CO2 gasification characteristics and dynamic models of three coal chars

In order to study on CO2 gasification characteristics and dynamic of different coal chars, based on circulating fluidized bed (CFB) coal gasification technology, three rapid pyrolysis coal chars were prepared with Shenmu coal, Xinjing Zhundong coal and Kalimantan coal, at 900 ℃ in an electric horizontal tube furnace. The CO2 gasification of the coal chars were analyzed by non-isothermal and isothermal thermogravimetric measurements. In order to investigate the suitable dynamic model for CFB gasification technology, the nth-order distributed activation energy model (DAME) and random pore model (RPM) were applied to analyze the relationship between the CO2 gasification reaction rate and the carbon conversion rates of the coal chars. The results showe that the gasification reactivities of the coal chars are different for non-isothermal and isothermal gasification; the gasification reactivity is affected by coal types, gasification temperatures and alkali metals in coal ash; the reactivity of Kalimantan coal char is the highest while Shenmu coal char is the lowest, and the influence of temperature on gasification is obvious for Shenmu coal char; the experimental data of coal chars are fitted well by RPM for CFB gasification and there is a relationship between DAME and RPM. © 2015, China Coal Society. All right reserved.