The formation of nitrogen oxides (NOX) in combustion systems is a significant pollutant source in the environment, and the control of NOX emissions is a world-wide concern as the utilization of fossil fuels continues to increase. In addition, the use of alternative fuels, which are typically of lower quality, tends to worsen the problem. Advances in the science of NOX reactions, mathematical modeling, and increased performance of computer systems have made comprehensive modeling of NOX formation and destruction a valuable tool to provide insights and understanding of the NOX reaction processes in combustion systems. This technology has the potential to enhance the application of various combustion techniques used to reduce NOX emissions from practical combustion systems. This paper presents a review of modeling of NOX reactions in combustion systems, with an emphasis on coal-fired systems, including current NOX control technologies, NOX reaction processes, and techniques to calculate chemical kinetics in turbulent flames. Models of NOX formation in combustion systems are reviewed. Comparisons of measured and predicted values of NOX concentrations are shown for several full-scale and laboratory-scale systems. Applications of NOX models for developing technologies, in order to reduce NOX emissions from combustion systems are also reported, including the use of over-fire air, swirling combustion air streams, fuel type, burner tilt angle, use of reburning fuels, and other methods.
Broad Academic Area of Work: Environmental Pollution Control
1 Introduction
Project Scope of work
The scope of work included modification of gas turbine burner system for reducing Nox generation in gas turbine and also maintaining turbine efficiency. The project was limited to the Power plant-2 area of Dubai Aluminium Company.
During this project a survey was jointly conducted by Dubal (Dubai Aluminium) and General Electric (Middle East) in co-ordination with Masood John Brown. The project was initiated by as per Dubal's power efficiency department request as the turbines was generating more Nox then the legal limitation.
The project was a tuff challenge for both GE and Dubal as it has to deal with design modification in an existing system. After a good hard work and brain storming exercise critical steps were evaluated to execute the project.
Main important points considered was
Nox level to be reduced as per legal requirement.
Efficiency of turbine should not change due to this modification.
Modification should provide long term reliability of turbines.
Warranty period of 5 years was recommended by DUBAL.
Dubal is having various capacities of GE gas turbines. Turbines having capacity less then 30MW doesn't need to follow legal requirement due to less generation capacity. Turbines with capacity of more then 30MW should not generate NOx more then 34 ppm in case of gas firing.
All GE gas turbines more then 100 MW was generating NOx 100 ppm. Dubal decided to reduce NOx level in GE gas turbines.
Please see next page for laboratory report.
DUBAL LABORATORY REPORT
GAS TURBINE EMISSION
Report Date: 23/03/2010
Sample Date: 21/03/2010
Sample ID
Load
Ambient Temp.
Gas Temp.
Gas colour
NO
NO2
NOX
SO2
CO
CO2
O2
NOX at 15% O2
MW
DEG C
DEG C
PPM
PPM
PPM
PPM
PPM
%
%
NO PPM
NO2 PPM
NOX PPM
GT-1
GT-2
GT-3
GT-4
GT-5
GT-6
GT-7
GT-8
GT-9
77
25
513
Clear
103
12
115
0
0
2.94
15.6
115
13
128
GT-10
78
25
514
Clear
102
5
107
0
0
2.91
15.7
116
6
121
GT-11
78
25
513
Clear
105
7
112
0
0
2.95
15.7
119
8
127
GT-12
78
26
513
Clear
104
7
110
0
0
2.95
15.6
117
8
126
GT-13
75
25
516
Clear
111
7
118
0
0
2.94
15.7
124
8
131
GT-14
90
25
495
Clear
245
12
257
0
0
3.03
15.6
278
14
192
GT-15
115
26
564
Clear
107
15
118
0.7
0
3
14.6
115
5
124
GT-16
112
25
562
Clear
108
14
119
1.1
0
3.43
14.6
116
5
125
GT-17
115
25
564
Clear
110
14
119
2.1
0
3.4
14.6
119
5
122
GT-18
113
25
565
Clear
108
15
118
1.7
0
3.4
14.7
115
5
127
GT-19
116
25
566
Clear
15
5
16
1.2
0
3.4
14.7
13
2
15
GT-20
115
26
566
Clear
15
5
16
1.2
0
3.37
14.7
13
1
17
GT-21
145
25
523
Clear
