4 minute read • published in partnership with Atlas Copco
Case Study: Atlas Copco on-site nitrogen generation solves laser cutter’s bulk supply problem
Manchester-based Concept Metal Products offers some of the largest laser cutting and sheet metal folding capacities in the UK. Until recent times, the company has relied on the bulk supply of liquid nitrogen as an essential element of its laser cutting process operations. But when the supplier declared it was unable to fulfil its contractual obligations, an alternative and reliable nitrogen source had to be sought immediately to avoid major downtime and loss of business opportunities.
The bulk supply problem
Before its nitrogen supply was summarily suspended, the company’s production cycle, based on a 10 hours per day/4days a week shift pattern, had been consuming a maximum 4500m3 of nitrogen a month from the delivered bulk supply to feed two 6kW and one 4kW laser cutters. This was costing 18.11p per m3 for the gas alone. When the supplier’s environmental, bulk supplementary, and hazardous goods delivery charges were added on, the price per m3 amounted to 28.79p, a total cost of well over £15,000 a year.
As the delivery of liquid nitrogen became unreliable, Concept Metal Products was often left without supply, not knowing when the next delivery would be. After reading an Atlas Copco social media post, Concept Metal’s general manager, Dean Barnard, became aware of the possibility of generating nitrogen on-site. The answer to his supply hiatus turned out to be installing an energy-efficient Atlas Copco HPN2 on-site nitrogen generation system. This would ensure an independent, reliable and continuous supply of high-purity nitrogen – and achieve substantial cost savings.
Atlas Copco proposed its high-pressure nitrogen package, an all-in-one, plug-and-play nitrogen generation system that provides gas supply independence and cost savings. Initial recommendations looked to utilise the HPN2 SKID 6 system; however, it was soon realised that the flexibility and storage capabilities would allow for the company’s productivity to be boosted by the HPN2 SKID 8 system. This complete nitrogen generation system on a compact skid includes a GA22VSD+ compressor utilising VSD technology, an NGP100⁺ nitrogen generator, air and nitrogen receivers, booster, dryers, filters and a high-pressure bottle bank for storage. The nitrogen skid package is ready to work upon arrival, and one input and one output ensure easy installation and commissioning. The system supplies Concept Metals with 38Nm3/hr of nitrogen at 99.99% purity, storing 240m3 of nitrogen onboard as standard.
The addition of a second bottled bank allowed Concept Metals to store up to 480m3 of nitrogen onsite, enabling the company to take advantage of a favourable off-peak energy tariff by filling up their nitrogen onsite overnight, ready to be used again the next day. The system can also operate during the day to provide additional nitrogen and fill storage in periods of low and no demand.
As Dean Barnard, General Manager of Concept Metal Products explains: “We already had a favourable off-peak energy tariff that allowed us to work from 7pm until 7am, but with this new on-site system on board, we saw the cost of nitrogen reduced to as little as 7p per m3. That meant the supply expenditure was down to approximately £3,780, a quarter of our previous annual £15,000 outlay, so we could afford to increase output and service to our customers who were dependent upon our capabilities for their specialist metal applications.”
He went on to describe those specialisms as pressed metal sections, laser cutting, and bending up to a length of ten metres, as well as welded assemblies, an output to UK industry sectors that includes public service and commercial vehicles, nuclear, water, power, and waste disposal applications: ”We have supplied stainless steel parts for the Olympic Fountains in Barcelona, items for the Millennium Dome site and the main components for the fire doors at the new international airport in Hong Kong”.
The company also offers basic drilling and tapping, bevelling, and welding for mild steel, stainless steel, and aluminium as well as subcontract services such as powder coating, plating, plasma cutting, and water jet cutting.
NGP generator’s PSA operation
The NGP25+ nitrogen generator at the heart of the Concept Metal Products skid package is part of Atlas Copco’s NGP/NGP+ range of service-friendly nitrogen generators, which combine high flow capacity, exceeding 3000 Nm3/h, with low operating and maintenance costs. Fully automated, with oxygen monitoring as a standard feature, the units require no specialist installation or commissioning.
The generators operate with Pressure Swing Adsorption (PSA) technology that works by separating nitrogen and oxygen molecules within the compressed air stream feeding the unit. PSA does this by trapping the oxygen using adsorption techniques. Adsorption takes place when oxygen molecules attach to a carbon molecular sieve (CMS) allowing the smaller nitrogen molecules to pass through.
Whereas other competitive systems require six volumes of air to produce one volume of nitrogen, Atlas Copco’s generator design requires a ratio of only four parts of air to one part of nitrogen.
Dean Barnard has been very impressed with the performance and benefits that on-site nitrogen generation offers: “There’s no doubt it is a far more dependable and cost-efficient solution than having to rely on an expensive bulk liquid supply with all its transport and handling problems as well as the dependence upon suppliers’ delivery scheduling. Also, the quality of the nitrogen that is produced by the generator exceeded my expectations.”
He was equally impressed with the level of service and support he received from the Atlas Copco sales and engineering teams and the speed of their response to his requirements: “I cannot fault them. Within three weeks from our final on-site generation system decision, the units were installed, and thanks to the teams’ professionalism, just two days after that we were up and running.”