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1
Aguilar, Ricardo Jose. "Ultra-low power microbridge gas sensor." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43723.
Full textAbstract:
A miniature, ultra-low power, sensitive, microbridge gas sensor has been developed.The heat loss from the bridge is a function of the thermal conductivity of thegas ambient. Miniature thermal conductivity sensors have been developed for gaschromatography systems [1] and microhotplates have been built with MEMS technologywhich operates within the mW range of power [2]. In this work a lower power microbridgewas built which allowed for the amplification of the effect of gas thermalconductivity on heat loss from the heated microbridge due to the increase inthe surface-to-volume ratio of the sensing element. For the bridge fabrication,CMOS compatible technology, nanolithography, and polysilicon surfacemicromachining were employed. Eight microbridges were fabricated on each die,of varying lengths and widths, and with a thickness of 1 μm.
A voltagewas applied to the sensor and the resistance was calculated based upon thecurrent flow. The response has been tested with air, carbon dioxide, helium,and nitrogen. The resistance and temperature change for carbon dioxide was thegreatest, while the corresponding change for helium was the least. Thus the selectivity of the sensor todifferent gases was shown, as well as the robustness of the sensor. Another aspect of the sensor is that it hasvery low power consumption. The measuredpower consumption at 4 Volts is that of 11.5 mJ for Nitrogen, and 16.1 mJ forHelium.
Thesensor responds to ambient gas very rapidly. The time constant not only showsthe fast response of the sensor, but it also allows for more accuratedetection, given that each different gas produces a different correspondingtime constant from the sensor. The sensor is able to detect differentconcentrations of the same gas as well. Fromthe slopes that were calculated, the resistance change at 5 Volts operation wasfound to be 2.05mΩ/ppm, 1.14 mΩ/ppm at 4.5 Volts, and 0.7 mΩ/ppm at 4 Volts. Thehigher voltages yielded higher resistance changes for all of the gases thatwere tested.
Theversatility of the microbridge has been studied as well. Experiments were donein order to research the ability of a deposited film on the microbridge, inthis case tin oxide, to act as a sensing element for specific gases. In thissetup, the microbridge no longer is the sensing element, but instead acts as aheating element, whose sole purpose is to keep a constant temperature at whichit can then activate the SnO film, making it able to sense methane.
In conclusion,the microbridge was designed, fabricated, and tested for use as an electrothermalgas sensor. The sensor responds to ambient gas very rapidly with differentlevels of resistance change for different gases, purely due to the differencein thermal conductivity of each of the gases. Not only does it have a fastresponse, but it also operates at low power levels. Further research has beendone in the microbridge's ability to act as a heating element, in which the useof a SnO film as the sensing element, activated by the microbridge, was studied.
REFERENCES:
1. D. Cruz,J.P. Chang, S.K. Showalter, F. Gelbard, R.P. Manginell, M.G. Blain," Microfabricated thermal conductivity detector for themicro-ChemLabTM," Sensors andActuators B, Vol. 121 pp. 414-422, (2007).
2. A. G. Shirke, R. E. Cavicchi, S. Semancik, R. H. Jackson, B.G. Frederick, M. C. Wheeler. "Femtomolar isothermal desorption usingmicrohotplate sensors," J Vac Sci TechnolA, Vol. 25, pp. 514-526 (2007).
2
Bartlett, Michael. "Developing Humidified Gas Turbine Cycles." Doctoral thesis, KTH, Chemical Engineering and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3437.
Full textAbstract:
As a result of their unique heat recovery properties,Humidified Gas Turbine (HGT) cycles have the potential todeliver resource-effective energy to society. The EvaporativeGas Turbine (EvGT) Consortium in Sweden has been studying thesetypes of cycles for nearly a decade, but now stands at acrossroads, with commercial demonstration remaining. Thisthesis binds together several key elements for the developmentof humidified gas turbines: water recovery and air and waterquality in the cycle, cycle selection for near-term, mid-sizedpower generation, and identifying a feasible niche market fordemonstration and market penetration. Moreover, possiblesocio-technical hinders for humidified gas turbine developmentare examined.
Through modelling saltcontaminant flows in the cycle andverifying the results in the pilot plant, it was found thathumidification tower operation need not endanger the hot gaspath. Moreover, sufficient condensate can be condensed to meetfeed water demands. Air filters were found to be essential tolower the base level of contaminant in the cycle. This protectsboth the air and water stream components. By capturing airparticles of a similar size to the air filters, the humidifieractually lowers air stream salt levels. Measures to minimisedroplet entrainment were successful (50 mg droplets/kg air) andmodels predict a 1% blow down from the water circuit issufficient. The condensate is very clean, with less than 1 mg/lalkali salts and easily deionised.
Based on a core engine parameter analysis for three HGTcycle configurations and a subsequent economic study, asteam-cooled steam injected cycle complemented with part-flowhumidification is recommended for the mid-size power market.This cycle was found to be particularly efficient at highpressures and turbine inlet temperatures, conditions eased bysteam cooling and even intercooling. The recommended HGT cyclegives specific investment costs 30- 35% lower than the combinedcycles and cost of electricity levels were 10-18% lower.Full-flow intercooled EvGT cycles give high performances, butseem to be penalised by the recuperator costs, while stillbeing cheaper than the CC. District heating is suggested as asuitable niche market to commercially demonstrate the HGTcycle. Here, the advantages of HGT are especially pronounceddue their very high total efficiencies. Feasibility prices forelectricity were up to 35% lower than competing combinedcycles. HGT cycles were also found to effectively include wasteheat sources.
Keywords:gas turbines, evaporative gas turbines,humidification, power generation, combined heat and powergeneration.
3
Chen, Shang-Liang. "The effects of gas composition and rippled power on laser gas cutting." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333679.
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4
Armillei, Claudio. "Modellazione di sistemi energetici Power to Gas." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13360/.
Full textAbstract:
Questo lavoro prevede la costruzione di un modello Matlab Simulink dell'elettrolizzatore a membrana polimerica e del metanatore Sabatier, che tiene in considerazione tutti i parametri di funzionamento come temperatura, pressione, tipologia di catalizzatore e dimensioni delle celle permettendo la simulazione del processo in regime dinamico o stazionario. Il modello dell'elettrolizzatore è stato validato per elettrolizzatori AEM (membrana scambio anionico) attraverso prove sperimentali presso l'impianto Fenice dell'ENEA.
E' stata poi analizzata l'integrazione dei sistemi PtG al fotovoltaico di diversa potenza di picco, per valutarne la compatibilità. Si è visto che connettendo un elettrolizzatore AEM e PEM di 5.5 kW con FV di diversa potenza di picco (5 kW,7kW e 10 kW) si riesce ad accumulare nel migliore dei casi il 43 % dell'energia prodotta da fotovoltaico sotto forma di idrogeno. Se si procede a metanazione questo valore scende al 33 %. Tuttavia gli impianti lavorano ad efficienza quasi massima (58% per AEM e 65% per il PEM) anche ad un regime intermittente.
In seguito è stata condotta un'analisi economica di come i sistemi PtG sono influenzati dal PUN (Prezzo Unico Nazionale) dell'energia elettrica. Si è visto di come sia molto conveniente utilizzare il PtG per produzione di idrogeno per applicazioni tecniche, con tempi di ritorno dell'investimento di pochi anni.
Infine si è analizzata la convenienza economica di impianti FV che non godono più degli incentivi di Conto Energia di rivendere energia elettrica alla rete al prezzo del PUN o alimentare PtG. Ipotizzando tre prezzi di vendita per idrogeno come prodotto per applicazioni e come combustibile e metano, si è visto che nel primo caso è molto più conveniente produrre gas, mentre negli altri due casi i flussi di cassa sono equivalenti. L'immissione dell'idrogeno nella rete gas esistente permetterebbe l'accumulo di energia e studi dimostrano che non comporti rischi aggiuntivi, dimostrandone la compatibilità.
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Tagner, Nikita, and Arian Abedin. "Thermodynamic model for power generating gas turbines." Thesis, KTH, Energiteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170917.
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Gasturbiner används i en mängd olika sammanhang, från kraftgenerering till flygplansmotorer. Prestandan hos gasturbiner beror på omgivningstillstånd såsom temperatur och tryck. Gasturbintillverkare förser ofta vissa parametrar, exempelvis uteffekt och massflöde i avgaserna vid väldefinierade standard tillstånd, ofta refererade till som ISO-tillstånd. På grund av det tidigare beskrivna beroendet är det nödvändigt för köpare att kunna förutspå prestandan vid platsen där gasturbinen ska användas. I denna studie har en termodynamisk modell för kraftgenerande gasturbiner konstruerats. Modellen förutspår uteffekten vid full belastning för varierande omgivningstemperatur och omgivningstryck. Den konstruerade modellen har jämförts med prestandadata från Siemens egna modeller, vid varieande temperatur. Prestandadata för varierande tryck kunde inte erhållas. Den konstruerade modellen är konsekvent med Siemens modeller inom vissa temperaturintervall vars längd beror på den utvärderade gasturbinens storlek. För mindre gasturbiner är temperaturintervallet för vilken den konstruerade modellen är konsekvent längre än för större gasturbiner.Gas turbines are used for a variety of purposes ranging from power generation to aircraft engines. Their performance is dependent on ambient conditions such as temperature and pressure. Gas turbine manufacturers often provide certain parameters like power output and exhaust mass flow at well-defined standard conditions, usually referred to as ISO-conditions. Due to the aforementioned dependency, it is necessary for buyers to be able to predict gas turbine performance at their chosen site of operation. In this study, a thermodynamic model for power generating gas turbines has been constructed. It predicts the power output at full load for varying ambient temperature and pressure. The constructed model has been compared with performance data taken from Siemens own models for varying temperatures. No performance data for varying pressures could be obtained. The constructed model is consistent with the Siemens models within certain temperature intervals, which differ depending on the size of the gas turbine. For smaller gas turbines, the interval where the constructed model is consistent is greater than for larger gas turbines.
