Terri-Jane Yuzda

All They Are Saying
is Give Coal a Chance

New technologies introduce generational change
at Genesee Power Plan

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.

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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