CO2 Gasification Rate Analysis of Datong Coal Using Slag Granules as Heat Carrier for Heat Recovery from Blast Furnace Slag by Using a Chemical Reaction

The kinetics of Datong coal gasification in solid BF (blast furnace) slag using carbon dioxide as gasifying agent was studied between 1223 and 1423 K. The relative mass change during the gasification reaction was continuously monitored using a high-resolution thermogravimetric system. The influence of reaction temperature and coal/slag mass ratio in the reaction rate was analyzed. The reaction rate has a strong dependence on reaction temperature and coal/slag ratio. With increasing reaction temperature, carbon conversion, the peak value of reaction rate, the intrinsic surface reaction rate, and the reactivity index increases, and the time for complete carbon conversion decreased. The activation energy decreases with an increasing coal/slag ratio. When the coal/slag ratio is 1:0, the intrinsic the activation energy is 112 kJ/mol; however, when the coal/slag is 1:3, it is 53 kJ/mol. This indicates that BF slag is an active catalyst for carbon gasification. Reaction model A(m) (volume reaction model as proposed by Avrami-Erofeev) has the best fit on coal gasification using BF slag as heat carrier. The kinetic parameters applicable to the A(m) model different coal/slag ratios were obtained. The global rate equation that includes these parameters was developed.