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.

Development of an Air Cooled G Class Gas Turbine (the M501GAC)

2009 ◽  
Author(s):  
Toshishige Ai ◽  
Carlos Koeneke ◽  
Hisato Arimura ◽  
Yoshinori Hyakutake
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Inlet Temperature ◽  
Air Cooling ◽  
National Project ◽  
Commercial Operation ◽  
Steam Cooling ◽  
Verification Test ◽  
Verification Process ◽  
Verification Plan

Mitsubishi Heavy Industries (MHI) G series gas turbine is the industry pioneer in introducing steam cooling technology for gas turbines. The first M501G unit started commercial operation in 1997 and to date, with 62 G units sold, MHI G fleet is the largest steam cooled fleet in the market. The existing commercial fleet includes 35 commercial units with more than 734,000 accumulated actual operating hours, and over 9,400 starts. Upgraded versions have been introduced in the 60 and 50Hz markets (M501G1 and M701G2 respectively). On a different arena, MHI is engaged since 2004 in a Japanese National Project for the development of 1,700°C (3092°F) class gas turbine. Several enhanced technologies developed through this Japanese National Project, including lower thermal conductivity TBC, are being retrofitted to the existing F and G series gas turbines. Retrofitting some of these technologies to the existing M501G1 together with the application of an F class air cooled combustion system will result in an upgraded air-cooled G class engine with increased power output and enhanced efficiency, while maintaining the same 1500°C (2732°F) Turbine Inlet Temperature (TIT). By using an open air cooling scheme, this upgraded machine represents a better match for highly cyclic applications with G class efficiency, while the highly reliable and durable steam cooled counterpart is still offered for more base-loaded applications. After performing various R&D tests, the verification process of the air cooled 60 Hz G gas turbine has moved to component testing in the in-house verification engine. The final verification test prior to commercial operation is scheduled for 2009. This article describes the design features and verification plan of the upgraded M501G gas turbine.

Numerical Simulation on Gas Turbine Film Cooling of Curved Surface With Backward Injection

2012 ◽  
Author(s):  
Shashank Shetty ◽  
Xianchang Li ◽  
Ganesh Subbuswamy
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Strong Mixing ◽  
Inlet Temperature ◽  
Film Cooling Effectiveness ◽  
Aerodynamic Loss

Due to the unique role of gas turbine engines in power generation and aircraft propulsion, significant effort has been made to improve the gas turbine performance. As a result, the turbine inlet temperature is usually elevated to be higher than the metal melting point. Therefore, effective cooling of gas turbines is a critical task for engines’ efficiency as well as safety and lifetime. Film cooling has been used to cool the turbine blades for many years. The main issues related to film cooling are its poor coverage, aerodynamic loss, and increase of heat transfer coefficient due to strong mixing. To overcome these problems, film cooling with backward injection has been found to produce a more uniform cooling coverage under low pressure and temperature conditions and with simple cylindrical holes. Therefore, the focus of this paper is on the performance of film cooling with backward injection at gas turbine operating conditions. By applying numerical simulation, it is observed that along the centerline on both concave and convex surfaces, the film cooling effectiveness decreases with backward injection. However, cooling along the span is improved, resulting in more uniform cooling.

Gas Turbine Fouling: The Influence of Climate and Part-Load Operating Conditions

2019 ◽  
Author(s):  
Nicola Aldi ◽  
Nicola Casari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Alternative Fuels ◽  
Environmental Influence ◽  
Electrical Power ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Continuous Increase ◽  
Part Load

Abstract Energy and climate change policies associated with the continuous increase in natural gas costs pushed governments to invest in renewable energy and alternative fuels. In this perspective, the idea to convert gas turbines from natural gas to syngas from biomass gasification could be a suitable choice. Biogas is a valid alternative to natural gas because of its low costs, high availability and low environmental impact. Syngas is produced with the gasification of plant and animal wastes and then burnt in gas turbine combustor. Although synfuels are cleaned and filtered before entering the turbine combustor, impurities are not completely removed. Therefore, the high temperature reached in the turbine nozzle can lead to the deposition of contaminants onto internal surfaces. This phenomenon leads to the degradation of the hot parts of the gas turbine and consequently to the loss of performance. The amount of the deposited particles depends on mass flow rate, composition and ash content of the fuel and on turbine inlet temperature (TIT). Furthermore, compressor fouling plays a major role in the degradation of the gas turbine. In fact, particles that pass through the inlet filters, enter the compressor and could deposit on the airfoil. In this paper, the comparison between five (5) heavy-duty gas turbines is presented. The five machines cover an electrical power range from 1 MW to 10 MW. Every model has been simulated in six different climate zones and with four different synfuels. The combination of turbine fouling, compressor fouling, and environmental conditions is presented to show how these parameters can affect the performance and degradation of the machines. The results related to environmental influence are shown quantitatively, while those connected to turbine and compressor fouling are reported in a more qualitative manner. Particular attention is given also to part-load conditions. The power units are simulated in two different operating conditions: 100 % and 80 % of power rate. The influence of this variation on the intensity of fouling is also reported.

