Comparative analysis of absorption, membrane, and hybrid technologies for CO2 recovery

Abstract

The implementation of hybrid systems for carbon dioxide (CO2) capture has been studied by several researchers in recent years. Systems based on the combination of membrane and absorption with amines technologies are the ones that have attracted more interest as industrial applications. In this work, a parametric sensitivity analysis was performed on the hybrid system (membrane and absorption with amines), and on each technology separately, in order to evaluate the most relevant operating variables of each system. Then, the energy requirements and greenhouse gases emissions (GHG) were estimated using process simulation tools. A natural gas stream with a concentration higher than 20 mol% of CO2 was used as feed. This stream was considered the feed of the three different treatment systems: two membrane systems, an absorption system with amines, and a hybrid system (membranes and amines). In the case of the membrane systems, a single-stage and two-stage arrangements were considered, using the total area of membrane as the response variable under analysis. The results showed that the single membrane area module requires around 2700 m2, while the two-module system allowed a 28% reduction in the total area. Amine inlet flows on the separation performance in the amine system were studied, determining a minimum value of 322.54 m3/h of diethanolamine (DEA) at 30% w/w. The hybrid process required a membrane area of 400 m2 and an amine flow of 123.25 m3/h to meet gas sale specifications. Considering energy requirements and carbon emissions, the hybrid system showed the best results among the analyzed technologies. The specifications were reached by showing low energy costs and carbon emissions and an acid gas stream with appropriate purity for enhanced oil recovery (EOR) and other applications.