Influence of steam in carbonation stage on CO2 capture by Ca-based industrial waste during calcium looping cycles

This work investigated the effect of steam concentration in carbonation on CO2 capture by carbide slag during the calcination/carbonation cycles in a dual-fixed bed reactor. Under severe calcination conditions, the pore structure of calcined carbide slag carbonated in the presence of 20 vol. % steam is better than that in the presence of 60 vol. % steam. In the presence of steam in carbonation, the drop of carbide slag in carbonation conversion under severe calcination conditions (950 °C, pure CO2) is relatively smaller than that without steam. Higher steam concentration results in significantly higher carbonation conversion of carbide slag for short carbonation duration (e.g., 5 min), because higher steam concentration leads to greater accelerating effect on CO2 diffusion through product layer. Steam exhibits a two-side effect on the carbonation performance of carbide slag, and the effect of high steam concentration on carbonation conversion is higher than that on pore structure.