Dimensionamento de um sistema de reaproveitamento de gases e vapor para pré-aquecimento da água de entrada da caldeira

Abstract

The present work presents a study for the design of a haust fumes/gases utilization system coming from viscera digesters in the flour and fat factory, as well as the study to return the condensate from the same process in order to preheat the Boiler feed water of a chicken slaughterhouse, located in Dourados, Mato Grosso do Sul. The study was initiated through collecting raw material quantity information from chicken slaughter production. The present work is composed by three main parts. In the first part, the useful energy, available energy and yield calculations for the Sermatec MZL 10.2 boiler were done based on thermodynamic law fundamentals. In the second part, the calculations of the flow rate of exhaust gases/fumes from each digester were done. The third part, and one of the most important, was the study about the heat exchanger and its designing to meet the system's needs was developed. As a basis for the designing, the fluid flow rates and the inlet and outlet temperatures of the fluids that performed the thermal exchange were determined or stipulated. In order to meet the energy efficiency aspect, new thermal balance calculations were done for the boilers, using water preheated by the new reuse of heat system studied. It was possible to establish an increase in the temperature of the water supply to the boiler from 25oC to 80oC. Therefore, it was possible to achieve a 8,2% increase in boiler efficiency, and a firewood consumption reduction of 5.950,5 m3 per year, which is about 16,6% reduction in fuel consumption. Other analysis would also be possible to be done in the industry, such as losses by thermal insulation, reuse of flash steam, among others.