The General Mole Balance & Ideal Reactors

Example of Reactor Design FA0 FA In – Out + Generation = Accumulation What do we do with this term?

As DV goes to zero and M goes to infinity: The Generation Term FA0 FA Divide reactor into little regions, small enough that intensive variables (CA, T, P) do not vary within. As DV goes to zero and M goes to infinity:

The General Mole Balance Let’s apply it to the three ideal reactors!

Batch Reactor Perfectly mixed No flow in or out

Batch Reactor Perfectly mixed No flow in No flow out

And if the volume is not a function of time (constant) Batch Reactor And if the volume is not a function of time (constant)

Continuous Stirred Tank Reactor CSTR Perfectly mixed Steady state

CSTR Perfectly mixed Steady state

CSTR

Plug Flow Reactor PFR No radial gradients – only axial Steady state

PFR Steady state This is the integral form. Often the differential form is more useful. Take the derivative with respect to volume of each term.

Derivative of a constant is just 0 PFR Derivative of a constant is just 0 rA

Here is where some complication sets in: PFR Here is where some complication sets in: