Effect of Water Temperature on the Performance of Gas Turbine Inlet Air-Fogging Systems

Author(s):  
Mustapha A. Chaker ◽  
Cyrus B. Meher-Homji

With more than 1000 fogging systems installed worldwide on a wide range of gas turbines of different types, gas turbine inlet air fogging systems have become a well-established technology used to increase gas turbines power output. The major benefit of spraying fog droplets in the inlet airflow of the gas turbines is to increase the density of the air entering the gas turbine by evaporative cooling in the inlet air stream. Significant amount of research has been carried out to improve the efficiency of fogging systems. However, the effect of water temperature on the overall efficiency of a fogging system has yet to be addressed. In this paper, a detailed analysis of this effect will be presented, both from an experimental and a theoretical view point. Due to the small size of the droplets used in this application, the temperature of the droplet converges quickly to the wet bulb temperature, regardless of the initial water temperature. The rapidity at which this convergence occurs depends on the initial droplet size, the water temperature, the air mass flow to mass of injected water ratio, and the ambient psychrometric conditions of the surrounding air. The present study was carried out using water temperatures between 1 °C and 60 °C. Results showed that the water temperature has no significant effect on the droplet size. However, within the range of droplet sizes atomized from nozzles installed in the fogging system, using cold water provides a marginal benefit on the cooling efficiency; using hot water, on the other hand, slightly increases the evaporation efficiency.

Author(s):  
Mustapha A. Chaker

Application of inlet air fogging to gas turbine engines for power augmentation, has become common practice, with more than a 1000 installations worldwide including a large number of advanced gas turbines. In this paper an experimental investigation and empirical analysis of key operating parameters on the performance of impaction pin nozzles will be investigated. To this date no such correlation is available for impaction pin nozzles, which are currently used in about 75% of this type of applications. The correlations are developed from a series of experiments conducted in a wind tunnel equipped with the Malvern Spraytec droplet size measurement system. The conducted analysis covered a wide range of the relevant parameters. Mainly the water flow rate from the nozzle orifice was (0.00126 1.s−1 to 0.00063 1.s−1: 0.02 gpm to 0.1 gpm), the operating pressure was (34.5 bars to 204.1 bars: 500 psi to 3000 psi), the airflow velocity was (1.5 m.s−1 to 15.2 m.s−1: 295 fpm to 3000 fpm), the distance between the nozzle orifice and the location of measurement was (0.0127m to 0.508 m: 0.5” to 20”). Other parameters such as the plume spray one angle and the surrounding ambient psychrometric conditions, which may affect the droplet size for impaction pin nozzles is also discussed.


1980 ◽  
Author(s):  
R. L. Graves

The difficulties encountered in past and present efforts to operate direct coal-fired gas turbines are substantial. Hence the development effort required to assure a reliable, high-temperature pressurized fluidized bed (PFBC) combined cycle may be very expensive and time consuming. It is, therefore, important that the benefit of achieving high-temperature operation, which is primarily increased efficiency, be clearly understood at the outset of such a development program. This study characterizes the effects of PFBC temperature and pressure on plant efficiency over a wide range of values. There is an approximate three percentage point advantage by operating at a gas turbine inlet temperature of 870 C (1600 F) instead of 538 C (1000 F). Optimum pressure varies with the gas turbine inlet temperature, but ranges from 0.4–1.0 MPa (4–10 atm). An alternate PFBC cycle offering high efficiency at a peak temperature of about 650 C (1200 F) is also discussed.


Author(s):  
P. A. Phillips ◽  
Peter Spear

After briefly summarizing worldwide automotive gas turbine activity, the paper analyses the power plant requirements of a wide range of vehicle applications in order to formulate the design criteria for acceptable vehicle gas turbines. Ample data are available on the thermodynamic merits of various gas turbine cycles; however, the low cost of its piston engine competitor tends to eliminate all but the simplest cycles from vehicle gas turbine considerations. In order to improve the part load fuel economy, some complexity is inevitable, but this is limited to the addition of a glass ceramic regenerator in the 150 b.h.p. engine which is described in some detail. The alternative further complications necessary to achieve satisfactory vehicle response at various power/weight ratios are examined. Further improvement in engine performance will come by increasing the maximum cycle temperature. This can be achieved at lower cost by the extension of the use of ceramics. The paper is intended to stimulate the design application of the gas turbine engine.


