Exergoeconomic Analysis of a Combined Cycle of Three Levels of Pressure

Author(s):  
Edgar Vicente Torres González ◽  
Raúl Lugo-Leyte ◽  
Martín Salazar-Pereyra ◽  
Miguel Toledo Velázquez ◽  
Helen Denise Lugo-Méndez ◽  
...  

This paper presents an exergoeconomic analysis of the combined cycle power plant Tuxpan II located in Mexico. The plant is composed of two identical modules conformed by two gas turbines generating the required work and releasing the hot exhaust gases in two heat recovery steam generators. These components generate steam at three different pressure levels, used to produce additional work in one steam turbine. The productive structure of the considered system is used to visualize the cost formation process as well as the productive interaction between their components. The exergoeconomic analysis is pursued by 1) carrying out a systematic approach, based on the Fuel-Product methodology, in each component of the system; and 2) generating a set of equations, which allows compute the exergetic and exergoeconomic costs of each flow. The thermal and exergetic efficiency of the two gas turbines delivering 278.4 MW are 35.16% and 41.90% respectively. The computed thermal efficiency of the steam cycle providing 80.96 MW is 43.79%. The combined cycle power plant generates 359.36 MW with a thermal and exergetic efficiency of 47.27% and 54.10% respectively.

Author(s):  
Ravin G. Naik ◽  
Chirayu M. Shah ◽  
Arvind S. Mohite

To produce the power with higher overall efficiency and reasonable cost is ultimate aim for the power industries in the power deficient scenario. Though combined cycle power plant is most efficient way to produce the power in today’s world, rapidly increasing fuel prices motivates to define a strategy for cost-effective optimization of this system. The heat recovery steam generator is one of the equipment which is custom made for combined cycle power plant. So, here the particular interest is to optimize the combined power cycle performance through optimum design of heat recovery steam generator. The case of combined cycle power plant re-powered from the existing Rankine cycle based power plant is considered to be simulated and optimized. Various possible configuration and arrangements for heat recovery steam generator has been examined to produce the steam for steam turbine. Arrangement of heat exchangers of heat recovery steam generator is optimized for bottoming cycle’s power through what-if analysis. Steady state model has been developed using heat and mass balance equations for various subsystems to simulate the performance of combined power cycles. To evaluate the performance of combined power cycles and its subsystems in the view of second law of thermodynamics, exergy analysis has been performed and exergetic efficiency has been determined. Exergy concepts provide the deep insight into the losses through subsystems and actual performance. If the sole objective of optimization of heat recovery steam generator is to increase the exergetic efficiency or minimizing the exergy losses then it leads to the very high cost of power which is not acceptable. The exergo-economic analysis has been carried to find the cost flow from each subsystem involved to the combined power cycles. Thus the second law of thermodynamics combined with economics represents a very powerful tool for the systematic study and optimization of combined power cycles. Optimization studies have been carried out to evaluate the values of decision parameters of heat recovery steam generator for optimum exergetic efficiency and product cost. Genetic algorithm has been utilized for multi-objective optimization of this complex and nonlinear system. Pareto fronts generated by this study represent the set of best solutions and thus providing a support to the decision-making.


Author(s):  
S. Can Gülen

Duct firing in the heat recovery steam generator (HRSG) of a gas turbine combined cycle power plant is a commonly used method to increase output on hot summer days when gas turbine airflow and power output lapse significantly. The aim is to generate maximum possible power output when it is most needed (and, thus, more profitable) at the expense of power plant heat rate. In this paper, using fundamental thermodynamic arguments and detailed heat and mass balance simulations, it will be shown that, under certain boundary conditions, duct firing in the HRSG can be a facilitator of efficiency improvement as well. When combined with highly-efficient aeroderivative gas turbines with high cycle pressure ratios and concomitantly low exhaust temperatures, duct firing can be utilized for small but efficient combined cycle power plant designs as well as more efficient hot-day power augmentation. This opens the door to efficient and agile fossil fuel-fired power generation opportunities to support variable renewable generation.


Author(s):  
Zygfryd Domachowski ◽  
Marek Dzida

Combined cycle power plants operate at thermal efficiency approaching 60 percent. In the same time their performance presents several problems that have to be addressed. E.g. gas turbines are very sensitive to backpressure exerted on them by the heat recovery steam generators as well as to ambient pressure and temperature.


