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 Benefits of Case Index Developing an acceptable procedure to determine the system efficiency will have several benefits to the customer and the industry as a whole. p Compressed air system operators will have an accepted procedure to assess their system performance and compare it against others. System operators will have a tool for monitoring the system performance on a real time basis, and set trigger points for intervention. It will prevent drastic losses of efficiency due to control failures and other reasons. Such failures are commonplace for compressor systems. The CASE Index will provide a way to quantify energy savings from system improvements, and thus facilitate system improvement projects. It will lead to energy savings. This will provide an acceptable metric for energy efficiency program development and administration of rebate programs. System efficiencies will be quantified and benchmarked on many systems. It will lead to statistical graphs with mean, median, and such statistics, on compressed air central plants. This will facilitate monitoring of efficiencies for regulatory and governmental agencies at local, state, and federal levels. Figure 1. Test Bench p p p Inferential Mass Flow Meters p p 1. Orifice plate • Turn down ratio: 10 : 1 • Piping Modifications • System Shut down • Flow obstruction • Permanent Pressure Loss • Crud build-up 2. Venturi tube • Same as above 3. Pitot tube • Hot tap possible • Strict range limitations, Reynolds Number 200+ • Interference of particles, water droplets, etc. • Frequent cleaning and calibration 4. Magnetic Flow Meters • EMF proportional to fluid flow • Does not work for Compressed air due to Conductivity of air 5. Positive Displacement Flow Meters • Impeller, rotating discs, sliding vanes, turbine, etc. • Turn down ratio: 10:1 or may be 20:1 • Sensitive to contamination of bearings p Direct Mass Flow Meters 1. Constant Temp. TMF • Eldridge Products, Inc. • 2 Platinum RTDs • Turn Down Ratio: 1000:1 • Fast Response • Sensitive to Water droplets 2. Constant Power TMF • Turn down ratio: 100:1 • Three RTDs • Slow Response These benefits were well understood by the compressed air industry experts in Southern California from the outset. Their enthusiastic support to Southern California Edison Company by way of lending equipment, site selection, and technical advice, made this project a success. Project Steps Determination of CASE Index involves metering energy (kWh) flowing into and the compressed air (scfm) flowing out of the central plant. Metering kWh is routine, and does not involve complications. But metering compressed air flow is a different case. Reliability of flow data was recognized to be a major problem from the beginning. So the project was essentially divided into two parts: p Evaluation and assessment of accuracy of various compressed air flow measurement devices. p On site testing of selected metering systems and developing the CASE Index. Five test sites were completed so far. Evaluation and Assessment of Flow Metering Following is a brief summary of available flow meters and their reliability issues: 28 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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