POWER August 2010 - 28

2010 PLANT OF THE YEAR
2. The odd couple. Oak Grove's Unit 1 boiler was supplied by Combustion Engineering
(now Alstom Power) and the Unit 2 boiler, relocated from another project site, was supplied by
Babcock & Wilcox. Courtesy: Luminant, photo by Allison V. Smith
3. Patiently waiting. Construction first
began at the Twin Oaks project site in 1979.
Much of the boiler structural steel had been
erected and other plant below-ground infrastructure
completed when the project was
suspended. The site was later renamed Oak
Grove Plant when the project was restarted in
2005. Courtesy: Fluor
Table 2. Key Oak Grove performance parameters. Although the two supercritical
steam generators was supplied by different vendors, the performance specifications are essentially
identical. Source: Luminant/Fluor Power
Parameter
Net unit output
Turbine throttle conditions
Fuel
Emissions NOx
SO2
CO
PM10 (filterable)
Hg
Boiler
Type
Steam pressure
Steam temperature
Turbine
Unit 1 and Unit 2
796 MW
3,535 psig, 1,000F main steam
686 psig/1,000F reheat steam
Lignite from the Kosse Mine, 6,850 Btu/lb, 500 tons/hr (each unit),
12% ash, 33% moisture, 0.89% sulfur
0.08 lb/MMBtu
0.192 lb/MMBtu
0.34 lb/MMBtu
0.015 lb/MMBtu
Activated carbon injection, up to a rate of 9.2 lb/TBtu
Supercritical
3,721 psig
1,010F/1,005F
Maximum continuous rating 5,740,000 lb/hr
Rating
Type
870 MW
Single-flow high-pressure turbine, double-flow intermediate-pressure
(reheat) turbine, four-flow low-pressure condensing turbines
Rotational speed
Condenser vacuum
Feedwater heaters
Generator Voltage
Capacity
Boiler feed pump configuration
Water pretreatment system
3,600 rpm
2.26 inches HgA
Six stages of feedwater heating, including deaerator
24 kV
955 MVA @ 0.91 power factor
Two 50%-sized pumps, steam turbine-driven
Well water for service water and plant feedwater makeup
support of local communities, including the
cities of Franklin, Bremond, and Calvert.
The Twin Oaks plant morphed into the Oak
Grove plant because it was a " structurally advantaged
asset. " For example, the site construction
completed 30 years earlier included partial
erection of the Unit 1 boiler structure (Figure
3) and construction of the 2,330-acre cooling
28
lake (Twin Oaks Reservoir) with a completed
intake structure suitable for two plants. The
345-kV transmission switching station also
was partially completed and located within the
4,230-acre plant property boundary. Another
decided advantage of this site was its proximity
to the Luminant-owned Kosse Mine.
Located only about 15 miles away, the mine's
www.powermag.com
40,000-acre site has lignite reserves to fuel the
two-unit plant for more than 40 years.
A Two-Phase Plan
Fluor is Luminant's alliance contractor for plant
maintenance across the fleet. For more than 25
years, Fluor has provided ongoing engineering,
procurement, construction, and maintenance
services to Luminant and the former TXU
Power. During that time, Fluor employees have
worked more than 50 million hours across numerous
Luminant sites throughout Texas.
As part of that alliance, Fluor was years
ago tasked to properly preserve and maintain
the many plant components, including steam
turbines, generators, and boiler pressure
parts that had been procured years earlier.
That long-term relationship with Fluor was
fortuitous given that Fluor was later selected
as the engineering-procurement-construction
(EPC) contractor for Oak Grove (Table 3).
The first step for the Luminant-Fluor Oak
Grove team was to devise a plan to build the
two-unit plant starting with only a set of drawings
and specifications prepared prior to the
birth of many team members and using the plant
components in long-term storage. Luminant began
the process by contracting with the suppliers
of the turbines (GE), Unit 1 boiler (Alstom),
and Unit 2 boiler (B&W) to determine the work
required for reuse and later assigned these contracts
to Fluor as part of the EPC agreement.
Another constraint on the project design: Regardless
of when the parts were purchased, the
new plant had to meet modern plant codes, standards,
and air emissions regulations.
The team agreed on a two-phase contracting
approach. The first phase began with an
" open book " contract period of seven months
POWER | August 2010

http://www.powermag.com

POWER August 2010

Table of Contents for the Digital Edition of POWER August 2010