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Simulation and Experimental Study of Simultaneous Methanol Recovery and CO2 Capture in Rotating Packed Beds

Hamidi, Amir Hossein | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58249 (06)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Eini, Saeed; Farhadi, Fatollah; Hosseinpour, Vahid
  7. Abstract:
  8. In methanol production units, a portion of the produced methanol is lost along with the off-gas streams, which also contain valuable gases such as methane and hydrogen. In addition to methanol, these waste gas streams contain a significant amount of carbon dioxide. On one hand, recovering methanol is economically important; on the other, removing carbon dioxide not only increases the purity and calorific value of the gas stream containing methane and hydrogen but also contributes to reducing greenhouse gas emissions from an environmental perspective. Therefore, developing processes for the simultaneous absorption of methanol and carbon dioxide can offer considerable economic and environmental benefits. A common approach for this purpose involves water scrubbing in packed absorption columns, followed by carbon capture using amine-based solvents. However, such systems require multiple units and high energy consumption. In recent years, intensified process technologies such as rotating packed beds (RPBs) have attracted attention due to their compact design and reduced operating costs. In this study, the performance of a rotating packed bed was evaluated for the simultaneous absorption of methanol and carbon dioxide from a waste gas stream. Computational fluid dynamics (CFD) simulations were conducted to analyze gas-phase pressure drop and liquid holdup, and the results were validated against empirical correlations. In addition, mass transfer simulations were performed, showing a maximum deviation of 12% compared to experimental results. Simulation results indicated that methanol recovery increased with higher rotational speeds and liquid flow rates, while CO2 absorption increased up to 900 rpm and then declined, which could be attributed to reduced liquid residence time. Subsequently, a lab-scale RPB reactor was constructed, and experimental tests were carried out. Contrary to the numerical results, the experiments showed that increasing the rotational speed and amine solution flow rate enhanced CO2 absorption, while methanol absorption remained nearly constant. Finally, a performance comparison between this system and a fixed packed bed simulated in Aspen HYSYS revealed that CO2 absorption efficiency improved from 58% in the fixed bed to 98% in the RPB, while methanol recovery increased from 98% to over 99%
  9. Keywords:
  10. Rotating Packed Bed Reactor ; Process Intensification ; Computational Fluid Dynamics (CFD) ; Carbon Dioxide Capture ; Carbon Dioxide Absorption ; Waste Gas Recovery

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