Home About us Contact
|
Home About us Contact | ||
|
|
||
Power Plants (power + plant)
Kinds of Power Plants Selected AbstractsSimulation of the Carbonate Looping Process for Post-Combustion CO2 Capture from a Coal-Fired Power PlantCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2009J. Ströhle Abstract The present contribution focuses on the carbonate looping process, i.e., post-combustion CO2 capture by means of CaO containing solid sorbents in a system of two circulating fluidized bed reactors. Material and energy balances were performed using the ASPEN PLUSTM software. Two different modeling approaches are applied to the carbonator. First, the entire active fraction of CaO is assumed to be converted; second, the CO2 absorption efficiency in the circulating fluidized bed is calculated using an analytical 1D model for fast fluidization. The absorption of SO2 by CaO is taken into account. The overall plant efficiency depends on the mass flows of fresh limestone and circulating CaO. The process is shown to be economically feasible, having low energy penalties in comparison with other CO2 capture technologies and it seems to be suited for retro-fitting existing power plants. [source] Environmental Guidelines for Power Plants in India and Other NationsENVIRONMENTAL QUALITY MANAGEMENT, Issue 1 2001Subrato Sinha The emissions guidelines for power plants in India are comparable to those of many other developed and developing nations, and in some cases are more stringent. But India's environmental impact assessment and enforcement practices need to be improved. © 2001 John Wiley & Sons, Inc. [source] Water Use by Thermoelectric Power Plants in the United States,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2007Xiaoying Yang Abstract:, Thermoelectric power generation is responsible for the largest annual volume of water withdrawals in the United States although it is only a distant third after irrigation and industrial sectors in consumptive use. The substantial water withdrawals by thermoelectric power plants can have significant impacts on local surface and ground water sources, especially in arid regions. However, there are few studies of the determinants of water use in thermoelectric generation. Analysis of thermoelectric water use data in existing steam thermoelectric power plants shows that there is wide variability in unitary thermoelectric water use (in cubic decimeters per 1 kWh) within and among different types of cooling systems. Multiple-regression models of unit thermoelectric water use were developed to identify significant determinants of unit thermoelectric water use. The high variability of unit usage rates indicates that there is a significant potential for water conservation in existing thermoelectric power plants. [source] Monopilegründungen von Offshore-Windenergieanlagen , Zum Ansatz der BettungBAUTECHNIK, Issue 1 2005Jürgen Grabe Univ.-Prof. Bei der Gründung von Offshore-Windenergieanlagen mit Monopiles stellt die große Momenten- und Horizontalkraftbelastung und deren zyklisches Auftreten eine besondere Herausforderung an die Prognose der Pfahlverformungen dar. Für ein System mit beispielhaften Abmessungen, Baugrundverhältnissen und Belastungen werden die konventionellen Verfahren zur Berechnung der horizontalen Pfahltragfähigkeit und -verformung, Bettungsmodulverfahren und API-Verfahren, mit den Ergebnissen einer 3D-FE-Analyse verglichen. Es zeigt sich, daß die konventionellen Verfahren für die Prognose der Verformungen im Gebrauchszustand, also deutlich unterhalb der Grenzlast, für dieses Beispiel unzureichend sind. Die Verteilung des Bettungsmoduls über die Tiefe wird mit keinem der Verfahren zutreffend abgebildet. Des weiteren wird die Veränderung des Bettungsmoduls über mehrere Zyklen für Schwell- und Wechselbelastungen untersucht. Vor allem bei einer Schwellast wird der auf den Ausgangszustand bezogene Bettungsmodul mit jedem Zyklus verändert. Die Verschiebung des Pfahlkopfs steigt auch nach 20 Belastungszyklen noch an. Der aus der ödometrischen Steifigkeit des Bodens abgeleitete Bettungsmodul ist zur Prognose der Pfahlverformungen insbesondere bei zyklischer Last fragwürdig. Hierfür besteht insbesondere in Anbetracht der geplanten Investitionen erheblicher Forschungsbedarf. Monopile foundations for Offshore-Wind Power Plants , approach of subgrade reaction. The large moments and horizontal forces and their cyclic occurrence represent a special challenge to the prognosis of the deformations of Monopiles as a foundation of offshore wind energy plants. The conventional procedures for the computation of the horizontal pile bearing capacity and deformation, subgrade reaction procedure and API procedure, are compared with the results of a 3D-FE analysis for a system with exemplary dimensions, soil conditions and loads. It is shown that the conventional procedures for the prognosis of the deformations in the serviceability limit state, thus clearly underneath the maximum load, for this example are insufficient. The distribution of the subgrade reaction modulus over the depth is sufficiently approximated with none of these procedures. Moreover the change of the subgrade reaction modulus is investigated for several cycles swelling and alternated loads. The modulus of subgrade reaction, referred to the initial pile position, changes especially under swelling loads for each loading cycle. The displacement of the pilehead still increases after 20 cycles. The modulus of subgrade reaction derived from the oedometric soil stiffness does not produce an accurate prognosis of the pile deformation particularly for cyclic loads. For this purpose further investigations are necessary. [source] Teilsicherheitsfaktoren für die Berechnung von GroßkraftwerkenBETON- UND STAHLBETONBAU, Issue 7 2010Simon Glowienka Dr.