Mustapha Chaker

Inlet Fogging of Gas Turbine Engines—Part I: Fog Droplet Thermodynamics, Heat Transfer, and Practical Considerations

The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade yet not a single technical paper treating the physics and engineering of the fogging process, droplet size measurement, droplet kinetics, or the duct behavior of droplets, from a gas turbine perspective, is available. This paper provides the results of extensive experimental and theoretical studies conducted over several years coupled with practical aspects learned in the implementation of nearly 500 inlet fogging systems on gas turbines ranging in power from 5 to 250 MW. Part A of the paper covers the underlying theory of droplet thermodynamics and heat transfer, and provides several practical pointers relating to the implementation and application of inlet fogging to gas turbine engines.

Inlet fogging of gas turbine engines. Part II: Fog droplet sizing analysis, nozzle types, measurement, and testing

The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade yet not a single technical paper treating the physics and engineering of the fogging process, droplet size measurement, droplet kinetics, or the duct behavior of droplets, from a gas turbine perspective, is available. This paper provides the results of extensive experimental and theoretical studies conducted over several years, coupled with practical aspects learned in the implementation of nearly 500 inlet fogging systems on gas turbines ranging in power from 5 to 250 MW. Part B of the paper treats the practical aspects of fog nozzle droplet sizing, measurement and testing presenting the information from a gas turbine fogging perspective. This paper describes the different measurement techniques available, covers design aspects of nozzles, provides experimental data on different nozzles and provides recommendations for a standardized nozzle testing method for gas turbine inlet air fogging.

Gas Turbine Fogging Technology: A State-Of-The-Art Review, Part I: Inlet Evaporative Fogging- Analytical And Experimental Aspects

Ambient temperature strongly influences gas turbine power output causing a reduction of around 0.50% to 0.90% for every 1°C of temperature rise. There is also a significant increase in the gas turbine heat rate as the ambient temperature rises, resulting in an increased operating cost. As the increase in power demand is usually coincident with high ambient temperature, power augmentation during the hot part of the day becomes important for independent power producers, cogenerators, and electric utilities. Evaporative and overspray fogging are simple, proven, and cost effective approaches for recovering lost gas turbine performance. A comprehensive review of the current understanding of the analytical, experimental, and practical aspects including climatic and psychrometric aspects of high-pressure inlet evaporative fogging technology is provided. A discussion of analytical and experimental results relating to droplets dynamics, factors affecting droplets size, and inlet duct configuration effects on inlet evaporative fogging is covered in this paper. Characteristics of commonly used fogging nozzles are also described and experimental findings presented.

Inlet Fogging of Gas Turbine Engines: Climatic Analysis of Gas Turbine Evaporative Cooling Potential of International Locations

Inlet fogging of gas turbine engines has attained considerable popularity due to the ease of installation and the relatively low first cost compared to other inlet cooling methods. With increasing demand for power and with shortages envisioned especially during the peak load times during the summers, there is a need to boost gas turbine power. There is a sizable evaporative cooling potential throughout the world when the climatic data is evaluated based on an analysis of coincident wet bulb and dry bulb information. These data are not readily available to plant users. In this paper, a detailed climatic analysis is made of 106 major locations over the world to provide the hours of cooling that can be obtained by direct evaporative cooling. This data will allow gas turbine operators to easily make an assessment of the economics of evaporative fogging. The paper also covers an introduction to direct evaporative cooling and the methodology and data analysis used to derive the cooling potential. Simulation runs have been made for gas turbine simple cycles showing effects of fogging for a GE Frame 7EA and a GE Frame 9FA Gas turbine for 60 and 50 Hz applications.

Gas Turbine Performance Deterioration.

With privatization and intense competition in the utility and petrochemical industry, there is a strong incentive for gas turbine operators to minimize and control performance deterioration, as this directly affects profitability. The area of gas turbine recoverable and nonrecoverable performance deterioration is comprehensively treated in this paper. Deterioration mechanisms including compressor and turbine fouling, erosion, increased clearances, and seal distress are covered along with their manifestations, rules of thumb, and mitigation approaches. Permanent deterioration is also covered. Because of the importance of compressor fouling, gas turbine inlet filtration, fouling mechanisms, and compressor washing are covered in detail. Approaches for the performance monitoring of steady-state and transient behavior are presented along with simulations of common deterioration modes of gas turbine combined cycles. As several gas turbines are used in cogeneration and combined cycles, a brief discussion of heat recovery steam generator performance monitoring is made.

