Industrial Utility Efficiency    

Nitrogen Solutions for the Food Industry Generated on Location

Nitrogen, an inert gas comprising 79% of the atmosphere, can be distilled from ordinary air. However, companies that use this product in their everyday operations know that it’s not quite that simple and much more expensive than the stuff we breathe. The primary means of obtaining nitrogen for industrial use is to transport it onsite in liquid form, which must be shipped and stored at cryogenic temperatures. But, really, what’s the point of turning nitrogen into liquid for shipping, transporting it to where it’s used, and then turning it back into gas?

“This process requires energy to store the liquid at cryogenic temperatures (below 300 degrees), ship it, and warm it to a gaseous state,” said Tom Jeffers, President of Houston, Texas-based Generon Innovative Gas Systems (IGS) US. “Operating costs are crucial when evaluating system payback, and energy costs comprise the main portion of these. There are two technologies to separate nitrogen out of the air we breathe, pressure swing adsorption (PSA) and hollow membrane fibers. Generon IGS specializes in both technologies. PSA systems are more efficient for purities above 99% and hollow membrane fibers are most efficient at purities from 95% to 99%. Generon IGS is offering a solution to save time, space, and money generate the nitrogen onsite for easy and efficient use.”

 

The New Compact PSA System Nitrogen Generator

Nitrogen Generator  
The New Compact PSA System Nitrogen Generator
 
Controls Cabinet  
The Controls Cabinet of the Compact PSA System Nitrogen Generator
 
   
   

Generon IGS specializes in gas separation and compression solutions and offers various versions of nitrogen pressure swing adsorption (PSA) generators. The Compact PSA System bridges the gap between twin-tower PSAs used for high flow volumes (up to 120,000 SCFH at 95% purity) and modular, bank-type PSAs with expandable flows from 85 SCFH to 13,000 SCFH. The new Compact PSA Nitrogen Generator allows for multiple-bed PSAs to be installed on a common skid for purities from 95% to 99.9995%.

The new product design allows clients, requiring lower flows with high nitrogen purities (e.g., chemical labs, electronics industries), to utilize less space and reduces installation time. Air and nitrogen buffer tanks are integrated on a common skid, and patented piping and separation materials optimize the PSA process and pressure drop. “PSA technology has been around since the 1970s, but Generon specializes in packaging the technology for various applications,” said Jeffers.

 

How the PSA Process Works

The PSA process achieves continuous production of nitrogen through adsorption, regeneration and repressurization. During the adsorption phase, pressurized air from a compressor is forced into the bottom of one of the twin towers and through the bed of carbon molecular sieve (CMS). As this tower is pressurized, oxygen molecules are adsorbed onto the face of the CMS, and nitrogen molecules flow out the top. During the adsorption phase in the first tower, regeneration occurs in the second tower, depressurizing and releasing adsorbed oxygen through the vent line. The repressurization phase starts during the next cycle. The system offers input pressures up to 145 psig (10 barg), output pressures up to 120 psig (8.3 barg), flows up to 3300 SCFH (86.8 Nm3/hr), and purities from 95% up to 99.999%. “The PSA technology is better suited for applications that require nitrogen purities of 99% or higher”, said Jeffers. “The adsorption properties of the specially treated CMS permit efficient nitrogen production by charging two alternatively used adsorber vessels with compressed air,” said Jeffers. “While one vessel adsorbs, the other regenerates by pressure reduction. IGS has developed a proprietary mix of cycle timing and molecular sieve types to reach desired purity at maximum efficiency.”

 

Nitrogen Applications in the Food Industry

Use of nitrogen as a food preservative is gaining widespread acceptance as a non-chemical method of food preservation, as it can improve the quality and expand the availability of perishable commodities and leaves no chemical residues. In addition to preservation, compact nitrogen PSA generators have multiple applications in the food packaging industry, including packaging, fluffing, and head space replacement; controlled atmosphere storage and oxidation control of perishable foodstuffs; sparging of liquids/wines; blanketing of process operations to prevent combustion; beer dispensing; purging tanks and vessels; and pest control and fumigation.

 

Storage

Nitrogen does not react with elements around it and can be used to displace oxygen inside produce storage facilities, where it slows the ripening process. “Bananas are stored inside ISO containers for months before they ever reach your table,” said Jeffers. “Nitrogen slows down the ripening process and allows the fruit to remain viable during the transport process.” Generon’s nitrogen PSA generators are adjustable to achieve specified gas purity levels for various products; the ideal atmosphere for storage of vegetables and fruits is within the 95% to 99% purity range. The process also displaces the carbon dioxide produced by respiration of produce in storage space. Generon’s nitrogen-generating, hollow-fiber membrane technology also can create optimum atmospheric compositions for controlled atmosphere storage. Apples, bananas, kiwi, asparagus, blueberries, onions, and fresh cut flowers can be stored sometimes as long as one year.

 

Packaging

To prevent oxidation and spoilage of raw food ingredients, nitrogen is used inside food packaging to achieve a meaningful shelf-life extension. Almost every type of packaged food can thrive in a 99% pure nitrogen atmosphere, including chips, meat snacks, peanuts, and other snack foods which contain oxygen-sensitive oils. By using 99% gaseous nitrogen in the processing and packaging of coffee, the oxidation of flavorful oils is minimized, extending the shelf life and increasing profitability for the merchant and retailer. Food liquids can also benefit from the use of nitrogen. Purging the headspace between the liquid and the lid of bottles and containers and substituting with nitrogen can extend shelf life as much as 500%. Fruit juices may require 99.5% pure nitrogen, while many wineries use 99% pure nitrogen not only to purge the headspace but to purge the entire bottle before it is filled. Even bird seed is sometimes packaged with nitrogen.

 

Pest Control and Fumigation

In addition to its preservative qualities, nitrogen also has the capability to kill insects that eat grain. Nitrogen as a de-infestation chemical is gaining popularity as government regulators seek alternatives to ozone-depleting insecticides. Recent increases in sales of organic fruits, vegetables, and grains show that consumers also are becoming more aware of the dangers of chemical ingestion. “Farms are replacing air with nitrogen in silos to deter rodent infestation, and these types of uses of nitrogen are potentially a very large business,” said Jeffers. “We are still uncovering the many useful applications of nitrogen in various industries.”

 

Products by Generon IGS

Oxygen Generators: Generon’s Oxyswing® PSA generators, designed for heavy-duty operation, are available in twin-tower or modular-type models and can produce oxygen purities up to 99.9995% (with De-Oxo option), meeting a wide range of flows, purities, and pressures. The PSA process for oxygen generation mirrors that of nitrogen but utilizes CMS instead of zeolite (aluminosilicate material). For medical applications, the European Medical Device Directive 93/42/EC (equivalent to the FDA) has approved the Generon® Medical Oxygen PSA Generator. These also can be used as compact, turnkey portable field hospital units that can be configured on a single skid or installed in an ISO transport container.

Instrument Air Packages: Generon’s compact instrument air packages can be unitized with primary air compression to reduce size, installation cost, and time. Also available are standard twin tower desiccant dryer instrument air packages and standard or individualized skidded membrane instrument air packages. Standard systems are designed for non-hazardous applications and can be integrated with patented Generon® Nitrogen Membrane systems. Multiple communication software is available.

Gas Compression Packages: Generon IGS is an authorized packager for all the major gas compression manufacturers: primary compression (CompAir, Sullair, IR, GD, LeROI), and post-compression (Ariel, Hurricane, General Electric, Revell, LeROI). Systems are configured to custom specifications to meet all operating conditions and load capacities.

 

 

For more information please contact Generon Innovative Gas Systems, tel: 713-937-5200, www.igs-global.com.