Design and analysis of a novel three-bed series VTSA process for enhancing adsorbent utilization under low-concentration CO2 exhaust gas conditions

The maritime transportation sector has seen a marked increase in carbon emissions over the past decade. This study presents a comprehensive carbon capture and storage system for ships fueled by liquefied natural gas. A novel series three-bed vacuum temperature swing adsorption (VTSA) process is proposed to capture low-concentration CO2 exhaust gases. This method can enhance the adsorbent utilization rate to achieve a higher CO2 recovery rate and reduce CO2 capture energy consumption by modifying the adsorption steps. A systematic analysis of the entire CO2 capture and storage system designed for LNG-fueled ships has been conducted. The results demonstrate that using a rapid vacuum step effectively increases product purity, with CO2 purity over 99.5 % in the proposed series three-bed process. Under the designed working conditions, the adsorbent utilization rate of the proposed series VTSA process is 93.92 %, 10.62 % higher than the conventional parallel VTSA process. In this context, the specific heat consumption of the series three-bed VTSA process is 5.05 MJ/kg CO2, which is 16.67 % lower than that of the conventional parallel process (6.06 MJ/kg CO2). The series process can capture more CO2 at a slightly lower cost (98.45 $/ton CO2) than the parallel process, achieving more carbon tax deductions.