(622b) Impact of Design and Operational Parameters on the Performance of a Rotary Adsorber for Carbon Capture

The AR6 report issued by the Intergovernmental Panel on Climate Change (IPCC) has indicated that limiting overshoot of 1.5 °C requires Carbon Dioxide Removal (CDR) technologies for hard-to-abate emissions [1]. Similarly, in the transition to low-carbon energy sources, renewables as well as fossil-based fuels with carbon capture and storage (CCS) will be needed [1]. Therefore, the development of efficient separation processes for carbon dioxide (CO₂) removal at concentrations ranging from 0.04 mol% (CDR) to 25 mol% (CCS) is essential for future emissions reductions. Adsorption-based processes present a promising option, allowing mild regeneration conditions together with reduced sorbent make-up requirements. Today, studies exploring unique contactor designs for the development of adsorption-based carbon capture remain limited, despite their importance for the advancement of the technology.

Moving beds, and specifically rotary adsorbers, represent a candidate contactor design for carbon capture, albeit one that has been scarcely investigated. Rotary adsorption has been considered through equilibrium modelling for post combustion carbon capture [2]. However, a kinetic model is required to understand the impact of all design/operational parameters and test the full range of carbon capture scenarios. A rotary adsorber is a continuously rotating adsorption bed with a high diameter-to-depth ratio, which achieves sorbent regeneration through either temperature swing (TS) or concentration swing (TCS) desorption. The rotary adsorber offers the benefit of process intensification since all cycle steps are performed within one vessel, as well as the ease of cycle control by adjusting the wheel speed. The geometry of the unit leads to low pressure drop, thereby reducing energy requirements and enabling high volumetric flows in CDR applications.

In this work, we have investigated the use of a rotary adsorber and assessed its performance for various carbon capture scenarios (0.04 mol% - 25 mol%). To do this, we have created a one-dimensional dynamic adsorption model that describes the spatial and temporal evolution of gas and adsorbed phase concentration profiles in the unit. We have applied this model considering both monolithic and beaded sorbent packing, as well as different TS/TCS configurations. Our model highlights the impact of design (i.e. sorbent properties, aspect ratio, and sectioning) and operational parameters (i.e. wheel speed, feed condition and composition) on the key process performance indicators such as productivity, purity, and recovery. In our presentation, we will describe the effects of these parameters along with a sensitivity analysis on the operation of the rotary unit and a comparison with a fixed bed design.

Overall, our study provides underlying knowledge on the operation of a rotary adsorber. It also highlights the strengths and weaknesses of such configuration in the context of carbon capture and indicates directions for optimization.

[1] IPCC. AR6 Report (2023).

[2] L. Herraiz at al., Front. Energy Res. 8 (2020) 482708