Due to a need for lots of pure nitrogen gas for another project, it was decided to go about building a nitrogen separation system. This device is designed to compress atmospheric air, dry and filter the compressed air, and then separate out the nitrogen gas from the remaining atmospheric gases (mostly oxygen and argon).
The main concept behind the separator is to force filtered air through a nitrogen separation membrane, which is simply designed to separate atmospheric oxygen and argon from the nitrogen in the air. The rest of the project is consistent of gas compression, regulation, and filtering.
The nitrogen gas being generated in this project needs to be mostly pure along with being clean and dry because it will be used in a nitrogen liquefier. Any water of oil contaminating the gas can freeze in the liquefier and clog pipes. The retaliative purity of the gas being generated can be adapted for different types of projects.
To obtain dryer gas, add more Oil/Water separators and desiccant dryers. To obtain less pure gas, use a less accurate nitrogen separation membrane (in theory the only reason you would do this is to reduce cost).
The whole project is deigned to be built with parts costing less then 400 dollars, but that depends on the availability of certain higher priced items. For example, I already had a old compressor that I wasn't using, so I chose to use that instead of buying a new one. A further note on the compressor, one can choose to use their shop compressor rather then a dedicated one, just keep in mind the noise level. Due to the slow output rather, the separator can be left on anywhere from a few hours to more the several depending on the amount of nitrogen needed. With that rate, a shop compressor might be going off every 20 minutes or so. Another option is to use a refrigeration compressor instead but this requires more filters and an oil return line due to the lubricant usually being mixed with the refrigeration gas.
The project logs below will outline the building aspect of the project as it is built. Details for the design are directly below.
Design:
The flow of the working gas through the system is as follows: