Vacuum freeze-drying technology has a wide range of applications in the fields of bioengineering, pharmaceutical industry, food industry, material science, and deep processing of agricultural and sideline products. At present, there are so many kinds of freeze dryers, so users usually do not know how to make a choice. Next, I will introduce the specific classification of the freeze dryer:
I. According to the structure
1. Bell-type freeze dryer:
The freeze-drying chamber and the cold trap are separate upper and lower structures, and the freeze-drying chamber has no pre-freezing function. This type of freeze dryer requires manual operation to transfer the material from the pre-freezing chamber to the freeze-drying chamber when it comes to the drying process after pre-freezing. Most of the laboratory freeze dryers are of the bell type. Compared with the industrial freeze dryers, their structure is simpler and the cost is low. The freeze-drying chamber uses a transparent organic glass cover, which is convenient for observing the freeze-drying situation of the materials.
2. In-situ freeze dryer:
The freeze-drying chamber and the cold trap are two independent chambers. The shelf in the freeze-drying chamber has refrigeration function. After the materials are placed in the freeze-drying chamber, the pre-freezing and drying process of the materials does not require manual operation. The production process of this type of freeze dryer is complicated and the manufacturing cost is high. However, the in-situ freeze dryer is the development direction, which is an ideal choice for exploring the freeze drying process. It is especially suitable for freeze-drying of medicines, biological products and other special products.
II. According to the functions
1. Ordinary shelf freezer dyer:
The materials are placed in the material tray in bulk, and it is suitable for freeze-drying of food, Chinese herbal medicine and powder materials.
2. Top press freeze dryer:
It is suitable for the drying of vial bottled materials. When preparing for freeze drying, dispense the material into vials as needed, and freeze-dry it after the cap is closed. After drying, the gland mechanism is operated to press the cap tightly, which can avoid secondary pollution, re-absorb moisture, and is beneficial to long-time storage.
3. Multi-manifold freeze dryer:
Install the flask outside the drying chamber to dry the material spin-frozen on the inner wall of the flask. At this time, the flask is connected to the manifold outside the drying box as a container. The materials in the flask are heated at room temperature. Through the multi-manifold switch device, the flask can be removed or installed at any time according to the need without shutdown.
4. Freeze dryer with pre-freezing function:
During the material pre-freezing process, the cold trap is used as the pre-freezing cavity to pre-freeze the material. During the drying process, the cold trap is used as a water trap to capture the overflowing moisture of the material. For the freeze dryer with pre-freezing function, the pre-freezing and drying of materials in the freeze-drying process are completed on the freeze dryer, which is highly efficient and saves the cost of a low-temperature refrigerator.
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