Abstract：In view of the high requirement of solid phase quantification for pneumatic conveying in some parts of industrial& agricultural production, a common positive pressure Laval nozzle bin pneumatic conveying system and back feed automatic control system were established. Experiments were carried out in this pneumatic conveying system by transporting bechilite powder.The trend of solid conveying capacity during the conveying process is obtained according to the results of precise weighing sensor test and ultrasonic testing method. Through the comparison of solid flow before and after automatic control, it can be seen that the stable conveying time increases 16¹8 s, meanwhile the fluctuation of solid conveying capacity is less than ±8% in condition of automatic control status. The results show that the automatic control scheme improves the stability of solid flow greatly.

Keywords: positive pressure Laval nozzle bin; pneumatic conveying; solid conveying capacity