Thermal effects on breakthrough curves of pressure swing adsorption for hydrogen purification

• A multicomponent adsorption, heat and mass transfer model is implemented in Comsol.
• Experiments on activated carbon bed and zeolite 5A bed are used to validate the model.
• Two ternary H2/CH4/CO mixtures and one quaternary H2/CO2/CH4/CO mixture are studied.
• Parametric studies of feed rate, dispersion, adsorbent and adsorbate are performed.
• Adiabatic, isothermal and general heat transfer boundary conditions are analysed.

Applying pressure swing adsorption (PSA) to recover hydrogen from industrial exhaust gas is an effective way to recycle by-product industrial exhaust gas. In this paper, the PSA process for hydrogen purification is studied using a one-dimensional multicomponent adsorption, heat and mass transfer model which is implemented in Comsol Multiphysics version 3.5a. This model is validated by experimental data on activated carbon (AC) and zeolite 5A bed. Both the breakthrough curve and the bed temperature distribution show good agreement with experiments. This paper considers two hydrogen ternary mixtures (H2/CH4/CO = 60.4/28.1/11.5 vol% in activated carbon bed; H2/CH4/CO = 60/30/10 vol% in zeolite 5A bed) and one hydrogen quaternary mixture (H2/CO2/CH4/CO = 69/26/3/2 vol% in activated carbon bed). The purpose of two ternary mixtures (H2/CH4/CO) that are fed into an activated carbon PCB bed and a zeolite 5A bed respectively is to study the influence of adsorbent on the breakthrough characteristics of the mixture. The quaternary mixture (H2/CO2/CH4/CO) is fed into an activated carbon bed aimed at investigating the effect of mixture composition on adsorption performance. The thermal effects associated with the adsorption process are examined by comparing various thermal boundary conditions: adiabatic, isothermal and general heat transfer boundary conditions. The results suggest that good control of bed temperature is an effective way to restrain thermal effects on breakthrough curves. The operating parameters of feed flow rate and axial mass dispersion coefficient are also examined.