A study on some effects of a drag-reducing agent on the performance of a stirred vessel

The influence of the addition of a drag reducing agent (100 ppm PAA) to a pure liquid (water) in a stirred vessel has been studied. The vessel was stirred with two types of agitators, a Rushton turbine and an axial A310 impeller. This study was meant to implement previous findings with new data and various types of measurements were performed to determine a number of parameters. It is confirmed that the drag-reducing agent decreases power draw and increases mixing time. Mean flow and the fluctuating velocities were determined (with the PIV technique) and notable reduction in turbulence intensity was detected. The mechanism of tracer dispersion (followed by the PLIF technique) was also documented qualitatively. Finally, the influence of the drag-reducing agent on the particle size distribution of the solid product of a precipitation reaction (reaction of barium chloride and sodium sulphate) was shown. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.