POWER April 2017 - 43

OPERATIONS & MAINTENANCE
1. Variable output. Each of Duke Energy's 34 operational coal-fired units are color coded
in this chart showing generation produced during a 16-month period between 2015 and 2016.
Courtesy: Duke Energy
Month
2. Unit starts. This chart shows the number of starts each unit performed in 2016. Courtesy:
Duke Energy
and modeling fuels, blends, and firing strategies
to predict the impacts on corrosion rates (mils/
year tube wall loss) at a given stoichiometry.
Fuel flexibility, combustion performance,
heat transfer changes from fuels, and flue gas
volume also affect nearly all environmental
controls equipment, demanding attention to
detail, along with intelligent process equipment
and optimization controls. This is especially
true for the units faced with load cycling,
fuel quality variation, and stringent environmental
regulations. Ideally, the analysis of
boiler performance (efficiency and reliability)
should have adequate key performance indicators
to detect alarms and provide the needed
intelligence to change operational conditions
and mitigate events before they occur.
Whether it is real-time, online, or offline,
practical and functional feedback from the
process instrumentation and plant equipment
assessments must be comprehensive, yet simplified,
to be productive. Operations require
the available feedback and knowledge base to
react when faced with operational challenges.
This is exacerbated with >40-year-old boilers
competing with more efficient combined
cycle gas units-and their responsiveness to
the changing dispatch curves-and renewable
power generation. Other variables that are essential
include the tools, equipment, and staff
required to collect representative samples for
periodic performance analysis.
Unit
3. Duke Energy's Combustion and Boiler Performance Program metric. Seven
different categories are assessed to identify areas ripe for improvement. Courtesy: Duke Energy
(1) Excess air control
(7) Training
(2) Mill-burner performance
(and condition)
Teamwork Is Essential
The first step is to define the measurement
process and then recognize the tools required
to identify and reduce gaps in performance.
Therefore, this requires both dynamic tools
and management processes that are grounded
on fundamentals and reliable measurements.
Nothing is more effective than a team of
professionals working together for a common
good. The joint effort initiatives through Duke
Energy's central services team are aimed at
supporting and strengthening the company's
capability to assess boiler components and
prioritize improvements needed for simultaneous
reliability, thermal efficiency, and environmental
performance improvements.
The incentives for implementation of a com(6)
Fuels prep
(3) Boiler heat transfer
optimization
(5) Air-gas flow
timately, the expected useful life of boiler
components. Much like a doctor practicing
medicine, technology, instruments, and health
assessments can be deployed to help ensure that
boilers continue to age gracefully in an effort
to mitigate unexpected life-threatening events.
April 2017 | POWER
(4) Combustion byproducts
Fuel properties also significantly influence
performance and emissions. Trending and understanding
the fuel-related effects on boiler
performance and components are imperative for
high efficiency, dispatch optimization, and reliability.
This can be accomplished by monitoring
www.powermag.com
prehensive program are easily justifiable in fuel
cost, heat rate, and overall operating performance
that includes generation, startup fuels,
environmental implications, and additional operations
and maintenance costs that are related
to forced outages. Figure 3 offers an example
metric used by Duke Energy to benchmark individual
station performance (Table 1) in order
to identify areas for improvement so that the
highest standards can be achieved.
Beyond Benchmarking
Going beyond best practices, but not to be
43
Number of starts
Generation (MWh)

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POWER April 2017

Table of Contents for the Digital Edition of POWER April 2017