Bechtel Power Corporation

Bechtel Infrastructure and Power Corporation

Mark S Boulden

Seyfettin C Gülen

Ilya Yarinovsky

A combined cycle power generation plant has parallel normally-independent power generation trains, each having a gas turbine in line with a heat recovery steam generator. In a 'parked' or spinning reserve operational state, combustion is discontinued at the gas turbine of one power generation train, placed on turning fear. Combustion at the other power train is reduced, preferably to a minimum emissions-compliant level (NOx, CO) of the gas turbine operated at low level combustion. A bypass duct with controllable dampers apportions exhaust from the operating gas turbine to the heat recovery steam generators of both power trains. This maintains an elevated temperature in both heat recovery steam generators and enables fast restart.

Gas turbine combined cycle for high flexibility

A steam turbine driven electric power plant with an electric generator is switchable into an islanding mode wherein a main steam turbine is shut down and a lower capacity industrial steam turbine runs the electric generator instead, to supply house power to the plant while decoupled from the power grid. This avoids operating the main steam turbine and/or its steam source at reduced ratings for which they are not optimized and keeps the plant ready for restarting. The main steam turbine, the electric machine and the industrial steam turbine are mechanically engaged or disengaged through an SSS clutch, torque converter and transmission. In another mode, the electric generator is decoupled mechanically and operated as a mechanically unloaded synchronous motor coupled to the power grid, namely as a synchronous condenser wherein phased over- or under-excitation of the motor field windings supplies reactive power to the grid.

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Middletown, MD, United States of America

Mark S Boulden