Simulation of CO₂ and H₂S Removal Using Methanol in Hollow Fiber Membrane Gas Absorber (HFMGA)

Majid Mahdavian, Hossein Atashi, Morteza Zivdar, Mahmood Mousavi

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DOI: 10.4236/aces.2012.21007                

Abstract

Application of methanol solvent for physical absorption of CO₂ and H₂S from CO₂/H₂S/CH₄ mixture in gas–liquid hollow fiber membrane gas absorber (HFMGA) was investigated. A computational mass transfer (CMT) model for simulation of HFMGA in the case of simultaneous separation of CO₂ and H₂S was developed. The membrane gas absorber model explicitly calculates for the rates of mass transfer through the membrane and components concentration profiles. Due to the lack of experimental data in the literature, the model was validated using available individual components’ water absorption data. The numerical predictions were in good agreement with the experimental data. The effects of operating conditions such as liquid velocity, gas velocity, temperature and pressure were analyzed. It is shown that methanol solvent can successfully be used for CO₂ and H₂S removal in membrane gas absorber. Also it is found that the concentration distribution of CO₂ and H₂S in the gas phase along the fiber length obeys plug flow model whereas in the methanol absorbent deeply affected by the interface concentration, absorbent velocity and diffusivity. In addition, it is shown that application of membrane gas absorber using methanol absorbents for H₂S removal and at higher flow rate is more efficient. Moreover, at operating pressures above 10 atm even at low absorbent rate, H₂S concentration depletion is relatively complete while at 1 atm this value is about 30%. This means that removal efficiency decreases with an increase in temperature and it is more important especially for H₂S.

Keywords

Computational Mass Transfer (CMT); Membrane Gas Absorber; CO2 and H2S Separation; Physical Absorption; Methanol

Conflicts of Interest

The authors declare no conflicts of interest.

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