-Ing. Normen, Vorschriften, Richtlinien; Berechnungs- und Bemessungsverfahren Abstract Die Baustrukturen von Großkraftwerken werden in Deutschland u. a. auf Basis der VGB-Richtlinie R 602 U berechnet und bemessen. In dieser Richtlinie sind unter Berücksichtigung der Besonderheiten des Großkraftwerksbaus Einwirkungen und Teilsicherheitsfaktoren definiert. Während die Lasten auf diese Randbedingungen abgestimmt wurden, hat man die Teilsicherheitsfaktoren auf der Lastseite aus der DIN 1055-100 entnommen und lediglich die Kombinationsbeiwerte angepasst. Diese Sicherheitsbeiwerte tragen jedoch den speziellen Randbedingungen eines Kraftwerks oder Schwerindustriebaus nur bedingt Rechnung. Im Rahmen des Beitrags werden die Teilsicherheitsbeiwerte auf der Einwirkungsseite , insbesondere für das Konstruktionseigengewicht , für die Bemessung von Stahlbetonteilen vor diesem Hintergrund kritisch diskutiert und ein optimierter, wissenschaftlich abgesicherter Vorschlag unterbreitet. Partial Safety Factors for the Design of Power Plants In Germany power plants are designed in accordance to VGB regulation R 602 U. In this code load actions and partial safety factors are applied taking the special characteristics of power plants into consideration. The actions are defined regarding these circumstances, however the safety coefficients are assumed according to DIN 1055-100 and only the combination coefficients are adjusted. However it has to be recognized that the partial safety factors in DIN 1055-100 are calibrated for building constructions and thus do not consider the specialities of power plants in an adequate manner. In this paper the partial safety factors for the design of power plants and other heavy industry buildings are discussed for structural concrete elements and a scientific based optimized approach for the safety factor for dead load is presented. [source] Grundlagen des Lebensdauermanagements im KraftwerksbauBETON- UND STAHLBETONBAU, Issue 7 2010Tobias Pfister Dr.-Ing. Allgemeines; Bauwerkserhaltung/Sanierung; Bauwerksüberwachung Abstract Der Begriff des "Lebensdauermanagements" rückt im Kraftwerksbau auch bei der Planung von Neubauten verstärkt in das Blickfeld der Betreiber. Darüber hinaus werden für Bestandsbauwerke unter dem Einfluss von Laufzeitverlängerungen Maßnahmen erforderlich, die die Restlebensdauer zuverlässig bewerten und sicherstellen können. Der vorliegende Beitrag zeichnet die rechtlichen Rahmenbedingungen nach, aus denen sich das Erfordernis eines aktiven Lebensdauermanagements ergibt und stellt die Vorgehensweise und grundlegenden Elemente einer derartigen begleitenden Überwachungsstrategie dar. Fundamentals of Lifetime Management in Power Plants The concept of "lifetime management" moves more and more into the focus of power plant owners, also in the context of new constructions. Additionally, for existing buildings there is a demand for methods, which are able to estimate the remaining lifetime in a reliable way. The present contribution collocates the legal general conditions, which lead to a requirement of an active lifetime management, and presents the procedure and basic elements of such an accompanying inspection strategy. [source] Cycle analysis of low and high H2 utilization SOFCs/gas turbine combined cycle for CO2 recoveryELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 10 2008Takuya Taniuchi Abstract Global warming is mainly caused by CO2 emission from thermal power plants, which burn fossil fuel with air. One of the countermeasure technologies to prevent global warming is CO2 recovery from combustion flue gas and the sequestration of CO2 underground or in the ocean. SOFC and other fuel cells can produce high-concentration CO2, because the reformed fuel gas reacts with oxygen electrochemically without being mixed with air, or diluted by N2. Thus, we propose to operate the multistage SOFCs under high utilization of reformed fuel for obtaining high-concentration CO2. In this report, we have estimated the multistage SOFCs' performance considering H2 diffusion and the combined cycle efficiency of multistage SOFC/gas turbine/CO2 recovery power plant. The power generation efficiency of our CO2 recovery combined cycle is 68.5% and the efficiency of conventional SOFC/GT cycle is 57.8% including the CO2 recovery amine process. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(10): 38,45, 2008; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecj.10165 [source] Incidence and impact of axial malformations in larval bullfrogs (Rana catesbeiana) developing in sites polluted by a coal-burning power plantENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2000William A. Hopkins Abstract Amphibian malformations have recently received much attention from the scientific community, but few studies have provided evidence linking environmental pollution to larval amphibian malformations in the field. We document an increased incidence of axial malformations in bullfrog larvae (Rana catesbeiana) inhabiting two sites contaminated with coal combustion wastes. In the polluted sites, 18 and 37% of larvae exhibited lateral curvatures of the spine, whereas zero and 4% of larvae from two reference sites had similar malformations. Larvae from the most heavily polluted site had significantly higher tissue concentrations of potentially toxic trace elements, including As, Cd, Se, Cu, Cr, and V, compared with conspecifics from the reference sites. In addition, malformed larvae from the most contaminated site had decreased swimming speeds compared with those of normal larvae from the same site. We hypothesize that the complex mixture of contaminants produced by coal combustion is responsible for the high incidence of malformations and associated effects on swimming performance. [source] Expert system for nuclear power plant accident diagnosis using a fuzzy inference methodEXPERT SYSTEMS, Issue 4 2002rey Lee Huge and complex systems such as nuclear power generating stations are likely to cause the operators to make operational mistakes for a variety of inexplicable reasons and to produce ambiguous and complicated symptoms in the case of an emergency. Therefore, a safety protection system to assist the operators in making proper decisions within a limited time is required. In this paper, we develop a reliable and improved diagnosis system using the fuzzy inference method so that the system