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Safely
to the Top
A final section of steel is
hoisted to the top of the boilerhouse in the GP3 project.
The topping off ceremony July 9 also marked one million
work hours without a lost-time accident.
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BY NORDAHL FLAKSTAD
Freelance Writer
The designers and builders of the Genesee Phase 3 Generating
Station are out to prove a thing or two. For one, they want
to help restore coal's reputation by tapping Alberta's abundant
reserves to produce power in an environmentally responsible
fashion.
For another, GP3's proponents aim to prove that engineering
and construction techniques originally developed in Japan
can swing comfortably into place in North America. EPCOR,
which sold a 50-per-cent interest in the $695-million GP3
to TransAlta Corporation earlier this year, has contracted
Hitachi Canada Ltd., a Japanese company.
When Hitachi and the other contractors and subcontractors
are done, a 450-megawatt, state-of-the-art plant will have
risen into cattle country's skyline, 75 kilometres southwest
of Edmonton - a plant that will meet or exceed Alberta's tough
new standards. It will, in fact, be the cleanest coal plant
in Canada.
Under a fixed, lump-sum contract, Hitachi (working with Jacobs
Engineering Group Inc. in Calgary) is providing engineering,
procurement and construction services to design and build
the high-efficiency, multi-stage, 256-tonne turbine generator,
as well as the supercritical boiler and related above-ground
facilities in the powerhouse.
Such an EPC role is new to Hitachi in Canada, although the
Japanese company is already an established supplier here of
turbine islands ¾ including turbine generators and
associated equipment ¾ to sites such as EPCOR's Clover
Bar station.
Familiar Names
For the two existing Genesee plants (GP1 and GP2, completed
in 1989 and 1994) EPCOR's permanent technical services contractor,
Colt Engineering Corporation, was the balance-of-plant contractor.
Colt has returned for GP3, and so has project manager Al Pettican,
P.Eng., who held the position for GP1 and GP2.
With Hitachi the EPC contractor for the power island and
boiler, Colt retains overall engineering responsibilities
for the balance-of-plant facilities ¾ including foundations,
the 138-metre stack, switch yards, bag house, electrical distribution
and human machine interface systems. Also, Colt has designed
interconnections with the existing units, which will share
some services with GP3, such as coal handling.
It's not only a technologically different project, this time
around. Adjacent GP1 was designed and constructed in more
than five and a half years. GP3, however, is scheduled for
completion in early 2005 - a mere three years after receiving
notice to proceed. It's already more than 50 per cent built.
Fast and Safe
"It's the tightest schedule of any project of this kind
in North America," notes Mr. Pettican. "We're the
only major (Alberta) project on schedule and on budget, and
with the best safety record."
In late June, GP3 marked one million work hours without a
lost-time injury. It's an impressive milestone, given the
hive of activity involving 42 contractors. By mid-summer,
1,000 construction workers were on site (in two shifts), and
the workforce is expected to peak at 1,100 this fall.
Not only is it safe, GP3 is also challenging. Alberta's first
major coal-fired power plant built in more than a decade must
demonstrate significant emissions reductions when stacked
against existing ones. That requires a number of strategies
and alternative technologies.
Incorporating a bag house instead of a precipitator, for
example, will ensure that only 10 parts per million of particulate
matter leave the stack. Importantly, fewer small, hard-to-trap
particulates of the so-called PM 2.5 type - particulate matter
up to 2.5 microns in diameter - will escape.
GP3 also reins in pollution by squeezing more kilowatts of
power from each 200 tonnes an hour of pulverized coal fed
into the boiler.
The result is a 10-per-cent CO2 reduction relative to GP1
and GP2, and 18 per cent less than the average Alberta coal-fired
generator. EPCOR has also undertaken to provide offsets ¾
based on emission reductions at other locations ¾ to
get the CO2 levels down to those of gas-fired generation.
Supercritical Returns
The Hitachi-designed Benson supercritical boiler will be
crucial in achieving EPCOR's goals.
Supercritical boilers were introduced to North America several
decades ago, only to be sidelined by their unreliability.
However, the technology persisted and was refined in Europe
and the Far East, and now the boilers are ready for a second
North American debut.
"This is the first modern supercritical boiler in North
America since the early 1970s," says Mr. Pettican, adding
that the move is prompting Americans to check out GP3.
The process relies on turning super-heated high-purity water
into steam - without the steam undergoing sudden expansion.
The high-temperature, high-pressure steam (3,500 p.s.i. at
turbine stop valves) turns the turbines while producing lower
energy loss when the steam is condensed.
That, says Mr. Pettican, means that compared with traditional
subcritical drum boilers (as in GP1 and GP2), supercritical
boilers "use less fuel, because they're more efficient.
Consequently they're less polluting because there is less
NO2, CO2, and sulphur per megawatt of production."
Complex Job
However, such operating advantages come at a cost in terms
of construction complexity. Notably, GP3 will require about
21,000, time-consuming welds, on site, to the vast array of
tubing racks that go into the supercritical boiler. If stretched
out, the tubes would extend some 311 kilometres.
Although some of these welds can be done at grade, many must
be done at elevation once parts of the boiler are hoisted
into place within the 73-metre-high structure. Hoarding must
be erected to protect the computer-controlled orbital welders
used by Alstom, a subcontractor.
The heavy lifting of large units required by Hitachi's construction
methods has meant that the frame housing the boiler has remained
fairly open during construction to allow the lifting of large
boiler modules. But now the building will be encased to facilitate
the welding, under controlled conditions.
Fortunately costs and inconvenience are being averted elsewhere.
Hitachi's design allows floors to be built completely on
the ground with the equipment slated for that floor. Using
frames, the whole, completed floor is lifted and nestled between
the four columns, then bolted into position.
The unusual design required some adaptation by Waiward Steel
Fabricators Ltd. of Edmonton, the principal steel fabricator.
Still, Mr. Pettican explains, "once they adopted it,
it made life a lot easier."
And he concludes: "Japan has fairly high labour costs.
By cutting the amount of labour on site, you can build it
faster and safer."
Related Article:
Careful Contract Packaging Keeps GP3 Costs in Line
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