The late 1980s began to develop microwave vacuum drying equipment, through years of efforts, to 2000 before and after the successful solution to the low-pressure microwave field from the arc discharge, shop between the heating temperature difference, microwave field non-contact temperature measurement A number of problems, from the experimental stage into the industrial production stage. It provides a new and efficient drying equipment for food engineering, pharmaceutical engineering, bioengineering, chemical engineering, material engineering and deep processing of agricultural and sideline products.
Microwave vacuum drying characteristics:
High efficiency: conventional vacuum drying equipment, (assuming a vacuum pressure of 7.37kpa, material dehydration temperature of 40 ℃, 1kg of water vaporization is 574 kcal), because in a vacuum, the heat through the convection is very difficult, can only conduct Carried out, the heating speed is slow, the drying cycle is long and the energy consumption is big. Microwave vacuum drying equipment is used in radiation transmission, the media is the overall heating, no other heat transfer medium, to avoid the above shortcomings, so fast, high efficiency, greatly shorten the drying cycle, lower energy consumption. Compared with conventional drying technology can improve work efficiency more than four times.
Heating evenly: As the microwave heating is the material inside and outside the heating, the material inside and outside the temperature difference is small, does not produce conventional heating inside and outside the heating inconsistency of the situation, leaving the drying quality greatly improved. Easy to control: to facilitate continuous production and automation, due to microwave power can be quickly adjusted and no inertia characteristics, easy to timely control, easy to adjust and determine the process parameters.
Equipment, small size, easy installation and maintenance:
Product quality: Compared with the conventional method, the quality of the processed product has a more substantial increase.
In addition, microwave equipment with disinfection, sterilization effect, product safety and health. Shelf life can be extended.
From the above mentioned characteristics, energy saving, consumption reduction, improve product quality, safety and health, equipment, low investment costs can be seen in all aspects of its economic and social benefits significantly. In the processing of dehydrated vegetables, a variety of drying equipment, process performance, economic efficiency, product quality and other comparative results in the table.
Project
Microwave vacuum equipment freeze drying equipment hot air drying equipment
Finished product quality
Vitamins and other nutrients preservation rate
85% 95% Thermal decomposition, no preservation
The following are the same as the "
Flavor view
Basic save all save large changes
Rehydration
3 minutes to recover 3 minutes to recover more than 15 minutes
Chewing sensation
Good difference
Device characteristics
Equipment cost
Half of the freeze dryer is expensive
Operating costs 
2-3 yuan / kg 20 yuan / kg 1-1.5 yuan / kg
Drying time
3-4 hours 20 hours 5-6 hours
other
Area
small Medium Large
Bactericidal effect
No no no
Comparison of drying efficiency between microwave vacuum equipment and conventional vacuum equipment
Model Power consumption per hour Water efficiency (kg / kw.h)
Microwave vacuum equipment
25kw 10kg 0.4
The following are the same as the "
Vacuum equipment
23kw 2.5kg 0.1
By comparing the efficiency of microwave vacuum drying equipment for conventional vacuum equipment 4 times, we can see microwave vacuum drying is a significant economic benefits, promote the high value of high-tech. At present, our company developed a new type of industrial microwave vacuum drying equipment has been identified by the relevant units of the country, from 2kw-100kw microwave vacuum drying equipment has formed a series of products. Which will be China's national economy and many fields and scientific research departments to provide a modern high-tech drying equipment.
Microwave vacuum drying equipment is a microwave technology and vacuum technology combined with a new type of microwave energy application equipment, which combines microwave and vacuum drying a series of advantages, to overcome the conventional vacuum drying cycle is long, low efficiency in the general material Drying process, with a high yield of dry, good quality, low processing costs, microwave drying equipment, a set of electronics, vacuum, mechanical, thermodynamics, program-controlled and other disciplines as one of the high-tech products, On the basis of the physical changes in the material during the drying process, the internal and external heat and mass exchange and the moisture migration process under vacuum, the development of a new technology and new technology. Microwave vacuum drying equipment consists of microwave generator, vacuum drying chamber, material rotating disk, vacuum system and electronic control system.
In order to ensure the quality of the product, the drying process must be carried out at a temperature of less than 100 ° C or above, in order to ensure the quality of the product. In order to ensure the quality of the product, the dried product must be dried at high temperature, such as some drugs, chemicals, nutritious food and ginseng, velvet and other high-grade Chinese herbal medicine. The boiling point of the water is 100 ° C, and at a temperature of 0.073 (7.37 kPa), the boiling point of the water is 40 ° C, and the boiling point of the water is lower than that at the atmospheric pressure (101.3 kPa). Under vacuum conditions, heating the object can make the water inside the object in the absence of temperature rise in the state of evaporation. As the air convection heat transfer is difficult to carry out, only by means of heat conduction to the material to provide heat. Conventional vacuum drying method is very slow conduction speed, low efficiency, and the temperature control is difficult, the heated material will produce internal and external temperature difference. Microwave heating is a kind of radiant heating, which is a direct effect of microwave and object, so that it is heated at the same time, without passing heat or convection or conduction. Therefore, the heating speed is high, the drying efficiency is high and the drying quality is high.
Developed countries such as the United States, France, Japan in the eighties began to industrial microwave vacuum drying equipment development. And in the practical application of good results. University of California, with a company, with microwave vacuum drying equipment processing seedless raisins, the traditional process 65 ℃, 24 hours hot air drying into 50 ℃, 5 hours microwave vacuum drying, product quality greatly improved. France International Microwave Co., Ltd. microwave vacuum dryer (2450MHz, 48kw) processing instant orange powder, the product not only to maintain the original color, smell and taste, its vitamin retention is much higher than the spray drying.