Study of sugarcane bagasse/straw combustion and its atmospheric emissions using a pilot-burner

Abstract

This work conducted experimental combustion on a closed chamber using two different materials: mixture (1:1) sugarcane bagasse/straw and pre-treated biomass. The sampling method was an Andersen cascade impactor with eight stages. Tests were carried out on untreated biomass varying the velocities observed in the sampling duct (4.18; 5.20, 6.85, and 8.21 m.s^-1). Pre-treated biomass tests were performed at 4.19 m.s^-1 because in this condition there is a higher speed stability inside the duct. During the combustion tests, the concentration of emitted particles was higher for the lower speed range, with an order of 4.19 > 5.40 > 6.85 > 8.21 m.s^-1. The higher speeds observed inside the duct behaved as a dragging agent for particulate material. For the tests at the speed of 8.21 m.s^-1 where the flow inside the duct was 0.088 m³s^-1, this behavior is more evident. Considering the fine diameter particles (< 2.5 µm), they were emitted in a higher concentration, due to the biomass combustion process, which results in higher emission of ultrafine particles. The emission factors (EFs) obtained for PM₁₀ for untreated biomass were in the range of 0.414 and 0.840. On the other hand, considering the pre-treated biomass, these factors were 0.70 and 1.51. The EFs of PM from the burning of the pre-treated biomass were higher when compared to untreated biomass, which is mainly due to the higher temperature of the process due to the higher HHV (higher heating value) of this material, caused by the removal of hemicellulose (4.71 times) and a proportional increase in lignin (1.52 times). Biomass combustion has the potential to partially replace fossil fuels in heat and energy generation. Nevertheless, more stringent and comprehensive legislation should be established to ensure that air quality is maintained. Furthermore, the emission factors obtained in this study might be useful as input data for air quality modeling in the context of sugarcane's burning biomass, thus, contributing to the generation of inventories that include emissions of this nature.

Keywords: Biomass; Combustion; Emission factor; Particle material; Pilot-burner.