17
2
19
2.2
0
3.11
15.1
17
2
19
GT-22
145
25
525
Clear
17
2
19
2.3
0
3.14
15.1
17
2
19
GT-23
135
25
526
Clear
22
2
24
2.5
0
3.16
15.1
22
2
24
Remarks:
All Gas turbines running at the time of sampling
Nox for above 30MW units (Gas-34ppm, Liquids-73ppm)
Unit not considered due to lower generation capacity
SO2 (all fuels-175ppm)
Higher then legal requirement
CO (all fuels-1200ppm)
All legal requirements air emmisions target in ppm
Dubal Project Team
Dubal project team was including members from Project and Operation
-
PROJECT MANAGER
-
PROJECT ENGINEER
-
SUPERVISOR
DHIREN VYAS
CO-ORDINATOR
-
CONSULTANT
Figure-2 Project organizational chart
- is consultant from Dubal and he was responsible to monitor project overall progress and to give valuable suggestions and feed back to Dubal project manager.
- is responsible for execution of project. Also he was responsible to follow the guidelines and specification given by Dubal.
- - is responsible to involve in all the commissioning activities and ensuring all the activities to be carried out as per Dubal standard practice.
Dhiren Vyas - is responsible to co-ordinate and involve in all commissioning activities with GE and MJB.
Human Health and Environmental Effects of NOx Emissions from Power Generation
When emitted into the atmosphere NOx react with water and other compounds to form various acidic compounds, fine particles, and ozone. These pollutants can remain in the air for days or even years. Prevailing winds can transport them hundreds of miles, often across state and national borders. The pollutants then fall to the earth in either a wet form (rain, snow, and fog) or a dry form (gases and particles).
Impacts include
Impaired air quality
Damage to public health
Degradation of visibility
Acidification of lakes and streams
Harm to sensitive forest and coastal ecosystems
Impact on Human Health NOx emissions form fine particles in the
atmosphere
Particulate matter air pollution is emissions of NOx, which are converted into nitrate particles in the atmosphere. These particles make up a large proportion of the fine particle pollution. The health effects of Particulate matter include:
Increased incidence of premature death, primarily in the elderly and those with heart or lung disease
Aggravation of respiratory and cardiovascular illness, leading to hospitalizations and emergency room visits for children and individuals with heart or lung disease
Decreased lung function and symptomatic effects, including acute bronchitis, particularly in children and asthmatics
Chronic bronchitis
2.1.1 NOx emissions react in the atmosphere to form ozone
NOx and volatile organic compounds react in the atmosphere in the presence of sunlight to form ground-level ozone. Ground-level ozone is a major component of smog. Though naturally occurring ozone in the stratosphere provides a protective layer high above the earth, the ozone that we breathe at ground level has been linked to respiratory illness and other health problems, including:
Decreases in lung function, resulting in difficulty breathing, shortness of breath, and other symptoms
Respiratory symptoms, including bronchitis, aggravated coughing, and chest pain
Increased incidence/severity of respiratory problems (e.g. aggravation of asthma, susceptibility to respiratory infection)
Chronic inflammation and irreversible structural changes in the lungs that, with repeated exposure, can lead to premature aging of the lungs and other respiratory illness.
2.2 Impact on the Environment
NOx emissions react in the atmosphere to form acidic compounds that harm lakes and streams.
When the acidic compounds that are formed as a result of NOx emissions are deposited to the earth's surface, they can acidify lakes and streams. Acidification (low pH) and the chemical changes that result, including higher aluminium levels, make it difficult for some fish and other aquatic species to survive, grow, and reproduce.
Acid deposition harms forests and trees
Acid rain can harm forest ecosystems by directly damaging plant tissues.
