ASABE Technical Library - Abstract

Abstract. The objective of this study was to characterize rice hull and wood chips biochar produced in a top-lit updraft gasifier. This gasifier has been proven to convert biomass to biochar, but little is known about the properties of this product. Depending on its properties, biochar can be used for a number of applications such as soil conditioning, heat generation and adsorption of pollutants. As part of this project, biochar was produced at four airflows, 8, 12, 16 and 20 lpm. Two insulation conditions were studied, no-insulation and insulating the reactor with 88.9 mm of Fiberglass®. Elemental composition, high heating value, BET surface area analyses and proximate analysis of the biochar were carried out. It was found that the airflow and insulation significantly influenced the chemical composition of the biochar. In addition, it was found that the physical properties of the initial biomass played an important role in the final composition of biochar. For instance, the carbon content of biochar from rice hulls decreased from 40.9 to 27.2% as the airflow increased from 8 to 20 lpm when the reactor was insulated. In contrast, the carbon content of biochar from wood chips increased from 82% to 86% at the same conditions. Despite these variation in the carbon content, the BET surface area of biochar from rice hulls increased from 9.4 to 183 m²/g as increasing the airflow rate with insulation. Similarly, the BET surface of biochar from wood chips increased from 56 to 405 m²/g at the same conditions.