can classify accident symptoms and identify the most probable causes of accidents in order for appropriate actions to be taken to mitigate the consequences. In the computer simulation, the proposed system proved to be able to classify accident types within only 20,30 s. Therefore, the corresponding operation guidelines can be determined in a very short time to put the nuclear power plant in a safe state immediately after the accident. [source] Tapovan-Vishnugad hydroelectric power project , experience with TBM excavation under high rock cover / . Tapovan-Vishnugad Wasserkraftwerk , Erfahrungen mit TBM-Vortrieb bei hoher ÜberlagerungGEOMECHANICS AND TUNNELLING, Issue 5 2010Johann Brandl Mechanised tunnelling - Maschineller Vortrieb; Hydro power plants - Wasserkraftanlagen Abstract NTPC Ltd. of India is presently constructing the 520 MW (4 x 30 MW) Tapovan-Vishnugad hydroelectric power plant in Uttarakhand in the Himalayas. As part of this project, an approximately 12.1 km head race tunnel (HRT) is to be constructed, of which approximately 8.6 km are being excavated by DS-TBM with an excavation diameter of 6.575 m. Construction of this HRT has been awarded to a Joint Venture (JV) of Larsen, Toubro Ltd., India, and Alpine, Austria. Geoconsult ZT GmbH is acting as a Consultant to NTPC Ltd. for the TBM part of the HRT. The overburden above the tunnel is up to 1, 100 m with the result that knowledge of the geology along the HRT alignment could only be based on projections made from surface exposures available in the area. Basically, the ground consists of jointed quartzite, gneiss and schist. Excavation of the HRT started in October 2008 and excavation rates of over 500 m per month were achieved in November 2009. However, in December 2009 the TBM encountered a fault zone along with high-pressure water inflow and became trapped. This paper outlines the present status of HRT construction and describes in particular the difficulties encountered during TBM excavation in fault zones with large high-pressure water inflows and how these problems are being dealt with. Die indische Firma NTPC Ltd. errichtet derzeit das 520 MW (4 x 130 MW) Tapovan-Vishnugad Wasserkraftwerk in Uttarakhand, Himalaya. Als Teil dieses Projekts wird ein ungefähr 12,1 km langer Triebwasserstollen (TWS) errichtet, wobei rund 8,6 km davon mittels einer DS-TBM mit einem Ausbruchdurchmesser von 6.575 m aufgefahren werden. Der Bau dieses Triebwasserstollens wurde an die Arbeitsgemeinschaft Larsen, Toubro Ltd., Indien, und Alpine, Österreich vergeben. Geoconsult ZT GmbH fungiert als Berater von NTPC Ltd. für den TBM-Teil des TWS. Aufgrund der Überlagerung des Tunnels von bis zu 1,100 m konnte die Geologie entlang des Triebwasserstollens nur durch Projektion von vorhandenen Oberflächenaufschlüssen aus der Umgebung bestimmt werden. Das Gebirge besteht hauptsächlich aus geklüftetem Quarzit, Gneis und Schiefer. Der Ausbruch des TWS begann im Oktober 2008. Im November 2009 wurde eine Vortriebsgeschwindigkeit von über 500 m pro Monat erreicht. Im Dezember 2009 jedoch fuhr die TBM eine Störzone mit einem Hochdruckwassereinbruch an, wodurch die TBM stecken blieb. Dieser Artikel skizziert den derzeitigen Stand des TWS und legt besonderes Augenmerk auf die Schwierigkeiten beim Auffahren der Störzone inklusive Hochdruckwassereinbruch mit einer TBM. Darüber hinaus wird gezeigt, wie sich die auftretenden Probleme lösen lassen. [source] Application of decentralized control for remote power system stabilization by installing renewable energy power plantIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 5 2008Tomonobu Senjyu Senior Member Abstract The generating power of wind turbines varies in proportion to the cube of wind speed, hence, they cannot supply constant power and this causes fluctuations in frequency and voltage. This article presents a methodology for controlling grid frequency, hydrogen volume, and terminal bus voltage. This system consists of diesel generators, wind turbines, and load. Aqua electrolyzer and fuel cells are introduced in order to control grid frequency, voltage, and hydrogen volume. By applying H, control, frequency, voltage fluctuation, and hydrogen volume, controls are achieved. H, decentralized controllers are designed and installed for diesel generators, aqua electrolyzers, and fuel cells in series. In order to verify the effectiveness of the suggested system, MATLAB/SIMULINK is used for simulation. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Sliding,window neural state estimation in a power plant heater lineINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2001A. Alessandri Abstract The state estimation problem for a section of a real power plant is addressed by means of a recently proposed sliding-window neural state estimator. The complexity and the nonlinearity of the considered application prevent us from successfully using standard techniques as Kalman filtering. The statistics of the distribution of the initial state and of noises are assumed to be unknown and the estimator is designed by minimizing a given generalized least-squares cost function. The following approximations are enforced: (i) the state estimator is a finite-memory one, (ii) the estimation functions are given fixed structures in which a certain number of parameters have to be optimized (multilayer feedforward neural networks are chosen from among various possible nonlinear approximators), (iii) the algorithms for optimizing the parameters (i.e., the network weights) rely on a stochastic approximation. Extensive simulation results on a complex model of a part of a real power plant are reported to compare the behaviour of the proposed estimator with the extended Kalman filter. Copyright © 2001 John Wiley & Sons, Ltd. [source] Geothermal-based hydrogen production using thermochemical and hybrid cycles: A review and analysisINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2010M. Tolga Balta Abstract Geothermal-based hydrogen production, which basically uses geothermal energy for hydrogen production, appears to be an environmentally conscious and