TURBINE
Introduction to Turbines:-
A turbine is a mechanical device that extracts energy from a fluid flow and
converts it into useful
Mechanical work. In thermal power plants, turbines play a critical role in
converting thermal energy
From steam or gas into mechanical energy, which drives the generator to
produce electricity. The
Development of turbines revolutionized power generation, making large-scale
electricity production
Feasible and efficient.
Types of Turbines in Thermal Power Plants:-
1. Steam Turbines: Use high-pressure steam to turn the blades.
2. Impulse Turbines: Steam expands through nozzles and impacts the
blades.
3. Reaction Turbines: Steam flows over blades, causing a pressure drop.
4. Gas Turbines: Use high-temperature combustion gases to drive the
turbine blades.
Steam turbines :-
A steam turbine is a mechanical device that extracts thermal energy from
pressurized steam and converts it into mechanical energy, usually to drive a
generator for electricity production. Steam turbines are widely used in power
plants, ships, and industrial processes.
They’re classified in several ways
1. Based on Steam Flow Direction:-
Axial Flow Turbine:-
Steam flows parallel to the turbine shaft. (Most common)
Radial Flow Turbine:-
Steam flows perpendicular to the shaft, either inward or outward.
2. Based on Energy Conversion Mechanism:-
Impulse Turbine:-
Steam expands and accelerates through stationary nozzles, hitting blades at
high speed
Reaction Turbine:- Steam expands partially in both fixed and moving blades,
causing pressure drops across both
3. Based on Pressure Stages:-
Single-Stage Turbine:-Steam expands in one set of blades.
Multi-Stage Turbine:-
Steam expands across multiple stages to improve efficiency.
4. Based on Exhaust Condition:-
Condensing Turbine:-
Exhaust steam goes into a condenser, creating a vacuum for maximum energy
extraction.
Back-Pressure Turbine:-
Exhaust steam is used for industrial processes
Extraction Turbine:-
Part of the steam is extracted for process needs, while the rest continues
through the turbine.
5. Based on Shaft Arrangement:-
Single-Shaft Turbine:-
One shaft connected to the generator or load.
Multi-Shaft Turbine:-
Multiple shafts for different pressure stages (common in large power plants).
6. Based on Steam Condition:-
High-Pressure Turbine (HP):- Handles high-pressure, high-temperature
steam.
Intermediate-Pressure Turbine (IP):-Handles medium-pressure steam after
partial expansion.
Low-Pressure Turbine (LP):- Handles low-pressure, expanded steam, often in
large, wide blades.
1. Impulse Turbine
Working Principle:
Converts the kinetic energy of a fluid into mechanical energy.
High-pressure fluid is directed through nozzles, which convert pressure
energy into velocity.
The fast-moving fluid hits the turbine blades, causing them to spin due to the
impact force.
Key Features:
Pressure drops completely in the nozzles (blades only change the fluid’s
direction).
Blades are typically bucket-shaped.
Can operate without being submerged in fluid.
Examples:
Pelton wheel (used in hydroelectric power plants).
De Laval turbine.
2 . Reaction Turbine
Working Principle:
Converts both pressure and kinetic energy of a fluid into mechanical energy.
The fluid flows over the blades, causing them to move due to both impulse and
reaction forces.
Pressure gradually drops as fluid passes through the blades.
Key Features:
Pressure drops occur in both the stationary and moving blades.
Blades are airfoil-shaped to create lift (like airplane wings).
Must be fully submerged in fluid to work properly.
Examples:
Francis turbine.
Kaplan turbine.
