Chemical Reaction Engineering: Non Ideal Reactor

In general we study about ideal reactors like batch reactor, continuous stirred tank reactor (CSTR), plug flow reactor (PFR). Batch reactor is a unsteady state uniform reactor, PFR is a steady state non uniform reactor and CSTR is a steady state and uniform reactor. but in actual conditions the reactors deviate from their ideality. There are some reason like channeling, dead zone, bypass, back mixing etc. Due to these factors the behavior of an ideal reactor changes. The real flow pattern is found from the RTD (residence time distribution) curve. RTD shows the concentration of a tracer in output which was injected into the reactor. from the shape of RTD curve we can analyse the behavior of the reactor.

There are different models which can be used to find the non ideal behavior of the reactor like compartment model, dispersion model and Tanks in Series model. Dispersion model and Tanks in Series model shows the deviation from plug flow reactor. For an ideal plug flow behavior, the dispersion number (D/ul) will be 0 and the number of tanks in series will be infinite (∞). In PFR every cross section shows a CSTR so a PFR represent an infinite number of CSTRs connected in series.