A modeling study of module arrangement and experimental investigation of single stage module for physical absorption of biogas using hollow fiber membrane contactors

In the present work, the effect of module arrangement on the physical absorption of CO2 and H2S in water at high operating pressure using 2 different types of hollow fiber membrane contactor (HFMC) including polyvinylidenefluoride (PVDF) and polytetrafluoroethylene (PTFE) was studied for biogas upgrading application. The simulation was performed at various liquid velocities (0.12-2.0 m/s), pressure differences between liquid and gas phases (0.125-1.0 bar for PVDF and 1.0-5.0 bar for PTFE), operating pressures (1-30 bar) under four different module arrangement scenarios, i.e., (i) single stage module, (ii) multistage module, (iii) multistage module with splitting liquid (α = 0.2 and 0.4) and (iv) multistage module with recycle liquid (φ = 0.5 and 1). The modeling results predicted the significant improvement of CO2 and H2S removal performances when the multistage module was applied for both HFMCs. To obtain the highest removal performance, the suitable liquid velocity, pressure difference between liquid and gas phases and the liquid flow pattern of the module arrangement are the key concerns. For PVDF, the multistage module with splitting liquid (α = 0.2) provides the highest performance at the liquid velocity of 0.12 m/s, pressure difference of 0.125 bar and the operating pressure of 30 bar. For PTFE, at the liquid velocity of 2.0 m/s and the pressure difference of 1.0 bar, the multistage module with recycle liquid (φ = 1) gives the highest performance at the operating pressure of 1-20 bar while the multistage module with splitting liquid (α = 0.4) provides the highest performance at the operating pressure of 30 bar.