Title: Pressure drop in PBR
Topic Covered: Chapter 4 Fogler, 3rd Edition
1. Mole balance
2. Rate law
3. Stoichiometry
4. Ergun equation
Summary: in gas phase reaction, the concentration of the reacting species is proportional
to the total pressure. So proper expression of concentration with pressure drop is the key
factor of calculation.
Tricks: 1. Using the pressure drop and Ergun equation to calculate 
2. Determining the relation between  and cross sectional area, particle diameter.
Question: #1
The irreversible gas phase reaction A+B2C is carried out in a PFR reactor. The
reaction is non-elementary in that it is first order in A and zero order in B. The feed is
equal molar in A and B, and the pressure at the entrance is 10atm and the pressure at the
exit is 2atm.
Additional information:
FA0=100 mol/s
K=1dm3/kg.s
CA0=1mol/ dm3
1) What is the conversion exiting the reactor?
2) If the flow were turbulent, what would be pressure drop if the cross sectional area
is increased by a factor 2 and the particle size decreased by a factor of 10? All
other conditions remain the same. (Hint: in the turbulent flow, the Ergun equation
neglects the part of 150(1-) /Dp. Reference: R.B.Bird, transport phenomena
(New York, Wiley, 1960), p. 200.)