POWER December 2014 - 47

heat rate improvement
information by operations staff: 75 Btu/
kWh to 100 Btu/kWh.
■ Optimize sootblower operation: 70 Btu/
kWh.
■ Initiate a routine testing program: 75 Btu/
kWh to 200 Btu/kWh.
■ Increase routine feedwater heater monitoring:
30 Btu/kWh to 60 Btu/kWh.
Boiler. Potential heat rate improvement
from recommendations to improve boiler
heat transfer and combustion were estimated
to be 100 Btu/kWh or better. Sootblowing
optimization was estimated to have a potential
improvement of 70 Btu/kWh.
Turbine. Potential heat rate improvement
from recommendations to improve turbine
cycle performance was estimated to be 100
Btu/kWh or better. Losses due to worn internal
seals and snout rings were estimated to be
20 to 50 Btu/kWh or higher.
Feedwater Heaters. Potential heat rate
improvement from replacing the first point
heater was estimated to be 150 Btu/kWh.
Plant heat rates were trended for onemonth
periods during the original PCO assessment
and then again during the follow-up
assessment. The time elapsed between the
original and follow-up assessments ranged
from 20 to 24 months. Heat rates were calculated
using two different methods: input/
output method and energy balance method.
Some plants reported expected heat rate
improvements from actions that they had
taken or planned to take, which ranged from
200 Btu/kWh to 400 Btu/kWh, approximately
2% to 4%. Though it was difficult to correlate
specific improvements with measured
data, it was clear from the assessments that
plant efficiency improved significantly at
four of the five plants completing follow-up
assessments. The magnitude of the heat rate
improvements ranged from 279 Btu/kWh to
557 Btu/kWh at or near full-load operation,
which represents an approximate 3% to 5%
improvement in heat rate. The results of this
project are site-specific and are not universally
applicable to all coal-fired power plants.
Winners and a Loser. Plant " A " improved
its heat rate by 279 Btu/kWh through comprehensive
organizational focus of multi-level heat
rate teams, training of operations staff, and close
attention to minimizing boiler excess air.
With a 557 Btu/kWh improvement, Plant
" B " decreased its heat rate by the largest
margin. This improvement was accomplished
through diligent cycle alignment, reduction
of boiler casing air in-leakage, a turbine
chemical cleaning, and reduced condenser
air in-leakage.
Plant " C " improved its heat rate by 400
Btu/kWh, of which plant staff attributed 100
Btu/kWh to boiler improvements and 250
December 2014 | POWER
Btu/kWh to steam path maintenance and a
feedwater heater replacement.
Plant " D " improved heat rate by 500 Btu/
kWh with substantial maintenance work, including
reducing boiler casing air in-leakage,
replacing a feedwater heater, and cleaning
condenser and feedwater tubes.
Unlike the other four plants in the followup
studies, heat rate for Plant " E " increased
unexpectedly by 350 Btu/kWh. This result
was thought to be due in part to increased cycling
and extended operation at lower loads.
Fuel Savings and CO2 Benefits. With
heat rate improvements ranging from 3% to
5%, the results of the PCO follow-up studies
clearly demonstrate that plant heat rate
can be favorably affected by operational and
cy Improvements (report 1019002). (See Part 1
in the November issue for more.)
The most powerful use of this approach
is to apply the method to an entire fleet, in
which a set of potential projects can be evaluated
for a group of specific coal-fired units.
In this project, the project team compiled a
list of feasible efficiency improvement options
and conducted analyses to determine
project-specific net annual benefits in relation
to reduction of CO2
emissions. Researchers
compiled information from various internal
sources and then added more projects from
an EPRI capital projects report. All projects
were listed in a spreadsheet and normalized
to match each unit within the current operating
system.
The numerical values presented in this article
may not be additive. They also may not
be achievable or justifiable at every coalfired
plant.
maintenance activities undertaken by plant
owners. Not all participants actively quantify
return on investment of activities in terms of
fuel savings, but these savings are very significant.
For example, a 5% improvement in
the heat rate of an 500-MW (net) power plant
can be worth more than $3,500,000 in annual
fuel savings and reduce CO2
180,000 tons annually.
emissions over
Fleetwide Assessment Case Study
In 2010, EPRI conducted a study with a
member utility to identify power plant efficiency
improvements that could be implemented
across all 12 coal-fired units in its
fleet to reduce CO2
emissions. The study and
its findings are described in the EPRI report
Methodology for Fleetwide Energy Efficiency
Analysis (report 1021206).
This project was undertaken to show how
coal plant energy-efficiency improvements
could be used to reduce CO2
emissions. The
utility established a Plant Energy Efficiency
Team (PEET) to explore the company's options
for improving coal plant efficiency.
The PEET results are focused on tons of CO2
avoided or reduced and the cost per ton of
CO2
per ton of CO2
avoided or reduced. The estimated cost
avoided or reduced for each
technology can be used to determine which
projects are potentially viable based on the
price of CO2
credits.
For the study, the project team applied a standardized
methodology previously developed for
evaluating efficiency improving projects in a
single power plant, described in the EPRI report
Capital and Maintenance Projects for Efficienwww.powermag.com
This
study covered only projects for existing
coal-fired power plants. This was not
an integrated resource plan study; the PEET
was not trying to determine how best to increase
generation. The assumption was made
that net plant output remained constant. If the
proposed project happened to increase capacity
along with efficiency, the fuel burn was
reduced to maintain a constant net output.
CO2
emissions reduced or avoided were then
calculated and summarized.
The following steps were used to evaluate
potential energy-efficiency improvement
projects for that fleet:
■ Assemble a team of experts within the
utility with collective knowledge covering
all of the units being investigated and all
the projects being considered.
■ Identify the potential projects, using the
spreadsheet in EPRI Report 1019002 as
the starting point.
■ Identify the coal-fired units to be included
in the analysis.
■ Screen projects for feasibility of application
to each unit in the fleet.
■ Determine project attributes for each application.
■
Evaluate the applicable projects for each
unit.
■ Develop project ranking based on the cost/
benefit analysis for each application.
■ Prepare Pareto curves to provide management
with a decision-making tool
to prepare for any future carbon-related
charges.
■ Issue fleet-specific report.
47
http://www.powermag.com
POWER December 2014

Table of Contents for the Digital Edition of POWER December 2014
