Costs shrink through technology advances

On-site nitrogen generation offers manufacturers and metal processors many advantages over traditional supplies of gas in cylinders. John Davis writes.

On-site nitrogen generation 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.

Equipment payback times have shrunk commensurately, Parker domnick hunter in Australasia product sales manager John Davis said.

Older generators using PSA (Pressure Swing Adsorption) and membrane separation technology were usually very 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 far more compact, cost efficient and suitable for smaller manufacturers 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.

World wide applause

Being introduced to Australia as part of a global launch by Parker domnick hunter (which operates in more than 80 countries) 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.

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 to name a few.

Parker domnick hunter Filtration

John Davis

0418 352 407

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