S.1 Steam Injection Gas Turbine Cycle
Already in the early 20th century it was known that water injection into the
combustion chamber could increase the turbine work in a gas turbine.
In 1903 Aegidus Elling constructed the first gas turbine which was able to give
a net power output and this turbine used water injection to compensate for its
poorly functioning compressor
The research on improvements of
power cycles became intensive
during 1970’s, due to the oil crisis
and increased awareness of
negative environmental effects
from power generation.
During this period the steam
injection gas turbine was
developed.
Example of a steam injection power cycle
with supplementary firing (Cheng-cycle).
P1.1 Acknowledgements
Author: Catharina Erlich, 1999. Updated and modified in year 2007 by Catharina
Erlich. Calculation exercises created by Catharina Erlich during 2005 - 2007.
Reviewer: First Name Last Name, Affiliation, Year
P1.2 Literature
Annerwall, K, 1990; “Gas Turbines with Steam Injection or Evaporative
Regeneration” Licentiate Thesis, Energy Processes, KET/KTH, Stockholm, Sweden
Bathie, W.W., 1996; “Fundamentals of Gas Turbines”, Second Edition, John Wiley &
Sons, Inc, USA , ISBN 0-471-31122-7
Cheng, DY. and Saad, MA 1996; “The New LM2500 CHENG Cycle for Power
Generation and Cogeneration”, ECOS’96, June 25-27, STOCKHOLM. Energy
Conversion and Management Proceedings of the 1996 International Symposium on
Efficiency, Costs, Optimization, Simulation and Environmental Aspects of Energy
Systems, p 1637-1646, ISSN: 0196-8904 CODEN: ECMADL
Hunyadi, L. 1994; “Overview of Different Power Cycles”, Lecture notes, Chair of
Heat & Power Technology, EGI/KTH, Stockholm, Sweden
1
Rosén, PM 1993; “Evaporative gas turbine cycles-A thermodynamic evaluation of
their potential”, Dep. of Heat and Power Engineering, LTH, Lund, Sweden, ISSN
0282-1990
Wester, L. 1990; “Kraftcyckler”, Lecture notes, Mälardalens Högskola, Västerås,
Sweden
Wingård, S. 1990; “Ånginsprutning i gasturbiner för kraft- och värmeproduktion” ,
Licentiate Thesis, Energy Conversion, Energy Technology /CTH, Gothenburg,
Sweden, ISBN: 99-092-4232-X
Ågren, N., 1997; “Simulation and Design of Advanced Air/Water Mixture Gas Turbine
Cycles”, Licentiate Thesis, Energy Processes, KET/KTH, Stockholm, Sweden, ISSN
1104-3466
P1.3 Prerequisites
Basic thermodynamics (at least 160 LU = 4 weeks of fulltime studies),
At least one year of studies in an engineering career at university level.
The Compedu books:
S1B2 Steam Cycles
S1B3 Gas Turbine Cycles
S1B4 Commercial Combined Cycles
P1.4 LU and TU
Learning Units: 9 h
Teaching Units: 3 h (including open-ended calculation exercises)
Explanation:
Learning Units (LU) correspond to estimated number of hours for self-learning.
Teaching Units (TU) correspond to estimated number of hours for teacher to present
the material.
2
P1.5 The first gas turbine
combustor (g)
g
water (e)
f
turbine (c)
compressor
(d)
e
c
d
fuel
(h)
water (e)
air
d
regenerator (f)
e
The water injected gas turbine by Aegidus Elling
Water was injected between the compressor-stages (d) where it partly evaporated.
The rest of the water was evaporated in the regenerator (f). Thereafter the steam
and air were heated in the combustion chamber (g), expanded in the turbine (c)
and finally cooled in the regenerator (f).
The first in practice working gas turbine was built by Aegidus Elling and operated
for the first time in 1903.
This gas turbine consisted of a radial compressor, a combustion chamber, a heat
exchanger and a radial-inflow turbine and used water injection to compensate for
the poorly functioning compressor.
The net power output of this gas turbine was about 8 kW.
S.2 Educational Objectives
After this chapter the student should be able to:
Describe the concept of the steam injection gas turbine cycle
Know and understand the limitations the steam injection gas turbine
Perform a thermodynamic analysis of the steam injection gas turbine cycle
3
S.3 Working principle of the Steam Injected Gas Turbine
Gas Turbine Cycle
Fuel
Air
Steam generated from heat recovery
is injected in the combustion
chamber of a gas turbine increasing
the flow through the turbine.
