Melhoria na eficiência térmica de uma caldeira aquatubular alimentada a cavaco florestal

Abstract

In this work, operational data of a water-tube boiler, located at the city of Ponta Grossa-PR, with production capacity of 50 t/h of saturated steam and fed by wood chip, was used to analyze its thermal yields through direct and indirect methods. In the indirect method, the calculations were realized based on the energy supplied by the fuel and the losses related to the process. The results from the initial diagnosis identified the presence of combustion’s air excess of just 19%, recognizing the air deficiency for the employed fuel and also a big yield loss due to the high tax of humidity in the fuel. After the necessary improvements as the rise of the available air supply for the furnace burn and ensuring the supplies of a biomass with lower tax of humidity, there was a gain in thermal efficiency from 82.85% to 85.33% since the excess air setting to about 60%. Thus, the operational modifications ensured a better oxidation of the fuel, leading to the best use of the energy supplied to the steam generator and a reduction of costs due to the decrease of up to 20% in fuel consumption.