<P> Plug flow reactors (PFRs) are reactors in which the reactants enter the reactor at one end and react as they move down the reactor . Consequently, the reaction rate is dependent on the concentrations which vary along the reactor requiring the inverse of the reaction rate to be integrated over the fractional conversion . </P> <Dl> <Dd> τ = C A O ∫ 1 (− r A) d f A (\ displaystyle \ tau = C_ (AO) \ int (\ frac (1) ((- r_ (A)))) \, df_ (A)) </Dd> </Dl> <Dd> τ = C A O ∫ 1 (− r A) d f A (\ displaystyle \ tau = C_ (AO) \ int (\ frac (1) ((- r_ (A)))) \, df_ (A)) </Dd> <P> Continuous stirred - tank reactors (CSTRs) are reactors in which the reactants continuously enter and leave a tank where they are mixed . Consequently, the reaction proceeds at a rate dependent on the outlet concentration . </P>

Holding time and space time for flow reactors