In other cases, acid rain can combine with other pollutants, such as ozone, to weaken trees. Acid deposition can also affect forest ecosystems indirectly by changing the chemistry of forest soils, including the leaching of plant nutrients from soils. It can also elevate levels of aluminium in soil water, which impairs the ability of trees to use soil nutrients and can be directly toxic to plant roots.
Nitrogen deposition contributes to impaired coastal water
Quality
Excessive amounts of nitrogen in coastal waters from atmospheric deposition are thought to be a contributor to harmful algal blooms, such as red tides, that kill millions of fish each year and can be toxic to humans as well.
2.2.3 Fine particles impair visibility and increase regional haze
Fine particles formed in the atmosphere by the conversion of NOx emissions scatter light and create hazy conditions, decreasing visibility and contributing to regional haze.
3 Gas turbine combustion system
Type of combustion chamber : Fourteen multiple combustors, reverse flow
Design
Fuel nozzles : One per combustion chamber
Spark plugs : Two electrode type. Spring injected self retracting
Flame detectors : Total eight ultra-violet types
Four primary and four secondary
Combustion section
The combustion system is of the reverse-flow type with 14 combustion chambers arranged around the periphery of the compressor discharge casing. This system also includes fuel nozzle, spark plug ignition system, flame detectors and cross fire tubes. Hot gases generated from burning fuel in the combustion chambers are used to drive the turbine.
High pressure air from the compressor discharge is directed around the transition pieces and into the combustion chamber liners. This air enters the combustion zone through metering holes for proper fuel combustion and slots to cool the combustion liner. Fuel is supplied to each combustion chamber through
a nozzle designed to disperse and mix the fuel with the proper amount of combustion air.
Orientation of the combustion chambers around the periphery of the compressor is shown on figure next page. Combustion chambers are numbered counter- clock wise when viewed looking down stream and starting from the top of the machine. Spark plugs and flame detectors locations are also shown.
3.2 Combustion wrapper, Combustion chambers and cross fire tubes
Combustion wrapper:
The combustion wrapper forms a plenum in which the compressor discharge air flow is directed to the combustion chambers. Its secondary purpose is to act as a support for the combustion chamber assemblies. In turn the wrapper is supported by the compressor discharge casing and turbine shell.
Combustion chambers:
Discharge air from axial flow compressor flows into each combustion flow sleeve from the combustion wrapper. The air flow upstream along the outside of the combustion liner towards liner cap. This air enters the combustion chamber reaction zone through the fuel nozzle swirl tip, through metering holes in both the cap and liner and through combustion holes in the forward half of the liner.
The hot combustion gases from the reaction zone pass through a thermal soaking zone and then into a dilution zone where additional air is mixed with the combustion gases. Metering holes in the dilution zone allow correct amount of air to enter and cool the gases to the desired temperature. Along the length of the combustion liner and cap as shown in figure. Transition pieces direct the hot gases from the liners to the turbine nozzles. All fourteen combustion liners, flow sleeves and transition pieces are identical.
Crossfire tubes:
All fourteen combustion chambers are interconnected by means of crossfire tubes. These tubes enable flame from the fired chambers to propagate to the unfired chambers.
Nox formation and uncontrolled Nox emissions
The two primary NOx formation mechanisms in gas turbines are thermal and fuel NOx . In each case, nitrogen and oxygen present in the combustion process combine to form NOx . Thermal NOx is formed by the dissociation of atmospheric nitrogen (N ) and oxygen (O ) in the turbine combustor. When fuels containing nitrogen are combusted, this additional source of nitrogen results in fuel NOx formation. Because most turbine installations burn natural gas or light distillate oil fuels with little or no nitrogen content, thermal
NOx is the dominant source of NOx emissions. The formation rate of thermal NOx increases exponentially with increases in temperature. Because the flame temperature of oil fuel is higher than that of natural gas, NOx emissions are higher for operations using oil fuel than natural gas.
