Experimental Measurement of RTD

This provides an important check on the accuracy of the pulse-tracer experiment, since the area under the response curve represents the same quantity, if the tracer is completely accounted for by a material balance. Thus, 

3-2 (frequent sampling may be required, particularly to capture a peak concentration). 

A tracer study mas7 use a step increase followed at a later time by a step decrease the transient responses in the two cases are then checked far consistency. When considered separately, the washout technique has advantages less tracer is required, and it avoids having to maintain a steady-state value of cA in for a lengthy period. 

In comparison with a pulse input, the step input has the following advantages  

Accurate determination of RTD in a vessel requires proper selection and introduction of a tracer. Here, we consider characteristics and examples of tracers. 

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We first describe features of nonideal flow qualitatively, and then in terms of mixing aspects. For the rest of the chapter, we concentrate on its characterization in terms of RTD. This involves (1) description of the experimental measurement of RTD functions (.E, F, IF), and development of techniques for characterizing nonideal flow and (2) introduction of two simple models for nonideal flow that can account for departures from ideal flow. 

A mathematical model for nonideal flow in a vessel provides a characterization of the mixing and flow behavior. Although it may appear to be an independent alternative to the experimental measurement of RTD, the latter may be required to determine the parameters) of the model. The ultimate importance of such a model for our purpose is that it may be used to assess the performance of the vessel as a reactor (Chapter 20). 

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