* "From the residence time distribution we get information on the characteristics and quality of macro-mixing" (contacting pattern).
* First of all let us explain how
we define the term 'macro-mixing' in this course, because there are different
interpretations in literature. Let us take all macroscopic effects that arise
from the mixing procedure (stirrer, hydrodynamic flow) as
'macro-mixing'. The most reasonable english term is in the author's
opinion: 'contacting pattern'. These macroscopic effects can be made
visible for the bare human eye (taking colours or visible particles) without
'physical aid' (as for example the Tyndall effect taking the stray light for
the detection of particles we don't see). Examples for macro-mixing effects
are: the more or less ideal mixing in a 'stirred tank reactor', the plug flow
and axial dispersion in a tubular reactor, bypass flows and capacitive holdups
within reactors, etc. Please don't take the term macro-mixing for the term
'macrofluid' : macrofluid is a synonym very often taken in english
literature for a segregated fluid. Segregation concerns with fluid
properties, which should better be related to the topic that we call
'micro-mixing' in this course.
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* The characteristics of macro-mixing means that we see
from the residence time distribution what basic type of reactor or reactor
combination we encounter (principally). We also could say: we see the amount of
back-mixing in our spectrum, or alternatively: the smaller the spectral peak of
the RTD the 'less back-mixed' the reactor. Remember: the CSTR is totally
back-mixed, the TFR is 'totally not back-mixed'.
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* The quality of macro-mixing means that we see how close our reactor works to the ideal type. Remember for example that CSTR-rectors with bypasses show an additional 'peak' (see snapshot) in their normal spectrum.
A related question:
Can you give some examples for real behaviours of
macro-mixing and of combinations of ideal reactors
that are able for modelling these real types?
Not at all? Then take
this:
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