POWER November 2020 - 21

RESEARCH & DEVELOPMENT
(EFOR). Up to 68% of the current fleet,
or 751 boilers, are in this subcritical category,
and the EFOR rate increases with
age. For example, a 100-MW coal plant
can expect to see its EFOR rate go up to
about 17 outages a year after it has been
in operation for 40 years.
Embracing the latest computer technologies
can also aid the development
of advanced materials. For example, a
NETL study demonstrated that machine
learning (ML) and data analytics can be
used in designing next-generation alloys
to operate fossil fuel plants with greater
efficiency
while producing
affordable
electricity and lowering greenhouse gas
emissions. Researchers at NETL's Albany,
Oregon, facility validated the application
of ML analysis to enable more rapid
and accurate design of high-entropy alloys
(HEAs), critical materials for ultraefficient
power generation.
HEAs are alloys constructed with equal
or nearly equal quantities of five or more
metals, combining the strength and characteristics
of the individual elements into
a superior substance. Unlike conventional
alloys, HEAs possess special properties,
including outstanding wear resistance,
exceptional high-temperature strength,
structural stability, and superb corrosion
and oxidation resistance, all characteristics
needed to achieve maximum benefits
in advanced power stations.
For instance, boilers and other components
made from HEAs will enable power
plants to burn less fuel and operate with
greater efficiency at increased temperature
and pressure levels. HEA components
also are better equipped to withstand the
stresses of frequent power plant startups
and shutdowns required for integration of
renewable energy sources into the grid.
NETL's use of ML technology also eliminated
the trial-and-error method to develop
these advanced materials, speeding
up development time while minimizing
costs and expenditure of resources, making
it much more feasible to deploy these
alloys inside power plants.
Monitoring for Longevity
The DOE Office of Fossil Energy (FE) has
supported more than 50 NETL-led R&D
projects on cost-effective technologies expected
to bring about near-term benefits
for incorporation into commercial fossil
plants. The projects are sponsored primarily
by FE's Transformational Power Generation
program and the High-Performance
Materials program, but also several other
programs, and typically include project
teams with academia and industry. These
November 2020 | POWER
range from bench-scale testing to validation
testing in actual fossil power plants.
The Transformative Power Generation
program develops technologies to
improve performance and extend the
life of existing power plants. Program research
also focuses on next-generation
modular coal-fired power plants providing
stable power generation with operational
flexibility and high efficiency, as well as
oxy-combustion and chemical looping
combustion-technologies that provide
options for coal-fired power generation in
a carbon-constrained future.
Innovative technologies being researched
include online sensors, instrumentation,
algorithms, and failure mode
detection systems to monitor key plant
components and inform possible repairs.
One such concept is condition-based
monitoring, a maintenance philosophy
that actively monitors the condition of
equipment to predict failures and schedule
maintenance to maximize availability
and generating capacity while saving cost.
R&D is also being performed on tools for
predicting the life of critical equipment to
ensure long-term safety and reliability of
existing plants. For example, data analytics
for coal plants for continuous controller
characterization can grant operators
optimized facility control, improved efficiency
and economics, and improved control
during load following, while detecting
equipment deterioration so it can be addressed
before costs mount.
Technology development efforts are focusing
on rapid cycling and methods for
responding to load changes. Advanced
control methods for monitoring coal pulverizer
operation, and controlling steam
and gas temperatures at low loads are
being field-tested to improve the performance
and economics of existing power
plants. The implementation of neural networks
and sensor technologies enables
intelligent control for optimal combustion
system performance and can improve
flexible operation capability.
Improving plant efficiency is critical
to the economic viability of coal-fired
power plants. Enhancements to steam
cycle efficiency involve additional steam
generation, pump and cooling tower upgrades,
and advanced ultrasupercritical
retrofit options that include increased
steam temperature and use of advanced
materials for enhanced heat transfer efficiency.
Efficiently recycling resources,
such as waste heat and water, also presents
advantages for increasing plant efficiency
and reducing costs.
Power plant testing of these technolowww.powermag.com
gies
is focused on operating commercial
plants and includes 21 different plants
owned by 24 utilities in 12 states spanning
the continental U.S. and Hawaii.
Testing units range in size from 135 MW
to 952 MW and include a range of coals:
bituminous, subbituminous, and lignite.
Boiler types include cyclone-fired,
opposed-fired, and tangential-fired configurations,
and span subcritical, supercritical,
and ultrasupercritical boilers.
By developing the right tools and techniques
alongside its
partners, NETL is
working toward a proactive approach in the
day-to-day operations of the fleet. The discoveries
made along the way, combined
with changing energy trends, could also
lay the groundwork for how power plants
of the future are designed and built.
Perks of Partnering with NETL
NETL is uniquely positioned to bring new
life and capital investment into this critical
facet of the nation's infrastructure and security,
thereby sustaining local jobs and communities.
This is due to the lab's ability to
engage in research that might be cost-prohibitive
for industry to tackle alone, all while
partnering with the private sector, universities,
and other government agencies including
other DOE national laboratories.
This ability to work cooperatively also
helps members of industry who are front
and center at plant operations. They can
approach the lab with the problems they
need addressed, allowing for a bottom-up
process of research and problem-solving,
rather than a top-down approach. By licensing
its innovations, NETL is also committed
to ensuring tools and techniques developed
in-house make into the hands of those who
will make the most use of them.
" Ultimately, our work at NETL is all
about adapting with the times, and we do
that by exercising our analytical capabilities
and by listening to stakeholders. If need be,
we adjust our program plans and activities
accordingly, " White said. " We are always
looking for project partners. If you are a utility,
we want your input on what challenges
you are seeing in the field. If you are a technology
developer, we want to know what
opportunities you are seeing in the market.
By combining our experiences and expertise,
we can find solutions that lower costs
while improving performance and reducing
environmental footprints. We can have the
best of all worlds. " ■
-Briggs White is a technology manager
for High Performance Materials, and
Conor Griffith is a technical writer at the
U.S. Department of Energy's National
Energy Technology Laboratory.
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POWER November 2020

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