Air flow drying device with spraying feeding function

Abstract

The invention relates to the technical field of pneumatic drying devices, and discloses a spray feeding pneumatic drying device which comprises an evaporation tower, an air inlet fan, a heat exchanger and a gas filter, one end of the gas filter is connected with the bottom of the evaporation tower through a pipeline, and the top of the evaporation tower is connected with a spiral pipeline with heat tracing through a pipeline. Spraying and feeding assemblies are installed in the middle and on the lower portion of the evaporation tower, an air inlet device is arranged between the gas filter and the evaporation tower, pore plates are arranged on the lower portion and the conical wall of the barrel wall, and it is ensured that even if the inner space of equipment is narrow, the inner space of the equipment is not large, and the equipment cannot be damaged. Compared with a conventional cylinder, the spiral pipe with the heat tracing function has the advantages that the passage stroke can be greatly increased under the same occupied volume, and meanwhile, the reliability of the drying effect of the equipment is remarkably improved due to efficient continuous direct contact wall heat extraction obtained by circular motion.

Description

Technical Field

[0001] This invention relates to the field of airflow drying equipment technology, specifically to an airflow drying equipment with spray feeding. Background Technology

[0002] Airflow drying is widely used in various industries. The main method is to continuously feed solid materials into the bottom of the cylinder equipment, crush them with high speed, and continuously introduce a large amount of hot air to blow up and suspend the crushed materials. The dried powder particles are blown upward out of the cylinder by the airflow and then enter the gas-solid separation equipment to obtain dried powder products.

[0003] For heat-sensitive materials in solution and fine powder slurry form, spray drying is conventionally used because smaller droplets can dry to the appropriate moisture content more quickly. However, unlike the usual airflow drying which blows air from bottom to top, conventional spray drying equipment blows air and sprays from top to bottom. The droplets, along with the external hot airflow from top to bottom, reach the bottom of the spray drying tower. Part of the powder obtained by the droplet drying falls to the bottom of the tower, while the rest flows out from the bottom of the tower with the airflow and enters the gas-solid separation equipment to obtain the powder product.

[0004] However, the high-speed, divergent fine droplets produced by various spraying methods have a large initial velocity. When the diameter or height of the spray tower is not large enough, or when the airflow temperature cannot be high due to the heat sensitivity of the material, a large number of droplets may collide with the inner wall of the equipment before the surface is dry, thus adhering and accumulating on the inner wall surface, making it difficult to dry quickly and affecting the quality of the material (for example, polymer monomer materials may undergo polymerization reaction due to prolonged accumulation of wet material). To prevent the high-speed divergent droplets from sticking to the wall, existing spray drying equipment conventionally adopts a relatively large internal space design and a high gas temperature. Such a structure occupies a large workshop area, and the airflow in the large space is difficult to control. The high temperature is not conducive to the quality of the material product.

[0005] Therefore, to address the drying problem of our heat-sensitive slurry, we propose an airflow drying device that combines spray feeding to solve the aforementioned problem. Summary of the Invention

[0006] To address the problems that existing airflow drying or spray drying equipment may cause undried material particles to collide and accumulate on the walls, or some material to flow out of the drying tower before it has time to dry, resulting in substandard quality, when used for heat-sensitive materials, due to insufficient airflow temperature or insufficient tower inner diameter and / or height. This invention provides an airflow drying device suitable for heat-sensitive materials in the form of solutions and fine powder slurries, which uses a bottom-up hot airflow for spray drying to avoid these problems and obtain qualified products.

[0007] The present invention is achieved by the following technical solution: a spray-feed airflow drying device, comprising an evaporation tower and an air inlet fan, one end of the air inlet fan being connected to a heat exchanger via a pipe, one end of the heat exchanger being connected to a gas filter via a pipe, one end of the gas filter being connected to the bottom of the evaporation tower via a pipe, at least one spray-feed component being installed in the middle and lower parts of the evaporation tower, an air inlet device being provided between the gas filter and the evaporation tower, the air inlet device comprising a first air inlet pipe and a second air inlet pipe, a cone being provided at the bottom of the evaporation tower, one end of the second air inlet pipe penetrating the outer wall of the cone, an air outlet opening and closing component being provided at one end of the first air inlet pipe, and one end of the first air inlet pipe being fixedly connected to the lower part of the evaporation tower; The lower part of the evaporator and the inner wall of the cone are provided with a perforated plate shell. One end of the second air inlet pipe is connected to the space between the evaporator and the perforated plate shell. The top of the evaporator is fixedly connected to a discharge port. One end of the discharge port is fixedly connected to a spiral pipe with heat tracing. One end of the spiral pipe with heat tracing is fixedly connected to a cyclone dust collector.

[0008] Preferably, the air vent opening and closing assembly is located directly below the orifice plate housing. The air vent opening and closing assembly includes a bottom tube and a flip cover. One end of the flip cover is hinged to the top of the bottom tube, and a return spring is provided at the connection between the bottom tube and the flip cover.

[0009] Preferably, one end of each of the two spray feed assemblies penetrates the sidewall of the evaporation tower, the cone, and the orifice plate shell, and the spray nozzle of the spray feed assembly is located at the center of the evaporation tower.

[0010] Preferably, the perforated plate shell is located at the lower part of the evaporator and on the inner wall of the cone, and a heat tracing plate is provided on the outside of the shells of the evaporator, the cone and the cyclone dust collector.

[0011] Preferably, the structure of the heat-traced spiral tube is such that a heat-tracing tank is provided on the outside of the spiral tube, and the spiral tube is immersed in the heat-tracing tank, which is filled with steam or hot water for heating.

[0012] Compared with the prior art, the beneficial effects of the present invention are: When in use, the "air cushion" structure formed by the perforated plate shell of the cylinder wall and the cone wall ensures that even if the internal space of the equipment is narrow, the droplets formed by the spray feed will not hit the wall and adhere.

[0013] In use, the heated spiral tube of this invention, compared to a conventional cylinder, provides a significantly increased travel distance within the same volume. Simultaneously, the powder particles, due to their circular motion, achieve highly efficient and continuous direct "wall-contact heat extraction" (rather than the inefficient heat transfer via parallel gas flow in conventional straight-cylinder equipment). This significantly improves the reliability of the drying process, especially for heat-sensitive materials where temperatures cannot be too high. The relatively longer travel distance and extended drying process within the heated spiral tube are crucial for thorough drying. While surface moisture in the material droplets evaporates quickly, resulting in dehydrated particles, the escape of internal water molecules becomes difficult as the material concentrates and a dehydrated outer shell forms. This means that drying the final small amount of water to achieve the required moisture content may take significantly longer than the initial drying stage. Therefore, in the later stages of material droplet drying, in addition to the continued need for heat energy, the time factor becomes critical. The use of a long-distance heated spiral tube effectively addresses this need.

[0014] In use, this invention, through the introduction of a heated spiral tube with high-efficiency drying effect, ensures better material drying. Therefore, the height and size of conventional straight-cylinder evaporators, which have relatively low drying efficiency, can be significantly reduced. It only needs to ensure that the material droplets at the outlet are surface-dehydrated and do not stick to the walls, rather than requiring the conventional method of achieving the required drying standard. The later drying stage is handled by the more suitable heated spiral tube. That is, the existing straight-cylinder evaporator with a relatively large diameter is used to achieve the functions of material spraying and droplet surface drying, but its height is reduced. The later drying process, which it is less suited to, is handled by the heated spiral tube, which is better suited for later drying. This combination of their respective strengths improves the overall efficiency and effectiveness of the equipment.

[0015] When in use, the air cushion can prevent sticking to the wall, and the long-distance heated spiral tube greatly improves the drying effect. Therefore, the upper and lower spray components can spray simultaneously, which significantly increases the production capacity compared to conventional simple upper or lower spraying.

[0016] When used, this invention achieves the same or better drying capacity and effect. Compared with conventional single tall spray drying equipment that occupies a large workshop floor area, this method's equipment is significantly narrower and extends into the air with fewer restrictions. It adds substantial functional components, thus achieving better results and reducing the workshop floor area. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a sectional view of the lower part of the evaporation tower of the present invention; Figure 3 For the present invention Figure 2 Enlarged diagram of section A in the middle; Figure 4 This is a schematic diagram of the air vent opening and closing component structure of the present invention.

[0018] In the diagram: 1. Evaporation tower; 101. Cone; 2. Inlet fan; 3. Heat exchanger; 4. Gas filter; 5. Inlet device; 501. First inlet pipe; 502. Second inlet pipe; 6. Cyclone dust collector; 7. Spray feeding assembly; 8. Air outlet opening and closing assembly; 801. Bottom pipe; 802. Flip cover; 9. Orifice plate shell; 10. Heat tracing plate; 11. Spiral tube with heat tracing; 12. Discharge port; 13. Heat tracing tank. Detailed Implementation

[0019] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0020] Example 1: Please refer to Figure 1 - Figure 4 This embodiment of a spray-feed airflow drying device includes an evaporation tower 1 and an inlet fan 2. One end of the inlet fan 2 is connected to a heat exchanger 3 via a pipe, and one end of the heat exchanger 3 is connected to a gas filter 4 via a pipe. One end of the gas filter 4 is connected to the bottom of the evaporation tower 1 via a pipe. At least one spray-feed assembly 7 is installed in the middle and lower parts of the evaporation tower 1. An air inlet device 5 is provided between the gas filter 4 and the evaporation tower 1. The air inlet device 5 includes a first air inlet pipe 501 and a second air inlet pipe 502. A cone 101 is provided at the bottom of the evaporation tower 1. One end of the pipe 502 penetrates the outer wall of the cone 101. One end of the first air inlet pipe 501 is provided with an air outlet opening and closing assembly 8. One end of the first air inlet pipe 501 is fixedly connected to the lower part of the evaporation tower 1. The lower part of the evaporation tower 1 and the inner wall of the cone 101 are provided with a perforated plate shell 9. One end of the second air inlet pipe 502 is connected to the space between the evaporation tower 1 and the perforated plate shell 9. The top of the evaporation tower 1 is fixedly connected to the discharge port 12. One end of the discharge port 12 is fixedly connected to a spiral pipe 11 with heat tracing. One end of the outlet of the spiral pipe 11 with heat tracing is fixedly connected to the cyclone dust collector 6. The gas filter 4 can be a bag filter, the heat exchanger 3 is a high-path dust collector to reduce the floor space, and the cyclone dust collector 6 collects most of the products; the clean hot airflow output from the gas filter 4 enters the evaporator 1 through the air inlet device 5 in two paths: the second air inlet pipe 502 penetrates the outer wall of the cone 101 and is connected to the lower part of the evaporator 1 and the annular space between the cone 101 and the orifice plate shell 9, providing the air source for the "air cushion" structure; the first air inlet pipe 501 is fixedly connected to the lower part of the evaporator 1, and the cone 101 at the bottom of the evaporator 1 adopts a gradually tapering design to ensure that a stable airflow field is formed when the airflow rises, lifting the material particles to prevent them from settling; In this system, the drying gas enters from the bottom of the evaporator 1 and exits from the top. The lower part of the evaporator 1 is equipped with a gradually narrowing cone 101. The lower part of the evaporator 1 and the inner wall of the cone 101 are provided with perforated plate shells 9, allowing the hot gas for supplemental drying to enter the evaporator 1 and form an air cushion to prevent material droplets from hitting and adhering to the walls. The cone 101 is long enough and the lower opening is small enough so that during normal ventilation, the largest material spray particles or the largest solid particles formed by them in the evaporator 1 can be lifted by the airflow. The cone 101 has an air inlet device 5 at its lower opening and an air vent opening and closing assembly 8 at its upper part. During normal ventilation, the gas can blow up the flip cover 802. However, when the ventilation stops, the flip cover 802 falls down and blocks the bottom pipe 801, allowing any solids inside the cone 101 to fall out of the cone 101 outside the air vent. One end of the discharge port 12 at the top of the evaporator 1 is connected to a heated spiral tube 11, so that the drying process can continue for a sufficient period of time after the material leaves the evaporator 1 and enters the heated spiral tube 11. In a conventional straight pipe channel, the material mainly moves in a parallel flow. After the moisture in the middle of the channel evaporates due to heat absorption, the local temperature drops. If there is no heating structure on the channel wall or inside, the heat energy can only be provided by the heat capacity of the airflow. However, the heat provided by heat capacity alone is very limited, and the temperature will continue to drop, resulting in low drying efficiency (the conventional method is to try to increase the gas temperature at the inlet, but this is limited for heat-sensitive materials). If the wall of this section of the channel is heated, because the flow is basically parallel, the material in the middle can only rely on the heat transfer of the gas to provide heat for continuous moisture evaporation. However, this gas-based heat transfer method is inefficient. But in a spiral tube 11 with heating, all moving matter, including the