PARTICLE VELOCITY MEASUREMENTS THROUGH ELECTROSTATIC FIELD FLUCTUATIONS USING EXTERNAL PROBES

ABSTRACT

Two new probes for measuring particle velocity and flowrate based on the elctrostatic field nature of a pneumatic transport system are Introduced. The first probe is based on the current of charged particles inducing a current in a coil placed perpendicular to the flow. The magnitude of the current induced appears to be related to the amount of charged particles passing through the coil and the velocity of the particles. The second probe utilizes fluctuations in the electrostatic field which are picked up by two probes placed a fixed distance along the axis of the flow. The signals from these two probes are identical in waveform but of set in time; therefore, the particle velocity can be obtained by cross-correlation techniques. Both probes are non-intrusive and realtively inexpensive.     

PREDICTION OF PRESSURE DROP IN PNEUMATIC TRANSPORT SYSTEMS AT VARIOUS PIPE ORIENTATIONS USING AN EMPIRICAL CORRELATION FOR THE PARTICLE VELOCITY

ABSTRACT

A new empirical correlation for the particle velocity which incorporates the angle of inclination is proposed here. This correlation coupled with the expression for the solids friction factor obtained from the force balance on the particle was used to predict the pressure drops in the 0.0266 m and 0.0504 m systems held at various angles of inclination. Particles used in these systems included glass particles of 67, 450, and 900 µm weight mean diameter. The existence of minimum points in the predicted pressure drop curves as a function of gas velocity was corroborated by these two expressions.