Ch E 441 - Chemical Kinetics and Reaction Engineering

1. Nonideal Reactor Modeling Ch E 441 - Chemical Kinetics and Reaction Engineering

2. Non-ideal Reactor Model Development Non-ideal reactor model must be mathematically tractable. realistically describe the characteristics of the nonideal reactor. not have more than two adjustable parameters. "Give me four adjustable parameters and I can fit an elephant; give me five and I can include his tail!” Fogler, p. 872 In complex systems, more than two parameters are acceptable and often necessary.

3. One Parameter Models One parameter in the model accounts for nonideality of the reactor. Parameter almost always evaluated by analysis of an RTD from a tracer test. One parameter nonideal CSTR models Reactor dead volume, VD Fraction of fluid bypassing reactor, f One parameter nonideal PFR models Tanks-in-series, n (number of tanks) Dispersion model, Da (dispersion coefficient)

4. Nonideal Reactor Model: Tanks-in-series Start with 3 tanks-in-series, generalize for n tanks The RTD is analyzed from a tracer pulse injected into the first of 3 equally-sized reactors in series. Using the RTD of Section 13.2, the fraction of material leaving the system of reactors between t and t+?t is