A new approach to exergy analysis is proposed for examing the consumption of energy as the minimum driving force and of exergy consumption that is avoidable, and for the development of a method to predict the alternatives in system improvement by exploring possible reduction in the avoidable exergy consumption. Also suggested in this study is a dimensionless parameter gamma (AVO), which is the ratio of avoidable exergy consumption over total fuel energy input to the system. Detailed analyses, including the calculation of exergy consumption, exergy loss and avoidable exergy consumption, were conducted for each component in the syngas cooling system in the Integrated coal Gasification Combined Cycle (IGCC) plant, to prove the effective application of the proposed method. The analysis showed that the rank of avoidable exergy consumption was different from that of total energy consumption, and hence it confirmed that an energy analysis by conventional methods misled the focus of improvement in system design. The methodology developed in this study offers a new approach for system designers to analyze and to improve the performance of a complex energy system such as an IGCC plant.
ABB Lummus, "Heat Transfer Corp," APEX manual. Hague, Netherland, 1993
Bechtel, "Power Corporation. IGCC Process Evaluation for KEPRI," Gaithersberg, USA, 1995
De Ruyck J, Bram S, Energy Conv. Manag., 38, 15, 1997
Feng X, Zhu X, Zheng J, "Practical Exergy Method for System Analysis," 31th IECEC, 2068, 1996
Johnson MS, "The Effects of Gas Turbine Characteristics on Integrated Gasification Combined-cycle Power Plant Performance," Ph.D. Dissertation, Stanford University. California, 1989
Kim JJ, Park MH, Ahn DH, Kim NH, Song KS, Kim CY, Energy Eng. J., 5(1), 8, 1996
Kim JJ, Park MH, Kim HS, Kim CY, Theor. Appl. Chem. Eng., 2(1), 581, 1996
Kim JJ, Park MH, Song KS, Cho SK, Seo SB, Kim CY, Energy Eng. J., 6(1), 104, 1997
Lobachyov K, Richter HJ, ASMEAES, 35, 231, 1995
Lozza G, Chiesa P, Devita D, J. Eng. Gas Turbines Power, 118, 737, 1996
Rosen MA, "The Development and Application of a Process Analysis Methodology and Code Based on Energy, Cost, Energy and Mass," Ph.D. Thesis, University of Toronto, 37, 1986
Rosen MA, ASME AES, 1, 71, 1985
Stone KR, "ASPEN Simulation of Fludized-bed Entrained-flow Integrated Gasification Combined-Cycle Power Plants, Technical Notes," U.S. Department of energy, Morgantown Energy Technology Center, Mogantown West Virginia, METC, 85, 4027, 1985
Szargut J, Morris DR, Steward FR, "Energy Analysis of Thermal, Chemical, and Metallurgical Process," Hemisphere, 41, 1988