|Many types of vacuum dryer, the drying chamber can most atmospheric dryer closed can realize vacuum drying. In the field of vacuum drying technology, can make the vacuum dryer is divided into ordinary and special vacuum drying, vacuum drying
Ordinary vacuum dryer mainly include: suitable for box dryer liquid, paste, powder and granular materials drying; suitable for fruit juice, milk, molasses, sweet potato, tomato paste, drying drum type vacuum drier; suitable for orange juice, tomato juice, instant tea and instant coffee production of vacuum belt dryer; is suitable for the powder material particles, vacuum dryer vibration flow such as vitamin C and dry; and agitator type vacuum dryer, double cone rotary vacuum dryer, rake vacuum dryer, vacuum drying machine, disc blade.
In a vacuum dryer can realize foam vacuum drying. Liquid material after beating with air or add such as ammonium carbonate, can produce gases. Then by contact heating, in the reduced pressure due to gas expansion, formed by a foam layer vacuum control, dry products with foam layer structure is loose, instant advantages. Therefore, the foam vacuum drying method is often used as a simple method for preparation of instant food: for example, processing malted milk, milk replacer, fruit powder, instant coffee, instant tea and other food. Operation points of foam vacuum drying method is that when the initial drying stage more water and liquid volume viscosity is not high, not easy to operation under high vacuum. Otherwise the foaming uplift foam layer is high, easy to overflow plate, and the bubble rupture, lost should be retained to later gas foaming capacity. When drying the slurry to a certain degree, then improve the vacuum degree, the bubble has a certain degree of stability, not easy to break, the formation of cellular skeleton stable, in order to further drying.
Special vacuum dryer are: vacuum freezing dryer, low vacuum dryer and vacuum dryer.
If you press the vacuum dryer uses division, can be divided into food vacuum dryer, drug vacuum dryer, wood vacuum dryer, vacuum dryer polymer, chemical products such as vacuum dryer.
General Electric (blast) dryer are equipped with temperature uniformity parameters: natural convection dryer for working temperature limit by 3%, dryer forced convection as the working temperature limit by 2.5%. But the electric vacuum dryer without temperature uniformity parameters, is this why?
Vacuum dryer is dependent on gas molecular motion of the studio temperature uniform possibility almost has no.
Therefore, from the concept we wouldn't normally electrothermal (blast) under the dryer temperature uniformity definition of vacuum dryer.
In a vacuum state under this index is of no significance. The amount of heat radiation and inversely as the square of the distance. The same object, distance radiation heat accept heating wall 20cm premises only distance heating wall at 10cm 1/4. Great differences. This kind of phenomenon and the winter sun, sun to the sun is warm, not to bask in the sun side cooler is a truth. Because the vacuum dryer is very difficult in the structure make the studio in three-dimensional space (garden of the spherical) radiation heat evenly, but also the lack of evaluation method of authority, this may be the reason for electric vacuum dryer standard is not provided with the temperature uniformity parameters.