Isothermal Plug Flow Reactors (PFRs): Example Problems

Try to solve these problems before watching the solutions in the screencasts.

Example Problem 1

Develop equations to determine plug flow reactor size for 50% conversion of reactant A. The reaction is gas-phase, in an isothermal PFR, and is at 5.0 atm pressure and 55°C. The volumetric flow rate of the feed is 50 L/min.

A + 2B → 2D    rA = -2.5CA0.5CB mol L-1 min-1

Feed mole fractions: yA = 0.2, yB = 0.5, yC = 0.3 (C is an inert.)

Example Problem 2

An isothermal plug flow reactor is used for the reaction 10A(g) → B(s). The rate constant is 0.30 mol-1. Small solid particles of product B are entrained in the gas flow. Because of the density of the solid particles is orders of magnitude larger than the gas density, the solid is assumed to occupy an insignificant volume compared to the gas. The feed of pure A is at a pressure of 10 bar, a temperature of 450 K, and a flow rate of 120 mol/min. The reactor volume is 100 L. Determine the exit conversion at these conditions.