Author(s):  
Akber Pasha ◽  
Andrew S. Ragland ◽  
Suichu Sun

The design, operation and usage of Heat Recovery Steam Generators (HRSG) has undergone considerable changes in the last 30 years. Nowadays, instead of as an option item, HRSGs are a major part of the Combined Cycle Power Plant. This makes it necessary to optimize the design and operation of the HRSG so that it can be integrated with the total plant. However, because of the complexity, it is not always feasible to evaluate all possible configurations for selecting the most optimum one within the given time constraints. An attempt is made here to present the parametric effect of various variables through descriptive graphs. These graphs are developed for general cases but can be applied to specific cases to give the trend rather than the absolute values. Cycle designers can use those to narrow down the cycle HRSG configurations. Plant operators may be able to use these to improve the performance by simple additions or modifications.


Author(s):  
J. E. Biles

Late in the summer of 1967 Southland Paper Mills, Inc. placed in operation a 52,000-kw combined cycle power plant. The plant utilizes two 13,550-kw gas turbines and one 25,000-kw single automatic extraction condensing steam turbine. The power plant furnishes the total power requirements for their new Sheldon mill. This paper presents background data on the mill and describes the power plant in some detail. Flow diagrams are presented and reviewed. Features of the generating equipment and the steam generators are described. Switchgear and load coordination is discussed. The operation and reliability of the plant to date are summarized and the combined cycle in terms of paper mill requirements is evaluated.


Author(s):  
Edgar Vicente Torres González ◽  
Raúl Lugo Leyte ◽  
Martín Salazar Pereyra ◽  
Helen Denise Lugo Méndez ◽  
Miguel Toledo Velázquez ◽  
...  

In this paper is carried out a comparison between a gas turbine power plant and a combined cycle power plant through exergetic and environmental indices in order to determine performance and sustainability aspects of a gas turbine and combined cycle plant. First of all, an exergetic analysis of the gas turbine and the combined is carried out then the exergetic and environmental indices are calculated for the gas turbine (case A) and the combined cycle (case B). The exergetic indices are exergetic efficiency, waste exergy ratio, exergy destruction factor, recoverable exergy ratio, environmental effect factor and exergetic sustainability. Besides, the environmental indices are global warming, smog formation and acid rain indices. In the case A, the two gas turbines generate 278.4 MW; whereas 415.19 MW of electricity power is generated by the combined cycle (case B). The results show that exergetic sustainability index for cases A and B are 0.02888 and 0.1058 respectively. The steam turbine cycle improves the overall efficiency, as well as, the reviewed exergetic indexes. Besides, the environmental indices of the gas turbines (case A) are lower than the combined cycle environmental indices (case B), since the combustion gases are only generated in the combustion chamber.


Energy ◽  
2014 ◽  
Vol 77 ◽  
pp. 553-561 ◽  
Author(s):  
Hassan Athari ◽  
Saeed Soltani ◽  
Seyed Mohammad Seyed Mahmoudi ◽  
Marc A. Rosen ◽  
Tatiana Morosuk

Author(s):  
Nikhil Dev ◽  
Gopal Krishan Goyal ◽  
Rajesh Attri ◽  
Naresh Kumar

In the present work, graph theory and matrix method is used to analyze some of the heat recovery possibilities with the newly available gas turbine engines. The schemes range from dual pressure heat recovery steam generation systems, to triple pressure systems with reheat in supercritical steam conditions. From the developed methodology, result comes out in the form of a number called as index. A real life operating Combined Cycle Power Plant (CCPP) is a very large and complex system. Efficiency of its components and sub-systems are closely intertwined and insuperable without taking the effect of others. For the development of methodology, CCPP is divided into six sub-systems in such a way that no sub-system is independent. Digraph for the interdependencies of sub-system is organized and converted into matrix form for easy computer processing. The results obtained with present methodology are in line with the results available in literature. The methodology is developed with a view that power plant managers can take early decision for selection, improvements and comparison, amongst the various options available, without having in-depth knowledge of thermodynamics analysis.


1991 ◽  
Vol 113 (4) ◽  
pp. 475-481 ◽  
Author(s):  
P. Lugand ◽  
C. Parietti

The new 200 MW class MS 9001F gas turbines allow combined cycle plants to reach even higher output levels and greater efficiency ratings. Size factor and higher firing temperatures, with a three-pressure level steam reheat cycle, offer plant efficiencies in excess of 53 percent. Heat recovery steam generators have been designed to accommodate catalytic reduction elements limiting flue gas NOx emissions to as low as 10 ppm VD (15 percent O2). A range of steam turbine models covers the different possible configurations. Various arrangements based on the 350 or 650 MW power generation modules can be optimally configured to the requirements of each site.


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