Chemical Engineering July 2010 - 26

Fractionation Column
Seeking out difficult situations
I
n 1952, 37 companies established
Fractionation Research, Inc. (FRI).
Most of those original members are
now gone or absorbed by other companies.
Nevertheless, their goal was to
study distillation in columns having
diameters and heights that were similar
to industrial columns. The columns
of the world were getting larger and
more numerous and were too often
being designed using bench-top apparatuses
and rules of thumb. If it were
not for that early initiative, what we
know today about practical operation
of distillation columns would probably
be very different.
The original test columns were
located on a C.F. Braun property in
Alhambra, California. After about 35
years of very successful operation,
the columns were moved to the Oklahoma
State University (OSU) campus,
which is where they still reside.
History has shown that Oklahoma
weather is not as friendly to turnarounds
and operations as was California,
but at least the unit was not
moved to Fort Saskatchewan.
The FRI technicians and operators
are a very sturdy lot and often remind
me of a line from the cult-classic movie
" Repo Man " that goes something like
this, " Most people spend their entire
lives trying to keep out of difficult situations;
repo men spend their lives getting
into difficult situations. " The FRI
operators are the repo men of the distillation
world. For them, steady state is a
brief luxury. After steady state data are
collected, the operators change several
set points and then spend the next hour
or two settling the test column down.
During a typical two-week data collection,
the FRI operators flood the column
five times. Those flood points are often
dramatic, with liquid in the overhead
system and a lost bottoms level. Once a
flood point has been identified, the operators
start all over, collecting steady
state data at loadings like 20, 40, 60,
80, 90, 95 and 98% of flood. At 98% of
flood, pressure drops are high, tower
efficiency is low and true steadiness is
usually elusive. There is little free time
for coffee table chats in the FRI control
room. Compare this to a typical control
room where some operators silently
pray that a level alarm will go off during
their shifts - and give them something
to do. FRI's repo men spend their
shifts getting into difficult situations.
FRI operators do more than just
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control the test columns. They collect
fluid samples from the columns using
" bombs " at high pressures and vials at
low pressures. They run the gas chromatograph.
Every one or two months,
they shut the unit down, steam it out
and then air it out in anticipation of a
revamp. Trays, random packings and
structured packing all take regular
turns in the columns. Most of the revamp
work is effected using removable
heads at the tops of the two test columns.
FRI operators are lowered into
the columns using chairs and safety
lines and winches. Random packings
are removed and installed using buckets.
Structured packings are removed
and installed using thick gloves. Tray
installations require that tabs be
welded to the inside of the shell, with
removable expansion rings being used
above the tabs.
None of this work is easy, especially
A Watts Water Technologies Company
26 CHEMICAL ENGINEERING WWW.CHE.COM JULY 2010
Circle 27 on p. 58 or go to adlinks.che.com/29252-27
during Oklahoma winds storms, yet the
operators' biggest complaint is the singing
of the other operators. With that,
FRI salutes operators everywhere. ■
Mike Resetarits
resetarits@fri.org
http://adlinks.che.com/29252-27 http://WWW.CHE.COM
Chemical Engineering July 2010

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