Measurement of granular flow in a vertical column using pulse induction (PI)

Gravity flow of granular materials in vertical columns can generate pressure and density fluctuations which are difficult to quantify. Examination of prior research led us to propose a new measurement technique based on the principle of pulse induction (PI) for metal detection. An experimental device using 8 mm diameter spherical particles flowing through a polyvinylchloride (PVC) pipe of 75 mm diameter and 1000 mm height was developed to demonstrate the feasibility of PI. Ten PI coils were used to quantify tracer movement through the column with time. Average and instantaneous velocities were determined for five diameters of outlet orifices: 68.0, 62.5, 54.5, 44.0 and 36.5 mm. Flow rate was calculated and modelled. When compared to prior research, PI proved to be a reliable method for flow measurement in opaque ducts.

► The feasibility of using PI for flow measurement in vertical column demonstrated.
► Flow of 8 mm diameter spherical plastic particles through a PVC pipe measured by PI.
► Vertical velocity of particles did not depend on the height of beads but on the size of the orifice.
► It was shown that the granular flow rate can be modelled by the Beverloo et al. (1961) function with n = 2.39.
► PI measurement of the coupled time-height granular flow proved to be reliable.