LearnChemE

#### Isothermal Continuous Stirred Tank Reactor (CSTRs) : Screencast

Describes the reasons for using a CSTR, presents the mass balances and discusses the unique aspects of CSTRs.

##### Important Equations:

Mass balances on an isothermal, steady-state CSTR for the irreversible reaction  $$A\rightarrow2B$$ whose rate is $$n^{th}$$ order in $$C_A$$.

$F_{A_{0}} – F_A – kC_{A}^{n}V=0$

in – out + rate of generation = 0

$F_{B_{0}} – F_B – 2kC_{A}^{n}V=0$

where $$F_A$$ and $$F_B$$ are the molar flow rates (mol/s) of A and B leaving the reactor, respectively, $$F_{A_{0}}$$ and $$F_{B_{0}}$$ are the molar flow rates (mol/s) of A and B entering the reactor, respectively, $$V$$ is the volume of reactor contents (L), $$k$$ is the rate constant, and $$C_A$$ is the molar concentration of A (mol/L).

These equations use the relations

$$F_A = vC_A$$  and  $$F_B = vC_B$$

where $$v$$ is the volumetric flow rate (L/s). For a liquid-phase system, $$v$$ can often be assumed constant.

$X = \frac{(F_{A_{0}}-F_A)}{F_{A_{0}}}$

where $$X$$ is the fractional conversion.

Percent conversion = 100*$$X$$