Assembly-line Microwave Dryer

Ju Yong Chol, a section head at the Nano Physics Engineering Institute, and his research team members built an assembly-line microwave dryer for drying pills at pharmaceutical plants.

Microwave heating, compared to other ways of heating, is exellent in thermal efficiency and heating rate since it is focused on target objects only. It provides uniform thermal spread on the outside and inside of objects. Easy adjustment of microwave output leads to easy adjustment of heating rate. The dryer is simple in its structure and easy to operate. Microwave drying is being widely introduced in several fields like pharmaceutical industry and foodstuff industry thanks to its high production efficiency and high quality of products.

The assembly-line microwave dryer consists of a microwave generation sector, a control sector, a conveyor sector, a ventilation sector, a microwave leak checking sector, etc.

In the microwave generation sector are six magnetrons with 700W output. 2.8kW microwave is generated in real time by four of them in operation in turns and two cooling down.

In the control sector, there are electric circuit blocks to turn 4 magnetrons on and 2 magnetrons off. It controls the transmission speed of the conveyor.

In the conveyor sector, the belt on the bottom of the drying cavity is moved by the reduction motor with 90W output and 1 450r/min. The transmission velocity is 0~70cm/min.

In the ventilation sector, a 300L/min exhauster between the two drying cavities expels wet steam from the drying cavity generated during drying processes at the deflation speed of 3m/s.

In the microwave leak checking sector, the reflection-type microwave leak checker reflects the microwave propagated through the inlet and outlet of the drying cavity back into the drying cavity, which checks microwave leak and meets the permitted limit on the international standard.

The dryer proved to be effective in reducing the humidity of pills by 5% at 40kg per hour. Hygienic safety of products is ensured and production cost is reduced to half.