HOW DO STEAM TURBINES WORK?

[cholaturbo]

Nuclear and coal-based thermal power plants together produce almost half of the world's electric power and steam turbines are the heart of these power plants. Steam turbines convert thermal energy into useful mechanical energy which in turn rotates the generator shafts to produce electricity. Charles Parsons first invented the modern steam turbine back in 1884.

How Do Steam Turbines Produce Electricity?

A steam turbine consists of a set of stationary and rotating blades in an airfoil shape. When high-pressure steam passes over it, a pressure difference is created due to the airfoil shape of the blade. The pressure difference creates a lifting force that rotates the turbine. Thus conversion of energy takes place that is from heat energy to mechanical energy to rotational. The rotation of the shaft drives the turbine that is connected to the generator. This is the basic steam turbine working principle and the turbine manufacturers rely on this for the best turbine design.

How Does A Steam Turbine Work?

As the name implies that it is powered by steam, high-energy steam is injected into the turbine which transforms the potential energy of the steam into kinetic energy which causes continuous rotation of the blades. Anything that can flow is fluid and hence steam is a fluid. A fluid has three forms of energy that are kinetic energy due to speed, pressure, and temperature. All these three forms of energy get reduced when the turbine blades absorb and rotate. The low velocity will be incapable of generating enough lifting force to rotate the shaft. To overcome this challenge the blades are configured in such a way that the fluids are passed through the stator section. The stators are stationary and attached to the turbine casing and their design is such that the flow area decreases along the stator, that is the area of the stator where steam enters is wide and the area of the stator where steam exits are narrow, this design creates the increase in the speed of the steam just working similar to a nozzle. Thus the kinetic energy of the steam is revived. The whole turbine is configured by this design of blades and stators combination arranged adjacently. The stator is responsible to create an optimal angle of fire to the next blade. The overall design of the turbine is done to meet the required degree of reaction.

Degree of reaction = (Pressure Energy + Temperature Energy) change in the rotor / (Total Energy change in the rotor)

The degree of reaction is used to decide the type of turbine that is an impulse turbine or reaction turbine.