1. Fuel Preparation:
- Natural gas is first treated and compressed to increase its pressure.
- Impurities like sulfur and water vapor are removed to prevent damage to the power plant's equipment.
2. Combustion:
- The cleaned natural gas is mixed with air and burned in a combustion chamber.
- This combustion process generates high-pressure hot gases.
3. Gas Turbine:
- The hot gases from the combustion chamber are directed to drive a gas turbine.
- The turbine's blades rotate due to the force of the expanding gases, generating mechanical energy.
4. Generator:
- The rotating gas turbine is connected to an electricity generator.
- As the turbine spins, it rotates the generator's rotor, which is surrounded by stator windings.
- This relative motion induces a flow of electrons in the stator windings, producing alternating current (AC) electricity.
5. Heat Recovery Steam Generator (HRSG):
- After exiting the gas turbine, the hot exhaust gases still contain significant heat energy.
- These hot gases pass through a heat recovery steam generator (HRSG).
- The heat from the exhaust gases is used to generate steam.
6. Steam Turbine:
- The high-pressure steam generated in the HRSG is directed to a steam turbine.
- As the steam expands and passes through the turbine blades, it causes them to rotate.
- The mechanical energy from the rotating turbine is then used to drive another electricity generator.
7. Condenser:
- After passing through the steam turbine, the steam is condensed back into water in a condenser.
- Cooling water is circulated around the condenser to absorb the heat and convert the steam to liquid form.
8. Cooling Tower:
- The cooling water used in the condenser is heated during the condensation process.
- This warm water is sent to a cooling tower, where it is cooled down and recirculated for reuse.
9. Electrical Distribution:
- The electricity generated from both the gas turbine generator and the steam turbine generator is synchronized and sent to a power substation.
- The substation increases the voltage of the electricity for efficient transmission over long distances through power lines.
- From the substation, the electricity is distributed to homes, businesses, and other consumers.
By utilizing both gas turbine and steam turbine cycles, combined cycle power plants achieve higher overall efficiencies in converting natural gas into electricity compared to conventional power plants. This process results in reduced fuel consumption and lower carbon emissions per unit of electricity generated.
