Influence of the design parameters of the intake of a pneumatic conveyor of an aerodynamic heating dryer on its efficiency

Drying shaft of the modular dryer of aerodynamic heating is equipped with an outlet in the form of a combination of a non-driven mechanical outlet and a pneumatic conveyor. It is established that the design of its intake has a great impact on the performance of the pneumatic conveyor. The research purpose was to assess the influence of design parameters of the intake of a pneumatic conveyor on its performance. When studying the transportation of wheat grain, the authors tested five design options of the intake for a material pipeline of a 120 × 60 mm rectangular cross-section and a material pipeline of a 110 mm circular cross-section. It was found that the maximum capacity of 422.3 kg/h and mass concentration of the mixture 0.9 kg/kg are provided by the rectangular cross-section material pipeline with a protective insert. The direct discharge and the rectangular cross-section of the 120 × 60 mm material pipeline with a passive vibrator ensure the maximum capacity of 416.4 kg/h and a mass concentration of the mixture of 0.7 kg/kg. When using the outlet with a length of 3 cm instead of 6 cm, one can obtain a capacity of 466.8 kg/h and a mass concentration of the mixture of 0.89 kg/kg. To ensure stable operation and a capacity up to 450 kg/h, the intake of the pneumatic conveyor of the experimental modular dryer of aerodynamic heating should be equipped with a direct outlet of a 60 × 60 mm cross-section with a length of not more than 3 cm, connecting the dryer outlet with the intake of the material pipeline of a rectangular 120 × 60 mm cross-section, equipped with a passive vibrator. The air flow velocity at the intake of the pneumatic conveyor should be within 15.7 to 17.0 m/s. The use of a protective insert in the outlet is a promising way to increase the capacity of the pneumatic conveyor under the condition of increasing the initial air flow velocity at its intake.