sustainable option for the countries with abundant geothermal energy resources. In this study, four potential methods are identified and proposed for geothermal-based hydrogen production, namely: (i) direct production of hydrogen from the geothermal steam, (ii) through conventional water electrolysis using the electricity generated through geothermal power plant, (iii) by using both geothermal heat and electricity for high temperature steam electrolysis and/or hybrid processes, and (iv) by using the heat available from geothermal resource in thermochemical processes. Nowadays, most researches are focused on high-temperature electrolysis and thermochemical processes. Here we essentially discuss some potential low-temperature thermochemical and hybrid cycles for geothermal-based hydrogen production, due to their wider practicality, and examine them as a sustainable option for hydrogen production using geothermal heat. We also assess their thermodynamic performance through energy and exergy efficiencies. The results show that these cycles have good potential and attractive overall system efficiencies over 50% based on a complete reaction approach. The copper-chlorine cycle is identified as a highly promising cycle for geothermal-hydrogen production. Copyright © 2009 John Wiley & Sons, Ltd. [source] Energy, exergy and exergoeconomic analysis of a steam power plant: A case studyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2009Mohammad Ameri Abstract The objective of this paper is to perform the energy, exergy and exergoeconomic analysis for the Hamedan steam power plant. In the first part of the paper, the exergy destruction and exergy loss of each component of this power plant is estimated. Moreover, the effects of the load variations and ambient temperature are calculated in order to obtain a good insight into this analysis. The exergy efficiencies of the boiler, turbine, pump, heaters and the condenser are estimated at different ambient temperatures. The results show that energy losses have mainly occurred in the condenser where 306.9,MW is lost to the environment while only 67.63,MW has been lost from the boiler. Nevertheless, the irreversibility rate of the boiler is higher than the irreversibility rates of the other components. It is due to the fact that the combustion reaction and its high temperature are the most significant sources of exergy destruction in the boiler system, which can be reduced by preheating the combustion air and reducing the air,fuel ratio. When the ambient temperature is increased from 5 to 24°C, the irreversibility rate of the boiler, turbine, feed water heaters, pumps and the total irreversibility rate of the plant are increased. In addition, as the load varies from 125 to 250,MW (i.e. full load) the exergy efficiency of the boiler and turbine, condenser and heaters are increased due to the fact that the power plant is designed for the full load. In the second part of the paper, the exergoeconomic analysis is done for each component of the power plant in order to calculate the cost of exergy destruction. The results show that the boiler has the highest cost of exergy destruction. In addition, an optimization procedure is developed for that power plant. The results show that by considering the decision variables, the cost of exergy destruction and purchase can be decreased by almost 17.11%. Copyright © 2008 John Wiley & Sons, Ltd. [source] Exergoeconomic optimization of a 1000,MW light water reactor power generation systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2009Hoseyn Sayyaadi Abstract A typical 1000,MW pressurized water reactor nuclear power plant is considered for optimization. The thermodynamic modeling is performed based on the energy and exergy analysis, while an economic model is developed according to the total revenue requirement method. The objective function based on the exergoeconomic analysis is obtained. The exergoeconomic optimization process with 10 decision variables is performed using a hybrid stochastic/deterministic search algorithm namely as genetic algorithm. The results that are obtained using optimization process are compared with the base case system and the discussion is presented. Copyright © 2009 John Wiley & Sons, Ltd. [source] Cost numerical optimization of the triple-pressure steam-reheat gas-reheat gas-recuperated combined power cycle that uses steam for cooling the first GTINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2008A. M. Bassily Abstract Optimization is an important method for improving the efficiency and power of the combined cycle. In this paper, the triple-pressure steam-reheat gas-reheat gas-recuperated combined cycle that uses steam for cooling the first gas turbine (the regular steam-cooled cycle) was optimized relative to its operating parameters. The optimized cycle generates more power and consumes more fuel than the regular steam-cooled cycle. An objective function of the net additional revenue (the saving of the optimization process) was defined in terms of the revenue of the additional generated power and the costs of replacing the heat recovery steam generator (HRSG) and the costs of the additional operation and maintenance, installation, and fuel. Constraints were set on many operating parameters such as air compression ratio, the minimum temperature difference for pinch points (,Tppm), the dryness fraction at steam turbine outlet, and stack temperature. The net additional revenue and cycle efficiency were optimized at 11 different maximum values of turbine inlet temperature (TIT) using two different methods: the direct search and the variable metric. The optima were found at the boundaries of many constraints such as the maximum values of air compression ratio, turbine outlet temperature (TOT), and the minimum value of stack temperature. The performance of the optimized cycles was compared with that for the regular steam-cooled cycle. The results indicate that the optimized cycles are 1.7,1.8 percentage points higher in efficiency and 4.4,7.1% higher in total specific work than the regular steam-cooled