6
Leung, Tommy (Tommy Chun Ting). "Coupled natural gas and electric power systems." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98547.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Engineering Systems Division, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 235-240).
Scarce pipeline capacity in regions that rely on natural gas technologies for electricity generation has created volatile prices and reliability concerns. Gas-fired generation firms uniquely operate as large consumers in the gas market and large producers in the electricity market. To explore the effects of this coupling, this dissertation investigates decisions for firms that own gas-fired power plants by proposing a mixed-integer linear programming model that explicitly represents multi-year pipeline capacity commit- ments and service agreements, annual forward capacity offers, annual maintenance schedules, and daily fuel purchases and electricity generation. This dissertation's primary contributions consist of a detailed representation of a gas-fired power-plant owner's planning problem; a hierarchical application of a state-based dimensionality reduction technique to solve the hourly unit commitment problem over different tem- poral scales; a technique to evaluate a firm's forward capacity market offer, including a probabilistic approach to evaluate the risk of forced outages; a case study of New England's gas-electricity system; and an exploration of the applicability of forward capacity markets to reliability problems for other basic goods.
by Tommy Leung.
Ph. D.
7
Zavadil, Jan. "Sezónní akumulace využívající technologii power-to-gas." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417449.
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The diploma thesis is focusing on the seasonal energy storage in synthetic fuels and the Power to Gas system (P2G). The P2G enables the conversion of electrical energy in times of electricity surplus, for example by using the surplus from renewable energy sources to produce synthetic gas, particulary hydrogen and synthetic methane. The main focus is on the technical and economic assessment of P2G of the Gazela natural gas pipeline. Furthermore, it identifies the limits of production, transportation, and storage capacities of these synthetic gases. The technical analysis assumes the injection of hydrogen of a certain molar concentration, according to the four proposed scenarios, into the natural gas transmission system in the Gazela pipeline. The results have showen that an increase in the molar fraction of hydrogen in natural gas will cause problems in gas transport and will lead to an increase in the pressure losses, an increase in flow rate, and a decrease in the storage capacity of the pipeline. The economic analysis examines the use of P2G technology in Czech conditions. It demonstrates the amount of production costs for the production of 1 MWh of synthetic gas depending on the electricity price and the operating time of the production facility. The sensitivity analysis has shown that neither hydrogen nor synthetic methane is competitive next to cheap natural gas unless measures like an increased price of emission allowances or a carbon tax are taken.
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Ojha, Abhi. "Coupled Natural Gas and Electric Power Systems." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78666.
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Decreasing gas prices and the pressing need for fast-responding electric power generators are currently transforming natural gas networks. The intermittent operation of gas-fired plants to balance wind generation introduces spatiotemporal fluctuations of increasing gas demand. At the heart of modeling, monitoring, and control of gas networks is a set of nonlinear equations relating nodal gas injections and pressures to flows over pipelines. Given gas demands at all points of the network, the gas flow task aims at finding the rest of the physical quantities. For a tree network, the problem enjoys a closed-form solution; yet solving the equations for practical meshed networks is non-trivial. This problem is posed here as a feasibility problem involving quadratic equalities and inequalities, and is further relaxed to a convex semidefinite program (SDP) minimization. Drawing parallels to the power flow problem, the relaxation is shown to be exact if the cost function is judiciously designed using a representative set of network states. Numerical tests on a Belgian gas network corroborate the superiority of the novel method in recovering the actual gas network state over a Newton-Raphson solver. This thesis also considers the coupled infrastructures of natural gas and electric power systems. The gas and electric networks are coupled through gas-fired generators, which serve as shoulder and peaking plants for the electric power system. The optimal dispatch of coupled natural gas and electric power systems is posed as a relaxed convex minimization problem, which is solved using the feasible point pursuit (FPP) algorithm. For a decentralized solution, the alternating direction method of multipliers (ADMM) is used in collaboration with the FPP. Numerical experiments conducted on a Belgian gas network connected to the IEEE 14 bus benchmark system corroborate significant enhancements on computational efficiency compared with the centralized FPP-based approach.Master of Science
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Al-Hamdan, Qusai Zuhair Mohammed. "Design criteria and performance of gas turbines in a combined power and power (CPP) plant for electrical power generation." Thesis, University of Hertfordshire, 2002. http://hdl.handle.net/2299/14041.
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The simple gas turbine engine Operates on the basic Joule-Brayton cycle and it is notorious for its poor thermal efficiency. Several modifications have been made to the simple cycle in order to increase its thermal efficiency but, within the thermal and mechanical stress constrains, the efficiency still ranges between 28 and 35%. However, higher values of energy utilisation efficiency have been claimed in recent years by using low grade heat from the engine exhaust either for district heating or for raising low pressure steam for chemical processes. Both applications are not very attractive in hot countries. The concept of using the low grade thermal energy from the gas turbine exhaust to raise steam in order to drive a steam turbine and generate additional electricity, i. e. the combined power and power or CPP plant would be more attractive in hot countries than the CHP plant. It was hypothesized that the operational parameters, hence the performance of the CPP plant, would depend on the allowable gas turbine entry temperature. Hence, the exhaust gas temperature could not be decided arbitrarily. This thesis deals with the performance of the gas turbine engine operating as a part of the combined power and power plant. In a CPP plant, the gas turbine does not only produce power but also the thermal energy that is required to operate the steam turbine plant at achievable thermal efficiency. The combined gas turbine-steam turbine cycles are thermodynamically analysed. A parametric study for different configurations of the combined gas-steam cycles has been carried out to show the influence of the main parameters on the CPP cycle performance. The parametric study was carried out using realistic values in view of the known constraints and taking into account any feasible future developments. The results of the parametric study show that the maximum CPP cycle efficiency would be at a point for which the gas turbine cycle would have neither its maximum efficiency nor its maximum specific work output. It has been shown that supplementary heating or gas turbine reheating would decrease the CPP cycle efficiency; hence, it could only be justified at low gas turbine inlet temperatures. Also it has been shown that although gas turbine intercooling would enhance the performance of the gas turbine cycle, it would have only a slight effect on the CPP cycle performance. A graphical method for studying operational compatibility, i.e. matching, between gas turbine components has been developed for a steady state or equilibrium operation. The author would like to submit that the graphical method offers a novel and easy to understand approach to the complex problem of component matching. It has been shown that matching conditions between the compressor and the turbine could be satisfied by superimposing the turbine performance characteristics on the compressor performance characteristics providing the axes of both were normalised. This technique can serve as a valuable tool to determine the operating range and the engine running line. Furthermore, it would decide whether the gas turbine engine was operating in a region of adequate compressor and turbine efficiencies. A computer program capable of simulating the steady state off-design conditions of the gas turbine engine as part of the CPP plant has been developed. The program was written in Visual Basic. Also, another program was developed to simulate the steady state off-design operation of the steam turbine power plant. A combination of both programs was used to simulate the combined power plant. Finally, it could be claimed that the computer simulation of the CPP plant makes significant contribution to the design of thermal power plants as it would help in investigating the effects of the performance characteristics of the components on the performance of complete engines at the design and off-design conditions. This investigation of the CPP plant performance can be carried out at the design and engineering stages and thus help to reduce the cost of manufacturing and testing the expensive prototype engines.
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Papadopoulos, Tilemachos. "Gas turbine cycles for intermediate load power generation." Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/10718.
Full textAbstract:
The
objective of this thesis is to determine if an advanced gas turbine cycle exists,
which can
compete with the simple and the combined cycles in the intermediate load
electricity generation market; defined as the market with annual utilisation between
3,000 to 6,000 operating hours.
Several
thermodynamic cycles in the 100MW and 200MW power output range are
investigated and compared to base reference simple and combined cycles that have
been defined
by a survey of existing models in the market.
For the
investigation of these cycles, gt-ETA (gas turbine - Economic and Technical
Analysis) has been developed; a software for the design and off-design
thermodynamic performance and the economic evaluation of gas turbine cycles.
A new method is
proposed for calculating the total capital investment of a advanced
cycle engine project. This is based on deriving empirical relations linking the
purchased equipment cost to power output and thermal efficiency, based on published
data for
simple cycle engines. Standardised values are used for the specific costs of
different
performance improvement' packages.
A
optimisation process is developed for the determination of the optimum split
between the
capital investment of a baseline' simple cycle engine and a 'performance
improvement package.
For accurate
performance calculations a cooling air model has been created based on
either the direct definition of
cooling air amounts or the required hot gas path
component metal temperatures. The model is able to select the optimum cooling
configuration considering the temperature and pressure of mixing streams.
The advanced
cycles are competitive against base reference cycles only in the power
range of l00MW. From the configurations considered, the recuperated cycle with
spray intercooling seems to be the most promising option with a wide range of
competitiveness at both design and off-design operating conditions and along the
sensitivity range of changing fuel prices.
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Bashadi, Sarah (Sarah Omer). "Using auxiliary gas power for CCS energy needs in retrofitted coal power plants." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59667.
Full textAbstract:
Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 93-96).
