For the problem of the use of the frozen hot air circulation oven in many industries, it can be said that the food industry uses more hot air circulation ovens. As long as it is an electronic production industry, it is necessary to use a hot air circulation oven. Automatically used pneumatic machines are used. The main support is to look at the size of the air pump and the amount of gas used. The air removal humidity requirement size determines how to support the hot air circulation oven. If the fine air instrument is equipped with a hot air circulation oven, the number of P is large. The chilled hot air circulation oven can be used in the food industry, such as the dehydrated hot air circulation hot air circulation oven ring oven for vegetable dehydration, the pharmaceutical industry, the lyophilization test for laboratory samples, and the like. As for the hot air circulation oven, it is similar to the ordinary hot air circulation oven. The pulverizer, the mixer and the hot blast stove are indispensable, because the material hot air circulation oven needs to be pulverized and mixed before the chilled hot air circulation oven, and the hot air circulation oven The machine itself needs a heat source. Of course, there is also a medical frozen hot air circulation oven, and its properties are matched with the medical frozen hot air circulation oven. Introduction of the principle of the frozen hot air circulation oven First, the definition and advantages of vacuum freezing hot air circulation oven: The product is completely frozen, and the ice crystals are sublimated under a certain vacuum condition, thereby achieving the purpose of low-temperature dehydration. This process is called Freeze-drying, referred to as freeze-drying. The lyophilized solid material exhibits a porous structure due to the sublimation of tiny ice crystals, and maintains the volume of the original frozen hot air circulating oven junction. It is easily dissolved and restored after adding water, and the temperature of the product is kept at a lower temperature during the sublimation process. (generally lower than -250C), and therefore hot air circulation ovens such as enzymes, hormones, nucleic acids, blood and immunological products are particularly suitable for those which are not heat resistant. The result of the hot air circulation oven can discharge more than 95~99% of water, which is beneficial to the preservation of the product during the long hot air circulation oven period. The hot air circulation oven process of the product is carried out under vacuum conditions, so it is not easy to oxidize. Lyophilization has been proved to be a very effective means for the chemical, physical and biological instability of some biochemical drugs in hot air circulation ovens. With the rapid development of biochemical drugs and biological agents in DMH drying ovens, freeze-drying technology will increasingly show its importance and superiority. Second, the structure and function of the medical frozen hot air circulation oven machine: The medical frozen hot air circulation oven is composed of a refrigeration system, a vacuum system, a heating system, and an electrical instrument control system. The main components are hot air circulation oven, condenser, chilled hot air circulation oven unit, vacuum pump heating/cooling unit, etc. The lyophilization of the product is carried out in a hot air circulation oven, and the shelf in the hot air circulation oven is made of stainless steel plate, and a medium conduit is distributed therein to cool or heat the product, and a vacuum is arranged behind the hot air circulation oven. The sensor converts the degree of vacuum into a signal. The door is inlaid with a sealing rubber ring. It can be coated with vacuum grease before use to ensure the sealing of the box. Preferably, the condenser is wrapped around a hot air circulating oven, and the stainless steel cylinder is surrounded by a plurality of sets of hot air circulating oven cold air coils, and the working temperature is lower than the temperature of the products in the hot air circulating oven, and the lowest is -5 hot air circulation. In the oven 50C, the water vapor sublimated from the product can be sufficiently condensed on the inner surface of the stainless steel cylinder surface in contact with the cold coil, thereby ensuring the smooth progress of the freeze-drying process, and the smooth CHG series flow-through oven cylinder The biggest advantage of the structure is that it is easy to clean, and after the lyophilization is finished, the frost layer can be removed by electric heating. The rotary vane vacuum pump is used to evacuate the system. An electromagnetic vacuum valve with automatic deflation is installed at the inlet of the hot air circulating oven mechanical pump. It is controlled by the same power source as the rotary vane pump. When the pump is stopped, the electromagnetic valve is used. Automatic shut-off and deflation into the vacuum pump both protects the vacuum system and prevents the vacuum pump from returning oil to the system. In the refrigeration system, two 2.2Kw semi-closed freezers are used in parallel, and the high-pressure refrigerant liquid (fluorine-free refrigerant V55C) from the wind-hot air circulation oven condenser passes through the hot air circulation oven filter and the electromagnetic valve to the capillary. After the throttling enters the evaporator, the pressure in the evaporator is lowered due to the suction effect of the hot air circulation oven of the freezer, and the liquid hot air circulating oven refrigerant absorbs the heat of the environment and rapidly evaporates in the hot air circulation oven. The low-pressure refrigerant gas is drawn back by freezing, and then compressed into a high-pressure gas to complete a refrigeration cycle. The cold-discharge pipe in the heating/cooling device is cooled by the cold-discharge pipe in the condenser and the cold-air coil in the condenser. In the middle of evaporation, they supply refrigerant through two different solenoid valves. The heating system consists of an electric heating tube, a medium (silicone oil), a media pump, a media box, and the like, and a circulating pipeline is formed. After the silicone oil is heated by the electric heating tube, the medium pump is transported to the media duct of the hot air circulation oven in the dry box shelf to carry out the product. Heating, providing sublimation heat, when frozen, the silicone oil is cooled by the cooling pipe, and is transported by the media pump to the media duct of the hot air circulating oven shelf center in the hot air circulating oven to cool and freeze the product. The electrical instrument control hot air circulation oven system is designed for mechatronics. It is controlled by a special industrial control motor. All shelf temperature, media temperature and product temperature can be displayed on the centralized display. For specific adjustment control, please refer to the system manual. Third, the basic principles and practice of freeze-drying The quality requirements for freeze-dried products are: constant biological activity, uniform appearance and color, full shape, firm structure, fast dissolution rate and low residual moisture. To obtain high quality products, a comprehensive understanding of the theory and process of lyophilization should be obtained. The lyophilization process includes three stages of pre-freezing, sublimation and re-drying. Reasonable surface effectively shortening the freeze-drying cycle has obvious economic value in industrial production.