Superheated
steam
Steam injection increases the power
output of a gas turbine and the
electrical efficiency.
Heat Recovery Steam
Generator
Steam injection reduces the NOX
emission in a gas turbine.
The steam injection gas turbine has
lower investment cost than a
common combined cycle and is
suitable for process industries, due
to flexible operation conditions.
Water
Treatment
There are limitations of the amount
of steam that can be injected.
Process
Make-up water
The steam injected gas turbine
consumes water and requires a flow
flexible gas turbine.
Flow-scheme of a steam injected gas
turbine
P3.1 Is injected
The steam entering the combustor is at superheated condition, being an energy
carrier of recovered heat from the hot exhaust.
The steam is assumed not to participate in the chemical reactions of the
combustion.
The injected steam will be heated with the rest of the gases to the turbine inlet
temperature.
The pressure of the steam when injected must be somewhat higher than the
pressure of air coming from the combustor.
Steam staying in superheated state can be modeled as an ideal gas.
To keep the turbine inlet temperature, more fuel is added in a steam injection gas
turbine to make up for the increased mass in the combustion chamber
4
P3.2 Increases the power output
The gross power output of a gas turbine could generally be written as:
[
]
PGT = m& ⋅ c p ⋅ (Tin − Tout ) − Pc
When steam is injected before the turbine, the mass flow through, m, will be higher
than without steam injection.
The specific heat of steam in superheated form is about twice as large as the
specific heat of the combustion gases; therefore also the average cp for the gas
mixture passing the turbine will be higher than without steam injection.
The compressor work, PC, is virtually not being affected by the steam injection
The turbine inlet temperature is set to be the same as without injection and the
outlet temperature of the turbine will remain at a similar value.
The conclusion is thus that the power output of the steam injection gas turbine will
be higher than for the same gas turbine without injection.
P3.3 And the electrical efficiency
The electrical efficiency of a gas turbine is:
P
η EL = & GT
Q
FUEL
For a steam injection gas turbine, the gain in power output is relatively large, but
this depends on the steam injection temperature as well as the amount of steam
injected.
To keep a constant turbine inlet temperature, the amount of fuel supplied in the
combustor is larger for a steam injection gas turbine compared to a common gas
turbine to cover the increase of mass to be heated.
However, the superheated steam, which is injected in the combustion chamber,
contains significant amount of energy that has been recovered from the hot gas
turbine exhaust in the HRSG.
The increase of fuel power in a steam injection gas turbine will thus be smaller
than the gain in net power output of the gas turbine, which gives that the efficiency
will increase.
Shortly said; energy is recovered in the HRSG and brought back to the gas turbine
generating additional electricity with help of the energy carrier: water-to-steam.
A steam-injected gas turbine can reach an electrical efficiency of 40% - 45 %
(maximum steam injection).
5
However, the steam injection gas turbine cannot reach the high electrical
efficiency of a combined cycle since water in vapor form leaves in the stack and
thus the water vaporization (latent) heat of the gas/steam flow is lost.
P3.4 NOX emission
By injecting steam in the combustion zone, the peaks in flame temperature are
decreased.
In high temperature spots in combination with a high air excess factor (which gas
turbines usually have), thermal NOX production takes place, where O2 and N2 in the
air react with each other according to:
N2(air) + O2(air) Æ 2 NO
This reaction is temperature dependent, and the rate increases exponentially with
temperature. The rate becomes significant for an air temperature higher than about
1500°C.
Before low-NOx burners were developed, steam injection was used as a method to
reduce the thermal NOX production.
P3.5 Lower investment cost than a common combined cycle
In a combined cycle the investment cost typically is distributed as:
•
•
1/3 of the cost is for the gas turbine, which gives 2/3 of the total electrical power
output
2/3 of the cost is for the steam cycle including HRSG, steam turbine and
condenser. The steam cycle gives around 1/3 of the total electrical power
output.
For a steam injection gas turbine there is no need for a steam turbine or a
condenser system, but the efficiency is relatively high giving that the investment
cost is lower.
In the investment of a steam injection gas turbine it is needed to take into
consideration the cost of the water treatment plant (popup “consumes fresh
water”).
