Study on Solubility of Hydrophobically Associating Polymers Using Double Agitators

Abstract

Mechanical agitators are widely used for accelerating the dissolution of hydrophobically associating polymers. However, the polymer dissolution process is nonuniform, changing from multiphase low viscosity to single-phase high viscosity. A single agitator, either a hydrofoil for low viscosity or an anchor type for high viscosity, cannot be optimized for the polymer dissolution process. In this paper, the use of double agitators for the polymer dissolution process is investigated. The double agitators are composed of an inner hydrofoil impeller, suitable for low viscosity fluids, and an outer anchor and frame type impeller, suitable for high viscosity fluids. In addition, different kinds of combinations and interactions between the two agitators are studied. The experimental process is also simulated using the CFD software package FLUENT, and the results are compared with experimental results. The predicted power consumptions are consistent with the experimental results. The experimental and numerical results show that different agitators have different effects during the polymer dissolution process. Using the same rotation direction for the inner and outer impellers increases the overall circulation in the stirred tank and accelerates the dissolution of the hydrophobically associating polymer. The inner impeller with down-pumping is more effective than that with up-pumping in the double agitator system.