Pulse combustion spray drying preparation device and method for nano-particles

Abstract

The invention relates to a pulsating combustion spray drying preparation device and method for nano-particles. The pulsating combustion spray drying preparation device comprises a feeding unit, a grading drying unit and a material collecting unit. The end of a peristaltic pump of the feeding unit is connected to a two-stage atomization assembly through a hose, the left end of the two-stage atomization assembly is connected with an air compression air pump, and the lower end of the two-stage atomization assembly is connected to the graded drying unit. When flowing out, materials in the first-stage circular pipe of the two-stage atomization assembly are impacted by high-pressure and high-speed air flow in the second-stage circular pipe to complete primary atomization, generated atomized particles are subjected to secondary atomization and drying by high-temperature and high-speed air flow in the third-stage circular pipe, and needed nano particles are prepared. The method has the advantages that uniform nano-particles can be prepared, the dried particles are prevented from being overheated, the drying temperature can be regulated and controlled, the retention rate of effective components is high, powder materials are not agglomerated, and the equipment cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of spray drying, and in particular relates to a pulsating combustion spray drying preparation device and method for nanoparticles. Background Art

[0002] Nanoparticles are widely used in the automotive, pharmaceutical and other industries due to their huge specific surface area. Due to their special properties, the production cost of nanoparticles is relatively high compared to traditional particles. Currently, the main methods for producing nanoparticles are the upward method and the downward method. The size of the nanoparticles produced by the two methods is uncontrollable, the particle size distribution is uneven, the particle stability is very poor, and it is accompanied by high production costs.

[0003] At present, the two-fluid spray technology is quite mature, using pressurized gas and liquid to mix evenly, so as to achieve the effect of gas-liquid mixed atomization. However, the atomized particles sprayed by the two-fluid nozzle are far from reaching the nanometer level, and the moisture content of the particles is relatively high, requiring further atomization and drying. At this time, a pulsating burner is connected, and the high-temperature and high-pressure impact airflow generated during pulsating combustion is used to re-atomize the atomized particles sprayed by the two-fluid nozzle to obtain nanometer-level powder particles. The moisture content of the atomized particles is greatly reduced under the mixing of the high-temperature airflow, thereby meeting the requirements for preparing nanometer powder particles.

[0004] Pulsating combustion refers to a special type of combustion between normal combustion and deflagration, in which the pressure, flow field and temperature in the combustion chamber are periodic due to the mutual coupling of the combustion process and the acoustic characteristics of the burner under certain acoustic conditions. Pulsating combustion can produce a high-temperature, high-speed, oscillating exhaust gas flow. This high-temperature and high-speed exhaust gas flow can be used for purposes such as material drying and heating, and is used to develop equipment such as pulsating combustion dryers, pulsating combustion water heaters and steam boilers. Due to the advantages of high combustion intensity and efficiency, high heat transfer efficiency, and low gas pollutant emissions, the related pulsating combustion devices have achieved certain success.

[0005] The inventors of this patent application have been engaged in the basic and applied research of pulse combustion drying for a long time, and have developed various pulse burner drying and application devices, such as multi-tube pulse combustion infrared drying device (CN110131990A), pulse combustion internal heating fluidized bed drying device (CN110131966A), etc. In view of the defects of traditional nanoparticle preparation technology, this research group combines the advantages of pulse burners that can generate high-temperature, high-speed oscillating tail gas impact flow, and cooperates with two-stage atomization components to propose a pulse combustion spray drying preparation device and method for nanoparticles. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a pulsating combustion spray drying device and method for preparing nanoparticles, which combines pulsating combustion technology with nanoparticle preparation, and solves the technical problems of uneven nanoparticles, low nanoparticle yield, high energy consumption in the preparation process, and high equipment cost in the existing nanoparticle preparation process.

