POWER September 2017 - 29

TOP PLANTS
1. GSU arrives onsite. The generator step-up unit arrived at the Paradise construction
site in March 2016. The plant would be put into commercial operation 13 months later, in April
2017. Courtesy: Tennessee Valley Authority
POWER POINTS
By the Numbers
2,472,019 - Number of man-hours
worked to complete construction.
6,187 - The net heat rate (BTU/
kWh) of the plant, making it the
most-efficient in TVA's fleet.
175 - Height in feet of the plant's
cooling towers, equivalent to an
18-story building.
11 - Minutes (or fewer) it takes
for the 7FA.05 gas turbines to
startup.
the project was completed 12 weeks ahead
of schedule and about 20% under budget.
There was about 18 months of upfront engineering
and procurement work for the project
in Lenexa, Kan., home base for Kiewit's
power group. " The success of the Paradise
project is entirely attributable to our project
team, " said Kiewit's Mike Wilkie, the project
manager. " Kiewit and its partners developed
a fully integrated, cohesive 'Paradise OneTeam'
defined by a spirit of collaboration in
which all team members worked together toward
a common goal. "
Construction Challenges
The goal was not reached without challenges.
" TVA began wrestling with a solution for the
Paradise Fossil Plant in 2012, " said Waldrep,
with the utility mulling options for its coalfired
units due to emissions regulations. " [We
were] considering additional environmental
controls for Units 1 and 2 at the coal plant,
or replacing the generation with a gas-fired
facility of either a four-unit simple cycle
configuration or a 3 x 1 combined cycle configuration.
TVA initially selected additional
environmental controls as the solution in
2012, but then reconsidered in 2013 as the
certainty of compliance became less and the
cost of ownership [of the coal plant] continued
to rise. "
The plant was completed ahead of schedule,
but the original end date was placed in
jeopardy at the beginning because of a sixweek
delay in issuance of the construction
air permit. The delay caused TVA and Kiewit
to compress the construction schedule in order
to meet deadlines set by the Mercury Air
Toxics Standards (MATS) rule, which said
the two coal units at Paradise could not legally
operate after mid-April 2017. Because the
new plant was replacing some of the generation
of the coal-fired plant, delays could imSeptember
2017 | POWER
pact TVA's ability to operate the transmission
system if there was a period without generation
in the region.
" This MATS date set an unofficial target for
the project, " said Waldrep. " Not only did the
project improve on the contractual completion
dates, it was able to meet the MATS date for
the coal units, helping TVA maintain the reliability
of the transmission system in the area. "
The Paradise plant is called the most-efficient
gas plant in TVA's fleet, and not just
for its electricity generation. Paradise Plant
Manager Drew Reid said, " The most-efficient
claim is based on the lowest heat rate
[net 6,187 BTU/kWh] in the TVA gas fleet,
as well as the innovative work management
efforts we have put in place. " Those include
sitewide Wi-Fi, a communication system for
the plant through iPads, and electric vehicles
to move around the complex, with charging
stations throughout. TVA also is using all
LED lighting to save energy and improve
visibility and safety.
Technical Specifications
The Paradise plant features three GE 7FA.05
combustion turbines, a dual flow-down exhaust
Toshiba steam turbine with 48-inch
last stage blades, three triple-pressure Vogt
HRSGs with reheat and supplemental firing,
a TEI double-pass deaerating steam surface
condenser, and a 16-cell induced-draft mechanical
cooling tower. The 16-cell tower
is a back-to-back design, with essentially
the same performance as a single-width 14cell
tower, according to Dan Langstraat, the
Kiewit Engineering Project Manager.
" The components are installed in a typical
wet-cooled, 3 x 1 combined cycle configuration, "
said Langstraat. " The Paradise pipe rack
uses tube steel columns in a moment-frame
design. Because of the tube shape, the loading
capacity of the steel is the same in both direcwww.powermag.com
tions.
This unique feature allowed the pipe
rack to be designed with zero cross braces, a
first for both Kiewit and TVA. To maximize
plant efficiency, the boiler feedwater pumps
furnished by KSB include variable-speed hydraulic
couplings designed and manufactured
by Voith. The couplings allow the pump to
'slip,' minimizing the brake horsepower consumed
by the pump at off-design cases. "
The water intake system also required
innovation. Langstraat said TVA wanted
to avoid a lengthy permitting process and
some of the challenges involved with working
around the river, so it opposed a traditional
onshore intake structure. The partners
worked out a technical solution, locating
a water intake structure inside the plant's
boundary fence. The system includes an
underground intake pipe routed to the river,
with a suction screen on the pipe beneath the
surface of the water.
" The intake structure was constructed of
a concrete caisson approximately 20 feet in
diameter that was sunk to a depth of nearly
70 feet, " said Langstraat. " The team then
used a micro-tunnel boring machine to drill
the intake pipe into the river where the suction
screen was placed. Locating the raw
water pumps and related equipment within
the plant boundary yielded two distinct advantages:
easy access for plant operators and
minimal river work during construction. "
Wilkie said Paradise, now the state's second
combined cycle plant in addition to the
Cane Run Generating Station in Louisville (a
2016 POWER Top Plant), could be a model
for TVA projects moving forward. " In the
end, the project was completed on time and
within budget in a way that formed the basis
of a lasting partnership " between Kiewit and
TVA, he said. ■
-Darrell Proctor is a POWER
associate editor.
29

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