Advances in Gas Membrane Products and Processes for Commercial N2 Generation

Generon is a supplier of state-of-the-art air separation membrane technology. While this technology has been commercially available since the early 1980's, new more efficient membranes and modules have improved the economics of membrane generated enriched N2 to make it the technology of choice for onsite generation of N2 for many applications.

(PRWEB) October 30, 2006 -- Generon is a supplier of state-of-the-art air separation membrane technology. While this technology has been commercially available since the early 1980s, new more efficient membranes and modules have improved the economics of membrane generated enriched N2 to make it the technology of choice for on-site generation of N2 for many applications. Over the last few years, this technology has been widely applied in several industry sectors for the on-site production of moderate to high purity N2. Features of the technology such as its portability, simple operation, proven reliability, minimal space requirements and low cost have made it the preferred technology for many major applications.

For the purposes of this report, we focused on applications in the food processing, metal manufacturing and fabrication as well as the electronics industry. Combined these industries comprise 35 to 40% of the worldwide N2 use. This amounts to over 400 BCF (10.5 BM3) of N2/year for the United States alone (estimate from The Freedonia Group, Inc. circa 1993). Over the past 15 years Generon has been a major force in supplying these industry segments.

Typical Membrane Based N2 Generator System
The typical membrane system for delivered N2 can be broken down into 2 parts. The first part is the compression and feed air pretreatment system. The compressor is sized based on the feed air requirements of the modules to deliver the required product flow, purity and pressure. An air pretreatment system is then designed to match the compressor airflow rates. The pretreatment system is critical to the durability of the modules and system. It must remove all liquids (both water and oil) from the feed gas. Particulate must also be removed to avoid fouling of the modules. Typically liquid water is removed via moisture separators, although membrane driers and the superheating of the feed air are often used as an alternative. Two coalescers, a coarse and a fine, are used along with a carbon tower to remove any heavy organic in the feed stream. A process heater is used prior to the modules to control the operating temperature of the modules since the separating capacity and efficiency of the modules are temperature sensitive. The second part of the typical system involves the module themselves. The conditioned feed air is manifolded to feed an array of modules. A flow control valve or backpressure regulator placed at the discharge end of the module(s) controls N2 product flow and purity. Many systems allow for the constant monitoring of feed pressure, N2 purity and product flows.

Applications in the Food Industry
Membrane produced N2 has been an important factor in the food industry as a cost-effective method of improving the quality and storage life of several foodstuffs. Significant research over the last decade or 2 has lead to a wealth of information in the area of controlled atmospheres for food storage. Typically these controlled atmosphere studies have centered on the impact of CO2, ethylene, O2 and temperature on the storage life of various foods. Based on these studies, one can set up controlled atmosphere systems optimized for different food types. Interestingly, the ideal O2 content is rarely if ever 0%, some O2 is typically required to maintain the foods integrity while in storage. Membrane produced N2 is ideal for such systems since it can be operated to deliver from 90 to 99+% N2 for different foods very simply and shows good economics for the 97-98% N2 purities often desired.

Generon has provided membrane systems for stationary food storage and packaging as well as for shipboard and truck mounted controlled atmosphere systems. In these latter applications, the compact size, low maintenance and low weight of the membrane product has been an important factor. We have contributed in systems used to store apples, bananas, onions, grains, nuts, dairy products, coffee, wine, beer, etc. Some systems are dedicated to preserving a certain food product while others are used for a number of different perishables.

High Purity Application in Metal Cutting / Electronics Industry
A good example of how far membrane technology has come for the production of N2 is a recent application in which high purity N2 is used to inert laser cutting of metals. To prevent oxidation, the O2 content must be less than 0.1% O2 and ideally less than 0.01% O2. Five years ago this degree of purity was not economically possible with membrane technology. Now we can design and operate multimodule systems to deliver this purity without difficulty. Improvements in module performance, system cost and skid designs have allowed this application to become practical. This new system can operate at 99.99% N2 with 20% greater productivity and 30% lower feed air requirements than previous membrane based systems. Trials on this systems proved successful in cutting steel at thicknesses over 1".

Similar purities are required in wave soldering and in reflow ovens used in the electronics industry. This high purity often makes cryogenically produced N2 the preferred choice because of cost but we have placed systems into this application over the past few years. The economics for these applications were attractive because the manufacturing sites did not have easy access to cryogenically produced N2.

Conclusions
There are several applications within the food, metal fabrication and electronics industries that have benefited from the use of membrane technology to produce N2 gas. Membrane based systems can produce a wide range of N2 purities and pressures and are easily customized to meet the requirements of a particular application. Membrane systems are also compact, lightweight and portable. The membrane modules have no moving parts to fail and given adequate pre-treatment can last for many years of continuous use.

We at Generon have been at the forefront of air separation membrane technology for over 20 years. We are providing to the market both custom module types and module systems for use in a wide array of industrial applications.

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