Studies of thermal behavior and emissions of biomasses in typical atmospheres of conventional combustion and oxy-fuel combustion

Abstract

This project is part of a research program in harnessing of bio-energy in the thermal area and aims at contributing to the use of biofuels in power generation technologies by assessing their environmental impact. In this sense, oxy-fuel combustion is a promising technology for the reduction of carbon dioxide (CO2) emissions and it is part of the set of CCS technologies (Carbon Capture and Storage). In such process, the fuel is burnt in an oxygen-rich atmosphere and the recirculation of the flue gases results in a effluent with a high CO2 concentration, ready to be sequestered. The application of this technique to the co-firing and neat biomass to produce energy is an attractive process under the environmental point of view. However, it is still a relatively new area and many technical aspects need to be clarified. Fundamental knowledge, such as thermal behavior and kinetics of biomass combustion and its blends with other fuels, is inherent to the development of efficient technological processes. The biomasses used in this study are agriculture wastes, specially bagasse and straw from sugar cane, pinus straw and peanut straw, presented as potential energetic sources. The project aims to perform basic laboratory studies of the combustion of these materials and their blends in typical atmospheres of oxy-fuel combustion (i.e., in CO2 + O2) and of conventional combustion in air (i.e., in N2+O2). Experiments will be conducted in a drop tube furnace (DTF) to evaluate CO, CO2. NOx and SO2 emissions and on a thermogravimetric balance applying Model Free kinetics to determine the kinetic parameters of combustion in the different atmospheres. In addition, the physical-chemical characterization of these materials, such as nitrogen and mercury porosimetry, elemental analysis, morphological analysis, calorific value and approximate analysis will be performed. This research will generate new knowledge in two important aspects: the assessment of pollutant emissions from the burning processes of biomasses and their blends in typical atmospheres of conventional and oxy-fuel combustion environments, and the association between physical-chemical characteristics of the biomasses and their thermal behavior including the study of combustion rates. (AU)