Performance of flow reactors at various levels of mixing

Abstract

Chemical flow reactors studied include models in which partial mixing and piston flow are present and others which involve partial mixing and short‐circuit. Mixing levels considered extend all the way between the extreme cases of tubular and continuous‐stirred tank reactors. Various orders of reaction are taken into account. The curves presented, obtained through analytical methods, show either the variation of conversion with mixing level at given values of residence time, or relative residence times for a given conversion. Graphical methods of solution are proposed. They involve, in part, a means of computation whereby the overall conversion for a number of reactors in series is obtained from the individual conversions. While isothermal conditions only have been considered, more interesting results are expected when other conditions are applicable, whether isothermal or not.

CFD Simulation of Vertical Linear Motion Mixing in Anaerobic Digester Tanks

“…Mixing Criteria. In 1959, Cholette and Cloutier derived integral models that described the time-dependent tank mixing in idealized reactors when influenced by imperfections in the mixing process (Cholette and Cloutier, 1959;Cholette et al, 1960). They created algebraic expressions that included the deleterious effects of partial mixing, short-circuiting of inlet flow directly to the outlet, the effects of piston (or plug) flow that ejects unmixed fluid from the outlet, and the effect of dead or nonparticipant regions on the outlet concentrations.…”

“…The final results are expressed in terms of measured mixing dispersion time, the time for the slug to mix uniformly throughout the tank such that the outlet tracer concentrations reach a maximum), a measured HRT (associated with the time constant for the exponential decay of outlet tracer concentrations), and the AV (ratio of nominal tank volume minus dead or inactive volume to nominal tank volume). Active volume is typically inferred from tracer washout tests by comparing actual decay of tracers at the digester exit to analytic or ideal decay rates (Cholette and Cloutier, 1959;Cholette et al, 1960;Monteith and Stephenson, 1981;Olivet et al, 2005;Wolf and Resnick, 1963).…”

Combined reactors: Formulation of criteria and operation of a mixed tubular semifluidized reactor

“…In an elaborate analysis of mixing, Cholette, Blanchet, and Cloutier (5,6) considered the case of a reactor which is partially mixed. The system was analyzed in terms of fully mixed and plug flow zones, and short circuiting was omitted from the analysis.…”

Optimización de la agitación de un digestor anaerobio mediante mecánica de fluidos computacional

“…Cholette y Cloutier (1959) y Cholette et al (1960) propusieron modelos integrales en los que se incluía la dependencia del tiempo de las condiciones de mezcla en reactores ideales.…”

“…Posteriormente, Wolf y Resnick (1963) propusieron una ecuación general basada en las ideas de Cholette y Cloutier (1959) y Cholette et al (1960):…”