The formation of NOx
There are two mechanisms by which NOx is formed in turbine combustors:
(1) The oxidation of atmospheric nitrogen found in the combustion air and
(2) The conversion of nitrogen chemically bound in the fuel (fuel NO).
Formation of Thermal and Prompt NOx
Thermal NOx is formed by a series of chemical reactions in which oxygen and nitrogen present in the combustion air dissociate and subsequently react to form oxides of nitrogen.
The major contributing chemical reactions are known as the Zeldovich mechanism and take place in the high temperature area of the gas turbine combustor. Simply stated, the Zeldovich mechanism postulates that thermal NO formation increases exponentially with increases in temperature and linearly with
increases in residence time.
Flame temperature is dependent upon the equivalence ratio, which is the ratio of fuel burned in a flame to the amount of fuel that consumes all of the available oxygen. An equivalence ratio of 1.0 corresponds to the stoichiometric ratio and is the point at which a flame burns at its highest theoretical temperature.
Combustion is said to be fuel-lean when there is excess oxygen available (equivalence ratio <1.0). Conversely, combustion is fuel-rich if insufficient oxygen is present to burn all of the available fuel (equivalence ratio >1.0). The overall equivalence ratio for gases exiting the gas turbine combustor is less than 1.0.
Prompt NOx is formed in both fuel-rich flame zones and fuel-lean premixed combustion zones. The contribution of prompt NOx to overall NOx emissions is relatively small in conventional near-stoichiometric combustors, but this contribution increases with decreases in the equivalence ratio (fuel-lean mixtures). For this reason, prompt NOx becomes an important consideration x
for the low-NO combustor designs.
Formation of Fuel NOx
Fuel NOx (also known as organic NOx ) is formed when fuels containing nitrogen are burned. Molecular nitrogen, present as N in some natural gas, does not contribute significantly to fuel NOx formation. When these fuels are burned, the nitrogen bonds break and some of the resulting free nitrogen oxidizes to form NOx . With excess air, the degree of fuel NOx formation is primarily a function of the nitrogen content in the fuel. The fraction of fuel-bound nitrogen (FBN) converted to fuel NOx decreases with increasing nitrogen content.
Most gas turbines that operate in a continuous duty cycle are fuelled by natural gas that typically contains little or no FBN. As a result, when compared to thermal NOx, fuel NOx is not currently a major contributor to overall NOx emissions from stationary gas turbines.
Uncontrolled NOx emissions
Parameters Influencing Uncontrolled NOx Emissions
The level of NOx formation in a gas turbine, and hence the NOx emissions, is unique (by design factors) to each gas turbine model and operating mode.
The primary factors that determine the amount of NOx generated are the
Combustor design
The types of fuel being burned
Ambient conditions
Operating cycles
The power output level as a percentage of the rated full power output of the turbine.
These factors are discussed below.
Combustor Design
The design of the combustor is the most important factor influencing the formation of NOx. Thermal NOx formation is influenced primarily by flame temperature and residence time.
Design parameters controlling equivalence ratios and the introduction of cooling air into the combustor strongly influence thermal NOx formation. The extent of fuel/air mixing prior to combustion also affects NOx formation. Simultaneous mixing and combustion results in localized fuel-rich zones that yield high flame temperatures in which substantial thermal NOx production takes place. The dependence of thermal NOx formation on flame temperature and equivalence ratio is shown in Figure below.
Conversely, prompt NOx is largely insensitive to changes in temperature and pressure. Fuel NOx formation, is formed when FBN is released during combustion and oxidizes to form NOx.
Design parameters that control equivalence ratio and residence
time influence fuel NO formation.
