2. CC
AIR
INLET
GAS INLET
G
HP IP LP
HRSG
STACK
CONDENSER
PUMP
TURBINE
G
T=5500C
T=8500C
T=1500C
T=500C
T=1000C
T=5000C
T=600C T=500C
T=500C
P=1bar
P=10bar
P=10bar
P=2bar
P=170bar
P=.1 bar P=1bar
COMBINED CYCLE POWER PLANT
4. Types of HRSG
• Basic types of standard design of heat recovery steam
generators are differentiated by the direction of the flue gases
flow.
• Vertical HRSG
• Small footprint
• Simple concept of service
• Hanging design of heating surfaces
• Horizontal HRSG
• Small construction height
• High cycling ability
• Operational flexibility
• Hanging design of heating surfaces
18. •This configuration is very
popular for HRSG units
recovering heat from small gas
turbines and diesel engines.
•It is a very compact design
and can be shipped totally
assembled.
•It is limited, however, since
the bent tube arrangement
quickly causes the module to
exceed shipping limitations for
units having a large gas flow
19. O-Frame evaporator layout.
This configuration has
probably been used for more
years than any of the others.
It has the advantage of the
upper header being configured
as the steam separation drum.
Or, the upper header can be
connected to the steam drum
by risers, allowing more than
one O-Frame evaporator to be
connected to the same steam
drum, resulting in shipable
modules being able to handle
very large gas flows.
20. A-Frame evaporator layout.
This configuration is simply a
variation of the O-Frame
Evaporator.
It was popular for services with
a large amount of ash, since
the center area between the
lower drums could be
configured as a hopper to
collect and remove solid
particles.
21. I-Frame evaporator layout.
In the past twenty years, this
configuration has become the most
popular.
This type module can be built in
multiple axial modules or in multiple
lateral modules, allowing it to be
designed to accept any gas flow.
There are numerous variations of
this design where tube bundles may
contain one, two, or three rows of
tubes per header. It is also,
normally, more economical to
manufacture,
ship and field construct.
The tube bundles may be shipped
to field installed in the modules, or
as loose bundles which are installed
into a field erected shell.
22. Horizontal tube evaporator layout.
The horizontal tube evaporator is used, not only for heat recovery
from Gas Turbine exhaust, but for recovery from flue gases in
Refinery and Petrochemical furnaces also.
It has similar size limitations
due to shipping restrictions
similar to the O-frame
modules.
It is generally a less
expensive unit to
manufacture than the other
configurations.
32. VARIATION OFFUEL & AIR FLOW RATES
0
500
1000
1500
2000
2500
1
0
0
3
0
0
5
0
0
7
0
0
9
0
0
1
1
0
0
PLANT CAPACITY (MW)
FLOW
RATE
(Kg/Sec)
MASS OF FUEL
MASS OF AIR
33. VARIATION OF MASS FLOW RATES IN HRSG WITH PLANT CAPACITY
0
50
100
150
200
250
300
350
100 300 500 700 900 1100
PLANT CAPACITY (MW)
MASS
FLOW
RATE
OF
STEAM
(KG/SEC)
HP MASS
IP MASS
LP MASS
36. VARIATION OF NUMBER OFTUBES IN HRSG WITH CAPACITY
1000
2000
3000
4000
5000
6000
7000
8000
100 150 200 250 300
CAPACITY (MW)
NO.
OF
TUBES
HP
IP
LP
37. Today’s Limits
• Limits are, in this case, meant to be state of the art
values of key performance factors of a HRSG application
• limits driven by economical and technical considerations.
• Triple Pressure Reheat Drum Type Boilers, natural
circulation: