A multi-element hot air spray dryer and drying method

Abstract

The present application relates to the field of spray drying technology, and discloses a multi-element hot air spray dryer and a drying method, wherein a multi-element hot air spray dryer comprises a drying tank, a drying chamber is provided in the drying tank, an outer channel for introducing a low-flow rate and sub-high-temperature airflow into the drying chamber is provided on the drying tank, an inner channel for introducing a high-flow rate and high-temperature airflow into the drying chamber is provided in the outer channel, and an atomizing device is installed in the drying chamber at a position corresponding to the inner channel. The present application has the effect of high drying efficiency and preventing materials from adhering to the inner wall.

Description

Technical Field

[0001] The present application relates to the field of spray drying technology, and in particular to a multi-element hot air spray dryer and a drying method. Background Art

[0002] A spray dryer is a device that can simultaneously complete drying and granulation processes. It is mostly used to make dry fuel, soap powder, inorganic salts, etc.

[0003] The common spray dryer structure at present includes a fuselage, a drying chamber is opened in the fuselage, a spray device is installed on the top of the drying chamber, and a hot air channel for introducing high-temperature airflow is arranged on the surrounding side of the spray device at the top of the drying chamber. When in use, the material solution is first heated, and then atomized and sprayed into the drying chamber through the spray device. At the same time, the hot air channel inputs hot air into the drying chamber. In the process of the hot air carrying the atomized material downward, the moisture is removed to complete the drying and granulation of the material.

[0004] In the above-mentioned related technologies, the temperature of the inner wall of the drying chamber is lower than that of the atomized material. During the falling process of the atomized material, it is easy to contact with the inner wall of the drying chamber. The moisture in the material particles at the top is not completely evaporated, and the material is easy to adhere to the inner wall of the drying chamber. Summary of the invention

[0005] In order to prevent the dry material from adhering to the inner wall, the present application provides a multi-element hot air spray dryer and a drying method.

[0006] The present application provides a multi-element hot air spray dryer adopts the following technical solution:

[0007] A multi-element hot air spray dryer comprises a drying tank, a drying chamber is provided in the drying tank, an outer channel for introducing a low-flow rate and sub-high-temperature airflow into the drying chamber is provided on the drying tank, an inner channel for introducing a high-flow rate and high-temperature airflow into the drying chamber is provided in the outer channel, and an atomizing device is installed in the drying chamber at a position corresponding to the inner channel.

[0008] By adopting the above technical solution, when in use, the atomizing device sprays the material into the high-velocity and high-temperature airflow supplied from the inner channel, the material absorbs heat, and the moisture on the outer surface of the particles is rapidly vaporized to the expected moisture content. At the same time, the volume expands, and the particles diffuse into the low-velocity and sub-high-temperature airflow supplied from the outer channel for further drying. In the present application, an outer channel is set up, and a low-velocity and sub-high-temperature airflow is supplied into the drying tank to form an air curtain for suppressing the circumferential scattering of undried materials, accelerate the falling speed of edge materials, and reduce the diffusion radius of the material drying process, thereby greatly reducing the probability of the material contacting the inner wall before drying, and achieving the effect of preventing the material from adhering to the inner wall.

[0009] Preferably, a rectifying plate for rectifying the airflow into parallel airflow is provided in one end of the outer channel and the inner channel close to the drying tank.

[0010] By adopting the above technical solution, the mutual interference between the high-speed and high-temperature airflow and the low-speed and second-high-temperature airflow is reduced.

[0011] Preferably, a partition is provided in the drying chamber on one side of the atomization device, an upper discharge channel for discharging materials is formed between the partition and the inner wall of the drying chamber, and a cyclone separation device connected to the upper discharge channel is provided on the side wall of the drying tank.

[0012] By adopting the above technical solution, the particles suspended in the drying chamber are discharged in sequence through the upper discharge channel and the cyclone separation device.

[0013] Preferably, an isolation plate is installed in the upper discharge channel, and a lower discharge channel is formed between the isolation plate and the inner wall of the drying chamber, the inlet height of the lower discharge channel is lower than the inlet height of the upper discharge channel, and the cyclone separation device is connected to the lower discharge channel; a porous plate is provided at the bottom of the drying tank, and a dehumidification warm air channel is provided below the porous plate.

[0014] By adopting the above technical solution, the particles falling on the bottom of the drying chamber have high humidity and large volume. The dehumidification warm air channel blows up the particles through the porous plate and performs secondary drying on the particles to ensure the drying effect of the particles.

[0015] Preferably, the height of one side of the porous plate close to the inlet of the lower discharge channel is lower than that of the other side.

[0016] By adopting the above technical solution, the particles are guided toward the entrance of the downward discharge channel by utilizing their own weight.

[0017] Preferably, a dehumidification cold air channel is provided below the porous plate corresponding to the inlet of the lower discharge channel.

[0018] By adopting the above technical solution, when the particles enter the lower discharge channel, the dehumidified cold air flow is used to cool the particles to prevent the particles from adhering to the inner wall of the cyclone separation equipment. In addition, the dehumidified cold air channel is arranged toward the entrance of the lower discharge channel, and the dehumidified cold air flow enters the cyclone separation equipment through the lower discharge channel, thereby playing a role in cooling the cyclone separation equipment.

[0019] Preferably, the cyclone separation equipment includes a secondary cyclone separator and a primary cyclone separator connected to an upper interface of the secondary cyclone separator, the feed port of the primary cyclone separator is connected to the upper discharge channel, and the secondary cyclone separator is connected to the lower discharge channel.

[0020] By adopting the above technical solution, since the temperature of the particles suspended in the drying chamber is relatively high, in order to prevent the particles from sticking to the wall due to high temperature, the suspended particles are initially cooled down in the first-stage cyclone separator and then further cooled down sufficiently in the second-stage cyclone separator, thereby preventing the particles from sticking to the wall.

[0021] Preferably, a first spray head is installed on the top of the drying chamber, a second spray head is installed in the upper discharge channel, and a third spray head is installed in the lower discharge channel.

[0022] By adopting the above technical solution, the drying tank is fully cleaned.

[0023] The present application provides a multi-element hot air spray drying method using the following technical solution:

[0024] A multi-element hot air spray drying method comprises the following steps:

[0025] S1, forming internal parallel airflow in a dry working environment;

[0026] S2, multiple annular parallel airflows are arranged outside the inner parallel airflow, the airflow directions of the multiple annular parallel airflows are parallel to the inner parallel airflow, the temperature of the inner parallel airflow is higher than that of the annular parallel airflow, the temperature of the multiple annular parallel airflows gradually increases from the outside to the inside, the flow velocity of the inner parallel airflow is higher than that of the annular parallel airflow, and the flow velocity of the multiple annular parallel airflows gradually increases from the outside to the inside;

[0027] S3, spray the material by pressure atomization in the inner parallel airflow.

[0028] By adopting the above technical solution, an annular parallel airflow is added to form an air curtain for suppressing the circumferential dispersion of undried materials, reducing the diffusion radius of the material drying process, thereby greatly reducing the probability of the material contacting the inner wall before drying, and achieving the effect of preventing the material from adhering to the inner wall. In addition, the annular parallel airflow also provides a cooling and drying environment for the particles, fully ensuring that the inside of the particles is fully dried, thereby improving the quality of drying and granulation.

[0029] In summary, the present application includes at least one of the following beneficial technical effects:

[0030] To prevent undried materials from adhering to the inner wall, an external channel is set up to supply low-velocity and sub-high-temperature airflow, and an air curtain is formed around the high-velocity and high-temperature airflow to suppress the circumferential dispersion of undried materials, thereby reducing the diffusion radius of the material drying process, thereby greatly reducing the probability of the material contacting the inner wall before it is dried, and achieving the effect of preventing the material from adhering to the inner wall;

[0031] Reduce the volume of the drying chamber. The atomized material particles are distributed in the drying chamber in a normal distribution. This application reduces the diffusion radius of the material drying process by setting an external channel, and reduces the volume of the drying chamber to less than one-fifth of the volume of the traditional drying chamber;

[0032] The drying granulation efficiency is greatly improved. The drying method applied for is two steps. In the first step, the atomized particles are subjected to high temperature treatment in the inner channel, and the moisture on the surface of the particles is quickly gasified. In the second step, under the action of gas expansion, the particles are transferred to the outer channel, and the water vapor in the particles is completely discharged by the secondary high temperature treatment, which is fully dried and has a higher drying granulation efficiency.

[0033] The granules after drying and granulation have high quality. In this application, the outer surface of the granules is first dried to the expected moisture content in an instant. At this time, the outer surface of the granules is still soft. Then, a secondary high temperature treatment is performed to further dry the moisture inside the granules. The moisture inside the granules vaporizes, expands, breaks, and is discharged. The lines formed on the outer surface of the granules can be automatically restored, thereby ensuring that the surface of the granules after granulation is round. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a multi-element hot air spray dryer according to an embodiment of the present application.

[0035] Explanation of the reference numerals: 1. Drying tank; 2. Drying chamber; 3. External channel; 4. Internal channel; 5. Atomizing device; 6. Rectifier plate; 7. Partition plate; 8. Upper discharge channel; 9. Isolation plate; 10. Lower discharge channel; 11. Perforated plate; 12. Dehumidification warm air channel; 13. Dehumidification cold air channel; 14. Secondary cyclone separator; 15. Primary cyclone separator; 16. First spray head; 17. Second spray head; 18. Third spray head. DETAILED DESCRIPTION

[0036] The following is combined with Figure 1 This application is described in further detail.

[0037] The embodiments of the present application disclose a multi-element hot air spray dryer and a drying method.

[0038] Reference Figure 1A multi-element hot air spray dryer comprises a drying tank 1, the cross section of the drying tank 1 is rectangular or circular, a drying chamber 2 is provided in the drying tank 1, an outer channel 3 for introducing a low-flow rate and sub-high-temperature airflow into the drying chamber 2 is installed on the top of the drying tank 1, the airflow temperature introduced by the outer channel 3 is 70°C-100°C, an inner channel 4 for introducing a high-flow rate and high-temperature airflow into the drying chamber 2 is arranged in the outer channel 3, the airflow temperature introduced by the inner channel 4 is 200°C-345°C, the outer channel 3 and the inner channel 4 are cylindrical channels, and the outer channel 3 and the inner channel 4 are concentrically arranged, an atomizing device 5 is installed in the drying chamber 2 at a position corresponding to the inner channel 4, the atomizing device 5 is arranged at the center of the inner channel 4, the spray direction of the atomizing device 5 is arranged downward, and the atomizing device 5 adopts a pressure atomizing nozzle.

[0039] When in use, the atomizing device 5 sprays the liquid raw material into the drying chamber 2. The atomized raw material first contacts with the high-speed and high-temperature airflow, and the moisture evaporates instantly from the surface of the particles. The outer surface of the particles is instantly dried to the expected moisture content. As the moisture changes from liquid to gas, the volume of the atomized raw material expands rapidly and diffuses into the low-speed and sub-high-temperature airflow. By lowering the airflow temperature, the surface of the particles is prevented from coking or forming a dry film. Coking will damage the quality of the material, and if a dry film is formed, it will hinder the discharge of moisture inside the particles. After sufficient drying, the water vapor bubbles inside the particles burst, and the internal moisture can diffuse out, destroying the drying process. The film is wrinkled, cracked or multi-layered under the outer surface of the particles, which reduces the quality of the particles; in the low-speed and high-temperature airflow, the water vapor bubbles inside the particles burst and the internal moisture is discharged. Since the outer surface of the particles is at the expected moisture content, the surface of the particles is relatively soft, and the ruptured water vapor bubbles can be reclosed, thereby ensuring the quality of particle drying; since the low-speed and high-temperature airflow is arranged around the high-speed and high-temperature airflow, under the action of pressure, the particles move toward the high-speed and high-temperature airflow during the falling process, which increases the initial drying speed while allowing the particles to stay in the high-speed and high-temperature airflow, thereby preventing undried objects from adhering to the inner wall.

[0040] Reference Figure 1 A rectifying plate 6 for rectifying the airflow into parallel airflow is provided in the outer channel 3 and the inner channel 4 at one end close to the drying tank 1. In this embodiment, the rectifying plate 6 adopts a honeycomb module made of a porous disc and a thin plate to guide the airflow to flow vertically downward to reduce the mutual interference between the high-speed and high-temperature airflow and the low-speed and low-temperature airflow, so as to form an air curtain and prevent the undried matter from adhering to the inner wall.

[0041] A partition 7 is provided on one side of the atomizing device 5 in the drying chamber 2, and an upper discharge channel 8 for discharging is formed between the partition 7 and the inner wall of the drying chamber 2. A cyclone separation device connected to the upper discharge channel 8 is provided on the side wall of the drying tank 1. The cyclone separation device is a two-stage cyclone separator, which includes a primary cyclone separator 15 and a secondary cyclone separator 14. The primary cyclone separator 15 is connected to the upper interface of the secondary cyclone separator 14, and the feed port of the primary cyclone separator 15 is connected to the upper discharge channel 8. The particles suspended in the drying chamber 2 have low water content and light weight. They enter the primary cyclone separator 15 through the upper discharge channel 8 with a higher opening to complete solid-gas separation, and then fall into the secondary cyclone separator 14, and are discharged after separation once more. Because the temperature of the particles suspended in the drying chamber 2 is relatively high, in order to avoid the particles from sticking to the wall due to high temperature, the suspended particles are initially cooled down through the primary cyclone separator 15, and then further cooled down in the secondary cyclone separator 14 to avoid the particles from sticking to the wall.

[0042] Reference Figure 1 An isolation plate 9 is installed in the upper discharge channel 8, and a lower discharge channel 10 is formed between the isolation plate 9 and the inner wall of the drying chamber 2. The entrance height of the lower discharge channel 10 is lower than the entrance height of the upper discharge channel 8. The feed port of the secondary cyclone separator 14 is connected with the lower discharge channel 10. A porous plate 11 is provided at the bottom of the drying tank 1. The height of one side of the porous plate 11 close to the entrance of the lower discharge channel 10 is lower than the other side. The particles at the bottom are guided to approach the lower discharge channel 10 by gravity. A dehumidified warm air channel 12 is provided at the lower part of the guide plate corresponding to the atomizing device 5. When in use, a dehumidified warm air flow is introduced into the dehumidified warm air channel 12. The particles at the bottom of the drying chamber 2 have a high water content and a heavy mass. The dehumidified warm air flow blows the particles up and down while floating toward the lower discharge channel 10, and enters the secondary cyclone separator 14 from the lower discharge channel 10 to complete the separation of the particles.

[0043] The temperature of the particles entering the secondary cyclone separator 14 from the lower discharge channel 10 is high. In order to avoid sticking to the wall, a dehumidified cold air channel 13 is provided at the bottom of the guide plate corresponding to the entrance of the lower discharge channel 10. When the particles enter the lower discharge channel 10, the dehumidified cold air flow is used to cool the particles. In addition, the dehumidified cold air channel 13 is arranged toward the entrance of the lower discharge channel 10, and the dehumidified cold air flow enters the secondary cyclone separator 14 and the primary cyclone separator 15 through the lower discharge channel 10, thereby playing a role in cooling the cyclone separation equipment.

[0044] A first spray head 16 is installed on the top of the drying chamber 2, a second spray head 17 is installed in the upper discharge channel 8, and a third spray head 18 is installed in the lower discharge channel 10, which are used to clean different positions in the drying tank 1 to avoid cleaning dead corners.

[0045] In summary, the multi-element hot air spray dryer disclosed in this application has at least the following advantages:

[0046] First, prevent undried materials from adhering to the inner wall; by setting up the outer channel 3, a low-flow rate and sub-high-temperature airflow is supplied, and an air curtain is formed around the high-flow rate and high-temperature airflow to suppress the circumferential dispersion of undried materials, thereby reducing the diffusion radius of the material drying process, thereby greatly reducing the probability of the material contacting the inner wall before drying, and achieving the effect of preventing the material from adhering to the inner wall.

