Engines

GG4 and FT4

The Pratt & Whitney GG4 and FT4 are related aeroderivative gas turbine engines developed from the Pratt & Whitney J75/JT4 turbojet line. It is axial flow dual compressor turbojets with a can-annular type combustion element. It is typically operated as a turboshaft engine. In this configuration the gas generator provides the expanding gases to drive a power or "Free Turbine". This turbine is then used to drive electrical generators, mechanical pumps or for marine applications. The GG4 is a self contained, self regulating, remote operated, quick responding, peaking power generator. It is also used for propulsion in naval vessels and by water and gas pipelines to drive gas compressors. It was introduced in the 1960s with approximately 1300 units in operation at its peak. Many of these gas turbines are still in operation globally today.
The typical output of a single engine ranges from 16 to 30 MW depending on conditions and configuration. GG4 and FT4 gas turbine engines can be combined to work in conjunction with up to 8 other engines for more efficient power generation. They may also be operated as a combined cycle unit in combination with a condensate boiler in order to increase efficiency.