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Konzept zur Maßstabsübertragung beim Suspendieren im Rührbehälter
Author(s) -
Kraume Matthias,
Zehner Peter
Publication year - 1995
Publication title -
chemie ingenieur technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.365
H-Index - 36
eISSN - 1522-2640
pISSN - 0009-286X
DOI - 10.1002/cite.330670304
Subject(s) - mechanics , turbulence , impeller , suspension (topology) , laminar flow , range (aeronautics) , propeller , flow (mathematics) , agitator , limiting , control theory (sociology) , power (physics) , thermodynamics , physics , materials science , mathematics , engineering , mechanical engineering , computer science , marine engineering , control (management) , artificial intelligence , homotopy , pure mathematics , composite material
Concept for Scale‐up on Suspension in a Stirred Tank. The relationships derived for the suspension of solids in a propeller loop can be applied to corresponding processes in a stirred tank by means of analogy considerations. Accordingly, the ratio of stirrer power to slip power of laminar flow state is inversely proportional to the vessel diameter. In contrast, the power ratio remains constant in turbulent flow. There is a pronounced transition range between these two limiting states. The author's own experimental studies performed over a wide range of Re numbers for the recycling flow confirm this relationship. The observations presented explain why numerous authors have determined scale‐up rules lying between these two extremes. The experiments shows that the power input for suspension is always significantly greater than the slip power. Under otherwise identical conditions, the necessary stirrer power is smaller by a factor of three for a propeller stirrer than for a disk impeller. The suspension of small solids concentrations can also be approximated by the flow model presented. The somewhat different physical relations valid in this case are substantiated by the author's experiments. The model also provided information relevant to scale‐up when the particle properties are unknown. This is demontrated for an example in a 21 m 3 vessel.