| Dehydration process based on hollow fiber membranes is one of the crucial and effective methods to remove water vapor from industrial gases such as natural gas, compressed air and so on. Taking into consideration that water vapor is a micro- concentration, condensable and high permeability component in gases, the permeation behaviors and some key factors influencing the dehydration process were investigated. First, some specific behaviors of water vapor through dense polymer membranes (e.g. polysulfone, blend of polysulfone/sulfonated polysulfone and silicone rubber), cluster mobility and swelling, were discussed. Due to the effects of the two specific characteristics, the relationship of permeability coefficients, diffusion coefficients and solubility coefficients of water vapor in polymer membrane vs. feed pressures (activity) and operation temperatures are significantly different from that of permanent gases (H2 and N2 et al.) Resistance distribution of water vapor through PSF/silicone rubber composite membrane was studied by a resistance model and experiments. The important role of support layer on water vapor permeation has been demonstrated. And several ways to increase water vapor permeation coefficient and selectivity with other gases were also given by optimizing structure parameters of membrane. In terms of membrane dehydration process, some factors including pressure drop in 3 lumen, dimension of hollow fiber, membrane performance and operation conditions were discussed by a simulation model. An industrial scale pilot test system was established for natural gas dehydration, and the experimental results are quite consistent with those of simulation. Moreover, the dew point of water vapor and recovery of methane meet the requirement of application. Additionally, some guidance to preparation of membrane, improvement of membrane separator and optimization of operation conditions in dehydration process was put forward.
|
PDF Full Text Request