Thermodynamic and economic evaluation of reheat and regeneration alternatives in cogeneration systems of the Brazilian sugarcane and alcohol sector

Abstract

This work makes a technical and economic evaluation of incorporation of reheating and regeneration, as a way to increase efficiency of energetic systems and bagasse surplus, in cogeneration systems of Brazilian sugar and ethanol sector. Four scenarios were analyzed: Conventional (C0), with Reheat (C1), Regenerative (C2) and with Reheat and Regeneration (C3). Some of thermodynamic indicators used in evaluation were Surplus Bagasse Index and Exergetic Efficiency, for economic evaluation the Monte Carlo Method was used to give a Net Present Value (NPV) > 0 for each scenario. Technical evaluation indicates that Reheating (C1) increases bagasse surplus by 39.9% and exergetic efficiency by 1.90%, with respect to C0. Incorporation of 1–8 regenerators (C2) increases surplus bagasse and exergetic efficiency in the ranges of 103–160% and 5.03–8.07%, respectively. Reheat stage incorporation of 1–8 regenerators (C3) increases surplus bagasse in the range of 121–166% and increases exergetic efficiency in a range of 5.91–8.46%. Finally, it was estimated the potential of additional electric power generation during off-season and second generation ethanol production from surplus bagasse, with satisfactory results.