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

There are many choices of compressor technology and types of controls that can be used for variable demands. Some examples are rotary screw compressors with inlet valve control: variable speed drives: load/unload control; or centrifugal compressors with variable inlet guide vanes. However, in many cases, the efficiency of the overall compression process can be reduced significantly during lower flow demands, leading to more power per unit of air flow being delivered. It is very important to evaluate different available options and see how a plant can run most efficiently.

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

Load-sharing is an important part of a multiple centrifugal-compressor master control system. It minimizes blow-off based on the available turn-down. In addition, remote start-stop saves more energy if load floats between different ranges. Finally, adding a screw compressor and implementing a hybrid control system might save the most energy and provide the best back-up. In any case, a well-instrumented system allows engineers and operators to assess, optimize and tune the system.

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 Canadian chemical plant installed a large heated blower-purge style compressed air dryer, years ago, to condition the instrument air system against freezing temperatures.  The dryer selected was oversized for the connected air compressors and had unused on-board energy savings features.  A compressed air assessment revealed the site air compressors and compressed air dryers were running inefficiently and causing in-plant pressure problems.  Repairs to a compressed air dryer and the replacement of aging air compressors and dryers has reduced compressed air energy costs by 31 percent.
Compressed Air Best Practices® (CABP) Magazine and the Compressed Air and Gas Institute (CAGI) cooperate to provide readers with educational materials, updates on standards and information on other CAGI initiatives. CABP recently caught up with Rick Stasyshan, Technical Director for the Compressed Air and Gas Institute (CAGI) to provide readers with some insights into the benefits of CAGI’s Verified Performance Program for refrigerated compressed air dryers.
Atlas Copco has a long history serving the Houston-based energy and chemical industries with custom-engineered packages. The objective of this article is to show just a few examples of the custom applications typically engineered and manufactured in the Atlas Copco Houston operation. Opened in 2012, Atlas Copco Houston produces standard compressed air dryers as well as completely engineered air dryers for all markets. The air flow capacity of the dryers, produced at this location, vary from 5 to 12,750 scfm. This capacity range covers heatless, heated purge and blower purge air dryers.
In the food and beverage industry, the moment a product leaves the production line, the clock starts ticking down to when that product will no longer be viable for sale or consumption. To combat the clock, modified atmospheric packaging (MAP) techniques are used to help maintain product freshness and increase shelf life. Nitrogen is the most cost effective, efficient and widely used industry solution for a company’s packaging needs—whether it is for manufacturing cheese, coffee, dried snack foods, or fresh and ready-to-eat (RTE) foods. MAP also helps to decrease chances of contamination or spoiling, keeping products on the market for longer and ultimately increasing the reach of distribution.
Plastic injection molding is a common process in manufacturing, and it can be used to produce just about anything. To create a part, molten plastic is injected into a hollow mold, where it is formed and cooled before being ejected from the cavity. Plastic injection molders make a seemingly limitless range of products, from fishing tackle boxes and kayak paddles to tooth brushes and miniscule medical devices.
Sometime in mid-2015, I received a call from a project engineer at a major plastics firm. He had a troubling issue with one of his PET bottle plants. The bottom line was this: They could not run all five high production blow-molding machines at one time—even though they were able to do so 18 months previously.
Any modern food manufacturing facility employs compressed air extensively in the plant. As common as it is, the potential hazards associated with this powerful utility are not obvious and apparent. Food hygiene legislation to protect the consumer places the duty of care on the food manufacturer. For this reason, many companies often devise their own internal air quality standards based upon what they think or have been told are “best practices.” This is no wonder, as the published collections of Good Manufacturing Practices (GMPs) that relate to compressed air are nebulous and difficult to wade through.
Air-operated double diaphragm (AODD) pumps are common to many manufacturing facilities. As estimated by veteran compressed air auditor Hank van Ormer of Air Power USA, approximately 85 to 90 percent of plants in the United States have AODD pumps. They are used for all kinds of liquid transfer applications, like those found in chemical manufacturing, wastewater removal, and pumping viscous food products.
There is always something new to learn about compressed air systems – particularly in regards to compressed air dryer installations. As I discussed in Part 1 of this series, you can make compressed air dryer installations more reliable by understanding the consequences of any modifications you make to the system.  As a continuation of those ideas, Part II explores more ways to make a dryer installation more reliable. Discussions include: the difference between operating a desiccant dryer in a fixed cycle opposed to demand mode, what happens when you operate a heated desiccant dryer with the cooling air turned off, and how to deal with the unintended consequences of dedicating a desiccant dryer to a compressor. 
Compressed Air Best Practices® Magazine and the Compressed Air and Gas Institute have been cooperating on educating readers on the design, features, and benefits of centrifugal compressor systems. As part of this series, Compressed Air Best Practices® (CABP) Magazine recently caught up with Rick Stasyshan, Compressed Air and Gas Institute’s (CAGI) Technical Consultant, and Ian MacLeod of CAGI member company, Ingersoll Rand. During our discussion, we reviewed some of the things readers should consider when installing a centrifugal compressor system.