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General Purpose Freeze Dryer have a wide range of applications in the fields of bioengineering, pharmaceutical industry, food industry, materials science and deep processing of agricultural and sideline products. The universal freeze dryer is suitable for drying high-grade raw materials, Chinese herbal medicines, biological, wild vegetables, dehydrated vegetables, food, fruits, chemicals, pharmaceutical intermediates and other materials.
After opening the universal freeze dryer, the material is put into the material box for freezing. The freezing process of the material. On the one hand, the vacuum system performs vacuuming to take away part of the water; on the other hand, the material is contained in certain molecules when it is frozen. The water is discharged to the surface of the material to freeze. After the freezing requirement is reached, the material is heated and dried by the heating system, and the water contained in the material is brought to the freezing and collecting box to be frozen by vacuuming to achieve the requirement of freezing and drying of the material.
The pre-cooler is a cold recovery device for the refrigeration system in the general freeze dryer, and also functions as a low-temperature air regenerator after dehydration. It is a major component of a universal freeze dryer and is a characteristic condition that distinguishes a general freeze dryer from other refrigeration equipment.
In the pre-cooler, the same amount of cold and hot fluid (compressed air) is exchanged by the temperature difference of little difference, for two purposes:
1. Initially reduce the temperature and water content of the moist heat saturated intake air, to a certain extent, reduce the heat load of the evaporator, thereby reducing the energy consumption of the whole machine;
2. The temperature of the compressed air which is lower in temperature and saturated with moisture is recovered, thereby reducing the relative humidity when the compressed air is discharged, so that the gas pipeline does not rust due to the excessive relative humidity of the gas, and also The phenomenon of “hanging” outside the pipe due to the low temperature of the outer wall of the gas pipeline is avoided, and the workshop environment is improved.
The condensed water is attached to the outer wall of the heat exchange pipe to be discharged more easily. Therefore, the saturated compressed air with a higher temperature is usually arranged to go to the shell side of the precooler, and the dry cold air with a lower temperature is taken to the precooler tube.
General Purpose Freeze Dryerhave the following advantages in the food and pharmaceutical industries:
1. During the freeze-drying process, the growth of microorganisms and the action of enzymes cannot be carried out, so that the original sex can be maintained. Since the drying is carried out in a frozen state, the volume is almost constant, the original structure is maintained, and concentration does not occur.
2. Since drying is carried out under vacuum, there is very little oxygen, so some easily oxidizable substances are protected.
3. Drying can exclude more than 95-99% of water, so that the dried product can be preserved for a long time without deterioration.
4. The dried material is porous and spongy. After adding water, it dissolves quickly and completely, and immediately restores the original trait.
5. Freeze-drying is carried out at low temperatures and is therefore particularly suitable for many heat sensitive materials. Such as protein, microorganisms and the like will not degenerate or lose biological vitality. Therefore, it is widely used in medicine.
6. When drying at low temperature, some volatile components in the material are lost little, suitable for some chemical products, medicines and foods to be dry.
The presence of the pre-cooler allows the compressed air to flow through the passage into the system in a universal freeze dryer. The air system and the refrigerant system cross each other in the evaporator, so that the saturated compressed air entering the universal freeze dryer is subjected to two cooling and one temperature rising process, and the absolute water content (dew point) and relative humidity (%) are obtained at the exhaust port. ) Very low dry compressed air.
If the pre-cooler or pre-cooler is not designed properly, the general-purpose freeze dryer will only output humid cold air with low dew point and high relative humidity. Its function has no great application value in industry.
