I. Overview Microwave vacuum drying equipment is a new type of microwave energy application equipment combining microwave energy technology and vacuum technology. It has a series of advantages of microwave and vacuum drying, and overcomes the shortcomings of conventional vacuum drying cycle and low efficiency. In the drying process, the work efficiency can be improved by 4 to 10 times compared with the conventional method. With high drying yield, good quality and low processing cost, microwave vacuum drying equipment is a high-tech product integrating electronics, vacuum, mechanics, thermodynamics, program control and other disciplines. Based on the in-depth study of physical changes in matter, internal and external heat and mass exchange, and water migration under vacuum conditions, a new technology and process have been developed. In industrial large-scale production, there are many items that cannot be dried under high temperature conditions, such as some medicines, chemicals, nutritious foods, and high-grade Chinese herbal medicines such as ginseng and antler. In order to ensure product quality, the drying treatment must be below 100. °C or at room temperature, it is known that the gas pressure is lowered and the boiling point of water is also lowered. For example, at one atmosphere (101.3 kPa), the boiling point of water is 100 ° C, and at 0.073 atmosphere (7.37 kPa), the boiling point of water is 40 ° C. Under vacuum conditions, heating the object allows the internal moisture of the object to evaporate without warming up. Air convection heat transfer is difficult due to vacuum conditions, and heat is supplied to the material only by means of heat conduction. The conventional vacuum drying method has a slow heat transfer rate, low efficiency, and difficulty in temperature control. Microwave heating is a kind of radiant heating. It is a direct action of microwave and material to heat it inside and outside. It does not need to transfer heat through convection or conduction. Therefore, the heating speed is fast, the drying efficiency is high, and the temperature control is easy. In developed countries, developed countries began to develop industrial microwave vacuum drying equipment in the 1980s, and achieved good results in practical applications. French International Microwave Company processed the seedless raisins with microwave vacuum drying equipment, and changed the traditional process to 65 ° C, 24 hours hot air drying to 50 ° C, 5 hours microwave vacuum drying, product quality and output were greatly improved. In the late 1990s, our company took the lead in researching and developing microwave vacuum equipment in China. Through several years of efforts, we completed the development of industrialized 10KW microwave vacuum drying equipment in 2000. It provides a new and efficient drying equipment for pharmaceutical engineering, bioengineering, chemical engineering, materials engineering and deep processing of agricultural and sideline products. Second, the advantages of microwave vacuum drying equipment 1, efficient Conventional vacuum drying equipment uses steam for heating. It needs to be heated from the inside to the outside. The heating speed is slow and it takes a lot of coal. The microwave vacuum drying equipment uses electromagnetic wave heating, without heat transfer medium, and directly heats the inside of the object. The heating rate is fast, and the 1 kW microwave energy can heat the water at normal temperature to 100 ° C in 3-5 minutes, thereby avoiding the above disadvantages, so the speed is fast, the efficiency is high, the drying cycle is greatly shortened, and the energy consumption is reduced. Compared with conventional drying technology, it can improve work efficiency by more than four times. 2, heating evenly Due to the microwave heating, the materials are heated simultaneously from the inside to the outside, the temperature difference between the inside and the outside of the material is small, and the internal and external heating inconsistent in the conventional heating does not occur, thereby causing the expansion effect, which is favorable for the pulverization and greatly improves the drying quality. . 3, easy to control, easy to continuous production and automation, due to the rapid adjustment of microwave power and inertia, easy to control, you can adjust the temperature between 40 °C -100 °C. 4, small size, easy installation and maintenance 5, the product quality is good, compared with the conventional method, the quality of the processed product has been greatly improved. 6, microwave has the effect of disinfection, sterilization, product safety and hygiene. The shelf life is long. 7. The economic benefits are significant. From the above-mentioned characteristics, energy saving, consumption reduction, product quality improvement, safety and hygiene, and low equipment investment cost can be seen to show significant economic and social benefits. Third, the example Project dynamic microwave drying spray drying steam vacuum drying Drying time 45~70 minutes 3~5 seconds 20~45 hours Drying temperature 45~60 degrees (arbitrary setting) inlet air 180 degrees 50~60 degrees (difficult to control) Extract loss 02~5%3% Moisture 4~5%2~4%4~6% The content loss is 20~30% lower than other equipment, 20~30% drop 20~30% The production needs the same condition, one needs 3 sets, 5 sets are needed. The cost per kilogram of dry paste is 0.4~0.5 yuan/kg3~4 yuan/kg3~4 yuan/kg Drying method: process configuration The above can be seen: the drying cost is low, the benefit is good, the equipment is small, which is equivalent to 20% of the area of ​​the steam vacuum dryer and 30% of the spray drying equipment, which greatly saves the purification plant. Dynamic vacuum microwave dryer is not only used for traditional Chinese medicine extracts, but also for food products, food chemicals, especially for pastes and viscous materials. It is also more suitable for killing bacteria. Fourth, the conclusion The successful development of this product has made breakthroughs in many key technologies. It also proposed some theoretical basis and methods of design, and gained a lot of valuable experience in practice, which laid a solid foundation for the further development of this technology. The actual operation shows that the equipment has excellent performance, advanced technology and reasonable design. It is a new technology and new product with remarkable economic benefits, good social benefits and high promotion value. Dongguan Anmeixuan Electronic Technology Co., Ltd , https://www.hyashine.com
The process performance, economic benefits and product quality of a variety of drying equipment processed by a pharmaceutical factory in Jiangxi were compared. The drying indexes are as follows: