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[Display omitted] • Multi-stage circulation integrated SO 2 and CO 2 capture, coupled with NH 3 recovery. • Over 99.5% SO 2 and 70% CO 2 was captured with desorption duty of 2.48 GJ/t CO 2. • Adaptable strategies balanced efficiency and economy amid complex conditions. Amidst growing environmental concerns stemming from fossil fuel combustion, which releases a considerable amount of pollutants and greenhouse gas. In an effort to mitigate the costs of existing combustion flue gas desulfurization and CO 2 capture systems, a new multi-stage circulation (MSC) process for integrating capture of CO 2 and SO 2 using ammonia-based absorbents was proposed. Different functional zones were interconnected using ammonia (NH 3) and potassium carbonate (K 2 CO 3) blended solution as the absorbent, enabling efficient SO 2 capture in the 1st stage, CO 2 enrichment in the 2nd stage, CO 2 capture enhancement in the 3rd stage and recovery of escaped NH 3 in the 4th stage. Experimental results demonstrated the effectiveness of NH 3 /K 2 CO 3 solution in enhancing CO 2 capture efficiency. The overall CO 2 capture efficiency varied between 95.4 % and 84.1 % at inlet CO 2 concentrations ranging from 5 % to 30 %. Under typical combustion flue gas conditions of 622 ppm SO 2 and 15 vol% CO 2 , the process exhibited a SO 2 removal efficiency exceeding 99.5 %, with CO 2 capture efficiency surpassing 70 %. Furthermore, the CO 2 desorption duty was determined to be 2.48 GJ/t CO 2. 13C NMR results confirmed that simultaneous absorption of CO 2 and SO 2 led to the accumulation of SO 2 in the liquid phase, reducing the CO 2 loading in rich solvent. To address these challenges, coupled optimization strategies was proposed, ensuring high capture efficiency and low CO 2 desorption duty under the complex and variable conditions of flue gas parameters, SO 2 concentration, and CO 2 concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multi-stage circulation process enhanced CO 2 capture/regeneration performance. • The CO 2 loading of the rich MEA solvent was up to 0.514 mol CO 2 /mol amine. • The CO 2 regeneration duty reached 2.02 GJ/t CO 2 using NH 3 /K 2 CO 3 solution. One of the major barriers in industrial applications of solvent-based CO 2 capture is the significant energy consumption required for absorbent regeneration. In this study, a novel multi-stage circulation (MSC) CO 2 absorption process was proposed, which implemented independent regulation of each stage, resulting in enhanced CO 2 capture performance and reduction of CO 2 regeneration duty. The MSC absorber was designed with four stages from bottom to top, each serving distinct functions, including CO 2 enrichment, CO 2 main absorption, CO 2 capture efficiency enhancement and aerosol capture. Simulation of the MSC process achieved a rich ethanolamine (MEA) solvent CO 2 loading of 0.512–0.570 mol CO 2 /mol amine, which was 8.1 %–9.9 % higher than typical process. The effects of test duration, amine solution flow rates, reaction temperatures and inlet CO 2 concentrations on CO 2 absorption performance were studied using the MSC experimental platform. The CO 2 regeneration duty reduced by over 13.2 % of the MSC process compared to a typical process using 25 wt% MEA solution and by over 22.9 % using piperazine (PZ)/N-methyldiethanolamine (MDEA) solution. Furthermore, the utilization of NH 3 /K 2 CO 3 solution achieved an energy consumption reduction of over 41.7 %, resulting in a CO 2 regeneration duty as low as 2.02 GJ/t CO 2 (1.84 GJ/t CO 2 , subtracting the heat loss). Meanwhile, potential strategies for optimizing parameters of MSC process were proposed to address the complex and volatile conditions. [ABSTRACT FROM AUTHOR]