scholarly journals Implementation of Adaptive Neuro-fuzzy Model to Optimize Operational Process of Multiconfiguration Gas-Turbines

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Chao Deng ◽  
Ahmed N. Abdalla ◽  
Thamir K. Ibrahim ◽  
MingXin Jiang ◽  
Ahmed T. Al-Sammarraie ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Anfis Model ◽  
Neuro Fuzzy ◽  
Compressor Efficiency

In this article, the adaptive neuro-fuzzy inference system (ANFIS) and multiconfiguration gas-turbines are used to predict the optimal gas-turbine operating parameters. The principle formulations of gas-turbine configurations with various operating conditions are introduced in detail. The effects of different parameters have been analyzed to select the optimum gas-turbine configuration. The adopted ANFIS model has five inputs, namely, isentropic turbine efficiency (Teff), isentropic compressor efficiency (Ceff), ambient temperature (T1), pressure ratio (rp), and turbine inlet temperature (TIT), as well as three outputs, fuel consumption, power output, and thermal efficiency. Both actual reported information, from Baiji Gas-Turbines of Iraq, and simulated data were utilized with the ANFIS model. The results show that, at an isentropic compressor efficiency of 100% and turbine inlet temperature of 1900 K, the peak thermal efficiency amounts to 63% and 375 MW of power resulted, which was the peak value of the power output. Furthermore, at an isentropic compressor efficiency of 100% and a pressure ratio of 30, a peak specific fuel consumption amount of 0.033 kg/kWh was obtained. The predicted results reveal that the proposed model determines the operating conditions that strongly influence the performance of the gas-turbine. In addition, the predicted results of the simulated regenerative gas-turbine (RGT) and ANFIS model were satisfactory compared to that of the foregoing Baiji Gas-Turbines.

Operability Limits of Tubular Injectors With Vortex Generators for a Hydrogen-Fueled Recuperated 100 kW Class Gas Turbine

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Stefan Bauer ◽  
Balbina Hampel ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Bulk Flow ◽  
Vortex Generators ◽  
Inlet Temperature ◽  
Test Rig ◽  
Temperature Range ◽  
Wide Range

Abstract Vortex generators are known to be effective in augmenting the mixing of fuel jets with air. The configuration investigated in this study is a tubular air passage with fuel injection from one single orifice placed in the side wall. In the range of typical gas turbine combustor inlet temperatures, the performance vortex generator premixers (VGPs) have already been investigated for natural gas as well as for blends of natural gas and hydrogen. However, for highly reactive fuels, the application of VGPs in recuperated gas turbines is particularly challenging because the high combustor inlet temperature leads to potential risk with regard to premature self-ignition and flame flashback. As the current knowledge does not cover the temperature range far above the self-ignition temperature, an experimental investigation of the operational limits of VGPs is currently being conducted at the Thermodynamics Institute of the Technical University of Munich, Garching, Germany, which is particularly focused on reactive fuels and the thermodynamic conditions present in recuperated gas turbines with pressure ratios of 4–5. For the study presented in this paper, an atmospheric combustion VGP test rig has been designed, which facilitates investigations in a wide range of operating conditions in order to comply with the situation in recuperated microgas turbines (MGT), namely, global equivalence ratios between 0.2 and 0.7, air preheating temperatures between 288 K and 1100 K, and air bulk flow rates between 6 and 16 g/s. Both the entire mixing zone in the VGP and the primary combustion zone of the test rig are optically accessible. High-speed OH* chemiluminescence imaging is used for the detection of the flashback and blow-off limits of the investigated VGPs. Flashback and blow-off limits of hydrogen in a wide temperature range covering the autoignition regime are presented, addressing the influences of equivalence ratio, air preheating temperature, and momentum ratio between air and hydrogen on the operational limits in terms of bulk flow velocity. It is shown that flashback and blow-off limits are increasingly influenced by autoignition in the ultrahigh temperature regime.