[0007] The present invention solves the technical problem by the following technical solutions:

[0008] A pulsating combustion spray drying preparation device for nanoparticles, comprising a feeding unit, a graded drying unit and a material collecting unit; the feeding unit comprises a material storage tank and a peristaltic pump, the material storage tank is connected to the peristaltic pump through a hose, the end of the peristaltic pump is connected to a two-stage atomization assembly through a hose, the left end of the two-stage atomization assembly is connected to an air compression pump, and the lower end of the two-stage atomization assembly is connected to the graded drying unit;

[0009] The graded drying unit comprises a drying tower and a cyclone separator, the upper end of the drying tower is connected to a pulsating burner, and the lower end of the drying tower is connected to the cyclone separator through a drying tower connecting pipe;

[0010] The material collection unit includes a primary collector, a bag dust collector, a secondary collector and an induced draft fan. The primary collector is connected to the bottom end of the cyclone separator, the bag dust collector is connected to the top end of the cyclone separator through a cyclone separator connecting pipe, the bottom end of the bag dust collector is connected to the secondary collector, and the right end of the bag dust collector is connected to the induced draft fan.

[0011] Moreover, the two-stage atomization assembly is composed of a primary circular tube, a secondary circular tube and a tertiary circular tube; the primary circular tube is sleeved inside the secondary circular tube in a concentric circle position relationship and is connected at the middle section of the secondary circular tube; the secondary circular tube is connected to the tertiary circular tube at the end; the primary circular tube, the secondary circular tube and the tertiary circular tube are sleeved at the end in a concentric circle position relationship, the primary circular tube is in the innermost layer, the tertiary circular tube is in the outer layer, the end of the two-stage atomization assembly is placed directly above the drying tower and extends into the drying tower, the secondary circular tube and the top of the tertiary circular tube are arranged opposite to each other; the end of the peristaltic pump is connected to the top of the primary circular tube through a hose; the air compression pump is fixed to the top of the secondary circular tube through a hose using a clamp; the pulsating burner is fixed to the top of the tertiary circular tube through a clamp.

[0012] Moreover, the pulsating burner includes a combustion chamber, an air intake chamber connected to one end of the combustion chamber, a burner tail pipe connected to the other end of the combustion chamber, and a gas inlet pipe and a spark plug connected to the combustion chamber. A one-way diaphragm valve is installed at the end of the air intake chamber, and the burner tail pipe of the pulsating burner is fixed to the top of the three-stage circular tube by a clamp.

[0013] Moreover, the combustion chamber is a cylindrical 304 stainless steel cavity with a length of L1 and an outer diameter of D1, wherein L1 is 230-250 mm, D1 is 65-70 mm, and the wall thickness of the combustion chamber is 2 mm; the burner tail pipe is a cylindrical 304 stainless steel round tube with a length of L2 and an outer diameter of D2, wherein L2 is 600-650 mm, D2 is 36 mm, and the wall thickness of the burner tail pipe is 2 mm.

[0014] A method for preparing nanoparticles by pulsating combustion spray drying, using the pulsating combustion spray drying device for preparing nanoparticles, the method comprises the following steps:

[0015] 1) Feeding: Turn on the peristaltic pump and pump the liquid material in the material storage tank into the primary circular tube in the secondary atomization assembly;

[0016] 2) Primary atomization: Turn on the compressed air pump to send high-pressure and high-speed airflow into the secondary tube of the two-stage atomization assembly. When the material flows out from the end of the primary tube, it is impacted by the high-pressure and high-speed airflow in the secondary tube. When the material is ejected from the secondary tube nozzle with the high-speed airflow, primary atomization is completed, and particles close to 100nm are obtained;

[0017] 3) Burner ignition: hydrogen is introduced into the combustion chamber through the burner air inlet pipe, and air is allowed to enter the combustion chamber under the control of the diaphragm valve. The hydrogen and air entering the combustion chamber are mixed and ignited by the spark plug. The ignited mixed gas burns in the combustion chamber to generate high-temperature and high-speed airflow. The high-temperature and high-speed airflow enters the three-stage circular tube in the two-stage atomization assembly through the burner tail pipe;