Post-combustion capture retrofits are expected to a near-term option for mitigating CO 2 emissions from existing coal-fired power plants. Much of the literature proposes using power from the existing coal plant and thermal integration of its supercritical steam cycle with the stripper reboiler to supply the energy needed for solvent regeneration and CO2 compression. This study finds that using an auxiliary natural gas turbine plant to meet the energetic demands of carbon capture and compression may make retrofits more attractive compared to using thermal integration in some circumstances. Natural gas auxiliary plants increase the power output of the base plant and reduce technological risk associated with CCS, but require favorable natural gas prices and regional electricity demand for excess electricity to make using an auxiliary plant more desirable. Three different auxiliary plant technologies were compared to integration for 90% capture from an existing, 500 MW supercritical coal plant. CO2 capture and compression is simulated using Aspen Plus and a monoethylamine (MEA) absorption process. Thermoflow software is used to simulate three gas plant technologies. The three technologies assessed are the gas turbine (GT) with heat recovery steam generator (HRSG), gas turbine with HRSG and back pressure steam turbine, and natural gas boiler with back pressure steam turbine. The capital cost of the MEA unit is estimated using the Aspen Icarus Process Evaluator, and the capital cost of the external GT plants are estimated using the Thermoflow Plant Engineering and Cost Estimator. The gas turbine options are found to lead to electricity costs similar to integration, but their performance is highly sensitive to the price of natural gas and the economic impact of integration. Using a GT with a HRSG only has a lower capital cost but generates less excess electricity than the GT with HRSG and back pressure steam turbine. In order to generate enough steam for the reboiler, a significant amount of excess power was produced using both gas turbine configurations. This excess power could be attractive for coal plants located in regions with increasing electricity demand. An alternate capture plant scenario where a greater demand for power exists relative to steam is also considered. The economics of using auxiliary plant power improve slightly under this alternate energy profile scenario, but the most important factors affecting desirability of the auxiliary plant retrofit remain the cost of natural gas, the full cost of integration, and the potential for sale of excess electricity.
by Sarah Bashadi.
S.M.in Technology and Policy
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Bloemhof, Barbara Lynn Mestelman Stuart. "Market power and the sale of Ontario residential natural gas: An institutional analysis and a laboratory experiment." *McMaster only, 2004.
Find full text
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Uvwie, Patrick Awaciere. "Nigeria's gas flaring reduction : economic viability of power generation using flared gas / P.A. Uvwie." Thesis, North-West University, 2008. http://hdl.handle.net/10394/3697.
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Austrem, Inger. "The exergy efficiency of hydrogen-fired gas power plants." Thesis, Norwegian University of Science and Technology, Industrial Ecology Programme, 2003. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1427.
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The work includes an exergy analysis of the steam reforming process for conversion of natural gas to hydrogen rich gas for use in hydrogen-fired gas power plant. Based on the analysis two sustainability indicators were calculated, the exergetic efficiency and the renewability fraction. The same analysis has been performed for a system using auto thermal reformer (Zvolinschi, Kjelstrup, Bolland and van der Kooi 2002) instead of steam reformer, and the results were compared in order to find the better system of the two based on the indicators. The system using an auto thermal reformer had the best exergetic efficiency, and the renewability fraction was 0 for both systems. One should be aware of insecurities in the results, mainly related to assumptions and limitations with respect to the simulation process.
The two indicators were proposed by Zvolinschi et. al, as a contribution to the introduction of exergy analysis as a tool for industrial ecology. It was concluded that this will be a useful contribution, especially when using system boundaries that include the closure of material cycles. Then one can also calculate the third indicator proposed by Zvolinschi et al., namely the environmental efficiency.
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Hayko, Robert Kory. "Systems approach to natural gas analysis for power generation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ30858.pdf.
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Yakah, Noah. "Heat Exchanger Design for Solar Gas-Turbine Power Plant." Thesis, KTH, Energiteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107277.
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The aim of this project is to select appropriate heat exchangers out of available gas-gas heat exchangers for used in a proposed power plant. The heat exchangers are to be used in the power plant for the purposes of waste heat recovery, recuperation and intercooling.In selecting an optimum heat exchanger for use, the PCHE was identified as the best candidate for waste heat recovery and recuperation. In order to ascertain the viability of this assertion the PCHE was designed and a 1D modeling performed in MATLAB using the conditions that the heat exchanger for waste heat recovery would be subjected to. The choice of using the conditions that the waste recovery heat exchanger would be subjected to was due to the fact that, it is the heat exchanger that would be subjected to much harsh conditions (thus higher temperatures of up to 650 ºC). The PFHE was also designed and similarly a 1D modeling performed in MATLAB. The decision to consider the design of the PFHE was to offer a platform to compare and contrast the performance of the PCHE in order to have a strong basis for deciding on whether to stick to the choice for the PCHE or otherwise.The results obtained from the 1D modeling of the design of the heat exchangers indicates that the PCHE performed better with regards to pressure drops across the heat exchangers (with values of 1.17 and 2.47 % for the cold and hot sides respectively), compactness (with a value of 1300 m2/m3 for the PCHE compared to the 855 m2/m3 recorded from the PFHE), however the PFHE recorded higher heat transfer coefficients, and a subsequent higher overall transfer coefficient.Results obtained from the simulation of the 3D model buttress the decision to employ the PCHE as heat exchangers to be used for waste heat recovery and recuperation as a wise one, with an effectiveness of 0.94 as against the design value of 0.90, and with pressure drops as desired of the optimum heat exchanger.
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Tsoutsanis, Elias. "Performance adaptation of gas turbines for power generation applications." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5614.
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One of the greatest challenges that the world is facing is that of providing everyone access to safe and clean energy supplies. Since the liberalization of the electricity market in the UK during the 1990s many combined cycle gas turbine (CCGT) power plants have been developed as these plants are more energy efficient and friendlier to the environment. The core component in a combined cycle plant is the gas turbine. In this project the MEA’s Pulrose Power Station CCGT plant is under investigation. This plant cronsists of two aeroderivative LM2500+ gas turbines of General Electric for producing a total of 84MW power in a combined cycle configuration. Cont/d.
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Spelling, James. "Hybrid Solar Gas-Turbine Power Plants : A Thermoeconomic Analysis." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121315.
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The provision of a sustainable energy supply is one of the most importantissues facing humanity at the current time, and solar thermal power hasestablished itself as one of the more viable sources of renewable energy. Thedispatchable nature of this technology makes it ideally suited to forming thebackbone of a future low-carbon electricity system.However, the cost of electricity from contemporary solar thermal power plantsremains high, despite several decades of development, and a step-change intechnology is needed to drive down costs. Solar gas-turbine power plants are apromising new alternative, allowing increased conversion efficiencies and asignificant reduction in water consumption. Hybrid operation is a furtherattractive feature of solar gas-turbine technology, facilitating control andensuring the power plant is available to meet demand whenever it occurs.Construction of the first generation of commercial hybrid solar gas-turbinepower plants is complicated by the lack of an established, standardised, powerplant configuration, which presents the designer with a large number ofchoices. To assist decision making, thermoeconomic studies have beenperformed on a variety of different power plant configurations, includingsimple- and combined-cycles as well as the addition of thermal energy storage.Multi-objective optimisation has been used to identify Pareto-optimal designsand highlight trade-offs between costs and emissions.Analysis of the simple-cycle hybrid solar gas-turbines revealed that, whileelectricity costs were kept low, the achievable reduction in carbon dioxideemissions is relatively small. Furthermore, an inherent trade-off between thedesign of high efficiency and high solar share hybrid power plants wasidentified. Even with the use of new optimised designs, the degree of solarintegration into the gas-turbine did not exceed 63% on an annual basis.In order to overcome the limitations of the simple-cycle power plants, twoimprovements were suggested: the integration of thermal energy storage, andthe use of combined-cycle configurations. Thermal energy storage allowed thedegree of solar operation to be extended, significantly decreasing carbondioxide emissions, and the addition of a bottoming-cycle reduced the electricitycosts. A combination of these two improvements provided the bestperformance, allowing a reduction in carbon dioxide emissions of up to 34%and a reduction in electricity costs of up to 22% compared to a combination ofconventional power generation technologies.Hållbar energiförsörjning är för närvarande en av de viktigaste frågorna förmänskligheten. Koncentrerad solenergi är nu etablerad som en tillförlitlig källaav förnybar energi. Den reglerbara karaktären hos tekniken gör den specielltintressant för uppbyggnaden av ett framtida koldioxidsnålt elsystem.Kostnaden för elektricitet från nuvarande termiska solkraftverk är hög trottsflera decennier av utveckling. Ett genombrått på tekniknivå krävs för att drivaned kostnaderna. Sol-gasturbiner är ett av de mest lovande alternativen, somger en ökad verkningsgrad samtidigt som vattenkonsumtionen reducerasdrastiskt. Sol-gasturbintekniken gör det möjligt att blandköra solenergi ochandra bränslen för att möta efterfrågan vid alla tidpunkter, en attraktiv aspekt iförhållande till alternativa lösningar.Uppbyggnaden av första generationens kommersiella hybrida solgasturbinkraftverkförsvåras dock av bristen på etablerade och standardiseradekraftverkskonfigurationer. Dessa ger planeraren ett stort antal valmöjlighetersom underlag för beslutsfattande. Termoekonomiska studier har genomförtsför ett flertal olika kraftverkskonfigurationer, däribland kraftverk med enkelcykel, kombikraftverk samt möjligheten att utnyttja termisk energilagring.Pareto-optimala konfigurationer har identifierats med hjälp av multiobjektsoptimeringför att belysa balansen mellan kostnader och utsläpp.Analysen av det enkla hybrida sol-gasturbinkraftverket visade attelektricitetskostnaden hållits på en låg nivå, men att den möjliga minskningen avkoldioxidutsläpp är relativt liten. Dessutom identifierades en inre balans mellanatt bibehålla en hög verkningsgrad hos konfigurationen och en hög andelsolenergi i produktionen. Andelen av solenergi i gasturbinen överskred aldrig63% på årlig bas, även med optimerade kraftverkskonfigurationer.Två förbättringar föreslås för att övervinna begränsningarna hos kraftverk medenkel cykel: integration av termisk energilagring samt nyttjande avkombikraftverkskonfigurationer. Termisk energilagring tillåter en ökad andelsolenergi i driften och reducerar koldioxidutsläppen drastiskt, medan denytterligare cykeln hos kombikraftverket reducerar elektricitetskostnaden.Kombinationen av dessa förbättringar ger den bästa prestandan, med enreduktion av koldioxidutsläppen på upp till 34% och reducerade elektricitetskostnaderpå upp till 22% i jämförelse med andra kombinationer avkonventionella kraftverkskonfigurationer.
