Steam turbine vs Gas turbine – Difference (Explained)

The key difference between the steam turbine vs gas turbine is that the gas turbine converts the chemical energy of the fuel into mechanical energy and the steam turbine converts the high-pressure energy of the steam into mechanical energy.

Let’s take a brief look at the steam turbine and gas turbine before we get to our main question.

Steam turbine:

steam turbine image

The steam turbine is a rotating device that converts the energy of the steam (by virtue of high pressure and temperature) into the mechanical work output at the rotor shaft. The steam turbine is used in most power plants for electricity generation in which the electrical generator is coupled with the turbine output shaft.

The turbine is consist of a ring of nozzles and ring of fixed blades mounted on the casing and a ring of moving blades mounted on the rotor shaft.

The high-pressure steam is passed through the set of fixed blades, nozzles, and moving blades which causes the turbine shaft to rotate.

Other than power generation, the turbine is also used to power different types of equipment and locomotives.

Gas turbine:

The gas turbine is one of the internal combustion engines that work on a Brayton cycle and uses air as a working fluid to rotate the turbine. It converts the chemical energy of the fuel into mechanical energy at the rotor shaft.

The gas turbine mainly consists of the components like the compressor, combustion chamber, and turbine.

gas turbine image

As shown in the above figure, the air from the atmosphere enters the compressor where it gets compressed and sent into the combustion chamber.

The combustion chamber adds fuel to the compressed air and ignites the air-fuel mixture. The combustion of the mixture increases its kinetic energy and temperature.

Now, these high-temperature gases are expanded into the turbine to rotate the rotor shaft.

The gas turbine uses less floor area for mounting and also has less running cost but one of its main disadvantages is that it has lower thermal efficiency.

The gas turbine is used in many applications including power generators, aircraft, trains, etc.

Difference between gas turbine and steam turbine:

Sr. No.Gas turbineSteam turbine
1The gas turbine converts the chemical energy of the fuel into mechanical energy.The steam turbine converts the high pressure of the steam into mechanical energy.
2The operation of the gas turbine is based on the Brayton cycle.The operation of the steam turbine along with other components is based on the Rankine cycle.
3The gas turbine uses the air as a working fluid.The steam turbine uses steam as a working fluid.
4It comprises a turbine, compressor, and combustion chamber in a single unit.A steam turbine is a separate unit and it needs to be connected to the steam generator, condenser, etc.
5The working temperature of the gas turbine is higher than the steam turbine.The temperature of the steam turbine is less than the gas turbine.
6The starting of the gas turbine is easier.The steam turbine takes time for starting its operation.
7The gas turbine consists of the compressor, combustion chamber, turbine, etc.The steam turbine consists of rings of fixed blades, rings of moving blades, nozzle ring, etc.
8The water is not necessary for the operation of the gas turbine.It requires an adequate amount of water for its operation.
9It has lower thermal efficiency.It has higher thermal efficiency.
10The gas turbine can fit within a less floor area.The power generation by use of steam turbine requires more space for installing different units like boiler, condensers, turbine, etc.
11It is used in aircraft, trains, power plants, etc.It is used for electricity generation as well as to power different devices, and locomotives.
12The installation cost for the gas turbine is lower than the steam turbine power plant.The installation cost of the steam turbine power plant is higher.
13It never reuses the working fluid.It uses the working fluid again by use of a condenser.
14The running cost is less for the gas turbine. The running cost is higher for the steam turbine.
The table shows the comparison between gas turbine and steam turbine.

FAQs:

  1. Which is more efficient gas turbine or steam turbine?

    The steam turbine is more efficient than the gas turbine.

  2. What is a disadvantage of a gas turbine compared to a steam turbine?

    The disadvantage of the gas turbine compared to a steam turbine is that the gas turbine has low thermal efficiency.

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