Compressed Air Best Practices - March 2008 - (Page 13)

Focus Industry FOOD PROCESSING | 03/08 | To gain the necessary data to evaluate the air usage, we took a look at their historical recorded flow data gathered from a common mass flow meter at the discharge of three blowers. After plotting the amps and pressure trend data on the existing blowers, we discovered there was an error in the recorded flow measurement due to the placement of the existing mass flow meter. The flow meter was placed in a turbulent part of the main discharge header and, being an insertion type mass flow meter, did not give accurate readings. Instead we relied on plotting the recorded amp usage and discharge pressure to determine the actual flow used over time using the existing blower curves. This took quite a bit of work, but the conclusion was that the total flow produced far exceeded anyone’s expectations. With this base line process data, the HSI team went to work on a proposal to improve both the efficiency and reliability of this low-pressure system. The Proposal Focuses on VFD Blower Controls The audit recommendations focused on the tremendous variations in flow. The proposal suggested that the three existing blowers be replaced with three new centrifugal blowers equipped with variable frequency drives, which could deliver energy savings during the partial load conditions. Under base-load conditions, the new centrifugal blower designs also offered improved mechanical efficiencies due to modern impeller and casing designs using today’s latest Computational Fluid Dynamic programming. The new system was designed to meet continuous flow and pressure range from 8,000 scfm to 66,000 scfm without any gap or interruption in flow — eliminating the need for blow-off control. Using a local control panel and operating with a variable frequency drive, the new blowers offered a greater turndown range (65% reduction from maximum flow) than any conventional throttle-valve control. Each proposed blower could operate from 8,000 scfm to 22,000 scfm. The expected efficiency gain (offered in the audit recommendations) over the installed system was to save 6,204,000 kWh per year — the equivalent of 831 hp running on a continuous basis under these operating conditions. www.airbestpractices.com 13 http://www.coaire.com http://www.coaire.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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