QC 20130503
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AVELLAR, VINICIUS PIMENTA DE. "TRANSIENT MODELLING OF INDUSTRIAL GAS TURBINE FOR POWER GENERATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16332@1.
Full textAbstract:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROAs turbinas a gás são equipamentos de vital importância para o setor industrial, fornecendo trabalho e calor para diversos setores, do transporte aos sistemas de cogeração. A crescente necessidade de geração de energia elétrica confiável tem incentivado o projeto de turbinas a gás industriais, inclusive no Brasil, que operam com vários combustíveis como o diesel, gás natural, álcool e de combustíveis de baixo poder calorífico. Para melhor monitorar e controlar estes motores, uma análise completa da previsão de funcionamento em regime transitório é necessária. Durante o regime transitório das turbinas a gás industriais (heavy-duty), o sistema de controle deve manter os limites de certos parâmetros, tais como a temperatura na entrada da turbina e a velocidade de rotação do eixo, no seu valor nominal. Além disso, o tempo de resposta necessário para o sistema de controle atuar deve ser o mais breve possível para garantir uma operação de qualidade, segura e confiável. A temperatura de entrada da turbina, que é um parâmetro muito importante no desempenho de uma turbina a gás, é limitada pela resistência mecânica do material das pás da turbina. A velocidade de rotação do eixo deve permanecer constante, devido à ligação ao sistema elétrico, que não pode suportar altas flutuações de freqüência. Este trabalho tem como motivação o incremento da capacidade de simulação de um modelo computacional existente, incorporando, para este fim, rotinas de sistemas de controle. Como resultado, o novo modelo é capaz de simular qualquer condição de funcionamento de turbinas a gás industriais, em regime permanente e transitório controlado. Os resultados obtidos pelo programa computacional se mostraram fiéis ao comportamento real da máquina. Além disso, mostraram a flexibilidade do modelo ao lidar com diferentes condições de operação.Um programa computacional capaz de simular o desempenho transitório controlado de turbinas a gás é de extrema relevância para o desenvolvimento de softwares que auxiliam os operadores destes equipamentos. Dentre estes, estão os sistemas de monitoramento e diagnóstico dos equipamentos em questão.
Gas turbine engines are a vital part of today’s industry, providing both work and heat for several industry sectors, from transportation to cogeneration systems. The growing need for reliable electricity has encouraged the design of stationary gas turbines, including in Brazil, which operates on multiple fuels such as diesel, natural gas and low calorific fuels. To better monitor and control these engines, a complete analysis for prediction of transient operation is required. During transient operation of heavy duty gas turbines, the control system must keep the limits of certain parameters, such as turbine inlet temperature (TIT) and the rotational shaft speed within their design range. Moreover, the time required for the control system to react should be as short as possible to guarantee a safe and reliable operation. The turbine inlet temperature, which is a very important parameter in the performance of a gas turbine, is limited by the turbine blades material mechanical resistance. Furthermore, the rotational speed should remain constant due to the electric grid connection, which cannot withstand high frequency fluctuations. This work is motivated by the need to increase the ability of a computer model to simulate the performance of industrial gas turbines, incorporating, for this purpose, control system routines. As a result, the new model will be able to simulate any operating condition of industrial gas turbines, in both steady state and transient. The results obtained by the computer program proved to be faithful to the actual behavior of the engine. Furthermore, they showed the flexibility of the model to deal with different operating conditions. A computer program capable of simulating the transient performance of gas turbines is very important for the development softwares to help operators of such equipment. In addition, it could be used in on-line intelligent diagnostic program.
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Norring, Robert. "Optimum utilization of fission power with gas core reactors." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004060.
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Hosseini, Seyed. "State estimation of integrated power and gas distribution networks." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/109819/.
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Future energy networks are likely to be highly integrated with several energy conversion utilities operating between them, which make the control and management of the whole system more complicated. Therefore, analysis of operation and management of the whole system needs to be performed in an integrated approach. In order to perform an effective control and management of the whole system, an accurate and reliable estimation of the state parameters and the energy flows within the integrated network is essential. In this research simulation and state estimation of integrated power and gas distribution networks with decentralised injection and generation in both networks was investigated. For this purpose, state estimation of individual networks was first reviewed. Afterwards, state estimation of integrated power and gas distribution networks was studied. Firstly, an algorithm was developed for state estimation of power distribution networks, which was validated through a case study power distribution network. Afterwards, an algorithm for placement of additional measurements within power distribution networks for improvement of state estimation results was developed. The performance of the algorithm showed satisfactory results for placement of a given number of additional individual measurements and a given number of additional measurement units. Secondly, an algorithm was developed for simulation of operation of gas distribution networks with decentralised injection, which was validated with the results of the commercial software Synergi Gas. Then, an algorithm was developed for the WLS state estimation of gas distribution networks with decentralised injection, which was validated on a case study gas distribution network. Afterwards, an algorithm was developed for placement of additional measurements within gas distribution networks with decentralised injection for improvement of estimation of the gas mixtures within the network, which showed satisfactory results on a case study gas distribution network. Finally, an algorithm was developed for performing state estimation of power and gas distribution networks with decentralised injection and generation in both networks, which was validated on a case study power and gas distribution network. Afterwards, impact of deployment of smart meters on improvement of estimation of the state parameters of the other coupled network was investigated. It was observed that information from one of the energy networks has no significant impact on improvement of state estimation results of the other coupled network.
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PALMIERI, ALESSANDRO. "Gas Turbine Power Generators, Innovative Sliding Mode Load Controller." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1049110.
Full textAbstract:
This thesis deals with the design of an innovative load controller for heavy-duty gas turbine power generators and with its practical implementation on real industrial power plants. A robust controller based on the Sliding Mode control technique is designed, in order to improve the performance of the gas turbine system with respect to the traditional Proportional-Integral-Derivative based regulation currently employed. As a matter of fact, such regulation encounters many difficulties when the system operates in off-design conditions, which is the most frequent situation, leading to a deterioration of the gas turbine performance. This work is developed in collaboration with Ansaldo Energia S.p.A., which is one of the most important heavy-duty gas turbines manufacturing company in the world. The interaction with the industrial partner represents one of the key points of this thesis since the proposed controller could be implemented on real industrial microprocessors and it was possible to validate its performance in a Real Time Simulation environment in the Ansaldo Energia R&D laboratories. The controller validation, performed in a Hardware-In-the-Loop set-up, showed highly satisfactory results and important improvements in comparison with the traditional regulation of the GT power generator.
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Dalili, Farnosh. "Humidification in Evaporative Power Cycles." Doctoral thesis, KTH, Chemical Engineering and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3469.
Full textAbstract:
Evaporative gas turbine cycles (EvGT) show an exceptionalexhaust heat recovery potential, which makes them a strongcompetitor to other advanced gas turbine cycles, especiallyfrom small to intermediate sizes. Evaporative gas turbines aredistinguished by humidifying the working fluid beforecombustion at temperatures below the boiling point of water;and the heat required for evaporation of water is partly takenout of the exhaust gas. Thus, humidification is a key operationin these cycles. This thesis investigates, both theoreticallyand experimentally, two alternative approaches tohumidification: the packed-bed humidification tower and thetubular humidifier. Both these equipments involvecountercurrent contact between water and the working fluid.Humidifier design criteria are developed and criticalparameters such as flooding, wetting rate and entrainment arediscussed. The experimental parts were carried out on thepacked-bed tower in the EvGT pilot plant, and on a tubularhumidifier test rig especially erected for this purpose. Thetheoretical models were confirmed by the experiments.
The height of a transfer unit, necessary for designingpacked beds, was calculated for the packing employed in theEvGT pilot plant. It was found that the data provided by themanufacturer may be used with minor corrections.
The tubular test rig operated satisfactorily delivering hothumid air. The theoretical models coincided well with theexperimental results, verifying the design criteria developedhere. The heat transfer calculations indicated that mostresistance to heat transfer is on the exhaust gas side. Thus, asurface extended tube (Sunrod) was used in the test rig. Itcould be concluded that the tubular humidifier is a strongalternative to the packed-bedtower, especially in smallhigh-pressure gas turbines.
Furthermore, the importance of the non-ideality of theair-water vapor mixture in modeling evaporative cycles wasfirst highlighted in this work. Through applying realthermodynamic properties of air-water vapor mixtures in cyclecalculations, it was found that the compressed air contains ahigher amount of moisture than indicated by the ideal gasmixture model. This affects the design of the heat recoverysystem and cannot be neglected.
Key words:evaporative gas turbine, indirect-fired gasturbine, humidification, packed bed, tubular humidifier,evaporator, saturator.
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Tao, Fengfeng. "Advanced High-Frequency Electronic Ballasting Techniques for Gas Discharge Lamps." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/25978.
Full textAbstract:
Small size, light weight, high efficacy, longer lifetime and controllable output are the main advantages of high-frequency electronic ballasts for gas discharge lamps. However, power line quality and electromagnetic interference (EMI) issues arise when a simple peak rectifying circuit is used. To suppress harmonic currents and improve power factor, input-current-shaping (ICS) or power-factor-correction (PFC) techniques are necessary.
