ASEE Summer School for ChE Faculty
July 2002
CU Boulder
Spreadsheets Across the Curriculum – Workshop 2
Ammonia Flowsheet
from Felder & Rousseau, Problem 62, page 173.
The fresh feed to an ammonia production process contains 24.75% (mole) nitrogen, 74.25%
hydrogen, and the balance inerts. This feed is combined with a recycle stream containing the
same species, and the combined stream is fed to a reactor in which a 25% single-pass
conversion of nitrogen is achieved. The products pass through a condenser in which essentially
all the ammonia product is removed, and the remaining gases are recycled. However, to prevent
build-up of the inerts in the system, a purge stream must be taken off. The recycle stream is to
contain 12.5% (mole) inerts. Develop a spreadsheet with the material balance calculations for
this process. Calculate also the overall conversion of nitrogen, the purge ratio (moles purge gas /
mole of gas leaving the condenser), and the feed ratio (moles fresh feed / mole fed to the
reactor).
Purge
Recycle
Feed
Reactor
Condenser
Ammonia Process
Product