INFLUENCE OF DRAG REDUCING ADDITIVES ON POWER-CONSUMPTION IN AGITATED VESSELS

Polyethylene Oxide (PEO) was used as a drag reducing additive in an agitated vessel and its effect on the reduction of power consumption of different impellers was investigated. The experiments covered a concentration range of 0 to 6000 ppm of the PEO solution, a Reynolds number range of 4.0 x 104 to 5.0 x106 and a Froude number range of 0.3 to 13.0. The data were correlated and an empirical equation was developed which gave the power number as a function of the Reynolds number, the Froude number, PEO concentration and the geometric factors accounting for the relative sizes of impeller and vessel. The incorporation of the concentration effect in the conventional empirical equation commonly used for agitated vessels makes the developed equation extremely valuable for power consumption prediction under different experimental conditions including polymer concentration in the Newtonian fluid range. A comparison between the experimental data and calculated data using the empirical equation indicated that the agreement was excellent over the range of the parameters studied. © 1987, Gordon and Breach Science Publishers S.A.