Steam Turbine Working
The steam turbine is a type of engine turbomachine that modifies the energy coming from the steam flow in another kind of energy, mechanics. The turbines of this nature are often used in different power cycles employing a fluid having the property of changing phase.
The most used cycle is the one that uses steam coming from a boiler and that comes out with high temperature and pressure. Steam turbines are used to generate electrical energy from the mechanical energy it produces.
What is the use of a steam turbine?
Steam turbines are used in many circumstances because they are very versatile. At first, they behaved like the engines of ships that needed a lot of power. On the other hand, in industry, they are used for the operation of pumps and compressors. Even so, the most common and relevant application is to generate electric power.
It is estimated that the steam turbine is present in up to 75% of the electrical energy produced worldwide. It is used in thermal power plants (gas, coal, biomass, etc.) and in nuclear power plants.
How does steam turbine work?
- Steam is obtained from a boiler that boils water (the boiler is not part of the turbine structure). Oil, gas, coal or uranium can be used to heat the boiler.
- The steam that is produced has high pressure and high speed. To understand what it is about, you have to make the idea of a pot with a small hole through which steam comes out.
- Tubes, known as nozzles, carry the steam that is generated in the boiler to the turbine. When the steam reaches the turbine, it collides with some paddles by turning the turbine and the shaft it has.
- A row composed of pallets is called a reel, the turbine is made up of several reels that contain several pallets.
At this moment the chemical energy that comes from the fuel that was used to boil the water is being transformed into the energy of rotating movement or kinetic energy. If the rotor of the turbine is attached to a generator or dynamo, then electrical energy is produced.
What happens with the residual vapor?
When the steam comes out of the turbine spools, it has already lost strength and a certain degree of heat. However, this residual steam is used to convert it into liquid (condensation) and is directed back to the boiler. Then, it is reheated and reused in the circuit.
It is a closed circuit where the pressure and the residual heat of the value are used when it leaves the turbine. Losses are reduced by not letting it escape into the atmosphere.
Parts of the steam turbine
- Admission system: These are valves that control the steam flow at the inlet of the turbine. These valves are piloted hydraulically. In addition, they can be piloted by a group of control oil or pneumatically.
- Turbine body: It is composed of the rotor, which has the rotating crowns of the vanes or blades, the shaft, the stator, and the housing.
- Exhaust from the turbine: It is the back of the turbine and it is from where the steam goes to the condenser or back pressure pipe.
- Extraction or reinjection areas: Zone where the steam is extracted or injected.
- Vapor labyrinth closures: Reduces the leakage of steam through the holes.
- Reducer: When the speed at which the broken shaft is greater than that used to drive the alternator, the reducer is responsible for reducing the number of revolutions.
- Generator: Component that consumes the motor force emitted by the turbine and is responsible for generating electrical current.