cycle when all cycles are compared at the same values of TIT and ,Tppm. Optimizing the net additional revenue could result in an annual saving of 21 million U.S. dollars for a 439,MW power plant. Increasing the maximum TOT to 1000°C and replacing the stainless steel recuperator heat exchanger of the optimized cycle with a super-alloys-recuperated heat exchanger could result in an additional efficiency increase of 1.1 percentage point and a specific work increase of 4.8,7.1%. The optimized cycles were about 3.3 percentage points higher in efficiency than the most efficient commercially available H-system combined cycle when compared at the same value of TIT. Copyright © 2008 John Wiley & Sons, Ltd. [source] Natural gas internal combustion engine hybrid passenger vehicleINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2008S. Wright Abstract The implementation of hybrid electric vehicles powered with alternative fuels is critical in reducing national dependence on imported crude oil, addressing the detrimental environmental impact of increasing petroleum usage worldwide, and sustaining the national economy. The question is not whether changes should be made, but instead centers on identifying pathways that will lead to the greatest environmental and economic benefits. To avoid misuse of limited infrastructure investment, the objective of this research is to consider a broad range of relevant factors to determine desirable power plant,fuel combinations for hybrid electric vehicles. In the long term, fuel cells may dominate this application, but at least in the short term, proton exchange membrane fuel cells (PEMFCs) will not likely offer immediate substantial benefit over internal combustion (IC) engines. Environmentally friendly operation of the PEMFC results partly due to low-temperature operation but primarily due to the requirement of a clean fuel, hydrogen. In addition, the differential benefits from power plant choice can be overshadowed by the advantages obtained from hybrid electric vehicle technology and alternative fuels. Consequently, the fuel flexibility of IC engines provides an advantage over the relatively fuel inflexible PEMFC. The methane/hythane IC engine hybrid option, as developed and presented here, is a promising pathway that avoids the barriers encountered with conventional non-hybrid natural gas vehicles, namely range, power and fueling infrastructure difficulties. Dynamometer testing of the natural gas hybrid prototype on the certification FTP-72 duty cycle revealed very low emissions and mileage greater than 33 miles per gallon gasoline equivalent. This hybrid option utilizes a domestic, cost-effective fuel with renewable sources. With multi-fuel capability (methane, hythane and gasoline) it is also designed for use within the emerging hydrogen market. This hybrid option offers reliability and cost-effective technology with immediate wide spread market availability. Copyright © 2007 John Wiley & Sons, Ltd. [source] Analysis and cost optimization of the triple-pressure steam-reheat gas-reheat gas-recuperated combined power cycleINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2008A. M. Bassily Abstract Increasing the inlet temperature of gas turbine (TIT) and optimization are important methods for improving the efficiency and power of the combined cycle. In this paper, the triple-pressure steam-reheat gas-reheat recuperated combined cycle (the Regular Gas-Reheat cycle) was optimized relative to its operating parameters, including the temperature differences for pinch points (,TPP). The optimized triple-pressure steam-reheat gas-reheat recuperated combined cycle (the Optimized cycle) had much lower ,TPP than that for the Regular Gas-Reheat cycle so that the area of heat transfer of the heat recovery steam generator (HRSG) of the Optimized cycle had to be increased to keep the same rate of heat transfer. For the same mass flow rate of air, the Optimized cycle generates more power and consumes more fuel than the Regular Gas-Reheat cycle. An objective function of the net additional revenue (the saving of the optimization process) was defined in terms of the revenue of the additional generated power and the costs of replacing the HRSG and the additional fuel. Constraints were set on many operating parameters such as the minimum temperature difference for pinch points (,TPPm), the steam turbines inlet temperatures and pressures, and the dryness fraction at steam turbine outlet. The net additional revenue was optimized at 11 different maximum values of TIT using two different methods: the direct search and variable metric. The performance of the Optimized cycle was compared with that for the Regular Gas-Reheat cycle and the triple-pressure steam-reheat gas-reheat recuperated reduced-irreversibility combined cycle (the Reduced-Irreversibility cycle). The results indicate that the Optimized cycle is 0.17,0.35 percentage point higher in efficiency and 5.3,6.8% higher in specific work than the Reduced-Irreversibility cycle, which is 2.84,2.91 percentage points higher in efficiency and 4.7% higher in specific work than the Regular Gas-Reheat cycle when all cycles are compared at the same values of TIT and ,TPPm. Optimizing the net additional revenue could result in an annual saving of 33.7 million US dollars for a 481 MW power plant. The Optimized cycle was 3.62 percentage points higher in efficiency than the most efficient commercially available H-system combined cycle when compared at the same value of TIT. Copyright © 2007 John Wiley & Sons, Ltd. [source] Comparison of evaporative inlet air cooling systems to enhance the gas turbine generated powerINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2007Mohammad Ameri Abstract The gas turbine performance is highly sensitive to the compressor inlet temperature. The output of gas turbine falls to a value that is less than the rated output under high temperature conditions. In fact increase in inlet air temperature by 1°C will decrease the output power by 0.7% approximately. The solution of this problem is very important because the peak