Comparison of investment cost for three power plants:
Simple GT
GT Combined
Cycle
Steam injection
GT
Power output (MW)
29,1
41,3
37,3
Electrical efficiency
36
51,1
46
11,6
31
20,9
398,6
750,6
560,3
Investment cost (MEuro)
Investment cost
(Euro/installed kW)
6
Table reproduced from: Kakaras et al; 2004 "Combined cycle power plant with integrated low
temperature heat (LOTHECO)"; Applied Thermal Engineering, Volume 24, Issues 11-12, Pages 16771686
To keep the investment cost low, it provides that there is no shortage of fresh
water supply. If there is not enough water available, the flue gases from the HRSG
may need to be condensed to recover the water content, and the installation cost
of this piece of equipment may be costly.
P3.6 Process industries
The steam injection gas turbine is attractive in process industries, such as paper
pulp, textile and provisions industries.
The alpha-value (α-value) is parameter used in cogeneration and is the ratio
between produced electricity and heat, i.e.:
α= &
Q
PEL
[%]
PROCESS
There are several advantages using a steam injected gas turbine in connection to
an industrial process:
ƒ
ƒ
ƒ
ƒ
ƒ
Higher efficiency than a gas turbine without steam injection
The steam injection rate can vary from 0 to 20% of air mass flow, which
means that the amount of process steam also can be varied, giving a very
flexible α-value.
The gas turbine can be operated on full or part-load, with or without
steam injection, also contributing to a very flexible α-value.
Lower capital cost than a combined cycle
Occupies less space than both a combined cycle and a steam cycle
If the industry has a large demand of steam, it is additionally possible to use
supplementary firing in the HRSG for a higher steam production.
If the HRSG is combined with a flue gas condensing unit to recover water
contained in the gas turbine exhaust and the vaporization heat of this water is
utilized as further process heat, the total cogeneration efficiency can be very high.
P3.7 Amount of steam that can be injected
The amount of steam that can be injected is highly dependent on the gas turbine
type, whether it is a one-shaft or double-shaft gas turbine and on the pressure and
temperature in the combustor.
The amount of steam injected is also dependent on the heat recovery rate in the
HRSG and on the temperature and pressure of the steam.
One limiting factor is the increased risk for compressor surge; see popup
"Requires a flow flexible gas turbine".
7
Another limiting factor is the increased risk for production of unburned
hydrocarbons (UHC) and CO, since the steam injection causes a drop in flame
temperature in the combustor.
A third limiting factor is the amount of heat available in the gas turbine exhaust in
the HRSG. If the steam is not superheated, the losses in the HRSG generally are
higher. Also, smaller gas turbines have lower combustion temperature and thus
lower exhaust temperature before the HRSG, causing a limited amount of energy
available for recovery.
T
T
Flue
gas
Flu
Vaporisation
eg
as
Vaporisation
Superheating
Enthalpy in flue gas
Enthalpy in flue gas
The losses in the HRSG are larger if no steam superheating takes place
Indirectly, the amount of steam that can be injected is also dependent on the need
of process heat in case the gas turbine is connected to an industry.
Usually, the amount of steam that maximum can be injected is in the range of 1520 % of the air mass flow.
For a gas turbine this corresponds to about 1.7 kg steam per produced kWh
electricity (when maximum amount of steam is injected and the gas turbine runs
on maximum speed).
P3.8 Consumes water
The most significant drawback of a steam injection gas turbine is that it consumes
fresh water.
The quality of the water to be used for injection is very important.
Before entering the HRSG, the water passes treatment plant in order to remove
salts and other contaminants, which can cause corrosion both in the turbine and in
the HRSG.
The steam, which is injected in the combustion chamber of the gas turbine, is
blended with the combustion gases, and will follow the gas steam to the stack.
If no flue gas condensing is performed, the water is lost in the atmosphere.
If flue gas condensing is employed, up to 75% of the water can be recovered if the
flue gas exiting the HRSG is cooled down to 50°C.
8
Also, if the plant is connected to an industry, condensed water from the process
can be recovered and re-used after cleaning.
P3.9 Requires a flow flexible turbine
In reality, the steam-injection affects the function of both the turbine and
compressor.
Steam-injection gives a larger risk for compressor surge.
Compressor surge means that the gases from the combustion chamber turns
direction and flows through the compressor leading to an intermediate breakdown.
