An Evaluation of the Effects of Water Injection on Compressor Performance

2003 ◽  
Author(s):  
A. J. White ◽  
A. J. Meacock
Keyword(s):  
Gas Turbines ◽  
Evaporative Cooling ◽  
Water Injection ◽  
Compression Process ◽  
Compressor Inlet ◽  
Design Behaviour ◽  
Industrial Gas Turbines ◽  
Compressor Performance ◽  
Compressor Work ◽  
The Impact

The injection of water droplets into compressor inlet ducting is now commonly used as a means of boosting the output from industrial gas turbines. The chief mechanisms responsible for the increase in power are the reduction in compressor work per unit flow and the increase in mass flow rate, both of which are achieved by evaporative cooling upstream of and within the compressor. This paper examines the impact of such evaporative processes on compressor operation, focussing particular attention on cases with substantial over-spray — i.e., for which significant evaporation takes place within the compressor itself, rather than in the inlet. A simple numerical method is described for the computation of wet compression processes, based on a combination of droplet evaporation and mean-line calculations. The method is applied to a “generic” compressor geometry in order to investigate the nature of the off-design behaviour that results from evaporative cooling. Consideration is also given to the efficiency of the compression process, the implications for choking and stall, and the magnitude of the thermodynamic loss resulting from irreversible phase change.

An Evaluation of the Effects of Water Injection on Compressor Performance

2004 ◽  
Vol 126 (4) ◽  
pp. 748-754 ◽  
Author(s):  
A. J. White ◽  
A. J. Meacock
Keyword(s):  
Gas Turbines ◽  
Evaporative Cooling ◽  
Water Injection ◽  
Droplet Evaporation ◽  
Compression Process ◽  
Compressor Inlet ◽  
Industrial Gas Turbines ◽  
Compressor Performance ◽  
Compressor Work ◽  
The Impact

The injection of water droplets into compressor inlet ducting is now commonly used as a means of boosting the output from industrial gas turbines. The chief mechanisms responsible for the increase in power are the reduction in compressor work per unit flow and the increase in mass flow rate, both of which are achieved by evaporative cooling upstream of and within the compressor. This paper examines the impact of such evaporative processes on compressor operation, focussing particular attention on cases with substantial overspray—i.e., for which significant evaporation takes place within the compressor itself, rather than in the inlet. A simple numerical method is described for the computation of wet compression processes, based on a combination of droplet evaporation and mean-line calculations. The method is applied to a “generic” compressor geometry in order to investigate the nature of the off-design behavior that results from evaporative cooling. Consideration is also given to the efficiency of the compression process, the implications for choking and stall, and the magnitude of the thermodynamic loss resulting from irreversible phase change.

Increasing Diagnostic Effectiveness by Inclusion of Fuel Composition and Water Injection Effects

2002 ◽  
Author(s):  
K. Mathioudakis ◽  
N. Aretakis ◽  
A. Tsalavoutas
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Water Injection ◽  
Diagnostic Technique ◽  
Diagnostic Methods ◽  
Working Fluid ◽  
Fluid Properties ◽  
Industrial Gas Turbines ◽  
The Impact ◽  
Engine Condition

The paper presents an analysis of the effect of changing the fuel on the performance of industrial gas turbines and examines the impact of such a change on methods used for engine condition assessment and fault diagnostics. A similar analysis is presented for the effects of water injection in the combustion chamber (which is usually done for reducing NOx emissions). First, the way of incorporating the effect of fuel changes and water injection into a computer model of gas turbine performance is described. The approach employed is based on the change of (a) working fluid properties, (b) turbomachinery components performance. The model is then used to derive parameters indicative of the “health” of a gas turbine and thus diagnose the presence of deterioration or faults. The impact of ignoring the presence of an altered fuel or injected water is shown to be of a magnitude that would render a diagnostic technique that does not incorporate these effects ineffective. On the other hand, employing the appropriate physical modeling makes the diagnostic methods robust and insensitive to such changes, being thus able to provide useful diagnostic information continuously during the use of a gas turbine.

Gas Turbine Compressor Performance Characteristics During Wet Compression: Influence of Polydisperse Spray

2009 ◽  
Author(s):  
Rakesh K. Bhargava ◽  
Michele Bianchi ◽  
Mustapha Chaker ◽  
Francesco Melino ◽  
Antonio Peretto ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Performance Characteristics ◽  
Analytical Models ◽  
Lower Amount ◽  
Compression Process ◽  
Surge Margin ◽  
Compressor Performance ◽  
Wet Compression ◽  
The Impact

The available literature shows that there exists a lack of understanding about the impact of wet compression, involving two-phase flow, on the physics of flow in the compressor stages of a gas turbine engine. In recent years, analytical models have been proposed which provide effects of wet compression on the overall compressor performance and in few studies on the stage-by-stage performance. In spite of the fact that the wet compression technology for power augmentation has been commercially implemented on numerous gas turbines from all the major gas turbine manufacturers, many issues such as, effects of polydisperse spray, droplets dynamics, influence on the performance characteristics of individual stages, stage and overall surge margin, etc., remain not completely understood. This investigation clearly shows importance of considering effects of polydisperse spray on the overall and stage-by-stage compressor performance characteristics. The presented results show that for a given droplets distribution and ambient condition, later stages of a compressor are prone to reduced surge margin under wet compression process due to redistribution of stage loading. Moreover, the study shows that smaller distributions allow the achievement of higher performance, but the compressor surge is reached with a lower amount of injected water.

