Experimental studies on gasification of the Shenmu coal char with CO₂ at elevated pressures

Abstract

The gasification rates of Shenmu coal chars with CO₂ were experimentally studied with a pressurized thermo- gravimetric analyzer (PTGA). Shenmu coal is a typical Chinese coal, and the coal char was prepared by a fixed-bed reactor in nitrogen at 900 °C. The experiments were carried out in the dynamic heating segments from 750 °C to 1,000 °C, and the reaction pressure increased from 0.1MPa to 3.1MPa with pure CO₂. The external diffusion resistances were minimized by increasing the flow rates and decreasing the thickness of sample layer before the test, to ensure the reactions were under kinetic control. The results show that the gasification rates increase proportionally to the 0.1 power of the CO₂ partial pressure. The unreacted-core shrinking model was applied to predict the reaction rate by changing the molar fraction of CO₂ at 0.6Mpa and 1.6Mpa total pressures, which showed a good match with experimental data.