If the flow through the turbine is increased, the pressure drop over the turbine is
also increased.
This means as well that the compressor is forced to work with an increased
pressure ratio.
Consequence for a one-shaft turbine
Consequence for a double-shaft turbine
P3.9.1
Consequence for a one-shaft turbine
Compressor performance diagram
p2 /p1
For a one-shaft gas turbine:
Surge
limit
The turbine and thus the
compressor works with constant
revolution speed, as this is set by
the electrical grid frequency (50 Hz =
3000 rpm).
n2
Increased
pressureratio
n1
Decreased
airflow
If the pressure ratio of the
compressor is forced to be higher,
the airflow will decrease, according
to the compressor performance
diagram.
massflow
When the airflow decreases along a
constant rpm-curve, the compressor
approaches the limit for surge.
The steam injection rate must be
limited so that a marginal to the
surge limit is kept.
Typical compressor performance diagram
9
P3.9.2
Consequence for a double-shaft turbine
Compressor performance diagram
p2 /p1
Increased
pressureratio
For a double-shaft gas turbine:
Surge
limit
In a double-shaft gas turbine, the
compressor and the turbine are
placed on separate shafts, and have
different revolution speeds (turbine is
however connected to the generator
frequency).
n2
n1
Increased
airflow
If the pressure ratio over the turbine
increases, the pressure ratio over the
compressor will as well increase.
massflow
However, the compressor can
compensate for the increased
pressure ratio by increasing the
revolution speed.
The airflow with then increase, and
the risk for compressor surge is
minimized.
The steam injection rate is in this
case limited by the maximum speed
of the compressor.
Typical compressor performance
diagram
10
S.4 Analysis of the Steam Injected Gas Turbine
Gas Turbine Cycle
1
Superheated
steam
d
Fuel
Air
2
3
Heat Recovery Steam
Generator
6
Fuel, steam and air are supplied in
the combustion chamber forming a
steam/gas mixture at high
temperature.
4
The gas/steam mixture expands in
the turbine.
5
7
a
b
c
Air is compressed in the
compressor.
Steam is generated in the HRSG,
while cooling the gas/steam
exhaust.
d
Net power output and efficiency of
the steam injected gas turbine.
Flow-scheme of a steam injected gas
turbine
P4.1 Air is compressed
The compressor power input is virtually not affected by the steam injection
The compressor power need can thus be modeled in the same way as for a gas
turbine without steam injection.
The power input into the compressor is:
& AIR ⋅ ( h 2, AIR − h 1, AIR )
PC = m
[kW]
The temperature increase of the air during the compression is:
κ C −1
⎞
T1 ⎛⎜ p 2 κ C
⋅ ( )
− 1⎟
T2 − T1 =
⎟
η SC ⎜⎝ p1
⎠
[°C or K]
The ratio of specific heats for air, κ, is dependent on the temperature.
The isentropic efficiency of the compressor, ηSC, is assumed to remain unchanged
with the steam injection.
11
P4.2 Forming a gas/steam mixture at high temperature
The steam injected is not taking active part in the combustion process, but will be
heated to the same temperature as the rest of the gas, i.e. to the turbine inlet
temperature.
The fuel flow needed to bring the gas/steam mixture up to this temperature is
found from a heat balance similarly made as for a gas turbine without steam
injection.
Since the steam is not reacting in the combustion process, the gas and steam
flows can be treated separately.
The heat balance thus becomes:
& AIR · h 2, AIR + m
& FUEL· LHV+ m
& ST · h d,ST = (m
& AIR + m
& FUEL) · h 3, GAS + m
& ST · h 3, ST
m
[kW]
The gas enthalpy is found in the same way as for the common gas turbine:
h3, GAS = h3, AIR + x·DH3
where the gas content, x, is based on the gas part of the flow:
x = (1 + f ) ⋅
β
1+ β
The specific fuel consumption, β, is defined identically as for the common gas
turbine:
β=
& FUEL
m
& AIR
m
[kg fuel/kg air]
Inserting the expressions of the gas content and the specific fuel consumption,
and dividing with mAIR, the heat balance equation becomes:
h 2, AIR + β · LHV +
& ST
&
m
m
· h d,ST = h 3, AIR + β ⋅ [h 3, AIR + (1 + f ) ⋅ DH 3 ]⋅ + ST · h 3, ST
& AIR
& AIR
m
m
Solving for the specific fuel consumption, β:
β =
& ST
m
⋅ ( h 3, ST − h d, ST )
&
m AIR
LHV − h 3, AIR − (1 + f ) ⋅ DH 3
h 3, AIR − h 2, AIR +
[kg fuel/kg air]
Comparing this expression for the specific fuel consumption with the one for the
basic gas turbine cycle, it is seen that the ratio is identical except from the extra
term which represents the heating of steam from the injection temperature up to
the turbine inlet temperature.
