Industrial Utility Efficiency    

Leaks

So you’ve purchased an ultrasonic leak detector after a sales person gave you a demonstration on detecting compressed air leaks. You’ve read all those articles on how air leaks are wasteful, expensive and leakage programs provide good paybacks. Perhaps you’ve even had a go at a leakage survey. Either way, by now you’ve realised leakage programs are not as simple as they sound and without an ongoing plan of attack, you will probably never see the results you thought you could achieve. This article is written to illuminate common mistakes made in leak surveys and hopes to provide guidance on how to turn that around.
Employees of New Gold’s New Afton Copper/Silver/Gold Mine, located just West of Kamloops, British Columbia, Canada have just completed an intensive round of Compressed Air Challenge and in-house compressed air efficiency training for their employees. The awareness raised by these seminars has already led to significant improvements to system efficiency. Further efforts initiated by Andrew Cooper, an Energy Specialist hired through special support from BC Hydro’s Power Smart program are set to gain even more power savings and improve their compressed air system reliability and stability.
The purpose of the audit is to improve reliability throughout the facility. Reliability on the demand side can be defined by having adequate air pressure and air quality at all times throughout the facility. This outcome is a function of both the operation of the supply side in the operation of the demand side. If a demand problem occurs, such as a dust collector pulsejet failure, it can reduce the air pressure in a local sector. If a compressor fails, any backup compressor takes too long to start, the pressure would drop in this circumstance too
This food industry factory, located in California, was spending $386,533 annually on energy to operate their compressed air system. This system assessment detailed eleven (11) project areas where yearly energy savings totaling $154,372 could be found with a investment of $289,540. A local utility energy incentive, paying 9 cents/kWh, provided the factory with an incentive award of $159,778. This reduced the investment to $129,762 and provided a simple ROI of ten months on the project.
Why are compressed air leak programs often ignored or even discouraged by management, in addition to some energy recovery minded third parties? This problem can be summed up as “Over Promise” and “Lack of Delivery”. In the 1990’s, the basic compressed air inefficiency energy transfer became a prime target for energy reduction programs promising great results with many low investments. Good payback programs, which they are indeed.
Years ago, while managing the service department of my compressor distributorship, I received a call from a nearby customer who told me his 200hp compressor wouldn’t make any air. When I arrived at the plant I found the inlet air filter differential indicator showing “Red”, which indicates the filter element was dirty. When I pointed this out the maintenance manager said he had just changed the filter element; however, when I removed the element the compressor immediately started making air. He then admitted that the element was one that they had simply washed out approximately seven times before. Unwittingly, when he tried to save money by cleaning the filter element he was increasing his energy cost several times more than the cost of the element.
Why So Many Air Leaks - Even Today?! Energy conservation has been much talked about lately, in the media, the government, and at the water cooler. Lean manufacturing is also a popular topic these days, as are any ways to increase productivity, reduce costs, and increase profitability.  
“Instead of adding supply equipment, we fix air leaks and incorporate high-efficiency air nozzles, blower packages and point-of-use receivers.” These demand-side actions stabilize compressed air system pressure and this ultimately increases production output, reduces production down-time and spoilage costs, and decreases the power costs of the compressed air system.
This Midwestern prepared food company now spends $269,463 annually on energy to operate their compressed air system. This figure will increase as electric rates are raised from their current average of 6.2 cents per kWh. The set of projects recommended below will reduce these energy costs by $112,902 or 41%. In addition, these projects will enhance productivity and quality and reduce equipment maintenance costs. Estimated costs for completing the projects total $146,102, which represents a simple payback of 15.6 months.
Understanding the supply side of the system is important, but more important is first looking at compressed air demand. One demand that is consistently in need of attention in industrial facilities is the air flow caused by leaks.
The secret to success is to understand the nature of what type of leak produces a detectible ultrasound and what does not, along with the techniques that can be used for effective leak identification.