Electric heating blast drying ovens
are specially designed for drying heat-sensitive, decomposable and oxidizing substances. When working, the internal air can be evacuated to a vacuum state or close to a vacuum state, so that the internal air pressure is greatly reduced, thereby changing the boiling point of the moisture of the wet material, and through other methods, such as adding water circulation heating or electric heating, etc. Dry equipment.
What is the drying process of the vacuum drying oven?
1. Three stages of material drying:
Stage 1: Rapid evaporation of nutrients The condition of the material varies from viscous to very viscous. Under the vacuum condition, the heat transfer in the material is intense, and the nutrients evaporate rapidly. At this stage, more than half of the nutrients are evaporated, and the time is very short.
Stage 2: From liquid to solid Material conditions range from very viscous to fully solidified. At this stage, the heat transfer in the material gradually weakens, and the process is not rapid, and the upper and lower soil cladding layers exposed earlier will greatly affect the drying speed.
Stage 3: the process of solid-state drying of the material The material is slowly dehydrated to a block with standard moisture content. This stage evaporates very little nutrients and dries a little faster than the second stage.
2. The relationship between each stage and the degree of vacuum:
Stage 1: the heat exchange process is ideal, the higher the vacuum degree, the faster the nutrient evaporation;
Stage 2: with the weakening of convection and the increase of thermal resistance, the water content will be less and less. If the power of the suction machine is kept unchanged, the vacuum degree will become larger and larger, the convection will become weaker and the drying rate will increase. come lower. If the stirring vacuum is used, the vacuum and convection heat transfer are properly adjusted to the optimal joint, and the speed may be higher.
Stage 3: because the moisture content is small, it may be more suitable for the vacuum degree to be smaller. The drying process is faster if heated with dry hot air.
What is the difference between a vacuum drying oven and an ordinary drying oven?
Scope of application
Blast drying oven laboratory
is widely used in biochemistry, chemical pharmacy, sanitation, agricultural scientific research, environmental protection, and other application fields. It is only used for powder drying, baking, and disinfection of various glass containers. It is especially suitable for fast drying of heat-sensitive, easily decomposed, easily oxidized substances and articles with complex components.
Structure and working principle
The working principle behind the operation of a vacuum drying oven involves the use of a vacuum pump to significantly reduce the ambient pressure to lower the boiling point of the liquid in the substance. A significant reduction in the boiling point increases the rate of evaporation of the liquid and therefore the rate of drying of the substance. In addition, lowering the boiling point suggests that the operating temperature may be much lower compared to conventional air ovens. Thus, heat-sensitive substances can be dried with minimal impact on their physical or chemical properties. In addition, the lack of air (or oxygen) during drying significantly reduces the chances of material oxidizing.
Advantages of vacuum technology drying
Compared with the conventional drying technology, the vacuum drying technology reduces the boiling point of the liquid and shortens the drying time; and various mechanical parts with complex structures are cleaned and then vacuum dried, leaving no residue after drying.
What are the main applications of vacuum drying ovens?
1. Food processing
An important development trend in food processing technology is how to keep the nutrients, color, aroma, and flavor of the food during the drying process. The use of different drying technologies has a great impact on the drying process of food. Usually, a vacuum drying box is used as the drying equipment. It is easier than the traditional drying technology to ensure that the loss of nutrients, color, and flavor is minimized. Because in the vacuum state, the oxygen content is very low. In this case, some aerobic bacteria in the food can be easily killed, and it can also prevent the deterioration of the food caused by oxygen. The use of vacuum drying technology can Get better food quality.
2. Metal products industry
The test that the metal products industry needs to do is high-temperature drying, but even if the ordinary drying oven can be dried, it cannot prevent the oxidation reaction with the oxygen in the air due to high temperature, and the vacuum drying oven is due to the vacuum pump evacuating the air. , no matter how high the temperature will not be oxidized.
3. Recyclable resource industry
In the recyclable resource industry, such as materials containing alcohol and ethanol, it will be dangerous if an ordinary drying oven is used; because alcohol and hexanol are flammable gases, they are prone to danger when they come into contact with dry air, and they are not easy to recover. The vacuum drying oven is ethanol that is in a vacuum environment and is not easy to contact with air, which reduces the risk of production. At the same time, the vacuum equipment is good sealing equipment, and its characteristics can be used for recycling.