What is drying? The principles and characteristics of spray drying and freeze drying?
Drying usually refers to the process of vaporizing the moisture (or solvent) in the material by thermal energy, and the generated steam is taken away by the inert gas. Airflow drying refers to the operation of using high-speed hot airflow to dry the material during the fluidized transportation .
The characteristics of spray drying are:
1. The spray drying heat transfer effect is good.
2. Spray drying increases the average temperature difference between gas and solid.
3. The spray drying equipment has a simple structure, is easy to manufacture, has a small footprint, can be operated continuously, and is suitable for automatic control.
4. Widely applicable. It can be applied to the drying of all kinds of powdery granules and sludge.
Spray drying refers to the process of drying highly dispersed solutions or suspensions by connecting with hot air. It is particularly suitable for bioengineering products that cannot be obtained by crystallization.
The advantages of spray drying:
(1) The drying process proceeds quickly
(2) The temperature of the material is low during the drying process
(3) The powder can be obtained directly from the liquid material, eliminating the steps of evaporation, crystallization, separation and crushing, and can be operated under semi-sterile conditions. (4) The quality of the finished product can be controlled.
Disadvantages of spray drying:
(1) The volume of spray drying is low in drying strength, so the volume of the drying chamber is large
(2) The energy consumption of spray drying is large, the amount of drying medium is large, and the use of heat is not economical
(3) The product will stick to the wall.
Freeze-drying, also known as sublimation drying, is a drying process that freezes wet materials or solutions into a solid state at a relatively low temperature (-10 to -50 ° C), and then directly sublimates the water into a gaseous state without sublimation under high vacuum . Its main advantages are:
(1) The operating temperature is low, and the dried material maintains the original chemical composition and physical properties (such as porous structure, colloidal properties, etc.);
(2) The calorie consumption is less than other drying methods. The disadvantage is that the cost is higher and can not be widely used. Used for drying antibiotics, vegetables and fruits.
The above information is a summary of the editor of Shanghai Bilang Instrument Manufacturing Co., Ltd., and you are also welcome to Baidu search Shanghai Bilang Mall for more instrument details!
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