Chemical Engineering July 2011 - 23

Fractionation Column
When troubleshooting the extractor
I
have an ongoing dispute with a longtime
colleague, Bob Miller. I said he
ruined my new safety boots. He said
he didn't.
Bob was a young, fearless distillation
engineer at a time when our extraction
engineer refused to take a trip to
Japan to inspect new trays going into
an old extractor. I called Bob into my
office and asked him to take the trip,
even with zero extraction experience.
Bob accepted the assignment, but worried
that he had no safety footwear. I
offered him my brand new safety boots.
I would have given him all of my shoes
if that is what it took to keep me out of
that old, dirty extractor.
When Bob came back from the installation
he handed me the boots
without blinking an eye. They looked
like they had been run over by an industrial
lawnmower. He insisted that
that is what they looked like when I
loaned them to him. I disagreed. His
tray installation had gone well - that
is what mattered most.
About two weeks later, Bob gave a
slide presentation to the entire distillation/extraction
group, describing
the installation. Half of the slides
were photographs of the feet of a
young, fearless distillation engineer
standing on trays inside the column.
The early photographs show bright
and shiny boots; the later photographs
showed the boots deteriorating
quickly. Bob had given me the
proof that I needed - I had indeed
given him good-as-new boots.
Just a few days later, on a Friday
afternoon, my supervisor came into
my office stating, " Our Japanese sales
office says that your extractor is not
working. You need to catch a flight
tomorrow. " I looked high and low for
Bob. He was nowhere to be found. I
decided that I needed to take this trip
myself. Troubleshoots sometimes last
weeks, or years. My flight to Japan
was fraught with anxiety. The chardonnay
tasted like glycol. I arrived at
the refinery on a Monday afternoon.
The production engineer led me into
the control room. The noise in there
was almost deafening. It was the butterflies
fluttering in my stomach.
I looked over the control board. The
unit was running very smoothly, but,
it was running at the old feed and
solvent rate. I asked their production
engineer, " What happens when you increase
the rates? " He said, " We don't
know. " I said, " You don't know? " Then
he replied, " Column pressure drop is
too high. " To that, I said, " These trays
are designed to operate at high pressure
drops. Just go ahead and increase
the rates. " " Really? " he asked. " Really, "
I answered.
The next day when I arrived in the
control room, the column was purring
at the as-designed rates, which were
about 20% higher than the old rates.
All of the control-room engineers and
operators were beaming. My review of
the control board showed that all was
well - very well. That night, the plant
manager took us all to a long, expensive
dinner, rife with sake, karaoke
and toasts to the extractors.
The first moral of this story: We all
get stuck in paradigms. The control
room personnel had convinced themselves
that the extractor was incapable
of functioning above a certain pressure
drop. In Bob's words, " Sometimes
after a column revamp, the operators
and technicians need to be retrained. "
The second moral of this story: Don't
loan Miller your safety boots.
■
For an excellent how-to article on tower inspections,
see pp. 44-48.
Mike Resetarits
is the technical
director at FRI
(Stillwater, Okla.;
www.fri.org), a distillation
research
consortium. Each
month, Mike
shares his firsthand
experience
with CE readers
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Chemical Engineering July 2011

Table of Contents for the Digital Edition of Chemical Engineering July 2011
