On-site nitrogen generation offers manufacturers and metal processors many advantages. It is particularly suitable for processes requiring consistent supplies of the inert gas, including carburising and carbonitriding, tempering and annealing, gas quenching, laser profiling, neutral hardening, galvanising and normalising.
Not only does on-site generation avoid production interruptions as cylinders are changed with associated quality, cylinder handling and potential OHS issues, but also the technology needed to produce it on-site has shrunk in size and complexity over recent years.
Older generators using PSA (Pressure Swing Adsorption) and membrane separation technology were usually large and designed to support big customers with a high demand for nitrogen gas. The latest on-site nitrogen generation technologies, such as the MAXIGAS nitrogen generation system from Parker domnick hunter , are compact, cost efficient and suitable for smaller manufactures and metal processors.
These generators use carbon molecular sieve pressure swing (PSA) for optimum purity and reliability of supply of commonly used nitrogen. This technology can be set to supply nitrogen from 97% to 10 parts per million (99.999%) and incorporates a self-regeneration feature to minimise maintenance.
Being introduced to Australia as part of a global launch by Parker domnick hunter, MAXIGAS generators are a proven technology, having been used in more than 10,000 installations worldwide. The latest MAXIGAS units are constructed in pairs of extruded aluminium columns filled with carbon molecular sieve (CMS) material.
Operating on the pressure swing adsorption principle (PSA), the two columns function alternately, with one side producing gas while the other regenerates itself. The side of the unit being pressurised by compressed air produces a continuous stream of nitrogen, which passes through the CMS while oxygen and other trace cases are adsorbed by it.
The carbon molecular sieve differs from ordinary activated carbons in that it has a much narrower range of pore openings. This allows smaller molecules such as oxygen to penetrate the pores and be separated from the air stream. The larger molecules of nitrogen bypass the CMS and emerge as high purity gas. Purities are determined by the velocity at which the air passes through the CMS columns.
At a pre-set time, before the online bed is saturated with adsorbed gases, the system switches to regenerative mode, venting the contaminants from the CMS. As this happens, the second CMS bed comes online and takes over the separation process to ensure uninterrupted nitrogen production. An in-built oxygen analyser with alarm function ensures only gas of the required purity is delivered to the storage vessel.
Parker domnick hunter MAXIGAS nitrogen generator packages produce a continuous supply of nitrogen gas from compressed air. After the equipment payback period, this eliminates a large part of the cost of gas supplies. Environmentally responsible manufacturers also appreciate the fact that producing their own supply of nitrogen on site eliminates the need for continuous cylinder deliveries by road transport.
Diverse applications for on site MAXIGAS nitrogen generators range from Modified Atmosphere Packaging (MAP) of foods to preserve their freshness, through to wine and beverage sparging, tyre inflation, lasers, void formation in plastics production, metals treatment, wire production and wave soldering.