Membrane Separation System

Nitrogen membrane system is another popular non cryogenic technique of air separation. Using this system, air is filtered through a membrane, removing oxygen, carbon dioxide and water, thereby producing inert nitrogen.

 

How it Works ?
The system separates gases by using the principle of selective permeation across the nitrogen membranes wall. The rate of permeation of each gas is measured by its solubility in the nitrogen membrane material for nitrogen polymeric membranes while the rate of diffusion is dependent on the molecular free volume in the nitrogen membrane wall. Gases that are small in molecular size and display high solubility in the nitrogen membranes permeate faster than larger, less soluble gases. The system consists of tube bundles made of special polymers configured in a manner similar to a shell and tube heat exchanger.

 

Different gases pass through the film depending on the permeation rates. Products like oxygen (plus water vapor and carbon dioxide) are "fast gases" that pass more fast through the tube walls compared to "slow gases" like argon and nitrogen. This allows dry air to be transformed to a product which is a kind of mix of mostly nitrogen gas and argon, and impure products are vented out from the shell. Nitrogen product emerges from membrane units and since there are no moving parts in the separation process, these units can be easily activated when required and shut down when they are not.

 

This system of air separation is considered to be the most cost effective for relatively low demand applications. However it is also used today at higher production rates. This has been made possible by manufacturers increasing the physical size and production capacity of their largest modules.

 

Components of Nitrogen Membrane System

Tags:- Membrane Separation Processes, Nitrogen Membrane System

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