Open Cycle & Closed Cycle Gas Turbines

Open Cycle & Closed Cycle Gas Turbines

OCGT

In an OCGT power plant the main components comprise the GT, generator and the associated auxiliary systems such as the fuel supply system, lube oil cooling system, fire protection system and the control system.

CCGT

In a CCGT power plant, the hot exhaust gases from the GT are delivered to a heat recovery steam generator (HRSG). The HRSG is a heat exchanger in which heat energy in the gases exhausted from the GT is transferred to water, which is then converted to steam. The mediumpressure high temperature steam generated in the HRSG is then delivered to a steam turbine (ST). In a CCGT plant, about two-thirds of the electrical power is derived from the GT and onethird from the ST.

The quality of the flue gas emitted from a GT in combined cycle mode is the same as from a GT in open cycle mode. However, the quantity of emissions for a notional level of output (CO2 per kWh) is greatly reduced owing to the improved efficiency of CCGT plant.