Energy-exergy analysis and modernization suggestions for a combined-cycle power plant

SUMMARYCombined cycle power plants (CCPPs) have an important role in power generation. The objective of this paper is to evaluate irreversibility of each part of Neka CCPP using the exergy analysis. The results show that the combustion chamber, gas turbine, duct burner and heat recovery steam generator (HRSG) are the main sources of irreversibility representing more than 83% of the overall exergy losses. The results show that the greatest exergy loss in the gas turbine occurs in the combustion chamber due to its high irreversibility. As the second major exergy loss is in HRSG, the optimization of HRSG has an important role in reducing the exergy loss of total combined cycle. In this case, LP-SH has the worst heat transfer process.The first law efficiency and the exergy efficiency of CCPP are calculated. Thermal and exergy efficiencies of Neka CCPP are 47 and 45.5% without duct burner, respectively. The results show that if the duct burner is added to HRSG, these efficiencies are reduced to 46 and 44%. Nevertheless, the results show that the CCPP output power increases by 7.38% when the duct burner is used.

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“…The fuel composition is given in Table I. The reference ambient model [9] for air that is used in the current analysis is given in Table II.…”

Section: Calculation Methodsmentioning

confidence: 99%

Exergy analysis of a 420 MW combined cycle power plant

Ameri¹,

Ahmadi²,

Khanmohammadi³

2008

Int. J. Energy Res.

225

106

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“…Exegetic analysis enriches thermodynamic evaluation of energy conservation, because it provides the tool for a clear difference between energy losses to the environment and internal irreversibilities in the process [3]. In the recent, exergy analysis has imprtant role to reach to the better understanding of the process, to measure sources of inefficiency, to realize quality of energy (or heat) used [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Boiler Parametric Study of Thermal Power Plant to Opproach to Low Irreversibility

Arefdehgani¹,

Sadaghiyani

2015

AJEE

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Abstract:In this work, in order to reach to low irreversibilities, the energy and exergy have been analyzed in the boiler system of Tabriz power plant. First, it has been done to decrease the irreversibility of system. Second, flow and efficiencies of energy and exergy of the mentioned system have been studied. In the boiler, the energy efficiencies based on lower and higher heating value of fuel are 91.54% and 86.17% respectively. In other hand, the exergy efficiency is 43.98%. Comparing with Rosen and et al., it is demonstrated that, results have a logical agreement with experimental data. Accordingly, the EES used code, have been validated. Furthermore, the gas fired steam power plant efficiency has been increased by the use of irreversibilities reduction and diminution of excess combustion air and/ or the stack-gas temperature. Finally, these have been concluded, overall energy and exergy efficiencies of Tabriz power plant increase 0.497% and 0.46%, respectively when the fraction of excess combustion air decreases from 0.4 to 0.15.Also these efficiencies increase 2.196% nearly when, the stackgas temperature decreases from 159 to 97 °C.

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“…The source of exergy destruction (or irreversibility) in CC is mainly the combustion or chemical reaction and thermal losses in the flow path, respectively [7,22]. However, the exergy destruction in the heat exchanger of the system, i.e.…”

Section: Exergy Analysismentioning

confidence: 99%

Multi-objective optimization of a combined heat and power (CHP) system for heating purpose in a paper mill using evolutionary algorithm

Ahmadi

Almasi

Shahriyari

et al. 2010

Int. J. Energy Res.

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SUMMARYThe present study deals with a comprehensive thermodynamic modeling of a combined heat and power (CHP) system in a paper mill, which provides 50 MW of electric power and 100 ton h À1 saturated steam at 13 bars. This CHP plant is composed of air compressor, combustion chamber (CC), Air Preheater, Gas Turbine (GT) and a Heat Recovery Heat Exchanger. The design parameters of this cycle are compressor pressure ratio (r AC ), compressor isentropic efficiency (Z AC ), GT isentropic efficiency (Z GT ), CC inlet temperature (T 3 ), and turbine inlet temperature (T 4 ). In the multi-objective optimization three objective functions, including CHP exergy efficiency, total cost rate of the system products, and CO 2 emission of the whole plant, are considered. The exergoenvironmental objective function is minimized whereas power plant exergy efficiency is maximized using a Genetic algorithm. To have a good insight into this study, a sensitivity analysis of the results to the interest rate as well as fuel cost is performed. The results show that at the lower exergetic efficiency, in which the weight of exergoenvironmental objective is higher, the sensitivity of the optimal solutions to the fuel cost is much higher than the location of the Pareto Frontier with the lower weight of exergoenvironmental objective. In addition, with increasing exergy efficiency, the purchase cost of equipment in the plant is increased as the cost rate of the plant increases.

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Energy-exergy analysis and modernization suggestions for a combined-cycle power plant

Cited by 122 publications

References 18 publications

Exergy analysis of a 420 MW combined cycle power plant

Exergy analysis of a 420 MW combined cycle power plant

Boiler Parametric Study of Thermal Power Plant to Opproach to Low Irreversibility

Multi-objective optimization of a combined heat and power (CHP) system for heating purpose in a paper mill using evolutionary algorithm

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