[0018] 4) Secondary atomization: When the high-temperature and high-speed impact airflow entering the third-stage circular tube of the two-stage atomization component is ejected at the end, it once again impacts the primary atomized material ejected from the second-stage circular tube to complete the secondary atomization, and obtain particles less than 100nm, which are then sprayed into the drying tower for drying driven by the high-temperature airflow;

[0019] 5) Gradual drying: The nanoparticles sprayed into the drying tower continue to float and dehydrate in the drying tower driven by the high-temperature airflow. The nanoparticles that fall to the bottom of the drying tower under the action of gravity enter the cyclone separator through the pipeline driven by the induced draft fan for further drying and separation;

[0020] 6) Nanoparticle collection: The dried nanoparticle material is separated by a cyclone separator and a bag filter under the drive of an induced draft fan and is collected in a primary collector and a secondary collector.

[0021] The positive effects that the present invention can produce are:

[0022] 1. The present invention skillfully combines a pulsating burner with a secondary atomizing assembly, combines the primary atomization of liquid materials by a high-pressure, high-speed airflow generated by a high-pressure air pump and the re-atomization of the first atomized particles by a high-temperature, high-speed airflow generated by pulsating combustion, thereby achieving secondary atomization of liquid materials and preparing finer nanoparticles.

[0023] 2. The present invention makes the prepared nanoparticles more delicate and uniform by graded atomization drying of the liquid material, thus solving the problem of uneven particle fineness in the process of preparing nanoparticles by traditional technology.

[0024] 3. The present invention cleverly separates the high-temperature airflow and the material with a gas medium to avoid direct contact between the high-temperature airflow and the material pipe, thereby protecting the material from overheating and preventing the material from agglomerating, burning, and sticking to the wall due to excessive temperature near the wall.

[0025] 4. The present invention can neutralize the high-temperature gas ejected by the pulsating burner by adjusting the temperature of the air flow entering the secondary atomizing assembly through the air compression pump, thereby adjusting the drying temperature of the material, thereby making the application scope of the drying equipment larger and more extensive.

[0026] 5. The heat used in the present invention comes from pulsating combustion. Compared with the traditional superheated steam generating device, the pulsating burner device is compact, has high combustion intensity, high combustion efficiency, low pollutant emissions, simple structure, and low equipment investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention;

[0028] Figure 2 It is a structural schematic diagram of the secondary atomization assembly of the present invention;

[0029] Figure 3 It is a schematic diagram of the structure of the pulsation burner of the present invention;

[0030] Figure 4 This is an electron microscope scanning image of the particle size of cyclodextrin raw materials purchased on the market;

[0031] Figure 5 This is an electron microscope scanning diagram of the particle size of the cyclodextrin nanoparticles prepared by drying in the present invention.

[0032] Description of Reference Numerals

[0033] 1. Compressed air pump; 2. Two-stage atomization assembly; 3. Pulsating burner; 4. Material storage tank; 5. Peristaltic pump; 6. Drying tower; 7. Drying tower connecting pipe; 8. Primary collector; 9. Cyclone separator; 10. Cyclone separator connecting pipe; 11. Bag dust collector; 12. Secondary collector; 13. Draft fan. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0035] like Figure 1 As shown, a pulsating combustion spray drying preparation device for nanoparticles, the innovation of which lies in: comprising a feeding unit, an air compression pump 1, a pulsating burner 3, a two-stage atomization component 2, a graded drying unit and a material collection unit; the feeding unit comprises a material storage tank 4 and a peristaltic pump 5; the material storage tank 4 and the peristaltic pump 5 are connected by a hose with an inner diameter of 6 mm, and the hose connected to the peristaltic pump 5 is connected to the top of the primary circular pipe 2a in the two-stage atomization component 2 through a clamp; the air compression pump is fixed to the top of the secondary circular pipe 2b in the two-stage atomization component 2 through a hose with an inner diameter of 15 mm by a clamp; the burner tail pipe 3e of the pulsating burner 3 is fixed to the two-stage atomization component 2 through a clamp. The top of the tertiary circular tube 2c in the atomization component 2; the primary circular tube 2a, the secondary circular tube 2b and the tertiary circular tube 2c of the two-stage atomization component 2 are in a concentric circle structure at the end, which is placed just above the drying tower 6 and extends into the drying tower 6; the graded drying unit includes a drying tower 6 and a cyclone separator 9, and the drying tower 6 and the cyclone separator 9 are connected by pipelines; the material collecting unit includes a primary collector 8, a bag dust collector 11, a secondary collector 12 and an induced draft fan 13, and the primary collector 8 is connected to the bottom of the cyclone separator 9; the cyclone separator 9, the bag dust collector 11 and the induced draft fan 13 are connected by pipelines, and the secondary collector 12 is connected to the lower end of the bag dust collector 11.