Analysis of Integrated Cooling Systems for Gas Turbine Power Plants

2017 ◽  
Author(s):  
Waleed El-Damaty ◽  
Mohamed Gadalla
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Air Cooling ◽  
Turbine Inlet Temperature ◽  
Current Increase ◽  
Turbine Inlet ◽  
Compact Size

With the current increase in electricity consumption and energy demand, most of the research focus is shifted towards the means of increasing the power plants efficiency in order to produce more electricity by using as less fuel as possible. Gas turbine power plants specifically have been under the study in the recent years due to its feasibility, low capital cost, simple design, compact size and higher efficiency compared to steam turbine power plants. There are a lot of operating conditions that affect the performance of the gas turbine which includes the inlet air climatic conditions, mass flow rate and the turbine inlet temperature. Many improvements and enhancements became applicable through the advancement in the material and cooling technologies. Cooling techniques could be used to cool the inlet air entering the compressor by utilizing evaporative coolers and mechanical chillers, and to cool the turbine blades in order to avoid a decline in the life of turbine blades due to unwanted exposure to thermal stresses and oxidation. Internal convection cooling, film cooling and transpiration cooling are the three main techniques that can be used in the process of turbine blades cooling. The main objective of this proposal is to improve the durability and performance of gas turbine power plants by proposing the usage of integrated system of solid desiccant with Maisotsenko cooler in the turbine blade cooling and inlet air cooling processes. Four configurations were presented and the results were an increase in the efficiency of the gas turbine cycle for all the cases specially the two stage Maisotsenko desiccant cooling system where the efficiency increased from 33.33% to 34.17% as well as maintaining the turbine inlet temperature at a desired level of 1500°K.

Systems Level Performance Estimations for a Pulse Detonation Combustor Based Hybrid Engine

2008 ◽  
Author(s):  
Venkat E. Tangirala ◽  
Narendra D. Joshi
Keyword(s):  
Gas Turbine ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Entire Range ◽  
Operating Conditions ◽  
Simple Cycle ◽  
Inlet Temperature ◽  
Specific Work ◽  
Pulse Detonation

The Pulse Detonation Combustor (PDC) has recently evoked much interest as a pressure-gain combustor for use in gas turbines. A key application for a Pulse Detonation Engine (PDE) concept has been envisioned as a hybrid power generation engine, which would replace the combustor in a conventional gas turbine with a PDC. Estimations of performance parameters, namely, thermal efficiency (ηth) and specific work (Wnet) are reported for a PDC based hybrid engine for various configurations of the engine. The performance enhancing configurations of the PDC-based hybrid engine, considered in the present study, include simple cycle, intercooling, regeneration and reheat, similar to the configurations for a conventional gas turbine (GT) engine in the literature. The performance estimations for a conventional gas turbine engine and a PDC based hybrid engine are compared for the same operating conditions (such as inlet pressure, inlet temperature, compression ratio, overall equivalence ratio) and for various configurations. The thermal efficiency of an intercooled PDC hybrid engine with regeneration has the highest value for the entire range of turbine pressure ratios, from 1.2 to 40 (corresponding to a compression ratio range of 1 to 30). An intercooled PDC based hybrid engine with reheat produces the highest specific work (Wnet) when compared to all other configurations. Among simple-cycle /regeneration /reheat configurations of a PDC based hybrid engine, ητh for the intercooled PDC based hybrid engines has the highest estimated value (0.47) at a turbine pressure ratio of 30. The intercooled PDC based hybrid engine also produces the highest specific work (Wnet) when compared to simple-cycle/regeneration/reheat hybrid engine configurations over the entire range of turbine pressure ratios.

