Compressed Air Best Practices - November 2008 - (Page 10) | 11–12/08 Focus Industry STEEL & METALS | CO2 O C onth of the M Air Audit d ompresse Intr Introduction This steel processing facility has been operating for more than 100 years. This facility is part of a la corporation with numerous plants around the world. This audit focused on the compressed large air system on one side of the Works, which we will call the “North Plant.” The North Plant operates from one central compressed air supply located in the Boiler House or Co Compressor Room. Air is fed from two 10" exit lines leaving the room, which both lead to a complete loop loo through all the various production areas. Over the last 25 to 30 years, the air supply came from three 7,000 scfm centrifugal air compressors (one Worthington and two Joy units). Back up and emergency air have lately been supplied by rental units. The primary compressed air dryers are four blower purge dryers — one rated for 10,000 scfm and the other three rated for 6,000 scfm. Over the last seven or eight years, the air demand in the North Plant has steadily grown by an average increase of 5,500 to 7,000 scfm with production levels generally staying constant. Earlier this year, the Worthington centrifugal suffered a major failure and the decision was made not to invest the money to repair it and consider upgrading the supply side equipment. After the failure of the Worthington unit, additional rentals were brought in until the replacement equipment was obtained. Plant management thought that before they upgraded the air supply to a new level, a study should be implemented to answer several questions: p Steel Processing r, Van Orme By Hank USA Air Power November/December Audit of the Month Where: Midwest USA Industry: Steel Processing Issues: Air Leaks, Inappropriate Uses and Blow-Off Air Audit Type: Supply and Demand Side Financial Summary Investment: $307,150 Energy Cost Before Investment: $1,515,000 Energy Cost After Investment: $660,000 Energy Savings/Year: $855,000 Simple Payback: 4–5 months Power Cost/kWh: $0.045 Operating Hours/Year: 7,008 What are the underlying causes of this continuing increase in compressed air demand? If this is wasted compressed air with no subsequent improvement in production or quality, what is the bottom line incremental energy cost to the Company? What action can be implemented to eliminate this air demand? What is the cost of the action? What is the return? p p Air Flow Reduction Before: Min/Max Air Flow: 13,000/20,000 scfm After: Min/Max Air Flow: 7,000/10,500 scfm Air Flow Reduction: 11,000 scfm Air Flow Reduction Projects — Savings Leak Management: 1,000 scfm Blow-Off: 3,800 scfm Air Horns: 4,700 scfm Diaphragm Pumps: 1,500 scfm Total: 11,000 scfm “A compressed air leak survey was conducted and 154 leaks were identified, tagged and logged.” 10 www.airbestpractices.com http://www.airbestpractices.com
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