A gas turbine generator in simplest form harvests the power of expanding air to provide mechanical torque to spin a shaft. At the heart of the new flexible system design is a General Electric LM6000 turbine generator. Though modified to produce mechanical torque as opposed to thrust, the engine is the same that you would find on large jet aircraft.
The turbine is coupled to a Deltak Heat Recovery Steam Generator (HRSG) which uses the exhaust heat from the LM6000, and some additional gas firing, to produce steam to power a steam turbine generator, which already exists as part of the current plant.
The gas turbine can be run in simple cycle, with the HRSG, with an efficient operating range between approximately 21.5 and 43 megawatts. The gas turbine can be run in combined cycle, with the HRSG, to add approximately 22 megawatts of additional gas-produced electricity.
Purpose of the Compressor
Air is drawn into the low pressure compressor where it begins to build pressure by being forced into a smaller and smaller space. The high pressure compressor continues the process until the air has reached sufficient pressure. At this point, it enters the combustion chamber where fuel is burned. The resulting increase in temperature causes the air to expand rapidly. This expansion is the power source that drives the engine.
Purpose of the Turbine
The high pressure turbine uses the power from the expanding gas to spin the shaft connected to the high pressure compressor. The expanding air leaves the engine through the low pressure turbine. This power is transferred back to the front of the engine via a shaft to drive the low pressure compressor and the generator.
There are no physical connections between the low and high pressure sides of the turbine. Just like a fan slowly turning in the breeze on a summer's day, the force of the air turns the turbine blades.