Influência das condições de operação da pirólise à vácuo da casca de arroz nas características do biocarvão

Abstract

The United Nations (UN) says that by 2050 the world population will reach 9.7 billion people, which will increase energy demand and the need to expand agricultural production. Therefore, it will be necessary to maintain a balance in agricultural production, in order that the sector can supply both the alternative fuels and the food industries. Rice is one of the main crops planted in Brazil and generates from 20 to 30% of its weight in rice husks. The rice husk is an agro-industrial residue with potential of applicability in the industry and an important source of heat production. Rice husk can be converted into an energy source by means of thermochemical decomposition techniques, with vacuum pyrolysis being one of these methods. When converted to an energy source through vacuum pyrolysis, it generates biochar, non-condensable gases and biooil. Biochar is a solid material with high carbon content, which can be used as fuel, input for producing chemicals, soil conditioning agent and other industrial applications. This research aimed to study the influence of vacuum pyrolysis operation parameters on the production of rice husk biochar (RHB). The parameters evaluated were: maximum operating temperature (400, 550 and 700 °C), heating rate (5 and 20 °C/min) and residence time of biomass into reactor (5 and 30 minutes). The average yield obtained from RHB was 60%, and the maximum operation temperature was the variable that most influenced the results. The average mass fractions of ash, fixed carbon and volatile matter present in the biochars were 51%, 22% and 19%, respectively. In general, the RHBs presented a close to neutrality (6.0-7.5) behavior and a conductivity ranging from 21 to 44 µS/com.