Centrifugal spray drying device

Abstract

The utility model discloses a centrifugal spray drying device which comprises a microwave drying cavity, a gas transmission channel, a slurry transmission channel and powder separation equipment, the microwave drying cavity comprises a tower body upper part and a tower body lower part, the tower body upper part is a hollow cylinder, the tower body lower part is a circular truncated cone with a wide upper part and a narrow lower part, and a plurality of microwave generators are arranged on the side surface or the inner wall of the top of the tower body upper part; the gas transmission channel comprises an air inlet pipeline and a gas distributor, one end of the air inlet pipeline is connected with the gas distributor, and the gas distributor is arranged at the top of the side face of the microwave drying cavity; the slurry conveying channel comprises a feeding pipe and an atomizer, one end of the feeding pipe is connected with the atomizer, and the atomizer is arranged at the top of the microwave drying cavity; the powder separation equipment comprises a cyclone separator; the cyclone separator is connected with the lower part of the tower body through a pipeline A; the equipment has the advantages of high heat transfer efficiency, high drying rate, high degree of sphericity of dried powder, no hollow sphere, no annular sphere and sphere adhesion and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to a drying device, in particular to a high -speed centrifugal spray drying device. BACKGROUND

[0002] Centrifugal spray drying device is widely used in military industry, medicine, food, ceramics, building materials and chemical industry etc. field, is mainly used for preparation size between micro nanometer level's superfine powder material. The existing centrifugal spray drying equipment mainly includes the air inlet and outlet system, heating drying system, feeding system and powder separation collection system etc. composition. The centrifugal force and shearing force produced by the high -speed spinning action of the atomizer driven by the motor atomizes the slurry into small droplets, then the hot air circulation in the tower body is used to dry it quickly, and the dry powder is collected by the cyclone separator, and the powder material with the required particle size is obtained. The heating drying process has a great influence on the sphericity of the produced powder and the strength of the particles.

[0003] The existing drying mode mainly includes electric heating, gas heating and steam heating etc. mode, and these adopt external heat source to heat the mode, which not only has low drying efficiency, slow rate and can cause the sphericity and strength of the material to decrease. The reason is that the spherical liquid droplets after atomization are affected by the external heat source, and the surface will immediately shrink and solidify first, while the ball body inside is not fully dried. With the evaporation of water in the ball body, not only a large number of hollow balls or ring balls exist, but also the outer surface of the original high-temperature solidification cracks, causing the strength to decrease. The essence of this phenomenon is the difference between water evaporation and solidification shrinkage direction. SUMMARY

[0004] The utility model discloses a kind of centrifugal spray drying devices, including microwave drying cavity, gas transmission channel, slurry transmission channel, powder separation equipment.

[0005] To achieve the above object, the technical scheme adopted by the utility model is as follows:

[0006] A centrifugal spray drying device, including microwave drying cavity, gas transmission channel, slurry transmission channel, powder separation equipment.

[0007] The microwave drying cavity 5 includes tower body upper portion 5-1 and tower body lower portion 5-2, and the tower body upper portion 5-1 is a hollow cylinder, and the tower body lower portion 5-2 is a circular truncated cone with a wide upper part and a narrow lower part. A plurality of microwave generators 8 are arranged on the side or top inner wall of the tower body upper portion 5-1.

[0008] The gas transmission channel comprises an air inlet pipe 15 and a gas distributor 7, one end of the air inlet pipe 15 is connected to the gas distributor 7, and the gas distributor 7 is arranged at the top of the side of the microwave drying cavity 5;

[0009] The slurry transmission channel comprises a feed pipe 3 and an atomizer 4, one end of the feed pipe 3 is connected to the atomizer 4, and the atomizer 4 is arranged at the top of the microwave drying cavity 5;

[0010] The powder separation device comprises a cyclone separator 10, which is connected to the lower part 5-2 of the tower body through a pipe A9-1;

[0011] When the microwave generator 8 is arranged on the inner wall of the side of the upper part 5-1 of the tower body, any two microwave generators are not on the same horizontal plane and not on the same vertical plane, and the horizontal distance and the vertical distance of adjacent microwave generators are the same;

[0012] When the microwave generator 8 is arranged on the inner wall of the top of the upper part 5-1 of the tower body, the microwave generators 8 are uniformly distributed on concentric circles with the center of the top as the center.

