The vacuum freeze dryer is suitable for the drying of high-end raw materials, Chinese herbal medicine, biological, wild vegetables, dehydrated vegetables, food, fruits, chemicals, pharmaceutical intermediates and other materials. Freeze vacuum drying is a new type of cabinet structure introduced by the vacuum freeze dryer that combines the refrigeration system, vacuum system, heat transfer oil heating system, and moisture removal system, which makes use of the material storage space in the cabinet for drying.

application

1. The vacuum freeze dryer is suitable for the drying of high-end raw materials, Chinese herbal medicines, seafood, wild vegetables, dehydrated vegetables, food, fruits, chemical drug intermediates and other materials.

2. The vacuum freeze dryer combines the refrigeration system, vacuum system, heat transfer oil heating system, and dehumidification system into one, a new type of cabinet structure, which makes greater use of the material storage space in the cabinet for drying and freeze vacuum drying, which can make it dry after drying The powder has good dispersibility.

Features

The freezing vacuum drying process is that no impurities are mixed into the object, which can keep the original ingredients and active ingredients of the material and the shape of the material intact.

working principle

After starting the machine, put the materials into the material box for freezing. In the freezing process of the materials, on the one hand, the vacuum system vacuums to take away some of the moisture; on the other hand, the moisture in certain molecules is discharged to the The surface of the material is frozen. After reaching the freezing requirement, the heating system will heat and dry the material, and the moisture contained in the material will be taken to the freezing trap box to freeze through the vacuum, so as to meet the material freeze drying requirement.

Freeze drying refers to the process of removing water or other solvents from frozen biological products by sublimation. Sublimation refers to the process by which solvents, such as water, like dry ice, do not go through a liquid state, but change from a solid state to a gas state. The product obtained by freeze drying is called lyophilizer, and this process is called lyophilizer. Traditional drying can cause materials to shrink and destroy cells. The structure of the sample will not be destroyed during the freeze-drying process, because the solid components are supported by the solid ice in its place. When ice sublimates, it leaves pores in the dry residue. This preserves the integrity of the product's biological and chemical structure and its activity. In the laboratory, freeze-drying has many different uses, and it is indispensable in many biochemical and pharmaceutical applications. It is used to obtain biological materials that can be stored for a long time, such as microbial culture, enzymes, blood, and medicines. In addition to long-term storage stability, it also retains its inherent biological activity and structure. For this reason, lyophilization is used to prepare tissue samples for structural studies (such as electron microscopy studies). Freeze drying is also used in chemical analysis. It can obtain dry samples, or concentrate samples to increase the sensitivity of analysis. Lyophilization stabilizes the composition of the sample without changing the chemical composition, making it an ideal analytical aid. Freeze drying can occur naturally. Under natural conditions, this process is slow and unpredictable. Through the freeze-drying system, people have improved and subdivided many steps to speed up the process.

classification

Structurally

Bell-jar type freeze-drying machine: The freeze-drying cavity and cold trap are separate upper and lower structures, and the freeze-drying cavity has no pre-freezing function. This type of freeze dryer requires manual operation when the material is transferred to the drying process after pre-freezing. Most of the experimental freeze dryers are of bell jar type, with simple structure and low cost. Most freeze-drying chambers use transparent organic glass cover, which is convenient for observing the freeze-drying of materials.

In-situ freeze-drying machine: the freeze-drying chamber and the cold trap are two independent chambers. The shelf in the freeze-drying chamber has a refrigeration function. After the material is placed in the freeze-drying chamber, the pre-freezing and drying process of the material 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 of the freeze dryer. It is an ideal choice for exploring the freeze drying process. It is especially suitable for medicine, biological products and other special products. Freeze-dried.

a, ordinary type b, multi-manifold type c, gland type

Functionally

Ordinary shelf type: The materials are packed in bulk in the material tray, which is suitable for freeze-drying food, Chinese herbal medicine and powder materials.

Type with capping device: suitable for drying cillin bottled materials. When preparing for lyophilization, the materials are divided into cillin bottles as needed. After the cap is floated, the cap is frozen and dried. After drying, the capping mechanism is operated to press the cap tightly. , Can avoid secondary pollution, re-absorb water, easy to store for a long time.

Multi-manifold type: Connect the flask outside the drying chamber to dry the material spin-frozen on the inner wall of the bottle. At this time, the flask is connected to the manifold outside the drying box as a container. The material in the flask is heated at room temperature and passes through the multi-manifold. The tube switch device can be removed or installed at any time as needed without stopping the machine.

