The solids mass flow rate in dilute phase pneumatic conveying lines can be measured in-line using measurements of axially propagated acoustic signals. The system described here uses the difference in upstream and downstream propagation velocities to determine the gas phase velocity, and acoustic attenuation measurements to determine the solids concnetratoin. The solids mass flow rate can be calculated from the concentration and the gas velocity if an estimate is made of the solids slip velocity. In this work, the errors resulting from an incorrect estimate of the solids slip velocity are investigated and it is shown that the mass flow rate calculation does not depend strongly on the slip velocity used if the system is calibrated against a known mass flow rate or total mass flow of solids. Other advantages and disadvantages of this measurement system are also described.
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