Fluent - Flow Modeling Examples - Residence Time Distribution in CSTR’s



	Residence Time Distribution in CSTR's

In CSTRs, the flow patterns are not idealized plug or mixed flow but tend to involve backmixing and channeling of liquid and/or the existence of stagnation zones in the reactor. In scale-up, it is possible to determine the reactor performance by quantifying the "non-ideality" of the flow. This is done by evaluating the exit age distribution function, E, also referred to as the residence time distribution, or RTD.

Multistage reactor performance can be evaluated using CFD.
The residence time distribution was determined by modeling the time dependent transport of a neutrally buoyant tracer species. The concentration of the tracer at the reactor exit was monitored over time. The CFD results can be benchmarked against the pilot plant and then used to model the scaled up, production capacity reactor.

The transient behavior of the tracer dispersion through the multistage reactor is captured.
The nondimensional concentration of the tracer can be monitored at the outlet or in-between the stages as a function of time.

Residence Time Distribution in CSTR's