[0036] like Figure 3 As shown, the pulsating burner 3 comprises a combustion chamber 3d, an air intake chamber 3a connected to one end of the combustion chamber 3d, a burner tail pipe 3e connected to the other end of the combustion chamber 3d, and a gas inlet pipe 3b and a spark plug 3c connected to the combustion chamber 3d, and a one-way diaphragm valve is installed at the end of the air intake chamber 3d. The combustion chamber 3d is a cylindrical 304 stainless steel cavity with a length of L1 and an outer diameter of D1, wherein L1 is 230-250 mm, D1 is 65-70 mm, and the wall thickness of the combustion chamber 3d is 2 mm; the burner tail pipe 3e is a cylindrical 304 stainless steel round pipe with a length of L2 and an outer diameter of D2, wherein L2 is 600-650 mm, D2 is 36 mm, and the wall thickness of the burner tail pipe 3e is 2 mm.

[0037] like Figure 2As shown, the two-stage atomization assembly 2 is composed of a primary circular tube 2a, a secondary circular tube 2b, and a tertiary circular tube 2c; the primary circular tube 2a is sleeved inside the secondary circular tube 2b in a concentric circle position relationship, and is connected in the middle section of the secondary circular tube 2b; the secondary circular tube 2b is connected to the tertiary circular tube 2c at the end; the primary circular tube 2a, the secondary circular tube 2b and the tertiary circular tube 2c are sleeved in a concentric circle position relationship at the end, the primary circular tube 2a is in the innermost layer, the tertiary circular tube 2c is in the outer layer, the end of the secondary atomization assembly 2 is placed directly above the drying tower 6 and extends into the drying tower 6, and the tops of the secondary circular tube 2b and the tertiary circular tube 2c are arranged oppositely. In this design, the pulsating burner is combined with the two-stage atomization assembly, and the high-pressure and high-speed airflow generated by the air compression pump is combined with the primary atomization of the liquid material and the high-temperature and high-speed airflow generated by the pulsating combustion is combined with the re-atomization of the primary atomized particles, so as to achieve the secondary atomization of the liquid material and prepare nanoparticles with smaller particle size. And through graded atomization drying, the prepared nanoparticles are made more delicate and uniform.

[0038] In this embodiment, the cold air flow flowing out of the secondary circular tube 2b in the two-stage atomization assembly is wrapped around the primary circular tube 2a to form a layer of gas medium, so that the high-temperature air flow in the tertiary circular tube 2c does not directly contact the primary circular tube 2a, effectively protecting the material from overheating and avoiding the material from clumping, burning and sticking to the wall due to excessive temperature near the wall.

[0039] In order to better adjust the temperature of the hot gas flowing out of the tertiary circular tube 2c when it contacts the primary atomized material, the cold airflow in the secondary circular tube 2b will meet the hot airflow flowing out of the tertiary circular tube 2c at the outlet position. By adjusting the temperature of the cold airflow, the effect of adjusting the temperature of the hot airflow is achieved, thereby improving the applicability of the drying equipment to materials.