[0013] Preferably, when the microwave generator 8 is arranged on the inner wall of the side of the upper part 5-1 of the tower body, any two microwave generators are not on the same horizontal plane and not on the same vertical plane, and the horizontal distance and the vertical distance of adjacent microwave generators are the same. The number of microwave generators 8 is preferably 6-9. The emission frequency of the microwave generator can be accurately adjusted by the controller. Preferably, the top of the upper part 5-1 of the tower body is provided with an infrared temperature measuring device to monitor the temperature change in real time. The effect is that the atomized spherical droplets will rapidly dehydrate under the action of the microwave field, and by controlling the frequency of each microwave generator, the spherical body uniformly shrinks, avoiding uneven temperature distribution or severe heating. The advantage of this kind of microwave distribution is that the heating power at different height positions and different tower walls can be adjusted. The microwave input power of the microwave generator near the top of the tower in the initial spraying stage is relatively low, about 0.8-1.0 kW, to prevent the ball from cracking and generating a larger shrinkage hole due to rapid drying. The control power of the microwave generator in the middle of the side wall is slightly higher, about 1.1-1.8 kW, to realize the secondary rapid dehydration of the ball and ensure that the ball will not produce excessive adhesion during falling. The input power of the lowest microwave generator is the highest, about 1.9-2.4 kW, so that the water generated in the microwave drying cavity can be rapidly evaporated and discharged from the air outlet at the lower part of the tower body, avoiding the cracking caused by the secondary moisture absorption of the dried ball. By setting the action frequency and time of each microwave generator, the water in the microwave drying cavity is uniformly and rapidly dried, avoiding the problems of partial adhesion and decrease of sphericity of the material during the falling process, but also appropriately increasing the height of the tower and the investment of the equipment.

[0014] Preferably, the microwave generator 8 is arranged on the top of the tower body upper part 5-1, and is uniformly distributed on concentric circles with the center of the top as the center. The number of concentric circles can be 2-4, and the number of microwave generators 8 on each concentric circle can be 2-4. The emission frequency of the microwave generator can be accurately adjusted by the controller, and an infrared temperature measuring device is arranged on the side of the tower body upper part 5-1 to monitor the temperature change in real time. The effect produced is that the atomized spherical droplets will rapidly dehydrate under the action of the microwave field, and by controlling the frequency of each microwave generator, the spherical body is uniformly shrunk, avoiding uneven temperature distribution or severe heating. The advantage of this kind of microwave distributor is that by adjusting the power of the microwave generator at different positions, different sizes of spherical materials can be quickly dried in the same plane, and the adhesion of large and small balls can be avoided. Generally, the power of the microwave generator controlled to the position close to the center of the top is in the range of 800W-1000W, and the power of the microwave generator controlled to the position far from the center of the top is in the range of 1.2 kW-1.6 kW, and all the microwave generators are controlled to start heating at the same time, so that the inner small balls and the outer large balls can be quickly dried in the same falling plane, avoiding the adhesion of large and small balls. Due to the rapid drying of the outer large balls, part of the sphericity may decrease, but due to the rapid drying rate of this method, the equipment height of the microwave drying cavity can be reduced while meeting the water evaporation amount, and the production operation is more convenient and the equipment investment is reduced.

[0015] Preferably, the gas transmission channel is also provided with a blower 13 and a heater 14, and the heater 14 is arranged on the air inlet pipeline 15, and the blower 13 is connected with the other end of the air inlet pipeline 15. The air passes through the blower, the heater, the air inlet pipeline and the gas distributor in sequence to reach the inside of the microwave drying cavity, and then passes through the cyclone separator and the bag-type dust collector in sequence at the lower part of the microwave drying cavity, and is exhausted under the action of the induced draft fan.

[0016] Preferably, the slurry transmission channel is also provided with a stirred tank 1 and a feed pump 2, and the feed pump 2 is arranged on the feed pipeline 3, and the stirred tank 1 is connected with the other end of the feed pipeline 3. The liquid slurry in the stirred tank is directly sprayed into the inside of the microwave drying cavity from the top through the feed pump, the feed pipeline and the atomizer.

[0017] Preferably, the powder separation further comprises a bag-type dust collector 11 connected with the cyclone separator 10 through the pipeline B9-2. Preferably, the outlet of the bag-type dust collector 11 is connected with the induced draft fan 11. The powder separation device mainly separates the dried powder according to the required particle size, and recovers the generated superfine powder to avoid air pollution.

