Conversion versus Reactor Volume for CSTR and PFTR

reactor type

CSTR

PFTR

n

B

1

The Demonstration plots the conversion versus reactor volume for either a CSTR (continuous stirred-tank reactor) or a PFTR (plug flow tubular reactor). The volume (in liters) required to obtain 90% conversion in the reaction

A→

n

B

is indicated by the green dot in the figure. The reaction takes place in the gas phase with a rate constant

k=0.5

-1

min

. The feed flow rate is

v

0

=4liters/min

and corresponds to a composition such that

C

A0

=2moles/liter.

This is a high-pressure gas-phase reaction since

P

A

=

C

A

RT=49atm

. You can set the value of

n

B

. Based on the present calculation, you can draw the following conclusions: (1) to achieve the desired conversion, the required reactor volume is larger for the CSTR than the PFTR; and (2) if the reaction reduces the number of moles (e.g.,

n

b

=0.5)

, the required reactor volume is smaller. For example, if

n

b

=2

, the reaction produces more moles, thus diluting the reactant

A

and causing the volume to be larger.