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Since 1998, the market situation of the vacuum freeze-drying equipment industry has been getting better, and the sales momentum has started to pick up and is in a better state. The large-scale vacuum freeze-drying equipment used in China's Food, health care products and pharmaceutical industry is mainly imported from abroad, and the price is very high. Although there are a few companies in the country that produce such equipment, due to problems in technology, technology, and quality, it is difficult to promote such domestically produced equipment. These problems mainly include: First, uneven heating; Second, insufficient vacuum, affecting drying speed. According to the determination, the critical point of vacuum degree of sublimation drying is the pressure of 4.7 mmHg and the temperature of 0°C.
Microwave vacuum freeze-drying equipment has been available in China for more than 10 years, but it is mostly small equipment. Since the technology for producing this kind of equipment is very difficult, this kind of equipment has not been well promoted.
In the production of microwave vacuum freeze-drying equipment, the most prominent technical problem is the discharge of low-pressure gas: When the gas under vacuum is diluted to a certain degree, it will generate high frequencies when external energy is added. Discharge phenomenon. Low-pressure gas appears high-frequency discharge phenomenon, and the harm is caused by the fact that the microwave energy cannot be transmitted into the material, the microwave reflection is serious, the microwave sealing window is destroyed, and then the vacuum state in the microwave oven is destroyed.
As early as the 1960s, China had developed vacuum freeze-drying equipment, which was mainly used in the pharmaceutical industry. In order to broaden the scope of application, China has also developed a large-scale vacuum freeze-drying equipment, which is planned to be used in the fields of health products and agricultural products processing. However, due to the lack of demand in the domestic market at the time, the vacuum freeze-drying equipment industry was at a low ebb in the late 1960s and early 1980s.