Technology

Compressed Air Best Practices® (CABP) Magazine recently spoke with Rick Stasyshan, Compressed Air and Gas Institute’s (CAGI) Technical Consultant, and Mr. Neil Breedlove of CAGI's Centrifugal Compressor Section and member company, Atlas Copco Compressors, about centrifugal air compressors. Specifically, the discussion outlined how various inlet conditions can impact the performance of centrifugal air compressors.

A common adage that has been quoted many times in this journal is: “If you don’t measure it, you can’t manage it.” This is partly true. It assumes that managers are willing and able to manage the costs and reliability of their compressed air system. Without data, however, they can’t do an effective job. But because managers are at times already overwhelmed with data, more data doesn’t automatically make them a better manager. A better way of saying it is: “Appropriate measurement can make you a better manager.”

“Jurassic Park,” Michael Crichton’s 1990 novel about a theme park full of genetically engineered dinosaurs, circles around one central theme — control. In fact, there are literally nine chapters titled “Control,” and most of those chapters follow the brilliant, chain-smoking systems engineer John Arnold as he ravenously tries to restore the control systems after a catastrophic collapse.

In our discussions with Stephen Titus and James Bowers, National Sales Manager of Titus Air Systems, we talked about several examples of how The Titus Company provided custom-engineered solutions to various customers. The diversity and complexity of these jobs exemplify how The Titus Company has grown from a small distributorship operating out of a townhome to a thriving compressed air and gas solutions provider capable of tackling highly nuanced applications.

In general, this article focuses on the operating principles of centrifugal air compressors, discussing them in simple terms to provide an understanding of application limitations and opportunities. One primary goal is to define often-confusing terminology, such as “rise to surge,” stonewall and surge,” “mass flow,” and “dynamic compression.” This article is not intended to be an engineering discussion of the various types and designs of centrifugal and other air compressors, but rather, a guideline for deciphering operating curves and understanding general performance.

Biogas is an extremely valuable energy source. Originating from biomass, sewage, plants and landfill sites, it is gaining ever-increasing worldwide recognition as a premium source of renewable energy. It is also making a major contribution to the global energy supply mix by replacing existing fossil-fuel sources such as coal, oil and conventional natural gas.

Plug an electrical device into an outlet. Does it work? Great! For some people that’s all that matters. When it comes to compressed air, many manufacturing plants operate the same way. As long as there is enough air, that’s all that matters.

But what if cost control also matters to your company? Smart compressed air users may already know how much air they’re producing, but they also want to know how much air they’re using—and whether they’re using it productively. To find out, they’re taking accurate, real-time measurements using flow meters.

In 1979 I received a call from a business friend that had just purchased his first single-stage base cup blow machine. He was surprised to find out that he actually needed something more than 100 psi of plant air to blow bottles. This was my entry into engineering a polyethylene terephthalate (PET) compressor system. Since then, I have engineered and delivered over 350 systems—from Tobago to Tibet—and many locations in between.

Acrylon Plastics located in Winkler, Manitoba, Canada manufactures an extensive variety of custom plastic parts for a wide range of end use applications. Years ago changes to their production volumes increased the compressed air flows to above what their compressed air system could deliver. As a result the plant pressure would fall to low levels during production peak demands, which negatively affected sensitive compressed air powered machines. In addition to this during light plant loading conditions the air compressors would run inefficiently. Plant personnel tried a variety of strategies to deal with the plant peaks, with the most efficient solution coming as a result of installing VSD style compressors and pressure/flow control.

The beverage industry has been using polyethylene terephthalate (PET) 2-liter plastic bottles primarily for packaging carbonated soft drinks since the 1970s. As that market has grown to encompass bottled drinking water, stretch blow-molding machines continue to produce those plastic bottles. The concept is simple: A pre-form plug is inserted into the blow molding machine heated, and compressed air is injected, “blowing” into the pre-form to create the bottle.