POWER August 2018 - 34

TOP PLANT
Clean Air Program Makes
Shawnee Power Plant a Winner
Courtesy: Tennessee Valley Authority
Emissions standards have changed a lot since the Shawnee Fossil Plant entered
service during President Eisenhower's second term in office, but the
Tennessee Valley Authority has done its part to help the facility meet all
current regulatory guidelines. A recent retrofit added selective catalytic
reduction and flue gas desulfurization to Units 1 and 4 at the plant. Space
made the projects challenging, but both were successfully implemented.
Aaron Larson
T
he Paducah, Kentucky, Convention and
Visitors Bureau website says, " Creativity
is the common thread that connects
people from around the globe to Paducah. "
There are few places around Paducah where
creativity has been more important than at
the Shawnee Fossil Plant located about 10
miles northwest of town. Space limitations
forced the Tennessee Valley Authority (TVA)
and its contractors to be creative in order to
install dry flue gas desulfurization (FGD) and
selective catalytic reduction (SCR) retrofits
on Units 1 and 4 at the facility.
The plant, which takes its name from the
Shawnee Indian tribe, has nine active generating
units with a summer net capacity of
1,206 MW. The station-commissioned in
1957-was originally built with 10 units;
however, Unit 10 was idled in 2010 and retired
in 2014.
Clean Air Program
TVA hired AECOM in 2015 to complete FGD
and SCR retrofits at Shawnee. The measure
was required as part of an agreement with
the U.S. Environmental Protection Agency,
as well as several states and environmental
advocacy groups, to reduce emissions from
Units 1 and 4 by December 2017. AECOM
performed the engineering, procurement,
34
construction, construction management, and
commissioning for the project.
Shawnee burns a blend of Eastern bituminous
and low-sulfur Powder River Basin
coals. The new FGD system was designed to
remove 96% of the SO2 produced in the combustion
process. Although the boilers were
previously equipped with low-NOx
burners,
additional reductions were mandated
by the clean air agreement. As a result, the
SCR systems-designed to remove 90% of
the nitrogen oxides produced in the combustion
process-were also required on Units 1
and 4. As an added benefit, the plant's Clean
Air Program reduced mercury emissions by
about 80% as well.
The FGD systems consist of spray dryer
absorbers (SDA) and associated subsystems,
such as hydrated lime storage and delivery,
byproduct recycling, and byproduct handling.
The SCR systems consist of reaction
vessels and auxiliary equipment as well as
an anhydrous ammonia storage and delivery
system (ATF).
Larry Nathan, TVA's project manager
for the job, told POWER that the public
corporation's Clean Air Projects group has
been installing scrubbers since 2004 at various
facilities including Paradise, Bull Run,
Kingston, and Gallatin, a 2017 POWER Top
www.powermag.com
Plant award winner (see " Improved Emission
Controls and State-of-the-Art Ash Handling
Extend Gallatin's Life " in the October 2017
issue). " Our team within TVA has worked together
for a long period of time and we've
learned a lot, so we utilize a lot of those people
from project to project, which adds to the
success, " Nathan said.
Several members from both groups had
worked on the Gallatin scrubber before transitioning
to the Shawnee retrofits. " We took our
lessons learned from that project and utilized
them on this project. We coordinated well with
each other and kept the plant abreast of work
that was going on, " said Nathan.
A Challenging Project
In an exclusive interview with POWER, Dennis
Pennline, power project manager with
AECOM Construction Services,
said
the
Shawnee project " was a very interesting job. "
He said one of the biggest challenges was
working within the available footprint for the
SCR and dry scrubber. Units 1 and 4 couldn't
be taken off-line for the two-year duration of
the project, so a temporary bypass had to be
installed on both units and then the SCR and
FGD had to be constructed around the ductwork.
" That was probably one of the biggest
challenges we had from a sequencing and
POWER | August 2018
http://www.powermag.com
POWER August 2018

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