Author(s):  
Dominik Ebi ◽  
Peter Jansohn

Abstract Operating stationary gas turbines on hydrogen-rich fuels offers a pathway to significantly reduce greenhouse gas emissions in the power generation sector. A key challenge in the design of lean-premixed burners, which are flexible in terms of the amount of hydrogen in the fuel across a wide range and still adhere to the required emissions levels, is to prevent flame flashback. However, systematic investigations on flashback at gas turbine relevant conditions to support combustor development are sparse. The current work addresses the need for an improved understanding with an experimental study on boundary layer flashback in a generic swirl burner up to 7.5 bar and 300° C preheat temperature. Methane-hydrogen-air flames with 50 to 85% hydrogen by volume were investigated. High-speed imaging was applied to reveal the flame propagation pathway during flashback events. Flashback limits are reported in terms of the equivalence ratio for a given pressure, preheat temperature, bulk flow velocity and hydrogen content. The wall temperature of the center body along which the flame propagated during flashback events has been controlled by an oil heating/cooling system. This way, the effect any of the control parameters, e.g. pressure, had on the flashback limit was de-coupled from the otherwise inherently associated change in heat load on the wall and thus change in wall temperature. The results show that the preheat temperature has a weaker effect on the flashback propensity than expected. Increasing the pressure from atmospheric conditions to 2.5 bar strongly increases the flashback risk, but hardly affects the flashback limit beyond 2.5 bar.


Author(s):  
Daniel E. Caguiat

The Naval Surface Warfare Center, Carderock Division (NSWCCD) Gas Turbine Emerging Technologies Code 9334 was tasked by NSWCCD Shipboard Energy Office Code 859 to research and evaluate fouling resistant compressor coatings for Rolls Royce Allison 501-K Series gas turbines. The objective of these tests was to investigate the feasibility of reducing the rate of compressor fouling degradation and associated rate of specific fuel consumption (SFC) increase through the application of anti-fouling coatings. Code 9334 conducted a market investigation and selected coatings that best fit the test objective. The coatings selected were Sermalon for compressor stages 1 and 2 and Sermaflow S4000 for the remaining 12 compressor stages. Both coatings are manufactured by Sermatech International, are intended to substantially decrease blade surface roughness, have inert top layers, and contain an anti-corrosive aluminum-ceramic base coat. Sermalon contains a Polytetrafluoroethylene (PTFE) topcoat, a substance similar to Teflon, for added fouling resistance. Tests were conducted at the Philadelphia Land Based Engineering Site (LBES). Testing was first performed on the existing LBES 501-K17 gas turbine, which had a non-coated compressor. The compressor was then replaced by a coated compressor and the test was repeated. The test plan consisted of injecting a known amount of salt solution into the gas turbine inlet while gathering compressor performance degradation and fuel economy data for 0, 500, 1000, and 1250 KW generator load levels. This method facilitated a direct comparison of compressor degradation trends for the coated and non-coated compressors operating with the same turbine section, thereby reducing the number of variables involved. The collected data for turbine inlet, temperature, compressor efficiency, and fuel consumption were plotted as a percentage of the baseline conditions for each compressor. The results of each plot show a decrease in the rates of compressor degradation and SFC increase for the coated compressor compared to the non-coated compressor. Overall test results show that it is feasible to utilize anti-fouling compressor coatings to reduce the rate of specific fuel consumption increase associated with compressor performance degradation.


Author(s):  
Terry B. Sullivan ◽  
Michael Giampetro

This paper provides comprehensive methodology on testing inlet chiller systems that are used for Gas Turbine Inlet Air Conditioning. It will serve as a guiding document for the Inlet Chiller Project Team formed by PTC 51, “Combustion Turbine Inlet Air Conditioning Equipment” for use in scripting that code’s section on Inlet Chiller Performance Testing. This paper shows the conceptual similarities that can be drawn between inlet chiller and overall plant performance testing, as well as detailing the pertinent test scopes and boundaries, identifying expected test objectives, and listing the applicable test boundary parameters to be used for correction. Addressing an industry need, this paper also offers guidance on testing these components / systems at conditions different than design. Current equipment code committees, such as ASME PTC 22 on Gas Turbines, and ASME PTC 46 on Overall Plant Performance Testing, have concluded that inlet air conditioning equipment must be out of service while testing the major plant equipment. This would require the inlet chilling system to be tested separately. This requirement dictates that a technically-sound method of inlet chiller testing be codified in a timely manner.


Author(s):  
G. E. Parker

Controls for small lightweight gas turbines present some unique design problems. The requirements for small size, light weight, ability to rotate at high speeds to save reduction gearing, and low production cost conflict with the requirements for reasonably accurate control of very small fuel flows and the scheduling of a wide range of hydrocarbon fuels over a wide range of ambient temperatures. This paper discusses in some detail the design of such a control and the satisfactory results obtained.


