 1, characterized in that, The flow-aiding particles are any one of alumina, silicon dioxide, and zirconium oxide; the flow-aiding particles are any one of spherical, cylindrical, cubic, and irregular shapes; the carrier gas is any one of nitrogen, argon, and helium.

8. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 1, characterized in that, An integrated material conveying system is also provided on the spray fluidized bed reactor; the material conveying system includes: a feed tank, a discharge tank, and a receiving tank, wherein: The feed tank is used to hold the fine powder particles to be coated. An observation port and a pressure detector are installed on the feed tank. A feed pipe connected to the spray fluidized bed reactor is installed at the bottom of the feed tank. The unloading tank is used to temporarily store materials. A first metal filter is installed at the top of the unloading tank. The first metal filter is connected to the exhaust gas treatment system through a first exhaust gas pipe. An unloading pipe connected to the spray fluidized bed reactor is installed on the unloading tank. A receiving pipe is installed at the bottom of the unloading pipe. The receiving tank is used to collect and store materials in batches. A detachable vibrating screen is installed on the top of the receiving tank.

9. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 2, characterized in that, A second metal filter is installed at the top of the conical settling section. The second metal filter is connected to the exhaust gas treatment system through a second exhaust pipe. Openable and closable atomizer channels are provided in the middle and bottom of the conical settling section. The coating liquid delivery pipeline passes through any one of the atomizer channels.

10. The fluidized bed coating device with pulse, stirring, and dual-particle triple synergy as described in claim 2, characterized in that, The heating system is a resistance heating furnace, which is arranged in sections surrounding the cylindrical reaction section. Each resistance heating furnace is independently controlled. Pressure detectors and temperature detectors are installed on the cylindrical reaction section.

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