This dissertation addresses advanced high-frequency electronic ballasting techniques by using a single-stage PFC approach. The proposed techniques include single-stage boost-derived PFC electronic ballasts with voltage-divider-rectifier front ends, single-stage PFC electronic ballasts with wide range dimming controls, single-stage charge-pump PFC electronic ballasts with lamp voltage feedback, and self-oscillating single-stage PFC electronic ballasts.
Single-stage boost-derived PFC electronic ballasts with voltage-divider-rectifier front ends are developed to solve the problem imposed by the high boost conversion ratio required by commonly used boost-derived PFC electronic ballast. Two circuit implementations are proposed, analyzed and verified by experimental results.
Due to the interaction between the PFC stage and the inverter stage, extremely high bus-voltage stress may exist during dimming operation. To reduce the bus voltage and achieve a wide-range dimming control, a novel PFC electronic ballast with asymmetrical duty-ratio control is proposed. Experimental results show that wide stable dimming operation is achieved with constant switching frequency.
Charge-pump (CP) PFC techniques utilize a high-frequency current source (CS) or voltage source (VS) or both to charge and discharge the so-called charge-pump capacitor in order to achieve PFC. The bulky DCM boost inductor is eliminated so that this family of PFC circuits has the potential for low cost and small size. A family of CPPFC electronic ballasts is investigated. A novel VSCS-CPPFC electronic ballast with lamp-voltage feedback is proposed to reduce the bus-voltage stress. This family of CPPFC electronic ballasts are implemented and evaluated, and verified by experimental results.
To further reduce the cost and size, a self-oscillating technique is applied to the CPPFC electronic ballast. Novel winding voltage modulation and current injection concepts are proposed to modulate the switching frequency. Experimental results show that the self-oscillating CS-CPPFC electronic ballast with current injection offers a more cost-effective solution for non-dimming electronic ballast applications.Ph. D.
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Markovic, Dejan. "Induced currents in gas pipelines due to nearby power lines." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060807.155002/index.html.
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Karlsson, Linnéa. "Kombinera vindkraftsproduktion med vätgastillverkning : En studie om lönsamheten i processen Power to Gas to Power." Thesis, Mittuniversitetet, Avdelningen för ekoteknik och hållbart byggande, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-41962.
Full textAbstract:
Det måste hela tiden finnas en balans mellan produktion och konsumtion i ett elkraftsystem. Om balansen inte upprätthålls kan hela systemet kollapsa och det skulle påverka allt som drivs av elektricitet. Vindkraften har ökat kraftigt i Sverige och förväntas fortsatt öka allt mer. Vindkraft är väderberoendeproduktion vilket gör att det inte går att planera den exakta produktionsmängden. Det kan medföra problem till elkraftsystemet och balansen blir svår att upprätthålla. Vindkraften producerar inte alltid el när efterfrågan finns. Det skapas då ett behov av energilagring för att möta efterfrågan på el. Energilagring i form av vätgas har sina fördelar i att vätgasen har ett högt energiinnehåll och går att lagra under en lång tid. Syftet med arbetet är att undersöka potentialen för Mullbergs vindkraftpark att kombinera vindkraftsproduktion med vätgastillverkning ur ett lönsamhetsperspektiv. Ett verktyg i Excel gjordes för att beräkna elproduktionskostnaderna för vindkraftparken, vätgasproduktionskostnaderna för elektrolysörerna och elproduktionskostnaderna för vätgasturbinen. Resultatet visade att en stor del av elproduktionen från Mullbergs vindkraftpark inte är lönsam, att elpriserna är lägre än elproduktionskostnaden. Vätgasproduktion med elektrolysörerna visade sig vara lönsam då kostnaden för att producera ett kilo vätgas blev lägre än referensvärdet hämtat från Vätgas Sverige. Slutsatsens som kunde dras är att vätgasturbiner inte bör användas för att producera elektricitet av vätgas då elproduktionskostnaderna blir för höga för att matcha elpriserna.There must always be a balance between production and consumption in an electric power system. If the balance is not maintained, the entire system could collapse and it would affect everything that is powered by electricity. Wind power has increased sharply in Sweden and is expected to continue to increase. Wind power is weather dependent production, which means that it is not possible to plan the exact production volume. This can cause problems with the electric power system and the balance becomes difficult to maintain. Wind power does not always produce electricity when demand exists. This creates a need for energy storage to meet the demand for electricity. Energy storage in the form of hydrogen has its advantages in that the hydrogen gas has a high energy content and can be stored for a long time. The purpose of this work is to investigate the potential for Mullberg's wind power farm to combine wind power generation with hydrogen production from a profitability perspective. A tool in Excel was made to calculate the electricity generation costs for the wind power farm, the hydrogen production costs for the electrolysers and the electricity generation costs for the hydrogen turbine. The result showed that a large part of the electricity generated from Mullberg's wind farm is not profitable, that electricity prices are lower than the electricity production cost. Hydrogen production with the electrolysers proved to be profitable as the cost of producing one kilo of hydrogen gas was lower than the reference value obtained from Vätgas Sverige. The conclusion that could be drawn is that hydrogen gas turbines should not be used to produce electricity from hydrogen as electricity generation costs become too high to match the electricity price.
2020-05-06
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Boltyanskiy, Boris. "Operation of the heat and power complex Alatyr to power Russian oil and gas facilities." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264245.
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B. Boltyansky Operation of the heat and power complex Alatyr to power Russian oil and gas facilities, Master's Dissertation, 2017 - 102 pages, 26 tables, 30 figures Supervisor Prof. V. G. Kucherov, Doctor of Sciences, Department of Energy Technology. The work includes the following. A calculation of the main thermodynamic cycle of the heat and power complex Alatyr heat and power complex. A consideration of various schemes of using the Rankine organic cycle WERE integrated in the Alatyr heat and power complex with the aim of increasing energy efficiency. Conclusions about the feasibility of using the heat and power complex Alatyr. Conclusions about the feasibility of integration of the organic Rankine cycle. Economic comparison of the heat and power complex Alatyr with similar facilities on the distributed power generation market. Economic analysis of the comparison of energy blocks of HPC Alatyr with similar designs from other countries.B. Boltyansky Drift av värme- och kraftkomplexet Alatyr till makten Ryska olje- och gasanläggningar, Masters uppläggning, 2017 - 102 sidor, 26 tabeller, 30 figurer Handledare Prof. VG Kucherov, doktorsexamen, kandidatexamen för teknisk vetenskap, institutionen för termodynamik och termisk motorer. Arbetet innehåller följande. En beräkning av värmekraftkomplexets värmeoch kraftkomplex Alatyrs värmekomplex. En övervägning av olika system för användning av Rankine organiska cykeln var integrerad i Alatyr värme- och kraftkomplexet i syfte att öka energieffektiviteten. Slutsatser om möjligheten att använda värme- och kraftkomplexet Alatyr. Slutsatser om möjligheten att integrera den organiska Rankine-cykeln. Ekonomisk jämförelse av värme- och kraftkomplexet Alatyr med liknande anläggningar på den distribuerade kraftproduktionsmarknaden. Ekonomisk analys av jämförelsen av energiblock av HPC Alatyr med liknande konstruktioner från andra länder.
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Herraiz, Palomino Laura. "Selective exhaust gas recirculation in combined cycle gas turbine power plants with post-combustion carbon capture." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/23460.
Full textAbstract:
Selective Exhaust Gas Recirculation (S-EGR) consists of selectively transferring CO2 from the exhaust gas stream of a gas-fired power plant into the air stream entering the gas turbine compressor. Unlike in “non-selective” Exhaust Gas Recirculation (EGR) technology, recirculation of, principally, nitrogen does not occur, and the gas turbine still operates with a large excess of air. Two configurations are proposed: one with the CO2 transfer system operating in parallel to the post-combustion carbon capture (PCC) unit; the other with the CO2 transfer system operating downstream of, and in series to, the PCC unit. S-EGR allows for higher CO2 concentrations in the flue gas of approximately 13-14 vol%, compared to 6.6 vol% with EGR at 35% recirculation ratio. The oxygen levels in the combustor are approximately 19 vol%, well above the minimum limit of 16 vol% with 35% EGR reported in literature. At these operating conditions, process model simulations show that the current class of gas turbine engines can operate without a significant deviation in the compressor and the turbine performance from the design conditions. Compressor inlet temperature and CO2 concentration in the working fluid are critical parameters in the assessment of the effect on the gas turbine net power output and efficiency. A higher turbine exhaust temperature allows the generation of additional steam which results in a marginal increase in the combined cycle net power output of 5% and 2% in the investigated configurations with S-EGR in parallel and S-EGR in series, respectively. With aqueous monoethanolamine scrubbing technology, S-EGR leads to operation and cost benefits. S-EGR in parallel operating at 70% recirculation, 97% selective CO2 transfer efficiency and 96% PCC efficiency results in a reduction of 46% in packing volume and 5% in specific reboiler duty, compared to air-based combustion CCGT with PCC, and of 10% in packing volume and 2% in specific reboiler duty, compared to 35% EGR. S-EGR in series operating at 95% selective CO2 transfer efficiency and 32% PCC efficiency results in a reduction of 64% in packing volume and 7% in specific reboiler duty, compared to air-based, and of 40% in packing volume and 4% in specific reboiler duty, compared to 35% EGR. An analysis of key performance indicators for selective CO2 transfer proposes physical adsorption in rotary wheel systems as an alternative to selective CO2 membrane systems. A conceptual design assessment with two commercially available adsorbent materials, activated carbon and Zeolite X13, shows that it is possible to regenerate the adsorbent with air at near ambient temperature and pressure. Yet, a significant step change in adsorbent materials is necessary to design rotary adsorption systems with dimensions comparable to the largest rotary gas/gas heat exchanger used in coal-fired power plants, i.e. approximately 24 m diameter and 2 m height. An optimisation study provides guidelines on the equilibrium parameters for the development of materials. Finally, a technical feasibility study of configuration options with rotary gas/gas heat exchangers shows that cooling water demand around the post-combustion CO2 capture system can be drastically reduced using dry cooling systems where gas/gas heat exchangers use ambient air as the cooling fluid. Hybrid cooling configurations reduce cooling and process water demand in the direct contact cooler of a wet cooling system by 67% and 35% respectively, and dry cooling configurations eliminate the use of process and cooling water and achieve adequate gas temperature entering the absorber.
