Kinetic study on recovery heat of granulated blast-furnace slag through biomass gasification using CO2 as gasification agent

The experiments of biomass char gasification in granulated blast-furnace (BF) slag using CO2 as gasification agent were carried out isothermally with a thermogravimetric analyzer between 1173 and 1323 K, systematically. The reaction rate increased first and then decreased with the increasing time in all conditions. The less complete reaction time, the higher maximum of reaction rate and the higher reaction reactivity were obtained with the increasing reaction temperature and content of granulated BF slag in the mixture. The D7 model (3D (Jander) model) calculated through the novel two-step method did not change with or without granulated BF slag, illustrating that the gas–solid diffusion was the main determining step during the reaction of biomass char gasification using CO2 as gasification agent. The obtained reaction rate constantly increased with the increasing temperature and content of granulated BF slag in the mixture. The activation energy obtained through the Arrhenius law lay in the range of 153.50–164.84 kJ mol−1 and it decreased with the increasing content of granulated BF slag in the mixture. Lastly, the kinetic equations of biomass char gasification in granulated BF slag using CO2 as gasification agent were constructed.