POWER September 2023 - 35

MARNIE SURFACEBLOW
mills. We add coal at the bottom or top
mills to help combustion. Each silo holds
16 hours of coal, but under eight hours'
worth of pellets, even at half plant output.
Our main conveyors run almost constantly,
mostly moving pellets. Our coal
bins sit filled to the brim unless we have
an emergency call for power. "
" You no longer require the coal mills
for combustion stability? " asked Maya.
Shaking his head, Preston replied,
" We upgraded systems and controls,
and monthly fine-tune and maintain the
mills, so things mostly work out-unless
it rains on the pellets, and then we will
bring in the coal mills. But let's let Jeff
show you our biggest problem, and it's a
doozy, folks! "
Jeff reached into a duffel bag and retrieved
two massive steel chain links that
were twisted and broken. " This plant
was built with a continuous scraper conveyor
to feed the fuel silos. It's basically
a drag-chain with steel blades pulling the
fuel along a steel trough to drop it down
the five silo hatchways. The first hatchway
feeds silo #1 that feeds the lower
coal mill, and the last hatchway in the run
feeds silo #5, the upper coal mill. Pellets
are sent through the middle three hatchways. "
Jeff paused and shook his head.
" Ladies, I've worked here nigh on 40
years and never seen any conveyor problem
like this. During the two-mill tests,
I saw high conveyor motor amperage,
and running three pellet mills we hit the
amperage limits at least once a day. And
then two weeks ago, two of our drag
chain links broke! We fixed them, and
last week another link broke. This thing's
so old these links are custom-crafted,
and we are out of spares. "
" Also, " Annik leaned in, " last week,
during feeder cleaning, we found small
steel shavings mixed in with the pellets.
It looks like it's coming from the conveyor
trough, but why? The pellets aren't
that abrasive. So ... what do you think? "
From Family Lore to Engineering
Solution
The group looked to Marnie and Maya,
waiting for an answer. Marnie held her
coffee cup with deep reverence, gazing
down into its milky depths as if reading
the plant's fortune. Knowing her boss's
mind was running full-tilt, Maya started
asking
operations
and
maintenance
questions, logistics on getting a plant
distributed control system data dump,
and about the water mist system. All
questions soon had answers, and Maya
had no choice but to nudge her boss and
September 2023 | POWER
ask, " Ma'am? What is it you ponder? "
" I was thinking of the stories told by
my family. I wanted to be a writer, an artist,
a musician, and many other things,
but I listened to every story of engineering
exploits and derring-do, and I remember
them all. " Marnie turned toward Maya
and tapped her own head. " I was recalling
a story from Grandpa Marmaduke.
He was on a Mississippi steamboat pleasure
cruise, playing poker and drinking his
sandpaper gin, until he had to help fix an
anchor chain that kept mysteriously breaking.
And then in another story ... "
Suddenly, Marnie stood and addressed
the room, green eyes flashing
with inspiration. " Memory and experience
are invaluable, and when combined
with measurement, analysis, and applied
research solutions, it creates the noble
and honorable practice of engineering! "
Silence reigned as Marnie continued.
" And thus, your stories brought forth
from the depths of my mind another
tale, and led to a theory. I have a shopping
list, but since my personal shopper
is about 2,000 miles away, I must
instead ask you good folks for help. We
need laser levels and silo weight tracking
charts. I want to see the metal shavings
mixed with the pellets, and all data
from the two days prior to each scraper
conveyor failure. Maya, let's start looking
through the data, then armed with some
lasers-Wow, that sounds really cool!-
we'll inspect the scraper conveyor in its
natural habitat. "
Finding Order Amid the Chaos
Plant data collection was managed by
dozens of systems, from circular chart
pen-and-paper recorders to broadspectrum
wireless transceivers. Even
Maya, whom Marnie sometimes called
" the Devi of Data, " struggled to weave
her virtual tapestry of daily plant performance.
" Ma'am, I confess, I am feeling
like a translator at the United Nations
who was assigned all the wrong countries.
The plant documentation, it is
English, French, at least one First Nations
language, and I believe this is ...
Portuguese? But worst of all, ma'am,
every microcontroller is set to a different
time-sometimes a different date
or year! No two of them agree. Perhaps
they should synchronize with the phases
of the moon! "
" Don't you dare suggest that, " hissed
Marnie. " I once had to set a continuous
emissions monitoring system to use the
lunar calendar. It's required, really, for
power plants operated by werewolves. "
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Stunned at being caught off-guard by
Marnie's deadpan, which normally Maya
was used to, she laughed refreshingly,
and said, " Exceedingly good, ma'am. "
Setting down a bag full of borrowed laser
levels, Marnie could no longer control
herself, and clapped her hands with glee.
" Have you looked around this place? This
plant is positively steampunk! One conveyor
control box uses vacuum tubes
AND gutta percha wiring! I found five
oil pressure gauges working off Bourdon
tubes! Their feedwater heaters have
bronze Art Deco isolation valves! This
plant is so old, it's been retro twice! "
Maya sighed and pinched the bridge
of her nose. Marnie, realizing her exuberance
was out of place, quietly said,
" I have all the gear we need. How can
I help? "
Maya passed her laptop over, and replied,
" Ma'am, please examine these
data trends and see if you are finding
the same patterns as I? " Giving the data
her full mental focus, Marnie checked every
calculation, then looked up, her face
showing controlled alarm. " Is it safe? "
Giving Marnie " The Look, " Maya said,
" Ma'am, if I did not believe so, would
I be calmly sitting here? " Sheepishly,
Marnie returned to reviewing, then gave
a quick nod. " Everything lines up. Very
well done! You did the improbable. "
" Do you not mean the impossible? "
asked Maya.
" Well, you did it, thus by definition it
wasn't impossible, " replied a beaming
Marnie. Maya shook her head. " You're
impossible. "
Illuminating the Problem
An hour later, they joined the plant staff
in the scraper conveyor room over the
fuel silos. Preston greeted them, wiping
a mixture of biomass and coal dust from
his face. " We found signs the scraper
conveyor was, well, scraping the fuel
trough, mostly between silos 2 and 4.
Jeff says he's never seen the like! "
Maya took notes and interviewed coal
maintenance personnel, while Marnie,
eager as a kid on Christmas Day, was
running about setting up laser levels (Figure
2). " Maya! Remind me to buy some
of these! In green! "
" Green laser light, ma'am, or green in
housing color? " Maya asked distractedly.
" Both! " was Marnie's enthusiastic reply.
Maya confirmed the level placement,
making one final adjustment, while Marnie
stationed staff at each laser level.
She returned to the center of the conveyor
room and yelled, " Fiat lux! "
35
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POWER September 2023

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