[0040] A method for preparing nanoparticles by pulse combustion spray drying, the innovation of which lies in the following steps:

[0041] 1) Feeding: Turn on the peristaltic pump and pump the liquid material in the material storage tank into the first-stage circular tube in the two-stage atomization assembly;

[0042] 2) Primary atomization: Turn on the compressed air pump to send high-pressure and high-speed airflow into the secondary round tube in the two-stage atomization assembly. When the material flows out from the end of the primary round tube, it is impacted by the high-pressure and high-speed airflow in the secondary round tube. When the material is ejected from the secondary round tube nozzle with the high-speed airflow, primary atomization is completed, and particles close to 100nm are obtained;

[0043] 3) Burner ignition: hydrogen is introduced into the combustion chamber through the burner air inlet pipe, and air is allowed to enter the combustion chamber under the control of the diaphragm valve. The hydrogen and air entering the combustion chamber are mixed and ignited by the spark plug. The ignited mixed gas burns in the combustion chamber to generate high-temperature and high-speed airflow. The high-temperature and high-speed airflow enters the three-stage circular tube in the two-stage atomization assembly through the burner tail pipe;

[0044] 4) Secondary atomization: When the high-temperature and high-speed impact airflow entering the third-stage circular tube of the two-stage atomization component is ejected at the end, it once again impacts the primary atomized material ejected from the second-stage circular tube to complete the secondary atomization, and obtain particles less than 100nm, which are then sprayed into the drying tower for drying driven by the high-temperature airflow;

[0045] 5) Gradual drying: The nanoparticles sprayed into the drying tower continue to float and dehydrate in the drying tower driven by the high-temperature airflow. The nanoparticles that fall to the bottom of the drying tower under the action of gravity enter the cyclone separator through the pipeline driven by the induced draft fan for further drying and separation;

[0046] 6) Nanoparticle collection: The dried nanopowder material is separated by a cyclone separator and a bag filter under the drive of an induced draft fan and is collected in the first and second stage collectors.

[0047] The present invention uses commercially purchased cyclodextrin raw materials to dry and prepare cyclodextrin nanoparticles. The particle size of the commercially purchased cyclodextrin raw materials is shown in the electron microscope scanning diagram. Figure 4 As shown in the figure, it can be seen that the cyclodextrin particles obtained under conventional preparation conditions have the disadvantages of large particle size non-uniformity coefficient, large particle size, and non-uniform particle shape. The cyclodextrin raw material is spray-dried by the pulse combustion spray drying preparation device of the present invention, and the obtained atomized particle size electron microscope scanning diagram is as shown in Figure 5 As shown in the figure, it can be seen that the particle size distribution of the cyclodextrin particles obtained by secondary atomization is more delicate and uniform, and the particles are microspherical and have a uniform particle shape.

[0048] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A pulsating combustion spray drying device for preparing nanoparticles, characterized in that: It comprises a feeding unit, a graded drying unit and a material collecting unit; the feeding unit comprises a material storage tank (4) and a peristaltic pump (5); the material storage tank (4) and the peristaltic pump (5) are connected via a hose; the end of the peristaltic pump (5) is connected to a two-stage atomization assembly (2) via a hose; the left end of the two-stage atomization assembly (2) is connected to an air compression pump (1); the lower end of the two-stage atomization assembly (2) is connected to the graded drying unit; The graded drying unit comprises a drying tower (6) and a cyclone separator (9), the upper end of the drying tower (6) is connected to a pulsating burner (3), and the lower end of the drying tower (6) is connected to the cyclone separator (9) via a drying tower connecting pipe (7); The material collection unit comprises a primary collector (8), a bag dust collector (11), a secondary collector (12) and an induced draft fan (13); the primary collector (8) is connected to the bottom end of the cyclone separator (9); the bag dust collector (11) is connected to the top end of the cyclone separator (9) via a cyclone separator connecting pipe (10); the bottom end of the bag dust collector (11) is connected to the secondary collector (12); and the right end of the bag dust collector (11) is connected to the induced draft fan (13).

