Enhanced SO2 and CO2 synergistic capture with reduced NH3 emissions using multi-stage solvent circulation process

NH3-based SO2 and CO2 synergistic capture technology shows promise in reducing the costs associated with current flue gas desulfurization and CO2 capture systems. However, it faces challenges such as NH3 slip and high energy consumption. In this study, we proposed an advanced Multi-Stage Solvent Circulation (MSC) process that incorporates a desulfurization-washing solution circulation, which involved partitioned absorption according to different functions of SO2 capture, CO2 capture, and NH3 emission control. The experimental results demonstrated that using desulfurization solution in place of water for washing reduced the NH3 emissions from the absorber and desorber by 10.6 % and 7.9 %, respectively. Additionally, the recovered NH3 enhanced SO2 capture, resulting in a 61.8 % decrease in SO2 emission concentration. A pilot-plant trial model for SO2 and CO2 synergistic capture was further developed using Aspen Plus. The impact of operational time and parameters on capture efficiency and energy consumption were analyzed. Under typical flue gas conditions, the process achieved SO2 capture efficiency of > 99 %, regeneration energy consumption of 2.42 GJ/t CO2, NH3 emissions of < 5 ppm. This study presents a novel approach for designing a SO2 and CO2 synergistic capture system, which has the potential to facilitate the economic and effective implementation of post-combustion flue gas pollutant control management and carbon emission reduction.