Compressed Air Best Practices - March 2009 - (Page 16)

® | 03/09 Focus Industry ENERGY MANAGEMENT | COMPRESSED AIR AUDIT OF THE MONTH A Steel Cord Producer Manages Pressure Supply-Side Recommendations The compressed air supply, utilizing sufficient storage and proper distribution, must meet the compressed air demand. If supply, storage and distribution are not in tune or aligned, excessive pressure fluctuations will occur resulting in increased operating costs. Most compressors’ ability to load or unload is controlled by line pressure. Typically, a drop in pressure indicates an increase in demand. This then causes a compressor to come on-line or load and thus handle the increase in flow. In this system, this takes place on a regular basis as pressure rises and falls; however, the compressors cannot see the true production floor pressure and are only reacting to the pressure in the wet receiver. The wet receiver, as we have seen from our data, could be 10–15 psig higher than actual point-of-use pressures. There is no automation in place to orchestrate the compressors starting or stopping. Because it is very difficult to successfully cascade more than two compressors, there are times when the system is running with too much horsepower, all sharing the load and they simply cannot react to demand events in time. With no automation, compressors maintained a higher than normal power usage regardless of production requirements. This occurs because as the pressure increases, so does the demand for air in all unregulated uses such as leaks, open blowing and users with the regulators cranked all the way open. This phenomenon is called “artificial demand” and it prevents the compressors from being able to equalize the pressure throughout the header. Electric-Timed Drains Electric-timed condensate drains are used on each compressor and on each receiver tank. A 1⁄4-inch timed drain operating for 10 seconds and open every 30 minutes (at $0.05kWh) can cost $700 in compressed air loss per year. The system has six in operation, which potentially is costing over $4,000 in compressed air. Ask your vendor for zero air-loss type drains, and replace the existing drains. Conclusion The audit of this facility has discovered the source of the pressure fluctuations and recommends examining alternatives to the pumps being used that cause these demand events. We also recommend the installation of a new 3-inch header down through FP starting at the dry receiver. This header should be tied into the existing loops. Purchase a fixed-speed compressor rated at 100hp that will enable a reduced energy profile to operate under the current and future demand environment. Finally, perform a thorough leak check, especially on the under floor trough piping and replace timed condensate drains with zero air loss type condensate drains. AVG. AIR FLOW, ACFM AVG. AIR FLOW, %CS. PEAK DEMAND kW LOAD FACTOR, % ANNUAL ENERGY, kWh ANNUAL ENERGY COST, $ COMPRESSOR New Compressor If we were to install a 100-hp air compressor, such as a GA75 lubricantinjected fixed speed, we can accomplish what the rental and the ZT45 are currently doing but with less power. A single 100-hp compressor would require about 82kW fully loaded and output 460–480 cfm. Now we only need to trim with the GA55VSD. This puts all lubricant-injected rotaries online, which have a greater cfm per bhp than oil-free. This equates to a $14,184 savings over the existing baseline. System Baseline New System Total 586 536 39.6 36.2 148.9 101.4 45.3 30.3 1,251,292 835,544 56,871 37,975 For more information please contact Donald Wirth, Tencarva Machinery Co., tel: 615-742-3101, email: dwirth@tencarva.com, www.tencarva.com 16 www.airbestpractices.com http://www.tencarva.com http://www.airbestpractices.com

Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - March 2009

Compressed Air Best Practices - March 2009 Contents From the Editor Utility-Air News Compressed Air Audit of the Month Air Standards Assessment Improves Electroplater Production and Saves Energy Demand-Side System Optimization Seven Sustainability Projects for Industrial Energy Savings Personal Productivity Resources for Energy Engineers Wall Street Watch Advertiser Index Classifieds

Compressed Air Best Practices - March 2009

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