Plant Services - April 2008 - (Page 48)

Take these steps to ensure you approach the lowest life cycle cost W ith energy cost rising at 7.5% per annum, maintenance professionals seek the best return on investment and drive costs down. Compressed air is an area where improvements are readily available. Compared to lighting, chilled water, steam and HVAC, there’s limited knowledge of energy conservation in this venue. Plants have a “keep it running” mind-set and maintenance supports it at any cost because of fear that ﬂourishes in the absence of knowledge. Most production departments aren’t accountable for the cost of air or the consequences of their actions. At 7 cents per kWh, producing 100 scfm at 90 psig for one year costs more than $13,750 in electricity. But most plants allow production to add to air consumption freely and evaluate equipment on the basis of initial cost with little interest in life cycle cost. Most air systems are conﬁgured to handle the peak usage with no consideration given to diversity or transient event management. Air system waste can exceed 30% of the total. Even in a small system, leakage can be 200 scfm. Because it’s a no-see-um, it goes unnoticed. at 200 scfm is equivalent to 1,496 gpm. If it were a water leak, you couldn’t ignore it (Figure 1). audit focused on the compressor can miss the root causes of energy waste and operating cost. Many consultants offer air system audits, but most don’t evaluate the constituents of demand or determine the root cause of any system problems uncovered. Focus on audit team capabilities. You want the entire system analyzed, including demand constituents and critical pressures. Use auditors who have examined systems similar to yours, designed the implementation, demonstrated a positive ROI and delivered the results. Deliverables should include a thorough ﬁ nancial evaluation. Auditors should understand air and your system’s demand side. Review a few of their reports and call the clients for feedback. Be up on the basics Do the detective work Without quantifying the constituents of demand, you’re missing from 35% to 50% of any reduction opportunity. An 48 An air system has ﬁve functions. It must: • Compress the air as eﬃciently as possible. • Flatline usage and control system rate of change. • Distribute the compressed air eﬃciently. • Expand the air to take advantage of the energy. • Have users applied, installed and operated correctly. e audit team must evaluate these functions to achieve a reasonable solution and ROI, but most don’t examine signal locations, the eﬀect of diﬀerentials, supply system A .PLANTSERVICES. http://www.PLANTSERVICES.com

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Plant Services - April 2008

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