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*\(X\)