Performance of Integrated Combined and Cogeneration Cycles Using Latest Gas Turbines

2004 ◽  
Author(s):  
Sanjay ◽  
Onkar Singh ◽  
B. N. Prasad
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Utilization Efficiency ◽  
Inlet Temperature ◽  
Air Cooling ◽  
Specific Work ◽  
Fuel Utilization ◽  
Compressor Pressure Ratio ◽  
Cogeneration Cycle

The paper deals with the thermodynamic performance of combined and cogeneration cycles using the state of the art gas turbines. A configuration has been conceptualized using the latest gas turbine MS9001H that uses steam to cool the hot gas path components. In order to study the effect of cooling means, the same gas turbine is subjected to transpiration air cooling. Using the above mentioned conceptualized topping cycle, the bottoming cycle selected consists of a two-pressure reheat heat recovery steam generator (HRSG) with reheat having two options. First option is the integrated system (IS), which is a combined/cogeneration cycle, and the other is called the normal cogeneration cycle (NC). Both of these cycles are subjected to steam and transpiration air-cooling. The cycle performance is predicted based on parameteric study which has been carried out by modeling the various elements of cycle such as gas, compressor combustor, cooed gas turbine, HRSG steam turbine, condenser, etc. The performance is predicted for parameters such as fuel utilization efficiency (ηf), power-to-heat-ratio (PHR), coolant flow requirements, plant specific work, etc. as a function of independent parameters such as compressor pressure ratio (rpc) and turbine inlet temperature (TIT), etc. The results predicted will be helpful for designers to select the optimum compressor pressure ratio and TIT to achieve the target fuel utilization efficiency, and PHR at the target plant specific work.

A Novel Concept for Combined Heat and Cooling in Humid Gas Turbine Cycles

2007 ◽  
Author(s):  
Alessandro Corradetti ◽  
Umberto Desideri ◽  
Ashok D. Rao
Keyword(s):  
Water Vapor ◽  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Sensitivity Analyses ◽  
Inlet Temperature ◽  
Electrical Efficiency ◽  
Novel Concept ◽  
Net Power Output

Various gas turbine cycles are known where water is introduced as a liquid or as a vapor into the combustor of the gas turbine. Such cycles include the Humid Air Turbine (HAT) cycle, the Steam Injected (STIG) cycle, and the Regenerated Water Injected gas turbine cycle (RWI). The effect of water vapor is the increasing of net power output and the reduction of NOx formation within the combustor. However the net increase in power output is limited in commercial models of gas turbines, because a large addition of water vapor leads to the mismatch between the compressor and the turbine. In this paper a possible method to solve this problem is proposed: it is based on a novel concept for combining refrigeration and power production in humid gas turbine cycles. In the proposed system a fraction of the air at compressor discharge is extracted, cooled to nearly ambient temperature, dried and expanded in a turbine. At turbine outlet the air is at a very low temperature and can be used for providing refrigeration. A thermodynamic analysis has been carried out to investigate the performance of the system in HAT, STIG and RWI cycles for different operating conditions representing the state of art of commercial gas turbines. In particular the pressure ratio and the turbine inlet temperature have been respectively varied in the range 7–45 and 900–1500°C. Sensitivity analyses have been performed to assess how the amounts of extracted air and injected steam affect the net power output, the electrical efficiency and the cooling. The results show that cryogenic temperatures (lower than −100°C) for refrigeration can be achieved in combination with very high electrical efficiency (over 40%, typical of humid gas turbine cycles).

scholarly journals Carbon Monoxide Emissions From Gas Turbines as Influenced by Ambient Temperature and Turbine Load

1992 ◽  
Author(s):  
W. S. Y. Hung
Keyword(s):  
Carbon Monoxide ◽  
Ambient Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
The United States ◽  
Operating Conditions ◽  
Limiting Factor ◽  
Federal Republic Of Germany ◽  
Water Steam ◽  
Combustion Systems

The emissions of carbon monoxide (CO) from gas turbines are typically below 100 ppmvd @ 15% O2 at design full-load operating conditions. The use of water/steam to reduce NOx emissions from gas turbines results in an increase in CO emissions from gas turbines. This is particularly true when increased rates of water/steam injection are used to meet stringent NOx limits. Regulations limiting CO emissions from stationary gas turbines were first initiated in the late 1980’s by the Federal Republic of Germany and the state of New Jersey in the United States. Since these regulations are silent on ambient and load corrections, these CO limits could be the limiting factor in the current development of dry low NOx combustion systems by gas turbine manufacturers. In addition, since manufacturers are usually quite specific regarding the conditions for CO guarantees, a conflict for the gas turbine user, who is responsible for the permit application, is readily apparent. This paper attempts to characterize the CO emissions from gas turbines as a function of ambient temperature and turbine load. An ambient temperature correction equation for CO emissions, based on previous work, is presented. The intent is to provide more extensive information on CO emissions such that better defined CO limits can be adopted. Ultimately, this should help the combustion design engineers in developing improved dry low emissions combustion systems for the gas turbine industry.

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