Elements of gas permeation process engineering
Membrane gas separations

Schematically, there are three different types of gas permeation processes:

• single-stage separation (simplest case), often studied as a first approach (figure 12 );

• multi-stage separation (usually limited to 2 or even 3 stages, due to the increasing cost of multiple compressors);

• hybrid process, combining a gas permeation system with another type of process (by far the most complex case).