Author(s):  
Joseph C. Mollendorf ◽  
David R. Pendergast

Underwater workers, sport and military divers, are exposed to thermal stress since most of the waters of the world are below or above what is thermally neutral. Although divers wear insulation suits for passive thermal protection they are inadequate. Active heating is currently accomplished by resistive heating and open-flow tubes delivering hot water; however, these methods are problematic. The challenge of this project was to design, build and test an active diver thermal protection system (DTPS) to be used with wet suit insulation that is effective, user-friendly, reliable, and that could be used by a free-swimming diver. The DTPS has a minimum number of moving parts, is low maintenance, has no unsafe or toxic working fluid and uses no consumables except a safe, high density, modular electrical power source. A portable and swimmable, self-contained, electrically powered unit (DTPS) has been designed, built, and tested that produces and circulates thermally conditioned water in a closed-loop through a zoned tube suit worn by a diver under a wetsuit to maintain skin and body core temperatures within prescribed safe limits. The system has been validated by using physiological data taken on human subjects over a wide range of ambient water temperatures. Corresponding enthalpy and electrical power measurements were used as the basis of a thermodynamic analysis. The DTPS maintained skin and body core temperatures within safe and functional ranges by providing up to about 200 W of heating in cold water and up to about 330 W of cooling in hot water. The corresponding electrical power consumption was up to about 300 W in cold water and up to about 1500 W in hot water. The results of a complete audit of the power use and heat transfer are presented along with the efficiency of the thermoelectric heating/cooling modules and the duty cycle of the system for a range of water immersion temperatures from 10°C to 39°C. The DTPS proved to be an effective and reliable apparatus for diver thermal protection in water temperatures from 10°C to 39°C, which covers most of the range of the earth’s waters. The data presented here can be used to modify the design of the DTPS to meet specific needs of the diving community.


Author(s):  
R. Friso ◽  
N. Casari ◽  
M. Pinelli ◽  
A. Suman ◽  
F. Montomoli

Abstract Gas turbines (GT) are often forced to operate in harsh environmental conditions. Therefore, the presence of particles in their flow-path is expected. With this regard, deposition is a problem that severely affects gas turbine operation. Components’ lifetime and performance can dramatically vary as a consequence of this phenomenon. Unfortunately, the operating conditions of the machine can vary in a wide range, and they cannot be treated as deterministic. Their stochastic variations greatly affect the forecasting of life and performance of the components. In this work, the main parameters considered affected by the uncertainty are the circumferential hot core location and the turbulence level at the inlet of the domain. A stochastic analysis is used to predict the degradation of a high-pressure-turbine (HPT) nozzle due to particulate ingestion. The GT’s component analyzed as a reference is the HPT nozzle of the Energy-Efficient Engine (E3). The uncertainty quantification technique used is the probabilistic collocation method (PCM). This work shows the impact of the operating conditions uncertainties on the performance and lifetime reduction due to deposition. Sobol indices are used to identify the most important parameter and its contribution to life. The present analysis enables to build confidence intervals on the deposit profile and on the residual creep-life of the vane.


Author(s):  
Weimar Mantilla ◽  
José García ◽  
Rafael Guédez ◽  
Alessandro Sorce

Abstract Under new scenarios with high shares of variable renewable electricity, combined cycle gas turbines (CCGT) are required to improve their flexibility, in terms of ramping capabilities and part-load efficiency, to help balance the power system. Simultaneously, liberalization of electricity markets and the complexity of its hourly price dynamics are affecting the CCGT profitability, leading the need for optimizing its operation. Among the different possibilities to enhance the power plant performance, an inlet air conditioning unit (ICU) offers the benefit of power augmentation and “minimum environmental load” (MEL) reduction by controlling the gas turbine inlet temperature using cold thermal energy storage and a heat pump. Consequently, an evaluation of a CCGT integrated with this inlet conditioning unit including a day-ahead optimized operation strategy was developed in this study. To establish the hourly dispatch of the power plant and the operation mode of the inlet conditioning unit to either cool down or heat up the gas turbine inlet air, a mixed-integer linear optimization (MILP) was formulated using MATLAB, aiming to maximize the operational profit of the plant within a 24-hours horizon. To assess the impact of the proposed unit operating under this dispatch strategy, historical data of electricity and natural gas prices, as well as meteorological data and CO2 emission allowances price, have been used to perform annual simulations of a reference power plant located in Turin, Italy. Furthermore, different equipment capacities and parameters have been investigated to identify trends of the power plant performance. Lastly, a sensitivity analysis on market conditions to test the control strategy response was also considered. Results indicate that the inlet conditioning unit, together with the dispatch optimization, increases the power plant’s operational profit by achieving a wider operational range, particularly important during peak and off-peak periods. For the specific case study, it is estimated that the net present value of the CCGT integrated with the ICU is 0.5% higher than the power plant without the unit. In terms of technical performance, results show that the unit reduces the minimum environmental load by approximately 1.34% and can increase the net power output by 0.17% annually.


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