CO2 Gasification of Biomass Chars: A Kinetic Study

Khalil, Roger and Várhegyi, Gábor and Jäschke, Susanne and Gronli, Morten G. and Hustad, Johan (2009) CO2 Gasification of Biomass Chars: A Kinetic Study. ENERGY & FUELS, 23 (1). pp. 94-100. ISSN 0887-0624

Preview

Text 2008_Gasification_kinetics.PDF Download (1MB) | Preview

Abstract

The CO2 gasification of pine and birch charcoals was studied by thermogravimetric analysis (TGA) at CO2 partial pressures of 51 and 101 kPa. Linear and stepwise heating programs were employed to increase the information content of the experimental data sets. Low sample masses were used because of the high enthalpy change. Seven experiments with different experimental conditions were evaluated simultaneously for each sample. The method of least-squares was employed. Three reactions appeared in the temperature domain evaluated (600-1000 degrees C). The first and second reactions were due to the devolatilization and did not show a significant dependence upon the CO2 concentration. They were approximated by first-order kinetics. The third reaction corresponded to the gasification. Its modeling was based on an empirical approximation of the change of the reaction surface during the gasification and by a formal reaction order with respect to the CO2 concentration. Very close results were obtained for the two charcoals. The dependence upon the conversion could be well-approximated by power law kinetics. In the next step of the evaluation, the experiments of the two samples (14 experiments combined) were evaluated together, assuming common activation energy values and a common reaction order with respect to the CO2 concentration. This process led to nearly the same fit as the separate evaluation of the two samples. The activation energy of the gasification step was 262 kJ/mol. The reaction order of CO2 was 0.40.

Actions (login required)

Edit Item