Particle Sedimentation in Model Tank and Crude Oil Storage Tank with Side-entering Mixer

Case of inserting angle θ= 20°

Abstract

The behaviour of the liquid in a side-entry mixing tank is very difficult to observe, and to date the flow pattern and particle sedimentation process in such tanks have not been conclusively clarified.
In the previous report the flow pattern and particle sedimentation process in a specially manufactured model mixer with a shaft entry angle θ=10° were observed and studied, with consideration also given to the effects of the handling conditions on the sweeping velocity of the mixer. Introducing sweeping-area formulas corresponding to the specified entry angle, the report also raised doubts concerning the sparse data presently available on these mixers.
In the present study the entry angle was increased to θ = 20° and the flow variations in the mixing tank, i.e., the flow pattern and particle sedimentation process, were investigated. The results indicated that at θ=20° the effects of the depth of liquid in the mixer were very significant and that the liquid depth performed an important role as a sludge sedimentation preventive measure in the oil storage tank or in other parts of the full-scale mixer. A comparative analysis of the model as well as two and then three full-scale mixers was performed, and conclusions were drawn from the results of the study.