Pressure Drop in Packed Bed Reactors: Interactive Simulation

This simulation was prepared using Mathematica. Download the free Wolfram player, and then download the simulation CDF file (link given below or click on figure to download). A screencast below shows how to use the simulation.

A first-order, irreversible, gas-phase reaction A → B takes place in two isothermal, packed-bed catalytic reactors; they have the same diameter but different lengths (14 m and 21 m). Only A is fed to the reactors. The inlet pressure is the same for each reactor; the outlet pressure changes when particle diameter is changed with the slider, but each reactor has the same outlet pressure. As a result, the inlet molar flow rate of A is lower for the longer reactor. Show plots of conversion, pressure, reactant molar flow rate, and volumetric flow rate as a function of distance down the reactor for both reactors with buttons. The Ergun equation is used to model the pressure drop.

Try to answer these questions before determining the answers with the simulation. We suggest that you write down the reasons for your answers.

  1. As the size of particles in a packed bed increases, does the pressure drop increase, decrease, or essentially not change?
  2. For two reactors of the same length but different pressure drops, will conversion be higher or lower in the reactor with the larger pressure drop? Why?