Type of Fuel
The level of NOx emissions varies for different fuels. In the case of thermal NOx, this level increases with flame temperature. For gaseous fuels, the constituents in the gas can significantly affect NOx emissions levels. Gaseous fuel mixtures containing hydrocarbons with molecular weights higher than that of methane (e.g., ethane, propane, and butane) burn at higher flame temperatures and as a result can increase NOx emissions greater than 50 percent over NOx levels for methane gas fuel. Refinery gases and some unprocessed field gases contain significant levels of these higher molecular weight hydrocarbons. Conversely, gas fuels that contain significant inert gases, such as CO, generally produce lower NOx emissions. These inert gases serve to absorb heat during combustion, thereby lowering flame temperatures and reducing NOx emissions. Combustion of hydrogen also results in high flame temperatures, and gases with
significant hydrogen content produce relatively high NOx emissions.
NOx emissions are higher when burning distillate fuel than they are when burning natural gas. Low-Btu fuels such as coal gas burn with lower flame temperatures, which result in substantially lower thermal NOx emissions than natural gas or distillate fuel. For fuels containing FBN, the fuel NOx production increases with increasing levels of FBN.
Ambient Conditions
Ambient conditions that affect NOx formation are humidity, temperature, and pressure. Of these ambient conditions, humidity has the greatest effect on NOx formation. The energy required to heat the airborne water vapour has a quenching effect on combustion temperatures, which reduces thermal NOx formation. At low humidity levels, NOx emissions increase with increases in ambient temperature. At high humidity levels, the effect of changes in ambient
temperature on NOx formation varies. At high humidity levels and low ambient temperatures, NOx emissions increase with increasing temperature. Conversely, at high humidity levels and ambient temperatures, NOx emissions decrease with increasing temperature.
A rise in ambient pressure results in higher pressure and temperature levels entering the combustor and so Nox production levels increase with increases in ambient pressure.
Operating Cycles
Emissions from identical turbines used in simple and cogeneration cycles have similar NOx emissions levels, provided no duct burner is used in heat
recovery applications. The NO emissions are similar because NOx is formed only in the turbine combustor and remains at this level regardless of downstream
temperature reductions. A turbine operated in a regenerative cycle produces higher NOx levels, however, due to increased combustor inlet temperatures present in regenerative cycle.
Power Output Level
The power output level of a gas turbine is directly related to the firing temperature, which is directly related to flame temperature. Each gas turbine has a base-rated power level and corresponding NOX level. At power outputs below this base-rated level, the flame temperature is lower, so NOx emissions are lower. Conversely, at peak power outputs above the base rating, NOx emissions are higher due to higher flame temperature.
NOx EMISSION CONTROL TECHNIQUES
Reductions in NOx emissions can be achieved using combustion controls or flue gas treatment. Available combustion controls are water or steam injection and dry low-NO combustion designs. Selective catalytic reduction is the only available flue gas treatment.
Combustion Controls
Combustion control using water or steam lowers combustion temperatures, which reduces thermal NOx formation. Fuel NOx formation is not reduced with this technique. Water or steam, treated to quality levels comparable to boiler feed water, is injected into the combustor and acts as a heat sink to lower flame temperatures. This control technique is available for all new turbine models and can be retrofitted to most existing installations.
A system that allows treated water to be mixed with the fuel prior to injection is also available.
Dry low-NOx combustion control techniques reduce NOx emissions without injecting water or steam. Two designs lean premixed combustion and rich/quench/lean staged combustion have been developed. Lean premixed combustion designs reduce combustion temperatures, thereby reducing thermal NOx. Like wet injection, this technique is not effective in reducing fuel NOx. In a
conventional turbine combustor, the air and fuel are introduced at an approximately stoichiometric ratio and air/fuel mixing occurs simultaneously with combustion. A lean premixed combustor design premixes the fuel and air prior to combustion. Premixing results in a homogeneous air/fuel mixture, which minimizes localized fuel-rich pockets that produce elevated combustion
temperatures and higher NOx emissions. A lean air-to-fuel ratio approaching the lean flammability limit is maintained, and the excess air acts as a heat sink to lower combustion temperatures, which lowers thermal NOx formation. A pilot flame is used to maintain combustion stability in this fuel-lean environment.
