NITROGEN is used for industrial processes as diverse as winemaking, beer dispensing, extended life packaging for foodstuffs, plastics void production, metalworking, tyre inflation, lasers and wave soldering, to name a few.
But until quite recently, convenient, safe and inexhaustible on-site generation of nitrogen was a rarity. Now the picture is changing.
First introduced internationally in the 1960s, nitrogen gas generators used pressure swing technology (PSA) and membrane separation technology to produce non-cryogenic nitrogen on site.
Generators were usually very large and were designed to support key customers with a high demand for nitrogen gas. Occasionally, gas generators were also used to supply nitrogen to customers in remote locations.
In the 1980s and 1990s, some gas companies realised there was an opportunity to advance the concept of on-site gas generation and develop small-scale systems that would replace traditional nitrogen supplies, such as compressed gas cylinders and liquid nitrogen dewers.
The major gas producers were interested in the idea, but most viewed it as a threat to their lucrative gas cylinder business. It was therefore left up to the gas generator manufacturers to introduce their products directly to end users.
The advantage of this was that customers were often quick to see benefits of a gas generator, compared with cylinders. They liked the cost savings, convenience and increased safety this alternative provided by dispensing with multiple handling of bulky and costly cylinders.
The applications for gas generators have expanded dramatically since their inception. Today PSA and membrane-based nitrogen generators provide gas to applications such as those listed above and many more.
And now that gas generation technology has become established, and there is greater acceptance at the end user level, some of the major gas companies have shifted their position and have incorporated gas generators into their portfolio of supply options.
Recognising that generators are just another way to supply nitrogen, the gas companies began to offer them to customers when it was deemed to be the most effective supply method or when a customer had a genuine preference for a gas generator, for whatever reason. This approach kept the customer happy and, more importantly, retained their business.
Today on site gas generation is widely used in many industry sectors, which rely on ready-made supplies of nitrogen or other industrial gases, to feed production facilities. For many, this method of production is tried and tested and proven both reliable and economical. In fact for many, on-site gas generation is now nothing new.
Increasingly, however businesses in many different industries have started to reconsider their gas supply arrangements and explore the benefits that on-site gas generation brings, including reduced costs, increased quality, faster process times - and all without the responsibility of managing cylinder replacements, delivery, storage and up-keep.
In Australia, these industries have ranged from foundry operations to olive producers, from snackfoods to vehicle component manufacturers. Their new approach is helping them achieve the competitive edge they are seeking, while staying focused on core manufacturing activities.
In addition to these new management solutions, recent technological advances, which have made nitrogen PSA systems more modular in design, have helped to make on-site gas generation a more viable alternative for a wider variety of manufacturers.
By tailoring solutions to specific requirements, the latest gas generation systems are capable of driving efficiency and optimising production as well as providing valuable management benefits.
For applications where nitrogen is critical to production, the benefits of on-site gas generators are obvious. On-site generators can halve the cost of alternative gas supplies and continuity of supply is assured.
In addition, on-site gas generation brings environmental benefits including reduced tanker and truck deliveries and lower specific energy consumption.
In addition to the advantages of gas generators from a customer's viewpoint, gas supply companies may also choose to install a system at their customer's site for any number of other reasons, including the fact that delivery to the end-user may be difficult or too costly.
For example, costs to deliver gas within a heavily congested area such as a major city may actually exceed revenue from the gas sales because of the time taken to physically make the delivery.
Also, customers may be located a great distance from the nearest gas distribution depot or scheduled delivery route. In both these instances, a gas generator that provides the purity of gas required would help to minimise distribution costs.
Some gas companies have taken this philosophy even further by introducing a strategy whereby they deliver gas cylinders only within a certain radius of distribution depots (120km radius for example, which is easily exceeded in Australia). Outside this radius, they know the distribution costs become too high and, as a result, will actively consider replacing cylinder or tank supply with on-site gas generators.
In some situations, people use generators to differentiate themselves in the marketplace and gain a competitive advantage. One of the best examples of this can be found in beer dispensing. Currently, two gas mixtures are typically required within a bar or restaurant to dispense beer (nitrogen and carbon dioxide).
As a consequence of installing a mixed gas dispensing system, transportation and distribution costs are dramatically reduced, and provide the distributor with a competitive advantage.
Another benefit is that fewer gas cylinders are required overall, therefore helping to minimise the challenges of managing a large fleet.
When such systems are installed, the distributor also has a secure revenue stream, since the end-user typically enters into a five-year lease agreement for the equipment as well as for the CO2 gas supply.
Gas generation technology has become more widely accepted as a reliable alternative to traditional supply methods. End-users like the convenience of generating the gases that they need on site.
Gas distributors also embrace the technology when they make economic analysis and realise that it is not a threat to their business. Rather, it complements their product offering.
There is now a real momentum and demand for nitrogen gas generators. On-site gas generator manufacturers such as domnick hunter have the experience to partner current and future applications across a broad range of industries.
New CMS technology advances on-site generation
One of the latest on-site technologies uses carbon molecular sieve PSA for optimum purity and reliability of supply of commonly used nitrogen.
This technology is being introduced to Australia and New Zealand by global gas and liquid filtration, purification and separation specialist domnick hunter, whose on-site generators use carbon molecular sieve (CMS) technology to produce high purity gas from compressed air.
The domnick hunter MAXIGAS nitrogen generation system - which can be set to supply nitrogen from 97% to 10 parts per million (99.999%) - incorporates a self-regeneration feature to minimise maintenance.
Being introduced to Australia as part of a global launch by 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.
How CMS works
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.
CMS technology is state-of-the-art for purity of on-site gas production, and is largely maintenance-free in operation, provided it is protected against water, oil and oily gas vapours, which are the enemy of sieve technology and membrane technology alike.
Installation is simple and proven. The MAXIGAS design means that if users want more gas, they simply add extra banks of generators.
The technology has won recognition in the Millennium Products Award introduced through the British Design Council by UK Prime Minister Tony Blair.
* John Davis, is Business Development Manager for domnick hunter Australia, which has doubled the size of its Australasian headquarters to cope with expanding demand for its advanced technologies, including gas generation, breathing air purification, sterilisation of process liquids, water chillers and compressed air treatment products.