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King Saud University
College of Engineering
Chemical Engineering Department
ChE 426: Heterogeneous Reaction Engineering
Summer 1430/1431 (2010)
QExam # 2
:
Prof. Ibrahim S. Al-Mutaz
A plant is removing a trace of Cl2 from a waste gas stream by passing it over a solid granular absorbent
in a tubular packed bed. At present, 63.2% removal is being accomplished, but it is believed that
greater removal could be achieved if the flow rate increased by a factor of 3, and the packed bed tube
length increased 50%. What percentage of chlorine would be removed under the scheme proposed?
(The chlorine transferring to the absorbent is removed completely by virtually instantaneous chemical
reaction).
Useful relations:
W‫אא‬
W‫א‬
King Saud University
College of Engineering
Chemical Engineering Department
:
ChE 426: Heterogeneous Reaction Engineering
Summer 1430/1431 (2010)
QExam # 2
Prof. Ibrahim S. Al-Mutaz
The catalytic reaction: A → B has been studied in a laboratory. The reaction can be modeled using first
order reaction kinetics: rA = -k CA. The lab has determined these kinetics from experiments using
compound A mixed with an inert. You have been asked to design an isothermal CSTR for a pilot plant
using this data. You suspect that there may be a catalyst poison in the actual feed and ask the lab to run
experiments using the feed for the pilot plant. They are astonished to find that the conversion of A in
the lab CSTR decays over a period of days according the attached figure.
Determine an expression for the activity of the catalyst. Assume that the concentration of poison is
constant. Also determine the conversion of A after 50 days.
Q0 = 1 L/s, FA0 = 10 mol/L s, k = 0.1 L/(kg cat s), W = 50 kg.