Análises energética e exergética e modelo de simulação de um alto- forno de calcinação a gasogênio de biomassa de eucalipto

Abstract

In calcination industries, there is a strong reliance on the use of fossil fuels to meet the energy demand of the limekilns, both on a global and national scale. However, due to restrictions on the use of fossil fuels arising from concerns such as the depletion of reserves, increased greenhouse gas emission regulations, and rising fuel costs, the quicklime industry has been exploring alternative fuels to fulfill the energy requirements of the calcination process. So, the main purpose of this study was to conduct energy and exergy assessments of the performance of a vertical limekiln in Brazil. This limekiln utilizes producer gas as a renewable biofuel, generated through the gasification of eucalyptus wood in an integrated system. The assessments were performed considering the main equipment involved in the process. Industrial data was collected, and mass, energy, and exergy balances were developed using thermodynamic principles. Supplementary information from the literature was used to complement the equipment characterization. The obtained novel results were compared and discussed with similar limekilns using fossil fuels and biomass gasifiers reported by the literature. The overall results for energy efficiency, exergy efficiency, exergetic sustainability index, depletion number, and environmental destruction index were 42.0%, 23.6%, 1.3, 0.8, and 4.2, respectively, for the calcination process. These results are consistent with those found in the literature used for reference. Based on these results, it was possible to investigate the sustainability of the calcination process operating with a renewable biofuel and identify opportunities for exergy recovery, such as the reutilization of heat from the limekiln's exhaust gases, valorization of exergy from the waste generated in the eucalyptus wood gasifier, and the reuse of lost heat from the limekiln and gasifier. These opportunities have the potential to promote biofuel savings, reduce quicklime production costs, and decrease the emission of pollutants during the calcination process. The conducted assessments can serve as a foundation and undergird researchers to explore the implementation of renewable biofuels, such as producer gas derived from eucalyptus wood, as an alternative to conventional fossil fuels used in limekilns.