This slideshare has been developed for Engineers entering the Power industry, and enthusiasts of power technology. It covers the basic history, theory, operation and importance of steam turbines from a mechanical viewpoint.

1. Steam Turbine Fundamentals
An introductory guide to the operation of modern steam turbines
v. 1.0
1

2. About the presentation
This presentation teaches the reader about the operation and importance of steam turbines in electricity
generation.
Readers will become familiar with the key components of a steam turbine, and be able to describe how the
complete system works.
It is suitable for engineers entering the power industry, and keen enthusiasts of power systems.
Note that it assumes some basic knowledge of electrical and thermodynamic systems.
Foreword
2

3. ► Invention attributed to Sir Charles Parsons in 1884.
► First compound (multi‐stage) turbine developed in 1887.
► A majority of the world’s power today is produced by steam turbines from a variety of fuels
including:
• Coal
• Nuclear
• Oil
• Concentrated Solar
• Geothermal
► Some major manufacturers include:
• Siemens
• Toshiba
• Alstom
• General Electric
History
3

4. Basic Principles
What they do
► Steam turbines are used for stable, high output electricity needs. Modern units
can exceed 1GW from a single system.
► They are coupled to AC generators and run at constant speed (usually
3,000rpm) which creates a reliable frequency (50Hz Australia, 60Hz USA) and
stable output power.
4

5. Basic Principles
How they do it
► Boilers create superheated steam which is
used to spin a turbine.
► Steam turbine operation is based on the
Rankine cycle with 4 key stages:
• 1‐2: Pressurise
• 2‐3: Heat
• 3‐4: Expand
• 4‐1: Condense
Boilers ‘pressurise’ and ‘heat’,
Turbines ‘expand’ and ‘condense’.
5

6. Importance of steam turbines
Pro’s
• Very stable base load
• High level of control over electricity output
• Very high output from single machines (up to 1GW+)
• Serviceable life can be in excess of 30 years
• Very diverse. Can use a wide range of power sources to generate steam
Con’s
• Long start up and shut down times. Not ideal for peak loading
• High capital expense. Generally viable only in large scale installations
• Minimal redundancy. Taking a single unit offline can take up to 1GW of
power off a grid
• Maintenance intensive. Require full time maintenance technicians and
engineers to operate.
Basic Principles
6

7. Turbine Layout
Steam path indicated in blue.
7
Read on for a breakdown of each component

8. 1 ‐ Boiler
Water is pressurised and superheated to set conditions, generally:
• 600+ deg C*
• 15+MPa*
Steam passes through a series of protection valves:
• Main isolation shuts down the system in an emergency
• Governor valves regulate the inlet steam for consistent operation
*typical value. Will vary depending on manufacturer, machine size, and age.
8

9. 2 – HP Turbine
Steam enters the HP (high pressure) turbine through nozzles.
Mechanical energy is generated by the steam passing over a series of fixed and rotating blades.
Fixed blades on the stator guide steam through the rotor blades, causing the rotor to turn.
The steam expands and cools as it moves through the blades.
Steam leaves at a reduced pressure and temperature, approximately:
• 350 degC*
• 7 MPa*
9
*typical value. Will vary depending on manufacturer, machine size, and age.

10. 3 – Re‐heat
Steam re‐enters the boiler through a dedicated ‘re‐heat’ system.
This raises the steam back to inlet temperature, but does not change
pressure.
10

11. 4 – IP Turbine
Re‐heated steam enters the IP (intermediate pressure) turbine under the re‐
heated conditions, approximately:
• 600+ deg C*
• 6‐7 MPa*
Steam exits the IP turbine through the ‘cross over pipe’.
11
*typical value. Will vary depending on manufacturer, machine size, and age.

12. 5 – LP Turbine
Steam from the cross over pipe enters the centre of the LP (low pressure)
turbine at a further reduced pressure and temperature, approximately:
• 350deg C*
• 900 kPa*
Steam expands out in both directions along the IP blades. By the last set of
blades, the steam has lost enough energy that it is no longer superheated.
12
*typical value. Will vary depending on manufacturer, machine size, and age.

13. 6 ‐ Condenser
The condenser rapidly cools the steam leaving the LP turbine.
As the steam condenses, it vastly reduces its volume, creating a vacuum. Condenser
conditions may be approximately:
• 40 deg C*
• 10 kPa(abs) *
This vacuum draws steam through the LP turbine, extracting more mechanical power.
13
*typical value. Will vary depending on manufacturer, machine size, and age.

14. 7 – Return to Boiler
Condensed water is passed through a series of pre‐heaters on its way back to
the main boiler.
Though it may seem counter‐intuitive to deliberately cool the steam in the
condenser only to re‐heat it again, a more in depth analysis of the
thermodynamics and re‐heat process will show that this increases the
efficiency of the system.
14

15. 8 ‐ Generator
The turbine extracts power simultaneously from the HP, IP and LP rotors.
The shaft is coupled directly to a generator. This outputs 3 phase power to a
step up transformer, and finally the electricity grid.
15

16. System Review
1. Steam is superheated to 600+ degrees C, and 15+ MPa.
2. It passes through the HP turbine, converting heat and pressure to rotating energy
3. Exit steam returns to the boiler for re‐heat, but pressure remains the same.
4. It then passes through the IP turbine at 600+ degrees C and 6MPa.
5. Steam flows through the crossover pipe, directly in to the LP turbine at 350 degrees C and
900kPa
6. Steam exists the LP turbine to the condenser, operating at 40 degrees C and 10kPa
absolute
7. The Condensed water is returned to the boiler through a series of pre‐heaters.
8. The generator is rotated by the common shaft, and outputs a consistent 3 phase load.
16

17. Further Study
Useful topics to learn
from here:
• Impulse vs. Reaction turbines
• Steam seals
• Re‐heat and feedwater systems
• Generator cooling systems
17

18. Joshua Lowndes
Mechanical Engineer
Perth, Australia
If you have any questions or would like to talk more on the Power
Industry in WA, I welcome you to get in touch via LinkedIn.
My name is Joshua Lowndes, I am a Mechanical Engineer from Perth, Australia. I work directly
with grid connected steam turbines, consulting in maintenance and technical support roles.
I believe steam turbines are fundamental to all large scale power generation facilities, fossil
fuel and renewable energy alike, and an understanding of them is paramount for any engineer
in the Power industry.
I welcome any feedback and I’m always open to discussion on Western Australia’s power
industry.
About the author
18
Thanks for reading!