Simulation of a membrane air separation unit using industrial process simulators

Nowadays, membrane processes are widely used for high purity Nitrogen production. Separation of air by membranes is a flexible process in which the investment and operational costs are lower than for example adsorption or cryogenic processes. Such processes are based on relative permeability of air components which are transported by the pressure difference between two sides of the membrane. Mathematical equations for modeling and simulation of membrane air separation were solved by both HYSYS simulator without any need of external programming out of the simulator environment, and linking Excel to ASPEN PLUS without any need for compile or multiple processes. Countercurrent flow conditions through the membrane, and hollow fiber type membrane were assumed to be applicable. By doing such simulation, the separation percentage of air components in two product streams, and also purity percentage of each stream could be determined. Results of simulations by these two industrial simulators were compared with experimental data and a good consistency was reached. The proposed method can be used for simulation of non-ideal systems successfully.