Nuclear and coal based thermal power plants together produce almost half of the world's power
The turbines Lie at the heart of these power plants they convert thermal energy in the steam to mechanical energy
This video will explain the inner workings of the steam turbines, and why they are constructed in the manner. They [are] in a step-by-step
logical Manner
To understand its basic workings. Let's first observe one of their blades
You can see that the blade of a steam turbine has an airfoil shape
When the high energy fluid passes over it this airfoil. Shape will create a pressure difference this will subsequently create lift force
The Lift Force will rotate the turbine
Short the Energy in the fluid transfers to the mechanical energy [of] the rotor
To further understand steam turbine operation let's understand fluent energy and greater death
A fluid has three forms of energy due [to] its speed
pressure
Richer as the blades absorb energy from the fluid all three forms of energy come down
The low Velocity Jet is of no use to produce effective lift force
To increase velocity the fluid is passed through a stator section
The stator set is stationary and attached to the turbine casing you can see that flow area decreases along the stator and the speed Thus
increases
In short the stator acts like a nozzle as the speed of the jet increases in the stator kinetic energy
Increases as there is no net energy
Transfer in the fluid [in] Stator section the pressure and temperature [of] the jet should decrease to keep the total energy constant
Now the next row of rotors is added
The stator also makes sure that the flow coming out of it will be at an optimum angle of attack to the next rotor set
After that another nozzle set is added
Many such sets are used in a steam turbine
There is an important term while designing steam turbines namely degree of reaction
This term is calculated by dividing pressure and temperature energy by the total energy change in the rotor
Pressure and temperature energy together is called Enthalpy the degree of reaction decides what type of steam turbine it is
the pressure of the steam Undergoes a drastic reduction during steam turbine operation its volume increases proportionally to
Accommodate such an expanded steam. We have to increase the flow area
The flow speed will become too high this is the reason why the steam turbine blades are too long towards the outlet
You can see how long the last stage turbine blades are compared to the first stage blades
The tips of such long blades will have very high velocity compared to the root a twist is given to it so that all blade
Cross-sections will remain at an optimum angle of attack
This kind of large turbine uses to such symmetrical units
You can see how the steam is equally divided between these units
High capacity power plants use different stages of steam turbines such as high-pressure turbine
intermediate pressure turbine and low pressure turbines
All these units are attached to a single rotating shaft
The shaft in turn is connected to a generator
The reason for such different [stages] is quite interesting with greater steam temperature comes greater power plant efficiency
This is according to the second law of thermodynamics
But we cannot have temperature greater than 600 degrees Celsius since the turbine blade material will not withstand temperature more [than] that
Temperature of the steam decreases as it flows along the rows of the blade
Consequently a great way to increase power plant efficiency is to add more heat after the first stage
So after the first stage the steam is bypassed to the boiler and more heat is added
This is known as reheating this will increase the steam temperature again leading to higher power plant efficiency and output
One challenging problem in power plant operation is to keep the speed of the steam turbine
Constant this is important since frequency of the electricity produced is directly proportional to the generator speed however
Depending on the [loader] power demand the steam turbine speed will Vary
To keep the steam turbine speed constant a steam flow governing mechanism is used
If the steam turbine rotates at a higher speed the control valve will
Automatically reduce the steam flow rate to the turbine until the speed becomes normal if the turbine rotates at a low speed
The inverse will be done in this way the balance of power demand and power supply will be perfectly synchronized
To learn more about degree of reaction and its implications, please check the next video. Please help us at patreon.com
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