Nitrogen Generator operation using PSA

Nitrogen separation with PSA is a simple process. Moreover, there are few moving parts, and the material is regeneratable. This means one can produce a limitless supply of N2 without the need of repurchasing active ingredients or filters. I will now describe the operation of the PSA before I go into the construction.

A 6 HP standard compressor draws air through a scrubber at a flow rate between 6 and 9 SCFM depending on the pressure. The scrubber contains 13x molecular sieve in order to remove H20 and CO2. I run the compressed gas though a water-cooled coil and into a 30 gallon storage tank. This provides a large reservoir of compressed gas for when the PSA vents the exhaust gas. This allows the device to quickly reach a high pressure for the CMS to function properly.

The compressed, water and CO2-free gas goes through two filters. The first removes remaining water vapor and large particles (1 um). The second is a 0.01 micron filter. This is necessary to protect the CMS material from getting clogged with micro-debri. A pressure gauge monitors the pressure entering the system and the compressor has a 150 psi pressure-release valve.

A pneumatic valve controls the flow of the gas into one of two towers made of steel. The towers contain the CMS. Steel mesh and filter paper prevent the material from pouring out, while allowing for gas flow. When the valve is open to the tower bed, the pressure drives the O2 into the CMS pores. Meanwhile, O2 waste vents out of the second tower bed, regenerating the second bed. As the first bed feels the pressure, enriched N2 leaves through the bottom of the tower through a one-way check valve.

A controller monitors how long the system pressurizes the bed. My system usually reaches a pressure of 110-120 psi. After 110 seconds, a second valve opens allowing fresh gas to pressure bed two. This also allows some of the pressurized gas from bed one to help pressurize bed two. After 0.5 seconds, the valve to the first bed closes and vents the exhaust gas, rich in O2, to the atomosphere, regenerating that bed. The cycle endlessly repeats.


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