|Microwave vacuum dryer is mainly used in high value-added, and heat-sensitive agricultural and sideline products, health products, food, herbs, fruits and vegetables, chemical raw materials such as dehydration and drying; low temperature concentration for chemical products, the removal of water of crystallization, the enzyme drying agents; vacuum extraction of Chinese herbal medicine; applicable in the laboratory of the research institutions.
Microwave Vacuum Dryer has the following characteristics:
1, the quality of microwave vacuum dryer: active ingredients at low temperatures, not easily broken down, destroyed, but also the effectiveness of disinfection, sterilization, and to extend shelf life;
Can deliver high viscosity and contain the gas and solid particles or fiber media, but also conveying a variety of corrosive media;
3, the microwave vacuum dryer is easy to control: Microwave occurrence of the vacuum degree of adjustment can be controlled by the PLC programming, external equipped with a dedicated endoscopy, we can observe the whole process of dry;
4, the microwave vacuum dryer energy consumption economy, the high degree of automation.
5, according to the requirements of users crushing;
6, the high efficiency of microwave vacuum dryer: their production efficiency for conventional dry four times;
7, the thermal distribution of microwave vacuum dryer: microwave selective heating of the water molecules, the material internal moisture, heat from the inside out, and water diffusion in the same direction and the temperature difference between inside and outside the small, does not appear conventional dry heat distribution The unevenness of the phenomenon;
Wood vacuum drying wood stacked in a sealed container below the atmospheric pressure conditions, the dry method. Under vacuum, the boiling point of water to reduce evaporation speed, which can speed up the drying rate of wood at a lower temperature. Since the mid-1970s, vacuum drying method gradually promotion in the European timber industry. More in-depth studies, such as Italy, Germany, France and so the timber vacuum drying, and complete sets of equipment for sale. China from the early 1980s began to study and promote the application of wood vacuum drying method, and the development of wood vacuum drying equipment, but also from abroad, mainly for dry and hard hardwood furniture industry.
Wood during the drying process, on the one hand, the surface water evaporation to the ambient air; the other hand, the internal moisture to the surface move. Under normal circumstances, the wood surface moisture evaporation rate is much faster than the speed of movement of the internal water timber. So to speed up the drying rate, must find ways to speed up the movement speed of the internal water timber. Various factors affecting the moving speed of the internal water timber, the pressure of the surrounding air is the decisive factor. If the air temperature and humidity remain unchanged, the timber of water moving speed increases rapidly with the decrease of air pressure, as shown in Figure 2-14. In addition, under vacuum, the boiling point of water is reduced, caused by the wood surface of the water evaporates faster the wood surface and internal moisture gradient increases. And intense wood surface moisture evaporation at the same time, to absorb a large amount of heat of vaporization, causing cooling of the surface of the wood makes the wood surface and the internal temperature gradient to increase. These factors have accelerated the move to the surface of the internal water timber.
Under vacuum, the drying device, air is rare, and not the usual heating method. To solve the heating problem of the vacuum drying of timber, usually three kinds of approach:
(1) intermittently interrupt the vacuum, at atmospheric pressure and convection heating - intermittent vacuum drying;
(2) continuous contact with the heating metal plate - continuous vacuum drying;
(3) high-frequency current heating - high-frequency vacuum for drying.
In the growing market of wood products, will become more and more demand for wood drying, not only the drying quality also consider drying costs, impact on the environment. I believe that the near few years, environmentally friendly wood drying equipment will mature technology to replace conventional drying!