12
Thus, to compensate for the additional heating in the combustor, the fuel flow for a
steam injected gas turbine is higher than for gas turbine without injection for the
same turbine inlet temperature and compressor performance.
Very often, steam tables do not treat steam temperatures over 800°C or 900°C, and
since the steam, which is injected in the gas turbine, reaches the turbine inlet
temperature (often higher than 1000°C) it may be suitable to introduce a diagram
"Specific heat for superheated steam"
The term for steam heating can also be expressed as function of specific heat and
temperature increase:
( h 3, ST − h d, ST ) = c P ,ST ⋅ (T3 − Td )
[kJ/kg]
where the specific heat of superheated steam, cP,ST, is taken at the pressure prevailing
in the combustor and the mean temperature of heating, i.e.
Tm =
T3 + Td
2
P4.2.1
Specific heat for superheated steam
Specific heat, Cp, for superheated steam (H2O)
3900
1 bar
3700
5 bar
Specific heat (J/kg deg C)
3500
10 bar
3300
20 bar
3100
30 bar
2900
60 bar
2700
100 bar
2500
2300
160 bar
2100
Saturation
line
1900
0
100
200
300
400
500
Temperature (deg C)
13
600
700
800
P4.3 The gas/steam mixture expands
Similarly as for the heat balance on the combustion chamber, the steam and gas
flows can be treated separately when modeling the expansion.
The turbine power gets contribution both from the expanding gas and from the
expanding steam.
The turbine power can thus be expressed as:
& AIR + m
& FUEL ) ⋅ (h 3, GAS − h 4, GAS ) + m
& ST ⋅ ( h 3, ST − h 4, ST )
PT = (m
[kW]
Where
h3, GAS = h3, AIR + x·DH3
h4, GAS = h4, AIR + x·DH4
and the gas content, x, is:
x = (1 + f ) ⋅
β
1+ β
Since the specific fuel consumption, β, becomes higher in a steam injected gas
turbine, the gas content will also be higher.
The steam expansion can also be modeled in terms of specific heat (if the turbine
inlet temperature is high):
(h 3, ST − h 4, ST ) = c P ,ST ⋅ (T3 − T4 )
[kJ/kg]
where the specific heat of superheated steam, cP,ST, is taken at the average
pressure and temperature of the expansion, i.e.
pm =
p3 + p 4
T3 + T4
and Tm =
2
2
The temperature decrease during the expansion can be modeled as without steam
injection, as steam staying in superheated form can be assumed to behave as an
ideal gas.
The temperature decrease thus becomes:
T3 − T4 = T3 ⋅η ST
⎛
⎞
⎜
⎟
⎜
⎟
1
⋅ ⎜1 −
κT −1 ⎟
p
⎜ ( 3 ) κT ⎟
⎜
⎟
p4
⎝
⎠
[°C or K]
The ratio of specific heats, κ, is dependent on the temperature, on the gas content
and on the steam.
14
To simplify the model for temperature decrease, it is assumed that the ratio of
specific heats, κ, is dependent only on the gas content and on the temperature
decrease.
Since the gas content, x, is increased with the steam injection, the ratio of specific
heats, κ, will be somewhat lower compared to a gas turbine without steam
injection.
It is furthermore assumed that the isentropic efficiency of the turbine, ηST, stays
unchanged with the steam injection.
P4.4 Steam is generated
Commonly, the heat recovery steam generator is built up similarly to the combined
cycle, i.e. an economizer heating pressurized water, an evaporator generating
steam from water and a superheater bringing the steam to superheated state.
The water entering the economizer is pumped to a pressure somewhat higher than
the compressor pressure.