[0047] Second, the volume of the drying chamber is reduced; the atomized material particles are distributed in the drying chamber in a normally distributed manner. In order to prevent the atomized material from contacting the inner wall of the drying chamber before it is dried, the radius of the drying chamber is usually increased in the traditional dryer. However, the present application reduces the diffusion radius of the material drying process by setting an external channel 3, thereby reducing the volume of the drying chamber to less than one fifth of the volume of the traditional drying chamber.

[0048] Third, the drying and granulation efficiency is greatly improved; the traditional drying device only uses one pipeline to introduce hot air flow into the drying chamber, and the temperature in the drying chamber is stable. For example, the temperature in the drying chamber is 70°C-150°C. The particles need a long time to be completely dried, and the drying efficiency is very low. The drying method applied for is two-step. In the first step, the atomized particles are subjected to high temperature treatment in the inner channel 4, and the moisture on the surface of the particles is quickly vaporized. In the second step, under the action of gas expansion, the atomized particles are transferred to the outer channel 3, and the water vapor in the particles is completely discharged by the secondary high temperature treatment, which is fully dried and has a higher drying and granulation efficiency.

[0049] Fourthly, the product quality of the dried granulated product is high. In the traditional method, in order to improve the drying efficiency, the drying temperature is forcibly increased. For example, the drying chamber temperature is 150°C-450°C. At this time, the temperature is too high. For sugars or powders with high low-melting-point fat content, the surface of the particles is prone to coking or hardening, affecting the product quality. The present application adopts a step-by-step drying method. In the first step, the outer surface of the particles is instantly dried to the expected moisture content. At this time, the outer surface of the particles is still soft. In the second step, a secondary high-temperature treatment is performed to further dry the moisture inside the particles. The moisture inside the particles vaporizes, expands, breaks, and is discharged. The lines formed on the outer surface of the particles can be automatically restored, thereby ensuring that the surface of the particles after granulation is round.

[0050] Fifth, the drying degree is high, and a dehumidification warm air channel 12 is arranged at the bottom of the drying chamber to perform secondary drying on the particles.

[0051] Sixth, hot particles are prevented from adhering to the cyclone separation device; a dehumidification cold air channel 13 is provided at the entrance of the lower discharge channel 10 corresponding to the lower portion of the guide plate to cool the particles with high humidity before they enter the cyclone separation device, thereby effectively preventing hot particles from adhering to the cyclone separation device.

[0052] A multi-element hot air spray drying method comprises the following steps:

[0053] S1, forming an inner parallel airflow in the dry working environment, the direction of the inner parallel airflow is from top to bottom, and the cross section of the inner parallel airflow is circular;

[0054] S2, one or more annular parallel airflows are arranged outside the inner parallel airflow, the annular parallel airflow adopts a circular annular parallel airflow, the inner parallel airflow is arranged coaxially with the annular parallel airflow, the multiple annular parallel airflows and the inner parallel airflow have the same airflow direction, the temperature of the inner parallel airflow is higher than that of the annular parallel airflow, the temperature of the multiple annular parallel airflows gradually increases from the outside to the inside, the flow rate of the inner parallel airflow is higher than that of the annular parallel airflow, and the flow rate of the multiple annular parallel airflows gradually increases from the outside to the inside. In this embodiment, taking the setting of one annular parallel airflow as an example, the temperature of the inner parallel airflow is 200°C-345°C, and the temperature of the outer annular parallel airflow is 70°C-100°C;

[0055] S3, spray the material by pressure atomization in the inner parallel airflow.

