Introduction to the drying of wet materials
2021-09-23 17:18:30
In modern society, drying has become an indispensable process in many production fields, so the choice of drying equipment has a direct impact on the drying effect. While the company pursues savings in production efficiency, production costs, energy consumption, etc., a suitable drying method and a high-quality drying equipment can achieve this effect. So what is the drying of wet materials?
1. The drying process of the wet material is carried out under the conditions of the flow rate, humidity and temperature of the drying medium (usually hot air).
When hot air flows stably from the surface of the wet material, because the temperature of the air is high and the temperature of the material is low, there is a heat transfer driving force between the air and the material, and the air transfers the heat to the material in a convection manner, and the material is accepted. This heat is used to vaporize the water and is constantly carried away by the air stream, while the moisture content of the material is continuously decreasing. The drying process ends when the moisture content of the material drops to equilibrium moisture.
During the drying process of the material, there are two mutual processes of heat transfer and mass transfer. The so-called heat transfer is the transfer of heat to the material by the hot air, which is used to vaporize the water and heat the material. The mass transfer is the evaporation of the water in the material. Move to hot air to gradually reduce the moisture of the material and get dry.
2, the characteristics of the drying process in the drying process, because the material always has a certain geometric size, even a very fine powder, from the micro can also be seen as a certain size of the particles, in fact, the above heat transfer The quality process is different between the hot gas flow and the material particles and the material particles. In the theory of drying, the heat and mass transfer process is divided into the heat and mass transfer process of the hot gas flow and the material surface and the internal transfer of the material. Heat mass transfer process. Because the two processes affect the drying process of the materials, the two play different leading and restraining effects in different drying stages, which leads to the faster and stable of the previous stage when the general wet materials are dry. The speed is carried out, while the latter stage is carried out at a slower and slower speed, so we divide the drying process into a constant-speed drying stage and a slow-down drying stage.
1. The drying process of the wet material is carried out under the conditions of the flow rate, humidity and temperature of the drying medium (usually hot air).
When hot air flows stably from the surface of the wet material, because the temperature of the air is high and the temperature of the material is low, there is a heat transfer driving force between the air and the material, and the air transfers the heat to the material in a convection manner, and the material is accepted. This heat is used to vaporize the water and is constantly carried away by the air stream, while the moisture content of the material is continuously decreasing. The drying process ends when the moisture content of the material drops to equilibrium moisture.
During the drying process of the material, there are two mutual processes of heat transfer and mass transfer. The so-called heat transfer is the transfer of heat to the material by the hot air, which is used to vaporize the water and heat the material. The mass transfer is the evaporation of the water in the material. Move to hot air to gradually reduce the moisture of the material and get dry.
2, the characteristics of the drying process in the drying process, because the material always has a certain geometric size, even a very fine powder, from the micro can also be seen as a certain size of the particles, in fact, the above heat transfer The quality process is different between the hot gas flow and the material particles and the material particles. In the theory of drying, the heat and mass transfer process is divided into the heat and mass transfer process of the hot gas flow and the material surface and the internal transfer of the material. Heat mass transfer process. Because the two processes affect the drying process of the materials, the two play different leading and restraining effects in different drying stages, which leads to the faster and stable of the previous stage when the general wet materials are dry. The speed is carried out, while the latter stage is carried out at a slower and slower speed, so we divide the drying process into a constant-speed drying stage and a slow-down drying stage.
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