Compressed Air Best Practices-August 2008

| 08/08 Focus Industry COMPRESSED AIR AUDITS | KNOW YOUR SYSTEM While the CASE Index uses SCF (standard cubic feet) per kWh (kilowatt hour), Manitoba Hydro decided to use kW per 100 cfm as an index for efficiency monitoring. This is the same index used by the Compressed Air and Gas Institute (CAGI) for measuring air compressor and dryer efficiencies. The CAGI specifications for a wide range of new compressors and dryers are readily available on the websites of most suppliers. It was felt that this index would be simpler to use as unit of comparison and would be easier to compare with this published CAGI data. We have had good success with four permanent experimental installations to date with two more nearing the commissioning phase. This type of installation is very useful in our measurement and verification efforts for very large efficiency projects and goes a long way to ensure the sustainability of the savings in these systems. kW Results from the Field Some interesting examples of the results of our using flow and power to assess systems: • A bakery using modulation compressors installed a flow meter to determine system flow. After data logging, the system was determined to be operating at a level of 50 kW/100 cfm. The compressors are rated at 18 kW/100 cfm at the current system pressure. The site did not previously monitor power or flow. CO2 O • A large mine in northern Manitoba was running a 7,000 cfm 1,750 hp compressor in blow-off mode. Flow meter readings showed the mine flow was actually consuming 3,000 cfm, yet data logging showed compressor was drawing near full load power. The excess air was being blown off to atmosphere. Compressor power consumption was about 12,000,000 kWh per year. Specific power for this system was 46 kW/100 cfm. The system was replaced by four large screw compressors with sequencing control with a 7,000,000 kWh per year reduction in energy consumption resulting in a $190,000 per year savings. Site previously measured flow but not power. • A large aerospace facility is using two large 350 hp centrifugal compressors running in modulation. Flow meter readings showed the actual average plant flow was 795 cfm. The excess was being blown off to atmosphere. Compressed air power consumption was about 4,855,000 kWh costing $189,400 per year. Average specific power for this system is 70 kW/100 cfm. Site does not measure flow or power. An efficiency project is pending. • A large hospital was using one large 175 hp centrifugal running in modulation. Site flow meter readings showed the actual average flow was 205 cfm. The excess was being recycled to the inlet of the compressor. Compressed air power consumption was about 1,328,000 kWh costing $64,000 per year. Specific power for this system is 74 kW/100 cfm. The site previously measured flow but did not monitor power. A VSD compressor was installed and saved 56% or $37,000 per year. 26 www.airbestpractices.com Conclusions Air system monitoring is very important as an awareness and enabling tool for system users. Our experience suggests flow metering is a very important part in providing accurate system monitoring, which directly leads to higher quality options for system improvements and greater confidence in the potential project results. It should also be emphasized that flow metering is meant to compliment amp, power and pressure readings, not replace them. The advent of low cost flow metering and affordable and flexible power metering is making this type of monitoring more economical for permanent installations. The use of this data is often very revealing, and an eye opening experience for system owners and operators. In our experience the key to successfully optimizing your system begins with knowing your system. For more information, please contact Ron Marshall, CET, CIM, Certified Energy Manager, Industrial Systems Officer, Manitoba Hydro, tel: 204-474-3658, email: rcmarshall@hydro.mb.ca, www.hydro.mb.ca http://www.hydro.mb.ca 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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