(339j) Rotating Packed Bed (RPB) for Modular CO2 Capture: Design and Operation Optimization

Rotating packed bed (RPB) is an intensified unit that enhances mass transfer and unit throughput with rotation of packing inside the column. The rotation enables enlarged contact areas between liquid and gas phases and use of high-viscosity solvents, affording a significant reduction in the size and capital cost of separation units. A compact and modularized CO₂ capture process is an exemplary application of RPB. Several experiments and simulation studies support the advantages of applying RPB to the CO₂ capture process, mainly the size reduction of large absorption and desorption columns in a conventional process. The challenge is that there currently is no reported case of commercial-scale application of RPB to the CO₂ capture process, and therefore, it is difficult to examine its viability. In particular, the energy efficiency of the CO₂ capture process can be significantly affected by the design of the RPB units (e.g. inner and outer radii, height) as well as the operating conditions since the mass transfer area and hydrodynamics inside the column vary along the radial axis. Therefore, to fully examine its potential, efficient RPB unit design and operation conditions should first be explored with rigorous modeling and simulation.

This study addresses a simultaneous optimization of the design and operation condition of the CO₂ capture process using RPB columns. A process model for RPB columns with 30wt% Monoethanolamine (MEA) is first constructed in commercial software of gPROMS. Then, the optimal RPB design and operation of the capture process for industrial-scale CO₂ emission sources are explored through optimization, which minimizes the annualized CO₂ capture cost with prudently chosen constraints (e.g. hydrodynamics). By simultaneously optimizing the design and operation condition variables as decision variables, we explore the optimal unit design and operation of a modular CO₂ capture process with RPB.