medium gas and material particles, undergoes circular motion. Since the density of the material particles is significantly greater than that of the gas medium, the material particles will be continuously... The material particles are thrown as far as possible, meaning they are always thrown against the pipe wall. This means that the main movement of the material particles is always along the pipe wall. This means that the material particles can always have direct "contact heat transfer" with the heated pipe wall. The effect of this heat transfer method is much higher than that of indirect heat transfer through air, etc. Moreover, this situation where solid particles directly contact the pipe wall to absorb heat will be uniform even when there are many solid particles. That is, the opportunity to directly contact the pipe wall will be automatically rotated among the particles. For some particles that are "buffered" by other particles and cannot directly contact the pipe wall at a certain moment, they will get the opportunity to directly contact the pipe wall at a later moment due to the rotation and rolling forward (particles that continuously directly contact the wall will lag in movement due to frictional resistance with the pipe wall). Therefore, the overall heating of the material will also be uniform. For heat-sensitive materials where the temperature cannot be too high, the relatively longer travel distance and thus longer heating and drying process in the heated spiral tube 11 is of great significance for the thorough drying of the material. This is because the moisture on the surface of the material droplets can evaporate quickly, immediately resulting in dehydrated particles. However, as the material concentrates and a dehydrated shell forms, the escape of internal water molecules becomes difficult, making the drying of the last small amount of water that meets the moisture index requirements potentially take more time than in the initial drying stage. In other words, in the later stages of material droplet drying, in addition to still requiring a certain amount of heat energy, the time factor becomes very important. The use of a long-distance heated spiral tube better meets this requirement. Furthermore, the air outlet opening and closing assembly 8 is located directly below the orifice plate housing 9. The air outlet opening and closing assembly 8 includes a bottom pipe 801 and a flip cover 802. One end of the flip cover 802 is hinged to the top of the bottom pipe 801. A return spring is provided at the connection between the bottom pipe 801 and the flip cover 802. During normal operation, it supplements the airflow to the lower part of the evaporation tower and enhances the stability of the airflow field. In the case of air stoppage, it prevents incompletely dried material particles in the cone 101 from falling from the bottom pipe 801, avoiding material waste and blockage at the bottom of the equipment. At the same time, it maintains a sealed environment inside the tower, which facilitates the rapid establishment of a stable airflow when the next startup is initiated. Furthermore, one end of each of the two spray feed components 7 penetrates the sidewalls of the evaporation tower 1, the cone 101, and the orifice plate shell 9. The spray nozzle of the spray feed component 7 is located at the center of the evaporation tower 1. When the two spray feed components 7 penetrate the sidewalls of the evaporation tower 1, the cone 101, and the orifice plate shell 9, they are fixed with sealing sleeves to ensure that there is no airflow leakage or material leakage at the connection. The spray nozzle of the spray feed component 7 is precisely positioned at the central axis of the evaporation tower 1. Furthermore, the top of the cyclone dust collector 6 is connected to a lower-level recovery pipe 16, and one end of the lower-level recovery pipe 16 is connected to a lower-level dust collection device. The primary cyclone dust collector 6 can collect most of the dry materials, and the lower-level dust collection device further collects the remaining fine powder materials, which greatly improves the material recovery rate and reduces waste. At the same time, the secondary dust collection system reduces the dust content in the exhaust gas, meets environmental emission standards, and avoids dust pollution of the workshop environment and atmosphere. Furthermore, a heat-traced tank 13 is installed outside the spiral tube 11 with heat tracing. The spiral tube 11 with heat tracing is immersed in the heat-traced tank 13, which is filled with steam or hot water for heating. Other equipment, including the evaporation tower 1 and the cyclone dust collector 6, have heat-traced plates 10 on their outer shells, which are filled with steam or hot water for heat tracing. The heat tracing system ensures that all key parts of the equipment are always in a stable temperature environment: firstly, to avoid moisture condensation caused by localized low temperatures during the drying process, which would affect the drying effect; and secondly, to prevent the dried material from adhering to the inner wall of the evaporation tower 1, ensuring smooth material transportation and collection.