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Qureshi, Suhail Aftab. "Calculation of fast transients in gas insulated substations." Thesis, University of Manchester, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363514.
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Sullivan, Dustin L. Kovaleski Scott D. "Laser target triggering of gas switches." Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/5670.
Full textAbstract:
The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 5, 2009). Thesis advisor: Dr. Scott Kovaleski. Includes bibliographical references.
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Lietz, Franziska [Verfasser]. "Rechtlicher Rahmen für die Power-to-Gas-Stromspeicherung / Franziska Lietz." Baden-Baden : Nomos Verlagsgesellschaft mbH & Co. KG, 2017. http://d-nb.info/1160322422/34.
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Gillie, Mary. "Operation and regulation of a 'virtual wind/gas' power plant." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405322.
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Basurto, M. T. "Study of fuel cell and gas turbine hybrid power systems." Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/10514.
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Environmental awareness and the interest in distributed generation caused by
electricity market de-regulation are factors that promote research on renewable energies.
Fuel cells transform the chemical energy stored in fuel into electricity by
means of electrochemical reactions. Among the different fuel cell types, high temperature
fuel cells (HTFCS) have many advantages: high efficiency, low emissions,
fuel flexibility, modularity and high quality waste heat. The main disadvantage is their
high cost - however, this will be reduced when HTFCS are commercialised.
The
synergy between HTFCS and gas turbines (GTS) makes HTPC/GTS very
efficient
power systems for the generation of electricity, from kilowatts to just a few
megawatts.
The
present work focuses on HTFC/GT power systems, analysing their
performance, studying some particular applications, and making an economic
assessment. The final objective of this Thesis is to define a procedure to assist in the
preliminary design of HTFC/GT systems.
The authors main contribution is the definition of the Green-Cell Code
capable of simulating HTFC/GT systems, the study of their interest for several
applications, and the generation of a decision-making method for the preliminary design
of HTFC/GT
systems.
The
design and off-design simulation of HTFC/GT cycles have been carried
out with the integration of a code developed by the author to simulate HTFC
performance, and a commercial code to simulate GT performance. This work is even
more valuable
given the lack of commercial tools to analyse the system.
All of the technical and economic work is collected in a set of charts that
assist the
procedure of HTFC/GT cycle selection.
These charts show that HTFC/GT systems currently achieve thermal
efficiencies of about 60%, and will be capable of achieving up to 73% in the future.
This is of great interest for power generation applications. The use of a recuperate is
required to optimise the performance of the gas turbine and the fuel cell; it is also
interesting to use it to generate the maximum amount of power from the HTFC, in order
to reduce emissions and increase overall efficiency. Results show that Pressurised
MCFC/GT
Cycles achieve better performance and economic results that Atmospheric
MCFC/GT
Cycles. For Pressurised MCFC/GT Cycles, the optimum stack operating
pressure is between 5 and 10 bars. The installation of a combustor in Pressurised
MCFC/GT
cycles leads to higher specific power, higher unit costs of electricity, higher
CHP
efficiency, and lower thermal efficiency.
The use of HTFC/GT
cycles to generate heat and power must be seen as a
way to improve HTFC/GT efficiency by using the waste heat of exhaust gases, rather
than as an
optimum application.
Results also show that SOFC/GT systems achieve slightly higher results than
MCFC/GT
systems. Thus, the choice between MCFCs and SOFCs will be based on
durability and cost issues rather than on performance issues.
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Bellgren, Sofia, and Isabel Sondén. "Coupling of Nuclear Power Generation with Greenhouse Gas Capture Technology." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297557.
Full textAbstract:
In order to stop the escalating global warming, humankind rapidly needs to develop and implement technology to lower the level of carbon dioxide in the atmosphere. Today there are methods to capture CO2 directly from the atmosphere (DAC); the problem lies in how to power them in a fossil-free and cost-attractive way. This report will focus on the application of thermal waste energy from nuclear power for DAC. To enable the coupling of the power plant to the DAC, the thermal waste energy i. e. low-pressure steam from the plant's thermal cycle, has to be brought to a higher temperature and pressure. Improving the steam can be done using one or multiple ejectors, and they can connect in different configurations. In this study, we vary the ejector configuration and the geometric parameters of the ejectors to optimize the performance of the setup. We show that three ejectors are preferable to reach the goal of 1-2 bar and that other configurations might be valuable when lowering the pressure limit.
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Xiao, Hua. "Combustion of green fuels for power generation in gas turbine." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/111951/.
Full textAbstract:
The main objective of this thesis is to investigate the fundamental combustion process of ammonia-based fuels and the application on swirl-stabilised flames in the context of engineering type gas turbine combustion. The present study begins with a fundamental validation and mechanism reduction for chemical kinetics of ammonia/methane combustion. Different-sized reduced mechanisms of the well-known Konnov’s mechanism were compared at high-pressure conditions relevant to gas turbine devices. The reduced models can benefit the future simulation work with considerably less computational cost. Then characteristics of ignition delay time, laminar flame speed and emissions were obtained over a wide range of equivalence ratios and ammonia fractions. Prediction results showed a good potential of ammonia/methane to be used in gas turbine engines with relatively low emission. In the second part of this dissertation, in order to identify reaction mechanisms that can accurately represent ammonia/hydrogen kinetics at industrial conditions, various mechanisms were tested in terms of flame speed, combustion products and ignition delay against experimental data. It was preliminarily found that the Mathieu mechanism and Tian mechanism are the best suited for ammonia/hydrogen combustion chemistry under practical industrial conditions. Based on the Mathieu mechanism, an improved chemical mechanism was developed. Verification of the established model was quite satisfying, focusing particularly on elevated conditions which are encountered during gas turbine operation. Finally, a first assessment of the suitability of a chosen 70%NH3-30%H2 (%vol) blend was performed for utilisation within a gas turbine environment. It was found that stable flames can be produced with low NOx emissions at high equivalence ratios. Also, results showed that high inlet temperature conditions representative of real gas turbine conditions can significantly improve the combustion efficiency and reduce NOx emissions. A numerical gas turbine cycle calculation was performed indicating more research are required to enable higher efficiencies using ammonia/hydrogen.
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Hu, Yukun. "CO2 capture from oxy-fuel combustion power plants." Licentiate thesis, KTH, Energiprocesser, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48666.
Full textAbstract:
To mitigate the global greenhouse gases (GHGs) emissions, carbon dioxide (CO2) capture and storage (CCS) has the potential to play a significant role for reaching mitigation target. Oxy-fuel combustion is a promising technology for CO2 capture in power plants. Advantages compared to CCS with the conventional combustion technology are: high combustion efficiency, flue gas volume reduction, low fuel consumption, near zero CO2 emission, and less nitrogen oxides (NOx) formation can be reached simultaneously by using the oxy-fuel combustion technology. However, knowledge gaps relating to large scale coal based and natural gas based power plants with CO2 capture still exist, such as combustors and boilers operating at higher temperatures and design of CO2 turbines and compressors. To apply the oxy-fuel combustion technology on power plants, much work is focused on the fundamental and feasibility study regarding combustion characterization, process and system analysis, and economic evaluation etc. Further studies from system perspective point of view are highlighted, such as the impact of operating conditions on system performance and on advanced cycle integrated with oxy-fuel combustion for CO2 capture. In this thesis, the characterization for flue gas recycle (FGR) was theoretically derived based on mass balance of combustion reactions, and system modeling was conducted by using a process simulator, Aspen Plus. Important parameters such as FGR rate and ratio, flue gas composition, and electrical efficiency etc. were analyzed and discussed based on different operational conditions. An advanced evaporative gas turbine (EvGT) cycle with oxy-fuel combustion for CO2 capture was also studied. Based on economic indicators such as specific investment cost (SIC), cost of electricity (COE), and cost of CO2avoidance (COA), economic performance was evaluated and compared among various system configurations. The system configurations include an EvGT cycle power plant without CO2 capture, an EvGT cycle power plant with chemical absorption for CO2 capture, and a combined cycle power plant. The study shows that FGR ratio is of importance, which has impact not only on heat transfer but also on mass transfer in the oxy-coal combustion process. Significant reduction in the amount of flue gas can be achieved due to the flue gas recycling, particularly for the system with more prior upstream recycle options. Although the recycle options have almost no effect on FGR ratio, flue gas flow rate, and system electrical efficiency, FGR options have significant effects on flue gas compositions, especially the concentrations of CO2 and H2O, and heat exchanger duties. In addition, oxygen purity and water/gas ratio, respectively, have an optimum value for an EvGT cycle power plant with oxy-fuel combustion. Oxygen purity of 97 mol% and water/gas ratio of 0.133 can be considered as the optimum values for the studied system. For optional operating conditions of flue gas recycling, the exhaust gas recycled after condensing (dry recycle) results in about 5 percentage points higher electrical efficiency and about 45 % more cooling water consumption comparing with the exhaust gas recycled before condensing (wet recycle). The direct costs of EvGT cycle with oxy-fuel combustion are a little higher than the direct costs of EvGT cycle with chemical absorption. However, as plant size is larger than 60 MW, even though the EvGT cycle with oxy-fuel combustion has a higher COE than the EvGT cycle with chemical absorption, the EvGT cycle with oxy-fuel combustion has a lower COA. Further, compared with others studies of natural gas combined cycle (NGCC), the EvGT system has a lower COE and COA than the NGCC system no matter which CO2 capture technology is integrated.QC 20111123
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Fendt, Sebastian [Verfasser]. "Experimental Investigation of a Combined Biomass-to-Gas/ Power-to-Gas Concept for the Production of Synthetic Natural Gas (SNG) / Sebastian Fendt." München : Verlag Dr. Hut, 2020. http://d-nb.info/1219475491/34.