Type 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 a water trap to capture the overflowing moisture of the material. The freeze-drying machine with pre-freezing function, the pre-freezing and drying of the materials in the freeze-drying process are completed on the freeze-drying machine, the use of the freeze-drying machine is efficient, and the cost of the low-temperature refrigerator is saved.

Optional parameters

1. Freeze-dried area

The number in the freeze dryer model represents the freeze-drying area of ​​the freeze-drying machine of this model, for example, the freeze-drying area of ​​the LGJ-18C freeze-drying machine is 0.18 square meters. Users should determine how much freeze-drying area the freeze-drying machine needs by calculation according to their own needs. For example, each batch of products that needs to be freeze-dried 1.8 kilograms (liters) of liquid, and the material tray is loaded with materials, and each tray is loaded with 10 mm thickness, then the load area of ​​the freeze-dried layer can be calculated:

A(area, m2)=V(volume, m)/H(height, m)=0.0018m/0.01m=0.18m2

It is necessary to select a freeze dryer with a load area of ​​0.18 square meters.

2. Cold trap temperature

The cold trap is a device that captures moisture during the freeze-drying process. In theory, the lower the temperature of the cold trap, the stronger the water trapping capacity of the cold trap. However, the lower the temperature of the cold trap, the higher the requirement for refrigeration, the higher the machine cost and the operating cost. The cold trap temperature of the experimental series freeze dryer mainly has several grades such as -45℃, -60℃, and -80℃. Freeze-drying with a cold trap temperature of -45°C is suitable for some products that are easy to freeze-dry, a freeze-drying machine with a cold trap temperature of -60°C is suitable for most products, and a freeze-drying machine with a cold trap temperature of -80°C Suitable for freeze-drying of some special products. The effect of cold trap temperature on water trapping capacity experiments showed that the cold trap temperature dropped from -35℃ to -55℃, and the water trapping capacity improved significantly. The cold trap temperature was lower than -55℃, and the water trapping capacity of the cold trap was not significantly improved. Therefore, in the absence of special requirements, it is an ideal choice to choose a cold trap temperature of about -60°C.

3. Cooling rate

The cooling rate reflects the cooling capacity of the refrigeration system. Under no-load conditions, the temperature of the cold trap should reach the minimum temperature specified by the index within 1 hour. For example, for a freeze-drying machine with a cold trap temperature ≤ -60°C, the machine starts timing from turning on the refrigeration, and the time for the cold trap temperature to reach -60°C should not exceed 1 hour.

4. Ultimate vacuum

The ultimate vacuum degree reflects the leakage of the freeze dryer and the pumping efficiency of the vacuum pump. The vacuum degree of the freeze-drying box, the past view is that the higher the vacuum degree, the better, the industry view that the vacuum degree should be within a reasonable range. The vacuum degree is too high, which is not conducive to heat transfer, and the drying speed decreases. However, the no-load ultimate vacuum degree of the freeze-drying box should reach 15Pa or more.

5. Vacuum time

The emptying speed of the lyophilized box should be pumped from atmospheric pressure to 15Pa within half an hour.

6. Temperature uniformity and flatness of the board

The uniformity and flatness of the slab temperature have a great influence on the uniformity of product quality. The better the temperature uniformity and flatness, the better the uniformity of freeze-dried product quality. The freeze dryer shelf temperature control has a heater type and an intermediate fluid type. The freeze dryer shelf adopts the intermediate fluid control layer with good temperature uniformity and flatness. The layer of the freeze dryer has a hollow sandwich structure. Both cooling and heating are realized by circulating the intermediate fluid in the fluid channel inside the plate layer, so the plate layer temperature is uniform. The shelf temperature control of the bell-type freeze dryer basically uses heaters, and the temperature consistency of the plate layer is slightly poor. But in general, the temperature difference between the layers of the medical freeze dryer should be controlled at ±1.5°C, and the temperature difference within the plate should be ±1°C. The food freeze dryer can be appropriately relaxed.

7. Control system

The control system of the freeze dryer has different types and functions. For the experimental series of freeze dryers, it is mainly used for material freeze-drying process exploration and a small amount of trial production. Therefore, the control system should be able to display the freeze-drying process parameters in real time and automatically record; set, modify and effectively execute the freeze-drying process procedures; have a communication interface to facilitate data collection and storage.