What is a Membrane Nitrogen Generator?

How does a Membrane Nitrogen Generator work?

The PMNG Cabinet Series membrane nitrogen generator is a modular system consisting of pre-filtration, separation, and distribution sections. Controls for the system are included in the nitrogen separation unit.

Ambient air enters the feed air compressor, which is typically an oil injected rotary screw air compressor via its inlet filter. Air is compressed and travels through an aftercooler and, in most systems, a refrigerated air dryer.

Inside the PMNG membrane nitrogen generation unit, the first item the feed air comes in contact with is the 6-Step filtration system, which utilizes a combination of particulate, coalescing and carbon adsorption technologies. Oil carryover from system is expected to be in the 2 parts per billion range, with maximum solid particle size .3 micron. All filters are fitted with automatic condensate drains. Most units are fitted with the air circulation heater and controls, and is installed in the air stream before the nitrogen membrane(s) but after the final filter and pressure regulator. This heater maintains a constant temperature of compressed air to the membranes enhancing stability and performance.

The nitrogen membrane module(s) are located in the heated air stream. On lower purity, multiple module systems 99% and below, the membranes are connected in parallel. On higher purity, multiple module systems 99% or higher, they are connected in series or combination of series and parallel. High purity systems have separate permeate connections. One is strictly waste gas, but the second one is a line that can be re-circulated back to the feed compressor intake to enhance purity and productivity. After the air passes through the membrane bundle(s) it is essentially nitrogen plus trace amounts of inert gasses and the specified oxygen content. A built-in flow meter is there to constantly monitor nitrogen flow.