The formation of both thermal NOx and fuel NOx depends upon combustion conditions, so modification of these conditions affects NOx formation. The following combustion modifications are used to control NOx emission levels:
1. Lean combustion;
2. Reduced combustor residence time;
3. Lean premixed combustion; and
4. Two-stage rich/lean combustion.
5.2 Lean Combustion and Reduced Combustor Residence Time
Process Description :
Gas turbine combustors were originally designed to operate with a primary zone equivalence ratio of approximately 1.0. (An equivalence ratio of 1.0 indicates a stoichiometric ratio of fuel and air. Equivalence ratios below 1.0 indicate fuel-lean conditions, and ratios above 1.0 indicate fuel-rich conditions.) With lean combustion, the additional excess air cools the flame, which reduces the peak flame temperature and reduces the rate of thermal NOx formation.
In all gas turbine combustor designs, the high-temperature combustion gases are cooled with dilution air to an acceptable temperature prior to entering the turbine. This dilution air rapidly cools the hot gases to temperatures below those required for thermal NOx formation. With reduced residence time combustors, dilution air is added sooner than with standard combustors. Because the combustion gases are at a high temperature for a shorter time, the amount of thermal NOx formed decreases.
Shortening the residence time of the combustion products at high temperatures may result in increased CO and HC emissions if no other changes are made in the combustor. In order to avoid increases in CO and HC emissions, combustors with reduced residence time also incorporate design changes in the air distribution ports to promote turbulence, which improves fuel/air mixing and reduces the time required for the combustion process to be completed. These designs may also incorporate fuel/air premixing chambers. Therefore, the differences between reduced residence time combustors and standard combustors are the placement of the air ports, the design of the circulation flow
patterns in the combustor, and a shorter combustor length.
Applicability :
Lean primary zone combustion and reduced residence time combustion have been applied to annular, can-annular, and silo combustor designs. Lean primary zone and reduced residence time are most applicable to low-nitrogen fuels, such as natural gas and distillate oil fuels. These modifications are not effective in reducing fuel NOx.
Factors Affecting Performance
For a given combustor, the performance of lean combustion is directly
affected by the primary zone equivalence ratio. The further the equivalence ratio is reduced below 1.0, the greater the reduction in NOx emissions. However, if the
equivalence ratio is reduced too far, CO emissions increase and flame stability problems occur.
For combustors with reduced residence time, the amount of
NOx emission reduction achieved is directly related to the decrease in residence time in the high-temperature flame zone.
Figure shows a comparison of NOx emissions from a combustor with a lean primary zone and NOx emissions from the same combustor without a lean primary zone. At the same firing temperature, NOx emissions reductions of up to 30 percent are achieved using lean primary zone combustion without increasing CO emissions.
6 RECOMMENDATION
Dubal and GE agreed to make following changes in combustion system.
6.1 Installing Lean Premixed Combustors in combustion chamber
Process Description
In a conventional combustor, the fuel and air are introduced directly into the combustion zone and fuel/air mixing and combustion take place simultaneously. Wide variations in the air-to-fuel ratio (A/F) exist, and combustion of localized fuel-rich pockets produces significant levels of NOx emissions. In a lean premixed combustor design, the air and fuel is premixed at very lean A/F's prior to introduction into the combustion zone. The excess air in the lean mixture acts as a heat sink, which lowers combustion temperatures. Premixing results in a homogeneous mixture, which minimizes localized fuel-rich zones. The resultant uniform, fuel-lean mixture results in greatly reduced NOx formation rates.
To stabilize the flame, ensure complete combustion, and minimize CO emissions, a pilot flame is incorporated into the combustor or burner design. In most designs, the relatively small amount of air and fuel supplied to this pilot flame is not premixed and the A/F is nearly stoichiometric, so the pilot flame
temperature is relatively high. As a result, NOx emissions from the pilot flame are higher than from the lean premixed combustion.
Design uses a can-annular combustor and is shown in Figure.
