On-site gas generation is nothing new to manufacturers and processors in many industry sectors, which rely on regular supplies of ultra high purity (UHP) nitrogen or other industrial gases, for their production facility. For many OEMs and processors this method of production is tried and tested and has proved both reliable and economical.
However, increasingly, competition is forcing some forward-thinking manufacturers to reconsider this arrangement as they explore new ways to benefit from quality on-site UHP gas supplies, without the responsibility of on-site management and up-keep. This new approach to on-site gas generation can help them to 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 them more modular in design, have helped to make on-site gas generation a more viable alternative for a wider range 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.
Gas for glass
For one world-leading glass manufacturer, Pilkington, plans to increase production at its flat glass production plant in Gladbeck, Germany, provided an opportunity to review its approach to on-site gas generation. Pilkington's Gladbeck site produces two brands of specialist flat glass for applications in the building and automotive industries: Pilkington Optifloat and Pilkington Optiwhite. The latter is an exceptionally clear glass, sought after by designers and architects, and has been used in prestige construction projects all over Germany including the Reichstag dome in Berlin.
Specialist glass-making processes are extremely sensitive to oxidisation and for this reason, float glass processing usually takes place in a controlled atmosphere, which requires large quantities of very pure nitrogen.
Flat sheets of glass are cut from a continuous ribbon of glass, which is formed by pouring molten glass onto the surface of a bath of molten tin. A nitrogen atmosphere above the tin bath, maintained at less than 5ppm oxygen, prevents oxidation of the tin and ensures a high quality end product.
Benefits of on-site gas generation
For such applications, where nitrogen is so critical to production, the benefits of on-site gas generation 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 some environmental benefits, due to reduced tanker deliveries and lower specific energy consumption.
Until now Pilkington's Gladbeck site had operated and maintained its own air separation unit. This unit produced around 90tonnes of high purity nitrogen a day for its two float glass lines. However, plans to significantly increase production at Gladbeck, meant this would no longer be enough and up to 105tonnes a day was needed.
The time was right to review the plant's existing gas generation system and consider a new approach altogether. An independent assessment was carried out and our own gas management experts revealed that, in order to meet the gap in supply, the plant would need up to five tanker deliveries of nitrogen a day.
At the same time, the independent plant assessment concluded that the existing gas management system was inefficient, expensive to run and due to its age, becoming increasingly less reliable.
When looking for a new gas generation solution, Pilkington focused on efficiency and environmental benefits and was also keen to outsource the management and maintenance of the system, so that its own managers could focus on core glass manufacturing and processing activities. We specified a high capacity on-site generator, capable of meeting the increased demand for nitrogen, with a linked oxygen-monitoring system so we could monitor the all important oxygen levels, to ensure production criteria are being met. One of the benefits of the PRISHPN system is the oxygen content of the gas supply can be controlled as low as 2ppm, well below the limit specified by Pilkington.
We also agreed to maintain the generator and its performance is remotely monitored to ensure maximum reliability. Regular production reports are provided for plant supervisors, permitting continuous monitoring of plant performance and nitrogen production.
Our solution has not only been able to reduce the cost of nitrogen used on site by 40percent, Pilkington is now benefiting from outsourced maintenance and operational management of the on-site generator.
The benefits of on-site gas generation are clear for many processing industries, not least flat glass manufacturers. However, there is a perception among some other industries that on-site gas generation can deter them from day-to-day work, has been a barrier to its development. Now new, high performance solutions are available, capable of meeting bespoke requirements, which can be installed on-site and managed on an outsourced basis.
Gavin Whitlock is with Generated Gases Group, Air Products, Walton-on-Thames, Surrey, UK. " target="_blank">www.airproducts.com/equipment"