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Residence Time Distribution: Example Problems

Try to solve these problems before watching the solutions in the screencasts.

Example Problem 1

A slug of tracer was added to the feed stream for a stirred tank reactor, which was running at steady state. The tracer concentration was measured as a function of time at the reactor exit.

From these data, determine the average residence time for the reactor and the standard deviation of the residence time distribution.

Table for example problem in Residence Time Distribution module on LearnChemE.com
Example Problem 2

A non-ideal, continuous stirred tank reactor (CSTR) has the normalized response to a step function input of a tracer show in the figure. The step input starts at t=0.

a) Develop a 3-parameter model of this non-ideal reactor. The model can consist of ideal reactors, recycle, bypass, and hold-up.

b) Determine the values of the parameters for the model. The total reactor volume is 1.5 L and the inlet volumetric feedrate is 0.10 L/min.

c) Sketch the exit age distribution for the non-ideal reactor.

Graph for an example problem in Residence Time Distribution module on LearnChemE.com