POWER October 2010 - 48

TOP PLANTS
Tolk Station, Earth, Texas
Owner/operator: Xcel Energy
Located in a semi-arid region, this " Texas tough " coal-fired power plant uses a
number of smart practices to increase water-use efficiency. For example, a pipeline
was constructed to send blowdown water from nearby Plant X for treatment
and recycling at the 1,080-MW Tolk Station, making both plants " zero-discharge "
facilities. For its environmental stewardship and superior plant operations, the
Powder River Coal Users' Group named Tolk Station its 2010 Plant of the Year.
By Angela Neville, JD
W
ith a backdrop that looks like the set
of the Lonesome Dove television
miniseries, Tolk Station delivers
power not only to Xcel Energy customers in
Texas and New Mexico but also to customers
of rural cooperatives and municipal utilities
in the region. The facility is situated on the
western edge of the Texas Panhandle, which
is traditional ranching country. Specifically,
the plant is located near what was once the
XIT Ranch, which, when it was one of the
largest ranches in U.S. history, covered more
than 3 million acres.
Plant Profile
Tolk Station was designed in-house in the late
1970s by the generation plant design group
at Southwestern Public Service Co. (Xcel
Energy's Texas-based operating company).
Total construction cost was $571 million, or
$506/kW (about half the national average),
according to David Low, Tolk and Plant X
plant director. A single general mechanical
contractor was used, along with four subcontractors.
The plant was designed to burn
Powder River Basin (PRB) coal.
" The plant was designed for low station
loads by using variable-frequency drive fans,
two-speed main circulating pumps, and rifle
48
tubes on the waterwall, which reduced horsepower
requirements from boiler circulating
pumps, " Low said. " The units had the first
submerged scraper conveyor design in the
U.S. The Unit 1 and Unit 2 cooling towers, as
well as the Unit 2 baghouses, were in-house
designs. The plant layout was designed for
ease of maintenance due to fact that the design
group had visited with plant personnel. "
Other features include a separate economizer
ash collection system, economizer in-line
tubing to ease cleaning, a rotary dumper building,
an Amertap system to keep the condenser
clean, twin 4,160 V start-up boiler feedpump
motors (not 6,900 V switchgear), cooling tower
riser valves, an auxiliary circulating water plate
heat exchanger, air preheater sector seals, and a
control room simulator for training.
Each of the plant's two units, completed in
1982 and 1985, has a generating capacity of
540 MW. Tolk Station is the largest generating
plant in the Texas Panhandle-Plains region.
Low described the following operations of
the plant:
■ Overall efficiency rate: Unit 1-530 MW
net, 9,574 Btu/kWh (tested in 2009); Unit
2-535 MW net, 9,870 Btu/kWh (tested
in 2008).
www.powermag.com
Courtesy: Xcel Energy
■ Forced outage rate: 2.75% for 2009.
■ The equivalent forced outage rate for the
past five years (2005 to 2009) ranged from
4.66% to 3.21%.
■ Equivalent availability factor during the
past five years ranged from 87.01% to
83.88%.
■ Gross capacity factor during the past five
years ranged from 76.18% to 82.17%.
■ Net capacity factor during the past five
years ranged from 75.32% to 81.74%.
Xcel has 106 employees at the facility handling
operation and maintenance duties. In
addition, Savage Companies provides coalhandling
services for the Tolk Station and
employs 26 workers at the facility. " We have
a very devoted crew that keeps the plant safe,
clean, and running efficiently, " Low said.
During the past decade, the Savage Companies
have carried out the following capital
improvement projects at the facility:
■ New fire suppression systems for mobile
equipment: 2006
■ Controls upgrade: 2006
■ Replacement baghouses: 2005
■ Replacement fire suppression system: 2005
■ Railcar dumper refurbishment: 2002 to 2005
POWER | October 2010
http://www.powermag.com
POWER October 2010

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