Residual Reactivity of Burned Gases in the Early Expansion Process of Future Gas Turbines

1996 ◽  
Vol 118 (1) ◽  
pp. 54-60 ◽  
Author(s):  
B. Leide ◽  
P. Stouffs
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Extreme Case ◽  
Inlet Temperature ◽  
Environmental Aspects ◽  
Expansion Process ◽  
Future Design ◽  
Expansion Path ◽  
Temperature And Pressure

The present study investigates the chemical evolution of the burned gases in a first-stage nozzle operated under high inlet temperature and pressure conditions as they are foreseen for next-generation high-efficiency gas turbine machinery. Coupled aerothermochemical simulations are performed up to the extreme case of stoichiometric combustion without ulterior dilution. The intent is to provide an estimation of possible consequences arising from the residual reactivity of gases downstream from the combustor. These consequences might affect the future design of the expansion path in order to render nonstationary chemistry compatible with aerodynamics, energetics, and environmental aspects.

Three Spool High Efficiency Small Scale Gas Turbine Concept

2017 ◽  
Author(s):  
Matti Malkamäki ◽  
Ahti Jaatinen-Värri ◽  
Antti Uusitalo ◽  
Aki Grönman ◽  
Juha Honkatukia ◽  
...  
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Small Scale ◽  
Inlet Temperature ◽  
Substantial Impact ◽  
Electrical Efficiency ◽  
Partial Load ◽  
Reciprocating Engines

Decentralized electricity and heat production is a rising trend in small-scale industry. There is a tendency towards more distributed power generation. The decentralized power generation is also pushed forward by the policymakers. Reciprocating engines and gas turbines have an essential role in the global decentralized energy markets and improvements in their electrical efficiency have a substantial impact from the environmental and economic viewpoints. This paper introduces an intercooled and recuperated three stage, three-shaft gas turbine concept in 850 kW electric output range. The gas turbine is optimized for a realistic combination of the turbomachinery efficiencies, the turbine inlet temperature, the compressor specific speeds, the recuperation rate and the pressure ratio. The new gas turbine design is a natural development of the earlier two-spool gas turbine construction and it competes with the efficiencies achieved both with similar size reciprocating engines and large industrial gas turbines used in heat and power generation all over the world and manufactured in large production series. This paper presents a small-scale gas turbine process, which has a simulated electrical efficiency of 48% as well as thermal efficiency of 51% and can compete with reciprocating engines in terms of electrical efficiency at nominal and partial load conditions.

scholarly journals 100s and 1000s Mw Open and Semi-Closed Cycle Gas Turbines for Base and Peak Operation

1974 ◽  
Author(s):  
V. V. Uvarov ◽  
V. S. Beknev ◽  
E. A. Manushin
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Simple Cycle ◽  
Inlet Temperature ◽  
Closed Cycle ◽  
Turbine Inlet Temperature ◽  
Unit Capacity ◽  
Temperature And Pressure ◽  
Different Levels

There are two different approaches to develop the gas turbines for power. One can get some megawatts by simple cycle or by more complex cycle units. Both units require very different levels of turbine inlet temperature and pressure ratio for the same unit capacity. Both approaches are discussed. These two approaches lead to different size and efficiencies of gas turbine units for power. Some features of the designing problems of such units are discussed.

Flameholding Tendencies of Natural Gas and Hydrogen Flames at Gas Turbine Premixer Conditions

2014 ◽  
Author(s):  
Elliot Sullivan-Lewis ◽  
Vincent McDonell
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
High Reliability ◽  
Elevated Pressure ◽  
Inlet Temperature ◽  
Increased Risk ◽  
Wide Range ◽  
Lean Premixed

