The document discusses exergy analysis of a combined gas power station. It calculates the energy and exergy flows for various systems like the compressor, high pressure turbine, and low pressure turbine. The analysis found that the compressor had the highest exergy destruction, followed by the low pressure turbine and high pressure turbine. The conclusion is that minimizing exergy destruction in these components, especially the compressor, through proper operation and maintenance could improve the plant's efficiency.

1. Exergy Based Performance Analysis
of FGPS
OBJECTIVE
 Compute energy and exergy flows using the thermodynamic property values with the
real time operation parameters at terminal points of crucial systems and evaluate
exergy destruction at different systems.
INTRODUCTION
One major challenge in today’s traditional power generation technology lies in meeting
the rapidly changing yardsticks of economics and environmental guidelines. Economics
of power generation does not only require designing an efficient power plant, but also
following proper operation and maintenance (O&M) strategy such that the energy
conversion efficiency of the plant throughout its life cycle remains high .Efforts are also
expended to improve the efficiency (or heat rate) of existing plants through proper
monitoring and taking necessary corrective O&M measures. Often, a marginal heat rate
improvement through a suitable corrective measure at the O&M level is more desirable
than other complicated and expensive options (e.g., an elaborate retrofit).Thermal
emission to the environment is an unavoidable consequence of thermal power
generation. In the face of ever increasing stringency of the environmental norms, it is
important that the environmental impact of energy conversion process is reduced by
increasing the efficiency of energy resource utilization. Energy analysis is traditionally
used in industries to carryout performance comparisons and optimizations. The
conventional methods of energy analysis are based on the first law of thermodynamics,
which is concerned with the conservation of energy. The first law merely serves as a
necessary tool for bookkeeping of energy during a process and often casts misleading
impressions about the performance of an energy conversion device. Optimization
through conventional analysis for power cycles has reached almost the saturation level.
Achieving a high figure of cycle efficiency, therefore, warrants a higher order analysis
based on the second law of thermodynamics. The second law analysis of a power cycle
enables us to identify the major sources of loss and shows avenues for performance
improvement.
THEORY

2. Exergy is the maximum possible work that can be produced by a system as it is brought
into equilibrium with a specified reference environment. Thus exergy can be reckoned
as a measure of the quality or usefulness (capacity to effect desired change) of energy.
Unlike energy, exergy is not conserved, but it is destroyed in any practical process. The
exergy destruction during a process is proportional to the entropy generation in it, which
accounts for the inefficiencies due to irreversibility. Practical devices involving energy
conversion and transferal ways observe energy conservation law, but the quality of
energy degrades i.e. work potential is lost or exergy is destroyed. Exergy analysis helps
in identifying the process irreversibilities leading to the loss in useful work potential and
thus pinpointing the areas where improvement can be sought. Exergy is often treated as
a measure of economic value. Some researchers have portrayed costs of energy
conversion devices as functions of their exergy efficiencies. Degradation of quality of
energy is equivalent to the irretrievable destruction of exergy due to all real processes
being irreversible. The destruction of exergy provides a quantitative measure of process
in efficiency. The irreversibility rate or exergy destruction rate is a yardstick, by which
losses in the plant and it components can be quantified and compared on a rational
basis. The potential for improvement in a given component is determined by its
irreversibility rate under a given set of conditions in relation to the minimum irreversibility
rate (called intrinsic irreversibility rate) possible within the limits imposed by physical,
technological, economic and other constraints. The exergy destruction or order
destruction also leads to thermal pollution to the environment. By preserving exergy
through increased efficiency (i.e. degrading as little exergy as necessary for a process),
environmental damage is reduced. Therefore, exergy analysis is as important as energy
analysis for design, operation and maintenance of different equipment and systems of a
power plant. For a closed system, exergy at any point is given by:
Where and represent the dead state.
SALIENT POINTS
 It is a primary tool in best addressing the impact of energy resource utilization on the
environment.
 It is an effective method using the conservation of mass and conservation of energy
principles together with the second law of thermodynamics for the design and
analysis of energy systems.

3.  It is a suitable technique for furthering the goal of more efficient energy–resource
use, for it enables the locations, types, and true magnitudes of wastes and losses to
be determined.
 It is an efficient technique revealing whether or not and by how much it is possible to
design more efficient energy systems by reducing the in efficiencies in existing
systems.
 It is a key component in obtaining a sustainable development.
INDUSTRIAL IMPORTANCE
The largest fraction of conventional power plants in the world operates on, are heat
regenerative steam power cycle. Exergy analysis of steam power plants has therefore
attracted a lot of attention over the past few decades. Most of these studies were
devoted to identifying the exergy destructions in the salient components of the power
plant, while a few others analyzed how such losses change with the plant load and
other operating conditions. However, elaborate exergy based performance analysis has
not yet been practiced widely in power stations because there is no clearly defined
standards or universally applied methodology for this. A successful implementation of
exergy based evaluation of unit performance requires formulation of performance
guarantee (PG) tests during the initial commissioning and subsequent periodic
overhauling phases. Contract compliance of individual equipment is established through
performance tests following agreed procedures. Exergy-based performance test of TG
cycle equipment can provide a more tangible commercial impact of any performance
deviation. Any deviation of exergy destruction (from the contracted value) measured in
an equipment during the PG test directly relate to the lost MWe at the generator
terminals (the useful work). Exergy-based performance test can aid maintenance
decisions also, since the potential for improvement is clearly estimated from gauging the
avoidable part of exergy destruction and the avoidable part of investments cost.
EXERGY ANALYSIS OF FARIDABAD GAS POWER
STATION
Faridabad Gas Power Station comprises of 2 gas turbine units and 1 steam turbine unit.
Steam turbine is run in a closed combined gas cycle. In this report we will carry out
exergy and energy analysis of compressor, HP turbine and LP turbine. The inputs have
been taken from control room of FGPS on 4 Feb 2012. The results will be validated
keeping in reference GT1 and ST.

4. CALCULATIONS
Observation
Point
Mass Flow Rate Temperature Pressure
1 440 516.3 72.38
2 440 206.0 5.43
3 539.7 206.9 5.10
4 539.7 93.5 0.10
Schematic of Combined Gas Cycle at
FGPS

5. 5 456 16.1 1.00
6 456 337.0 10.03
7 445 145.91 4.41
8 445 149.33 135.37
9 101 145.99 4.41
10 101 146.89 21.99
For HP Turbine exergy analysis can be brought out as,
Inlet parameters:
Temp. (T1) = 516.3 o
C, Pressure (P1) =70.97 bar, To =16.5 o
C
Enthalpy (h1) = 3448.4 kJ/kg, Entropy (s1) = 6.8417 kJ/kg o
C
Outlet Parameters:
Temp. (T2) = 206 o
C, Pressure (P2) =5.32 bar
Enthalpy (h2) = 3448.42866.4 kJ/kg, Entropy (s2) = 7.0558 kJ/kg o
C
Actual work = =122.22(3448.4-2866.4) = 71.32 MW
Maximum work = = = 78.66 MW
Exergy destruction = Maximum work – Actual work = 7.34 MW
In similar manner the exergy analysis for other components has been carried out and
tabulated in the results below.
RESULTS
Component
Actual Work, MW
a
Maximum Work,
MW
b
Exergy Destruction,
MW
b-a
HP Turbine 71.320 78.660 7.340

6. LP Turbine 85.083 95.925 10.842
Compressor -180.150 -165.870 14.280
HP BFP -2.760 -2.050 0.710
LP BFP -0.148 -0.094 0.054
CONCLUSION
Exergy analysis of crucial systems of FGPS has been conducted to identify areas with
high exergy destruction .Based on exergy calculations; exergy destruction of key areas
has been tabulated below:
0
2
4
6
8
10
12
14
16
HP Turbine LP Turbine Compressor HP BFP LP BFP
Exergy Destruction
As shown above, maximum exergy destruction has been identified in compressor
followed by LP turbine and HP turbine respectively. Thus, it is important to minimize
these exergy destructions by taking proper O&M decisions.

7. LP Turbine 85.083 95.925 10.842
Compressor -180.150 -165.870 14.280
HP BFP -2.760 -2.050 0.710
LP BFP -0.148 -0.094 0.054
CONCLUSION
Exergy analysis of crucial systems of FGPS has been conducted to identify areas with
high exergy destruction .Based on exergy calculations; exergy destruction of key areas
has been tabulated below:
0
2
4
6
8
10
12
14
16
HP Turbine LP Turbine Compressor HP BFP LP BFP
Exergy Destruction
As shown above, maximum exergy destruction has been identified in compressor
followed by LP turbine and HP turbine respectively. Thus, it is important to minimize
these exergy destructions by taking proper O&M decisions.