POWER September 2015 - 47

FUNDAMENTALS
within their owner's generating portfolio.
To avoid obsolescence, improvements related
to fuel flexibility may include upgrades of
existing capital equipment, new and higher-capacity
equipment, new generation technology
(such as installing a coal additive system or flue
gas sorbent injection system), or improved operations
via better monitoring and diagnostics
hardware and software. And although the U.S.
Supreme Court may have set aside the Mercury
and Air Toxics Standards (MATS) with its ruling
in Michigan v. EPA, very few believe that
the progression of environmental regulations
on coal power plants is at an end,
Fuel Flexibility with Coal Alone
As mentioned, stack emissions and other environmental
regulations are almost certainly
not going to be loosened in the future; rather,
the trend is clearly the reverse. Increasing
fuel flexibility can help one prepare for future
emissions regulations while also providing
operations benefits.
One example comes from an Illinois coal
plant I worked with whose electrostatic precipitator
(ESP) was designed for coal with
a sulfur content of 1.5% or greater. Knowing
that eventually they would need to begin
burning low-sulfur PRB coal, plant management
undertook a major upgrade to their ESP
that included sealing leaks in the ductwork
and casing, upgrading the transformer-rectifier
sets, and installing an improved rapping
and spark control system. Years before
the first PRB coal train arrived at the plant's
gates, it had switched to a higher-moisture
and higher-ash local coal that ordinarily
would have led to derates resulting from both
opacity and induced draft fan capacity. However,
the upgraded ESP allowed the plant to
meet the utility's load-demand requirements
and stay high on the dispatch curve.
Another utility I worked for had an ancient
coal power plant that it had decided to keep
alive for the next 20 years via capital improvements,
and the plant managers came to me
with a question: " Given that our existing coal
diet is very limited, and given these capital upgrades
that we can make to improve fuel flexibility,
which upgrades will give us the best
return on our investment? "
To perform this analysis, we obtained
operating cost data from the power plant, reviewed
its capital expenditure plan, and examined
its current short-term and spot coal
market situation in the region. Being located
directly in the Appalachian region, there were
approximately 300 viable sources for truck
2. Risk management. Some plant fuel
flexibility upgrade options make clear sense in
this case, such as repairing duct leakage and
bringing sootblowers back into service. Other
options, such as sulfur injection, are clearly
high-risk upgrades. Note that in some cases,
although the mean payback period may be
higher than for another upgrade option, the
risk of performing the upgrade is less (namely,
bringing preheat coils back into service versus
upgrading the electrostatic precipitator transformer-rectifier
sets and rapping controls).
Courtesy: Black & Veatch
and train-delivered coal, which we reduced
to a " best 60 " group for consideration. We
then performed a 10-year analysis using the
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11518 Old La Porte Road
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Phone +1 713 567 2700
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POWER September 2015

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