Microwave vacuum drying technology
Late eighties began the development of the domestic microwave vacuum drying equipment, through years of efforts, to the year 2000 , the successful solution of the low-pressure arc discharge microwave field , laying the heating temperature difference between the material layer , non-contact temperature measurement inside the microwave , etc. number of problems, from the experimental stage into the industrial production stage. Of food engineering , pharmaceutical engineering, biological engineering, chemical engineering, materials engineering, and deep processing of agricultural and sideline products provides a new and efficient drying equipment.
Microwave vacuum drying characteristics:
Efficient: conventional vacuum drying equipment , ( assuming a vacuum pressure of 7.37kpa, material dehydration temperature was 40 ℃, 1kg heat of water vapor is 574 kcal ) , due to the vacuum case, the heat transfer by convection is very difficult, only conduction for the heating rate is slow, long drying cycle , energy consumption . Microwave vacuum drying equipment is used in radiation energy transfer , is the whole medium heat , no other heat transfer media , to avoid the above drawbacks , so fast, high efficiency, greatly shorten the drying cycle , reduce energy consumption . Compared with conventional drying techniques can improve work efficiency more than four times .
Uniform heating : Since microwave heating is the material inside and outside simultaneously heated , the material inside and outside temperature difference is small , does not produce conventional heating heating appears inconsistent condition inside and outside , leaving the drying quality greatly improved. Easy to control : easy and automated continuous production , because the microwave power can be adjusted quickly and without inertia characteristics, easy to timely control , easy to adjust and determine the process parameters .
Devices are small, easy installation and maintenance :
Products of good quality : Compared with the conventional method , the processing of the product quality has improved greatly .
Furthermore microwave equipment with disinfection , sterilization efficacy , product safety and hygiene. Extended shelf life .
From the above described features , the energy conservation, energy , improve product quality , health and safety aspects of equipment investment and low cost can be seen its remarkable economic and social benefits . In the dehydrated vegetable processing , a variety of drying equipment, process performance, economic efficiency, product quality comparison results are shown in Table .