Thermal Power Plant
Combined Cycle Power Plants
INNER WORKINGS OF A COMBINED-CYCLE POWER PLANT
A combined-cycle power plant uses both a gas and a steam turbine together to produce up to 50 percent more electricity from the same fuel than a traditional simple-cycle plant.
The waste heat from the gas turbine is routed to the nearby steam turbine, which generates extra power.
HOW A COMBINED-CYCLE POWER PLANT PRODUCES ELECTRICITY
This is how a combined-cycle plant works to produce electricity and captures waste heat from the gas turbine to increase efficiency and electrical output.
1- Gas turbine burns fuel.
• The gas turbine compresses air and mixes it with fuel that is heated to a very high temperature. The hot air-fuel mixture moves through the gas turbine blades, making them spin.
• The fast-spinning turbine drives a generator that converts a portion of the spinning energy into electricity.
2- Heat recovery system captures exhaust.
• A Heat Recovery Steam Generator (HRSG) captures exhaust heat from the gas turbine that would otherwise escape through the exhaust stack.
• The HRSG creates steam from the gas turbine exhaust heat and delivers it to the steam turbine.
3- Steam turbine delivers additional electricity.
• The steam turbine sends its energy to the generator drive shaft, where it is converted into additional electricity.
Simple‐Cycle Power Plants
High-efficiency, versatile solutions for limited space situations
A smaller footprint physical plant doesnft mean settling for less output
Simple cycle power plants provide a flexible and reliable power generation solution. Simple cycle power plants consist of a gas turbine that is connected to an electrical generator. Modern gas turbines are high-technology packages comprising a gas compressor, fuel combustors and a gas expansion turbine (power turbine). In the gas turbine, air is compressed in the gas compressor.
Energy is added to the compressed air by burning liquid or gaseous fuel in the combustor. The hot, compressed air is expanded through a gas turbine, which drives both the compressor and an electric power generator.
Although simple cycle is less efficient than combined cycle, the plant is quicker and cheaper to build and has certain operational advantages. One key advantage of the gas-fired simple cycle plant is its operational flexibility. It can be started up quickly, bringing electricity on-line whenever it is needed. That’s why simple cycle power plants are often used to provide peak load or standby service.