Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
THERMOECONOMIC ANALYSIS OF A SUGARCANE PLANT COGENERATION SYSTEM UNDER DIFFERENT THERMAL INTEGRATION LEVELS
Submission Author:
Hiago Braz , ES
Co-Authors:
Hiago Braz, Igor Belisario, Izabela Barbosa, Carlos Eduardo Silva Abreu, Carlos Filipe Lacerda Martins, Felipe Malheiros
Presenter: Hiago Braz
doi://10.26678/ABCM.COBEM2021.COB2021-1317
Abstract
The cogeneration system is in fact the most important sector in sugarcane mills, providing energy for sugar, alcohol and electricity production, the latter being responsible for self-sustainable generation and selling the surplus to the grid. Improving overall efficiency has always been a common goal in mills, however, nowadays there is a major concern in process development, after all, technology has provided equipment with higher efficiencies and more complete researches, uncovering many resources for cycle improvements. Thermal integration is a great technique for energy exploitation, since it performs a thermal exchange between the process streams and reduces successive losses from it, which directly reflects on the cogeneration system and consequently in final products of the plant. Hence, there are several ways to evaluate such systems, in terms of energy, exergy, financial, and others. Thermoeconomics is based on exergy and economy concepts, where the formation process of exergetic and monetary costs is analyzed, relating them to the plant fuels. These processes can be visualized by the means of a productive diagram that considers productive purpose of each component of the plant defining its fuel and product graphically. The productive flows are defined trough the physical flows presented in the flow sheet of the system and the components are connected by ficticious equipment (junctions and bifurcations). In addition, some methodologies use total exergy (E model) to define the productive structure of the system while another dissociate exergy in enthalpic and entropic components (H&S model). This paper aims to execute a thermoeconomic evaluation in a cogeneration system of a sugarcane plant by considering different thermal integration levels in process. The analysis will be performed using the E and H&S thermoeconomic models applying productive diagram, in order to identify and quantify the impact of integration on the system final products costs, process steam and electricity. The exergetic or monetary results are represented on a straight line with ordinated pairs of the heat and power unit cost, which means that changing the process steam consumption, due to integration, generates straight lines with different inclinations, once this line is associated with the ratio of the final products and the overall exergetic efficiency. The application of thermal integration, no matter its level, provides an increase in process efficiency, which confirms the improvement potential and reiterates the importance of exploring new methods for the rational steam utilization.
Keywords
thermoeconomic, exergy, thermal integration, sugarcane plant
