Numerical Simulation on the Sodium-Based Dry Desulfurization Process in Low SO2 Concentration Flue Gas

The sodium-based dry desulfurization process is a promising technology for flue gas desulfurization. However, its industrial application still heavily relies on empirical experience. In this study, a three-dimensional numerical model was established for an industrial sodium-based dry desulfurization process. Numerical simulations were conducted to investigate the effects of the desulfurizer particle mass flux, particle size, and internal structures of the reactor on desulfurization efficiency. The results show that SO2 is mainly removed through the reaction path in which the desulfurizer of NaHCO3 (sodium bicarbonate) thermally decomposes to Na2CO3 and then reacts with SO2. Increasing the mass flux of the desulfurizer and decreasing the particle size can significantly improve the desulfurization efficiency. However, the excessive addition of the desulfurizer of NaHCO3 leads to waste and, thus, increases the desulfurization cost. Among the internal structures, the swirl-type structure achieves the maximum improvement in desulfurization efficiency but also results in a significant increase in pressure drop. In contrast, the diffuser-type structure has a low pressure drop while providing an acceptable enhancement in desulfurization efficiency. The research results provide effective references for the design and optimization of the sodium-based dry desulfurization process for flue gas treatment.