demand season also happens in the summer. One of the convenient methods of inlet air cooling is evaporating cooling which is appropriate for warm and dry weather. As most of the gas turbines in Iran are installed in such ambient conditions regions, therefore this method can be used to enhance the performance of the gas turbines. In this paper, an overview of technical and economic comparison of media system and fog system is given. The performance test results show that the mean output power of Frame-9 gas turbines is increased by 11 MW (14.5%) by the application of media cooling system in Fars power plant and 8.1 MW (8.9%) and 9.5 MW (11%) by the application of fog cooling system in Ghom and Shahid Rajaie power plants, respectively. The total enhanced power generation in the summer of 2004 was 2970, 1701 and 1340 MWh for the Fars, Ghom and Shahid Rajaie power plants, respectively. The economical studies show that the payback periods are estimated to be around 2 and 3 years for fog and media systems, respectively. This study has shown that both methods are suitable for the dry and hot areas for gas turbine power augmentation. Copyright © 2007 John Wiley & Sons, Ltd. [source] Transient thermal modelling of heat recovery steam generators in combined cycle power plantsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2007Sepehr Sanaye Abstract Heat recovery steam generator (HRSG) is a major component of a combined cycle power plant (CCPP). This equipment is particularly subject to severe thermal stress especially during cold start-up period. Hence, it is important to predict the operational parameters of HRSGs such as temperature of steam, water, hot gas and tube metal of heating elements as well as pressure change in drums during transient and steady-state operation. These parameters may be used for estimating thermal and mechanical stresses which are important in HRSG design and operation. In this paper, the results of a developed thermal model for predicting the working conditions of HRSG elements during transient and steady-state operations are reported. The model is capable of analysing arbitrary number of pressure levels and any number of elements such as superheater, evaporator, economizer, deaerator, desuperheater, reheater, as well as duct burners. To assess the correct performance of the developed model two kinds of data verification were performed. In the first kind of data verification, the program output was compared with the measured data collected from a cold start-up of an HRSG at Tehran CCPP. The variations of gas, water/steam and metal temperatures at various sections of HRSG, and pressure in drums were among the studied parameters. Mean differences of about 3.8% for temperature and about 9.2% for pressure were observed in this data comparison. In the second kind of data verification, the steady-state numerical output of the model was checked with the output of the well-known commercial software. An average difference of about 1.5% was found between the two latter groups of data. Copyright © 2007 John Wiley & Sons, Ltd. [source] Exergy analysis of a coal-based 210 MW thermal power plantINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2007S. Sengupta Abstract In the present work, exergy analysis of a coal-based thermal power plant is done using the design data from a 210 MW thermal power plant under operation in India. The entire plant cycle is split up into three zones for the analysis: (1) only the turbo-generator with its inlets and outlets, (2) turbo-generator, condenser, feed pumps and the regenerative heaters, (3) the entire cycle with boiler, turbo-generator, condenser, feed pumps, regenerative heaters and the plant auxiliaries. It helps to find out the contributions of different parts of the plant towards exergy destruction. The exergy efficiency is calculated using the operating data from the plant at different conditions, viz. at different loads, different condenser pressures, with and without regenerative heaters and with different settings of the turbine governing. The load variation is studied with the data at 100, 75, 60 and 40% of full load. Effects of two different condenser pressures, i.e. 76 and 89 mmHg (abs.), are studied. Effect of regeneration on exergy efficiency is studied by successively removing the high pressure regenerative heaters out of operation. The turbine governing system has been kept at constant pressure and sliding pressure modes to study their effects. It is observed that the major source of irreversibility in the power cycle is the boiler, which contributes to an exergy destruction of the order of 60%. Part load operation increases the irreversibilities in the cycle and the effect is more pronounced with the reduction of the load. Increase in the condenser back pressure decreases the exergy efficiency. Successive withdrawal of the high pressure heaters show a gradual increment in the exergy efficiency for the control volume excluding the boiler, while a decrease in exergy efficiency when the whole plant including the boiler is considered. Keeping the main steam pressure before the turbine control valves in sliding mode improves the exergy efficiencies in case of part load operation. Copyright © 2006 John Wiley & Sons, Ltd. [source] Analytical and numerical investigation of the solar chimney power plant systemsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2006Ming Tingzhen Abstract There is a surge in the use of the solar chimney power plant in the recent years which accomplishes the task of converting solar energy into kinetic energy. As the existing models are insufficient to accurately describe the mechanism, a more comprehensive model is advanced in this paper to evaluate the performance of a solar chimney power plant system, in which the effects of various parameters on the relative static pressure, driving force, power output and efficiency have been further investigated. Using the solar chimney prototype in Manzanares, Spain, as a practical example, the numerical studies are performed to explore the geometric modifications on the system