[0056] The implementation principle of a multi-element hot air spray dryer in the embodiment of the present application is as follows: after the atomized material is sprayed into the inner parallel airflow, since the temperature of the inner parallel airflow is much higher than the boiling temperature of water, the material quickly absorbs heat, the moisture on the surface of the particles quickly vaporizes, and the outer surface of the particles is instantly dried to the expected moisture content. Along with the vaporization of moisture, the volume of the sprayed material expands rapidly, and the particles in the middle part are driven by the inner parallel airflow to quickly move away from the injection point and enter the lower end of the inner parallel airflow, where the temperature is lower than the injection point. Here, the particles continue to be dried at a sub-high temperature to further dry the inside of the particles, avoid hardening or coking of the outer surface of the particles, and ensure the quality of the dried particles. The particles on the peripheral side enter the annular parallel airflow under the impetus of the expansion of the airflow, and the inside of the particles is also further dried in the annular parallel airflow to avoid hardening or coking of the outer surface of the particles, and ensure the quality of the dried particles; and in the process of the particles falling in the annular parallel airflow, due to the fast flow rate of the inner parallel airflow, the particles that are fully dried in the annular parallel airflow return to the inner parallel airflow under the action of pressure, thereby avoiding the temperature of the particles adhering to the inner wall.

[0057] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A multi-element hot air spray drying method, characterized in that: The following steps are included: S1, forming internal parallel airflow in a dry working environment; S2, multiple annular parallel airflows are arranged outside the inner parallel airflow, the airflow directions of the multiple annular parallel airflows are parallel to the inner parallel airflow, the temperature of the inner parallel airflow is higher than that of the annular parallel airflow, the temperature of the multiple annular parallel airflows gradually increases from the outside to the inside, the flow velocity of the inner parallel airflow is higher than that of the annular parallel airflow, and the flow velocity of the multiple annular parallel airflows gradually increases from the outside to the inside; S3, spraying materials by pressure atomization in the inner parallel airflow; A multi-element hot air spray drying machine for a multi-element hot air spray drying method comprises a drying tank (1), wherein a drying chamber (2) is provided in the drying tank (1), an outer channel (3) for introducing a low-flow rate and sub-high-temperature airflow into the drying chamber (2) is arranged at the top of the drying tank (1), an inner channel (4) for introducing a high-flow rate and high-temperature airflow into the drying chamber (2) is arranged in the outer channel (3), and an atomizing device (5) is installed in the drying chamber (2) at a position corresponding to the inner channel (4).

2. A multi-element hot air spray drying method according to claim 1, characterized in that: A rectifying plate (6) for rectifying airflow into parallel airflow is provided in one end of the outer channel (3) and the inner channel (4) close to the drying tank (1).

3. A multi-element hot air spray drying method according to claim 1 or 2, characterized in that: A partition (7) is provided on one side of the atomizing device (5) in the drying chamber (2), an upper discharge channel (8) for discharging materials is formed between the partition (7) and the inner wall of the drying chamber (2), and a cyclone separation device connected to the upper discharge channel (8) is provided on the side wall of the drying tank (1).

4. A multi-element hot air spray drying method according to claim 3, characterized in that: An isolation plate (9) is installed in the upper discharge channel (8), and a lower discharge channel (10) is formed between the isolation plate (9) and the inner wall of the drying chamber (2), the entrance height of the lower discharge channel (10) is lower than the entrance height of the upper discharge channel (8), and the cyclone separation device is connected to the lower discharge channel (10); a porous plate (11) is provided at the bottom of the drying tank (1), and a dehumidification warm air channel (12) is provided below the porous plate (11).

5. A multi-element hot air spray drying method according to claim 4, characterized in that: The height of one side of the porous plate (11) close to the inlet of the lower discharge channel (10) is lower than that of the other side.

6. A multi-element hot air spray drying method according to claim 5, characterized in that: A dehumidifying cold air channel (13) is provided below the porous plate (11) at a position corresponding to the entrance of the lower discharge channel (10).

7. A multi-element hot air spray drying method according to claim 4, characterized in that: The cyclone separation device comprises a secondary cyclone separator (14) and a primary cyclone separator (15) connected to an upper interface of the secondary cyclone separator (14); a feed port of the primary cyclone separator (15) is connected to the upper discharge channel (8); and the secondary cyclone separator (14) is connected to the lower discharge channel (10).

8. The multi-element hot air spray drying method according to claim 4, characterized in that: A first spray head (16) is installed on the top of the drying chamber (2), a second spray head (17) is installed in the upper discharge channel (8), and a third spray head (18) is installed in the lower discharge channel (10).

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