CO2 gasification of coal under concentrated thermal radiation: A numerical study

Solar coal gasification is a promising technology to convert coal into gaseous fuel. In this study, a steady-state one-dimensional (1D) two-phase model was developed to simulate CO2 gasification of coal in a quartz fluidized bed reactor directly exposed to concentrated thermal radiation as the heating source. Coupled with chemical kinetics, the present model encompasses energy equations for the gas phase, the solid phase, and the quartz reactor. The discretized energy equations were solved using the Levenberg-Marquardt algorithm. The initial carbon particle size was 140 μm and the peak radiative heating flux was as high as 1270 kW m− 2. The CO2 flow velocity for fluidization was in the range of 0.10 to 4.0 m min- 1 under standard conditions (25 °C, 1 bar). Simulated gas and coal particle temperature distributions, CO production rates, product gas compositions, and coal conversion rates were in good agreement with the experimental data reported in the literature. Furthermore, the present simulation provided insightful explanation on the optimum fluidization velocity for maximum CO production rate or maximum solar to chemical energy conversion. The present simulation also provided an energy balance analysis of the solar CO2 gasification process, which is challenging to conduct in experimental studies.