Characteristics of ring probes for measuring pneumatically conveyed solids

Solid particles will be charged when they are pneumatically conveyed in a pipe. The charged particles then cause the generation of electrostatic charges on the surface of a ring probe, which is a section of the transportation pipe and serves as a solid particle flow sensor. A series of experiments were carried out to study the characteristics of the ring probe. The experimental results show that the ring probe features as a low pass filter (LPF) to the particle flow fluctuation, and the cutoff frequency of the LPF increases with the reduction of the slenderness ratio of the ring probe. The paper also discusses about the relationship between the sensitivity and the slenderness ratio of the ring probe. The recommended slenderness ratio of the ring probe ranges from 0.3 to 3.