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Flow pattern transitions and flow pattern detection of dilute solid–liquid mixtures in horizontal concentric and eccentric annulus

Kelesidis Vasilis, Bandelis G.E.

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URI: http://purl.tuc.gr/dl/dias/86C1489D-BBD0-41D1-B2F3-283115A2EDFA
Year 2005
Type of Item Conference Full Paper
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Bibliographic Citation V.C. Kelessidis and G.E. Bandelis, "Flow Pattern Transitions and Flow Pattern Detection of Dilute Solid–Liquid Mixtures in Horizontal Concentric and Eccentric Annulus", presented at 7th World Congress in Chem. Engineering, Glasgow, 2005.
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Summary

In this paper experimental results are presented for flow patterns observed when dilute solid–liquidmixtures flow in horizontal concentric and eccentric annulus. This configuration occurs very frequently inoil well drilling and production but the results are equally applicable for mineral, wood-pulp, wasteprocessing and for slurry transport with pipe conduits. The flow patterns created when two phase solid –liquid mixtures flow in conduits depend on several parameters like flow rates, conduit shape and size, fluidand solid properties and conduit inclination. Proper identification of the particular flow patterns leads tobetter estimation of the main parameters of interest, pressure drop and heat and mass transfer rates.Experiments were performed in a flow loop with a transparent concentric and 100% eccentric annulus, 5mlong, with outer diameter of 7.0cm and inner diameter of 4.0cm, for a range of liquid flow rates, 0 –500lpm, using two Newtonian liquids (1cp and 6.79cp viscosity) and one non-Newtonian liquid (apparentviscosity of 50cp at 170s-1). The solids are 2mm glass spheres with sphericity close to one. The flowpatterns at various liquid flow rates and experimental conditions were observed visually and by videomonitoring equipment and were analyzed to produce flow pattern maps. The main parameters affectingthe transition to the particular flow pattern are presented and the conditions for transition are discussed.Bed erosion tests indicated different erosion mechanisms and erosion velocities for the three liquidsstudied with the liquid viscosity playing a major role. Furthermore, a method and a system are presentedfor flow pattern detection from pressure drop measurements and the positive implications for real lifesituations are discussed.

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