Ground based gas turbines are responsible for generating a significant amount of electric power as well as providing mechanical power for a variety of applications. This is due to their high efficiency, high power density, high reliability, and ability to operate on a wide range of fuels. Due to increasingly stringent air quality requirements, stationary power gas turbines have moved to lean-premixed operation. Lean-premixed operation maintains low combustion temperatures for a given turbine inlet temperature, resulting in low NOx emissions while minimizing emissions of CO and hydrocarbons. In addition, to increase overall cycle efficiency, engines are being operated at higher pressure ratios and/or higher combustor inlet temperatures. Increasing combustor inlet temperatures and pressures in combination with lean-premixed operation leads to increased reactivity of the fuel/air mixture, leading to increased risk of potentially damaging flashback. Curtailing flashback on engines operated on hydrocarbon fuels requires care in design of the premixer. Curtailing flashback becomes more challenging when fuels with reactive components such as hydrogen are considered. Such fuels are gaining interest because they can be generated from both conventional and renewable sources and can be blended with natural gas as a means for storage of renewably generated hydrogen. The two main approaches for coping with flashback are either to design a combustor that is resistant to flashback, or to design one that will not anchor a flame if a flashback occurs. An experiment was constructed to determine the flameholding tendencies of various fuels on typical features found in premixer passage ways (spokes, steps, etc.) at conditions representative of a gas turbine premixer passage way. In the present work tests were conducted for natural gas and hydrogen between 3 and 9 atm, between 530 K and 650K, and free stream velocities from 40 to 100 m/s. Features considered in the present study include a spoke in the center of the channel and a step at the wall. The results are used in conjunction with existing blowoff correlations to evaluate flameholding propensity of these physical features over the range of conditions studied. The results illustrate that correlations that collapse data obtained at atmospheric pressure do not capture trends observed for spoke and wall step features at elevated pressure conditions. Also, a notable fuel compositional effect is observed.

The Energy Exchanger, a New Concept for High-Efficiency Gas Turbine Cycles

1967 ◽  
Vol 89 (2) ◽  
pp. 217-227 ◽  
Author(s):  
R. C. Weatherston ◽  
A. Hertzberg
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Energy Exchange ◽  
High Efficiency ◽  
Inlet Temperature ◽  
Viscous Effects ◽  
Isentropic Compression ◽  
Combustion Gas ◽  
Power Cycles ◽  
Compression Waves

A method of circumventing the turbine inlet temperature limitation of present-day gas turbines is presented. This method is based on a direct fluid-to-fluid energy exchanger whereby the available energy of expansion of the hot combustion gas in a gas turbine cycle is transferred directly to a colder gas. The aerodynamic wave processes in several possible modes of operation are examined to determine the inherent limitations in efficiency of direct fluid-to-fluid energy exchange processes. In particular, it is demonstrated that, by using a system of isentropic compression waves to avoid shock losses and by carefully choosing the molecular weights of the fluids utilized in the energy exchanger, perfect energy exchange is possible in principle. When allowances are made for losses due to mixing, leakage, and viscous effects, an energy exchanger utilizing heated combustion air at 3240 deg F to drive steam at 1500 deg F with a potential energy exchange efficiency of 85 percent is feasible. Applications of the air-steam energy exchanger operating in gas turbine cycles utilizing a conservative choice of component efficiencies indicate that thermal efficiencies of gas turbine power cycles of 50–60 percent may be possible.

scholarly journals Development of a High Pressure Ratio Centrifugal Compressor for 300kW-Class Ceramic Gas Turbine

1997 ◽  
Author(s):  
T. Sakai ◽  
Y. Tohbe ◽  
T. Fujii ◽  
T. Tatsumi
Keyword(s):  
Research And Development ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Flow Distribution ◽  
Leading Edge ◽  
Inlet Temperature ◽  
Angle Distribution ◽  
Gas Generator

Research and development of ceramic gas turbines (CGT), which is promoted by the Japanese Ministry of International Trade and Industry (MITI), was started in 1988. The target of the CGT project is development of a 300kW-class ceramic gas turbine with a 42 % thermal efficiency and a turbine inlet temperature (TIT) of 1350°C. Two types of CGT engines are developed in this project. One of the CGT engines, which is called CGT302, is a recuperated two-shaft gas turbine with a compressor, a gas-generator turbine, and a power turbine for cogeneration. In this paper, we describe the research and development of a compressor for the CGT302. Specification of this compressor is 0.89 kg/sec air flow rate and 8:1 pressure ratio. The intermediary target efficiency is 78% and the final target efficiency is 82%, which is the highest level in email centrifugal compressors like this one. We measured impeller inlet and exit flow distribution using three-hole yaw probes which were traversed from the shroud to the hub. Based on the measurement of the impeller exit flow, diffusers with a leading edge angle distribution adjusted to the inflow angle were designed and manufactured. Using this diffuser, we were able to attain a high efficiency (8:1 pressure ratio and 78% adiabatic efficiency).

scholarly journals Advantages of Air Conditioning and Supercharging an LM6000 Gas Turbine Inlet

1994 ◽  
Author(s):  
Donald A. Kolp ◽  
Harold A. Guidotti ◽  
William M. Flye
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Performance Enhancement ◽  
Heat Rate ◽  
Inlet Temperature ◽  
Factors Affecting ◽  
Subsequent Performance ◽  
Turbine Inlet ◽  
New Generation

Of all the external factors affecting a gas turbine, inlet pressure and temperature have the greatest impact on performance. The effect of inlet temperature variations is especially pronounced in the new generation of high-efficiency gas turbines typified by the 40 MW GE LM6000. A reduction of 50 F (28 C) in inlet temperature can result in a 30% increase in power and a 4.5% improvement in heat rate. An elevation increase to 5000 feet (1524 meters) above sea level decreases turbine output 17%; conversely supercharging can increase output more than 20%. This paper addresses various means of heating, cooling and supercharging LM6000 inlet air. An economic model is developed and sample cases are cited to illustrate the optimization of gas turbine inlet systems, taking into account site conditions, incremental equipment cost and subsequent performance enhancement.

Advantages of Air Conditioning and Supercharging an LM6000 Gas Turbine Inlet

1995 ◽  
Vol 117 (3) ◽  
pp. 513-527 ◽  
Author(s):  
D. A. Kolp ◽  
W. M. Flye ◽  
H. A. Guidotti
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Performance Enhancement ◽  
Heat Rate ◽  
Inlet Temperature ◽  
Factors Affecting ◽  
Subsequent Performance ◽  
Turbine Inlet ◽  
Percent Improvement

Of all the external factors affecting a gas turbine, inlet pressure and temperature have the greatest impact on performance. The effect of inlet temperature variations is especially pronounced in the new generation of high-efficiency gas turbines typified by the 40 MW GE LM6000. A reduction of 50°F (28°C) in inlet temperature can result in a 30 percent increase in power and a 4.5 percent improvement in heat rate. An elevation increase to 5000 ft (1524 m) above sea level decreases turbine output 17 percent; conversely supercharging can increase output more than 20 percent. This paper addresses various means of heating, cooling and supercharging LM6000 inlet air. An economic model is developed and sample cases are cited to illustrate the optimization of gas turbine inlet systems, taking into account site conditions, incremental equipment cost and subsequent performance enhancement.

On Thermodynamics of Gas-Turbine Cycles: Part 2—A Model for Expansion in Cooled Turbines

1986 ◽  
Vol 108 (1) ◽  
pp. 151-159 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Approximate Model ◽  
Operating Conditions ◽  
Limiting Factor ◽  
Inlet Temperature ◽  
Air Cooling ◽  
Closed Form Solutions ◽  
Key Factor ◽  
Expansion Path

While raising turbine inlet temperature improves the efficiency of the gas-turbine cycle, the increasing turbine-cooling losses become a limiting factor. Detailed prediction of those losses is a complex process, thought to be possible only for specific designs and operating conditions. A general, albeit approximate, model is presented to quantify those cooling losses for different types of cooling technologies. It is based upon representing the turbine as an expansion path with continuous, rather than discrete, work extraction. This enables closed-form solutions to be found for the states along the expansion path as well as turbine work output. The formulation shows the key factor in determining the cooling losses is the parameter scaling the ratio of heat to work fluxes loading the machine surfaces. Solutions are given for three cases: internal air-cooling, transpiration air cooling, and internal liquid cooling. The first and second cases represent lower and upper bounds respectively for the performance of film-cooled machines. Irreversibilities arising from flow-path friction, heat transfer, cooling air throttling, and mixing of coolant and mainstream are quantified and compared. Sample calculations for the performance of open and combined cycles with cooled turbines are presented. The dependence and sensitivity of the results to the various loss mechanisms and assumptions is shown. Results in this paper pertain to Brayton-cycle gas turbines with the three types of cooling mentioned. Reheat gas turbines are more sensitive to cooling losses due to the larger number of high-temperature stages. Those are considered in Part 3.

