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  • Two of the most common applications of Gas Turbines in modern industries

  • are Turbo Generators and Turbo Compressors.

  • I try to approach a Gas Turbo Generator (GTG) to better feel the subject.

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  • In a Gas Turbine Power Plant,

  • there's a Generator which is an electrical machine.

  • But to generate electricity

  • this generator needs a Prime Mover

  • which for my example is a Gas Turbine.

  • The Gas Turbine transforms the chemical energy in the fuel

  • (i.e. natural gas or the similar fuel) into mechanical energy.

  • The mechanical energy generated by the Turbine exit shaft

  • is then transferred through a gearbox to the Generator's shaft.

  • Now my generator can create electrical energy.

  • This primitive form of electrical energy normally has a low

  • or medium level of voltage

  • and to better manage the power loss in transmission lines,

  • this voltage should be increased by step-up transformers.

  • Such transformers give an adequate level of voltage to the electrical energy

  • to be transmitted through the transmission lines and delivered to the grid.

  • After this brief overview of a sample Gas Turbine application,

  • I'm going to dig down into the Gas Turbine mechanism in more detail.

  • First, imagine a rocket

  • in which some fuel is going to burn and create a high-pressure exhaust gas.

  • Based on energy conservation law,

  • the chemical energy of the fuel is transformed into mechanical energy

  • in the high-pressure exhaust gas.

  • When a rocket is fired,

  • the thrust of this exhaust gas moves the rocket forward.

  • This amount of rocket science is enough for me

  • and now suppose I fix the rocket body with a robust mechanical structure

  • to prevent its movement.

  • What will happen?

  • The high-pressure exhaust gas

  • should be released and it will have no way but backward!

  • Now keep this structure in mind

  • and imagine I put a set of turbine blades

  • in the path of this high-pressure back-fired exhaust.

  • You see that the release of mechanical energy

  • which is mostly in a “linearbackward direction

  • will mostly transform into kind ofrotationalof turbine shaft

  • and so far I'd say it's a big success,

  • i.e. transforming the chemical energy of fuel gas

  • into rotational mechanical energy of turbine shaft.

  • Now I have a “Prime Moverfor my generator

  • in the above power plant example.

  • Also, this prime mover concept can be used in different applications

  • like turbo compressors or the likes.

  • Now that I have the basics of Gas Turbines,

  • let's focus on a modern Gas Turbine and its components.

  • Most likely you know aboutFire TriangleorCombustion Triangle

  • which illustrates the necessary ingredients of fire or combustion,

  • i.e. “Fuel”, “Air”, andHeat”.

  • To transform the chemical energy of the fuel gas into mechanical energy,

  • the fuel should be burnt in theCombustion Chamberof a gas turbine,

  • so I need air and heat added to the fuel.

  • Air is let into the gas turbine throughAir Intake

  • and mixed with a proper amount of natural gas.

  • The Air/Gas ratio is determined based on the specific heating value of the gas

  • and quality of the air, amount of moisture, altitude from sea level and so on.

  • Now an ignition system steps in and makes the initial sparks,

  • whereby heat is provided.

  • When the fire is established and stabilized in the combustion chamber,

  • the ignition system will be put out of service.

  • The most critical process in normal turbine operation

  • is to manage the combustion

  • and produce a proper amount of high-pressure exhaust gas.

  • This exhaust gas is applied to the turbine blades

  • and after rotating the turbine shaft, conducted to the exhaust stack.

  • With this quick review of key components of a Gas Turbine,

  • I think it's time to decrease the altitude and elaborate on the system further.

  • As mentioned earlier, air is let into the Gas Turbine through Air Intake.

  • The air is prone to contaminations or having some unwanted particles

  • which can harm the system and degrade the overall performance.

  • The screening and filtration are basic requirements for incoming air.

  • Also, proper instrumentation is mounted on the Air Duct

  • to monitor the draft pressure and temperature.

  • In harsh environments, the air might need to be preheated or conditioned.

  • Also, differential pressure monitoring of air filters

  • will warn the turbine operator of filter clogging.

  • The conditioned air is conducted into theturbine air compressor

  • which is an axial compressor comprised of multi-stages of blades

  • mounted radially on the turbine inlet shaft.

  • The discharge pressure and temperature of the air compressor

  • are monitored to manage the combustion quality at the combustion chamber.

  • Fuel gasis a key factor in the design and operation of a gas turbine.

  • The manufacturers need to know the details of fuel gas

  • and only based on its characteristics

  • can guarantee the performance of their gas turbines.

  • Also, the pressure and temperature of fuel gas

  • are monitored during normal operation of a gas turbine.

  • There are different technologies in properly mixing the air and gas

  • and making efficient combustion from manufacturer to manufacturer.

  • Combustion chambers are of some tubular heat resistant structures

  • and fuel is usually injected into it from the circumference

  • and at different cross-sectional locations.

  • The temperatures at different locations of the combustion chamber

  • are thoroughly monitored by means of proper sensors like thermocouples.

  • This high-temperature/high-pressure zone in gas turbine structure

  • is of the highest levels of importance to monitor and control.

  • Also, the technologies used in the design and construction of the combustion chamber

  • are of the topmost ones.

  • Now that the Air/Gas mixing is well managed

  • and combustion is going on properly,

  • there is a plenty amount of high-pressure/high-temperature exhaust gas

  • generated and should be applied to the gas turbine blades

  • to make turbine exit shaft rotation feasible.

  • At this stage, the high RPM of Gas Turbine rotor

  • should be tightly monitored and based on the load driven by the turbine,

  • the surge of turbine gets the topmost importance

  • for turbine performance and turbine protection.

  • Vibrations (axial and radial) and speeds,

  • both at the air compressor and gas turbine

  • should be continuously taken into consideration.

  • This was the simplest way to address major parts of Gas Turbines

  • and as one of the most sophisticated man-made machines,

  • a Gas Turbine deserves more elaboration.

  • Also, there are different technologies which some manufacturers use

  • as their proprietary technology and were not considered in this video.

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Two of the most common applications of Gas Turbines in modern industries

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