Vacuum dryer advantages and disadvantages and vacuum thermal drying method
The design of the dryer basically adopts large industrial simulation software to simulate the drying process, such as the common spray dryer, flash dryer, etc., they have independently developed fluid simulation software to simulate, so as to ensure that the designed products can meet the requirements of production. Its manufacturing automation level is high, many parts of the dryer are CNC lathe or the robot according to the preset drawing one-time molding.
There are many kinds of vacuum dryers, which are widely used and developed rapidly.
Vacuum dryer drying has many advantages: low oxygen content when drying under low pressure, can prevent the drying materials from oxidative deterioration, can dry flammable and explosive dangerous goods; can vaporize the moisture in the material at low temperature, easy to dry heat sensitive materials; can recover valuable and useful components in the dried materials; can prevent the discharge of toxic and harmful substances in the dried materials Environmental protection type of "green" drying. Therefore, vacuum dryer is widely used.
The main disadvantage of vacuum dryer is that it needs a set of vacuum system that can pump steam, which makes the equipment investment cost high and the operation cost high; the equipment production efficiency is low and the output is small. In order to overcome these shortcomings, many scientific and technological workers have made a lot of efforts. At the same time, because vacuum drying has many advantages, some products have to use vacuum dryer. Therefore, the development of vacuum dryer will have a bright future.
Generally, it is recommended to freeze-drying a large number of wet or moist materials. When entering the vacuum freeze-drying chamber, the materials must be in a frozen state and remain frozen during the whole drying process. In this process, the frozen water is turned into steam instead of passing through the liquid phase, which is beneficial to the emergence and exudation of soluble medium.
It allows the coating material to dry without clogging and causes small deformation. The process can be carried out on site by a supplier equipped with a mobile vacuum chamber, or items can be sent to a drying facility. The drying time depends on the humidity of the material, but can usually be completed in less than two weeks).
After studying the method of vacuum thermal drying, it is suggested to use vacuum thermal drying in humid or humid materials. The materials can be frozen or thawed in the room and dried above 0 ℃. The material is dried in a vacuum chamber with heated air. Generally recommended for uncoated paper, vacuum thermal drying is generally considered to be a cost effective option for low intrinsic value materials. It is known that this method will deform the paper, cause the coating record to be blocked, and aggravate the emergence and color penetration of soluble ink. The drying time is usually shorter than that of vacuum freeze-drying, but this depends on the initial wettability).