Density Change Cannot be Ignored in a Plug Flow Reactor
This simulation shows the effect of ignoring density change due to mole change in a gas-phase reaction when calculating conversion in an isothermal plug flow reactor (PFR). A second-order, gas-phase reaction (A → 2B + C) takes place in an isothermal, isobaric PFR. Because of the mole increase in the reaction, the volumetric flow rate increases down the reactor. This decreases the residence time compared to a reaction with the same kinetics but no change in the number of moles, and thus conversion decreases. This decrease in conversion can instead be viewed as a decrease in the reactant concentration due to the increased number of moles. Reactor models that account for the density change by calculating the changing volumetric flow rate (blue line) can be compared to models that assume constant volumetric flow rate (dashed black line). By adjusting reactor volumes, the models can be compared (1) at the same reactor volume and observing the difference in conversion, or (2) at the same conversion and observing the difference in reactor volumes.
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This simulation was made at the University of Colorado Boulder, Department of Chemical and Biological Engineering. Author: Rachael L. Baumann
View the source code for this simulation