In general, this article focuses on the definitions of terms often used to understand centrifugal air compressor performance. Comments are also made on how to measure power consumption. This article is not intended to be an engineering discussion of the various types and designs of centrifugal and other air compressors.
The 2015 Association of Independent Compressor Distributors (AICD) Membership Conference & Exhibition
The speaker line-up is vendor-neutral and structured to help air compressor sales and service companies improve their businesses. Presentations included an economist updating members on the state of the economy, a utility incentive program update from Clear Result, and a Q&A Session featuring Ron Nordby and Bill Scales.
Centrifugal compressors are dynamic, and each has a characteristic curve of rising pressure as capacity decreases. Without any control system, the compressor would operate along this natural curve. A centrifugal compressor's flow and pressure are typically controlled by a combination of an inlet control device and an unloading valve (UV).
The introduction of rotary screw air compressors controlled by variable speed drives (VSDs) is one of the best energy efficiency innovations introduced to the industry in the past few years. This style of compressor control can significantly reduce the energy wasted by compressors running in the unloaded condition. But the type of VSD control offered by various manufacturers can differ, and some of these differences can affect the efficiency of the system. This article discusses some little known tweaks to VSD compressor control, including some using hidden features that can sometimes be implemented to enhance the savings gained by the installation of this type of compressors.
Compressed Air Best Practices® Magazine recently caught up with Rick Stasyshan, the Compressed Air and Gas Institute’s (CAGI) Technical Consultant, and John Kassin of Cameron to discuss variable inlet guide vanes (IGV). The following interview describes how centrifugal compressor efficiency can be improved thanks to recent developments in IGV technology.
As the 21st century progresses, the environment is becoming very unsettling for distribution in the industrial air compressor industry. The forces of change discussed in Part 1 of this two-part series created a situation very unfamiliar to distribution. The stability experienced by the industry from 1960 to 1990 was displaced by the volatility of the last 25 years. Consolidation of manufacturers and distributors, loss of channel power, evolution of hybrid channels to market, and intense pressure on profitability are just a few of the major forces distribution has had to deal with. Distribution’s tentative reaction to these forces has resulted in both distributors and manufacturers questioning the long-term viability and relevance of distribution in the industrial air compressor industry.
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.
Hannover Messe 2015 attracted 220,000 visitors with 70,000 coming from outside Germany. The show placed a major emphasis on the digitization of manufacturing. Deutsche Messe Board Member Dr. Joachim Kockler said, “Industry 4.0 has arrived. Digital integration is becoming a key aspect of modern manufacturing and this trend is set to continue at a rapid pace.” It is clear our sector is investing in the “Industry 4.0” trend allowing compressed air system key performance indicators to be captured and managed. The goal of this article is to provide readers with a sampling of highlights catching my eye at the show – with apologies to the many companies left out due to editorial space limitations.
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.
There are many distributors in the industrial air compressor industry that are very concerned about the future role of distribution—or, more specifically—if there even is a role for distribution in the new business environment. The industry has changed, and doing business in the current environment is very different from what distribution has become accustomed to. You may describe it as a “changing of the paradigm” or “moving the cheese,” but make no mistake—it has changed drastically. There are examples of progressive distributors that have succeeded in managing change and have adapted their business strategy accordingly.
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.