Kinetic modeling of gasification reactions of CO2and H2O for Thar lignite char at elevated pressures

Gasification reactions of Thar coal chars with CO(2)and H2O have been investigated, using pressurized thermo-gravimetric analyzer (PTGA). A quartz fixed-bed reactor was used to prepare coal char at 900 degrees C with a nitrogen environment. Dynamic heating segments were maintained with a constant heating rate during all experiments. The temperature was raised from room temperature to 1000 degrees C, at different pressures 1 atm., 5 atm., and 10 atm. using pure reacting gases (CO(2)and H2O). The weight loss data obtained from PTGA results were used to study the kinetic behavior of Thar lignite char for gasification reactions with CO(2)and H2O as gasifying reacting species. It was observed that gasification reactions of char with reacting gas CO(2)and char with reacting gas steam (H2O) initiated at 750 degrees C and completed after reaching 950 degrees C, at atmospheric pressure, but the occurrence of reactions was slightly delayed at high pressures. Volumetric Model and Grain Model were used to develop a kinetic model for Thar lignite. The direct plot and integral methods were used to calculate Arrhenius parameters such as the pre-exponential factor (A) and activation energy (E). An increase ofAandEwas also observed in increasing pressures. The activation energy (E) was investigated from 244.64 to 317.6 kJ/mol at atmospheric pressure; whereas, it is lying in the range of 286.13-356.67 kJ/mol at a pressure of 10 atm.