Title: Improving steam power plant efficiency through exergy analysis: effects of altering excess combustion air and stack-gas temperature

Authors: Marc A. Rosen, Raymond Tang

Addresses: Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario, L1H 7L7, Canada. ' Kishimoto Sangyo (HK) Co., Ltd., Unit 2608, The Metropolis Tower, 10 Metropolis Drive, Hunghom, Kowloon, Hong Kong

Abstract: Modifications are examined to increase coal-fired steam power plant efficiency by reducing irreversibilities in the steam generator, including decreasing the fraction of excess combustion air, and/or the stack-gas temperature. Overall-plant energy and exergy efficiencies both increase by 1.4% when the fraction of excess combustion air decreases from 0.4 to 0.15, and by 3.5% when the stack-gas temperature decreases from 149°C to 87°C. When both decreases occur, plant energy and exergy efficiencies both increase by 4.1%. If theoretical combustion air is used, the plant energy and exergy efficiencies both increase by 4.7% when the stack-gas temperature is 87°C.

Keywords: exergy analysis; coal; steam power plants; combustion air; steam generator; stack gas; energy efficiency; exergy efficiency; coal-fired power plants; irreversibilities.

DOI: 10.1504/IJEX.2008.016011

International Journal of Exergy, 2008 Vol.5 No.1, pp.31 - 51

Published online: 02 Dec 2007 *

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