Method of choosing optimal composition of biomass mixtures

Biomass has high content of volatile matter, hence devolatilization process is rapid. Necessity of supplying high fluxes of combustion air is usually one of the factor which leads to high values of air excess ratio and, as a consequence to decrease of energy efficiency. However it is possible to use mixture of different sorts of biomasses and thus obtain fuel which might equalize devolatilization rate. In this paper procedure for choosing optimal mixture of given sorts of biomasses based on their composition is presented. First, pyrolysis process of hemicellulose, cellulose and lignin was conducted using thermobalance. Based on the results and assuming that there are no interactions between pure components, optimal composition of the mixture were calculated. In the next step, according to obtained optimal composition, proportions of oak, pine, rape straw and wheat straw were calculated. Finally, pyrolysis of selected biomass mixtures was carried out. It was found that due to the presence of cellulose, which decomposes in very narrow temperature range, all of mixtures are characterized by the devolatilization with local maximum occurring at the temperature around 350°C.