COMBINED
CYCLE POWER PLANT
EXPLAINED
HANDBOOK
Second Edition, 2025
Join our newsletter if you want free access to more
engineering PDFs like this one.
⚫ saVRee ltd, 71-75 Shelton Street, Covent Garden, WC2H 9JQ, London ⚫ www.saVRee.com ⚫
contact@savree.com
Copyright © 2025 by saVRee ltd | All rights reserved. This publication or any portion thereof
may not be reproduced or used in any manner whatsoever without the express written
permission of the publisher.v1e
Table of Contents
What is a combined cycle power plant? ................................................................................. 1
What are the main parts of a combined cycle power plant? .............................................. 2
How do combined cycle power plants work? ........................................................................ 2
What is a combined cycle power plant?
A combined cycle power plant (CCPP) is a type of power plant that combines a gas
turbine and a steam turbine to generate electricity. The gas turbine is used to generate
electricity directly, and the exhaust gases from the gas turbine are used to generate
steam in a heat recovery steam generator (HRSG). The produced steam is then used
to drive a steam turbine, which also generates electricity.
Combined cycle power plants utilise both the Rankine thermodynamic cycle, and
Brayton thermodynamic cycle, hence, they are 'combined cycle' power plants. The
Rankine cycle describes the thermodynamic properties of a heat engine that uses a
fluid as the working fluid (typically steam), whilst the Brayton cycle describes the
thermodynamic cycle of a heat engine that uses a gas as the working fluid.
Combined Cycle Power Plant Schematic
Combined cycle power plants are more efficient than traditional power plants that use
only gas turbines or steam turbines; this is because combined cycle power plants utilise
the heat from a gas turbine's exhaust gases to generate steam, consequently reducing
wasted energy.
www.saVRee.com
Combined Cycle Power Plant Explained | pg. 1
Combined Cycle Efficiency (Brayton and Rankine Cycle in Series)
Good to know - a 'power plant' and 'power station' are the same thing, only the wording
is different.
What are the main parts of a combined cycle power
plant?
The main parts of a CCPP are:
•
•
•
Gas Turbine
HRSG
Steam Turbine
How do combined cycle power plants work?
The following is a simplified overview of how a combined cycle power plant works:
1. Air is drawn into the gas turbine compressor.
2. The air is compressed and then mixed with fuel in the combustor section of
the gas turbine.
3. The fuel-air mixture is ignited, and the hot exhaust gases are directed to the
turbine section of the gas turbine.
www.saVRee.com
Combined Cycle Power Plant Explained | pg. 2
4. The turbine section rotates, driving the gas turbine generator and producing
electricity.
Gas Turbine (Combustion Turbine)
5. The exhaust gases from the gas turbine are directed to a HRSG.
6. As the exhaust gases pass through the HRSG, their heat passes to the HRSG
pipes, which are full of water. The water is heated and turns to steam.
7. The produced steam is directed to a steam turbine.
8. The steam turbine rotates, driving a generator, thus producing electricity.
9. Exhaust steam from the steam turbine is condensed in a condenser and
returned to the HRSG.
Note that both the gas turbine and steam turbine are used to generate electricity. It is
however the gas turbine that produces electricity and the heat required to make steam,
which is then used to drive the steam turbine.
www.saVRee.com
Combined Cycle Power Plant Explained | pg. 3