performance, which show reasonable agreement with the analytical model. Copyright © 2005 John Wiley & Sons, Ltd. [source] An economic and environmental assessment of biomass utilization in lignite-fired power plants of GreeceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2006P. Grammelis Abstract The environmental and socio-economic impacts of biomass utilization by co-firing with brown coal in an existing thermoelectric unit in Greece or through its pure combustion in a new plant were studied and evaluated in this work. The 125 MWe lignite-fired power plant in Ptolemais Power Station (Western Macedonia) was used as reference system. The environmental benefits of the alternative biomass exploitation options were quantified based on the life cycle assessment methodology, as established by SETAC, while the BIOSEM technique was used to carry out socio-economic calculations. The obtained results showed clear environmental benefits of both biomass utilization alternatives in comparison with the reference system. In addition, co-firing biomass with lignite in an existing unit outperforms the combustion of biomass exclusively in a new plant, since it exhibits a better environmental performance and it is a low risk investment with immediate benefits. A biomass combustion unit requires a considerably higher capital investment and its benefits are more evident in the long run. Copyright © 2005 John Wiley & Sons, Ltd. [source] Energy,exergy analysis and modernization suggestions for a combined-cycle power plantINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2006Ahmet Cihan Abstract Energy and exergy analysis were carried out for a combined-cycle power plant by using the data taken from its units in operation to analyse a complex energy system more thoroughly and to identify the potential for improving efficiency of the system. In this context, energy and exergy fluxes at the inlet and the exit of the devices in one of the power plant main units as well as the energy and exergy losses were determined. The results show that combustion chambers, gas turbines and heat recovery steam generators (HRSG) are the main sources of irreversibilities representing more than 85% of the overall exergy losses. Some constructive and thermal suggestions for these devices have been made to improve the efficiency of the system. Copyright © 2005 John Wiley & Sons, Ltd. [source] Parametric analysis of a coal based combined cycle power plantINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2006T. Srinivas Abstract In the present paper thermodynamic analyses, i.e. both energy and exergy analyses have been conducted for a coal based combined cycle power plant, which consists of pressurized circulating fluidized bed (PCFB) partial gasification unit and an atmospheric circulating fluidized bed (ACFB) char combustion unit. Dual pressure steam cycle is considered for the bottoming cycle to reduce irreversibilities during heat transfer from gas to water/steam. The effect of operating variables such as pressure ratio, gas turbine inlet temperature on the performance of combined cycle power plant has been investigated. The pressure ratio and maximum temperature (gas turbine inlet temperature) are identified as the dominant parameters having impact on the combined cycle plant performance. The work output of the topping cycle is found to increase with pressure ratio, while for the bottoming cycle it decreases. However, for the same gas turbine inlet temperature the overall work output of the combined cycle plant increases up to a certain pressure ratio, and thereafter not much increase is observed. The entropy generation, the irreversibilities in each component of the combined cycle and the exergy destruction/losses are also estimated. Copyright © 2005 John Wiley & Sons, Ltd. [source] Design and performance analysis of impulse turbine for a wave energy power plantINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2005A. Thakker Abstract Wave energy is the most abundant source of renewable energy in the World. For the last two decades, engineers have been investigating and defining different methods for power extraction from wave motion. Two different turbines, namely Wells turbine and impulse turbine with guide vanes, are most commonly used around the world for wave energy power generation. The ultimate goal is to optimize the performance of the turbine under actual sea conditions. The total research effort has several strands; there is the manufacture and experimental testing of new turbines using the Wave Energy Research Team's (WERT) 0.6 m turbine test rig, the theoretical and computational analysis of the present impulse turbine using a commercial software package and finally the prediction of the performance of the turbine in a representative wave power device under real sea conditions using numerical simulation. Also, the WERT 0.6 m turbine test rig was upgraded with a data acquisition and control system to test the turbine in the laboratory under real sea conditions using the computer control system. As a result, it is proven experimentally and numerically that the turbine efficiency has been raised by 7% by reducing the hub-to-tip ratio from 0.7 to 0.6. Effect of tip clearance on performance of the turbine has been studied numerically and designed tip clearance ratio of 1% has been validated. From the numerical simulation studies, it is computed that the mean conversion efficiency is reduced around 5% and 4.58% due to compressible flow and damping effects inside OWC device. Copyright © 2005 John Wiley & Sons, Ltd. [source] Influence of the heat recovery steam generator design parameters on the thermoeconomic performances of combined cycle gas turbine power plantsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2004Manuel Valdés Abstract This paper proposes a methodology to identify the most relevant design parameters that impact on the thermal efficiency and the economic results of combined cycle gas turbine power plants. The analysis focuses on the heat recovery steam generator (HRSG) design and more specifically on those