Observations on transient testing techniques. An example of a tracer test

3 OBSERVATIONS ON TRANSIENT TESTING TECHNIQUES. AN EXAMPLE OF A TRACER TEST 

The five transient testing techniques outlined above are not independent but simply alternatives by means of which RTDs and system dynamics can be studied in particular situations, one or other method may be preferred. Some of the relationships between these different techniques are discussed in refs. 22, 24 and 25. 

So far, all of the material presented has been discussed in the absence of any numerical examples. At this point, we introduce such an example the initial calculations will be used subsequently as a basis for further examples and, in this way, it will be possible to see how raw tracer data can be processed. Eventually, predictions will be made of what conversion can be expected when a reaction with known kinetics takes place in the system from which the tracer information was gathered. In the examples which involve tracer data, it should be emphasised that only in the most carefully engineered equipment could data of the accuracy quoted be obtained. In real situations, tracer mass balances may close inadequately and predictions of reactor performance must be treated with appropriate caution. 

Imagine that a reactor is operating in the steady state with a constant throughflow, Q, of 3.7 dm min. At the reactor inlet, 50 g of concentrated dye are instantaneously injected. The outlet concentration of this tracer is detected and recorded as a function of time. Steady-state calibrations of the dye-detecting system show that its sensitivity is essentially constant and equal to 3.88 mV (g dye dm over the range of dye concentrations encountered. The data in Table 1 is collected. 

Data for recorder output following dye injection (Example 1) 

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