Gasification kinetics of chars from diverse residues under suitable conditions for the Sorption Enhanced Gasification process

Gasification kinetics for six chars from residual origin have been determined in a relatively low temperature range, low CO2 and high H2O partial pressures, typical from Sorption Enhanced Gasification (SEG) processes. In general, models based on the Random Pore Model (RPM) are the best fitting experimental results, but ash composition (in terms of alkali and alkaline earth metals) was crucial for the selection of the reaction model to be applied. Char conversion from biogenic waste with ash content higher than 30 % wt. was modelled with RPM model, but reaction rate for chars with the highest K/Si ratio was better described with modified versions of the RPM capable of predicting maximum reaction rates at high char conversion. For chars with similar ash content and composition, textural properties determined the pre-exponential factor and the activation energy for the gasification reaction (with both CO2 and H2O), while identical fitting parameters for the semi-empirical model were capable of predicting char conversion with time.

Automated summary

Gasification kinetics of six chars from residual origin were studied under relatively low temperature, low CO2, and high H2O partial pressures. The Random Pore Model (RPM) showed the best fit to experimental results, but the selection of the reaction model depended on the ash composition, specifically the presence of alkali and alkaline earth metals. Chars with ash content higher than 30% wt. were modeled with the RPM model, while chars with the highest K/Si ratio required modified versions of the RPM to accurately predict reaction rates. Textural properties played a key role in determining reaction parameters, such as the pre-exponential factor and activation energy, for chars with similar ash content and composition.