Combined cycle leads efficiency race

Evidence of combined cycles` commercial success is everywhere and not just for peaking and small cogeneration purposes either. At 1,370 MW, Midland Cogeneration Venture has since 1990 operated one of the largest base-loaded independent power producer-owned plants in the United States. Using ABB power generation technology, the plant has set an hourly production record of 1,491 MWhr and a daily record of 34,842 MW and provides up to 1.35 million pounds per hour of process steam to nearby industrial users. More recently, Sithe/Independence Power Partners L.P. started commercial operation of its 1,020-MW (net ISO) combined-cycle cogeneration plant near Oswego, N.Y. The plant`s layout includes two GE multi-shaft combined-cycle systems that incorporate four 159-MW 7FA gas turbines, four Vogt heat recovery steam generators and two 209-MW GE steam turbines. Although the plant is primarily a baseload facility, it has been designed to handle up to 100 cold starts per year. According to GE, each combined-cycle block can reach full load conditions within five hours. Operational flexibility is further promoted via steam turbine bypasses that allow for simple-cycle operation without interrupting process steam to its industrial host. The topics of this article include: siting and permitting; steady efficiency gains; advanced turbine systemsmore » effort; and coal and the combined cycle.« less