Design and Application of Low Velocity Pneumatic Cut Stem Drier

The existing pneumatic driers in tobacco industry generally associate with some shortcomings, such as long drying path, high air velocity and higher tobacco degradation, a low velocity pneumatic cut stem drier was designed, its core part was an inverted cone-shaped drier. The feeding duct was divided into two layers to prevent stem from depositing. An air spreading device, a stem spreader and a foreign matter rejector were arranged at the bottom of drying duct to improve heat exchanging efficiency. The air velocity at the upper part of drying duct was set at about 3 m/s. The internal structure and inner wall surface of drying duct were specially treated and the flow parameters were optimized to reduce system's loss. The results of application showed that the drier had the merits of low hot air velocity and uniform material heating. The uniformity of moisture content in output cut stem was effectively improved, the breakage of cut stem was reduced, the proportion of long strands increased by about 5 percentage points, while that of short strands decreased by about 1 percentage point and the extreme difference of moisture content in output cut stem decreased by 1.5 percentage points.