A SUGAR MILL COGENERATION PLANT REPOWERING ALTERNATIVES EVALUATION THROUGH THE COMBINATION OF THERMODYNAMIC AND ECONOMIC CONCEPTS

By Electo Eduardo Silva Lora, Marcelo Zampieri, Osvaldo José Venturini, Jose Joaquim Santos

(Excellence Group in Thermal Power and Distributed Generation, Federal University of Itajubá).

electo@unifei.edu.br

ABSTRACT


This paper shows the advantages of using thermodynamic and economic concepts, the so called “thermo-economics”, to carry out the assessment of repowering alternatives in sugar and alcohol mills’ cogeneration plants, which allows the determination of the cost of each product separately. The present scheme of an existing sugar and alcohol mill (1000 tonnes of crushed cane per hour) and four repowering alternatives are modelled using the Gate-Cycle Enter software. Different steam parameters (63 bars/480oC and 82 bars/520oC) are considered. The cogeneration plant thermal efficiency is calculated according to four different criteria and conclusions are made according to the way each of these criteria considers real processes. Exergetic and monetary cost for steam, mechanical power and electricity are presented for all the evaluated scenarios.

KEYWORDS: cogeneration, sugar and alcohol industry, thermoeconomics.

(ISSCT XXVIth CONGRESS Durban, South Africa 29th July - 2nd August 2007)
http://issct.intnet.mu/ComCop2007.htm