Gas separation membrane with partial surfactant coating

Abstract

A gas separation module includes fibers formed of a membrane which exhibits selectivity between gaseous components to be separated. The fibers are partially coated with a solution which enhances their selectivity, the fibers being uncoated in the vicinity of their feed ends. The partially coated fibers provide a good compromise between the goals of improved selectivity and enhanced product flow. The gaseous component that permeates through the membrane is made to flow in a direction opposite that of the main gas feed, due to a baffle that directs the permeate in the desired direction. The invention also includes a method and apparatus for making the partially coated module.

1 . Apparatus for enhancing performance of a gas separation module, the module having a feed end and a product end, the module including fibers made of a gas separation membrane, the fibers extending from the feed end to the product end, the apparatus comprising: 
 a) a reservoir for storing a solution which enhances selectivity of the gas separation membrane, the reservoir having an outlet connected to a valve,    b) a gas separation module having a plurality of fibers extending from a feed end to a product end, the module being in fluid communication with the reservoir, the module being mounted with the product end oriented down and the feed end oriented up, and    c) means for vertically adjusting a position of the reservoir, so as to adjust a liquid level in the module, wherein the fibers of the module are partially coated with said solution, and wherein the fibers remain uncoated in a vicinity of the feed end.    
     
     
         2 . The apparatus of  claim 1 , further comprising a drain valve, connected to the module, for draining the solution from the module when a coating operation is complete.  
     
     
         3 . The apparatus of  claim 2 , wherein the apparatus further comprises a conduit for directing a drying gas towards the module, the conduit being connected to the feed end of the module.  
     
     
         4 . A method of enhancing selectivity of a membrane-based gas separation module, the module having a feed end and a product end, the module including fibers extending from the feed end to the product end, the fibers being made of a membrane exhibiting selectivity between gaseous components to be separated, the module including means for directing a permeate gas in a direction opposite that of a main feed stream, the method comprising: 
 a) mounting the module vertically with the product end facing down,    b) partially filling the module with a solution which enhances selectivity of the membrane, the filling being accomplished by opening a valve connecting a reservoir with the module, wherein levels of solution in the module and the reservoir become equal, and wherein portions of the fibers of the module, in a vicinity of the feed end, are not submerged in the solution, and    c) adjusting a vertical position of the reservoir so as to adjust a proportion of coating of the fibers of the module.    
     
     
         5 . The method of  claim 4 , further comprising draining the solution from the module, and drying the module by passing a dry gas through the module.