Allgemeing�ltige Aussage zur Mindest-R�hrerdrehzahl beim Suspendieren
Chemie Ingenieur Technik (Impact Factor: 0.66). 01/1985; 57(8):692-693. DOI: 10.1002/cite.330570811
ABSTRACT No abstract is available for this article.
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ABSTRACT: Suspension of solids in stirred tanks – Comparison of different calculations. The suspension of solids in stirred tanks has been the subject of various investigations over the last three decades. Though many equations for the calculation of the critical impeller suspension speed were derived and published during this period of time no conclusive descriptions have been achieved. As a consequence, serious problems arose concerning the scaling-up of the mixer, since the various equations led to completely different designs. Over the last few years new physical models have been developed to improve on this point. These models aimed to reach a better description by considering the fluid-dynamic process more accurately. This survey presents the actual state of investigation by systematically comparing the results of the latest models. Careful consideration of the experimental conditions gave fairly consistent results. The decisive problem of the scale-up procedure, however, remains unsolved.Chemie Ingenieur Technik 11/1988; 60(11):822-829. DOI:10.1002/cite.330601104 · 0.66 Impact Factor
Article: Suspension of Solid Particles[Show abstract] [Hide abstract]
ABSTRACT: This paper deals with the prediction of the impeller speed required for complete suspension of solid particles. Based on the inspection analysis of the governing equations, the dimensionless equation expressing such impeller speed was proposed. The specific forms of this equation were determined experimentally for a six-pitched blade turbine for solid concentrations of 2.5 and 10% by volume. Four different hydrodynamic regimes were observed depending on the relative particle size and Reynolds number values. In view of our results the weaknesses of existing theories and correlations were shown and discussed.Chemical Engineering Science 07/1994; 49(14-49):2219-2227. DOI:10.1016/0009-2509(94)E0029-P · 2.61 Impact Factor
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ABSTRACT: By means of considerations, experimental results as well as high-speed photographs it is shown that in flotation machines the zone of high local energy dissipation, i.e. the impeller stream, is the active region for the realization of the microprocesses bubble dispersion and particle-bubble attachment. Because of the pressure differences as well as the turbulent pressure fluctuations existing there, it is not unlikely that gas precipitation influences the attachment events substantially. Outside of the impeller stream, the local energy dissipation is so far reduced below the mean dissipation ϵ = Pm that the preconditions for realizing these microprocesses, which are controlled by turbulence, are no more met. However, these phenomena call for further explanation. It seems to be very likely that the widespread and too simplistic ideas on the course of the particle-bubble attachment need substantial adjustments and/or completions. Moreover, the consequences which result from these findings for the hydrodynamic scale-up are discussed.International Journal of Mineral Processing 02/1998; 52(4):245-259. DOI:10.1016/S0301-7516(97)00070-7 · 1.46 Impact Factor
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