Optimization of space time at a glance

When you are well instructed you can give the following statement (or look at the following structogram):

For simple reactions, where the product formation is linked directly to the conversion, you can chose a conversion as high as possible and carry out the reaction in a not-back-mixed reactor type. For continuous operation you should take a TFR or a 'Cascade', for batch operations take the STR. We can call that:
'conversion orientated strategy'
(german: 'Umsatzorientierte Strategie')
For complex reactions you mostly need to carry out a controlling of concentration levels, which can be achieved by a selected pattern of back-mixing. You often have to 'design' a reactor combination. The choice is ruled by the kinetic behaviour of the reaction. We can call that:
'strategy of controlling concentration levels'
(german: 'Konzentrationsführungs - Strategie')

But !!

'maximum space time yield' means 'minimum space time' !
put yourself the question: is the formation of the wanted product linked obviously (and alone) to the conversion of the (reference) educt ?
yes:	no:
conversion orientated optimization	optimization with the necessity of controlling concentration levels
fixed rule: chose a high conversion ! best reactor: not back-mixed type: STR, TFR, depending on operation mode	no fixed rule: examine your reaction kinetics: what has to be done for maximum product formation ? Select an adapted contacting pattern But: the optimization concerns either product quantity and/or product formation rate Rem: maximum space time yield is for instance not necessarily reached with process parameters for maximum selectivity !!

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