This is a two-stage premixed combustor: the first stage is the portion of the combustor upstream of the venturi section and includes the six primary fuel nozzles; the second stage is the balance of the combustor and includes the single secondary fuel nozzle.
6.2 Changes in operating mode
Following changes made in the operating modes to improve NOx emmission. For ignition, warm-up, and acceleration to approximately 100 percent load, different functions introduced.
The Dry low NOx combustion system operates in four distinct modes during natural gas fuel operation:
1) Primary Mode:
Operating in Ignition, acceleration and operation to 30% load (Fuel to first stage)
2) Lean- Lean Mode:
30% load to approximately 50% load (Fuel to both stages and fuel in both stages.
3) Secondary (Transfer) Mode:
Staging at 70% load (fuel to second stage only)
4) Premixed Mode:
70% to 100% load (fuel to both stages, flame in second stage only)
Flame is present only in the first stage, and the equivalence ratio is kept as low as stable combustion will permit. With increasing load, fuel is introduced into the secondary stage, and combustion takes place in both stages. Again, the equivalence ratio is kept as low as possible in both stages to minimize NOx
emissions. When the load reaches approximately 40 percent, fuel is cut off to the first stage and the flame in this stage is extinguished. The venturi ensures the flame in the second stage cannot propagate upstream to the first stage. When the first stage flame is extinguished (as verified by internal flame detectors), fuel is again introduced into the first stage, which becomes a premixing zone to deliver a lean, unburned, uniform mixture to the second stage. The second stage acts as the complete combustor in this configuration.
7 LAB REPORT
Improvement in NOx emission after modification is given below in DUBAL LABORATORY report.
DUBAL LABORATORY REPORT
GAS TURBINE EMISSION
Report Date: 20/09/2010
Sample Date: 15/09/2010
Sample ID
Load
Ambient Temp.
Gas Temp.
Gas colour
NO
NO2
NOX
SO2
CO
CO2
O2
NOX at 15% O2
MW
DEG C
DEG C
PPM
PPM
PPM
PPM
PPM
%
%
NO PPM
NO2 PPM
NOX PPM
GT-1
GT-2
GT-3
GT-4
GT-5
GT-6
GT-7
GT-8
GT-9
77
25
513
Clear
103
12
115
0
0
2.94
15.6
115
13
128
GT-10
78
25
514
Clear
102
5
107
0
0
2.91
15.7
116
6
121
GT-11
78
25
513
Clear
105
7
112
0
0
2.95
15.7
119
8
127
GT-12
78
26
513
Clear
104
7
110
0
0
2.95
15.6
117
8
126
GT-13
75
25
516
Clear
111
7
118
0
0
2.94
15.7
124
8
131
GT-14
90
25
495
Clear
245
12
257
0
0
3.03
15.6
278
14
192
GT-15
115
26
564
Clear
14
15
16
0.7
0
3
14.6
13
5
15
GT-16
112
25
562
Clear
10
14
12
1.1
0
3.43
14.6
9
5
11
GT-17
115
25
564
Clear
17
14
18
2.1
0
3.4
14.6
16
5
17
GT-18
113
25
565
Clear
15
15
16
1.7
0
3.4
14.7
14
5
15
GT-19
116
25
566
Clear
15
5
16
1.2
0
3.4
14.7
13
2
15
GT-20
115
26
566
Clear
15
5
16
1.2
0
3.37
14.7
13
1
17
GT-21
145
25
523
Clear
17
2
19
2.2
0
3.11
15.1
17
2
19
GT-22
145
25
525
Clear
17
2
19
2.3
0
3.14
15.1
17
2
19
GT-23
135
25
526
Clear
22
2
24
2.5
0
3.16
15.1
22
2
24
Remarks:
All Gas turbines running at the time of sampling
Nox emission after DLN modification
Nox for above 30MW units (Gas-34ppm, Liquids-73ppm)
Unit not considered due to lower generation capacity
SO2 (all fuels-175ppm)
Higher then legal requirement
CO (all fuels-1200ppm)
All legal requirements air emmisions target in ppm
