Characterization of Agitation Intensity in Flocculation Processes
- 1 December 1986
- journal article
- research article
- Published by American Society of Civil Engineers (ASCE) in Journal of Environmental Engineering
- Vol. 112 (6) , 1158-1163
- https://doi.org/10.1061/(asce)0733-9372(1986)112:6(1158)
Abstract
It is common practice in the design and evaluation of flocculation processes to use the velocity gradient determined from the mean power input (reported as G) as the principal indicator of agitation intensity. This practice is objectionable because agitated vessels are notoriously nonhomogeneous, floc breakup occurs primarily in the impeller stream, and interparticle contact and subsequently aggregation require relative particle velocity, which in turn is caused by eddies of a particular scale or wave number. Data are presented in this work that show that the dissipation rate per unit mass in the impeller stream can exceed the mean value by two orders of magnitude or more. It is important that modeling efforts take these factors into account.Keywords
This publication has 7 references indexed in Scilit:
- Turbulent flow in stirred tanks. Part I: Turbulent flow in the turbine impeller regionAIChE Journal, 1985
- Is Velocity Gradient a Valid Turbulent Flocculation Parameter?Journal of Environmental Engineering, 1984
- Flocculation in stired tanksChemical Engineering Science, 1984
- LIQUID DISPERSION MECHANISMS IN AGITATED TANKS: PART I. PITCHED BLADE TURBINEChemical Engineering Communications, 1981
- Continuous flow stirred tank turbulence parameters in the impeller streamChemical Engineering Science, 1972
- Flow and turbulence in a stirred tankAIChE Journal, 1966
- Fluid flow in turbine-stirred, baffled tanks—IChemical Engineering Science, 1964