The principle of the rotary flash dryer can be divided into three parts according to the function played in the drying process: the bottom part is the fluidization section, the middle part is the dry operation section, and the upper part is the classification section. The structure of each segment is different and the function is different. We initially analyze it:
(1) The fluidization section is the lower part of the material inlet and has a stirrer inside. It can help break up the highly viscous material and make the wet material fully contact with the dry hot air to produce a large heat transfer coefficient. The dry hot air enters the annular channel at the bottom of the dryer from a tangential direction at a certain wind speed, and enters the fluidization section from the bottom of the shell. As the cross section of the passage is suddenly reduced, the kinetic energy is increased and the wind speed is increased, so that a rotating wind field having a large wind speed is formed in the device. After the material enters the dryer from the screw conveyor, it is first subjected to the mechanical pulverization of the agitator. Under the action of centrifugation, shearing and collision, the material is micro-materialized, and fully contacted with the rotating hot air to form a fluidized bed and fluidized. The surface of the particles in the fluidized state is completely exposed to the hot air, colliding with each other and rubbing, and the water evaporates, so that the viscous force between the particles is weakened, and the particles are dispersed and irregularly moved, so that the gas-solid two phases are in full contact. Accelerated mass transfer and heat transfer. In the fluidized section, the temperature difference between the hot and cold medium is large, and most of the water is evaporated in this area. Only the sufficiently dried particles can be taken out of the fluidized section by the hot air. The fluidization section belongs to the high temperature zone, and the moisture content of the material is large. When the material water is dispersed, it has completely separated from the high temperature zone and enters the drying section. Because the inside of the fluidized section material particles maintain a certain amount of moisture, the material will not overheat. The dried particles are momentarily separated from the high temperature zone, so the rotary flash drying equipment is very suitable for heat sensitive materials. After drying in the fluidized section, the material is crushed and dried into spherical and irregular particles with different particle sizes. Under the action of the buoyancy and radial centrifugal force of the rotating air, the undried particles move toward the wall under the action of large centrifugal force. Repeated fluidized drying due to the larger settling velocity and falling back: the smaller particles go up into the drying section.
(2) The drying section is the space between the feeding screw and the classifier, and the material continues to dry in the rotating wind field. The smaller particles continue upwards into the staging section; the larger particles move upwards around the wall and collide with the classifier to dry again until the dry quality requirement is reached. After the hot air in the drying section passes through the fluidized section heat exchange, the wind speed is reduced and the humidity is increased, which ensures that the drying section is smoothly carried out under stable conditions, and the residence time of the material in the dryer is controlled, according to the residence time of the air in the dryer. By adjusting the air flow rate, the particle size, yield, and final moisture content of the finished product are controlled to create a balance between the feed rate and the desired dry product yield in the dryer. The water content of the rotary flash dryer zui end product is rarely affected by fluctuations in the feed moisture content, which is one of the advantages of the dryer.
(3) The grading section is the upper part of the classifier including the classifier. The classifier is an open-hole circular baffle. By changing the hole diameter and the height of the grading section, the air flow rate can be changed to control the particle size and quantity leaving the dryer. . After the drying is completed in this section, the material that meets the particle size requirements is taken out with the hot air and enters the dust collector for supplementation.
Characteristics and application characteristics of rotary flash dryer (1) The material is crushed, dispersed, dried and graded in the dryer at the same time, which enhances mass transfer, heat transfer and high drying strength.
(2) The tangential speed is high, and the contact time between the material and the air is short, which solves the problem of coking discoloration of the heat sensitive material.
(3) Set the classifier to control the particle size and humidity of the product.
(4) The drying gas enters the dryer to generate a strong swirling airflow, which has a strong scouring effect on the material on the wall of the dryer, and can eliminate the sticking phenomenon.
(5) The structure is simple, easy to manufacture and install, and the investment is small.
(6) The hot air is in fluid contact with the material, the heat exchange is even and sufficient, the heat efficiency is high, and the energy saving effect is good.
The rotary flash dryer is an ideal equipment for processing filter cakes, paste-like materials, thixotropic materials, heat sensitive materials, granules and powder materials. It is very popular in dyes, pharmaceuticals, pesticides, fine chemicals, chemical fiber, petroleum and food industries. Broad application prospects.
(1) The fluidization section is the lower part of the material inlet and has a stirrer inside. It can help break up the highly viscous material and make the wet material fully contact with the dry hot air to produce a large heat transfer coefficient. The dry hot air enters the annular channel at the bottom of the dryer from a tangential direction at a certain wind speed, and enters the fluidization section from the bottom of the shell. As the cross section of the passage is suddenly reduced, the kinetic energy is increased and the wind speed is increased, so that a rotating wind field having a large wind speed is formed in the device. After the material enters the dryer from the screw conveyor, it is first subjected to the mechanical pulverization of the agitator. Under the action of centrifugation, shearing and collision, the material is micro-materialized, and fully contacted with the rotating hot air to form a fluidized bed and fluidized. The surface of the particles in the fluidized state is completely exposed to the hot air, colliding with each other and rubbing, and the water evaporates, so that the viscous force between the particles is weakened, and the particles are dispersed and irregularly moved, so that the gas-solid two phases are in full contact. Accelerated mass transfer and heat transfer. In the fluidized section, the temperature difference between the hot and cold medium is large, and most of the water is evaporated in this area. Only the sufficiently dried particles can be taken out of the fluidized section by the hot air. The fluidization section belongs to the high temperature zone, and the moisture content of the material is large. When the material water is dispersed, it has completely separated from the high temperature zone and enters the drying section. Because the inside of the fluidized section material particles maintain a certain amount of moisture, the material will not overheat. The dried particles are momentarily separated from the high temperature zone, so the rotary flash drying equipment is very suitable for heat sensitive materials. After drying in the fluidized section, the material is crushed and dried into spherical and irregular particles with different particle sizes. Under the action of the buoyancy and radial centrifugal force of the rotating air, the undried particles move toward the wall under the action of large centrifugal force. Repeated fluidized drying due to the larger settling velocity and falling back: the smaller particles go up into the drying section.
(2) The drying section is the space between the feeding screw and the classifier, and the material continues to dry in the rotating wind field. The smaller particles continue upwards into the staging section; the larger particles move upwards around the wall and collide with the classifier to dry again until the dry quality requirement is reached. After the hot air in the drying section passes through the fluidized section heat exchange, the wind speed is reduced and the humidity is increased, which ensures that the drying section is smoothly carried out under stable conditions, and the residence time of the material in the dryer is controlled, according to the residence time of the air in the dryer. By adjusting the air flow rate, the particle size, yield, and final moisture content of the finished product are controlled to create a balance between the feed rate and the desired dry product yield in the dryer. The water content of the rotary flash dryer zui end product is rarely affected by fluctuations in the feed moisture content, which is one of the advantages of the dryer.
(3) The grading section is the upper part of the classifier including the classifier. The classifier is an open-hole circular baffle. By changing the hole diameter and the height of the grading section, the air flow rate can be changed to control the particle size and quantity leaving the dryer. . After the drying is completed in this section, the material that meets the particle size requirements is taken out with the hot air and enters the dust collector for supplementation.
Characteristics and application characteristics of rotary flash dryer (1) The material is crushed, dispersed, dried and graded in the dryer at the same time, which enhances mass transfer, heat transfer and high drying strength.
(2) The tangential speed is high, and the contact time between the material and the air is short, which solves the problem of coking discoloration of the heat sensitive material.
(3) Set the classifier to control the particle size and humidity of the product.
(4) The drying gas enters the dryer to generate a strong swirling airflow, which has a strong scouring effect on the material on the wall of the dryer, and can eliminate the sticking phenomenon.
(5) The structure is simple, easy to manufacture and install, and the investment is small.
(6) The hot air is in fluid contact with the material, the heat exchange is even and sufficient, the heat efficiency is high, and the energy saving effect is good.
The rotary flash dryer is an ideal equipment for processing filter cakes, paste-like materials, thixotropic materials, heat sensitive materials, granules and powder materials. It is very popular in dyes, pharmaceuticals, pesticides, fine chemicals, chemical fiber, petroleum and food industries. Broad application prospects.
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