LearnChemE

#### Recycle Mass Balances: Screencasts

A chemical reactor system is fed 100. kmol/h of reactant A, which is then mixed with a recycle stream. In the reactor, 60.% of A that enters the reactor is converted to product B. The mixture exiting the reactor goes to a separation unit where all of product B plus 20.% of A is removed, and the rest of A is recycled and mixed with the fresh feed. How many kmol/h of reactant A enter into the reactor?

We suggest that after watching this screencast, you list the important points as a way to increase retention.

Explains the steps in crystallization that includes an evaporator, a crystallizer and filter, and a recycle stream.

We suggest that after watching this screencast, you list the important points as a way to increase retention.

##### Important Equations:

$R = \frac{F_{T,R}}{F_f}$

where $$R$$ = recycle ratio,

$$F_{T,R}$$ = total molar flowrate (or mass flowrate) in recycle stream, and

$$F_f$$ = total molar flowrate (or mass flowrate) of fresh feed to system.

Overall conversion for a process with recycle

$overall \, conversion \, = \frac{F_{A0} -F_{A,f}}{F_{A0}}$

where $$F_{A0}$$ = molar flowrate of reactant $$A$$ into process (fresh feed, mol/h), and

$$F_{A,f}$$ = molar flowrate of reactant $$A$$ out of process (mol/h)

Conversion in reactor (single-pass conversion)

$reactor \, conversion \, = \frac{F_{A,m} – F_{A,outlet}}{F_{A,m}}$

where $$F_{A,m}$$ = molar flowrate of reactant $$A$$ in stream obtained by mixing fresh feed with recycle stream (mol/h), and

$$F_{A,outlet}$$ = molar flowrate of reactant $$A$$ in stream leaving reactor (mol/h).