(11c) Effect of Flow Aids on Calcium Carbonate Flow Rate in the Dilute Phase Pneumatic Conveying System

Calcium Carbonate (CaCO3) is one of the difficult materials to convey in bulk solids handling system. Based on the angle of internal friction, angle wall friction, and flow function, CaCO3 needs steeper hopper angle and wider outlet dimension for mass flow, which may not be possible in many situation due to headroom requirement. In that situation, it is common to use flow aids such as fluidizer, impactors, vibrators and moving bottom. In this study, effectiveness of these flow aids fluidizer and impactors were analyzed. The vacuum dilute phase pneumatic conveying experimental set-up for the study was selected with 125 feet horizontal and 25 feet vertical line in a 4” sch 10 carbon steel pipe. Three target flow rate of 3000, 6000 and 9000 lb/h and three target pick-up velocities of 5250, 5750 and 6250 FPM were selected. The following flow aids fluidizer, and impactors were selected. The pressure drop of negative (vacuum) pressure of 5-7 inches of Hg were observed. Different combination of impactors (pulses/min) with and without fluidizer were studied and analyzed.