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Gibrael, Nemir, and Hamse Hassan. "HYDROGEN-FIRED GAS TURBINE FOR POWER GENERATION WITH EXHAUST GAS RECIRCULATION : Emission and economic evaluation of pure hydrogen compare to natural gas." Thesis, Mälardalens högskola, Framtidens energi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-42306.
Full textAbstract:
The member states of European Union aim to promote the reduction of harmful emissions. Emissions from combustion processes cause effects on human health and pose environmental issues, for example by increasing greenhouse effect. There are two ways to reduce emissions; one is to promote renewable energy sources and the other to utilize more effectively the available fossil fuels until a long-term solution is available. Hence, it is necessary to strive for CO2 mitigation technologies applied to fossil fuels. Low natural gas prices together with high energy efficiency have made gas turbines popular in the energy market. But, gas turbine fired with natural gas come along with emissions of CO2, NOx and CO. However, these disadvantages can be eliminated by using gas turbine with precombustion CO2 capture, separating carbon from the fuel by using fuel reforming process and feeding pure hydrogen as a fuel. Hydrogen fired gas turbines are used in two applications such as a gas turbine with pre-combustion CO2 capture and for renewable power plants where hydrogen is stored in case as a backup plan. Although the CO2 emissions are reduced in a hydrogen fired gas turbine with a pre-combustion CO2 capture, there are still several challenges such as high flame temperatures resulting in production of thermal NOx. This project suggests a method for application of hydrogen fired gas turbine, using exhaust gas recirculation to reduce flame temperature and thus reducing thermal NOx. A NOx emission model for a hydrogen-fired gas turbine was built from literature data and used to select the best operating conditions for the plant. In addition, the economic benefits of switching from natural gas to pure hydrogen are reported. For the techno-economic analysis, investment costs and operating costs were taken from the literature, and an economic model was developed. To provide sensitivity analysis for the techno-economic calculation, three cases were studied. Literature review was carried out on several journal articles and websites to gain understanding on hydrogen and natural gas fired gas turbines. Results showed that, in the current state, pure hydrogen has high delivery cost both in the US and Europe. While it’s easy to access natural gas at low cost, therefore in the current state gas turbine fired with natural gas are more profitable than hydrogen fired gas turbine. But, if targeted hydrogen prices are reached while fuel reforming process technology are developed in the coming future the hydrogen fired gas turbine will compete seriously with natural gas.
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Kandamby, Naminda Harisinghe. "Mathematical modelling of gasifier fuelled gas turbine combustors." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267305.
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Berry, David A. "Investigation of hot gas desulfurization utilizing a transport reactor." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=500.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains vi, 101 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 82-85).
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Anosike, Nnamdi Benedict. "Technoeconomic evaluation of flared natural gas reduction and energy recovery using gas-to-wire scheme." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8625.
Full textAbstract:
Most mature oil reservoirs or fields tend to perform below expectations, owing to
high level of associated gas production. This creates a sub-optimal performance
of the oil production surface facilities; increasing oil production specific
operating cost. In many scenarios oil companies flare/vent this gas. In addition
to oil production constraints, associated gas flaring and venting consists an
environmental disasters and economic waste. Significant steps are now being
devised to utilise associated gas using different exploitation techniques. Most of
the technologies requires large associated gas throughput.
However, small-scale associated gas resources and non-associated natural gas
reserves (commonly referred to as stranded gas or marginal field) remains
largely unexploited. Thus, the objective of this thesis is to evaluate techno-
economic of gas turbine engines for onsite electric power generation called gas-
to-wire (GTW) using the small-scaled associated gas resources. The range of
stranded flared associated gas and non-associated gas reserves considered is
around 10 billion to 1 trillion standard cubic feet undergoing production decline.
The gas turbine engines considered for power plant in this study are based on
simple cycle or combustion turbines. Simple cycle choice of power-plant is
conceived to meet certain flexibility in power plant capacity factor and
availability during production decline. In addition, it represents the basic power
plant module cable of being developed into other power plant types in future to
meet different local energy requirements.
This study developed a novel gas-to-wire techno-economic and risk analysis
framework, with capability for probabilistic uncertainty analysis using Monte
Carlo simulation (MCS) method. It comprises an iterative calculation of the
probabilistic recoverable reserves with decline module and power plant
thermodynamic performance module enabled by Turbomatch (an in-house
code) and Gas Turb® software coupled with economic risk modules with
@Risk® commercial software. This algorithm is a useful tool for simulating the
interaction between disrupted gas production profiles induced by production
decline and its effect on power plant techno-economic performance over
associated gas utilization economic life. Furthermore, a divestment and make-
up fuel protocol is proposed for management of gas turbine engine units to
mitigate economical underperformance of power plant regime experienced due
to production decline.
The results show that utilization of associated gas for onsite power generation is
a promising technology for converting waste to energy. Though, associated gas
composition can be significant to gas turbine performance but a typical Nigerian
associated gas considered is as good as a regular natural gas. The majority of
capital investment risk is associated with production decline both natural and
manmade. Finally, the rate of capital investment returns decreases with smaller
reserves.
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Bortot, Baptiste. "Gas for Balancing of Variable Power Generation : A Systemic Case Study." Thesis, KTH, Elektriska energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-144860.
Full textAbstract:
With the increasing share of variable renewable generation, balancing electric powersystems could become a major concern for system operators because of their variableand hardly predictable nature. However, gas technologies appear as a solutionto provide this flexibility, but the impacts on the gas power system have hardly beeninvestigated. In this thesis, consulting reports on the subject matter, regulator suggestions andgas-electricity interaction models in scientific literature are studied and four sourcesare identified to be used for balancing: linepack, storage facilities, liquefied natural gasand intraday gas supply from adjacent areas. Then, a gas-electricity model for flexibility supply is designed and three case studies are simulated in order to analyze bothgas and electric power systems’ behaviors. In these case studies, electricity generation,contribution of gas sources and costs are analysed. The study concludes that critical situations on gas market that can occur, e.g. incases of large variation in the net electricity demand and limited availability of linepackand storage facilities, the need of intraday modulation can exceed the possibilities toprovide for it. Then, gas cannot be supplied to power plants during peak periods, andmore gas than necessary is used during off-peak periods. The case studies also showthat day-ahead forecast errors in variable renewable generation can be handled mucheasier than variations by the gas system but leads to higher costs.
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Smith, P. J. "Predicting hot corrosion rates under coal fired combined cycle power plant conditions." Thesis, Cranfield University, 1994. http://dspace.lib.cranfield.ac.uk/handle/1826/10512.
Full textAbstract:
Type 11 hot corrosion has been identified as a major life limiting factor of gas turbine
components in the topping cycle of coal fired combined cycle power plant. Impurities in the
coal combustion gases provide the environmental contaminants necessary for type 11 hot
corrosion to occur.
It is the purpose of the present study to develop corrosion lifting models such that
corrosion rates and thus component lives in coal fired combined cycle plant gas turbines may
be accurately predicted thus minimising efficiency losses and plant downtime due to
corrosion related problems.
Type 11 hot corrosion has been shown to follow bi11lodal distributions which cannot
be modelled using the well known mathematical models. It has been shown that a
probabilistic approach to modelling is appropriate and that the Gumbel Type I extreme value
model of maxima can be used to model the maximum extreme corrosion data This is
appropriate as it is the maximum extreme corrosion which in life limiting in the plant gas
turbine.
Basic corrosion data has been generated through a series of laboratory hot corrosion
tests designed to simulate the ambient conditions within the plant gas turbine. The variables
having most influence on the corrosion process have been identified as ; temperature, thermal
cycling, alkali (Na + K) metal sulphate deposition rate, S02 and HCl in the ambient
atmosphere.
The corrosion models have been developed from this data which accurately predict
the type 11 hot corrosion rates observed in the coal fired gas turbine of a combined cycle
power plant .
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Wahlers, Kristen H. "Persuasive Power: Rhetoric of Risk in Sustainability in the Nuclear Power Lobby." Ohio University Honors Tutorial College / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1619214247007766.
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Monereo, Cuscó Oriol. "Gas sensors based on carbon nanofibers: a low power consumption approach." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/400488.
Full textAbstract:
Gas sensors can be found in many activities ranging from environment protection, risk prevention, agriculture and even in food, chemical, and petrochemical industries. There exist different technologies for gas sensors depending on the transduction mechanism: mass-sensitive, optical, calorimetric, magnetic, electrochemical and conductometric. In this work, conductometric (or resistive) gas sensors are studied. Conductometric devices base its operating principle on the variation of the electrical conductivity (resistivity) or conductance (resistance) of a reactive (active) material interacting with gas. A chemical reaction between the active material (surface or bulk) and the gas occurs. This reaction induces a variation on some electrical property of the material resulting in a change on the electrical signal (conductivity or resistivity of the active material) of the sensor. Therefore, the sensor material should be compatible with the mentioned properties above. A carbon based material was chosen to be the reactive compound for the conductometric sensors. This material, a specific type of carbon nanofibers (CNFs), shares some suitable properties with other trendy carbon based materials such as carbon nanotubes or graphene. Conductometric gas sensors usually are composed of two main parts: the already mentioned reactive material and the heater device. The heater is required in order to stabilize the temperature of operation and to activate a desired chemical reaction. Unfortunately, despite the efforts to improve the heater technology, this component is still the most power demanding part of the overall device. The here studied sensors have been characterized with a heater device, but also alternative energy sources and other sensing strategies have been tested in order to reduce the energy cost. Among these, the use of ultraviolet and visible light sources were tested in order to modulate the sensor properties. In addition, another non-common strategy was used to operate the sensor: the so called self-heating effect (or Joule effect). To obtain the electrical signal of a sensor, the reactive material have to be scanned, usually a current (or voltage) is applied to the sensor, then, the voltage (or current) is read. If the probing magnitude is increased, the power dissipation through the sensing material, and its temperature, also increases. Therefore, the sensor could be operated without a heater device with a considerable reduction of its power consumption. Moreover, the self-heating also allows reducing the fabrication complexity, as there is no need of the heater element.
