pwr_march-2024 - 36

MARNIE SURFACEBLOW
of ash, then dumping the contents into
the crucible.
" Now, story time, " she said. " We're
2. Marnie inspected the CEMS analyzers,
and all connections leading to and from the
stack and equipment. Source: POWER
certain to come.
She was wrong, however, as Stephenson
produced a printed document. " This
came with those new grommets. It says
installing them properly not only extends
the warranty but voids the prior one.
Note this new warranty is rather sparse,
saying nothing about the cabinet location, "
he countered.
Maya read the new evidence, then
turned to Mr. Tanaka. " You are aware of the
terms of this new warranty? " she queried.
" Yes, but all warranties we give say
the exclusive remedies are replacing
defective parts, not damages for lost
generation, " replied Tanaka. " We already
agreed to replace some failed
circuit boards. I could have my team
out here by tomorrow, if we can find
common ground. "
Maya frowned and responded, " I fear,
gentlemen, this has become a question
of legalities rather than engineering and
science. Thus, I must ... "
" Not so fast, my dear Watson! " cried
Marnie as she breezed into the room,
with Dan and Vi in tow. " It is absolutely a
question of engineering and science, as
well as history! Vi, could you kindly set
up the burner and crucible? "
Vi assembled a burner stand with
heat-proof wire mesh, placing a ceramic
crucible atop the mesh. A portable propane
torch was fixed underneath it, and
with the turn of a knob and a strike of the
torch flint, in less than a minute flames
on low heat were lapping the bottom of
the crucible.
" We shall now solve the case of the
mysterious CEMS cabinet ash! " Marnie
declared, dramatically producing her vial
36
all familiar with tin. After all, it's been
mined in Cornwall and Devon for more
than 2,000 years. It can be used for everything
from fine jewelry to mundane
solder. But don't let its flexibility fool
you; tin is temperamentally temperature
transitional. At room temperature, tin is
stable in what's called its 'beta' form.
Lower the temperature below roughly
13C, and tin's very crystal structure can
change to 'alpha' form. Normally, this
is glacially slow, if it happens at all, but
once it starts, it begins to fall apart with
what's called 'tin pest.' And, wow, is it
ever a pest! "
After pausing for air, Marnie contin " Interesting
historical sidebar-
ued.
there's still debate whether one reason
Napoleon's army suffered defeat during
his Russian winter campaign was the
crumbling of tin buttons holding the
troops' uniforms together. That may not
be proven, but in other cases, we do
have proof of tin pest causing havoc. Cathedral
organ pipes, beer cooling pipes,
Antarctic research equipment, shoot,
even the United States
tin
stockpile
started to be consumed by it just a few
years back, " she said.
Thrilled by Marnie's discovery, Maya
noted, " Mum, I remember from university,
this transformation is very destructive.
Alpha tin swells by 25% or more,
decaying into an ash-like substance, unless
you add lead, of course. "
Turning to Mr. Tanaka, Maya continued,
" Your company switched to leadfree
solder the year before the CEMS
were installed here. It was hailed in your
sales literature then for its environmental
benefit, " she noted.
" True, but we added bismuth to help
slow this transformation. That cannot be
the problem, " objected Mr. Tanaka.
" I beg to differ, sir, " said Maya. " Your
material safety data sheets show no
mention of bismuth. In fact, they say
you rely solely upon 'high-purity tin,'
which in fact is not a reliable deterrent
to tin pest. Even using bismuth, it takes
care to blend it properly as solder-especially
with smaller connections, like
circuit boards. Any area not protected
adequately and equally would start the
transformation. "
Mr. Tanaka was about to respond
when Marnie interjected, " The critical
component is temperature. Mr. Stephenson-Terry-when
you moved the CEMS
cabinets out into the yard, you took them
www.powermag.com
from a nice, snuggly, warm environment
and put them out in the cold. Remember,
if you're cold, your CEMS is cold. This is
why Boiler 22's CEMS is still running
smoothly. And come look, everyone,
here in the crucible! The mysterious ash
from the CEMS cabinet is now a wee
lake of molten tin! "
Amazed conversation filled the room,
as everyone crowded around the crucible.
Maya quietly sat in intense thought,
flipping through her tablet and making
notes. Barely five minutes later, she
called for order.
Case Settled
" My judgement as arbitrator is first, the
solder appears to have suffered from 'tin
pest,' which was rarely encountered at
the time as most solder prior used lead
to some extent. Second, the tin pest
was accelerated by placing the CEMS
cabinet outdoors, exposing it to a much
colder environment-again, something
not known to be a problem at the time.
Finally, some amount of force majeure
could apply, as the months of extremely
low temperatures recently were both
unexpected and likely played a precipitating
role, " declared Maya. " Since Tengu
Corporation has offered to replace
the failed CEMS parts for free, they will
do so and add an extended warranty
for five more years, which is contingent
upon the CEMS cabinets being moved
out of the elements and supplied with
electric heating, when needed, to a
temperature of 15C or greater. "
" I concur! " cried Marnie, as she
turned off the propane torch to let the
tin cool. Plant staff discussed plans
for moving the CEMS cabinet to a
warmer clime, and Mr. Tanaka was on
his phone ordering replacement gear.
Terry Stephenson approached Marnie
and Maya, and with deep respect in his
voice, said, " I know there's much to do
and agreements to hammer out, but
I will say I am impressed. Thank you,
both of you, so much. There aren't any
other hidden horrors lurking about, are
there? " he asked.
" I haven't found any large dogs painted
with phosphorus or anything like that,
but I did notice a hedgehog bearing a
certain wicked look, " Marnie laughed.
" Anyhow, let's talk about some scrubber
tuning services we could help you out
with, " she proposed, looking for her next
opportunity to problem-solve. ■
-Una Nowling, PE is an adjunct professor
of mechanical engineering at the
University of Missouri-Kansas City.
POWER | March 2024
http://www.powermag.com
pwr_march-2024

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