CFD Analysis of the Mixing Behaviour of a Stable Stratification in a Cylindrical Tank With a Side-Entry Mixer

Abstract

Blending of liquids with different densities is often performed by the oil industry. Side-entry mixers are frequently used to homogenize the contents of storage tanks. Normally, empirical correlations are used to determine the mixing time of these mixers. The objective of the work, discussed in this paper is to establish the potential of CFD in determining these mixing times. A buoyancy extended standard k-ε model has been used to model the mixing behaviour in a tank containing two miscible liquids of different density, which are stratified before the mixer is switched on. The agreement with the experiments was not good: the model in some cases underestimated the mixing time by an order of magnitude. In another attempt, LES technique was used to model this problem. The agreement with the experiments became better but still the mixing time in the low Froude number range was seriously underestimated. Work is in progress to refine the LES simulations.

Experimental and Numerical Studies of the Flow Field in a Stirred Tank Equipped with Multiple Side‐Entering Agitators

“…Dskhel et al [18] used CFD to predict the homogenization time of a large-scale oil storage tank equipped with a sideentry marine-type mixer, and the results showed good agreement with experimental data. However, the agreement found by Van Looy et al [19] was not good, with the CFD model in some cases underestimating the mixing time. Ford et al [20] and Gomez et al [21] studied the mixing and the flow field in a rectangular vessel equipped with a side-entering agitator, which are usually used in the pulp and paper industry, by applying CFD and PIV methods, and the results agreed quite well.…”