The working principle of the freeze dryer is to freeze the dried item below the triple point temperature, and then directly sublime the solid water (ice) in the item into water vapor under vacuum conditions, take it out of the item and dry it.
After pretreatment, the material enters the quick-freezing warehouse for freezing, then enters the drying warehouse for sublimation and dehydration, and is packaged in the post-processing workshop.
The vacuum system establishes low pressure conditions for the sublimation drying chamber, the heating system provides the latent heat of sublimation for the material, and the refrigeration system provides the required cooling capacity for the cold trap and the drying chamber.
The equipment adopts university radiation heating to make the material heated evenly; adopts university steam trap to achieve rapid defrosting; adopts university vacuum unit to achieve oil-water separation.
Freeze-drying technology is a new type of food processing technology, which is very healthy and does not harm the human body. Let's take a look at how it is different from ordinary drying:
Ordinary drying is one of the ways to keep substances from deteriorating. There are many drying methods, such as sun drying, boil drying, drying, spray drying and vacuum drying. However, these drying methods are all carried out at temperatures above 0°C or higher.
The product obtained by drying is generally reduced in volume and hardened in texture. Some substances are oxidized, and most of the volatile components will be lost. Microorganisms will lose their biological activity, and the dried substances will not easily dissolve in water.
The principle of freeze-drying is well understood. First, put fresh fruits and vegetables in a freeze-drying machine at about minus 50°C for freezing. After the fruits and vegetables are frozen, vacuum the drying box. After the vacuum is formed, increase the temperature slightly.
The ice in the fruits and vegetables sublimates directly into water vapor and leaves the fruits and vegetables, while the remaining fruits and vegetables "skeleton" remain unchanged in volume and loose and porous. The moisture that can be removed by freeze-drying can reach more than 95%.
Freeze-drying technology is carried out at low temperature, such as proteins and microorganisms, without denaturation or loss of biological activity. When drying at low temperature, the loss of some volatile components in the substance is very small, which is suitable for drying some chemical products, medicines and food.
During the freeze-drying process, the growth of microorganisms and the action of enzymes cannot proceed, so the original properties can be maintained. Since it is dried in a frozen state, the volume is almost unchanged, the original structure is maintained, and no concentration phenomenon occurs.
Since drying takes place under vacuum with very little oxygen, some oxidizable substances are protected. Drying can remove more than 95-99% of the water, so that the dried product can be stored for a long time without deterioration.
It is very common in daily life. Air freeze drying technology, referred to as freeze drying, is also known as sublimation air drying. Freeze-drying is a specific method of pre-freezing water-containing materials and then subliming them in a vacuum state to obtain air-dried objects. The original biological and chemical properties of the freeze-dried objects are basically unchanged, and they are easy to store for a long time. After being soaked in water, they can be restored to the form before freeze-drying, and their original biochemical properties can be maintained.
Therefore, freeze-drying technology is widely used in various fields such as industrial chemistry and medical equipment. However, many people are not very clear about how to use it specifically, and they are not very aware of the precautions. Next, let us understand the freeze dryer. First of all, let's take a look at how to operate it and get ready to work:
Before using the freeze dryer, place the objects to be air-dried in a low-temperature refrigerator or liquid nitrogen, so that the objects are completely frozen and solid, and then freeze-drying can be performed. The main engine and the vacuum pump are connected with each other by a vacuum tube, and international standard clamps are used at the connection. The clamp contains a sealing rubber ring.
Before connecting, apply an appropriate amount of vacuum grease on the rubber ring, and then clamp it with the clamp. There is a power socket for the vacuum pump on the right side panel of the main unit, and the power cord of the vacuum pump is connected well.
Check the vacuum pump to confirm that the vacuum pump oil has been filled, and it cannot be run without oil. The oil level should not be less than the center line of the oil mirror.
The "o" type sealing rubber ring above the cold trap of the main unit should be kept clean. When in use, a thin layer of vacuum grease can be applied, the plexiglass cover is placed on the rubber ring, and it is gently rotated a few times to facilitate sealing.
Application of Freeze Dryer Machine
Freeze dryers are widely used in medical, pharmaceutical, biological research, chemical, food and other fields. Freeze-dried items are easy to store for a long time. After adding water, they can be restored to the state before freeze-drying and maintain their original biochemical properties.
LD series electric heating series freeze dryer can speed up drying efficiency and save energy. It offers a variety of freeze-drying program settings. Through programming, heating will curve with temperature and time. Suitable for scientific research experiments or small batch production.
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