2. The pulsating combustion spray drying device for preparing nanoparticles according to claim 1, characterized in that: The two-stage atomization assembly (2) is composed of a primary circular tube (2a), a secondary circular tube (2b) and a tertiary circular tube (2c); the primary circular tube (2a) is sleeved inside the secondary circular tube (2b) in a concentric circle position relationship and is connected to the middle section of the secondary circular tube (2b); the secondary circular tube (2b) is connected to the tertiary circular tube (2c) at the end; the primary circular tube (2a) is sleeved with the secondary circular tube (2b) and the tertiary circular tube (2c) at the end in a concentric circle position relationship, the primary circular tube (2a) is in the innermost layer, and the The three-stage circular tube (2c) is in the outer layer, the end of the two-stage atomization assembly (2) is placed directly above the drying tower (6) and extends into the drying tower (6), the two-stage circular tube (2b) is arranged opposite to the top of the three-stage circular tube (2c); the end of the peristaltic pump (5) is connected to the top of the one-stage circular tube (2a) through a hose; the air compression pump (1) is fixed to the top of the two-stage circular tube (2b) through a hose by a clamp; the pulsating burner (3) is fixed to the top of the three-stage circular tube (2c) by a clamp.

3. The pulsating combustion spray drying device for preparing nanoparticles according to claim 2, characterized in that: The pulsation burner (3) comprises a combustion chamber (3d), an air intake chamber (3a) connected to one end of the combustion chamber (3d), a burner tail pipe (3e) connected to the other end of the combustion chamber (3d), and a gas inlet pipe (3b) and a spark plug (3c) connected to the combustion chamber (3d); a one-way diaphragm valve is installed at the end of the air intake chamber (3d); and the burner tail pipe (3e) of the pulsation burner (3) is fixed to the top end of the three-stage circular tube (2c) by a clamp.

4. The pulsating combustion spray drying device for preparing nanoparticles according to claim 3, characterized in that: The combustion chamber (3d) is a cylindrical 304 stainless steel cavity with a length of L1 and an outer diameter of D1, wherein L1 is 230 to 250 mm, D1 is 65 to 70 mm, and the wall thickness of the combustion chamber (3d) is 2 mm; the burner tail pipe (3e) is a cylindrical 304 stainless steel round pipe with a length of L2 and an outer diameter of D2, wherein L2 is 600 to 650 mm, D2 is 36 mm, and the wall thickness of the burner tail pipe (3e) is 2 mm.

5. A method for preparing nanoparticles by pulse combustion spray drying, characterized in that: The pulsating combustion spray drying preparation device for nanoparticles according to any one of claims 1 to 4 is used, and the steps of the method are: 1) Feeding: Turn on the peristaltic pump and pump the liquid material in the material storage tank into the primary circular tube in the secondary atomization assembly; 2) Primary atomization: Turn on the compressed air pump to send high-pressure and high-speed airflow into the secondary tube of the two-stage atomization assembly. When the material flows out from the end of the primary tube, it is impacted by the high-pressure and high-speed airflow in the secondary tube. When the material is ejected from the secondary tube nozzle with the high-speed airflow, primary atomization is completed, and particles close to 100nm are obtained; 3) Burner ignition: hydrogen is introduced into the combustion chamber through the burner air inlet pipe, and air is allowed to enter the combustion chamber under the control of the diaphragm valve. The hydrogen and air entering the combustion chamber are mixed and ignited by the spark plug. The ignited mixed gas burns in the combustion chamber to generate high-temperature and high-speed airflow. The high-temperature and high-speed airflow enters the three-stage circular tube in the two-stage atomization assembly through the burner tail pipe; 4) Secondary atomization: When the high-temperature and high-speed impact airflow entering the third-stage circular tube of the two-stage atomization component is ejected at the end, it once again impacts the primary atomized material ejected from the second-stage circular tube to complete the secondary atomization, and obtain particles less than 100nm, which are then sprayed into the drying tower for drying driven by the high-temperature airflow; 5) Gradual drying: The nanoparticles sprayed into the drying tower continue to float and dehydrate in the drying tower driven by the high-temperature airflow. The nanoparticles that fall to the bottom of the drying tower under the action of gravity enter the cyclone separator through the pipeline driven by the induced draft fan for further drying and separation; 6) Nanoparticle collection: The dried nanoparticle material is separated by a cyclone separator and a bag filter under the drive of an induced draft fan and is collected in a primary collector and a secondary collector.

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