System Assessments

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.

Responsible companies are looking at ways to not only reduce their energy consumption, but to make their production more efficient. This is a great general business practice, but how can you be sure that what you are doing has positively impacted the bottom line? More specifically, what can you implement that is repeatable as a best practice to save energy, and better yet, what can you implement that can be used to retrofit various machines across your floor? One solution is found in upgrading to modern pneumatic valves capable of saving energy by reducing compressed air consumption

In continuation of our series examining the application of storage in a compressed air system, this article will focus on another type of supply side storage concept: demand (dry) storage. Before discussing the definition, application and use of demand storage, I would like to reiterate that contrary to current thought, consideration should be given to control (wet) and demand (dry) storage being separate storage solutions based on their primary purpose

Compressed air is expensive to produce but when one realizes the actual cost of using compressed air to produce mechanical work it can be mind boggling. Various inefficiencies between the compressor and the ultimate end use can act like a tax, robbing a portion of this valuable energy source before it is used and making the ultimate cost of using compressed air for power far more than you know. Fortunately there are some things that can be done to reduce these costs and improve efficiency.

The subject of compressed air piping has probably had more pages written about it than any other topic, even storage. Like many other topics in “practical” compressed air technology, a significant portion of this is controversial and often directly opposed.

This chemical plant spent an estimated \$3,153,022 annually on energy (steam and electricity) to operate the compressed air system at their facility. The plant staff established their energy costs as 5.3 cents per kWh and \$9.00 /1,000 lbs of steam per hour. The set of projects implemented in this system assessment reduced energy costs by an estimated \$2,794,598 or 88% of current use. In addition, these projects reduce demand on the boiler systems and add reliability and back-up to the compressed air system.

Keeping an open mind is critical in all system assessments. Each client has different priorities and circumstances. In this case, the elimination of the “close-scrapes” with insufficient pressure was the priority. The energy and rental/maintenance savings realized were just an added bonus. In this article, we have focused on the supply-side of the system and how the centrifugal compressors could be made to supply the system reliably – without the need for rental air compressors.

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.

Over the years, analyzing compressed air system operation and efficiency has gone under various names and taken many different shapes and forms. You may know these as; Assessments, Audits, Studies, and Surveys, but in all cases the compressed systems are analyzed using techniques, such as metering and measuring, to assess the system’s performance and identify opportunities for improvement. The problem is that the results of these activities have varied widely; leaving the end-user to try and determine what is usable, credible and implementable. This has led to a lot of “no actions“, resulting in assessments, audits, studies, and surveys being put on the shelf to collect dust.

A couple of key principles must be considered if we want to understand and control the operating costs of your compressed air system. First, compressors pump air, they do not make pressure. The system creates the back pressure which the compressors must pump against. When the compressor delivers more air than the demand requires, the pressure rises and of course, the reverse is also true. Secondly, any component or application which forces the pressure to be higher than necessary creates wasted energy in the system. This waste is not linear to the increase in pressure but can be exponential for many reasons. However, the main contributors are artificial demand and the size of the compressors in the system.