Four ring pilot freeze dryerThe core is to remove material moisture in a low-temperature and low-pressure environment through three steps of "freezing sublimation analysis", while retaining its original composition and properties. It is suitable for laboratory pilot and small-scale production scenarios, and the specific principle is as follows:
1. Preprocessing: Material freezing
First, place the materials to be dried (such as biological agents, food, chemical samples, etc.) into the freeze-drying chamber, and quickly cool them down through the equipment's refrigeration system (compressor+refrigerant), so that all the free water and bound water in the materials are frozen into solid ice. The freezing temperature is usually between -40 ℃ and -60 ℃ (adjusted according to the characteristics of the materials).
Key function: To prevent component damage and morphological deformation caused by moisture evaporation during subsequent drying of materials.
2. Core Step 1: Sublimation Drying (Main Drying)
After the material is frozen, start the vacuum system (vacuum pump) of the equipment to reduce the pressure inside the freeze-drying chamber to an extremely low level (far below atmospheric pressure). At this point, solid ice does not melt into water, but directly skips the liquid phase and sublimates into water vapor (this process is called "sublimation").
Energy supply: Provide a small amount of heat through a heating system (such as shelf heating) to meet the energy required for ice sublimation, while strictly controlling the temperature to avoid material thawing.
3. Core Step 2: Analyze Drying (Secondary Drying)
After sublimation drying, there is still a small amount of bound water (about 5%~10%) adsorbed on the solid surface in the material. Continue to maintain the vacuum environment, increase the shelf temperature appropriately, and resolve these residual moisture into water vapor.
Key objective: To further reduce the moisture content of the material (usually ≤ 1%), extend the shelf life of the product, and avoid subsequent moisture absorption and deterioration.
4. Water collection and discharge
The water vapor generated by sublimation and analysis will be captured by the device's water trap (cold trap) - the temperature of the water trap is lower than that of the freeze-drying chamber (about -60 ℃~-80 ℃), and the water vapor condenses directly into solid ice when it cools, adhering to the inner wall of the water trap. After the drying is completed, stop the machine and raise the temperature. The ice melts into water and is discharged, or the solid ice is directly cleaned to complete the drying cycle.
Core Logic Summary
Low temperature environment → material freezing → vacuum environment → direct sublimation of ice into water vapor → cold trap capturing water vapor → material drying (retaining original properties), mild throughout the process, suitable for pilot scale drying treatment of heat sensitive and easily oxidizable materials.