Compressed Air Best Practices - April 2008 - (Page 30)

| 04/08 Focus Industry PLASTICS BLOW-MOLDING | GUARANTEEING AUDIT ROI FOR BLOW-MOLDERS 3. Measurement Method and Location: We precisely measure how much storage there is in the piping, storage tanks and all other parts of the system. We use pressure loggers to measure pressure in the headers and general system pressure. For high-speed loggers, we use pressure transducers where we can vary the speed and still provide output data. These pressure transducers will take 25 measurements a second — for a whole hour. a. We usually measure at the exit of the compressor rooms’ main header pipe so we can see what pressure is coming out of the compressor room and their start/stop behavior CO2 O The Three Steps for ROI Guarantees Step 1: Analysis and Quantification of Savings and Costs Step 2: Execute the Project and Verify the ROI Step 3: Maintain the Gain and Monitor ROI kW b. The signal location within the compressor is another measurement location. This allows us to look at the behavior of an individual compressor behavior in start/stop mode. Customers are often amazed to learn that their air compressors are ramping up because of a leak in the small solenoid drain valves placed on the after cooler separators of the air compressors c. Measure pressure change on production equipment. Pneumatic systems are often undersized or have failed pressure regulators. Pneumatic circuit tubing can also cause changes in pressure Analysis of Costs in a Project This analysis must look at the costs required to improve the compressed air system and to modify production equipment. When improving the compressed air system, we are usually reconfiguring and controlling the system better — rather than buying new equipment. In blowmolding installations, we normally see equipment costs, which will include additional air storage, automation systems to control multiple air compressors and variable speed drive (VSD) air compressors to more efficiently manage the variations in demand. New air compressors are required only 15–20% of the time and are normally related to production expansions. Production area costs lie in the process equipment, which has been improperly designed (for the existing working conditions) from the pneumatic system standpoint. Injection and extrusion blow-molders are often sped up to 50% greater speeds than the pneumatic systems were designed for. The blow-molding machines often are blowing bottles two to three times bigger than the pneumatic circuits were designed for. This causes both pressure drops and air quality problems within the process equipment. In PET Stretch Blow equipment, we see pressure changes from 60–70 psig all the time. We’ve seen equipment, which should be at 600 psi, experience changes that take it to 500 psig. Pressure restrictions of four to five bar (57 to 72 psig) are very common. Air consumption goes up and the pneumatic circuits simply can’t handle it. The facility is then forced to increase overall air system pressure to make up for it. 30 www.airbestpractices.com http://www.airbestpractices.com

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Compressed Air Best Practices - April 2008 Contents From the Editor Utility-Air News The Compressed Air Audit of the Month: Minimizing Blow-Molding Pressure Fluctuations AF Compressors: Focused on 40 Bar, Oil-Free Air for the PET Industry Real World Best Practices: PET Plants Using Boosters for High-Pressure Air Guaranteeing Audit ROI for Blow-Molders Managing Vacuum Pressure Differential Are You Taking Full Advantage of Pneumatic Valve Technology? Are You Strategic? Resources for Energy Engineers: Training Calendar & Product Picks Wall Street Watch Advertiser Index Job Market

Compressed Air Best Practices - April 2008

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