Application of microwave low temperature vacuum drying equipment

1、 Microwave vacuum drying equipment is a new type of microwave energy application equipment which combines microwave energy technology and vacuum technology It combines a series of advantages of microwave and vacuum drying, and overcomes the disadvantages of long cycle and low efficiency of conventional vacuum drying In the process of general material drying, the work efficiency can be increased by 4-10 times than that of conventional methods Microwave vacuum drying equipment is a high-tech product integrating electronics, vacuum science, mechanics, thermodynamics, program control and other disciplines It is developed on the basis of in-depth research on physical changes of materials, internal and external heat and mass exchange and water transfer under vacuum conditions A new technology and process In large-scale industrial production, there are many items that can not be dried under high temperature, such as some drugs, chemicals, nutritious food, ginseng, antler and other Chinese herbal medicines In order to ensure the quality of products, the drying treatment must be carried out under the condition of less than 100 ℃ or room temperature As we all know, the air pressure is reduced, and the boiling point of water is also reduced, such as at a atmospheric pressure (1 The boiling point of water is 100 ℃ at 0.3kpa) and 40 ℃ at 0.073 atmospheric pressure (7.37kpa) Under vacuum condition, the water inside the object can be evaporated without heating Because it is difficult to carry out convective heat transfer in vacuum, only heat conduction can provide heat for materials The conventional vacuum drying method is slow in heat transfer, low in efficiency and difficult in temperature control Microwave heating is a kind of radiation heating, which is a direct interaction between microwave and materials, so that they are heated inside and outside at the same time, without convection or conduction to transfer heat, so the heating speed is fast, the drying efficiency is high, and the temperature control is easy In the 1980s, developed countries began to develop industrial microwave vacuum drying equipment, and achieved good results in practical application French international microwave company uses microwave vacuum drying equipment to process seedless raisins It changes the traditional technology from 65 ℃ and 24-hour hot air drying to 50 ℃ and 5-hour microwave vacuum drying The product quality and output are greatly improved In the late 1990s, our company began to develop microwave vacuum equipment in China Through several years' efforts, we completed the development of industrial 10kW microwave vacuum drying equipment in 2000 It provides a new type of drying equipment for pharmaceutical engineering, biological engineering, chemical engineering, material engineering and deep processing of agricultural and sideline products Advantages of microwave vacuum drying equipment 1 The conventional vacuum drying equipment uses steam for heating, which needs to be heated from inside to outside The slow heating speed needs to consume a lot of coal, while the microwave vacuum drying equipment uses electromagnetic wave heating, which does not need heat transfer medium, and directly heats to the inside of the object The heating speed is fast The 1kW microwave can heat the water under normal temperature to 100 ℃ in 3-5 minutes, avoiding the above disadvantages Therefore, the speed is fast, the efficiency is high, the drying cycle is greatly shortened, and the energy consumption is reduced Compared with the conventional drying technology, the working efficiency can be increased more than four times 2 Uniform heating: due to microwave heating, materials are heated from inside to outside at the same time The temperature difference between the inside and outside of materials is very small, which will not cause the inconsistent situation of the internal and external heating in the conventional heating, resulting in the expansion effect, which is conducive to crushing and greatly improving the drying quality 3 It is easy to control, convenient for continuous production and automation Due to the fast adjustment of microwave power and no inertia, it is easy to control in real time, and the temperature can be adjusted arbitrarily between 40 ℃ - 100 ℃ 4 The preparation volume is small, the installation and maintenance are convenient 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 efficacy of disinfection and sterilization, and the product is safe and sanitary Long shelf life 7 Remarkable economic benefits From the above-mentioned features, we can see that its economic and social benefits are significant in energy conservation, consumption reduction, product quality improvement, safety and health, and low investment cost of equipment Three, an example of a pharmaceutical factory in Jiangxi processing various drying equipment processing performance, economic efficiency, product quality and so on, the drying index comparison is as follows: Project Dynamic microwave drying, spray drying, steam vacuum drying and drying time 45~70 minutes 3~5 seconds 20 ~45 hours Drying temperature 45-60 degrees (arbitrary setting), air inlet 180 degrees 50-60 degrees (difficult to control), extract loss of more than 02-5% 3%, moisture 4-5% 2-4% 4-6% content loss increased by 20-30% compared with other equipment, decreased by 20-30%, output decreased by 20-30% Under the same conditions, one needs 3 sets of 5 sets, dry paste cost per kilogram is 0.4-0.5 yuan / kg3-4 yuan / kg3-4 yuan / kg Drying method: the above process configuration can be seen: the drying cost Zui is low, the benefit Zui is good, the equipment occupies a small area, 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 suitable for traditional Chinese medicine extract to face health products, food chemical products, especially paste and high viscosity materials, but also plays a better role in killing bacteria 4 Conclusion: the successful development of this product has made a breakthrough in many key technologies, and has also put forward some theoretical basis and methods for design, and has made many valuable experiences in practice, which has 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.