Compressed Air Best Practices-August 2008

| 08/08 Focus Industry COMPRESSED AIR AUDITS | C O M P R E S S E D A I R S U P P LY E F F I C E N C Y equipments are also metered and recorded on the same time interval. All metering points are time synchronized to aid in the analysis and diagnosis of problems. The program calculates the index minute by minute, and prints it along with the scfm, and the total and individual kWh consumed. The CASE Index will vary between 0 and about 325. Higher numbers indicate better efficiencies. The average CASE Index for the entire week is calculated, and that becomes the efficiency statistic for the system. In the case presented above the compressors were rotary screw air compressors (75hp and 150hp). The two 75 hp compressors supported the plant, and the 150 hp was a stand-by for service. The maximum CASE Index potential for this system is around 293 (scf/kWh). The actual performance turned out to be 193. Considering the system set up with VSD compressor for trimming, the actual performance (CASE Index of 193), was way below that was expected. The results immediately indicated a need for a better sequencing control. In this case, the engineers in this plant set up a new controller with a PLC that operated based on the data coming from the flow meter. Compressed Air System Efficiency CASE Index — XXX Irvine Summary Of Results • Average CASE Index was 193 • CASE Index ranges was from 58 to 286 • This was the result of a one week study — 2/12/03 to 2/19/03 • CASE Index measures the overall efficiency of the compressed air system. Higher number indicates higher efficiency. Improvement of 10 units in CASE Index is equal to saving 35,000 hWh a year for this installation. Two strategies to improve the Index without much capital investment: 1. Shut down the Base Compressor from 1.15 A.M. to 4.45 A.M. Estimated new CASE Index: 210 17 Index points improvement — 59,500 hWh/Year savings 2. Use the flow meter to shut down Base Compressor at 220 scfm and restart at 280 scfm. Estimated new CASE Index: 228 35 Index points improvement — 122,500 kWh/Year savings XXX Irvine could install a 100 hp compressor with VSD. This would be sufficient to supply the plant 24 hours a day, and will improve the CASE Index even higher. Results Results from the five on site tests are summarized below. Table 1. Summary of On Site Test Results SITE # HP CASE INDEX CASE IND (MAX) REMARKS 1 2 3 4 5 75 30+30+15 300 150+75+75 650 4x125+150 600 4x150 130 2x40+2x25 128 193 215 243 241 300 293 300 312 286 Many improvement opportunities. Financially not justifiable due to small system size New controller for sequencing. 122,500 kWh annually Suspected solenoid malfunction. Being traced. Energy impact unknown. Replace QSI490 with 150 HP VSD compressor. 617,000 kWh annually. Replace all four with 100 HP VSD unit. 88,000 kWh annually Figure 5. Summary of Report efficiencies for various plants within the corporation. In the studies presented above, site #2 and #5 belong to the same corporation. After the first study, engineers for this corporation recognized this as a benchmarking tool, and are now involved in studying the compressor systems in several plants. Utilities and regulatory agencies could quantify system efficiencies and develop statistical histograms for a geographical area and track progress of energy efficiency efforts. If the histogram in 2005 yields an average CASE Index of 200, and a similar curve yields 220 in year 2010, the progress in the five year period can be claimed to be 20 CASE Index points or 10% for the area. Typical Report The study issues a final report on the system performance with a Summary Section and the Data File. The Data File contains about 12,000 individual lines of data. The Summary Section and a brief portion of the Data File for one of the sites are below. Future Studies This is a very useful tool for benchmarking compressor system efficiencies. Many companies have multiple plants, and would want to have a benchmarking tool to document, compare and track system 30 www.airbestpractices.com http://www.airbestpractices.com

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

Compressed Air Best Practices- August 2008 Contents From the Editor Utility-Air News The August Audit of the Month: A Vacuum System Audit Energized for Savings at Seattle City Light and Tacoma Power Know Your System CASE: Compressed Air Supply Efficiency Ecos Air: Managing Incentive Programs Kaeser Compressors: Loyalty, Energy and Growth Building Relationships at Cummins-Wagner McIntire is Moving Forward The 2008 A.I.C.D. Conference & Exhibition Tuthill Vacuum and Blower Systems Resources for Energy Engineers: Training Calendar & Product Picks Wall Street Watch Advertiser Index Job Market

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