Reactors with predominant overall circulation

The flow patterns in stirred tank reactors are complicated and are mostly difficult to model in a way that is practically applicable. Consequently, the quantitative effects of the rate of macro-mixing are difficult to estimate. There is one exception the situation where the reactor contents can be considered to be completely segregated (very slow micro-mixing). This situation, that has limited practical importance, was discussed in section 7.2.1.2. 

In many practical situations, the flow pattern in stirred reactors is turbulent. Then micro-mixing is always faster than macro-mixing, and the concept of complete segregation cannot apply. A qualitative estimate of the influence of imperfect mado-mixing can be based on the ratio between the reaction time and the macro-mixing time. 

In general, the reaction time is related to the relative rate of conversion of reactant (A) that is not in excess. It was defined in eq. (5.1) as follows 

In a stirred reactor, the macro-mixing time in turbulent flow is approximately equal to circulation time, see eq. (4.6)  

Imperfect macro-mixing in stirred tank reactors with turbulent flow can have three different effects  

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