2025 AIChE Annual Meeting

(587m) Hydrodynamic Characterization and Performance Evaluation of a Magnetically Stabilized Fluidized Bed for Enhanced CO? Capture

Authors

Ashin Sunny - Presenter, The Ohio State University
Ishani Karki Kudva, The Ohio State University
Danwyn Aranha, The Ohio State University
Krutarth Pandit, The Ohio State University
Rushikesh Narwade, The Ohio State University
Seth Apau, The Ohio State University
Sudeshna Gun, The Ohio State University
Pinak Mohapatra, The Ohio State University
Dawei Wang, The Ohio State University
Andrew Tong, Ohio State University
Liang-Shih Fan, The Ohio State University
Despite rising renewables, natural gas remains vital for energy but emits significant CO2, driving climate change. This study aims to enhance CO2 capture in Natural Gas Combined Cycle (NGCC) power plants using a magnetic field-supported fluidized bed. The work utilizes energy-efficient solid sorbent-based CO2 capture methods, particularly potassium carbonate, which are cost-effective, exhibit high CO2 sorption capacities, and tolerate moisture in flue gas, making them ideal for post-combustion applications. While several studies have focused on sorbent material design, there has been insufficient attention paid to reactor design for enhancing carbon capture efficiency. Fixed bed reactors are commonly used for CO2 capture but suffer from poor heat and mass transfer, leading to high pressure drops at high flow rates. Fluidizing the bed improves heat transfer but may not enhance mass transfer due to bubble formation. Implementing a magnetically stabilized fluidized bed (MSFB) shows promise in increasing carbon capture efficiency by suppressing bubble formation, thereby enhancing gas-solid contact. This approach also reduces pressure drop across the bed, prevents sorbent carry-over at high flow rates, and minimizes sorbent attrition.

A current-carrying 8-coil cage was designed in COMSOL to generate a uniform magnetic field within the bed. The fabricated cage was installed around the fluidized bed setup, and hydrodynamic testing was conducted with sorbent material K2CO3 supported on Al2O3, impregnated with magnetic iron (Fe). The hydrodynamic study investigated the effect of magnetic field strength, Fe loading, particle size, and gas velocities on bed pressure profiles. Regime maps of superficial gas velocity versus applied magnetic field strength were developed for different particle sizes and Fe loadings to determine operating conditions for different regimes. Results showed decreased pressure fluctuations when the bed entered the stabilized regime compared to when no magnetic field was applied, validating bubble suppression and enhancing gas-solid contact. Following this, CO2 capture from flue gas streams using K2CO3-Al2O3-Fe sorbent was evaluated across various reactor configurations - fixed bed, fluidized bed, and MSFB (magnetically stabilized, magnetic bubbling) - at the same weight hourly space velocity (flue gas flow rate to weight of K2CO3). Performance across the different configurations was assessed based on carbon capture capacity and CO2 removal fraction. The MSFB reactor demonstrated higher carbon capture capacities due to the improved gas-solid contact achieved by suppressing bubbles. Compared to conventional fluidized beds, MSFBs also exhibited superior CO2 removal fractions.

This study validates the advantages of magnetic stabilization in fluidized beds for industrial processes requiring efficient gas-solid contact. The insights from material and reactor design could also enhance CO2 capture technologies, including direct air capture, to combat climate change.