Compressed Air Best Practices - January 2008 - (Page 11)

Focus Industry ENERGY MANAGEMENT | 01/08 | Significant Savings Are Available when Applied Correctly Below is a plant case study. The graph reflects two performance curves at a vinyl extrusion plant in Washington State. The upper curve reflects the kW power draw of a 75 HP class constaint-speed, inlet-valve modulation controlled single-stage, lubricant cooled rotary screw compressor (avg. 57.66 kW). The lower curve is the kW draw of a 75 HP class, variable-speed driven, single-stage, lubricant cooled rotary screw compressor (23.54 avg kW). Both units ran at the same demand profile. In this application there is a 40.8% reduction in power draw. The 34.12 kW reduction at $.07 per kWh generates $20,922 per year in electrical energy savings (these measurements were taken by plant personnel). The average flow is about 175 cfm at 100 psig with peaks to 210 cfm. The demand profile is about 50 to 60% load. The savings are significant. Why Did This Application Work? Referring back to the performance curves in Figure 1, when the VSD is compared to an inlet valve modulation constant-speed compressor, the VSD becomes more power efficient from 85 to 90% flow demand (varies with the actual slope of a specific compressors performance curve). We are in the “sweet spot” for the VSD which in this case can operate more and more efficiently right down to 10% flow demand at which point it can then shut off if desired. If the flow demand were from 300 to 350 cfm on a continuing basis these would be little or no savings. Variable speed drives should not run significant hours per year at higher loads. They are effective “trim” units, not base load. Most plants will only need one appropriately sized variable speed driven unit as a trim compressor. CP Compressors 1800 Overview Drive Rock Hill, SC 29730 support@cpcompressor.com CP Compressors Canada 125 McBrine Place #2 Kitchener, Ontario, N2R 1G4 Distributor Opportunities Available 1-800-528-5192 www.airbestpractices.com 11 http://www.airbestpractices.com

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

Compressed Air Best Practices - January 2008 Contents Focus Industry Features Compressed Air Industry Articles From the Editor Real World Best Practices: Selecting A VSD Rotary Compressor Audit of the Month: Energy Savings in Peru The Low-Hanging Fruit in Pneumatic Systems Mikropor America, Inc. Wireless Sensor Networks: Improve Efficiency in Compressed Air Systems Special Report: The Chicago Pneumatic Compressor Launch in North America The Importance of Measuring Vacuum The Comp-Air Service Co. Special Report: The 2007 NAACD Wall Street Watch Advertiser Index Job Market

Compressed Air Best Practices - January 2008

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