GAS TURBINES

Introduction:-

The gas turbine is the engine at the heart of the power plant that produces electric current.A gas turbine is a combustion engine that can convert
natural gas or other liquid fuels to mechanical energy. This energy then drives a generator that produces electrical energy. It is electrical energy that moves along power lines to homes and businesses.

HOW GAS TURBINE POWER PLANTS WORK:-

The combustion (gas) turbines being installed in many of today's natural-gas-fueled power plants are complex machines, but they basically involve three main sections:

• The compressor, which draws air into the engine, pressurizes it, and feeds it to the combustion chamber at speeds of hundreds of miles per hour.
• The combustion system, typically made up of a ring of fuel injectors that inject a steady stream of fuel into combustion chambers where it mixes with the air. The mixture is burned at temperatures of more than 2000 degrees F. The combustion produces a high temperature, high pressure gas stream that enters and expands through the turbine section.
• The turbine is an intricate array of alternate stationary and rotating aerofoil-section blades. As hot combustion gas expands through the turbine, it spins the rotating blades. The rotating blades perform a dual function: they drive the compressor to draw more pressurized air into the combustion section, and they spin a generator to produce electricity.

To generate electricity, the gas turbine heats a mixture of air and fuel at very high temperatures, causing the turbine blades to spin. The spinning turbine drives a generator that converts the energy into electricity.

The gas turbine can be used in combination with a steam turbine—in a combined-cycle power plant—to create power extremely efficiently.

1. Air-fuel mixture ignites.
   • The gas turbine compresses air and mixes it with fuel that is then burned at extremely high temperatures, creating a hot gas.
2. Hot gas spins turbine blades.
   • The hot air-and-fuel mixture moves through blades in the turbine, causing them to spin quickly.
3. Spinning blades turn the drive shaft.
   • The fast-spinning turbine blades rotate the turbine drive shaft.
4. Turbine rotation powers the generator.
   • The spinning turbine is connected to the rod in a generator that turns a large magnet surrounded by coils of copper wire.
5. Generator magnet causes electrons to move and creates electricity.
   • The fast-revolving generator magnet creates a powerful magnetic field that lines up the electrons around the copper coils and causes them to move.
   • The movement of these electrons through a wire is electricity.