POWER October 2014 - 23

TOP PLANTS
1. Second career. Eskom's eight coal-fired units at the 1,600-MW Camden station were
first commissioned in 1967-1969. Following a period of excess capacity, all eight units were
mothballed in 1990. Fifteen years later, in March 2005, Unit 6 was revived to help Eskom increase
supply levels and potentially avert a power crisis, and all eight units were operating by
mid-2009. For scale, the stacks are 154 meters high and the cooling towers are 112 meters tall.
Courtesy: Eskom
was mothballed for two decades. For example,
air quality technologies have progressed and
acceptable emissions levels have decreased.
At Camden, each of the eight units was retrofitted
with fabric filters to reduce particulate
emissions. Eskom is also challenged by new
air quality regulations that begin to take effect
in 2015. Some of its existing plant sites
do not have sufficient water supplies to operate
new air quality control equipment, and
there is insufficient surplus system capacity
to span a necessary four- to five-month retrofit
outage without adversely affecting the
nation's electricity supply.
The return-to-service team also found it
first government-declared national electricity
emergency, on what has become known as
Black Friday, Jan. 25, 2008. Escalating power
demand forced Eskom in March 2014 and three
times in June to again declare a grid emergency
and implement load shedding when demand
rose to 36 GW during the evening peak period
for the first time since Black Friday.
Refurbished Power Plants
The Camden Power Station was the first
plant selected by Eskom for its return-toservice
program. Camden consists of eight
200-MW units with a design efficiency of approximately
33.4%. Original site work began
in November 1962. The first unit was commissioned
in April 1967, with the remaining
units commissioned through 1969. At the
time, Camden was the starting point of the
national power grid that used 400-kV lines to
interconnect the country.
Half of Camden's units were decommissioned
in 1988, and the remaining four units
followed in 1990 (also mothballed were the
Komati and Grootvlei coal-fired stations that
have also since been recommissioned). Camden's
Unit 6 was resynchronized in March
2005 and officially recommissioned that July,
followed by Units 7 and 8 in 2006; Units 3, 4,
and 5 in 2007; and Units 1 and 2 in 2008-all
at intervals of about six months. At 2146 hours
on Sunday, Apr. 19, 2009, Camden was operating
all eight units for the first time in 20 years,
adding 1,520 MW net to the Eskom grid. " Returning
these old power stations to service is
an important mitigation measure in our energy
security efforts, " South African President Jacob
Zuma said at Camden's recommissioning
ceremony on Oct. 23, 2010 (Figure 1).
Eskom's return-to-service program was
completed in 2014 with a total of 3,741 MW
October 2014 | POWER
at three recommissioned power plants now
supplying electricity to the national grid. In
spite of these additions to the grid, Eskom's
reserve margin still remains between 5% and
8%, which is insufficient to avoid periodic
load disruptions during weather events and
forced outages occurring during the peak usage
hours in the early evening.
In addition to the three return-to-service
plants, new coal-fired stations have been
commissioned and more are in the pipeline.
By 2017-18, Eskom will have added over 17
GW of new capacity since 2005 and expects
to double its installed capacity to 80 GW by
2030, in addition to adding 4,700 kilometers
(km) of new transmission network. Two
world-class power projects now under construction
are the 4,800-MW Medupi Power
Station, which consists of six supercritical
units and will be the biggest dry-cooled plant
in the world, and the 4,800-MW Kusile Power
Station, also with six units and the first
unit in South Africa with a flue gas desulfurization
system.
The cost to recommission the three plants,
according to Eskom, was $3.9 billion, with
$848 million spent at Camden. Eskom described
the Camden project at its recommissioning
as " the largest return to service
project in the world and has been successfully
reconstructed to add critical power capacity
onto the national grid at a fraction of the
cost of building a new facility. " According to
Eskom, the recommissioning project saved
almost $9.5 billion compared to the cost of
new power stations of equal size, and the
electricity was available much sooner.
Restart Challenges
As might be expected, there were many challenges
in resurrecting a coal-fired plant that
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difficult to procure important replacement
parts for equipment last made in the 1960s,
as most of the original manufacturers are no
longer in business. Reverse engineering of
many components was required in order to
source suitable parts. Finding and qualifying
operators and technicians was also a challenge.
Most new members of the plant staff
were hired from local residents as part of Eskom's
commitment to the community. Former
workers also returned to help return the
plant to service and to train new employees.
Eskom upgraded Camden's plant control
system with the latest Siemens Power and
Process Automation (SPPA) T3000 digital
control system. That project started in
February 2011 and will be completed by
the end of this year. The SPPA T3000 automates
the operation of each unit, including
turbine controls, boiler controls, and coordination
of other balance-of-plant equipment.
Perhaps the most important aspect of the
controls upgrades was the need to keep interruptions
in the operation of adjacent units
to a minimum when the upgrades were being
installed.
Camden requires 3 million to 3.4 million
tons of coal each year to operate. The minemouth
sources are now closed, so Camden
receives coal from mines located up to 16
km from the station. Trucking that much
coal is impractical, so Camden now receives
about 50% of its coal requirements by rail,
thereby reducing damage to the roads. The
short-term coal delivery solution was to
modify rail containers for road travel in
order to stockpile coal until a new rail facility
was constructed. " The rail migration
strategy will ensure cost-efficiencies, capability
of switching modes of transport from
the source of supply in the event of supply
challenges, minimise the social and environmental
impact, as well as improve safety on
the roads, " Eskom said. The new rail system,
once fully operational, will allow up to
four train deliveries per day. ■
-Dr. Robert Peltier, PE is POWER's
consulting editor.
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POWER October 2014

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