Wet Compression Analysis Including Velocity Slip Effects

2010 ◽  
Author(s):  
A. J. White ◽  
A. J. Meacock
Keyword(s):  
Gas Turbines ◽  
Velocity Slip ◽  
Design Flow ◽  
Compression Process ◽  
Relaxation Effects ◽  
Slip Effects ◽  
Industrial Gas Turbines ◽  
Wet Compression ◽  
Dry Climates ◽  
The Impact

Injection of water droplets into industrial gas turbines in order to boost power output is now common practice. The intention is usually to saturate and cool the intake air, especially in hot and dry climates, but in many cases droplets carry over into the compressor and continue to evaporate. Evaporation within the compressor itself (often referred to as “overspray”) is also central to several advanced wet cycles, including the Moist Air Turbine (MAT) and the so-called TOPHAT cycle. The resulting wet compression process affords a number of thermodynamic advantages, such as reduced compression work, and increased mass flow rate and specific heat capacity of the turbine flow. Against these benefits, many of the compressor stages will operate at significantly off-design flow angles, thereby compromising aerodynamic performance. The current paper describes wet compression calculations including velocity slip and many of the associated phenomena (e.g., blade deposition and film evaporation). The calculations also allow for a poly-dispersion of droplet sizes and droplet temperature relaxation effects (i.e., the full droplet energy equation is solved rather than assuming that droplets adopt the wet-bulb temperature). The latter is important for sprays produced by “flashing” since the resulting droplets are initially much hotter than the surrounding gas. The method has been applied to a “generic” twelve stage compressor to ascertain to the impact slip effects have on the wet compression process.

The Effect of Water Injection for Emissions Control on Industrial Gas Turbine Combustors

1984 ◽  
Author(s):  
R. J. Antos ◽  
W. C. Emmerling
Keyword(s):  
Gas Turbines ◽  
Mechanical Design ◽  
Water Injection ◽  
Combustion Process ◽  
Liquid Fuels ◽  
Nox Emissions ◽  
Design Features ◽  
Industrial Gas Turbines ◽  
Comprehensive Test ◽  
Industrial Gas Turbine

One common method of reducing the NOx emissions from industrial gas turbines is to inject water into the combustion process. The amount of water injected depends on the emissions rules that apply to a particular unit. Westinghouse W501B industrial gas turbines have been operated at water injection levels required to meet EPA NOx emissions regulations. They also have been operated at higher injection levels required to meet stricter California regulations. Operation at the lower rates of water did not affect combustor inspection and/or repair intervals. Operation on liquid fuels with high rates of water also did not result in premature distress. However, operation on gas fuel at high rates of water did cause premature distress in the combustors. To evaluate this phenomenon, a comprehensive test program was conducted; it demonstrated that the distress is the result of the temperature patterns in the combustor caused by the high rates of water. The test also indicated that there is no significant change in dynamic response levels in the combustor. This paper presents the test results, and the design features selected to substantially improve combustor wall temperature when operating on gas fuels, with the high rates of water injection required to meet California applications. Mechanical design features that improve combustor resistance to water injection-induced thermal gradients also are presented.

scholarly journals Industrial Gas Turbine Performance: Compressor Fouling and On-Line Washing

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Uyioghosa Igie ◽  
Pericles Pilidis ◽  
Dimitrios Fouflias ◽  
Kenneth Ramsden ◽  
Panagiotis Laskaridis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Operating Conditions ◽  
Compressor Cascade ◽  
Compressor Blades ◽  
Turbine Performance ◽  
Industrial Gas Turbines ◽  
On Line ◽  
The Impact

Industrial gas turbines are susceptible to compressor fouling, which is the deposition and accretion of airborne particles or contaminants on the compressor blades. This paper demonstrates the blade aerodynamic effects of fouling through experimental compressor cascade tests and the accompanied engine performance degradation using turbomatch, an in-house gas turbine performance software. Similarly, on-line compressor washing is implemented taking into account typical operating conditions comparable with industry high pressure washing. The fouling study shows the changes in the individual stage maps of the compressor in this condition, the impact of degradation during part-load, influence of control variables, and the identification of key parameters to ascertain fouling levels. Applying demineralized water for 10 min, with a liquid-to-air ratio of 0.2%, the aerodynamic performance of the blade is shown to improve, however most of the cleaning effect occurred in the first 5 min. The most effectively washed part of the blade was the pressure side, in which most of the particles deposited during the accelerated fouling. The simulation of fouled and washed engine conditions indicates 30% recovery of the lost power due to washing.

