Sistema de resfriamento de fermentação em usina sucroenergética utilizando chiller de absorção acionado por biogás de vinhaça

Abstract

The Brazilian sugarcane mill has traditionally used cooling towers in the fermentation process cooling. However the minimum temperature achieved by a cooling tower is limited by the wet bulb temperature, which in Brazil is relatively high. This makes the cooling towers systems, although more economical, inefficient at fermentation cooling. Thus, this work aimed to propose a system for cooling the must during fermentation process in a sugarcane mill. The proposed system consists of double effect lithium bromide absorption chillers. The chillers are direct-fired type and utilize natural gas or diesel, therefore the replacement of traditional fuels with biogas obtained from the biodigestion of vinasse was proposed. Mathematical modeling of the absorption chiller was performed. The method of logarithmic mean temperature differences was used to analyze the heat exchanger of fermentation and the evaporator of the cooling system in order to find the best operating point. From the data of vinasse production of the sugarcane plant the potential of biogas production was evaluated. The results shows that de plant has a potential of biogas production higher than cooling system utilization.