In 1791, John Barber created the first gas turbine. Thus, the majority of his design’s components could be found in the most recent turbines. These turbines operate at a higher temperature than steam turbines. Up to 60% is the gas turbine’s maximum efficiency. This turbine uses air as its medium of operation and runs on process gas, low-Btu coal gas, natural gas, and vaporized fuel oil gas as fuels. However, 90% of these turbines use liquefied natural gas or natural gas as their operating fuels worldwide.

What is a Gas Turbine?

A gas turbine is a combustion engine found in a power plant that converts natural gas or liquid fuels into mechanical energy. This converted energy is used to power an electric generator, which creates the electricity used by power lines to supply homes and businesses with electricity. In order to produce the electricity needed to turn the turbine blades, this turbine first heats a mixture of fuel and air to high temperatures.

In order to transform the energy into electricity, this rotating turbine powers an electric generator. Currently, pressurized gas can be created in modern gas turbines by burning fuels like kerosene, natural gas, jet fuel, or propane. Heat from the fuel can cause air to expand, allowing it to flow more freely through the turbine and produce useful energy.

Gas Turbine Construction

Compressor, shaft, combustion chamber, gearbox, and exhaust are the main parts of a gas turbine. The suction, compression, combustion, turbine, and electricity generation processes all play a role in how this turbine operates. The following describes the components of a gas turbine and how they work.

Suction

The air is transmitted to the compressor through the suction process, in which the turbine draws air from the atmosphere into the compression chamber.

Compression

As soon as air enters the compressor, it is reduced and the energy is converted from kinetic to pressure energy. The air is then transformed into high-pressure air by the energy.

Combustion

The compressed air enters the combustion chamber following the compression process. An injector is built into this chamber, where it injects fuel into the combustion chamber and mixes it with air. When the air and fuel mixture is ready, the chamber ignites it. The ignition process transforms this mixture into high-temperature and high-pressure gases.

Turbine

Some of the gas’s energy is converted into mechanical energy as it enters the turbine section, and some of it is expended. The turbine blades rotate as the combustion gas expands through it. The rotating blades serve two purposes: they drive a gas generator attached to the turbine and operate a compressor to bring in more air for operation.

Electricity Generation

The turbine shaft is connected to a generator, which converts mechanical energy from the turbine into electrical energy.

Gas Turbine Working & Operation Principle

The Brayton cycle or Joule cycle plays a key role in the operation of gas turbines. According to the Brayton cycle, it is a thermodynamic cycle that explains how a specific heat engine works and uses gas or air as its working fluid. It is occasionally referred to as the Joule cycle. The air-fuel mixture is burned during this Brayton cycle, pressurized, supplied, and discharged through a turbine. The compressor in the turbine raises the air pressure before it enters the combustion chamber once the air enters the turbine’s inlet. Then, to create an expanding gas, the compressed air is combined with fuel and ignited. Finally, this hot gas turns the turbine and generates electricity.

Types of Gas Turbine

There are different types of gas turbine which include the following.

• Turbojet Gas Turbine.
• Turboprop Gas Turbine.
• Turbofan Gas Turbine.
• Turboshaft Gas Turbine.

Turbojet Gas Turbine

The first gas turbines were turbojets, which operate on the same principles as reciprocal engines’ intake, compression, power, and exhaust even though they have a completely different appearance.Air travels quickly toward the fuel & ignitor chamber inlet in this type of turbine. The turbine produces accelerated exhaust gases after the air has expanded. Turbojet turbines have the benefits of being compact, light, having a straightforward design, and operating at high speeds. The drawbacks of turbojet turbines include their high noise output, poor performance at high speeds, high fuel consumption, and inability to travel over great distances.

Turboprop Gas Turbine

This particular type of turbine has a turbine, a compressor, a reduction gearbox, an intake, a combustor, and a propelling nozzle. Most small, medium commuter, and large aircraft use this turbine. Because the best propeller performance can be obtained at much lower speeds than the operational speed of the turbine, turboprop turbines require a reduction gearbox. Turboprop aircraft operate at speeds between 250 and 400 mph and altitudes between 18,000 and 30,000 feet. The altitude range between 25,000 feet and the tropopause will have the lowest fuel consumption for this turbine. Therefore, this type of turbine uses 80% to 85% of the energy it produces to drive the propeller. The exhaust gases are eliminated by using the available energy that is still available.

The benefits of turboprops include their availability with less weight, small size, and best efficiency for short distances, as well as their lower fuel consumption per hour compared to jet engines. The drawbacks of turboprops include their slower speed, loud noise, high altitude, loss of efficiency, and unsuitability for lengthy trips.

Turbofan Gas Turbine

When the jet engine generates power through a ducted fan then it is known as a turbofan turbine. It is a hybrid between a fan and a turbine. In a turbofan turbine, the fan receives power from the turbine while the turbine receives mechanical power from the combustion chamber. Through a duct fan, the turbofan turbine can easily be connected to the front side of the turbojet turbine. The fan then generates an additional push to cool the turbine and lower noise production. In aircraft, these turbines are used. While a turbofan has some benefits, such as using less fuel, making less noise, and being appropriate for long-distance travel, it also has some drawbacks, such as being large and requiring a ducted fan to generate power.

Turboshaft Gas Turbine

A turboshaft engine is one in which the gas turbine is tuned to produce shaft power as opposed to jet propulsion. When compared to a turbojet type, the turboshaft engine’s working principle is remarkably similar. The primary difference between a turboshaft and a turbojet is that the turbine in a turboshaft is powered by the highest amount of energy produced by the expanding gas rather than by the gas itself, which is used to generate thrust in a turbojet. These turbines are used in situations where compactness, light weight, consistent high performance, and high reliability are necessary. The majority of helicopters, large aircraft, and natural gas liquefaction facilities use turboshaft engines.

Turboshafts have high reliability, are available in small sizes, and consistently perform at high levels. On the other hand, they are noisy, require a lot of power to start, and are expensive to produce.

Advantages

The advantages of gas turbines include the following.

• Easily transport.
• Quick to start.
• Less cost.
• It uses different fuels.
• Lubricants consumption is low.
• High reliability.
• Less operation cost.
• Its power density is high.
• It has high accessibility.
• It generates less toxic gases.

Disadvantages

The disadvantages of gas turbines include the following.

• The power-weight ratio is less.
• Maintenance cost is high.
• Due to the use of Exotic-materials, the core engine costs are high.
• It takes more time to start at the beginning.
• The compressor must be spun by an exterior unit in order to activate the turbine.
• Since the compressor needs more power to run, its output is low.
• Because the majority of the heat is contained in the exhaust gases, this turbine’s overall efficiency is lower.

Applications

The applications of gas turbines include the following.

• Wherever maximum speed and power are required, these turbines can be used.
• Used as population unit in ships.
• These are used within jet population unit of aircraft.
• In locomotives.
• Used in the supercharging system of automobiles.
• These are used to drive generators & to power pumps.
• These turbines are used in trains & also to drive aircraft & ships.