What is steam turbine and its types?

A steam turbine is a machine that converts the heat energy contained in compressed steam into mechanical work, which is often used to generate electricity or move tools. Steam engines are used in a variety of applications, including power plants, factories, and ships, due to their efficiency and ability to generate a large amount of power.

Steam turbine working diagram with types like impulse turbine and reaction turbine

Principles of a Steam Turbine:

The Rankine Cycle is the core concept behind how steam engines work. It consists of the following steps:

1). Steam Generation: To produce high-pressure steam, water must be heated in a boiler or heat exchanger. Steam is compressed to get the most energy from it.

2). Steam Expansion: In a turbine, high-pressure steam is sent to the rotor's blades or vanes. As the steam runs over the blades, it expands and loses pressure, causing the rotor to spin.

3). Work Output: The rotating rotor is powered by an engine, mechanical force, or other means to move forward. As the rotor spins, it does mechanical work, generates electricity, or propels a ship or other machine.

4). Steam Exhaust: After passing through the engine, low-pressure steam is sent into a condenser, where it is converted back into water. The condensed water is then sent back to the boiler to be heated and converted back into steam. This completes the cycle.

Types of steam turbines:

Steam engines are classified according to their shape, method of operation, and location of use. These are the main types of steam turbines:

Impulse Turbine
Reaction Turbine
Combined impulse and reaction turbine (compound turbine)

1) Impulse Turbine:

Impulse turbine showing high-velocity jets striking blades to produce rotation

In an impulse turbine, high-pressure steam is spread out across a set of fixed needles or blades (known as a rotor) to convert the steam's kinetic energy into mechanical work. Typically, a number of high-speed steam jets power the rotor, which is made up of a series of spinning blades. Impulse turbines are often used for smaller tasks or when high spinning speeds are required.

2) Reaction Turbine:

Reaction turbine showing fixed and moving blades converting steam pressure into rotational energy

In a reaction turbine, steam expands as it passes between a set of still and moving blades. As the steam travels through the blades, its pressure and speed decrease. The pressure difference between the input and exit is used to power the turbine. Reaction turbines are more often used in large power plants due to their efficiency and ability to handle a wide range of flow and pressure conditions.

3). Combined impulse and reaction turbine (compound turbine):

Diagram of a compound turbine showing impulse stage followed by reaction stage for efficient energy conversion

In stages, this kind of turbine employs both the impulse and response concepts. High-Pressure Steam Passes Through a Series of Impulse Stages To Reduce Pressure and Speed. It then goes through a series of reaction stages to extract more energy from the steam. Compound turbines are often used for medium-sized jobs and are designed to be as efficient as possible.

How Do Steam Turbines Work?

Diagram showing steam entering turbine blades, rotating the shaft, and generating mechanical power

A Steam Turbine Generator works by heating water to very high temperatures till it turns into steam. The steam is then used to turn the blades of a turbine, generating mechanical or spinning energy. The spinning energy is used to generate power via a generator connected to the steam engine. Here's a simple, step-by-step guide:

Heat energy is generated by some kind of heat source, such as burning solid fuel or the sun.

The heat energy from the boiler converts the water within the boiler into high-pressure steam.

The image above depicts the next step in the process of making a steam engine.

If the device uses a solid fuel that may be burned for heat, it requires an exhaust pipe to remove the pollution. If the system converts heat using solar energy, an outflow pipe is not required since the solar energy system emits no pollution.

The water in the boiler is heated to produce steam, which is then sent to the steam engine. Steam turns the rotor's blades.

A moving shaft connects the engine with the steam turbine. As the steam engine turns, the generator generates energy.

A cooling tower is used to cool the steam that propels the engine and provides power. A lake or river would be a natural way to release the steam.

The Cooling Tower releases low-energy, cooled steam into the atmosphere. The remaining water that has turned back into liquid is pumped back into the boiler, where the process begins again to generate more energy from steam.

Advantages:

High productivity: Steam engines are well-known for how efficiently they use heat. They are capable of converting a significant portion of the heat energy in steam into mechanical work. Steam turbines are highly efficient and versatile, making them suitable for a variety of applications ranging from small industrial processes to large power plants.

Fuel Flexibility: Coal, natural gas, biofuel, and nuclear fuel may all be used to power steam turbines. This makes them adaptable to many energy sources and allows them to switch fuels as needed.

Steam engines have a high output power, thus they may be used to provide baseload power, which is critical for keeping electricity lines safe.

Environmental Benefits: Steam engines may be configured to use technologies such as combined heat and power (CHP) or co-generation, which use waste heat for heating or other purposes. This improves energy efficiency in general and reduces greenhouse gas pollution.

Dis-advantages:

High Initial Cost: Making, installing, and maintaining steam engines may be costly. A Steam Engine System, which includes the generator and other tools, may need a significant initial investment.

Complicated Design: Steam turbines are complex tools that need meticulous craftsmanship. Because of the complexity of their components and systems, they need engineering experts to design, install, and maintain them.

Slow Start-Up and Turn-Off: When compared to other ways to generate electricity, steam engines take a long time to start and shut down. Steam engines may take a long time to reach full speed, making it difficult for them to respond quickly to changes in demand.

Repairs and Maintenance: Steam engines need regular maintenance to ensure that they function properly. Maintenance may be costly and need specialized tools and personnel.