Compressed Air Best Practices - March 2008 - (Page 18)

| 03/08 Focus Industry FOOD PROCESSING | Managing BY JIM TIMMERSMAN Air Compressors kW Rotary Screw at Midwest Bakery CO2 O Financial Summary Investment $64,141 Energy Cost Before Investment $198,686 Energy Cost After Investment $120,014 Energy Savings/Year $78,672 Input kW Before Investment 500 kW Input kW After Investment 302 kW Power Cost/kWh $0.045 Operating Hours/Year 8760 Project Life (Years) 10 Power Cost Escalation/Year 2% Power Supply Industries was contacted by Midwest Bakery’s corporate engineering office informing us that the plant was about to expand and that the engineering manager wanted to purchase an air compressor for the expansion. The corporate engineering contact was aware of our previous successes auditing the food industry and asked for a detailed audit to assess the situation and determine the proper size of the new compressor or, at our request, determine if one was needed at all. The plant estimated that a 150–300 hp air compressor would be needed and was looking for guidance on the correct size air compressor to install. The audit Power Supply Industries performed was very detailed, including measurement of power (kW), air flow (scfm), pressure dewpoint (F) and pressure (psig). This detailed analysis of the supply side of the system was important in determining the current demand. All three measurements were recorded every second to show percentage of time at various loads and power required for each load period. This information helped to calculate the dynamic efficiency rating of the compressed air system, determined by measuring the scfm delivered per kilowatt. The bakery’s rating of 3.57 CF(cubic feet)/ kW left much room for improvement by simply managing the compressed air system. Managing the air system involved: 1. 2. 3. Sequencing the air compressors Controlling the compressed air system to the lowest allowable pressure Adding 10,000 gallons of storage for peaks in demand. 10-Year Summary Energy Savings Before Tax $797,295 Payback Period Before Tax (Years) 0.82 Energy Savings After Tax $414,594 Internal Rate of Return After Tax 70% These improvements enabled us to increase the dynamic efficiency rating to 5.58 CF/kW. Implementing compressed air management allowed the plant to avoid the purchase price and annual energy cost of a new compressor, resulting in an annual energy savings of $35,411. The supply side energy savings totaled $114,083 with very little capital investment and a less than 10-month simple return on investment. 18 www.airbestpractices.com http://www.airbestpractices.com

Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - March 2008

Compressed Air Best Practices - March 2008 Contents From the Editor Utility-Air News The Compressed Air Audit of the Month: Saving Energy with Blowers in Canada Do You Provide World-Class Service? Managing Rotary Screw Air Compressors at Midwest Bakery The Difference Between Acfm and Scfm for Proper Vacuum Sizing Best Practices — Multi-Module Process Air Dryers The Vacuum Formation Process in Building Compressed Air Filter Elements Solberg Manufacturing Real World Best Practices: Measuring Pressure Dewpoint in a Compressed Air System Resources for Energy Engineers: Training Calendar & Product Picks Wall Street Watch Advertiser Index Job Market

Compressed Air Best Practices - March 2008

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