Simulation of Limestone Calcination for Calcium Looping: Potential for Autothermal and Hydrogen-Producing Sorbent Regeneration

The combination of limestone calcination, catalytic methane reforming, and combustion in a membrane reactor is simulated as a possible means to achieve autothermal and hydrogen-producing sorbent regeneration for calcium-looping technology. Aspen simulation is employed in order to analyze the equilibrium performance of the process, while a simple one-dimensional, steady-state isothermal plug flow model is applied to provide a first estimate of the performance under fluidization conditions. The simulation results demonstrate that the performance of the process depends strongly on the operating temperature, CaCO3/gas molar feed ratio, and methane feed composition. Two separate correlations are proposed for estimating the optimal methane feed composition, resulting in autothermal and complete sorbent regeneration at 800 and 850 °C, respectively. The simulation results confirm the applicability of the proposed correlations and demonstrate the high potential of this novel technology for producing a highly concentrated hydrogen stream if robust high-temperature hydrogen-selective membranes can be installed inside the sorbent regenerator.