(371ac) Optimal Scale Analysis of Rotating Packed Bed (RPB) for Modular CO2 Capture

This study focuses on optimizing the Rotating Packed Bed (RPB)-based CO₂ capture process, aiming to identify the practical and economically optimal scale for modularization suitable for commercial application. Despite the potential of RPB technology to significantly improve energy efficiency and spatial feasibility for CO₂ capture, the challenges of scaling up and refining the design of the RPB unit have remained a substantial hurdle. In particular, the mechanical limitations or rise in maintenance expenses stemming from packing rotation imply that RPB units cannot be unequivocally deemed advantageous for large-scale processes. This study explores the economically viable scale for deploying RPB-based CO₂ capture systems, addressing both the technological and economic aspects within the practical limits of unit design. A rigorous process model for RPB columns employing Monoethanolamine (MEA) in the commercial software gPROMS is used for the optimization and cost evaluations. The optimization-based determination on RPB unit design and operating conditions strikes a balance between enhancing throughput capacity by enlarging unit design or increasing rotational speeds, and incremental capital and operational costs.

Our results indicate the potential for CO₂ capture at optimal scales of 15, 100, and 200 tons per day (TPD) from off-gas streams with CO₂ concentrations of 4.0%, 14.5%, and 24.8%, respectively, utilizing 50wt% MEA solvent and RPB absorber units with a 1 m outer radius. Our findings emphasize the significant potential for reducing CO₂ avoidance costs in small to medium-scale CO₂ capture, primarily through capital cost, operation and maintenance (O&M) cost savings in an absorber, and the energy efficiencies gained from high-concentration amine solvents. Acknowledging the constraints of current RPB designs, we advocate for a modular deployment strategy, promoting wider adoption at smaller to medium scales and reducing the barriers to initial investment. We anticipate that this modular approach mitigates investment risks and accelerates the adoption of CO₂ capture technologies across various industrial sectors, enabling strategic deployment and operation of CO₂ capture plants such as gradual scale-up or scheduled partial operations.