Onsite nitrogen generation

Nitrogen is a key part of the production process of many industries such as oil and gas, electronics, and pharmaceuticals as well as applications including chemical manufacturing, food and beverage processing and packaging, laser cutting and wastewater treatment and these industries require a reliable supply and quality of the gas.

Atlas Copco Compressor Technique Industrial Air Division business line manager Zandra van der Westhuizen says that the onsite generation of nitrogen, compared to buying or leasing cylinders of liquid nitrogen offers a range of advantages, including reduced cost per unit of nitrogen, diminished logistical problems and the elimination of the hazards of pressurised bottles or liquid gas in the workplace. “So, when it comes to cost-effectiveness, efficiency, total cost of ownership, employee safety and environmental impact, onsite nitrogen generation presents a strong case,” she adds.

The company asserts that the onsite installation of its nitrogen generators ensures that a plant will never run out of nitrogen if there is a constant supply of compressed air. The plug-and-play gas generators are designed to be ready to use with no costly installations. The nitrogen generator is designed as a compact machine with a small environmental footprint and quiet operation.

Atlas Copco’s onsite nitrogen generators can make use of either Pressure Swing Adsorption (PSA) or Membrane technology. PSA technology is regarded as the optimum solution for electronic, chemical and pharmaceutical industries that require high purity levels of up to 99.999% and flow of 1300 Nm³/h as its standard unit, with the option of higher flows if required. PSA generators consist of two connected towers that produce a near-continuous flow of nitrogen. PSA separates nitrogen molecules from the oxygen molecules by trapping oxygen from the compressed air stream using adsorption. Adsorption takes place when molecules bind themselves to an adsorbent – in this case the oxygen molecules attach to a carbon molecular sieve.

Nitrogen generators using Membrane technology can achieve purity levels in the range of 95% - 99.5% (adjustable) and flow up to 500 Nm³/h which is said to be ideal for use in fire prevention, plastic injection moulding and food preservation applications. A Membrane nitrogen generator extracts the nitrogen in the air supplied by a compressor. The compressed air is pushed through a membrane filled with hollow fibres. Oxygen and water vapour dissipate through the fibre walls and are vented out, leaving only the very dry nitrogen inside the fibres, pushed out on the other end of the membrane, ready for use.

With both PSA and Membrane generators, the intake air is fundamental to ensure the purity of air from onsite nitrogen generation. The compressed air that flows into the nitrogen generator needs to be clean and dry. The temperature and pressure of the inlet air must also be controlled by installing an air dryer between the compressor and onsite nitrogen generator. 

“Owing to our ongoing technical innovations, we offer a complete air solution that contributes to optimised production processes at the lowest possible operating and ownership costs with a rapid return on investment,” concludes Van der Westhuizen.