A New Approach for Evaluating Biochar Quality from Biomass Thermal Processing

This paper presents results from investigation on a new method for both evaluating char quality and control biomass thermal processing at range temperature between 250 and 375°C. Thermal processing of biomass in this temperature range is torrefaction and pyrolysis. Investigation was focused on processing Virginia Mallow energetic crops. Several strong correlations were observed as follows: carbon and hydrogen content in char, ash and volatile matter from char, calorific value and temperature of the process, and finally, acetic acid in condensate and carbon content in char. The correlation between acetic acid and carbon content was used to introduce a new method which can be considered as a diagnostic tool for determining char quality during biomass thermal processing. Hence, carbon content in char as well as its calorific value can be determined by measuring percentage of acetic acid in the condensate. This method provides relatively fast evaluation of the torrefaction/pyrolysis process, what makes it possible to continuously optimize process parameters (temperature, retention time) while the process is ongoing.