August 15, 2006

Mountainview Power Plant, Redlands, California

Laszlo von Lazar, Bechtel Power Corp.

Project details

At the heart of Mountainview are two now-familiar power blocks, each powered by two General Electric (GE) 160-MW 7FA natural gas–fired, dry low-NOx (DLN) combustion turbines (CTs). The exhaust gases from each pair of CTs are fed to a supplementary-fired heat-recovery steam generator (HRSG) from Foster Wheeler Inc. (Clinton, N.J.) that, in turn, provides energy at 403,579 lb/hr and 1,055F to a GE D11 steam turbine-generator with a nominal rating of 210 MW. The HRSG duct burners are rated at 135 mmBtu/hr.

Selective catalytic reduction (SCR) with ammonia injection and CO catalytic reaction equipment reduce NOx and CO emissions from the plant: NOx to levels below 2.5 ppm on a 1-hour average and 2.0 ppm on an annual average basis, and CO to below 6 ppm on an hourly basis. The condenser was supplied by Alstom Power of France. The plant's overall heat rate is about 6,800 Btu/kWh (LHV).

Identifying available water supplies will only become more problematic for future plants in the region. Half of the water supply for Mountainview is treated reclaimed wastewater from the City of Redlands; the rest comes from new and existing wells on the site. The plant's water treatment equipment was supplied by Infilco Degremont Inc. (Richmond, Va.) and Aquatech International Corp. (Canonsburg, Pa.). Each 2 x 1 power block uses a wet, mechanical-draft Marley cooling tower from SPX Cooling Technologies (Overland Park, Kan.). The Bailey Controls division of ABB supplied the plant's distributed control system. Natural gas is delivered to Mountainview by Sempra's SoCal Gas Co. through a new, 17-mile pipeline.

Since going commercial, Mountainview has been dispatched as a 600-MW mid-peaker plant most mornings. At 2 p.m., the duct burners and evaporative coolers kick in, raising the plant's capacity to 1,000 MW and switching its mode to baseload. After 10 p.m., load returns to 600 MW, and at midnight the units are shut down. Mountainview was 100% available this June, the last full month of operation as this article went into production.