Gas Turbine Fogging Technology: A State-Of-The-Art Review, Part II: Overspray Fogging - Analytical And Experimental Aspects

The strong influence of ambient temperature on the output and heat rate on a gas turbine has popularized the application of inlet fogging and overspray for power augmentation. One of the main advantages of overspray fogging is that it enhances power output as a result of decrease in compression work associated with the continuous evaporation of water within the compressor due to fog intercooling. A comprehensive review on the current understanding of the analytical and experimental aspects of overspray fogging technology as applied to gas turbines is presented in this paper.

Inlet Fogging of Gas Turbine Engines Detailed Climatic Analysis of Gas Turbine Evaporation Cooling Potential in the USA

Inlet fogging of gas turbine engines has attained considerable popularity due to the ease of installation and the relatively low first cost compared to other inlet cooling methods. With increasing demand for power and with shortage envisioned especially during the peak load times during the summers, there is a need to boost gas turbine power. There is a sizable evaporative cooling potential throughout the world when the climatic data is evaluated based on an analysis of coincident wet bulb and dry bulk information. These data are not readily available to plant users. In this paper a detailed climatic analysis is made of 122 locations in the U.S. to provide the hours of cooling that can be obtained by direct evaporative cooling. These data will allow gas turbine operators to easily make an assessment of the economics of evaporative cooling. The paper also covers an introduction to direct evaporative cooling and the methodology and data analysis used to derive the cooling potential in different regions of the U.S. Simulation runs have been made for gas turbine simple cycles using a reference plant based on a GE Frame 7111EA gas turbine at the 122 locations studied in the U.S. to provide a feel for the sensitivity of operation with inlet fogging.

Inlet Fogging of Gas Turbine Engines—Part III: Fog Behavior in Inlet Ducts, Computational Fluid Dynamics Analysis, and Wind Tunnel Experiments

The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade yet not a single technical paper treating the physics and engineering of the fogging process, droplet size measurement, droplet kinetics, or the duct behavior of droplets, from a gas turbine perspective, is available. This paper along with Parts I and II provides the results of extensive experimental and theoretical studies conducted over several years coupled with practical aspects learned in the implementation of nearly 500 inlet fogging systems on gas turbines ranging in power from 5 to 250 MW. In Part III of this paper, the complex behavior of fog droplets in the inlet duct is addressed and experimental results from several wind tunnel studies are covered.

Inlet Fogging of Gas Turbine Engines: Part C — Fog Behavior in Inlet Ducts, CFD Analysis and Wind Tunnel Experiments

The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade yet not a single technical paper treating the physics and engineering of the fogging process, droplet size measurement, droplet kinetics, or the duct behavior of droplets, from a gas turbine perspective, is available. This paper along with Parts A and B provides the results of extensive experimental and theoretical studies conducted over several years coupled with practical aspects learned in the implementation of nearly 500 inlet fogging systems on gas turbines ranging in power from 5 to 250 MW. In part C of this paper, the complex behavior of fog droplets in the inlet duct is addressed and experimental results from several wind tunnel studies are covered.Copyright

The Fouling of Axial Flow Compressors: Causes, Effects, Susceptibility and Sensitivity

Increased fuel costs have created a strong incentive for gas turbine operators to understand, minimize and control performance deterioration. The most prevalent deterioration problem faced by gas turbine operators is compressor fouling. Fouling causes a drop in airflow, pressure ratio and compressor efficiency, resulting in a “re-matching” of the gas turbine and compressor and a drop in power output and thermal efficiency. This paper addresses the causes and effects of fouling and provides a comprehensive treatment of the impact of salient gas turbine design parameters on the susceptibility and sensitivity to compressor fouling. Simulation analysis of ninety two (92) gas turbines of ranging from a few kW to large engines rated at greater than 300 MW has been conducted. It is hoped that this paper will provide practical information to gas turbine operators.Copyright