Estudo do potencial bioenergético do resíduo de cervejaria considerando suas propriedades físico-químicas, parâmetros bioenergéticos e comportamentos da combustão

Abstract

The use of biomass as a renewable energy source is a viable alternative to replacing fossil fuels, being able to reduce environmental impacts, and meeting the country's strong energy demand. This work aimed to investigate the bioenergy potential of Brewery Waste (RC) through the study of its physicochemical properties, bioenergy parameters, and the combustion of this biomass by thermogravimetry. The physicochemical properties presented results of apparent density of 436.3 kg m-3 and proximate analysis with contents of volatile matter of 80.5%, fixed carbon of 16.5%, ash of 3.0%, and moisture of 2.4%. For the ultimate analysis (theoretical and experimental), maximum levels of C of 48.0%, H of 6.8%, O of 42.9%, N of 4.2%, and S of 0.7% were found. The chemical analysis resulted in contents of cellulose of 37.6%, hemicellulose of 29.4%, lignin of 13.5%, and extractives of 19.5%. The MEV analysis was used to assess the structural properties of biomass and ensure the particle diameter needed for the combustion process. The higher and lower calorific values were calculated by different empirical equations depending on the proximate and ultimate analyses, with values between 17.5 and 21.0 MJ kg-1 and 17.3 and 18.3 MJ kg-1, respectively. Thus, RC has satisfactory characteristics compared with fossil fuels for application in thermal processes such as combustion. Bioenergy properties included bioenergy density (7.78 GJ m-3), fuel value index (2.59 GJ m-3), fossil fuel equivalence (Veq), and CO2 retention potential (PRCO2). The results of Veq and PRCO2 were compared to those of fossil fuels (petroleum, diesel oil, fuel oil, and gasoline), showing higher equivalence values with gasoline, i.e., 238.58 L (Veq) and 940.00 L (PRCO2). Therefore, there is a satisfactory reduction in CO2 emissions by RC biomass compared with fossil fuels and reference biomasses (which presented lower values for the mentioned parameters). Finally, the study of the thermal decomposition of RC was carried out through thermogravimetry experiments in an oxidizing atmosphere for heating rates of 10, 15, and 25°C min-1. From the thermogravimetry (TG) and derivative thermogravimetry (DTG) results, the steps of RC degradation in the combustion process were determined, classified as moisture (25 - 150°C), oxidative pyrolysis (150 - 390°C), and combustion (390 - 650°C), in addition to the characteristic process temperatures: ignition (247.8 - 261.6°C), peak (281.2 - 296.3°C) and burnout (639.6 - 713, 6°C). The RC biomass appeared as a promising renewable source to produce bioenergy, being highly attractive according to the physicochemical properties, bioenergy and combustion behavior obtained. The RC revealed a favorable and satisfactory burning performance, providing helpful information for large-scale application, like an example, in the planning and control of power plants from biomass, contributing as a sustainable and renewable source of energy.