Avaliação de um sistema de trigeração de energia a partir da biomassa como insumo energético primário

Abstract

This study presents an approach about the general operational characteristics of a simultaneous system of mechanical, electrical and thermal energy (heat and cold) production using biomass (renewable energy source) as the as the primary energetic input. This approach becomes particularly interesting as it emphasizes Cogeneration and, more specifically, Trigeneration, a relatively recent concept, that is clearly expanding in Brazil nowadays, specially in sugar-and-alcohol industries, due to the wide and growing use of sugarcane bagasse for vapour production in high pressure steam-boilers. Within the concept of Trigeneration, and based on real cases studies found on technical bibliography, the study explores the operational characteristics of a possible typical system configuration using burnt sugarcane bagasse, and enables evaluations related to energy usage and the estimation of efficiency along energy conversion successive stages (mechanical work performing, heat utilization in processes, electricity generation and cold production in ar conditioning absorption system, in order to provide chilled air for human thermal confort). Ultimately, the goal of this study is to investigate the viability of a hypothetical (but typical and technologically updated) system, contemplating: the characterization and evaluation of the operational conditions, the main operating points considering the trigeneration (including cold production by an absorption subsystem), the efficiency of processes involved and the correlations between the primary energetic consumption (sugarcane bagasse) in the face of the amounts of resultant energies. Based on this approach, the main results of this study reveal that, with the electrification of milling equipments (in place of steam driven equipments), it´s possible to increase the energetic performance of the plant and provide an increment of electrical energy generated amounts. The results also reveal that to aggregate systems in order to enable the Trigeneration will be an energetically effective procedure only if their energy demand is significant in front of the total available energy. In this work this fact was attested once that the operation of a 410 TR absorption chiller integrated to the system (in order to provide colled air to administrative and production support areas) increased the global utilization energy factor in only 1.7 percent in the most efficient configuration.