operating parameters that have a direct influence on the economic results of the power plant. These results are obtained both at full and part load conditions using a dedicated code capable of simulating a wide number of different plant configurations. Two different thermoeconomic models aimed to select the best design point are proposed and compared: the first one analyzes the generating cost of the energy while the second one analyzes the annual cash flow of the plant. Their objective is to determine whether an increase in the investment in order to improve the thermal efficiency is worth from an economic point of view. Both models and the different HRSG configurations analysed are compared in the results section. Some parametric analysis show how the design parameters might be varied in order to improve the power plant efficiency or the economic results. Copyright © 2004 John Wiley & Sons, Ltd. [source] The lignite electricity-generating sector in Greece: Current status and future prospectsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2004N. Koukouzas Abstract Lignite plays an important role in Greece's energy sector as it satisfies over 70% of country's needs in electric power. The extraction of lignite takes place mainly in three regions of Greece, namely Ptolemais-Amyndeon, Megalopolis and Florina. The annual production of lignite is around 60 million tons, out of which 48 million tons derive from the coal fields of northern Greece (Ptolemais-Amyndeon and Florina). Almost the entire lignite production is consumed for electricity generation, while small amounts of lignite are used for briquettes and other applications. The Greek coal-fired power plants, which are about 4500 MW, use conventional technology and they are old (an average of 30 years). In the coming years new coal fields will be exploited in Florina,another 2.5 million tons of coal,in order to satisfy the currently under construction 365 MW plant located at Meliti, Florina, Northern Greece. Even though the lignite reserves are widespread in Greece and other areas such as Elassona and Drama could possibly host power plants, it is expected that the Florina power plant will be the last coal-fired plant to be build in the country. Lignite has to compete with natural gas,the construction of the main gas pipeline network has been completed,imported oil and renewable energy sources. The new EU regulations on power plant emissions raise obstacles for the firing of lignite, although it is low in sulphur. It must be shown that lignite produces low cost electricity in a environmentally friendly manner. The utilization of fly ash and land reclamation can improve the situation in lignite mining. In particular, specific attention was paid to further research and potential use of fly ash in road construction, the production of bricks and concrete, and the production of zeolites from lignitic fly ash. The use of clean coal technologies in power plants can solve many emission problems. Specific measures to increase the efficiency of lignite-fired power units might include: identification of the loss sources of every unit, improvement of the cold end of the steam turbines, optimization of the beater wheel mills operation, and the combination of natural gas-fired turbines with the existing boilers. The liberalization of the electricity market needs to be considered seriously from the lignite industry, since the potential electricity producers can freely choose from all kinds of fuels, such as imported coal, oil, gas and renewables. However, Greek lignite meets the requirements for the security of supply, as indicated in the EU's Green Paper. It needs only to be competitive in the new energy sector by improving mining and combustion conditions. Further research on these topics, through the European Commission's ECSC and Framework Programmes, as well as the national programmes, is required. Copyright © 2004 John Wiley & Sons, Ltd. [source] Numerical and analytical calculations of the temperature and flow field in the upwind power plantINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2004Henry Pastohr Abstract The upwind power plant is an interesting system to generate electrical power from free solar energy. The authors have carried out an analysis to improve the description of the operation mode and efficiency. The pressure drop at the turbine and the mass flow rate have a decisive influence on the efficiency. This can be determined only by coupling of all parts of an upwind power plant. In this study the parts ground, collector, chimney and turbine are modelled together numerically. The basis for all sections is the numerical CFD programme FLUENT. This programme solves the basic equations of the thermal fluid dynamics. Model development and parameter studies particularly arise with this tool. Additional to the calculations using FLUENT a simple model is developed for comparison purposes and parameter studies. The numerical results with FLUENT compare well with the results given by the simple model, therefore, we can use the simple model for parameter studies. The basis for the geometry is the prototype Manzanares. Copyright © 2004 John Wiley & Sons, Ltd. [source] Recovery of CO2 with MEA and K2CO3 absorption in the IGCC systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2004Baoqun Wang Abstract Recovery of CO2 with monoethanolamine (MEA) and hot potassium carbonate (K2CO3) absorption processes in an integrated gasification combined cycle (IGCC) power plant was studied for the purpose of development of greenhouse gas control technology. Based on energy and exergy analysis of the two systems, improvement options were provided to further reduce energy penalty for the CO2 separation in the IGCC system. In the improvement options, the energy consumption for CO2 separation is reduced by about 32%. As a result, the thermal efficiency of IGCC system is increased by 2.15 percentage-point for the IGCC system with MEA absorption, and by 1.56 percentage-point for the IGCC system with K2CO3 absorption. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||