[0021] Working principle: When the air intake fan 2 starts, it delivers ambient temperature air to the heat exchanger 3 and heats it to the set temperature. After passing through the gas filter 4 to remove impurities, it forms a clean hot airflow. The hot airflow is divided into two paths by the air intake device 5. One path enters the lower part of the evaporation tower through the flip cover 802 of the air inlet opening and closing component 8 via the first air intake pipe 501. The other path enters the annular space between the evaporation tower 1 and the perforated plate shell 9 via the second air intake pipe 502, and seeps out through the perforated plate to form an "air cushion". The two spray feeding components 7 spray from the center of the evaporation tower to the surrounding area. The droplets meet the rising hot airflow in the opposite or same direction. The material particles are protected by an "air cushion" to prevent them from hitting the wall, while simultaneously completing surface dehydration quickly to form pre-dried material particles. These pre-dried material particles enter the heated spiral tube 11 through the outlet 12. The material particles move in a circular motion with the airflow, always adhering closely to the tube wall for efficient contact heat transfer, extending the drying process and time, and achieving complete evaporation of internal moisture. The deeply dried material particles enter the cyclone dust collector 6 with the airflow, where most of the material is collected under centrifugal force. The remaining fine powder enters the lower-level dust collection equipment through the lower-level recovery pipe 16 for collection, and the purified gas is discharged from the equipment.

[0022] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A spray-feed airflow drying device, comprising an evaporation tower (1) and an inlet fan (2), a heat exchanger (3), a gas filter (4), a cyclone dust collector (6), and a spray-feed assembly (7), wherein one end of the inlet fan (2) is connected to the heat exchanger (3) via a pipe, one end of the heat exchanger (3) is connected to the gas filter (4) via a pipe, and one end of the gas filter (4) is connected to the bottom of the evaporation tower (1) via a pipe, characterized in that, At least one spray feed assembly (7) is installed in the middle and lower part of the evaporation tower (1). An air inlet device (5) is provided between the gas filter (4) and the evaporation tower (1). The air inlet device (5) includes a first air inlet pipe (501) and a second air inlet pipe (502). A cone (101) is provided at the bottom of the evaporation tower (1). One end of the second air inlet pipe (502) penetrates the outer wall of the cone (101). An air outlet opening and closing assembly (8) is provided at one end of the first air inlet pipe (501). One end of the first air inlet pipe (501) is fixedly connected to the lower part of the evaporation tower (1). The lower part of the evaporator (1) and the inner wall of the cone (101) are provided with a perforated plate shell (9). One end of the second air inlet pipe (502) is connected to the space between the evaporator (1) and the perforated plate shell (9). The top of the evaporator (1) is fixedly connected to a discharge port (12). One end of the discharge port (12) is fixedly connected to a spiral tube (11) with heat tracing. One end of the outlet of the spiral tube (11) with heat tracing is fixedly connected to a cyclone dust collector (6).

2. The spray-feed airflow drying device according to claim 1, characterized in that, The air vent opening and closing assembly (8) is located directly below the orifice plate housing (9). The air vent opening and closing assembly (8) includes a bottom tube (801) and a flip cover (802). One end of the flip cover (802) is hinged to the top of the bottom tube (801). A reset spring is provided at the connection between the bottom tube (801) and the flip cover (802).

3. The spray-feed airflow drying device according to claim 1, characterized in that, One end of each of the two spray feed assemblies (7) penetrates the sidewall of the evaporation tower (1), the cone (101) and the orifice plate shell (9), and the spray nozzle of the spray feed assembly (7) is located at the center of the evaporation tower (1).

4. The spray-feed airflow drying device according to claim 1, characterized in that, The perforated plate shell (9) is located at the lower part of the evaporator (1) and the inner wall of the cone (101). The evaporator (1), the cone (101) and the cyclone dust collector (6) are provided with heat tracing plates (10) on the outside of the shells.

5. The spray-feed airflow drying device according to claim 1, characterized in that, The structure of the heat-traced spiral tube (11) is such that a heat-tracing tank (13) is provided on the outside of the spiral tube, and the spiral tube is immersed in the heat-tracing tank (13), which is filled with steam or hot water for heating.

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