In summary, the main objective of this work was to characterize the CNFs as a reactive material for conductometric sensors for low cost applications. First, the CNFs properties (electrical,
mechanical, response to light and gases) were screened with the aim to assess the applicability of the sensing material (O. Monereo et al., 2013, Flexible sensor based on carbon nanofibers with multifunctional sensing features). Then, the sensor was tested with the use of temperature modulation (S. Claramunt et al., 2013, Flexible gas sensor array with an embedded heater based on metal decorated carbon nanofibres). At this point, a more detailed characterization of the gas sensing properties with O2, H2O, NO2 and NH3 was conducted. Then, the use of continuous self-heating operation (O. Monereo et al., 2015, Self-heating effects in large arrangements of randomly oriented carbon nanofibers: Application to gas sensors) and pulsed self-heating application (O. Monereo et al., 2016, Self-heating in pulsed mode for signal quality improvement: application to carbon nanostructures-based sensors) were found to be efficient methodologies to modulate the sensing characteristics of sensor devices, based on large arrays of nanostructures. Among the benefits achieved, the sensor presented improvements on stability, specificity, the detection time modulation, all along the simplification of device fabrication and the reduction of the power consumption. Finally, the phenomenon of self-heating in carbon nanofibers and its origin was studied (O. Monereo et al., 2016, Localized self-heating in large arrays of 1D nanostructures). In addition, the use of ultraviolet and visible light as alternative energy sources was also assessed and compared with the self-heating operation. Finally, the applicability of self-heating was also tested in graphene based (reduced graphene oxide) and metal oxide based (ZnO) devices to test the applicability of self-heating in other relevant sensing materials.El objetivo principal de esta tesis es la caracterización de las nanofibras de carbono (CNFs) como material reactivo para sensores resistivos de gas para aplicaciones de bajo consumo. Primero, las propiedades eléctricas, mecánicas y respuesta a luz y gases de las CNFs fueron evaluadas para comprobar la aplicabilidad del material sensor (O. Monereo et al., 2013, Flexible sensor based on carbon nanofibers with multifunctional sensing features). Posteriormente, la respuesta del sensor a gases fue estudiada con modulación de temperatura (S. Claramunt et al., 2013, Flexible gas sensor array with an embedded heater based on metal decorated carbon nanofibres). En este punto, una caracteritzación más detallada de la respuesta del sensor a gases modulados con temperatura se realizó con O2, H2O, NO2 y NH3. A continuación, el uso de la metodología de auto-calentamiento continuo (O. Monereo et al., 2015, Self-heating effects in large arrangements of randomly oriented carbon nanofibers: Application to gas sensors) y pulsado (O. Monereo et al., 2016, Self-heating in pulsed mode for signal quality improvement: application to carbon nanostructures-based sensors) han sido probados como formas energéticamente eficientes para modular la respuesta de sensores basados en grandes matrices de CNFs. Entre los beneficios encontrados, consta una mejora de la estabilidad, especificidad, la modulación del tiempo de detección; todo añadiendo la simplificación de la fabricación. Finalmente, el origen del fenómeno de auto-calentamiento en CNFs fue estudiado en detalle (O. Monereo et al., 2016, Localized self-heating in large arrays of 1D nanostructures). Además, la aplicabilidad de la metodología fue también probada en nanotubos de carbono, óxido de grafeno reducido y nanohilos de óxido de zinc. Finalmente, el uso de luz ultraviolada y visible ha sido estudiado como a energías alternativas para la modulación de los sensores de gases de CNFs.
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Russ, Matthias. "Elaboration of Thermo-Economic Models of Solar Gas-Turbine Power Plants." Thesis, KTH, Energiteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-72483.
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Tsoudis, Evangelos. "Technoeconomic Environmental and Risk Analysis of Marine Gas Turbine Power Plants." Thesis, Cranfield University, 2008. http://hdl.handle.net/1826/3535.
Full textAbstract:
A novel generic Technoeconomic, Environmental and Risk Analysis (TERA)
computational method was developed for marine power plants that are composed of
existing or at preliminary design stage marine gas turbines. The method is composed
of several numerical models in order to realistically approach the life cycle operation
of a marine gas turbine power plant-according to the operational profile of the
platform marine vessel type-coupled to an integrated full electric propulsion system
and stochastically estimate the power plant’s life cycle net present cost. The
development of the TERA method led to the creation of an integrated computational
marine vessel operation environment which was given the name “Poseidon”.
The performance and exhaust emissions (nitric oxide, carbon monoxide, carbon
dioxide and unburned hydrocarbon) of five 25 Megawatt marine gas turbines of the
same technology level and design-point overhaul interval were simulated and
modelled in “Poseidon”. The exhaust emissions of the modelled gas turbines were
calibrated for two combustor technologies: conventional and dry-low emissions for
both distillate fuel and natural gas used as fuel. The marine gas turbines are: existing
simple cycle, novel twin-mode intercooled cycle, fictional intercooled cycle, fictional
recuperated cycle and partly based on an existing design, intercooled/recuperated
cycle. Three marine vessel types that require the same power plant output power and
configuration but they utilise different operational profiles were also realistically
modelled. The marine vessels are: Destroyer, RoPax fast ferry and LNG carrier. It
was assumed that the Destroyer’s and RoPax fast ferry’s power plants use distillates
fuel and the LNG carrier’s power plant uses compressed natural gas as fuel.
Three case studies defined by each of the marine vessels were performed in order to
investigate the economic feasibility of the advanced cycle gas turbine power plants in
comparison with the power plant composed by existing gas turbines, in a possible
future scenario were all four modelled exhaust emission quantities are accurately
measured and taxed. The investment on dry-low emissions combustor technology was
also investigated as part of each case study. Both technical and economic input
datasets are realistic. Due to time restrains the LNG carrier case study features only
the intercooled/recuperated gas turbine power plant. Obtained results are presented
and discussed separately for each case study.
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Kennaugh, Richard Juan. "Stability of a plasma in a noble gas magnetohydrodynamic power generator." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335847.
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Kaldahl, Jonas Aase, and Kristoffer Ingebrigtsen. "Sequential investment in gas fired power plants : A real options analysis." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for industriell økonomi og teknologiledelse, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25908.
Full textAbstract:
This paper presents an empirical analysis of the real options to postpone and cancel sequential investments with time-to-build. Utilizing generator level data that to the best of our knowledge is unique in scope and detail, we look at investments in gas fired combustion and combined cycle generators. We find strong evidence of real option effects. Regulatory uncertainty and profit uncertainty increases the probability of companies postponing and canceling investments. Firms postponing during times of uncertainty is as expected from theory; firms canceling under these conditions is somewhat more surprising.
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Tanaka, Shinji S. M. Massachusetts Institute of Technology. "Acoustic and thermal packaging of small gas turbines for portable power." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51648.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.Includes bibliographical references (p. 201-203).
To meet the increasing demand for advanced portable power units, for example for use in personal electronics and robotics, a number of studies have focused on portable small gas turbines. This research is concerned with gas turbine generator units in the 1 kW range. The compact and small-scale architecture of the portable gas turbine engine poses major challenges in the acoustic treatment that is required to attenuate the broadband and tonal noise of the high-speed turbomachinery. The challenge in the thermal management is the relatively large required cooling mass flow and the short flow mixing length, constrained by package size considerations. The objective is to conceive a proof-of-concept engine package with exhaust temperatures of 60 °C and a noise signature below 50 dBA at a distance of 7 m. Various liner materials and configurations were investigated in an anechoic chamber using a modular silencer test rig. Acoustic liners based on porous fiber material were developed for both cold intake and hot exhaust gas silencers to reduce the broadband noise. The source noise simulations combined with the measured silencer noise reduction show noise levels below 50 dBA in all directions. A parametric silencer configuration study was carried out to determine the trade-off between liner volume, surface area, and noise reduction. The liner material was demonstrated to withstand hot gas conditions at 700 °C.
(cont.) A mixer/ejector based cooling scheme was proposed and experimentally investigated using vortex generator rings and multi-walled ejectors to enhance the mixing. Although the augmentations achieved a satisfactory mass flow ratio of 16.8:1, hot spots still exist at the exit of the relatively long mixer duct due to the high area-ratio of the ejector configuration. It was concluded that implementation of the scheme into the package is not practical. To overcome this mixing challenge, an alternative cooling scheme was conceived. An inverted dilution liner mixes hot core gas flowing radially through a perforated cylinder with cold fan air. The mixing length is reduced due to jet induced streamwise vortices. The performance of the device was investigated using three-dimensional computational fluid dynamics simulations, which demonstrated improved mixing and uniform, low temperatures of less than 70 °C at the mixer exit. Noise reduction and flow mixing guidelines are established together with a concept package configuration, generally applicable to small scale gas turbine devices.
by Shinji Tanaka.
S.M.