Industrial Utility Efficiency    

Technology

It is becoming a “best practice” to install a variable frequency drive (VFD) air compressor whenever one is replacing an old air compressor.  As a result, real systems have fixed-speed and VFD air compressors, mixed.  I have observed several VFD compressor sizing methods.  In my last article, I referred to a common method: size one VFD compressor for the whole system.  This can work.  However, if it doesn’t meet a higher peak demand, one or more of the old compressors will be started, and a mixed system results.   Another method is to replace a compressor with the same size, but with a VFD.  If the compressor that was replaced is large, a big VFD is installed.  If small, a small one.

Air Compressors

Knowing when to overhaul a unit is important, and there are certain signs indicating a unit needs attention. Performing routine fluid checks, taking oil samples and routinely checking for bearing vibration can unveil indicators suggesting an upcoming failure. Oil contamination with metal fragments usually indicates parts are wearing. It’s also important to take notice of airend temperature increases. If internal air compressor temperatures go up, it’s a good indicator the cooler may be failing.

Air Treatment

Compressed air is dried to prevent condensation and corrosion which can disrupt manufacturing processes and contaminate products. Water is the primary promotor of chemical reactions and physical erosion in compressed air systems. A myriad of desiccant dryer designs have been devised to provide “commercially dry” air, air having a dew point of -40°F or less, to prevent corrosion.  Desiccant dryers use solid adsorbents in granule form to reduce the moisture content of compressed air.

Blowers

High speed bearing technology is applicable for aeration blowers operating at much higher speeds than the typical 60Hz, 3600RPM for cast multistage units. High Speed Turbo (HST) units are usually single stage (though some utilize multiple cores) and rotate from 15,000 to 50,000RPM. At such high speeds, standard roller bearings cannot offer the industry standard L10 bearing life. Two types of bearing technologies have come to dominate the wastewater treatment market for these types of machines: airfoil and magnetically levitated. Often the two technologies are compared as equals, however, in many significant ways they are not.

Compressor Controls

When a system has the right combination of VFD and base-load air compressors, how do you coordinate their control? What tells the air compressors to run and load, to have just enough (or no) base-load air compressors and a VFD running, all the time air is needed? Appropriate master controls are needed. These controls are often called “sequencers” or “master control systems”.

Instrumentation

Compressed Air Best Practices® Magazine interviewed Mr. Warwick Rampley, the National Sales Manager for Sydney (Australia) based, Basil V.R. Greatrex Pty Ltd. It’s not every day one is asked to deliver a system able to provide both a reliable compressed air dew point of -80°C (-112°F) and high purity nitrogen.  We work with some excellent technology suppliers and have engineered a rather interesting system.  Although our firm was founded in 1919, this application is one of the most demanding we’ve encountered. Basil V.R. Greatrex is a unique company as we focus only on compressed air measurement, compressed air quality and compressed air efficiency.

Pneumatics

The design of wastewater treatment plants is changing, and it has something to do with LEGO® bricks. More specifically, it has to do with how large and complex LEGO structures are built. If you follow the instructions carefully, you build module after module, eventually piecing them together to create a fully functional and cohesive unit.

Vacuum

It’s one thing to move materials during the production process, but when it’s a finished product on the packaging line, choosing the right material handling system is essential. Getting it wrong results in squandered production time when product loss occurs, and wasted raw materials.

Cooling Systems

As a result of compressed air awareness training and a focus on energy management, two facilities in different parts of the world have reduced their compressed air demand substantially by removing vortex style cabinet coolers from some of their electrical panels and reworking the cooling systems.  These facilities were previously unaware of the high cost of compressed air and how much could be saved if other methods of cooling were used. This article describes some of their efforts in demand reduction.
A replacement strategy for air compressors and blowers integrated into a system-level approach towards energy efficiency can deliver significant energy savings and optimize equipment performance. At the Victor Valley Wastewater Reclamation Authority, a blower replacement project yielded annual energy savings of more than 928,000 kWh and $98,000 in energy costs, while improving the reliability of its secondary treatment process. In addition, the agency qualified for important incentives from its electric utility — significantly improving the project economics and resulting in a 2.94-year payback.
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 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.
Many thousands of dollars of annual electrical savings are being achieved worldwide using special purge reduction controls on desiccant air dryers. These controls reduce the expensive purge air that must flow through the dryer to regenerate the desiccant beds. But, unexpected problems with these controls can cause hidden problems that can reduce or eliminate the savings.
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.
“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.
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.”
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.
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.