(1) Do not put too much desiccant to avoid contaminating the bottom of the crucible.
(2) When moving the dryer, hold it with both hands and press the cover tightly with your thumb.
(3) When opening the dryer, do not lift the cover up. Press the dryer with your left hand and carefully push the cover away with your right hand. The cover can not be fully opened until the cold air enters slowly. The cover must be placed on the table upside down.
(4) Do not put too hot objects into the dryer.
(5) Sometimes, after a hot object is put into the dryer, the air will heat and expand to push up the cover. In order to prevent the cover from being overturned, press it with your hand and push the cover away slightly from time to time.
(6) The crucible and precipitation after burning or drying should not be placed in the dryer for too long, otherwise the quality will increase slightly due to absorbing some water.
(7) Discolored silica gel is blue when dry and pink when wet. The moistened silica gel can be dried at 120 ℃ and reused after it turns blue until it is broken and can not be used.
The drying process needs to consume a lot of heat energy. In order to save energy, some materials with high moisture content, suspensions or solutions containing solid substances are generally mechanically dehydrated or heated and evaporated, and then dried in the dryer to obtain dry solids .
The purpose of drying is to meet the needs of material use or further processing. For example, the drying of wood before making wood molds and woodwork can prevent the deformation of products, and the drying of ceramic blank before calcination can prevent the cracking of finished products. In addition, the dried materials are also convenient for transportation and storage, such as drying the harvested grain below a certain moisture content to prevent mildew. Because natural drying is far from meeting the needs of production development, various mechanized dryers are more and more widely used.
During the drying process, heat and mass (wet fraction) transfer shall be completed at the same time to ensure that the wet fraction steam partial pressure (concentration) on the material surface is higher than that in the external space, and the heat source temperature is higher than the material temperature.
Heat is transferred from the high-temperature heat source to the wet material in various ways, so that the moisture on the material surface vaporizes and escapes to the external space, resulting in the difference of moisture content on the material surface and inside. The internal moisture content diffuses to the surface and vaporizes, so as to continuously reduce the moisture content of the material,
Gradually complete the overall drying of materials.
The drying rate of materials depends on the surface vaporization rate and the diffusion rate of internal moisture. Generally, the drying rate in the early stage of drying is controlled by the surface evaporation rate; Then, as long as the external drying conditions remain unchanged, the drying rate and surface temperature of the material remain stable. This stage is called constant speed drying stage; When the moisture content of the material decreases to a certain extent, the diffusion rate of the internal moisture to the surface decreases and is less than the surface vaporization rate, the drying rate is mainly determined by the internal diffusion rate and decreases continuously with the decrease of the moisture content. This stage is called the speed reduction drying stage