This article reviews portions of an audit report commissioned to survey the condition of a compressed air system in a factory located in the U.S. The objective of this study is to determine the current operating conditions and make recommendations for improvement based upon application of industry recognized best practices. Due to article space limitations, this article will focus on portions of the over-all audit report provided to the factory.
Compressed air has moved to higher visibility in the energy conservation field, and the buzzwords abound: “the fourth utility” — “your most expensive utility” — “eight times more expensive than electricity” — “a quarter-inch leak costs $9,000 in wasted energy.” This greater awareness has also produced compressed air auditors that are springing up like summer dandelions. With audits available from many sources, it is important to understand what plant operations, engineers and maintenance managers should expect from a complete audit — or more aptly — a complete air system review.
As a reader of this journal, you are well aware that large compressed air systems often have significant wasted air — often from leaks — that represent tens of thousands of dollars of waste per year. However, it is our experience that the so-called “low-cost” measures identified often go un-repaired, while other more costly capital projects get funded. Why? With an ROI of a half year or less, they seem like IQ tests to many compressed air auditors.
As plant personnel know, repairing compressed air leaks can be an expensive, labor intensive and never-ending process. This article discusses ways plant personnel can reduce and maintain their leak rate at a lower level without repairing leaks. It discusses how pressure/flow controllers, variable speed and variable displacement compressors, automation, and addressing critical plant pressures allow plant personnel to lower the header pressure, which eliminates artificial demand and controls the leak rate. More importantly, the article brings a new dimension to the idea of turning off the air to idle equipment by focusing plant personnel’s attention on the idle time within the cycle of operating equipment.
Over many years of reviewing industrial compressed air production machinery, of many types and styles, there is one common thread or complaint; “push-to-connect pneumatic tubing connections/fittings are a continual source of compressed air leaks and production interruptions.” Probably seventy-five to eighty percent of push-to-connect type tubing fittings use flexible tubing selected for lower material cost and assembly rather than an alternate appropriate hard metallic tubing.
How does one become a top notch compressed air auditor? There is very little in the way of formal schooling available to help interested persons become competent in the art of assessing compressed air systems or recommending improvement measures. As we will read in the following interview, having an excellent attitude a good aptitude, applying continuous learning techniques, using the Compressed Air Challenge’s excellent training seminars and materials, and seeking out mentorship opportunities have allowed one compressed air auditor to progress from a ”dumb kid” parts clerk to the Vice-President of Business Development for Industrial Air Centers.
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.
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