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Dayton, OH, United States

Myers K.J.,University of Dayton | Herr J.P.,University of Dayton | Janz E.E.,Chemineer Inc.
Canadian Journal of Chemical Engineering | Year: 2011

Solids suspension using an angle-mounted axial-flow impeller in an unbaffled tank relies on proper placement of the impeller in the vessel such that swirling flow does not occur. Even with proper placement, the just-suspended speed of an angle-mounted agitator is often 75% higher than with vertical mounting on the centreline in a baffled tank, leading to torque and power requirements that average more than twice and five times higher, respectively. Angle-mounted turbulent power numbers of axial-flow impellers are generally similar to, but lower than the corresponding power numbers with vertical mounting on the centreline of a baffled tank. © 2011 Canadian Society for Chemical Engineering.


Fasano J.B.,Mixer Engineering Co. | Myers K.J.,University of Dayton | Janz E.E.,Chemineer Inc.
Canadian Journal of Chemical Engineering | Year: 2011

The effects of impeller blade width and blade number on the gas dispersion behaviour of disc impellers with semicircular blades have been characterised. Increasing blade width or number increases the ungassed turbulent power number and reduces the drop in power draw upon gassing. While speed and power required for gas dispersion decrease with increasing blade width and number, the dispersion torque is relatively independent of these impeller geometric characteristics. A three-blade impeller exhibits the worst gas dispersion characteristics, while a four-blade impeller with non-uniform blade spacing outperforms a four-blade impeller with uniform blade spacing. © 2011 Canadian Society for Chemical Engineering.


Fasano J.,Mixer Engineering Co. | Janz E.E.,Chemineer Inc. | Myers K.,University of Dayton
International Journal of Chemical Engineering | Year: 2012

A thorough review of the major parameters that affect solid-liquid slurry wear on impellers and techniques for minimizing wear is presented. These major parameters include (i) chemical environment, (ii) hardness of solids, (iii) density of solids, (iv) percent solids, (v) shape of solids, (vi) fluid regime (turbulent, transitional, or laminar), (vii) hardness of the mixer's wetted parts, (viii) hydraulic efficiency of the impeller (kinetic energy dissipation rates near the impeller blades), (ix) impact velocity, and (x) impact frequency. Techniques for minimizing the wear on impellers cover the choice of impeller, size and speed of the impeller, alloy selection, and surface coating or coverings. An example is provided as well as an assessment of the approximate life improvement. Copyright © 2012 Julian Fasano et al.


Myers K.J.,University of Dayton | Jones J.K.,University of Dayton | Janz E.E.,Chemineer Inc. | Fasano J.B.,Mixer Engineering Co.
Canadian Journal of Chemical Engineering | Year: 2014

With the impeller placed low in the tank (C/T=1/3), turbulent blend times produced by radial-flow and down-pumping axial-flow impellers generally increase slowly with increasing liquid level in shorter batches (Z/T<1), but increase dramatically in taller batches (Z/T>1). The turbulent blend times produced by up-pumping axial-flow impellers increase slowly with increasing liquid level across the entire spectrum of liquid levels that were studied (up to Z/T=1.75). This can lead to down-pumping blend times that are twice as long as those with up-pumping operation. These differences can be explained by differences in the velocity field in the agitated vessel. Further, the down-pumping mode can produce blend times in tall tanks that are comparable to those of the up-pumping mode if the down-pumping impeller is placed high in the batch such that its discharge flow is directed into the bulk of the liquid. © 2013 Canadian Society for Chemical Engineering.


Myers K.J.,University of Dayton | Janz E.E.,Chemineer Inc. | Fasano J.B.,Mixer Engineering Co.
Canadian Journal of Chemical Engineering | Year: 2013

Data taken with six solids at numerous Zwietering loadings ranging from near zero to 67 have been used to determine the just-suspended speed Zwietering loading exponent (Njs∝Xn where n is the Zwietering solids loading exponent). When only the loadings range similar to that studied by Zwietering [Zwietering, Chem. Eng. Sci. 1958, 8, 244] is considered (0

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