Compressed Air Best Practices - September 2008 - (Page 57) Compressed Air Industry FOOD PACKAGING & PROCESSING | 09/08 | The basic operating data was: Production hours = 6,240 hrs/year Blended annual power rate = $.115 kWh Two single-stage vacuum generators at 6 cfm each full flow at 60 psig per palletizer for a total of 12 scfm each unit Air on/off time of total = (52 seconds on + 9.3 seconds off = 61.3 seconds) Annual operating hours air and suction on = 85% time x 6240 hrs = 5,304 hrs/year Average cfm = 52 seconds ÷ 60 seconds = 87% of full load flow = 5.2 scfm/ea valve open Or 10.4 scfm for two Annual Electrical Energy Operating Cost = 10.4 ÷ 4 each/scfm = 2.6 hp for each palletizer Or 2.6 hp x .746 ÷ 90 = 2.16 kW input energy 2.16 kW x $.115 kWh x 5,304 hrs/year = $1,318/year per unit Total for six units = $7,908 / year Our first suggestion to the plant was to change the software program so that the operating profile was on just the 15% of the time and off 85% of the time. Potential annual electrical energy savings = (2.16 kW x .115 kWh x 936 hrs = $233/yr) $1,085/yr each unit or $6,510/yr for six (6) units It was noted that this was only figuring the electric energy cost savings which “goes immediately to the bottom line.” No allowances for the other compressed air costs such as maintenance, repairs, depreciation, etc. The reply was immediate. “There is no way anyone is going to touch that software. This machine was made overseas and no one here is trained on it.” End of discussion. Our next suggestion had a little more bite. We suggested replacing the current Venturi vacuum generators with one vacuum generator integrated system with a built-in air economizing system. This product is a Venturi vacuum generator packaged with accessory components to automatically shut off the air supply when the target vacuum is reached and restarted as required (if required) to hold the vacuum. Complete automatic control is accomplished within the vacuum generator assembly and there is no requirement to modify or touch the host machines control software! Full integrated Venturi vacuum generator with automatic start/stop. Courtesy Parker.com www.airbestpractices.com 57 http://Parker.com http://www.airbestpractices.com
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