New G4 technology on turbine compressor station

Implementing its new PGT25+G4 power turbine technology, GE Oil and Gas has completed an upgrade project for Alliance Pipeline that will provide greater power output, high efficiency and low emissions

Following the installation and successful startup of the first G4 unit, the Alliance Windfall Compressor Station in Whitecourt, of Alberta in Canada was returned to service in only three weeks.

The new module replaces an existing unit at the compressor station.

Introduced in late 2005, the G4 power module, which can be applied for both upgrade and new unit projects, is an upgrade of the GE well-proven PGT25+ technology and is specifically designed for oil and gas applications including large pipelines and onshore/offshore production facilities.

"Since the package design and the footprint are the same as for the previous PGT25+ unit, upgrading to the more powerful G4 can be done quickly and easily, reducing any downtime," said Jeff Nagel, vice president-global services for GE Oil and Gas: "This new upgrade technology enables our customers to grow without the cost and time involved in replacing an entire plant".

The GE Oil and Gas G4 turbine module is coupled with an enhanced GE LM2500+G4 gas generator to provide an output of 34 megawatts, a 10% increase over the previous model.

"This is a very exciting project for Alliance," said David Mucz, manager, technical services, Alliance Pipeline: "We are the first to use this new technology in this capacity, which keeps our system on the leading edge".

The two-stage turbine module is designed to achieve fuel efficiencies greater than 40%, the highest thermal efficiency level in its power range, while also offering low emissions of 25 ppmvd NOx and CO.

The first unit also features control software and hardware customised to meet the specific Alliance needs.

"We faced several challenges with our first G4 upgrade installation," said Nagel: "Alliance needed to maintain a low level of emissions while achieving a significant power increase along with high efficiency and availability.

The successful startup has demonstrated that our enhanced technology will meet these requirements".

Design features for the enhanced G4 include increases in firing temperature and axial compressor airflow.

Component innovations include a power turbine first-stage blade designed with the new GTD-111 directionally solidified alloy, and a new unit control panel and fuel metering skid designed for more accurate combustion tuning.

A dry low emissions (DLE) version is also available, as the one installed in Canada, for more precise combustion tuning.

Operating at a speed of 6100 rpm, the power turbine is capable of directly driving a compressor without the need of a gearbox in most oil and gas applications.

The gas generator for the new unit was manufactured by GE Aviation and delivered to the site at the end of March.

The power turbine and control panel were manufactured by GE Oil and Gas in Florence, Italy and delivered in May.

"The debut of our G4 technology builds on our relationship with Alliance, one of the world's leading pipeline companies," said Nagel: "GE has provided all of the compression equipment in the Alliance mainline pipeline system".

Based in Calgary, Alberta, the Alliance Pipeline system transports approximately 1.6 billion cubic feet of rich natural gas, from northeastern British Columbia and northwestern Alberta through Saskatchewan, North Dakota, Minnesota, and Iowa to its terminus in Illinois.

There are 14 compressor stations located across the 3,700-kilometer mainline system.

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