Upgrading the Undergraduate Gas Turbine Lab

2014 ◽  
Author(s):  
Zachary Lee ◽  
Shane Lowe ◽  
Bret P. Van Poppel ◽  
Michael J. Benson ◽  
Aaron St. Leger
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Gas Turbines ◽  
Air Flow ◽  
Combustion Process ◽  
The United States ◽  
Virtual Laboratory ◽  
Inlet Temperature ◽  
Physical Laboratory ◽  
Temperature And Pressure

A study of gas turbine engines is an important component of an integrated thermodynamics and fluid mechanics two-course sequence at the United States Military Academy (USMA). Owing to the ubiquity of gas turbines in military use, graduating cadets will encounter a variety of these engines throughout their military careers. Especially for this unique population, it is important for engineering students to be familiar with the operation and applications of gas turbines. Experimental analysis of a functional auxiliary power unit (APU) from an Army utility helicopter has been a key component of this block of instruction for several decades. As with all laboratory equipment, the APU has experienced intermittent maintenance issues, which occasionally render it unusable for the gas turbine laboratory in the course. Because of this, a very basic virtual laboratory was implemented which integrated video of the physical laboratory with key parameters and behind-the-screen data collection for use in engine analysis. A revitalized version of both the physical and virtual gas turbine laboratory experiences offered in the thermal-fluids course will include substantial improvements over the existing setup. The physical laboratory, which is centered on a refurbished APU from a medium-sized commercial aircraft, will continue to incorporate measurements of temperature and pressure throughout the combustion process, as well as fuel flow rate. In an improvement over the original laboratory setup, an orifice plate will be used to measure the flow rate of bleed air exiting the turbine, which had not previously been open during engine testing. Additionally, the air flow through the anti-surge valve was not metered in the original version of the physical laboratory. However, the anti-surge air flow can account for nearly 25% of the total air flow, and performance calculations in the physical laboratory will now account for this loss. The turbine output shaft will run a water-brake dynamometer. All instrumentation will be converted to digital signals and projected on a large screen outside the test area through a LabVIEW front panel. The virtual laboratory will include the same metering options as the operational APU. In addition, the virtual laboratory will include the option to alter engine operating parameters, such as inlet temperature and pressure or exhaust temperatures, and students may conduct broad parameter sweeps across ranges of possible inputs or desired outputs. These improvements will enable students to gain a deeper understanding of gas turbine operation and capabilities in practical applications. The improved laboratory will be implemented in Spring, 2014.

Gas Turbine Fouling: A Comparison Among 100 Heavy-Duty Frames

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Nicola Aldi ◽  
Nicola Casari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Efficiency ◽  
Particle Deposition ◽  
High Efficiency ◽  
Inlet Temperature ◽  
Low Grade ◽  
Outlet Temperature ◽  
Heavy Duty

Over recent decades, the variability and high costs of the traditional gas turbine fuels (e.g., natural gas) have pushed operators to consider low-grade fuels for running heavy-duty frames. Synfuels, obtained from coal, petroleum, or biomass gasification, could represent valid alternatives in this sense. Although these alternatives match the reduction of costs and, in the case of biomass sources, would potentially provide a CO2 emission benefit (reduction of the CO2 capture and sequestration costs), these low-grade fuels have a higher content of contaminants. Synfuels are filtered before the combustor stage, but the contaminants are not removed completely. This fact leads to a considerable amount of deposition on the nozzle vanes due to the high temperature value. In addition to this, the continuous demand for increasing gas turbine efficiency determines a higher combustor outlet temperature. Current advanced gas turbine engines operate at a turbine inlet temperature (TIT) of (1400–1500) °C, which is high enough to melt a high proportion of the contaminants introduced by low-grade fuels. Particle deposition can increase surface roughness, modify the airfoil shape, and clog the coolant passages. At the same time, land-based power units experience compressor fouling, due to the air contaminants able to pass through the filtration barriers. Hot sections and compressor fouling work together to determine performance degradation. This paper proposes an analysis of the contaminant deposition on hot gas turbine sections based on machine nameplate data. Hot section and compressor fouling are estimated using a fouling susceptibility criterion. The combination of gas turbine net power, efficiency, and TIT with different types of synfuel contaminants highlights how each gas turbine is subjected to particle deposition. The simulation of particle deposition on 100 gas turbines ranging from 1.2 MW to 420 MW was conducted following the fouling susceptibility criterion. Using a simplified particle deposition calculation based on TIT and contaminant viscosity estimation, the analysis shows how the correlation between type of contaminant and gas turbine performance plays a key role. The results allow the choice of the best heavy-duty frame as a function of the fuel. Low-efficiency frames (characterized by lower values of TIT) show the best compromise in order to reduce the effects of particle deposition in the presence of high-temperature melting contaminants. A high-efficiency frame is suitable when the contaminants are characterized by a low-melting point thanks to their lower fuel consumption.

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