Co-gasification kinetics of coal char and algae char under CO2 atmosphere

Abstract

ABSTRACTIn this study, Newlands coal char and spirulina algae char were prepared separately in a fixed bed reactor with a pyrolysis temperature of 1000 ºC. The isothermal CO2 co-gasification experiment was done using a thermogravimetric analyzer in the temperature range of 800–1000 ºC. The volumetric model (VM), the shrinking core model (SCM), the random pore model (RPM) and the modified random pore model (MRPM) were applied to describe the gasification kinetics of the samples. The results show that synergetic effects were observed for all ratios while the 5:5 blend demonstrates the best performance which may be attributed to the high content of potassium included in the algae char which in turn promotes the catalytic effect. Among the above-mentioned models, RPM was found to be predicting the conversion profile best among all tested models except for the algae sample which failed to fit the data by RPM and hence MRPM was applied for the algae sample only. RPM and MRPM were adopted to calculate the kinetics parameters. The activation energy and the pre-exponential factor were determined using the Arrhenius equation. The activation energy for all chars was found to be in the range of 100–200 kJ/mol.