[0018] Preferably, the microwave drying cavity 5, cyclone 10, the bottom of cloth bag dust collector 11 is provided with collection tank A 16-1, collection tank B 16-2, collection tank C 16-3 respectively.

[0019] Preferably, the gas distributor is a nozzle structure, and the outlet has a conical distributor.

[0020] Preferably, the atomizer is a circular ring with a certain thickness, and the circular ring is provided with circular holes at equal intervals.

[0021] The outer wall and the inner wall of the microwave drying cavity are embedded with a silicon nitride coating 6 as a wave-absorbing material / heat preservation device.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] 1. The present application solves the problems of low drying efficiency and uneven temperature distribution. The present application uses microwave heating method and combines power regulation of microwave generators at different positions to avoid different sample shrinkage rates caused by uneven temperature field distribution, greatly improving the uniformity and drying efficiency of the sample.

[0024] 2. The present application solves the problems of low sphericity and poor strength of the obtained product. The present application uses the microwave heating characteristics to avoid the problem that water evaporation and solidification directions are opposite caused by heat conduction, and at the same time, the drying process from inside to outside makes the microsphere sample have higher sphericity, and avoids the generation of hollow spheres to improve the strength of the microspheres.

[0025] 3. The present application solves the problem of adhesion caused by different drying rates of large and small balls caused by centrifugal spray. The present application uses the design of top microwave heating to avoid the adhesion caused by the fact that large balls dry slower than small balls during the material descending process, and through optimization of the acting power and time of the inner and outer ring microwave generators, the present application obtains non-adhesion and high-sphericity microsphere powder. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a structure diagram of the centrifugal spray drying device of the present application;

[0027] Figure 2 It is a position distribution diagram of the microwave generator arranged on the inner wall of the side surface of the upper part 5-1 of the tower body at a certain angle;

[0028] Figure 3 It is a position distribution diagram of the microwave generator arranged on the inner wall of the top of the upper part 5-1 of the tower body.

[0029] Figure 4 The vertical microwave generator position distribution diagram on the side inner wall of the upper part 5-1 of the tower body of the comparative example 1 is shown in the figure;

[0030] In the figure, 1 is a stirred tank, 2 is a feeding pump, 3 is a feeding pipeline, 4 is an atomizer, 5 is a microwave drying cavity, 5-1, 6 is a silicon nitride coating, 7 is a gas distributor, 8 is a microwave generator, 9-1 is a pipeline A, 9-2 is a pipeline B, 9-3 is a pipeline C, 10 is a cyclone separator, 11 is a bag-type dust collector, 12 is an induced draft fan, 13 is a supply fan, 14 is a heater, 15 is an air inlet pipeline, 16-1 is a collection tank A, 16-2 is a collection tank B, 16-3 is a collection tank C;

[0031] Figure 5 The SEM diagrams of the samples after spraying of the example 1, 2 and the comparative example 1 are shown in the figure (a is the example 1, b is the example 2, and c is the comparative example 1). DETAILED DESCRIPTION

[0032] The embodiments of the utility model are explained in detail below with reference to the drawings.

[0033] The liquid slurry in the embodiments is an inorganic salt suspension liquid containing molecular sieves.

[0034] The sample morphology observation is carried out by using a JSM-IT200 model electron microscope of Japan, and the sample needs to be reduced before testing, and then vacuum testing is carried out.

[0035] Example 1

[0036] As shown in the figures, Figure 1 and Figure 2 The centrifugal spray drying device includes a microwave drying cavity, a gas transmission channel, a slurry transmission channel and a powder separation device.

[0037] The microwave drying cavity 5 includes a tower body upper part 5-1 and a tower body lower part 5-2, the tower body upper part 5-1 is a hollow cylinder, the tower body lower part 5-2 is a circular truncated cone with a wide upper part and a narrow lower part, six microwave generators (8-1, 8-2, 8-3, 8-4, 8-5, 8-6) are arranged on the side inner wall of the tower body upper part 5-1, any two microwave generators are not on the same horizontal plane or the same vertical plane, and the horizontal distance and the vertical distance of adjacent microwave generators are the same (the specific arrangement mode is as follows); an infrared temperature measuring device is arranged on the top of the tower body upper part 5-1, and the bottom of the microwave drying cavity 5 is respectively provided with a collection tank A 16-1;

[0038] The gas transmission channel includes a supply fan 13, a heater 14, an air inlet pipeline 15 and a gas distributor 7, one end of the air inlet pipeline 15 is connected with the gas distributor 7, the other end is connected with the supply fan 13, the heater is arranged on the air inlet pipeline 15, and the gas generator 7 is arranged at the top of the side of the microwave drying cavity.