Power Augmentation Approaches for Mechanical Drive Turbines

2013 ◽  
Author(s):  
Cyrus B. Meher-Homji ◽  
Mustapha A. Chaker
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Oil And Gas ◽  
Water Injection ◽  
Inlet Temperature ◽  
Process Industries ◽  
Ambient Temperatures ◽  
Compressor Inlet ◽  
Cooling Technology ◽  
Selection Of

Mechanical drive gas turbine can benefit significantly by power augmentation. In the oil and gas, petrochemical and process industries, the reduction in output of mechanical drive gas turbines curtails plant output or throughput. Gas turbines exhibit a drop in power output with an increase in air compressor inlet temperature of the order of 0.7% / °C for heavy duty gas turbines and approximately 1% / °C for aeroderivative turbines. Power augmentation by inlet cooling is an attractive means to minimize production swings. Designing gas turbine driven refrigeration compressors for high ambient temperature swings is also a design challenge due to power limitations at high ambient temperatures and high refrigerant condensing pressures. This paper will address a range of gas turbine inlet cooling techniques, and provide a technical perspective of different inlet cooling approaches. Technical approaches including inlet evaporative cooling, inlet fogging, wet compression, inlet mechanical and absorption chilling are covered. Other approaches such as water injection are briefly discussed. The judicious selection of the dry bulb temperature and coincident relative humidity for the design and selection of the cooling technology is discussed.

Evaluation of Advanced Combustors for Dry NOx Suppression With Nitrogen Bearing Fuels in Utility and Industrial Gas Turbines

1982 ◽  
Vol 104 (2) ◽  
pp. 429-438 ◽  
Author(s):  
M. B. Cutrone ◽  
M. B. Hilt ◽  
A. Goyal ◽  
E. E. Ekstedt ◽  
J. Notardonato
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Water Injection ◽  
Operating Conditions ◽  
Department Of Energy ◽  
Technical Program ◽  
Wide Range ◽  
Industrial Gas Turbines ◽  
Low Levels

The work described in this paper is part of the DOE/LeRC Advanced Conversion-Technology Project (ACT). The program is a multiple contract effort with funding provided by the Department of Energy, and technical program management provided by NASA LeRC. Combustion tests are in progress to evaluate the potential of seven advanced combustor concepts for achieving low NOx emissions for utility gas turbine engines without the use of water injection. Emphasis was on the development of the required combustor aerothermodynamic features for burning high nitrogen fuels. Testing was conducted over a wide range of operating conditions for a 12:1 pressure ratio heavy-duty gas turbine. Combustors were evaluated with distillate fuel, SRC-II coal-derived fuel, residual fuel, and blends. Test results indicate that low levels of NOx and fuel-bound nitrogen conversion can be achieved with rich-lean combustors for fuels with high fuel-bound nitrogen. In addition, ultra-low levels of NOx can be achieved with lean-lean combustors for fuels with low fuel-bound nitrogen.

Wet Compression Effects on Axial Compressor Performance Using Pitch-Line Models

2010 ◽  
Author(s):  
Arathi K. Gopinath ◽  
Giridhar Jothiprasad ◽  
Trevor Wood ◽  
Le Tran
Keyword(s):  
Axial Compressor ◽  
Water Evaporation ◽  
Performance Predictions ◽  
Blade Row ◽  
Compressor Inlet ◽  
Droplet Sizes ◽  
Compressor Performance ◽  
Wet Compression ◽  
Compression Effects ◽  
The Impact

The impact of wet compression technology on compressor performance is studied using a coupled water-evaporation-pitch-line numerical model. The model uses an iterative approach to compute the modified flow conditions at blade-row stations due to inter-stage evaporation of water droplets introduced at the compressor inlet. The evaporation rate predicted by the model is compared with experimental data for stationary droplets in a duct. Performance predictions are compared with data for a GE-proprietary compressor. Study of various water droplet sizes and various water-to-air mass ratios is discussed.

Uncertainty Reduction in Gas Turbine Performance Diagnostics by Accounting for Humidity Effects

2001 ◽  
Author(s):  
K. Mathioudakis ◽  
A. Tsalavoutas
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Ambient Conditions ◽  
Ambient Temperatures ◽  
Turbine Performance ◽  
Industrial Gas Turbines ◽  
Industrial Gas Turbine ◽  
The Impact ◽  
Performance Diagnostics ◽  
Health Parameters

The paper presents an analysis of the effect of ambient humidity on the performance of industrial gas turbines and examines the impact of humidity on methods used for engine condition assessment and fault diagnostics. First, the way of incorporating the effect of humidity into a computer model of gas turbine performance is described. The model is then used to derive parameters indicative of the “health” of a gas turbine and thus diagnose the presence of deterioration or faults. The impact of humidity magnitude on the values of these health parameters is studied and the uncertainty introduced, if humidity is not taken into account, is assessed. It is shown that the magnitude of the effect of humidity depends on ambient conditions and is more severe for higher ambient temperatures. Data from an industrial gas turbine are presented to demonstrate these effects and to show that if humidity is appropriately taken into account, the uncertainty in the estimation of health parameters is reduced

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