The heat recovery rate to the steam cycle is:
& ST ⋅ (h d, ST − h a, ST )
Q& rec = m
[kW]
(A)
The heat recovery rate for each heat exchanger is:
Economizer:
& ST ⋅ ( h b, ST − h a, ST )
Q& eco = m
(B)
Evaporator:
& ST ⋅ (h c, ST − h b, ST )
Q& vap = m
(C)
Superheater
& ST ⋅ ( h d, ST − h c, ST )
Q& sup = m
(D)
To make energy balances in the HRSG, the equations (A’-D’) under popup “Cooling
the gas/steam exhaust” are put equal to the equations (A-D) above so that A=A’, B=B’,
C=C’ and D=D’.
P4.5 Cooling the gas/steam exhaust
Steam for injection is generated from heat recovery of the gas/steam exhaust.
Similarly as for both the heat balance on the combustor and as for the expansion
in the turbine, the gas/steam mixture can be treated as two separate flows.
The total gas cooling rate on the gas side in the HRSG can be expressed as:
15
& AIR + m
& FUEL ) ⋅ (h 4, GAS − h 7, GAS ) + m
& ST ⋅ (h 4, ST − h 7, ST ) [kW]
Q& rec = (m
(A’)
In terms of specific heats and temperatures, the gas cooling rate can also be
expressed as:
& AIR + m
& FUEL) ⋅ cP,GAS + m
& ST ⋅ cP,ST ]⋅ (T4 − T7 )
Q&rec = [(m
[kW]
(A’’)
For each heat exchanger the gas cooling rate is:
Economizer:
& AIR + m
& FUEL ) ⋅ (h 6, GAS − h 7, GAS ) + m
& ST ⋅ (h 6, ST − h 7, ST )
Q& eco = (m
(B’)
Evaporator:
& AIR + m
& FUEL ) ⋅ ( h 5, GAS − h 6, GAS ) + m
& ST ⋅ ( h 5, ST − h 6, ST )
Q& vap = ( m
(C’)
Superheater:
& AIR + m
& FUEL ) ⋅ (h 4, GAS − h 5, GAS ) + m
& ST ⋅ (h 4, ST − h 5, ST )
Q& sup = (m
(D’)
To make energy balances in the HRSG, the equations (A-D) under popup “Steam is
generated” are put equal to the equations (A’-D’) above so that A=A’, B=B’, C=C’ and
D=D’.
P4.6 Net power output and efficiency of the steam injected gas
turbine
The net power output of the steam injected gas turbine is expressed in the same
way as for the simple gas turbine:
PSTGT = ηG · (PT· ηm – PC)
[MW or kW]
The electrical efficiency of the steam injected gas turbine is
η EL =
PSTGT − PPUMP
PSTGT
≈
&
& AIR ⋅ LHV
Q
β ⋅m
FUEL
[%]
The pump work of the liquid water before entering the HRSG is significantly less than
the compressor work of the gas turbine; therefore the pump work can be neglected.
If steam produced in the HRSG also is brought to an industrial process, the total
(cogeneration) efficiency becomes:
ηTOT
&
PSTGT + Q
PROCESS
=
& AIR ⋅ LHV
β ⋅m
[%]
16
S.5 Calculation exercises
Here there are a number of calculation exercises with solutions for download in PDFformat.
1. Steam injection gas turbine fired on natural gas
2. Steam injection gas turbine with the gas content, x, given
3. Steam injection gas turbine using high turbine inlet temperature
4. Steam injection gas turbine with heat balance on the HRSG
5. Steam injection gas turbine with given net power output
S.6 Summary
In a steam injection gas turbine, steam is generated by heat recovery of the hot
gas turbine exhaust and thereafter injected in the gas turbine combustor, where it
is heated up to the turbine inlet temperature.
The steam injection leads to a higher mass flow through the turbine and thus
increases the net power output compared to a gas turbine without steam injection.
The efficiency of a steam injection gas turbine is also higher compared to a
common gas turbine since the heat recovered from the hot gas turbine exhaust is
brought back to the expansion.
In reality, the increased flow in the turbine causes an increased pressure drop,
which also leads to that the compressor needs to work with a higher pressure
ratio.
The maximum steam injection rate is about 15-20% of the air mass flow.
The steam injection gas turbine consumes water but some of the water content in
the gases can be recovered if flue gas condensing is employed.
A thermodynamic analysis of a steam injection gas turbine is similar to the one of
a common gas turbine and simplified by treating the gas/steam flow as two
separate working media.
17