[0039] The slurry conveying channel comprises a stirred tank 1, a feed pump 2, a feed pipe 3, an atomizer 4, one end of the feed pipe 3 is connected to the atomizer 4, the other end is connected to the stirred tank 1, the feed pump 2 is arranged on the feed pipe 3, and the atomizer 4 is arranged at the top of the microwave drying cavity 5;

[0040] The powder separation device comprises a cyclone separator 10 and a bag-type dust collector 11, the cyclone separator 10 is connected to the lower part 5-2 of the tower body through a pipeline A9-1, the bag-type dust collector 11 is connected to the cyclone separator 10 through a pipeline B9-2, and the outlet of the bag-type dust collector 11 is connected to an induced draft fan 11; the bottom parts of the cyclone separator 10 and the bag-type dust collector 11 are respectively provided with a collection tank B16-2 and a collection tank C16-3.

[0041] The microwave generator is specifically arranged as follows: a circular hole is opened on the side of a vertical position at a distance of about 0.2 m from the top of the tower, a first generator is fixed, and there is a microwave generator every 0.2 m or so in the vertical direction. At the same time, in order to ensure that the powders at different positions are uniformly heated, the straight-line distance between the centers of two adjacent microwave generators in the overhead structure is about 0.7 m or so, so as to ensure that the powder samples at different angles can be uniformly dried.

[0042] The working process is as follows:

[0043] Firstly, the liquid slurry enters the feed pipe 3 through the feed pump 2, and then is discharged at the outlet of the atomizer 4. The atomizer is a high-speed rotor with a circular hole, so that the slurry entering the atomizer can be sheared into small droplets under the action of centrifugal force. Subsequently, the circulating air system starts to work under the action of the air supply fan 13 and the induced draft fan 12, compressed air is transported to the gas distributor 7 in the air inlet pipe 15, the gas distributor is an equipment with a small conical hole, which can play a role in secondary pressurization of compressed air, so that the compressed air can have a better dispersion effect on the small droplets, avoiding the agglomeration and adhesion of the droplets in the hot air drying process. Then the microwave generator 8 arranged on the side inner wall of the upper part 5-1 of the tower body starts to dry the atomized small droplets, and the power of the six microwave generators arranged from the top to the bottom controls the drying rate of the small droplets, avoiding the cracking of the spheres caused by too fast drying. At the same time, in order to avoid the harm of microwave transmission to human health, the inner wall and the outer wall of the tower body are embedded with silicon nitride ceramic lining 6 as wave-absorbing material. After the sample is dried, the powder sample is brought into the cyclone separator 10 under the action of the induced draft fan 12, and the particles with appropriate size are obtained after cyclone separation, and then the ultrafine powder is sucked into the bag-type dust collector 11 for recycling, and the sample particles can be obtained by taking down the bottom recovery tanks A, B and C. Finally, the gas is exhausted under the action of the induced draft fan.

[0044] The controller is opened, the power of the microwave generator is controlled from low to high from top to bottom, the power of the 6 microwave generators is 900W, 1100W, 1300W, 1800W, 2000W and 2300W respectively, the rotating frequency is set to 230Hz, the air inlet temperature is 220 DEG C, the air outlet temperature is 130 DEG C, the material can be fed when the infrared display temperature is stable, the prepared inorganic slurry is fed under the action of the feeding pump, and the feeding rate is kept at 30mL / min -1 The microwave generator and the motor are turned off after spraying, and the particle powder is collected in the collecting pipe B at the bottom of the cyclone separator for morphology determination.

[0045] From Figure 5 (a), it can be found that the sphericity of the microsphere powder is improved, and the broken ball rate is obviously reduced, which shows that the change of the heating mode effectively improves the drying efficiency and improves the sphericity and strength of the ball.

[0046] Example 2

[0047] As shown in Figure 3 , the microwave generators 8 are uniformly arranged on the inner wall of the top of the upper part 5-1 of the tower body, the number of concentric circles is 3, the distances of the 3 concentric circles from the center are 0.5m, 1.0m and 1.4m respectively, 3 microwave generators are arranged on each concentric circle, the powers of the 3 microwave generators on each concentric circle are the same, and from inside to outside, the powers of the microwave generators on the 3 concentric circles are 800W, 1200W and 1500W respectively. The remaining operations are the same as those in example 1.

[0048] From Figure 5 (b), it can be found that the sphericity of the microsphere powder is improved, and the adhesion phenomenon is obviously reduced, which shows that the change of the heating mode effectively improves the drying efficiency and improves the drying rate of the large ball.

[0049] Comparative Example 1

[0050] As shown in Figure 4 , the microwave generators are arranged on the same vertical line of the inner wall of the side of the upper part 5-1 of the tower body, and the remaining operations are the same as those in example 1.

[0051] From Figure 5 (c), it can be found that the sphericity of the microsphere powder is low, and there are obvious adhesion balls. It shows that the drying efficiency is effectively improved by changing the distribution position of the microwave generator, and the sphericity of the ball is improved.

[0052] The above only describes the preferred embodiments of the utility model, and does not limit the utility model, and any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A centrifugal spray drying device, comprising a microwave drying cavity, a gas transmission channel, a slurry transmission channel, and a powder separation device. The microwave drying cavity (5) comprises a tower upper part (5-1) and a tower lower part (5-2), the tower upper part (5-1) is a hollow cylinder, and the tower lower part (5-2) is a circular truncated cone with a wide upper part and a narrow lower part; a plurality of microwave generators (8) are arranged on the side or top inner wall of the tower upper part (5-1). The gas transmission channel comprises an air inlet pipe (15) and a gas distributor (7), one end of the air inlet pipe (15) is connected to the gas distributor (7), and the gas distributor (7) is arranged at the top of the side of the microwave drying cavity (5). The slurry transmission channel comprises a feeding pipe (3) and an atomizer (4), one end of the feeding pipe (3) is connected to the atomizer (4), and the atomizer (4) is arranged at the top of the microwave drying cavity (5). The powder separation device comprises a cyclone separator (10), and the cyclone separator (10) is connected to the tower lower part (5-2) through a pipe A (9-1). When the microwave generators (8) are arranged on the side inner wall of the tower upper part (5-1), any two microwave generators are not on the same horizontal plane or the same vertical plane, and the horizontal distance and the vertical distance of adjacent microwave generators are the same. When the microwave generators (8) are arranged on the top inner wall of the tower upper part (5-1), the microwave generators (8) are uniformly distributed on concentric circles with the center of the top as the center.

2. The centrifugal spray drying apparatus of claim 1, wherein, The side inner wall of the tower upper part (5-1) is provided with microwave generators (8), and the top of the tower upper part (5-1) is provided with an infrared temperature measuring device.

3. The centrifugal spray drying apparatus of claim 1, wherein, The number of concentric circles is 2-4, and the number of microwave generators on each concentric circle is 2-4.

4. The centrifugal spray drying apparatus of claim 3, wherein, The side of the tower upper part (5-1) is provided with an infrared temperature measuring device.

5. The centrifugal spray drying apparatus of claim 1, wherein, The gas transmission channel is further provided with a blower (13) and a heater (14), the heater is arranged on the air inlet pipe (15), and the blower (13) is connected to the other end of the air inlet pipe (15).

6. The centrifugal spray drying apparatus of claim 1, wherein, The slurry transmission channel is further provided with a stirring kettle (1) and a feeding pump (2), the feeding pump (2) is arranged on the feeding pipe (3), and the stirring kettle is connected to the other end of the feeding pipe (3).

7. The centrifugal spray drying apparatus of claim 1, wherein, The powder separation device further comprises a bag-type dust collector (11), and the bag-type dust collector (11) is connected to the cyclone separator (10) through a pipe B (9-2).

8. The centrifugal spray drying apparatus of claim 1, wherein, The bottoms of the microwave drying cavity (5), the cyclone separator (10), and the bag-type dust collector (11) are respectively provided with a collection tank A (16-1), a collection tank B (16-2), and a collection tank C (16-3).

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