Pervaporation membrane process is a membrane separation process that can separate liquid/liquid mixtures, while Vapor permeation membrane process is a membrane separation process that can separate vapor/vapor or vapor/gas mixtures. These two membrane separation processes differ only in the shape of feed mixture to be separated, but they are the same membrane process, using a non-porous polymer membrane. The hollow fiber type pervaporation/vapor permeation membranes are reinforced by a braid of polyester, which have been developed by SepraTek's new technology. A hollow fiber form of pervaporation/vapor permeation composite membranes utilizes the significant benefits of hollow fiber membrane shape; high membrane packing density in module, low fabrication cost, and flexibility in membrane module design, so that the hollow fiber membranes can be applied in various fields. SepraTek™ hollow fiber composite membranes consist of a braid structure of reinforcement, a porous support layer, and an active layer on the porous layer. The braid fabrics are fabricated by braiding polymeric fibers and metal wires together, so SepraTek hollow fiber composite membranes reinforced by the braid possess an excellent pressure-resistance as well as a good dimensional stability in organic solvents even at high temperature.

All hollow fiber membranes in the module are reinforced with polyester woven braid on the outside, and the feed liquid flows lumen side of hollow fiber and a vacuum is applied to the outside of the hollow fiber, i.e. on the shell side. In this case, the porous support layer and the braid layer act as an insulator, and moreover, vacuum applied at the outside of hollow fiber of the hollow fiber membrane retards heat transfer from the feed to its surrounding. As a result, the heat loss of the feed into the surrounding is very low, and thereby the case of membrane module would not be heated to a great extent by feed mixture of an elevated temperature. In addition, the braid layer with high porosity exists between the hollow fiber membranes and acts as a spacer, so that the vacuum applied is well transmitted to the outer surface of each hollow fiber and maintains a high degree of driving force. The materials of the module case are chemically resistant plastic, FRP and metal, etc., and the module potting resin uses epoxy resin with excellent heat resistance and chemical resistance.

In order to apply vacuum effectively to the permeate side of respective unit membrane module and to simplify piping in configuration of unit membrane modules, a number of unit modules are packed into a body 'module assembly' in fabricating a large scale of pervaporation system. The number of unit modules in a membrane assembly can be determined, depending on the hydraulic characteristics of feed liquid, the scale of pervaporation system, separation extent to be achieved, and so on.

SepraTek can design and supply permeable pervaporation/vapor permeation membrane separation systems in conjunction with or without the distillation process. This membrane separation system enables the separation of water/organic mixture without the high energy required to separate the mixture at the azeotrope point, such as liquid/liquid extraction and water washing. This SepraTek permeation evaporation/vapor permeation membrane separation process has the following features: