Compressed Air Best Practices - January 2009 - (Page 11)

Focus Industry ENERGY REBATES | 01/09 | Old System Inefficient Many years ago Boeing had installed an on-site nitrogen generator to provide lower cost gas than could be provided by trucked-in liquid nitrogen service. This system used a 250 horsepower (hp) two-stage high-pressure screw air compressor to feed a membrane-style nitrogen generator. The generator separated the high-pressure air into two streams; one of waste gases vented to atmosphere, the other a flow of high purity nitrogen that was directed to the plant nitrogen system. Boeing’s plant nitrogen demand is normally very low, but has huge peaks when the autoclaves are pressurized. This required the compressor to operate at very high pressures to keep as much nitrogen in system storage tanks as possible. Due to this high-pressure requirement, the compressor operated using the inlet modulation control mode, greatly reducing its efficiency when low nitrogen demands occurred. The compressor and nitrogen generator was also installed outdoors and consequently had to be run 24 hours a day and 7 days a week during cold Canadian winters to keep from freezing up. Over the years the original system had aged and was experiencing maintenance problems and reduced capacity. This increased the quantity of expensive liquid nitrogen that had to be used to supplement the old nitrogen system. The cost of liquid nitrogen is substantial — up to 38 times the cost of producing the gas onsite. As a result, this rising liquid nitrogen consumption had the production manager’s attention. The Boeing nitrogen project qualified for an $84,500 Incentive from Manitoba Hydro. Huge Peak Flows The Boeing autoclaves are more than just simple curing ovens; these mammoth pressure vessels are big enough to accommodate very large aircraft parts. The largest unit is 50-feet long with a diameter of 16 feet, big enough to swallow a large transport truck. The volume of the largest of these vessels is just over 10,000 cubic feet. To maintain adequate production output levels, the operating procedures require these vessels be filled to pressures as high as 100 psi in as little as 20 minutes. This equates to peak Nitrogen flows of 3,450 cubic feet per minute, much less than the existing nitrogen generator capacity. 11 http://www.mikroporamerica.com http://www.mikroporamerica.com

Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - January 2009

Compressed Air Best Practices - January 2009 Contents From the Editor Utility-Air News Compressed Air Audit of the Month: A Nitrogen Audit at Boeing Air Standards: New ASME & ISO Standards for Compressed Air System Assessments Energy Rebates Assist Industrial Sustainability Initiatives Seven Sustainability Projects for Industrial Energy Savings: Project #1: Lighting Optimization Minimum Supply Wire Size Recommendations for Compressor Packages Utilizing Variable Frequency Drives The Pneumatic Advantage: Pneumatics Bring Precision and Reliability to Furniture Industry Specialist Personal Productivity: Is Afternoon Fatigue Influencing Your Job Performance? The Explanation and Some Solutions. Resources for Energy Engineers: Training Calendar & Product Picks Wall Street Watch Advertiser Index Classifieds

Compressed Air Best Practices - January 2009

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