Predictive insights into CO2 capture carbonation conversion rates under different Ca-looping conditions in fluidized bed reactors

Carbonation cycles are vital for the efficiency, sustainability, and cost-effectiveness of the calcium looping process, making it a promising technology for carbon capture and storage. The research presented in this paper is based on experimental carbonation tests conducted on dual-interconnected fluidized bed reactors under realistic operational conditions in three different states including absence (NS, No Sulfur), 75 ppm (SP, Sulfur Poor), and 1500 ppm (SR, Sulfur Rich) SO2 concentration using high purity limestone as sorbent. Experimental results demonstrated that the carbonation conversion at the end of cycles 1, 2, and 10 was 28.6%, 17.5%, and 8.8% in the NS condition and 26%, 14.3%, and 6% in the SP condition, respectively. In contrast, the SR condition resulted in lower values of 22.24%, 7.32%, and 1.06% for the corresponding cycles, respectively. The results showed that higher SO2 concentration and reaction cycles reduce carbonation conversion. In this framework, Shrinking Core Model (SCM), Random Pore Model (RPM), and Fractal-like Random Pore Model (RPM-F) were applied in the present study, to model the carbonation reaction rate. Kinetic-model results demonstrated that RPM-F aligns more closely with experimental data in the first cycle than SCM and RPM, as indicated by the maximum absolute errors of 1.7%, 1.3%, and 0.9% in NS, SP, and SR conditions, respectively. By considering RPM-F as the best-fitting kinetic model, the carbonation conversion rates were predicted at 100 cycles in different conditions, yielding carbonation conversion degrees of 7.51%, 3.79%, and 0.19% at the end of the 100th cycle under NS, SP, and SR conditions.